東北大学研究者紹介

顔写真

シマツ　タケヒト

島津　武仁

Takehito Shimatsu

所属

高等研究機構学際科学フロンティア研究所　先端学際基幹研究部　情報・システム研究領域

職名

教授

学位

博士（工学）（東北大学）

researchmap

https://researchmap.jp/read0168364

J-GLOBAL ID

200901036187762580

学歴 2

東北大学　工学研究科　電子工学

～ 1988年3月31日
東北大学　工学部　電子工学

～ 1986年3月

所属学協会 4

米国電気学会磁性分科(IEEE,Magnetics Society)
日本金属学会
日本磁気学会
エレクトロニクス実装学会

研究キーワード 6

超高真空
磁性薄膜
スパッタリングプロセス
磁気記録媒体
原子拡散接合法
室温接合技術

研究分野 3

ナノテク・材料 / 薄膜、表面界面物性 /
ものづくり技術（機械・電気電子・化学工学） / 電子デバイス、電子機器 /
ものづくり技術（機械・電気電子・化学工学） / 電気電子材料工学 /

受賞 20

244th ECS Meeting Best Student Paper Award

2023年10月　The Electrochemiacl Society　Blade Test in Atmospheric-Pressure Ar Gas to Characterize Bonded Interface Fabricated Using Atomic Diffusion Bonding
244th ECS Meeting Best Paper Award

2023年10月　The Electrochemiacl Society　Preferred Grain Orientation to Enhance Interdiffusion at Room Temperature in Atomic Diffusion Bonding: A Fundamental Study using Ni and Cu Films
第32回マイクロエレクトロニクスシンポジウム(MES2022)ベストペーパー賞

2023年9月　一般社団法人エレクトロニクス実装学会　Cuを微量添加したAg薄膜を用いた大気中の原子拡散接合法における接合性能
Best Presentation Award in 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)

2021年10月　IMSI(電子実装工学研究所)　Atomic Diffusion Bonding using AlN films
Best Presentation Award in 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)

2021年10月　IMSI(電子実装工学研究所)　Surface Contamination Effects on Bonding Performance in Atomic Diffusion Bonding of Wafers using Amorphous Si Thin Films
Best Poster Presentation Award, 2019 6th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)

2019年5月　191st Committee on Innovative Interface Bonding Technology Japan Society for the Promotion of Science (JSPS)　Novel Sputter Film Deposition to Fabricate Thick Films with Extremely Smooth Surface Suitable for Room Temperature Bonding
AiMES 2018 ECS and SMEQ Joint International Meeting Best Paper Award

2018年10月　Electrochemical Society (ECS)　Atomic Diffusion Bonding for Optical Devices with High Optical Density
Magnetics and Optics Research International Symposium(MORIS 2018) Best Poster Award

2018年1月10日　University of New York, Japan Society for thePpromotion of Science　Frequency dependence of microwave-assisted switching in CoCrPt granular perpendicular media
Best Presentation Award Among Invited Papers, 230th Meeting of The Electrochemical Society (ECS), PRiME 2016, Semiconductor Wafer Bonding 14: Science, Technology and Applications

2016年10月3日　Electrochemical Society (ECS)　High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room-Temperature Bonding
第29回エレクトロニクス実装学会春季講演大会優秀賞

2015年7月7日　一般社団法人エレクトロニクス実装学会　Auキャップ付金属薄膜を用いたウエハの大気中室温接合Ⅱ（Cu, Al 薄膜）
エレクトロニクス実装学会 MES2013 秋季大会研究奨励賞

2014年9月4日　一般社団法人エレクトロニクス実装学会
日本磁気学会平成26年度優秀研究賞

2014年9月3日　公益社団法人日本磁気学会
Best Presentation Award, 2014 4th IEEE International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)

2014年7月16日　IEEE CPMT Sociey Japan Chapter　Room Temperature Bonding of Wafers in Air using Au-Ag Alloy Films
マイクロ接合優秀研究賞（ＭＪ賞）

2014年7月4日　一般社団法人溶接学会　原子拡散接合法によるウエハの室温接合技術の現状と課題
田中貴金属工業株式会社「貴金属に関わる研究助成金」MMS賞

2013年3月28日　田中貴金属工業株式会社
SRC情報ストレージ研究推進機構論文賞2011

2012年6月4日　SRC情報ストレージ研究推進機構　Frequency and time dependent microwave assisted switching behaviors of Co/Pt nanodts Appl. Phys. Express, 5（2012）043001(1-3)
Best Presentation Award, 2012 3rd IEEE International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)

2012年5月23日　IEEE CPMT Japan Society　Atomic Diffusion Bonding of Wafers in Air with Thin Au Films and Its Application to Optical Devices Fabrication
SRC情報ストレージ研究推進機構論文賞2010

2011年5月　SRC情報ストレージ研究推進機構　Microwave assisted magnetization switching in Co/Pt multilayer, J. Appl. Phys., Vol.109, 07B748(2011)
石田記念財団平成22年度研究奨励賞

2010年12月　財団法人石田記念財団　高密度ストレージデバイス用の高磁気異方性薄膜材料の開発
田中貴金属工業株式会社第11回「貴金属に関わる研究助成金」プラチナ賞(大賞)

2010年1月19日　田中貴金属工業株式会社　次世代ストレージ・メモリへの応用に向けたL11Co-Pt垂直磁化膜の高性能化

︎全件表示 ︎最初の5件までを表示

論文 314

Ag-3at%Cu 薄膜を用いた大気中の原子拡散接合法における接合性能査読有り

渡部雄貴, 魚本幸, 島津武仁

エレクトロニクス実装学会誌　27　(1)　143-149　2024年1月1日
出版者・発行元：一般社団法人エレクトロニクス実装学会
DOI： 10.5104/jiep.jiep-d-23-00072 　

ISSN：1343-9677

eISSN：1884-121X
Suppression of Surface Roughening of Ag Films by Capping Layer for Ag/Ag Surface Activated Bonding 国際誌査読有り

Yuanhao Cai, Kai Takeuchi, Miyuki Uomoto, Takehito Shimatsu, Eiji Higurashi

2023 IEEE CPMT Symposium Japan (ICSJ)　2023年11月15日
出版者・発行元：IEEE
DOI： 10.1109/icsj59341.2023.10339608 　
Blade Test in Atmospheric-Pressure Ar Gas to Characterize Bonded Interface Fabricated Using Atomic Diffusion Bonding 国際誌査読有り

Hikaru Iemura, Fuki Goto, Miyuki Uomoto, Takehito Shimatsu

ECS Transactions　112　(3)　199-206　2023年9月29日
出版者・発行元：The Electrochemical Society
DOI： 10.1149/11203.0199ecst 　

ISSN：1938-5862

eISSN：1938-6737
Crystal Lattice Rearrangement Occurred at Au/Ag Bonded Interface in Atomic Diffusion Bonding in Vacuum 国際誌査読有り

Fuki Goto, Hikaru Iemura, Miyuki Uomoto, Takehito Shimatsu

ECS Transactions　112　(3)　191-198　2023年9月29日
出版者・発行元：The Electrochemical Society
DOI： 10.1149/11203.0191ecst 　

ISSN：1938-5862

eISSN：1938-6737
Preferred Grain Orientation to Enhance Interdiffusion at Room Temperature in Atomic Diffusion Bonding: A Fundamental Study Using Ni and Cu Films 国際誌査読有り

Miyuki Uomoto, Shun Kikuchi, Fuki Goto, Takehito Shimatsu

ECS Transactions　112　(3)　147-158　2023年9月29日
出版者・発行元：The Electrochemical Society
DOI： 10.1149/11203.0147ecst 　

ISSN：1938-5862

eISSN：1938-6737
Atomic Diffusion Bonding in Air Using Oxide Films 国際誌査読有り

Takehito Shimatsu, Miyuki Uomoto, Hitomi Fukunaga, Hiroyuki Makita, Yudai Suzuki, Yuhei Kozuka, Arina Muraoka, Takayuki Saito

ECS Transactions　112　(3)　173-180　2023年9月29日
出版者・発行元：The Electrochemical Society
DOI： 10.1149/11203.0173ecst 　

ISSN：1938-5862

eISSN：1938-6737
Effect of film thickness on microwave assisted switching behavior 国際誌査読有り

Nobuaki Kikuchi, Katsunari Sato, Masatoshi Hatayama, Takehito Shimatsu, Satoshi Okamoto

2023 IEEE International Magnetic Conference - Short Papers (INTERMAG Short Papers)　2023年5月
出版者・発行元：None
DOI： 10.1109/intermagshortpapers58606.2023.10228446 　
Microwave-assisted switching in granular media with continuous magnetic overlayers for interaction control 査読有り

Nobuaki Kikuchi, Katsunari Sato, Takehito Shimatsu, Satoshi Okamoto

Japanese Journal of Applied Physics　62　(SB)　SB1015-1-SB1015-6　2023年3月1日
出版者・発行元：IOP Publishing
DOI： 10.35848/1347-4065/ac9910 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

Abstract Optimizing switching behavior under a microwave field is a key issue for microwave-assisted magnetic recording. We study the effect of inter-grain exchange coupling induced by a continuous magnetic layer on microwave-assisted switching of CoCrPt-SiO2 granular media. The microwave assistance effect is improved in the low-frequency region by introducing the inter-grain exchange coupling, but the coupling reduces the critical frequency. The maximum assistance effect is almost independent of the film structure since the dual effect cancels each other. Micromagnetic simulations also show similar results on exchange coupling between grains. These results indicate that the inter-grain exchange coupling can be used to optimize the critical frequency of the media in practical applications.
Thermal activation on microwave-assisted magnetization switching in Co/Pt nanodot arrays 国際誌査読有り

Satoshi Mizutani, Nobuaki Kikuchi, Masatoshi Hatayama, Takehito Shimatsu, Satoshi Okamoto

Japanese Journal of Applied Physics　62　(SB)　SB1012-1-SB1012-5　2023年3月1日
出版者・発行元：IOP Publishing
DOI： 10.35848/1347-4065/ac9533 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

Abstract The magnetization switching field is efficiently reduced by exciting precession with a microwave field of GHz frequency. Analytical calculations based on the Landau–Lifshitz–Gilbert equation have revealed that the effect of the thermal activation process plays an important role in magnetization switching behavior under a microwave field. In this study, we experimentally investigated the microwave-assisted magnetization switching (MAS) behavior of Co/Pt nanodot arrays under various microwave field conditions. Experimental results were compared with the calculated effective energy barrier height of MAS. Consequently, all the experimental MAS behaviors can be explained by the effect of thermal activation, but quantitative discussion will require accurate experimental studies.
ATOMIC DIFFUSION BONDING USING ALN FILMS WITH HIGH ELECTRICAL RESISTIVITY 査読有り

A. Muraoka, H. Makita, T. Saitoh, M. Uomoto, T. Shimatsu

Proceedings of WaferBond’22 Conference on Wafer Bonding for Microsystems, 3D- and Wafer Level Integration　23-24　2022年10月
ATOMIC DIFFUSION BONDING OF WAFERS USING VARIOUS OXIDE FILMS 招待有り

T. Shimatsu, M. Uomoto, T. Saito, T. Moriwaki, N. Kato

Proceedings of WaferBond’22 Conference on Wafer Bonding for Microsystems, 3D- and Wafer Level Integration　19-22　2022年10月
Crystal structure deformation and phase transition of AlScN thin films in whole Sc concentration range 国際誌査読有り

Shiro Satoh, Koichi Ohtaka, Takehito Shimatsu, Shuji Tanaka

132　(2)　025103-025103　2022年7月14日
出版者・発行元：None
DOI： 10.1063/5.0087505 　

ISSN：0021-8979

eISSN：1089-7550
Atomic diffusion bonding with oxide underlayers using Al and amorphous Si films for high optical density applications 国際誌査読有り

Gen Yonezawa, Miyuki Uomoto, Takehito Shimatsu

Japanese Journal of Applied Physics　61　(SF)　SF1011-SF1011　2022年6月1日
出版者・発行元：IOP Publishing
DOI： 10.35848/1347-4065/ac5870 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

Abstract Atomic diffusion bonding with oxide underlayers using Al and a-Si films was examined to create a bonded interface with Al2O3 and Si-oxides having large band gaps for high optical density applications. Surface free energy of the bonded interface greater than 2 J m−2 and 100% light transmittance were achieved after annealing at 300 °C in the range of film thicknesses δ on both sides from 0.3 to 0.5 nm using Al films and with δ of around 0.5 nm using a-Si films. Structural analyses revealed that the bonded interface consists of Al2O3 and Si-oxides with oxygen dissociated from oxide underlayers.
Atomic diffusion bonding in air using Ag films 国際誌査読有り

Yuki Watabe, Fuki Goto, Miyuki Uomoto, Takehito Shimatsu

Japanese Journal of Applied Physics　61　(SF)　SF1003-1-SF1003-3　2022年6月1日
出版者・発行元：IOP Publishing
DOI： 10.35848/1347-4065/ac5760 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

Abstract Atomic diffusion bonding (ADB) of wafers at room temperature in air was studied using Ag films. Using an ultra-high vacuum magnetron sputtering system, Ag (20 nm) films with Ti (5 nm) underlayers were deposited. The propagation speed of crystal lattice rearrangement in the bonding process decreased with an increased exposure time of film surfaces to air (texp). Propagation did not occur at texp of 500 s. The cohesion of Ag film surfaces by film surface exposure to air and reduction of the Ag film surface energy by Ag oxide or sulfide formation probably cause ADB performance degradation.
Bonding performance in atomic diffusion bonding of wafers using amorphous Si thin films with smooth surface 国際誌査読有り

T. Amino, M. Uomoto, T. Shimatsu

Japanese Journal of Applied Physics　61　(SF)　SF1002-1-SF1002-3　2022年6月1日
出版者・発行元：IOP Publishing
DOI： 10.35848/1347-4065/ac5871 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

Abstract Amorphous Si films with a low surface roughness of 0.13 nm were used to examine the bonding performance of atomic diffusion bonding of quartz glass wafers at room temperature in vacuum. The high bonding strength was achieved for films with thickness δ of 2–50 nm: the blade could not be inserted between the bonded wafers. Using a vacuum chamber with a base pressure of 1 × 10–6 Pa, the great bonding strength was maintained even with waiting time in vacuum of as long as 3.6 × 103 s from film deposition to bonding. The excellent bonding performance was almost equal to that achieved using Ti films.
Thermal activation in microwave-assisted magnetization switching and its effect on the switching behavior of granular media 国際誌査読有り

Nobuaki Kikuchi, Katsunari Sato, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu, Hirofumi Suto

Physical Review B　105　(5)　054430-1-054430-11　2022年2月25日
出版者・発行元：American Physical Society (APS)
DOI： 10.1103/physrevb.105.054430 　

ISSN：2469-9950

eISSN：2469-9969

詳細を見る詳細を閉じる

Microwave-assisted switching (MAS) has gathered fundamental interest and has been explored for magnetic recording since the switching field can be reduced by exciting magnetization with a microwave field in the GHz range. We theoretically study the effect of thermal activation in MAS and apply the developed analytical method to examine the result of MAS experiments on CoCrPt-SiO2 granular media. The effective energy barrier height for magnetization switching under a microwave field is calculated from the Landau-Lifshitz-Gilbert equation. The calculated energy barrier shows that the thermal activation process plays a crucial role in MAS and modifies the dependences of the switching field on the microwave frequency and amplitude. The switching field decreases with increasing the microwave frequency up to the critical frequency, at which point the switching field abruptly increases. Thermal activation significantly increases the critical frequency and makes the slope of the frequency dependence of the switching field gradual. The maximum assistance effect increases with increasing the microwave field amplitude and is almost independent of the thermal activation. The analytical method quantitatively explains the gradual microwave frequency dependence and high critical frequency observed in MAS experiments on granular media. These results indicate the importance of thermal activation to optimize MAS behavior for practical use.
WBGデバイスを搭載する低熱抵抗、低インダクタンスなパワーモジュール査読有り

平尾章, 堀元人, 池田良成, 島津武仁

Proceedings of the 28th Symposium on Microjoining and Assembly Technology in Electronics　28　149-152　2022年2月
弾性樹脂薄膜を介した半導体チップのダイレクトボンディングに関する研究査読有り

李瑾, 菊地広, 永田憲雅, 島津武仁, 魚本幸

エレクトロニクス実装学会誌　25　(1)　133-140　2022年1月1日
出版者・発行元：一般社団法人エレクトロニクス実装学会
DOI： 10.5104/jiep.jiep-d-21-00070 　

ISSN：1343-9677

eISSN：1884-121X
Atomic Diffusion Bonding of Wafers with Oxide Underlayers using Thin Hf Films for Optical Applications 査読有り

G. Yonezawa, M. Uomoto, T. Shimatsu

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　52-52　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598448 　
Atomic Diffusion Bonding using Y2O3 and ZrO2 films 査読有り

T. Shimatsu, H. Yoshida, M. Uomoto, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, K. Miyamoto

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　51-51　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598449 　
Atomic Diffusion Bonding using AlN films 査読有り

M. Uomoto, H. Yoshida, T. Shimatsu, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, K. Miyamoto

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　45-45　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598193 　
Surface Contamination Effects on Bonding Performance in Atomic Diffusion Bonding of Wafers using Amorphous Si Thin Films 査読有り

T. Amino, M. Uomoto, T. Shimatsu

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　40-40　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598433 　
Preliminary Study of Atomic Diffusion Bonding in Air using Ag films 査読有り

Y. Watabe, F. Goto, M. Uomoto, T. Shimatsu

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　39-39　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598421 　
Sputtering Technique to Fabricate Smooth Surface Oxide Film for Room Temperature Bonding 査読有り

T. Saito, T. Hanasaki, T. Moriwaki, T. Goto, A. Takeda, A. Miura, M. Uomoto, T. Shimatsu

2021 7th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D)　5-5　2021年10月5日
出版者・発行元：IEEE
DOI： 10.1109/ltb-3d53950.2021.9598432 　
Bonding Performance and Interface Contamination in Atomic Diffusion Bonding of Wafers Using Ti Thin Films 査読有り

T. Amino, M. Uomoto, T. Shimatsu

ECS Journal of Solid State Science and Technology　10　(5)　054008-054008　2021年5月25日
出版者・発行元：The Electrochemical Society
DOI： 10.1149/2162-8777/ac0113 　

ISSN：2162-8769

eISSN：2162-8777
First Demonstration of a High‐Speed and High‐Power‐Tolerance InGaAs/Si Photodiode Fabricated by Atomic Diffusion Bonding 査読有り

Yuki Yamada, Masahiro Nada, Miyuki Uomoto, Takehito Shimatsu, Fumito Nakajima, Hideaki Matsuzaki

Physica Status Solidi (A) Applications and Materials Science　218　(3)　2000395-1-2000395-5　2021年2月
出版者・発行元：None
DOI： 10.1002/pssa.202000395 　

ISSN：1862-6300

eISSN：1862-6319
SiC/Ni中間層を用いたGaN基板の常温接合

竹内魁, 須賀唯知, Mu Fengwen, 魚本幸, 島津武仁

エレクトロニクス実装学術講演大会講演論文集　35　17A3-04　2021年
出版者・発行元：一般社団法人エレクトロニクス実装学会
DOI： 10.11486/ejisso.35.0_17a3-04 　
Atomic diffusion bonding of Si wafers using thin Nb films 査読有り

Miyuki Uomoto, Takehito Shimatsu

Japanese Journal of Applied Physicss　59　(SB)　SBBC04-1-SBBC04-3　2020年2月

DOI： 10.7567/1347-4065/ab4b1c 　

詳細を見る詳細を閉じる

published online November 27, 2019
Atomic diffusion bonding using oxide underlayers for optical applications 査読有り

G. Yonezawa, Y. Takahashi, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

Japanese Journal of Applied Physicss　59　(SB)　SBBC03-1-SBBC03-5　2020年2月

DOI： 10.7567/1347-4065/ab4b1e 　

詳細を見る詳細を閉じる

published online November 27, 2019
Sputter film deposition to fabricate thick oxide films with extremely smooth surface suitable for room-temperature bonding 査読有り

T. Saito, H. Makita, T. Moriwaki, Y. Suzuki, N. Kato, S. Wakayanagi, A. Miura, M. Uomoto, T. Shimatsu

Japanese Journal of Applied Physicss　59　(SB)　SBBC02-1-SBBC02-3　2020年2月

DOI： 10.7567/1347-4065/ab4c85 　

詳細を見る詳細を閉じる

published online November 27, 2019
Rearrangement of crystal lattice at a Ag/Ag and Au/Au bonded interface in atomic diffusion bonding 査読有り

Shigenobu Matsuda, Miyuki Uomoto, Ayaka Miura, Takehito Shimatsu

Japanese Journal of Applied Physicss　59　(SB)　SBBC01-1-SBBC01-3　2020年2月

DOI： 10.7567/1347-4065/ab4f27 　

詳細を見る詳細を閉じる

published online November 27, 2019
Minority-electron transport through atomic-diffusion-bonded InGaAs/a-Ge/InGaAs structure studied by photodiode characterization 査読有り

Yuki Yamada, Masahiro Nada, Miyuki Uomoto, Takehito Shimatsu, Fumito Nakajima, Takuya Hoshi, Hideaki Matsuzaki

Japanese Journal of Applied Physicss　59　(1)　016501-1-016501-5　2020年1月

DOI： 10.7567/1347-4065/ab5c65 　
Fabrication of High Power Deep Ultraviolet Light-Emitting Diodes with Glass Lenses Using Atomic Diffusion Bonding 査読有り

M. Ichikawa, T. Kemmochi, T. Mukai, M. Uomoto, T. Shimatsu

ECS Journal of Solid State Science and Technology　9　(1)　015004-1-015004-8　2020年1月

DOI： 10.1149/2.0092001JSS 　
Microwave-assisted switching in CoCrPt granular medium under continuous microwave fields 査読有り

Nobuaki Kikuchi, Katsunari Sato, Shun Kikuchi, Satoshi Okamoto, Takehito Shimatsu, Osamu Kitakami, Hitoshi Osawa, Motohiro Suzuki

Journal of Applied Physics　126　(8)　083908(1-7)　2019年8月
出版者・発行元：None
DOI： 10.1063/1.5111576 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

Published Online: 26 August 2019
Novel Gratings for Astronomical Observations Fabricated by Latest Technologies 査読有り

Noboru Ebizuka, Takayuki Okamoto, Minoru Sasaki, Ichi Tanaka, Miyuki Uomoto, Takehito Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　77　2019年6月

DOI： 10.23919/LTB-3D.2019.8735117 　
Rearrangement of Crystal Lattice Occurred at Ag/Ag Bonded Interface in Atomic Diffusion Bonding 査読有り

S. Matsuda, M. Uomoto, A. Miura, T. Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　67　2019年6月

DOI： 10.23919/LTB-3D.2019.8735204 　
Atomic Diffusion Bonding of Wafers using a-Ge Films with Extremely Low Electrical Conductivity 査読有り

A. Muraoka, M. Uomoto, M. Abe, T. Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　66　2019年6月

DOI： 10.23919/LTB-3D.2019.8735352 　
Atomic Diffusion Bonding of Wafers Using Thin Nb Films 査読有り

M. Uomoto, T. Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　65　2019年6月

DOI： 10.23919/LTB-3D.2019.8735105 　
Novel Sputter Film Deposition to Fabricate Thick Films with Extremely Smooth Surface Suitable for Room Temperature Bonding 査読有り

T. Saito, H. Makita, T. Moriwaki, Y. Suzuki, N. Kato, S. Wakayanagi, A. Miura, M. Uomoto, T. Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　64　2019年6月

DOI： 10.23919/LTB-3D.2019.8735262 　
Oxidation of Bonded Thin Ti Films Using Oxide Underlayers in Atomic Diffusion Bonding Process for Optical Applications 査読有り

G. Yonezawa, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　63　2019年6月

DOI： 10.23919/LTB-3D.2019.8735120 　
Temporary SiC-SiC wafer bonding compatible with high temperature annealing 査読有り

Fengwen Mu, Tadatomo Suga, Miyuki Uomoto, Takehito Shimatsu

Proceedings - Electronic Components and Technology Conference　2019-May　989-994　2019年5月

DOI： 10.1109/ECTC.2019.00155 　

ISSN：0569-5503

詳細を見る詳細を閉じる

© 2019 IEEE. A temporary wafer bonding of SiC-SiC compatible with rapid thermal annealing at ∼1000 °C has been developed. An intermediate Ni nano-layer was employed to realize a strong and seamless bonding of two SiC wafers at room temperature without additional pressure. By the rapid thermal annealing process, the interface strength was remarkably decreased and the de-bonding could be achieved at the annealed interface. Interface analyses were carried out to investigate the mechanisms of both bonding and de-bonding. Further development of this temporary bonding technology is expected to be able to make the fabrication of thin SiC device compatible with the common rapid thermal annealing process.
Temporary SiC-SiC Wafer Bonding Compatible with High Temperature Annealing 査読有り

Fengwen Mu, Tadatomo Suga, Miyuki Uomoto, Takehito Shimatsu

Proceedings of 2019 IEEE 69th Electronic Components and Technology Conference (ECTC)　989-994　2019年5月

DOI： 10.1109/ECTC.2019.00155 　

ISSN：2377-5726
SiC-SiC temporary bonding compatible with rapid thermal annealing at 1000 ℃ 査読有り

Fengwen Mu, Tadatomo Suga, Miyuki Uomoto, Takehito Shimatsu, Kenichi Iguchi, Haruo Nakazawa

Proceedings of 2019 6th International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2019, IEEE　4　2019年5月

DOI： 10.23919/LTB-3D.2019.8735291 　
De-bondable SiC–SiC wafer bonding via an intermediate Ni nano-film 査読有り

Mu, F. Uomoto, M. Shimatsu, T. Wang, Y. Iguchi, K. Nakazawa, H. Takahashi, Y. Higurashi, E. Suga, T

Applied Surface Science　465　591-595　2019年1月28日

DOI： 10.1016/j.apsusc.2018.09.050 　

ISSN：0169-4332
Near-Zero TCF of HAL SAW Resonator with LiTaO3-on-Quartz Structure 査読有り

Michio Kadota, Yoshimi Yunoki, Takehito Shimatsu, Miyuki Uomot, Shuji Tanaka

Proceedings of 2018 IEEE International Frequency Control Symposium (IFCS)　1-4　2019年1月

ISSN：2327-1949
Suprious-Free, Near-Zero-TCF Hetero Acoustic Layer (HAL)SAW Resonators Using LiTaO3Thin Plate on Quartz 査読有り

Michio Kadota, Yoshimi Ishii Yunoki, Takehito Shimatsu, Miyuki Uomoto, Shuji Tanaka

Proceedings of 2018 IEEE International Ultrasonics Symposium (IUS)　1-9　2018年12月

DOI： 10.1109/ULTSYM.2018.8580111 　

ISSN：1948-5727
Atomic Diffusion Bonding for Optical Devices with High Optical Density 査読有り

G. Yonezawa, Y. Takahashi, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

ECS Transactions　86　(5)　233-245　2018年9月

DOI： 10.1149/08605.0233ecst 　
Room Temperature Bonding of Wafers using Si and Ge Films with Extremely Low Electrical Conductivity 査読有り

M. Uomoto, A. Muraoka, T. Shimatsu

ECS Transactions　86　(5)　199-204　2018年9月

DOI： 10.1149/08605.0199ecst 　
Frequency dependence of microwave-assisted switching in CoCrPt granular perpendicular media 査読有り

Nobuaki Kikuchi, Kyohei Shimada, Takehito Shimatsu, Satoshi Okamoto, Osamu Kitakami

Japanese Journal of Applied Physics　57　(9)　09TE02(1-4)　2018年8月
出版者・発行元：None
DOI： 10.7567/JJAP.57.09TE02 　

ISSN：0021-4922

eISSN：1347-4065

詳細を見る詳細を閉じる

published online August 9, 2018
MICROWAVE ASSISTED SWITCHING BEHAVIOR OF COCRPT BASED GRANULAR MEDIA

Nobuaki KIKUCHI, Kyohei SHIMADA, Shun KIKUCHI, Katsunari SATO, Satoshi OKAMOTO, Osamu KITAKAMI, Takehito SHIMATSU

Digest of the 29th Magnetic Recording Conference 2018(TMRC2018)　41-42　2018年8月
Layer-selective microwave-assisted magnetization switching in a dot of double antiferromagnetically coupled (AFC) layers 査読有り

Yuming Lu, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

Applied Physics Letters　112　(16)　162404(1-4)　2018年4月16日
出版者・発行元：American Institute of Physics Inc.
DOI： 10.1063/1.5027127 　

ISSN：0003-6951

詳細を見る詳細を閉じる

Layer-selective magnetization switching is a key technology for three-dimensional magnetic recording. In this study, layer-selective magnetization switching is demonstrated in a dot of double antiferromagnetically coupled (AFC) layers under an assistance of an rf field. Each AFC layer consists of two Co/Pt multilayers with a Ru interlayer. By optimally tuning the rf frequency, the layer-selective switching of each AFC layer is clearly confirmed. However, this layer-selective switching is probabilistic, with a maximum probability of about 65%. The stability of the layer-selective switching is improved if the dipolar field from the first switched AFC layer is suppressed.
CoCrPt-TiO2グラニュラー薄膜におけるマイクロ波アシスト磁化反転挙動

菊池伸明, 島田恭平, 島津武仁, 岡本聡†, 北上修

電子情報通信学会技術研究報告 MR　117　(501)　45-49　2018年3月
Novel torque magnetometry for uniaxial anisotropy constants of thin films and its application to FePt granular thin films 査読有り

Takuya Ono, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

Applied Physics Express　11　(3)　033002(1-3)　2018年3月1日
出版者・発行元：Japan Society of Applied Physics
DOI： 10.7567/APEX.11.033002 　

ISSN：1882-0786 1882-0778

詳細を見る詳細を閉じる

A technique based on torque magnetometry is proposed for precise determination of the uniaxial magnetic anisotropy constant, Ku of perpendicularly magnetized thin films, in particular for Ku larger than 106 J/m3, by electrical detection of the anomalous Hall effect and exact determination of the magnetic field direction. This technique can measure the Ku value of several-nanometer-thick polycrystalline films. Further, the Ku value of FePt-C granular films, which are expected to be useful for high-density magnetic recording media, is evaluated. The intrinsic Ku value of 4-nm-thick FePt-C thin films fabricated at 450 °C is approximately 3 MJ/m3 for carbon contents up to 34 vol % C.
Interface structure of InGaAs wafers bonded using thin amorphous Ge films in vacuum 査読有り

Miyuki Uomoto, Yuki Yamada, Takuya Hoshi, Masahiro Nada, Takehito Shimatsu

Japanese Journal of Applied Physics　57　(2)　02BA03(1-3)　2018年2月1日
出版者・発行元：Japan Society of Applied Physics
DOI： 10.7567/JJAP.57.02BA03 　

ISSN：1347-4065 0021-4922

詳細を見る詳細を閉じる

This study examines room-temperature bonding of InGaAs wafers in vacuum using thin amorphous Ge (a-Ge) films. InGaAs wafers bonded using 0.5-1-nm-thick a-Ge film on respective sides show great bonding strength comparable to the fracture strength of InGaAs after annealing at 340 °C. High-resolution images obtained using transmission electron microscopy show no vacancy at the bonded a-Ge/a-Ge interface and no clear damage of the deposited a-Ge films on the crystal lattices of the InGaAs surfaces. Analysis using electron energy-loss spectroscopy reveals a slight inter-diffusion of Ge and In at the a-Ge/InGaAs interface.
双極子結合した積層磁性ドットによるマイクロ波アシスト実験

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会研究会資料,MAGZ43　43　(234)　21-25　2017年11月
Transmission Gratings and Immersion Gratings for Instruments of Subaru Telescope and TMT 査読有り

N. Ebizuka, T. Okamoto, M. Takeda, T. Hosobata, Y. Yamagata, M. Sasaki, M. Uomoto, T. Shimatsu, S. Sato, N. Hashimoto, I. Tanaka, T. Hattori, S. Ozaki, W. Aoki

Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21　2017年9月
Tuning Magnetic Anisotropy and Curie Temperature of L10-FePt Granular films 招待有り

T. Shimatsu, T. Ono, T. Moriya, H. Nakata, K. Komiyama, S. Uchida, H. Oyama, H. Kikuchi, H. Kataoka, K. Sato, A. Furuta, T. Yoshizawa, M. Hatayama, K. Tsumura, N. Kikuchi, O. Kitakami

Digest of the 28th Magnetic Recording Conference 2017(TMRC2017)　2017年8月

詳細を見る詳細を閉じる

Tsukuba, August(2017) A-1
双極子結合した積層磁性ドットによるマイクロ波アシスト磁化反転

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電子情報通信学会技術研究報告 MR　117　(80)　53-58　2017年6月1日
出版者・発行元：映像情報メディア学会
ISSN：1342-6893

詳細を見る詳細を閉じる

MR2017-8
Influence of intergrain interactions and thermal agitation on microwave-assisted magnetization switching behavior of granular magnetic film 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

APPLIED PHYSICS EXPRESS　10　(2)　023004(1-4)　2017年2月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.7567/APEX.10.023004 　

ISSN：1882-0778

eISSN：1882-0786

詳細を見る詳細を閉じる

Microwave-assisted magnetization switching (MAS) in a granular magnetic film is examined by computer simulation. Contrary to the macrospin calculation and the experiments on single magnetic dots reported so far, in which the switching field linearly decreases with increasing rf frequency and then sharply increases at the critical frequency, the granular film exhibits considerably broad MAS behavior against the rf frequency. This broad MAS behavior is mainly caused by the dispersion of magnetic properties and thermal agitation. On the other hand, intergrain dipolar and exchange interactions enhance the MAS effect in the granular film and suppress the MAS broadening. (C) 2017 The Japan Society of Applied Physics
Diffraction Gratings for the Latest Visible and Infrared Astronomical Observations 査読有り

Noboru EBIZUKA, Takayuki OKAMOTO, Miyuki UOMOTO, Takehito SHIMATSU, Minoru SASAKI, Andrea BIANCO, Chris PACKHAM, Wako AOKI

日本赤外線学会誌　26　(2)　32-39　2017年2月
出版者・発行元：日本赤外線学会
ISSN：0916-7900
Lasing and thermal characteristics of Yb:YAG/YAG composite with atomic diffusion bonding 査読有り

Siva Sankar Nagisetty, Patricie Severova, Taisuke Miura, Martin Smrz, Hitoe Kon, Miyuki Uomoto, Takehito Shimatsu, Masato Kawasaki, Takeshi Higashiguchi, Akira Endo, Tomas Mocek

LASER PHYSICS LETTERS　14　(1)　015001(6pp)　2017年1月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/1612-202X/14/1/015001 　

ISSN：1612-2011

eISSN：1612-202X

詳細を見る詳細を閉じる

We demonstrated the laser performance of an Yb:YAG/YAG composite ceramic laser medium mounted on an aluminium heatsink via atomic diffusion bonding (ADB) technique using nanocrystalline metal films at room temperature in air. The surface temperature rise of the ADB bonded laser medium was linear with 57 degrees C lower than that of the commercially available soldered Yb: YAG thin disk at the pump power of 280 W. Moreover, the ADB disk was pumped 1.5 times higher (7.3 kW cm(-2)) than the typical damage threshold of the soldered disk without any sign of damage. The undoped capping may be effective for the suppression of ASE heating; however, according to the in situ OPD measurement it induces strong thermal lensing. The CW laser output power of 177 W was obtained at the pump power of 450 W with the optical-to-optical efficiency of 40% using V-shape cavity.
Magnetic characteristics and nanostructures of FePt granular films with GeO2 segregant 査読有り

Takuya Ono, Tomohiro Moriya, Masatoshi Hatayama, Kaoru Tsumura, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

APPLIED PHYSICS LETTERS　110　(2)　022402(1-4)　2017年1月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4973473 　

ISSN：0003-6951

eISSN：1077-3118

詳細を見る詳細を閉じる

To realize a granular film composed of L1(0)-FePt grains with high uniaxial magnetic anisotropy energy, K-u, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 degrees C realized uniaxial magnetic anisotropy, K-u(grain), of about 2.5 x 10(7) erg/cm(3), which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the K-u values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high K-u of the FePt-GeO2/FePt-C stacked films. Published by AIP Publishing.
Enhancement of Light Transmittance for Wafers Bonded with Thin Al films using Atomic Diffusion Bonding and Subsequent Laser Irradiation 査読有り

M. Ichikawa, N. Eboshi, T. Kemmochi, M. Sano, T. Mukai, M. Uomoto, T. Shimatsu

2017 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　6-6　2017年
出版者・発行元：IEEE
DOI： 10.23919/LTB-3D.2017.7947402 　

詳細を見る詳細を閉じる

Enhancement of light transmittance was examined for sapphire or synthetic quartz glass wafers bonded with thin Al films using atomic diffusion bonding (ADB). The results indicate that the thin Al film at the bonded interface diffuses into the wafer by subsequent laser irradiation, which enhances the light transmittance through the bonded interface.
Shear Strength of Room-Temperature-Bonded Sapphire and Metal Substrates using Au Films 査読有り

H. Kon, M. Uomoto, N. Nakajima, T. Nakaya, T. Shimatsu

2017 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　48-48　2017年
出版者・発行元：IEEE
DOI： 10.23919/LTB-3D.2017.7947444 　

詳細を見る詳細を閉じる

For sapphire and various metals (Al alloys, Cu alloys, and stainless steel) bonded at room temperature using Au films, shear strength was assessed in this study. Results show extremely high shear strength of all samples: greater than 10 kN (50 MPa).
Demonstration of laser oscillation of an Yb-doped Y2O3 composite disk by use of atomic diffusion bonding in room temperature 査読有り

Takeshi Higashiguchi, Syun Yamauchi, Yusuke Fujii, Natsumi Shinozaki, Takuto Ogura, Miyuki Uomoto, Takehito Shimatsu, Taisuke Miura, Tomas Mocek

2017 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　49-49　2017年
出版者・発行元：IEEE
DOI： 10.23919/LTB-3D.2017.7947445 　

詳細を見る詳細を閉じる

We demonstrate the laser oscillation of an Yb-doped Y2O3 composite disk by use of atomic diffusion bonding (ADB) in room temperature. The continuous wave laser power was observed to be 6 W. We also measured the behavior of the wavefront produced by ADB.
Room Temperature Bonding of InGaAs Wafers using Thin Ge Films 査読有り

M. Uomoto, Y. Yamada, T. Hoshi, M. Nada, T. Shimatsu

2017 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　50-50　2017年
出版者・発行元：IEEE
DOI： 10.23919/LTB-3D.2017.7947446 　

詳細を見る詳細を閉じる

Room temperature bonding of InGaAs wafers using thin Ge films was studied. Wafers were bonded even with 0.5 nm thick Ge film on each side. Bonded wafers showed strong bonding force after annealing at 340 degrees C, with no vacancy at the bonded interface in TEM images.
Novel gratings for next-generation instruments of astronomical observations 査読有り

N. Ebizuka, T. Okamoto, M. Takeda, T. Hosobata, Y. Yamagata, M. Sasaki, M. Uomoto, T. Shimatsu, S. Sato, N. Hashimoto, I. Tanaka, T. Hattori, S. Ozaki, W. Aoki

HOLOGRAPHY: ADVANCES AND MODERN TRENDS V　10233　(10233)　M1-M8　2017年
出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING
DOI： 10.1117/12.2264892 　

ISSN：0277-786X

詳細を見る詳細を閉じる

We will introduce current status of development of a birefringence volume phase holographic (B-VPH) grating, volume binary (VB) grating and reflector facet transmission (RFT) grating developing as the novel dispersive optical element for astronomical instruments for the 8.2m Subaru Telescope, for next generation 30 m class huge ground-based telescopes and for next generation large space-bone telescopes. We will also introduce a hybrid grism developed for MOIRCS (Multi-Object InfraRed Camera and Spectrograph) of the Subaru Telescope and a quasi-Bragg (QB) immersion grating. Test fabrication of B-VPH gratings with a liquid crystal (LC) of UV curable and normal LCs or a resin of visible light curable are performed. We successfully fabricated VB gratings of silicon as a mold with ridges of a high aspect ratio by means of the cycle etching process, oxidation and removal of silicon oxide. The RFT grating which is a surface-relief (SR) transmission grating with sawtooth shaped ridges of an acute vertex angle. The hybrid grism, as a prototype of the RFT grating, combines a high-index prism and SR transmission grating with sawtooth shape ridges of an acute vertex angle. The mold of the SR grating for the hybrid grism on to a work of Ni-P alloy of non-electrolysic plating successfully fabricated by using our ultra-precision machine and a single-crystal diamond bite. The QB immersion grating was fabricated by a combination of an inclined QB grating, Littrow prism and surface reflection mirror.
Addition of Ru to L1(0)-FePt thin film to lower Curie temperature 査読有り

Takuya Ono, Hitoshi Nakata, Tomohiro Moriya, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

APPLIED PHYSICS EXPRESS　9　(12)　1230002(1-3)　2016年12月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.7567/APEX.9.123002 　

ISSN：1882-0778

eISSN：1882-0786

詳細を見る詳細を閉じる

The addition of Ru to L1(0) (fct)-FePt thin films was investigated to lower the Curie temperature (T-c) of the films, which is beneficial for heat-assisted magnetic recording. The FePtRu films exhibited L1(0)-ordering and perpendicular anisotropy for Ru contents up to at least 18 at. %, and T-c was reduced by > 100 degrees C/6 at.% Ru independent of the Fe/Pt ratio between 0.8 and 1.1. The Tc versus uniaxial magnetic anisotropy diagrams exhibited a linear trend similar to that of FePtCu films but with a larger slope. Systematic analysis clarified that the Ru additive caused a slight decrease of the anisotropic field but greatly decreased the saturation magnetization, which was related to the observed reduction in T-c. (C) 2016 The Japan Society of Applied Physics
Radio Frequency Field Dependence of Microwave-Assisted Switching Behaviors of Co/Pt Nanodots 査読有り

Masaki Furuta, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

ELECTRONICS AND COMMUNICATIONS IN JAPAN　99　(8)　79-85　2016年8月
出版者・発行元：WILEY-BLACKWELL
DOI： 10.1002/ecj.11842 　

ISSN：1942-9533

eISSN：1942-9541

詳細を見る詳細を閉じる

Microwave-assisted magnetization switching (MAS) has been expected as one of the prominent future ultra-high-density magnetic recording technologies. In this paper, we have studied the radio frequency (RF) field dependence of the switching behavior of Co/Pt nanodot arrays with various dot diameters. While the critical frequency increases and the minimum switching field decreases with increasing the RF field, MAS behavior critically depends on the dot size. For small dots less than 130nm in diameter, the critical frequency and the minimum switching field exhibit linear variation with the RF field. On the other hand, for the larger dots (dot diameter 230nm), they exhibit not only profound MAS effect but also obvious change in the behavior at a certain RF field. These changes of MAS behaviors are explained as a consequence of the change of magnetization precession mode. On the other hand, the dispersions of MAS effect exhibit no remarkable variation on the RF field. (C) 2016 Wiley Periodicals, Inc.
High-output-power deep ultraviolet light-emitting diode assembly using direct bonding 査読有り

Masatsugu Ichikawa, Akira Fujioka, Takao Kosugi, Shinya Endo, Harunobu Sagawa, Hiroto Tamaki, Takashi Mukai, Miyuki Uomoto, Takehito Shimatsu

APPLIED PHYSICS EXPRESS　9　(7)　072101(1-4)　2016年7月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.7567/APEX.9.072101 　

ISSN：1882-0778

eISSN：1882-0786

詳細を見る詳細を閉じる

We fabricated high-output-power 255 and 280nm light-emitting diodes (LEDs) using direct bonding. The LED chips were bonded to sapphire lenses at room temperature using either atomic diffusion bonding or surface-activated bonding. The LEDs with lenses had a higher light extraction efficiency than conventionally structured LEDs. As a result, at a forward current of 350 mA, the output power of the 255nm LED increased by a factor of 2.8, reaching 73.6 mW, while that of the 280 nm LED increased by a factor of 2.3, reaching 153 mW. (C) 2016 The Japan Society of Applied Physics
Microwave-Assistance Effect on Magnetization Switching in Antiferromagnetically Coupled CoCrPt Granular Media 査読有り

Y. Nakayama, Y. Kusanagi, T. Shimatsu, N. Kikuchi, S. Okamoto, O. Kitakami

IEEE TRANSACTIONS ON MAGNETICS　52　(7)　3201203(1-3)　2016年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2015.2507188 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

We examined microwave-assisted switching properties of an antiferromagnetically coupled (AFC) granular perpendicular medium consisting of CoCrPt-TiO2(5)/Co(0.7)/Ru(0.9)/Co(0.7)/CoCrPt-TiO2(3) (in nanometers). In a saturation remanent state, the magnetization of the lower CoCrPt-TiO2 + Co layer switched its direction to form AFC with that of the upper layer because of a thin-film thickness. We assessed the microwave-assistance effect on magnetization switching from the remanent state to the saturation state of the thick upper layer using an anomalous Hall effect. The reduction of a switching field was most enhanced by the application of microwaves of 10 GHz frequency. The switching field reduction by microwave assistance for the AFC medium, obtained by compensating a thermal agitation effect, was estimated as 26%.
Magnetic Anisotropy and Crystal Domain Variant in L1(0)-FePt Polycrystalline Films 査読有り

A. Hotta, T. Ono, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

IEEE TRANSACTIONS ON MAGNETICS　52　(7)　3200803(1-3)　2016年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2016.2522504 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

We fabricated thin L1(0)-FexPt100-x (x = 46-54 at.%) polycrystalline perpendicular films, and examined the x dependences of the first-and second-order uniaxial magnetic anisotropy, K-u1 and K-u2, in relation to variant formation. The values of K-u1 and K-u2 were estimated from magnetic torque curves at an applied field of 70 kOe obtained using anomalous Hall effect. K-u1 for films with thickness d of 10 nm showed a maximum at x = 50 at.%, which was consistent with the behavior of the order parameter. K-u1 decreased markedly as x increased from 50 at.%, accompanied by an increase of K-u2. In-plane X-ray diffraction analysis revealed that the variant formation increased markedly as x increased, especially beyond x = 50 at.%. Moreover, the relative lattice strain evaluated using a Williamson-Hall plot increased remarkably. The significant reduction of K-u1, accompanied by the enhancement of K-u2, was coincident with variant formation. K-u1 for films with d = 2 nm also showed a maximum at x = 50 at.%. However, the K-u1 similar to x relation showed a good symmetry against Fe content variations from 50 at.%. No increase of K-u2 with increasing x was observed. It is likely that a large tensile stress in the initial film growth, caused by the lattice misfit between FePt and MgO underlayers, suppressed the variant formation in these very thin films.
Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu)-substitution in single-crystalline FePt thin films 査読有り

Takuya Ono, Hitoshi Nakata, Tomohiro Moriya, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

AIP ADVANCES　6　(5)　056011(1-5)　2016年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4943535 　

ISSN：2158-3226

詳細を見る詳細を閉じる

In L1(0) (fct)-FePt thin films, both tuning Fe and Pt concentrations and substitution with third-metal were studied for magnetic characteristic optimization. We investigated single-crystalline FePt-X (X = Mn, Ni, Cu) thin films grown epitaxially on MgO(001) substrates at a substrate temperature of 350 degrees C by changing Fe, Pt, and X contents, and explored the effects of off-stoichiometry and 3d-metal-substitution. The magnetic moment per atom (m) of FePt-X films as a function of the effective number of valence electrons (n(eff)) in 3d metal sites follows the Slater-Pauling-type trend, by which m decreases by the n(eff) deviation from n(eff) = 8, independently of the X metal and the Pt concentration. The magnetic anisotropy (K-u) exhibits n(eff) dependence similar to m. This trend was almost independent of the Pt concentration after compensation using the theoretical prediction on the relation between K-u and Fe/Pt concentrations. Such a trend has been proved for stoichiometric FePt-X films, but it was clarified as robust against off-stoichiometry. The compensated K-u (K-u(comp)) of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the K-u(comp) of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation. (C) 2016 Author(s).
Novel diffraction gratings for next generation Spectrographs with high spectral dispersion 査読有り

N. Ebizuka, T. Okamoto, T. Hosobata, Y. Yamagata, M. Sasaki, M. Uomoto, T. Shimatsu, S. Sato, N. Hashimoto, I. Tanaka, T. Hattori, S. Ozaki, W. Aoki

ADVANCES IN OPTICAL AND MECHANICAL TECHNOLOGIES FOR TELESCOPES AND INSTRUMENTATION II　9912　(9912)　2Z　2016年
出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING
DOI： 10.1117/12.2231949 　

ISSN：0277-786X

eISSN：1996-756X

詳細を見る詳細を閉じる

As a transmission grating, a surface-relief (SR) grating with sawtooth shaped ridges and volume phase holographic (VPH) grating are widely used for instruments of astronomical observations. However the SR grating is difficult to achieve high diffraction efficiency at high angular dispersion, and the VPH grating has low diffraction efficiency in high diffraction orders. We propose novel gratings that solve these problems. We introduce the hybrid grism which combines a high refractive index prism with a replicated transmission grating, which has sawtooth shaped ridges of an acute apex angle. The birefringence VPH (B-VPH) grating which contains an anisotropic medium, such as a liquid crystal, achieves diffraction efficiency up to 100% at the first diffraction order for natural polarization and for circular polarization. The quasi-Bragg (QB) grating which consists of long rectangular mirrors aligned in parallel precisely, like a window blind, achieves diffraction efficiency of 60% or more in higher than the 4th diffraction order. The volume binary (VB) grating with narrow grooves also achieves diffraction efficiency of 60% or more in higher than the 6th diffraction order. The reflector facet transmission (RFT) grating which is a SR grating with sawtooth shaped ridges of an acute apex angle achieves diffraction efficiency up to 80% in higher than the 4th diffraction order.
Invited: High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room-Temperature Bonding 招待有り査読有り

M. Ichikawa, S. Endo, H. Sagawa, A. Fujioka, T. Kosugi, T. Mukai, M. Uomoto, T. Shimatsu

SEMICONDUCTOR WAFER BONDING: SCIENCE, TECHNOLOGY AND APPLICATIONS 14　75　(9)　53-65　2016年
出版者・発行元：ELECTROCHEMICAL SOC INC
DOI： 10.1149/07509.0053ecst 　

ISSN：1938-5862

詳細を見る詳細を閉じる

We reviewed the structural and optical properties of high output power 255 and 280 nm light-emitting diodes (LEDs) bonded with hemispherical lenses made of inorganic materials. The optimal LED structure with a lens to improve the output power for deep ultraviolet LEDs was designed using Monte Carlo simulation. The LED chips were bonded to sapphire lenses at room temperature using either atomic diffusion bonding or surface activated bonding. The bonding of the lenses to the LEDs is experimentally shown to improve the light extraction efficiency, and the light output power of the LEDs with lenses was significantly higher than that of conventional structure LEDs. The output power of a 255 nm LED with a lens was 2.8 times larger than that without a lens, with a maximum external quantum efficiency of 4.56%, and that of the 280 nm LED with a lens was larger by a factor of 2.3.
Necessary Thickness of Au Capping Layers for Room Temperature Bonding of Wafers in Air using Thin Metal Films with Au Capping Layers 査読有り

M. Uomoto, T. Shimatsu

SEMICONDUCTOR WAFER BONDING: SCIENCE, TECHNOLOGY AND APPLICATIONS 14　75　(9)　67-76　2016年
出版者・発行元：ELECTROCHEMICAL SOC INC
DOI： 10.1149/07509.0067ecst 　

ISSN：1938-5862

詳細を見る詳細を閉じる

This study elucidated room temperature bonding of wafers in air using Ag, Al, and Cu films with thin Au capping layers. To avoid oxidation of 20-nm-thick of Ag and Cu films, a 2-nm-thick Au layer was found to be effective. Bonding was achieved in air over the entire area without a loading pressure. However, the necessary thickness of the Au capping layer for 20-nm-thick Al films was 6 nm or more, which is three times thicker than those for Ag and Cu films. The necessary Au layer thickness increased as the thicknesses of Al and Ag layers increased. Moreover, a loading pressure was necessary for bonding using thick films. These results were attributed to increased the surface roughness. However, the necessary Au capping layer thickness for bonding was 1/10 or less of the thickness of Al or Ag layers in the present thickness range of 20-500 nm.
Microwave assisted magnetic recording technologies and related physics 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Masaki Furuta, Osamu Kitakami, Takehito Shimatsu

JOURNAL OF PHYSICS D-APPLIED PHYSICS　48　(35)　353001 (18pp)　2015年9月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/0022-3727/48/35/353001 　

ISSN：0022-3727

eISSN：1361-6463

詳細を見る詳細を閉じる

Microwave assisted magnetic recording (MAMR) has been proposed as one of the prospective recording technologies for forthcoming tera-bit-class magnetic recording. In this paper, the technological and related physical issues of MAMR are reviewed. MAMR is the combined technology of microwave assisted switching (MAS) and spin torque oscillator (STO). MAS is a magnetization switching technology in which magnetization switches through excitation of its precessional motion by a radio frequency (rf) field. The MAS behavior in which nonlinear large angle precession is excited has been a challenging issue from scientific and technological viewpoints. Recently developed theories successfully predict the MAS behavior of a single macrospin in which all spins in a magnet are assumed to behave coherently. For a magnetic element with a size larger than the exchange length, spatially non-uniform magnetization precession modes become dominant instead of the coherent precession mentioned above, resulting in significant enhancement of the MAS effect. This size dependent MAS effect is experimentally very well verified for nanosized dots with perpendicular magnetization. Meanwhile, the STO is used as an rf field generator in MAMR technology. The aforementioned large angle magnetization precession dynamics are also a crucial problem for the stable operation of STO. While various types of STOs have been proposed so far, the optimum structure of STO for MAMR is still under investigation. The combination of the MAS and STO may provide frequency domain recording architecture which enables us to realize a new recording scheme, such as multilevel recording.
Co/Ptナノドットにおけるマイクロ波アシスト磁化反転の交流磁場強度依存性査読有り

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会論文誌A(基礎・材料・共通部門誌)　135　(4)　229-234　2015年4月1日
出版者・発行元：None
DOI： 10.1541/ieejfms.135.229 　

ISSN：1347-5533 0385-4205
Quantized spin waves in single Co/Pt dots detected by anomalous Hall effect based ferromagnetic resonance 査読有り

N. Kikuchi, M. Furuta, S. Okamoto, O. Kitakami, T. Shimatsu

APPLIED PHYSICS LETTERS　105　(24)　242405(1-4)　2014年12月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4904225 　

ISSN：0003-6951

eISSN：1077-3118

詳細を見る詳細を閉じる

Anomalous Hall effect (AHE) based ferromagnetic resonance (FMR) measurements were carried out on perpendicularly magnetized Co/Pt multilayer single dots of 0.4-3 mu m in diameter. The resonance behavior was measured by detecting the decrease of perpendicular magnetization component due to magnetization precession. Resonance behavior was observed as a clear decrease of Hall voltages, and the obtained resonance fields were consistent with the results of vector-network-analyzer FMR. Spin-waves with cylindrical symmetry became significant by decreasing the dot diameter, and quantized multiple resonances were observed in the dot of 0.4 mu m in diameter. The AHE based FMR proposed here is a powerful method to approach magnetization dynamics including spin waves and non-linear behavior excited in a finite nanostructure. (C) 2014 AIP Publishing LLC.
原子拡散接合法による室温接合技術招待有り

島津武仁, 魚本幸, 今一恵

溶接学会第107回マイクロ接合研究委員会資料　41-48　2014年7月4日

詳細を見る詳細を閉じる

MJ-660-2014
Granular nanostructures and magnetic characteristics of FePt-TiO2/FePt-C stacked granular films 査読有り

Takuya Ono, Tomohiro Moriya, Masatoshi Hatayama, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

JOURNAL OF APPLIED PHYSICS　115　(17)　17B709(1-3)　2014年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4861684 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

To realize a granular film composed of L1(0)-FePt grains with high uniaxial magnetic anisotropy energy, K-u, and segregants for heat-assisted magnetic recording, the FePt-TiO2/FePt-C stacked film was investigated. The FePt-TiO2/FePt-C stacked film has well-isolated granular structure with average grain size of 6.7nm because the FePt-TiO2 film follows the FePt-C template film in microstructural growth. However, the K-u value is quite low for total thickness of 9 nm: 5 x 10(6) erg/cm(3). Exploration of the thickness dependence of L1(0)-FePt(001) peaks in XRD spectra and cross-sectional TEM images suggest that degradation of the L1(0) ordering appears near the middle of the FePt-TiO2 layer. The EDX-STEM mapping reveals that Ti atoms exist within the FePt grains in addition to the grain boundary. This indicates the possibility that TiO2 tends to be incorporated into the FePt grains and that it prevents L1(0)-ordering of the FePt grains along the normal-to-plane direction. (C) 2014 AIP Publishing LLC.
Magnetic anisotropy and order structure of L1(0)-FePt(001) single-crystal films grown epitaxially on (001) planes of MgO, SrTiO3, and MgAl2O4 substrates 査読有り

A. Hotta, T. Ono, M. Hatayama, K. Tsumura, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

JOURNAL OF APPLIED PHYSICS　115　(17)　17B712 (1-3)　2014年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4862840 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

L1(0)-FePt(001) single-crystal films were grown epitaxially on SrTiO3(001), MgAl2O4(001), and MgO(001) substrates. Their uniaxial magnetic anisotropy K-u and the order structure were examined for the film thickness t range of 2-14 nm. All series of films show large K-u of 4 x 10(7) erg/cm(3) in the thickness range higher than 10 nm, with order parameter S of 0.8 and saturation magnetization M-s of 1120 emu/cm(3). K-u decreased gradually as t decreased. The K-u reduction was considerable when t decreased from 4 nm to 2 nm. No marked difference in the thickness dependence of K-u was found in any series of films, although the lattice mismatch between FePt and the substrates was markedly different. K-u reduction showed good agreement with the reduction of S for the films on MgAl2O4 and MgO. The K-u similar to S-2 plot showed an almost linear relation, which is in good agreement with theoretical predictions. Transmission electron microscopy images for a FePt film on MgO substrate revealed that the lattice mismatch between FePt(001) and MgO(001) was relaxed in the initial 1 or 2 layers of FePt(001) lattices, which is likely to be true also for two other series of films. (C) 2014 AIP Publishing LLC.
Size dependence of magnetization switching and its dispersion of Co/Pt nanodots under the assistance of radio frequency fields 査読有り

Masaki Furuta, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

JOURNAL OF APPLIED PHYSICS　115　(13)　133914(1-8)　2014年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4870451 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

We have studied the dot size dependence of microwave assisted magnetization switching (MAS) on perpendicular magnetic Co/Pt multilayer dot array. The significant microwave assistance effect has been observed over the entire dot size D ranging from 50 nm to 330 nm examined in the present study. The MAS behavior, however, critically depends on D. The excitation frequency dependence of the switching field is well consistent with the spin wave theory, indicating that the magnetization precession in MAS is in accordance with the well defined eigenmodes depending on the dot diameter. The lowest order spin wave is only excited for D <= 100 nm, and then the MAS effect is well consistent with that of the single macrospin prediction. On the other hand, higher order spin waves are excited for D > 100 nm, giving rise to the significant enhancement of the MAS effect. The dispersion of MAS effect also depends on D and is significantly reduced for the region of D > 100 nm. This significant reduction of the dispersion is attributed to the essential feature of the MAS effect which is insensitive to the local fluctuation of anisotropy field, such as defect, damaged layer, and so on. (C) 2014 AIP Publishing LLC.
Theory and Experiment of Microwave-Assisted Magnetization Switching in Perpendicular Magnetic Nanodots 招待有り査読有り

Satoshi Okamoto, Masaki Furuta, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

IEEE TRANSACTIONS ON MAGNETICS　50　(3)　3200906(1-6)　2014年3月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2013.2281400 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

In this paper, we review the theory and experiment on microwave-assisted magnetization switching in perpendicular magnetic nanodots. Within the framework of the single-macrospin model, the switching condition under radio frequency fields can be analytically derived from the steady-state solutions of the Landau-Lifshitz-Gilbert equation. When the Gilbert damping is not so large, this analysis perfectly coincides with the Stoner-Wohlfarth model under the rotating frame. This calculation also predicts the critical frequency above which no microwave assistance effect is operative. While the above analysis almost explains the experimental results on nanodots of a Co/Pt multilayer, the nanodots exhibits unusual size-dependent switching behaviors. For the dot as small as 50 nm, the switching behaviors agree with the analytical calculations based on the single-macrospin model. In contrast, for the dot diameter >100 nm, the significantly enhanced assistance effect is observed. This enhancement for larger dot can be explained by excitation of spatially nonuniform precessional motion in the dots.
Quasi-ballistic magnetization switching in Co/Pt dots with perpendicular magnetization 査読有り

N. Kikuchi, Y. Suyama, S. Okamoto, O. Kitakami, T. Shimatsu

APPLIED PHYSICS LETTERS　104　(11)　112409(1-4)　2014年3月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4869150 　

ISSN：0003-6951

eISSN：1077-3118

詳細を見る詳細を閉じる

A transverse pulse magnetic field with fast rise time generates precessional motion of magnetization due to finite torque. If the torque is sufficiently large enough magnetization may switch irreversibly via a ballistic trajectory even when energy barrier exists between two energetically stable states. We demonstrate magnetization switching in Co/Pt multilayer nanostructured dots via quasi-ballistic magnetization motion excited by a pulse field with subnanoseconds rise time. The quasi-ballistic switching has been found when the rise time of a pulse field is comparable to the half of magnetization precession period, beating the Stoner-Wohlfarth switching limit. (C) 2014 AIP Publishing LLC.
Room Temperature Bonding of Sapphire with Sapphire or Metal Substrates in Air using Au Films 査読有り

M. Ishii, H. Kon, M. Uomoto, T. Nakaya, T. Shimatsu

2014 4TH IEEE INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　27-27　2014年
出版者・発行元：IEEE
DOI： 10.1109/LTB-3D.2014.6886166 　

詳細を見る詳細を閉じる

Room temperature bonding of sapphire-sapphire and sapphire-metal substrates was achieved in Air using Au films. This bonding technique can support expansion of the potential applications of sapphire in diverse industries.
Room Temperature Bonding of Wafers in Air using Au-Ag Alloy Films 査読有り

H. Kon, M. Uomoto, T. Shimatsu

2014 4TH IEEE INTERNATIONAL WORKSHOP ON LOW TEMPERATURE BONDING FOR 3D INTEGRATION (LTB-3D)　28-28　2014年
出版者・発行元：IEEE
DOI： 10.1109/LTB-3D.2014.6886167 　

詳細を見る詳細を閉じる

Room temperature bonding of wafers in air using Au-Ag alloy films was studied. Experimental results show that the bonding using Au-Ag alloy films containing Ag content up to 70-80 at% shows almost equal bonding performance in air to that obtained using Au films.
Au薄膜を用いた大気中のウエハ室温接合における大気暴露時間と接合性能査読有り

今一恵, 魚本幸, 島津武仁

エレクトロニクス実装学会誌　17　(5)　431-435　2014年
出版者・発行元：None
DOI： 10.5104/jiep.17.431 　

ISSN：1884-121X 1343-9677

詳細を見る詳細を閉じる

http://www.e-jisso.jp/publish/journal/pdf/175/A_jiep17050431.pdf
Invited: Room Temperature Bonding Using Thin Metal Films (Bonding Energy and Technical Potential) 招待有り査読有り

T. Shimatsu, M. Uomoto, H. Kon

SEMICONDUCTOR WAFER BONDING 13: SCIENCE, TECHNOLOGY, AND APPLICATIONS　64　(5)　317-328　2014年
出版者・発行元：ELECTROCHEMICAL SOC INC
DOI： 10.1149/06405.0317ecst 　

ISSN：1938-5862

詳細を見る詳細を閉じる

Room temperature bonding using thin metal films uses two flat wafer surfaces with sputter deposition. Then two films on wafers are bonded in vacuum or in air. Bonding in vacuum can be accomplished using almost any metal film, even with film thickness of a few angstroms on each side. The bonding energy is greater than the surface energy of metal films at thicknesses greater than the critical film thickness, which is related to the formation of thin reactive layers between metal films and wafers. Bonding in air using Au films also shows a bonding energy greater than the surface energy of Au films, even with an exposure time of Au films to air of 168 h (1 week). Bonding of wafers and mirror-polished metals was also achieved, which is effective for enhancing the heat dissipation efficiency.
Co/Ptナノドットにおけるマイクロ波アシスト効果のサイズ依存性

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会マグネティックス研究会資料　MAG-13-132　2013年12月
Microwave assistance effect on magnetization switching in Co-Cr-Pt granular film 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Akira Hotta, Masaki Furuta, Osamu Kitakami, Takehito Shimatsu

APPLIED PHYSICS LETTERS　103　(20)　202405(1-4)　2013年11月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.4830364 　

ISSN：0003-6951

eISSN：1077-3118

詳細を見る詳細を閉じる

Experimental verification of microwave assistance effect on a perpendicular magnetic CoCrPt based granular film is demonstrated. Significant reduction of coercivity under the assistance of a radio frequency (rf) field is clearly observed. But the coercivity strongly depends on the duration of rf field, indicating that the magnetic moments of constituent grains are severely perturbed by thermal agitation. Analysis based on the Neel-Arrhenius law has revealed that the dynamic coercivity in nanosecond region can be reduced by 50% only by applying a small rf field with the amplitude less than 2% of the anisotropy field. (C) 2013 AIP Publishing LLC.
Co/Ptナノドットアレイを用いたマイクロ波アシスト磁化反転実験とその反転挙動解析

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会マグネティックス研究会資料　MAG-13-071　2013年8月
Co/Ptナノドットアレイを用いたマイクロ波アシスト磁化反転とその反転挙動

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電子情報通信学会技術研究報告 MR　113　(102)　7-11　2013年6月21日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2013-2
マイクロ波アシスト磁化反転における解析的考察と実験検証

岡本聡, 古田正樹, 菊池伸明, 北上修, 島津武仁

電子情報通信学会技術研究報告 MR　113　(102)　33-38　2013年6月21日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2013-5
原子拡散接合法によるウエハの室温接合技術の現状と課題招待有り

島津武仁, 魚本幸, 今一恵

溶接学会第103回マイクロ接合研究委員会資料　11-18　2013年5月24日
Stoner–Wohlfarth Like Magnetization Switching in Very Small Co/Pt Nanodots under the Assistance of Radio Frequency Magnetic Field 査読有り

Masaki Furuta, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

Applied Physics Express　6　(5)　053006(1-4)　2013年5月
出版者・発行元：None
DOI： 10.7567/APEX.6.053006 　

ISSN：1882-0778

eISSN：1882-0786

詳細を見る詳細を閉じる

published online May 13, 2013
Switching Behaviors and its Dynamics of a Co/Pt Nanodot Under the Assistance of rf Fields 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Masaki Furuta, Osamu Kitakami, Takehito Shimatsu

PHYSICAL REVIEW LETTERS　109　(23)　237209(1-4)　2012年12月
出版者・発行元：AMER PHYSICAL SOC
DOI： 10.1103/PhysRevLett.109.237209 　

ISSN：0031-9007

詳細を見る詳細を閉じる

We have studied the switching behavior of a single Co/Pt multilayer dot under the assistance of rf fields. The switching field monotonically decreases with increasing rf frequency up to a critical frequency. It is found that the reduction of the switching field is more significant than the theoretical prediction based on the single macrospin model. In addition, switching field distribution due to thermal fluctuation is also considerably suppressed. The simulation has revealed that these drastic changes are caused by excitation of large amplitude spin waves in the dot. DOI: 10.1103/PhysRevLett.109.237209
マイクロ波アシストにおけるCo/Pt ナノドットの磁化反転挙動

岡本聡, 菊池伸明, 古田正樹, 北上修, 島津武仁

日本磁気学会第186回研究会資料　186　5-10　2012年11月2日
出版者・発行元：日本磁気学会
ISSN：1882-2940

詳細を見る詳細を閉じる

186-2
Write Margin Measurement of Bit Patterned Media With 20 nm Dots 査読有り

Hideki Saga, Kazuki Shirahata, Ryo Terashima, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka

IEEE TRANSACTIONS ON MAGNETICS　48　(11)　3723-3726　2012年11月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2012.2198796 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Bit-patterned media (BPM) with 20 nm diameter dots and a 72 nm dot period were fabricated from hard/soft-stacked base media with a [Co/Pt]-super-lattice hard layer and a Co soft layer. The write margin of synchronous recording was evaluated using a static tester. All recorded dots were in single domain state, as expected from previous experiments. The write margin was about 50 nm, and there was a total margin loss almost corresponding to the dot diameter. According to an analysis of margin loss factors based on the slope recording model, the margin loss factors for compensating effect of multidomain dots decreased drastically. Therefore it was confirmed that the slope recording model well illustrated the recording process of small dots in single-domain states. The margin loss factor due to the dot position jitter was 17.7 nm(p-p) and became the dominant loss factor. The loss factor attributable to the switching field distribution also increased rapidly to 11.3 nm(p-p) and was the second largest loss factor. To secure a sufficient write margin for a robust recording system, suppression of these degradation factors in the BPM fabrication process is required.
Significant Reduction of Switching Field and its Distribution in Co/Pt Nanodots with Assistance of Radio Frequency Field 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Masaki Furuta, Osamu Kitakami, Takehito Shimatsu

APPLIED PHYSICS EXPRESS　5　(9)　093005(1-3)　2012年9月
出版者・発行元：JAPAN SOC APPLIED PHYSICS
DOI： 10.1143/APEX.5.093005 　

ISSN：1882-0778

詳細を見る詳細を閉じる

Microwave assisted magnetization switching (MAS) is a key technology for future ultra high-density magnetic recording. To explore the feasibility of MAS, we have studied how the magnetization switching behavior of individual Co/Pt multilayer nanodots with perpendicular magnetic anisotropy is modified by the application of rf fields. It is found that the behavior depends on the rf field amplitude. For a large rf field but much smaller than the effective perpendicular anisotropy field, the switching field can be reduced remarkably. Moreover, the broad dispersion of the switching field in the absence the of rf field also becomes quite narrow. (C) 2012 The Japan Society of Applied Physics
垂直磁気異方性を有するナノ磁性ドットを用いたマイクロ波アシスト磁化反転

岡本聡, 菊池伸明, 古田正樹, 北上修, 島津武仁

マグネティクス研究会資料　2012年8月
Co/Ptナノドットを用いたマイクロ波アシスト磁化反転

岡本聡, 菊池伸明, 古田正樹, 北上修, 島津武仁, 青井基

電子情報通信学会技術研究報告 MR　112　(80)　21-24　2012年6月14日

詳細を見る詳細を閉じる

MR2012-4
Dry-etching damage to magnetic anisotropy of Co-Pt dot arrays characterized using anomalous Hall effect 査読有り

T. Shimatsu, H. Kataoka, K. Mitsuzuka, H. Aoi, N. Kikuchi, O. Kitakami

JOURNAL OF APPLIED PHYSICS　111　(7)　07B908(1-3)　2012年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3676061 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

Using high-resolution e-beam lithography and ion beam etching, dot arrays were formed from Co-Pt alloy films with perpendicular magnetization. Dry-etching damage to uniaxial magnetic anisotropy K-u of the fabricated dot arrays was examined. Hcp-Co75Pt25 films and L1(1)-type Co50Pt50-ordered alloy films with film thickness delta of 3, 5, and 10 nm were used for this study. Dot diameter D was varied from 10 nm to 400 nm. The effective magnetic anisotropy of the dots, K-u(eff), was measured using the generalized Sucksmith-Thompson method with anomalous Hall effect (AHE) and an averaged AHE signal over 100-71,000 dots. By compensating the dot shape anisotropy, K-u was calculated from K-u(eff). The K-u for a dot array of D = 400 nm was almost equal to that for an original continuous film, but Ku decreased gradually for D < 30 nm. The circumferential area (periphery) of dots with width W-D was assumed to be damaged by etching. The damaged area was inferred as K-u = 0 with original saturation magnetization M-s. The W-D values, as estimated using experimental data, were 1.6-1.8 nm for hcp-Co75Pt25 dot arrays independent of delta (delta = 3-10 nm) and 1.8-1.9 nm for L1(1)-Co50Pt50 dot arrays (delta = 3-5 nm). For all dot arrays, K-u at D = 10 nm were nearly half those for the original continuous films, suggesting that films having K-u of twice that for original films were necessary to overcome K-u reduction by etching damage. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676061]
Frequency and Time Dependent Microwave Assisted Switching Behaviors of Co/Pt Nanodots 査読有り

Satoshi Okamoto, Nobuaki Kikuchi, Jin Li, Osamu Kitakami, Takehito Shimatsu, Hajime Aoi

APPLIED PHYSICS EXPRESS　5　(4)　043001(1-3)　2012年4月
出版者・発行元：JAPAN SOC APPLIED PHYSICS
DOI： 10.1143/APEX.5.043001 　

ISSN：1882-0778

詳細を見る詳細を閉じる

Microwave assisted magnetization switching is implemented for Co/Pt multilayer nanodots. Application of rf fields significantly reduces the switching field of Co/Pt nanodots, and the reduction behavior is similar to that predicted by macrospin simulation. However, some dots are inert to rf fields. These very different switching behaviors may be attributable to a slight difference in the nucleation process of a reversed domain. It is also found that the switching field reduction remains almost constant regardless of the pulse width and interval of rf fields, indicating that the switching event is sufficiently fast and reliable in the ns regime. (C) 2012 The Japan Society of Applied Physics
Atomic diffusion bonding of wafers in air with thin Au films and its application to optical devices fabrication 査読有り

T. Shimatsu, M. Uomoto, K. Oba, Y. Furukata

Proceedings of 2012 3rd IEEE International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2012　103　2012年

DOI： 10.1109/LTB-3D.2012.6238063 　

詳細を見る詳細を閉じる

Atomic diffusion bonding (ADB) of two flat wafers in air with Au films was studied. Experimental results indicate that wafers can be bonded in air with bonding strength of greater than 25 MPa using only 1 nm total thickness of Au and Cr underlayer on each side. © 2012 IEEE.
Atomic diffusion bonding with thin nanocrystalline metal films in vacuum and in an inert gas 査読有り

T. Shimatsu, M. Uomoto

Proceedings of 2012 3rd IEEE International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2012　155　2012年

DOI： 10.1109/LTB-3D.2012.6238077 　

詳細を見る詳細を閉じる

Atomic diffusion bonding (ADB) of two flat wafers in an inert gas with thin metal films was studied. Its performance was compared to that of ADB "in vacuum." Results suggest that ADB can be conducted in Ar gas using almost any metal film, as is true also for bonding in vacuum. © 2012 IEEE.
Impact of Multidomain Dots on Write Margin in Bit Patterned Media Recording 査読有り

Hideki Saga, Kazuki Shirahata, Kaname Mitsuzuka, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka

IEEE TRANSACTIONS ON MAGNETICS　47　(10)　2528-2531　2011年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2011.2157478 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Bit-patterned media (BPM) samples were fabricated from hard/soft-stacked [exchange-coupled composite (ECC)] base media with a [Co/Pt]-super-lattice hard layer and a Co soft layer. The write margin of synchronous recording was evaluated using a static tester. The write margin of 50 nm dots with a 120 nm period was confirmed to be 65 nm and a large margin loss almost corresponding to the dot diameter was due to the occurrence of multidomain (MD) dots. Behavior analysis of the average MD dot formation rates within the transition regions beside the write window revealed that recording dots with diameters 30 nm, or smaller, are required to eliminate MD dots. A close association between the MD dot formation rate and the write error rate was confirmed. Therefore, a reduction of the large margin loss arising from the MD dots and a resultant improvement in the write error rate is expected when the recording dots become smaller than 30 nm.
Magnetic anisotropy and order parameter for L10 type FePt polycrystalline films with (001) preferred grain orientation 査読有り

D. Inoue, T. Shimatsu, Y. Inaba, H. Aoi, S. Okamoto, O. Kitakami

Journal of Applied Physics　in press　2011年9月

詳細を見る詳細を閉じる

6722
Temperature dependence of the magnetic properties of L11-type Co–Ni–Pt ordered alloy films for thermally assisted recording media 査読有り

Junichi Sayama, Takehito Shimatsu, Hiroaki Nemoto, Satoshi Okamoto, Osamu Kitakami, Hajime Aoi

Journal of Applied Physics　110　(1)　013918(1-5)　2011年7月
出版者・発行元：None
DOI： 10.1063/1.3608123 　

ISSN：0021-8979
スタティックテスタによるパターン媒体の記録マージンの測定査読有り

白幡一樹, 嵯峨秀樹, 三浦健司, 島津武仁, 青井基, 村岡裕明

Journal of the Magnetics Society of Japan　35　(3)　171-174　2011年5月1日
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/msjmag.1104R002 　

ISSN：1882-2924

詳細を見る詳細を閉じる

Bit patterned media (BPM) recording has been studied as one of the possible candidates for future perpendicular magnetic recording. For the basic R/W evaluating of BPM system, small areas of media samples are suitable in most cases. A static tester is useful to measure such small areas of BPM to evaluate their read-write characteristics. We have prepared a tester, and found that measurement with write synchronization was possible. We report here the experimental results obtained from investigations into the write-margin measurements of the BPM. A position margin of 50∼71 % of the dot period was confirmed, and we found the margin loss was related to the formation of multi-domain dots.
Experimental write margin analysis of bit patterned media 査読有り

Hideki Saga, Kazuki Shirahata, Kaname Mitsuzuka, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka

JOURNAL OF APPLIED PHYSICS　109　(7)　07B721(1-3)　2011年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3554201 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Write margin analysis of the bit patterned media (BPM) was experimentally carried out using a static tester. Sample BPM were fabricated from hard/soft-stacked (exchange-coupled composite; ECC) base media with a Pt/Co multilayer hard layer and a Co soft layer. Write margins of 60-nm-dot (140 nm period) and 40-nm-dot (100 nm period) media were confirmed to be 80 nm and 50 nm, respectively. An analysis of the margin loss factor found a large residual margin loss. The loss factors of 60-nm-dot and 40-nm-dot media were 57 nm and 44 nm, respectively, and these values almost correspond to the dot diameter. The residual margin loss was identified as due to the formation of a multi-domain structure within some dots under certain recording conditions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554201]
Dot arrays of L1(0)-type FePt ordered alloy perpendicular films fabricated using low-temperature sputter film deposition 査読有り

T. Shimatsu, Y. Inaba, H. Kataoka, J. Sayama, H. Aoi, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　109　(7)　07B726(1-3)　2011年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3556697 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Using ultrahigh vacuum sputter film deposition, we fabricated L1(0)-type Fe50Pt50 ordered alloy perpendicular films on MgO(001) single-crystal substrates and 2.5 in. glass disks at low substrate temperatures of 200-350 degrees C. Then we examined the magnetic properties of the dot arrays made from these films. The uniaxial magnetic anisotropy K-u for L1(0)-type FePt films (10 nm in thickness) deposited with a Pd underlayer on MgO(001) substrates reached about 2 x 10(7) erg/cm(3) at the substrate temperature T-s of 200 degrees C, and 3 x 10(7) erg/cm(3) at T-s = 250 degrees C. The order parameter S was about 0.46 at T-s = 300 degrees C. Moreover, K-u for L1(0)-FePt films fabricated on glass disks using MgO/Cr underlayers shows 3.4 x 10(7) erg/cm(3) at T-s = 300 degrees C, which was almost equal to that for FePt single-crystal films deposited on Pd/MgO(001). The switching field distribution sigma/H-c for dot arrays made from L1(0)-FePt film [5 nm in thickness, on Pd/ MgO(001) at T-s = 250 degrees C] was small; sigma/H-c = 0.11 for a dot diameter of 15 nm. This value was smaller than that of hcp-Co75Pt25 dot arrays (sigma/H-c = 0.18). The difference was mainly attributable to the degree of the easy axis distribution. This result demonstrates the homogeneous formation of a L10-type ordered structure in the FePt layers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556697]
Characterization of coercivity at a recording speed of granular media for thermally assisted recording 査読有り

D. Inoue, Y. Inaba, K. Komiyama, T. Shimatsu

JOURNAL OF APPLIED PHYSICS　109　(7)　07B727(1-3)　2011年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3556698 　

ISSN：0021-8979

詳細を見る詳細を閉じる

As a fundamental study of thermally assisted recording, remanence coercivity at recording speed and the energy barrier for magnetization switching for granular media were evaluated as a function of temperature T. We characterized those for CoPtCr-oxide granular media as a trial examination. Remanence coercivity was measured at measurement time t' of 1 s (using an electromagnet) and 10(-5) s (pulse field); they were defined, respectively, as H(r) and H(r)(P) for T of 300-473 K. Assuming that the value of t' at a recording speed is 1 ns and the value of remanence coercivity at the recording speed, H(r)(1 ns), was evaluated by fitting H(r) and H(r)(P) to Sharrock's equation. Moreover, the values of the energy barrier for magnetization switching, Delta E, were estimated. The value of H(r)(1 ns) at T = 573 K, which is a typical temperature for thermally assisted recording, as estimated by extrapolation was about 6.2 kOe for the single medium and 5.5 kOe for the stacked medium. These values were about 1 order of magnitude larger than those of H(r) at T = 573 K. Moreover, the reduction ratio of Delta E on increasing T showed good agreement with that of perpendicular uniaxial magnetic anisotropy, K(u). These results indicate that a large K(u) reduction on increasing T was necessary to enhance the reduction of recording coercivity at elevated recording temperatures. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556698]
Microwave assisted magnetization switching in Co/Pt multilayer 査読有り

S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu, H. Aoi

JOURNAL OF APPLIED PHYSICS　109　(7)　07B748(1-3)　2011年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3561780 　

ISSN：0021-8979

詳細を見る詳細を閉じる

In this study, we have experimentally investigated the microwave assisted magnetization by switching (MAS) on the microstructured Co/Pt multilayer. The sample exhibits the typical magnetization curve peculiar to perpendicular anisotropy films, that is, a steep reversal initiated by nucleation of a reversed domain followed by its subsequent gradual expansion by the domain wall displacement. By applying microwaves with the frequency of GHz order, the nucleation field H-n is significantly reduced at three frequencies. Taking into account the effective anisotropy field of our sample, the first dip of H-n at the lowest frequency probably corresponds to the Kittel mode excitation, and the other two dips at higher frequencies correspond to unidentified excitation modes other than the Kittel mode. Among them, the last dip of H-n at the highest frequency reaches about 1/3 of that without microwave application. These results suggest the existence of more effective excitation modes for MAS than the Kittel mode. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3561780]
スタティックテスタによるBPMの記録マージンの検討

白幡一樹, 嵯峨秀樹, 三浦健司, 島津武仁, 青井基, 村岡裕明

電子情報通信学会技術研究報告 MR　110　(329)　39-43　2010年12月2日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2010-47
Atomic diffusion bonding of wafers with thin nanocrystalline metal films 査読有り

T. Shimatsu, M. Uomoto

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B　28　(4)　706-714　2010年7月
出版者・発行元：A V S AMER INST PHYSICS
DOI： 10.1116/1.3437515 　

ISSN：1071-1023

詳細を見る詳細を閉じる

Bonding between two flat wafers with thin metal films was studied for 14 thin metal films with various crystal structures and self-diffusion coefficients. Thin nanocrystalline metal films were fabricated on two flat wafers' surfaces using sputter deposition. Bonding of the two metal films on the wafers was accomplished immediately after film deposition in vacuum. For the films, Al, Au, Ag, Cu, Si, Co, Ni, Pt, Ti, Ru, Fe, Cr, Mo, and Ta were used. The wafers were bonded at room temperature over the entire bonded area (1 or 2 in. wafers of either Si or SiO2) using these metal films. Transmission electron microscopic cross-section images revealed that complete crystalline grains were formed across the original surfaces of the films, probably because of recrystallization occurring at the bonded interface when Al-Al, Ag-Ag, Au-Au, Cu-Cu, and Ti-Ti nanocrystalline films were bonded. A clear interface corresponding closely to the original film surface was visible in the bonded Pt-Pt films. However, fcc-(111) lattices were formed continuously across the films' original surfaces. A thin amorphous layer was formed at the interfaces of Cr-Cr, Fe-Fe, and Ta-Ta bonded films. Experimental results revealed that the two films' bonded structure was related closely to the self-diffusion coefficients of the metals used for bonding. A high atomic diffusion coefficient at the grain boundaries and film surfaces is likely to have enabled bonding at room temperature. Moreover, results obtained using Cu-Cu, Al-Al, Ti-Ti, Cr-Cr, and Ta-Ta films demonstrated that the wafers were bonded even with only 0.2-nm-thick films on both sides. Bonding films of different materials was also achieved, e. g., Ta-Cu films. The bonding technique described herein is promising for use with bonding wafers to fabricate new thin film devices and microelectromechanical systems. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3437515]
Thermally induced switching field distribution of a single CoPt dot in a large array 査読有り

J. B. C. Engelen, M. Delalande, A. J. le Febre, T. Bolhuis, T. Shimatsu, N. Kikuchi, L. Abelmann, J. C. Lodder

NANOTECHNOLOGY　21　(3)　035703(1-7)　2010年1月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/0957-4484/21/3/035703 　

ISSN：0957-4484

eISSN：1361-6528

詳細を見る詳細を閉じる

Magnetic dot arrays with perpendicular magnetic anisotropy were fabricated by patterning Co80Pt20-alloy continuous films by means of laser interference lithography. As commonly seen in large dot arrays, there is a large difference in the switching field between dots. Here we investigate the origin of this large switching field distribution, by using the anomalous Hall effect (AHE). The high sensitivity of the AHE permits us to measure the magnetic reversal of individual dots in an array of 80 dots with a diameter of 180 nm. By taking 1000 hysteresis loops we reveal the thermally induced switching field distribution SFDT of individual dots inside the array. The SFDT of the first and last switching dots were fitted to an Arrhenius model, and a clear difference in switching volume and magnetic anisotropy was observed between dots switching at low and high fields.
Room Temperature Bonding of Wafers with Thin Nanocrystalline Metal Films 招待有り査読有り

T. Shimatsu, M. Uomoto

SEMICONDUCTOR WAFER BONDING 11: SCIENCE, TECHNOLOGY, AND APPLICATIONS - IN HONOR OF ULRICH GOSELE　33　(4)　61-72　2010年
出版者・発行元：ELECTROCHEMICAL SOC INC
DOI： 10.1149/1.3483494 　

ISSN：1938-5862

詳細を見る詳細を閉じる

Room temperature bonding between two flat wafers using thin metal films was studied. Thin nanocrystalline metal films (0.2-20 nm thick) were fabricated on two flat wafers' surfaces using sputter deposition. Bonding of the two metal films on the wafers was accomplished immediately after film deposition in vacuum. The wafers were bonded at room temperature over the entire bonded area using metal films of 16 kinds including W films. The two films' bonded structure was related closely to the self-diffusion coefficients of the metal films. The very high atomic diffusion coefficient at the grain boundaries and film surfaces is likely to have enabled bonding at room temperature. The wafers were bonded even with films of 0.2 nm thickness on each side. The potential of the bonding for applications to device fabrication is examined. Moreover, bonding in air using noble metal films is examined according to experimental results.
Atomic Diffusion Bonding of Wafers with Thin Nanocrystalline Metal Films

T. Shimatsu, M. Uomoto

Proceedings of 2010 2nd IEEE International Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2010　273　2010年1月

詳細を見る詳細を閉じる

LTB-3D 2010
Magnetic anisotropy of L1(1)-type (Co1-XMX)(50)Pt-50 (M:Ni, Fe, Cr, Mn) and Co-50(Pt1-XPdX)(50) ordered alloy perpendicular films 査読有り

H. Kataoka, H. Sato, T. Shimatsu, S. Okamoto, O. Kitakami, H. Aoi

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　(10)　102002(4pp)　2010年
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/200/10/102002 　

ISSN：1742-6588

詳細を見る詳細を閉じる

We substituted 3d transition elements M (M=Ni, Fe, Cr, and Mn) for some of the Co, or Pd for some of the Pt, in L1(1)-type Co50Pt50 ordered alloy perpendicular films, and studied magnetic and structural properties. Films were fabricated at a substrate temperature of 360 degrees C using ultra-high vacuum (UHV) sputter film deposition. The order parameter S was almost a constant of about 0.5 when Ni was substituted for some of the Co. The uniaxial magnetic anisotropy K-u and the saturation magnetization, M-s, decreased as the Ni content increased, however, K-u maintained a relatively large value of 1.8x10(7) erg/cm(3) (M-s=570 emu/cm(3)) even for a Co20Ni30Pt50 composition. In the substitutions of Fe for some of the Co, or Pd for some of the Pt, no significant variation in M-s was observed, however, the rate of decrease of K-u on increasing the Fe or Pd content was larger than when Ni was substituted. The substitution of Cr or Mn for some Co resulted in significant reductions in S, M-s and K-u. Experimental results showed the potential of Co-Ni-Pt ordered films for use in data storage applications, due to their very high K-u potential, relatively low M-s, the relatively low fabrication temperature, and good controllability of the grain orientation.
Nucleation size of hcp-CoPt dot arrays characterized by time dependence of coercivity 査読有り

N. Kikuchi, K. Mitsuzuka, T. Shimatsu, O. Kitakami, H. Aoi

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　(10)　102003(4pp)　2010年
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/200/10/102003 　

ISSN：1742-6588

詳細を見る詳細を閉じる

The magnetization reversal process for dot arrays is likely to start from a nucleation followed by propagation process. In this study, we estimated the nucleation diameter D-n for dot arrays made from thin hcp-CoPt perpendicular films (thickness delta=3 nm) and Co/Pt multilayered films (delta=9 nm), respectively. The dot diameter, D, was varied from 30 to 200 nm for CoPt dot arrays, and from 40 to 80 nm for Co/Pt dot arrays. The remanence coercivity was measured at measurement times t' = 10(3) s and 10(-5) s (pulse field), and defined as H-r and H-r(P). The energy barrier Delta E was evaluated by fitting H-r and H-r(P) to Sharrock's equation. The value of D-n was estimated from Delta E, delta and the effective magnetic anisotropy of dot arrays including the demagnetizing energy due to the dot shape K-u(eff). D-n was independent of D in both series of dot arrays, and about 17 nm for CoPt dot arrays and about 11 nm for Co/Pt dot arrays. These values were close to both the grain size and the exchange length of these films.
Remanence coercivity of dot arrays of hcp-CoPt perpendicular films 査読有り

K. Mitsuzuka, T. Shimatsu, N. Kikuchi, S. Okamoto, H. Aoi, O. Kitakami

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　(10)　102005(4pp)　2010年
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/200/10/102005 　

ISSN：1742-6588

詳細を見る詳細を閉じる

The remanence coercivity, H(r), of hcp-CoPt dot arrays with various dot thicknesses, delta, (3 and 10 nm) and Pt content (20-30at%) were experimentally investigated as a function of the dot diameter, D (30-400 nm). All dot arrays showed a single domain state, even after removal of an applied field equal to H(r). The angular dependence of H(r) for the dot arrays indicated coherent rotation of the magnetization during nucleation. H(r) increased as D decreased in all series of dot arrays with various delta and Pt content. Assuming that the nucleation field of a dot is determined by the switching field of a grain having the smallest switching field, we calculated the value of nucleation field H(n)(cal) taking account of the c-axis distribution and the distribution of the demagnetizing field in the dot. The values of H(r) obtained experimentally are in good agreement with those of H(n)(cal), taking account of thermal agitation of magnetization. This result suggested that the reversal process of hcp-CoPt dot arrays starts from a nucleation at the center of the dot followed by a propagation process.
Magnetic and structural properties of L1(1) type CoPt-C ordered alloy perpendicular films as a function of C content 査読有り

T. Shimatsu, H. Sato, H. Kataoka, S. Okamoto, O. Kitakami, H. Aoi

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　(10)　102008(4pp)　2010年
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/200/10/102008 　

ISSN：1742-6588

詳細を見る詳細を閉じる

Magnetic and structural properties of L1(1) type (Co0.5Pt0.5)(100-X)-C-X ordered alloy perpendicular films, fabricated on 2.5 inch size glass disks by sputter deposition, were examined as a function of C content, X. L1(1) type Co0.5Pt0.5-C polycrystalline films (10 nm thickness), with < 111 > axis (the easy axis) perpendicular to the film plane, were successfully fabricated even for a 30 vol% C content. Structural analysis indicated the segregation of C to the grain boundaries. Uniaxial magnetic anisotropy, K-u, of Co0.5Pt0.5 films without C addition was relatively low, about 1.5x10(7) erg/cm(3) under the present deposition conditions. However, the addition of 5 vol.% C to Co-Pt films enhanced the ordering, resulting in an increase in K-u to around 2.5 x10(7) erg/cm(3). A further increase in C content reduced K-u; however, K-u maintained a relatively large value of about 1.8x10(7) erg/cm(3) even for a 20vol% C content, without degrading the easy axis orientation perpendicular to the film plane. Experimental results demonstrated the potential of the L1(1) type Co0.5Pt0.5-C films for use in granular media applications, due to their very high K-u, the relatively low fabrication temperature, and good controllability of the grain orientation.
スタティックテスタによるＢＰＭ記録再生特性の基礎検討

青井基, 嵯峨秀樹, 竜野良亮, 白幡一樹, 三塚要, 三浦健司, 島津武仁, 村岡裕明

電子情報通信学会技術研究報告 MR　109　(328)　13-18　2009年12月3日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.33.57.0_13 　

詳細を見る詳細を閉じる

MR2009-39
Bistability Condition of Circular Nanomagnet 査読有り

Osamu Kitakami, Satoshi Okamoto, Nobuaki Kikuchi, Takehito Shimatsu, Kaname Mitsuzuka, Hajime Aoi

APPLIED PHYSICS EXPRESS　2　(12)　123002(1-3)　2009年12月
出版者・発行元：JAPAN SOCIETY APPLIED PHYSICS
DOI： 10.1143/APEX.2.123002 　

ISSN：1882-0778

詳細を見る詳細を閉じる

We have examined the bistability condition of a circular magnetic dot by extending Thiele's bubble domain theory for an infinite continuous film to a finite one, and have found that the dot is always bistable at least when its diameter is D <= 4 I, where I is the characteristic length given by I = sigma(w)/4 pi M(s)(2) (sigma(w): wall energy per unit area, M(s): saturation magnetization). This domain theory naturally explains the dot size dependence of the nucleation field without any assumptions. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.123002
Magnetic anisotropy of epitaxially grown Co and its alloy thin films 査読有り

J-J Wang, T. Sakurai, K. Oikawa, K. Ishida, N. Kikuchi, S. Okamoto, H. Sato, T. Shimatsu, O. Kitakami

JOURNAL OF PHYSICS-CONDENSED MATTER　21　(18)　185008(1-6)　2009年5月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.1088/0953-8984/21/18/185008 　

ISSN：0953-8984

詳細を見る詳細を閉じる

We have performed a systematic study on the correlation between magnetic anisotropy energy (MAE) and crystal structures, such as lattice parameters, stacking fault densities, lattice strain, and so on, for epitaxially grown Co, Co-Pt, and Co-Pd alloy thin films, and have found that the MAE strongly depends on the axial ratio c/a of the hcp crystal lattice. As the c/a of hcp Co decreases down to similar to 1.61 which is smaller than 1.622 for bulk Co, the MAE becomes significantly enhanced up to similar to 10(6) J m(-3). Similar trends have also been verified for hcp Co-Pt and -Pd. These results, which are qualitatively consistent with the classic single-ion anisotropy model and the recent first principles calculation, suggest a new effective way to control the MAE of magnetic thin films.
Magnetic properties of thin hard/soft-stacked dot arrays with a large uniaxial magnetic anisotropy 査読有り

K. Mitsuzuka, T. Shimatsu, N. Kikuchi, O. Kitakami, H. Muraoka, H. Aoi

JOURNAL OF APPLIED PHYSICS　105　(7)　07C103(1-3)　2009年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3072014 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Magnetic properties of hard/soft stacked dot arrays consisting of thin Co/Pt superlattice hard layers (3.6 nm in thickness, uniaxial magnetic anisotropy, K(u) = 1.3 X 10(7) erg/cm(3)) and Co soft layers, with dot diameters of 30-40 nm, were investigated as functions of Co soft layer thickness and the interfacial exchange coupling between the hard and soft layers. Pt was used as the control layer of the interfacial exchange coupling, and Co soft layers were sandwiched with Pt layers to induce surface anisotropy on the Co soft layers. The remanence coercivity, H(r), was 2.7 kOe for Co/Pt(3.6 nm)/Co(4nm) stacked dot arrays and 3.2 kOe for Co/Pt(3.6 nm)/Pt(1.2 nm)/Co(3 nm) stacked dot arrays, and these values were less than half that of single hard layer dot arrays (7.1 kOe). H(r) was nearly constant in the phi range from 0 degrees to about 45 degrees (phi is the applied field angle from the easy axis), and increased significantly as phi increased further, as theoretically predicted. Hard/soft dot arrays maintained a relatively large K(u) due to the surface anisotropy of the Co soft layers. It was suggested that the ratio of magnetic energy to the thermal energy, K(u)(eff)V/kT, for Co/Pt(3.6 nm)/Pt(1.2 nm)/Co (3 nm) hard/soft dot arrays was 1.5 times larger than that for Co/Pt(3.6 nm) single dot arrays because of the relatively large Ku. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3072014]
Dot arrays of L1(1) type Co-Pt ordered alloy perpendicular films 査読有り

T. Shimatsu, H. Sato, K. Mitsuzuka, H. Kataoka, H. Aoi, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　105　(7)　07C109(1-3)　2009年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3068539 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Magnetic properties of dot arrays of L1(1) type Co-Pt ordered alloy perpendicular films were studied. L1(1)-Co-Pt films with a large uniaxial magnetic anisotropy K-u of the order of 10(7) erg/cm(3) were fabricated at a substrate temperature of 360 degrees C using ultrahigh vacuum sputter film deposition. Dot patterns with dot diameters of 70-200 nm were made using high resolution e-beam lithography and reactive ion etching (RIE). The values of Ku were measured by the GST method using the Anomalous Hall Effect; we observed the averaged signals of 6000 dots. The values of K-u for dot arrays of 10-nm-thick L1(1)-Co50Pt50 films deposited on MgO(111) substrates (single crystal films) and glass disks (polycrystalline films) were nearly the same as those of the original films independent of D, indicating no significant etching damage by the RIE process. Magnetic force microscopy images revealed that all dots were single domains in the present D region. The coercivity H-c of the dot arrays was 25.0 kOe [MgO(111) substrate, D=70 nm] and 14.3 kOe (glass disks, D=80 nm). The switching field distribution sigma/H-c was relatively small, sigma/H-c=0.15, even for dot arrays fabricated on glass disks, indicating the homogeneous formation of a L1(1) type ordered structure in the Co50Pt50 layers. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3068539]
Fabrication of L1(1)-type (Co-Ni)-Pt ordered alloy films by sputter deposition 査読有り

H. Sato, T. Shimatsu, H. Kataoka, H. Aoi, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　105　(7)　07B726(1-3)　2009年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.3072758 　

ISSN：0021-8979

詳細を見る詳細を閉じる

L1(1)-type (Co-Ni)-Pt ordered alloy perpendicular films were successfully fabricated on MgO(111) single crystal substrates using ultrahigh vacuum sputter film deposition; the addition of Ni to Co-Pt was effective to reduce saturation magnetization, M-s, maintaining a large K-u of the order of 10(7) erg/cm(3). L1(1)-type ordered structures, with the < 111 > direction (easy axis of magnetization) perpendicular to the films, were successfully fabricated at a substrate temperature of 360 C in a wide composition range with Co content less than 60 at. %. The order parameter, S, was almost a constant of about 0.5 in the stoichiometric composition of (Co1-XNiX)(50)Pt-50, independent of Ni content, X. L1(1)-type Co-Ni-Pt perpendicular films having a large K-u of (1-2.5) x 10(7) erg/cm(3) and a relatively low M-s of 400-700 emu/cm(3) were successfully fabricated in the composition range of 10-35 at. % Co, 20-55 at. % Ni, and bal. Pt. K-u should increase further with enhanced ordering. Experimental results demonstrated the potential of these Co-Ni-Pt ordered films for use in data storage applications due to very high K-u potential comparable to L1(0)-type Fe50Pt50 films, relatively low M-s, the relatively low fabrication temperature, and good controllability of the grain orientation. (c) 2009 American Institute of Physics. [DOI: 10.1063/1.3072758]
記録材料のナノサイズ領域における磁化挙動の検討

菊池伸明, 岡本聡, 北上修, 島津武仁, 佐藤英夫, 三塚要, 青井基

日本磁気学会第165回研究会資料　2009年3月
Magnetic behavior of single nanostructured magnet 招待有り査読有り

O. Kitakami, S. Okamoto, N. Kikuchi, T. Shimatsu, H. Sato, H. Aoi

Journal of Physics: Conference Series　165　012029(1-6)　2009年
出版者・発行元：Institute of Physics Publishing
DOI： 10.1088/1742-6596/165/1/012029 　

ISSN：1742-6596 1742-6588

詳細を見る詳細を閉じる

For future advancement in magnetic and spin electronic devices, it is essential to understand the magnetic behaviour and spin dynamics of a single nanomagnet. However, no effective method has been available for detection of such extremely small magnetic moment. To overcome this difficulty, we have newly developed a highly sensitive magnetic detection technique utilizing the anomalous Hall effect (AHE). This technique has systematically revealed the magnetic behaviors of various magnetic materials in the nanoscale regime. In this article, we demonstrate how single nanomagnets of L10 FePt and Co/Pt multilayers behave depending on their size, especially focusing on the magnetization reversal process and the bistability condition necessary for digital memory use. © 2009 IOP Publishing Ltd.
Magnetization behavior of nanomagnets for patterned media application 招待有り査読有り

S. Okamoto, N. Kikuchi, T. Kato, O. Kitakami, K. Mitsuzuka, T. Shimatsu, H. Muraoka, H. Aoi, J. C. Lodder

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　320　(22)　2874-2879　2008年11月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/j.jmmm.2008.07.034 　

ISSN：0304-8853

詳細を見る詳細を閉じる

Bit patterned media (BPM) which utilize each magnetic nanostructured dot as one recorded bit has attracted much interest as a promising candidate for future high-density magnetic recording. In this study, the magnetization reversal behaviors of nanostructured L1(0)-FePt, Co/Pt multilayer (ML), and CoPt/Ru dots are investigated. For Co/Pt and CoPt/Ru nanodots, the bi-stable state is maintained in a very wide size range up to several hundred nm, and the magnetization reversal is dominated by the nucleation of a small reversed nucleus with the dimension of domain wall width. On the other hand, the critical size for the bi-stability of L1(0)-FePt is about 60 nm, and its magnetization reversal proceeds via domain wall displacement even for such a small dot size. These reversal behaviors, depending on the magnetic materials, might be attributed to the difference in structural inhomogeneity, such as defects. In addition to the magnetic properties, the structural uniformity of the material could be crucial for the BPM application. (C) 2008 Elsevier B. V. All rights reserved.
Thermal stability and switching field of hard/soft-stacked perpendicular media 査読有り

T. Shimatsu, N. Asakura, Y. Inaba, K. Kudo, A. Sato, H. Muraoka, H. Aoi, S. Okamoto, O. Kitakami

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　320　(22)　3088-3091　2008年11月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/j.jmmm.2008.08.020 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The time dependence of remanence coercivity and thermal stability were investigated for hard/soft-stacked media consisting of a magnetically hard granular layer underneath a very thin soft layer with a large saturation magnetization, M(s). The values of remanence coercivity at measurement times t' = 10(3) and 10(-5) s (pulse field) were measured, and defined as H(r) and H(r)(P). The remanence coercivity on the recording time scale, H(r) ( 1 ns), and the energy barrier, Delta E/kT, were evaluated by fitting H(r) and H(r)(P) to Sharrock's equation taking into account the power law variation of the energy barrier, n. The value of H(r) (1 ns) for a (Co-Pt)-SiO(2) ( 9 nm)/Co-SiO(2) (2 nm) stacked medium with an interfacial coupling control layer was about 9 kOe, which was less than half of that of a (Co-Pt)-SiO(2) (9 nm) conventional medium (21.3 kOe). The value of Delta E/kT for the stacked medium was about 111 (n = 0.7), and was not significantly different from the conventional medium. Moreover, no significant difference in the rate of decrease of Hr with increasing temperature was observed between media with and without interlayers. These results indicate that the use of a thin soft layer with high Ms was effective at significantly reducing Hr with no notable change in thermal stability. (C) 2008 Elsevier B. V. All rights reserved.
大きな垂直磁気異方性を有する磁性薄膜の形成とビット・パターン媒体への応用

島津武仁, 佐藤英夫, 青井基, 岡本聡, 北上修

応用物理学会応用電子物性分科会会誌　14　(4)　113-118　2008年10月
スパッタリング法による L11型Co-Pt規則化合金膜の作製とその磁気特性査読有り

島津武仁, 佐藤英夫, 青井基, 村岡裕明, 岡本聡, 北上修

まぐね　3　(6)　271-276　2008年6月
出版者・発行元：日本磁気学会
ISSN：1880-7208

詳細を見る詳細を閉じる

トピックス
Fabrication of L1(1) type Co-Pt ordered alloy films by sputter deposition 査読有り

H. Sato, T. Shimatsu, Y. Okazaki, H. Muraoka, H. Aoi, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　103　(7)　07E114(1-3)　2008年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2830097 　

ISSN：0021-8979

詳細を見る詳細を閉じる

L1(1) type Co-Pt ordered alloy films with a large uniaxial magnetic anisotropy, K(u), of the order of 10(7) erg/cm(3) were successfully fabricated at relatively low substrate temperatures of 270-390 degrees C using ultrahigh vacuum sputter film deposition. L1(1) type ordered Co-Pt films, with the < 111 > direction (easy axis of magnetization) perpendicular to the film plane, were fabricated on MgO(111) single crystal substrates and glass disks. The ordered structure was formed in a wide Pt content region of 40-75 at. %, and K(u) showed a maximum at around 50 at. % Pt content. The values of the order parameter S and K(u) for L1(1) type Co(50)Pt(50) films increased as the substrate temperature T(s), increased. K(u) reached about 3.7x10(7) erg/cm(3) (S=0.54) at T(s)=360 degrees C for the single crystal films deposited on MgO(111) substrates, indicating a potential increase in K(u) by enhancing the ordering. The values of K(u) for polycrystalline films deposited on glass disks were smaller than those for the single crystal films on MgO(111) substrates, however, K(u) reached 1.9 x 10(7) erg/cm(3) at T(s)=360 degrees C. The experimental results demonstrate the potential of L1(1) type Co(50)Pt(50) films for use in data storage applications, because of their very high K(u), comparable to L1(0) type Fe(50)Pt(50) films, the relatively low fabrication temperature, and good controllability of the grain orientation. (C) 2008 American Institute of Physics.
Magnetic properties of Co-Pt/Co hard/soft stacked dot arrays 査読有り

K. Mitsuzuka, T. Shimatsu, H. Muraoka, H. Aoi, N. Kikuchi, O. Kitakami

JOURNAL OF APPLIED PHYSICS　103　(7)　07C504(1-3)　2008年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2833308 　

ISSN：0021-8979

詳細を見る詳細を閉じる

The magnetic properties of Co(80)Pt(20)(10 nm)/Co(0,3,5 nm) hard/soft stacked dot arrays with dot diameters D of about 50 nm were studied. Co-Pt films were deposited on Ru (001) seed layers, resulting in a large uniaxial magnetic anisotropy K(u) with the c axis perpendicular to the film plane. Dot patterns were formed using high resolution e-beam lithography and reactive ion etching. Magnetic force microscopy images revealed that all dot arrays showed a single domain state, even after removal of an applied field equal to the coercivity. The remanence coercivity H(r) decreased from 9.1 to 6.9 kOe as the Co layer thickness increased from 0 to 5 nm, indicating that the hard/soft stacked structure was effective at reducing the switching field, as theoretically predicted. The applied field angular dependence of H(r) for 10-nm-thick Co-Pt dot arrays was in good agreement with calculations based on the Stoner-Wohlfarth model, H(S-W) indicating coherent rotation of the magnetization during nucleation. Moreover, it was confirmed that the hard/soft stacked structure reduced the angular variation of H(r). (c) 2008 American Institute of Physics.
Uniaxial magnetic anisotropy in Co and Co-Pt based perpendicular films in relation to lattice deformation 査読有り

T. Shimatsu, Y. Okazaki, H. Sato, H. Muraoka, H. Aoi, T. Sakurai, S. Okamoto, O. Kitakami, S. Tanii, A. Sakuma

JOURNAL OF APPLIED PHYSICS　103　(7)　07F524(1-3)　2008年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2835448 　

ISSN：0021-8979

詳細を見る詳細を閉じる

The relationship between uniaxial magnetic anisotropy K(u) and lattice deformation was investigated for Co-Pt and Co perpendicular films and compared with theoretical results. A study of Co(100-x)Pt(x)/Ru perpendicular films (x=10,14,20) of various thickness showed that K(u) increased as the c/a ratio of the hcp Co-Pt lattice decreased, and the increase of K(u) for a 1% reduction of c/a was (8-10)x10(6) erg/cm(3). The c/a reduction was accompanied by an increase of the lattice volume V(lattice) of about 2%. An examination of Co(75)Pt(25) films deposited on various seed layer materials showed almost the same relationship between the value of K(u), the c/a ratio, and V(lattice). Moreover, the rate of increase of K(u) on reducing c/a for single crystal Co perpendicular films was nearly the same as for the Co-Pt films. A theoretical calculation of K(u) based on the linear muffin-tin orbital method in the atomic-sphere approximation revealed that both a decrease in the c/a ratio and an increase in V(lattice) enhance the K(u) value of hcp-Co. The theoretical evaluation was qualitatively in good agreement with the experimental results, although the rate of increase of K(u) evaluated experimentally was three to four times larger than the theoretical calculation.
Magnetization behavior of nanomagnets for patterned media application

岡本聡, 菊池伸明, 北上修, 島津武仁

電子情報通信学会技術研究報告 MR　107　(324)　7-12　2007年11月9日

詳細を見る詳細を閉じる

MR2007-27
Microstructure, magnetic properties and their seed layer thickness dependences of granular CoPtCr-SiO2 perpendicular recording media 査読有り

Xiao Chun-Tao, Inaba Yuki, Shimatsu Takehito, Muraoka Hiroaki

SOLID STATE COMMUNICATIONS　144　(1-2)　58-60　2007年10月
出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD
DOI： 10.1016/j.ssc.2007.07.014 　

ISSN：0038-1098

詳細を見る詳細を閉じる

[(Co90Cr10)(85)Pt-15](89.8)-[SiO2](10.2) granular films were prepared by using co-sputtering methods, with Ru as a seed layer. Influences of Ru thickness on microstructure and magnetic properties of CoPtCr-SiO2 magnetic layer were investigated. It was found that the seed layer obviously effected the grain isolation, c-axis distribution and magnetic parameters. Ru seed layer with suitable thickness is very helpful for achievement of high anisotropy, proper coercivity and high squareness. The anisotropy energy of magnetic layer can be as high as 5 x 10(6) erg/cm(3) or more even with a thin Ru layer, promising good thermal stability. It should be noted that Ru layer markedly enhanced the isolation of CoPtCr grains, corresponding the increase of coercivity and the decrease of loop slope. Moreover, it was also revealed that it was relatively easy for the CoPtCr grains to oriented normal to the film plane even with a Ru seed layer as thin as 3 nm. (C) 2007 Published by Elsevier Ltd.
Pt content dependence of the switching field distributions of CoPtCr-SiO2 perpendicular media characterized by subtracting the effect of thermal agitation 査読有り

T. Shimatsu, T. Kondo, K. Mitsuzuka, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　43　(6)　2091-2093　2007年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2007.892586 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The switching field distributions (SFD) of CoPtCr-SiO2 perpendicular media as a function of Pt content were characterized by subtracting the effect of thermal agitation, and discussed in relation to the microstructure. DC demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of similar to 10 Oe/s and similar to 10(8) Oe/s. We estimated the width of SFD, Delta SFD, from the difference between the DCD and M-DCD curves, and defined them as Delta H-r/H-r (at similar to 10 Oe/s) and Delta H-r(P)/H-r(P) (at similar to 10(8) Oe/s). The values of Delta SFD characterized by subtracting the effect of thermal agitation, Delta H-0/H-0, were nearly half those of Delta H-r/H-r for 10-nm-thick media. Delta H-0/H-0 was about 0.10 at 10 at%Pt content, and increased as the Pt content increased, reaching 0.17 at 30 at%Pt content. The increase in Delta H-0/H-0 was probably caused by an increase in the stacking fault density and the formation of fcc layers in the hcp CoPtCr lattice. A simple calculation based on the coherent switching of magnetization revealed that the c-axis distribution results in Delta H-0/H-0 of about 0.08, independent of Pt content. These results suggest that the Delta SFD due to the grain-to-grain anisotropy field variation was small, only 0.02-0.03.
Recording resolution and writability for (Co-Pt)-SiO2/Co-SiO2 hard/soft-stacked granular perpendicular media 査読有り

T. Shimatsu, Y. Inaba, S. Watanabe, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　43　(6)　2103-2105　2007年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2007.892539 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The magnetic properties and recording performance of hard/soft stacked media consisting of a magnetically hard 9-nm-thick (CoPt)-SiO2 layer underneath a thin (2-3 nm) soft granular layer were studied. Experimental results indicated that an increase in the mean value of saturation magnetization of the soft layer (M-s(soft)) was very effective at improving the recording resolution D-50 due to an increase in the slope of magnetization curve alpha. The use of a Co-SiO2 layer, which has the highest (M-s(soft)) in the present study, resulted in the highest D-50 value. It is likely that the increase in alpha was mainly caused by the demagnetization field in grains due to the difference between M-s(soft)) and the mean value of saturation magnetization of the hard layer, (M-s(hard)). Moreover, it was successfully demonstrated that the magnetization reversal of (Co-Pt)-SiO2/Co-SiO2 stacked media changed systematically as theoretically predicted on reducing the interfacial exchange coupling by using NiFeCr-SiO2 or Pt-SiO2 interlayers. The reduction of remanence coercivity H-r was achieved by controlling the thickness and film composition of the interlayer, moreover, a high-(M-s(soft)) enhanced the H-r reduction. The H-r reduction improved recording writability without degrading D-50, the signal to medium noise ratio SNmR and thermal stability.
Magnetic anisotropy of Co-M-Pt (M = Cr, Mo, Ru, W, Re) perpendicular films denosited on various eed laver materials 査読有り

H. Sato, T. Shimatsu, Y. Okazaki, O. Kitakami, S. Okamoto, H. Aoi, Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　43　(6)　2106-2108　2007年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2007.892540 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The first and second order uniaxial magnetic anisotropy, K-u1 and K-u2, and the saturation magnetization, M-s, of (Co100-XMX)(100-Y)P-tY perpendicular thin films were examined, in order to improve the magnetic properties of CoCrPt-SiO2 media by replacing Cr with M. Fourteen kinds of M elements were examined, but we mainly focus on films with M = Cr, Mo, Ru, W and Re in this paper, since the other elements significantly reduced K-u1, K-u2, or the K-u/M-s ratio. The use of the M elements, instead of Cr, did not result in any significant increase in the values of K-u1, K-u2, and the K-u/M-s ratio. On the other hand, K-u1 and K-u2 of CoPt binary films had a greater dependence on the seed layer materials used (Ru, Pd, Re, Pt, Au, Ir and Cu). The c/a ratio of the hep-CoPt lattice varied significantly with the seed layer materials used probably due to the epitaxial growth of CoPt. K-u1 decreased and K-u2 increased as the c/a ratio increased. The use of specific seed layer materials was more effective at controlling the magnetic anisotropy of CoPt based perpendicular thin films, rather than the addition of M element to the CoPt.
Switching field and thermal stability of CoPt/Ru dot arrays with various thicknesses 査読有り

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Aoi, H. Muraoka, J. C. Lodder

IEEE TRANSACTIONS ON MAGNETICS　43　(6)　2160-2162　2007年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2007.893129 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The switching fields and thermal stability of CoPt/Ru dot arrays with various dot thickness delta (5-20 nm) were experimentally investigated as a function of the dot diameter, D, (130-300 nm). All dot arrays showed a single domain state, even after removal of an applied field equal to the remanence coercivity H-r. The angular dependence of H-r for the dot arrays indicated coherent rotation of the magnetization during nucleation. We estimated the values of the "intrinsic" remanence coercivity H-o obtained by subtracting the effect of thermal agitation on the magnetization and the stabilizing energy barrier to nucleation E-o / (k(B)T). The variation in H-o as a function of delta and D was qualitatively in good agreement with that of the effective anisotropy field at the dot center H-k(eff) (r = 0), calculated taking account of the demagnetizing field in the dots. The ratio of H-o to H-k(eff) (r = 0) for the dot arrays with delta = 10 nm increased from 0.53 to 0.70 as D decreased from 300 to 140 nm, and no significant difference in the H-o / H-k(eff) (r = 0) ratio due to the difference in delta was observed. On the other hand, E-o / (k(B)T) decreased as delta decreased. E-o / (k(B)T) increased slightly as D decreased, but, was not so sensitive to D over the present D range.
Large uniaxial magnetic anisotropy of Co-Pt perpendicular films induced by lattice deformation 査読有り

T. Shimatsu, Y. Okazaki, H. Sato, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　43　(6)　2995-2997　2007年6月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2007.893126 　

ISSN：0018-9464

詳細を見る詳細を閉じる

A study of the thickness dependence of the uniaxial magnetic anisotropy K-u of Co-Pt perpendicular films deposited on Ru seed layers was extended over a wide range of Pt content from 10 to 30 at%, to further investigate the origin of the significant increase in K-u on reducing the film thickness, which was previously reported for Co-80 Pt-20 /Ru films. K-u increased significantly as the thickness decreased in all series (if films with various Pt content. The rate of increase of K-u with reducing thickness became increasingly large as the Pt content decreased. It should be noted that the K-u of 2-nm-thick films was an almost constant 2 x 10(7) erg/cm(3) over the range of Pt contents studied, although K-u was maximized at 25-30at%Pt content for films thicker than 5 nm. Experimental results suggest that the increase in K-u on reducing the thickness was mostly related to a reduction of the hcp Co-Pt lattice c/a ratio.
高飽和磁化の薄いソフト層を有するHard/Soft スタック垂直媒体の磁気特性と記録再生特性査読有り

稲葉祐樹, 島津武仁, 渡辺貞幸, 北上修, 岡本聡, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会誌　31　(3)　178-183　2007年5月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.31.178 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The magnetic properties and recording performance of hard/soft-stacked media consisting of a magnetically hard layer (9-10 nm) underneath a very thin soft layer (2 nm) with a large saturation magnetization were investigated. Magnetic energy calculations revealed that reducing the strength of the interfacial exchange coupling between the hard and soft layers reduces the remanence coercivity, Hr. Moreover, an increase in the saturation magnetization of the soft layer <Mssoft> significantly enhances the Hr reduction. It is theoretically predicted that the grain volume of hard (10 nm)/soft (2 nm) stacked media having <Mssoft> of 1000 emu/cm3 could be reduced to about 1/3 that of conventional media whilst maintaining good recording writability and thermal stability. An experimental study of stacked media revealed that the magnetization reversal mechanism changed systematically as a function of the strength of the interfacial exchange coupling, as predicted theoretically. The Hr reduction on adjusting the interfacial coupling reached 22% of that of media consisting of directly coupled hard/soft grains. It was successfully demonstrated that hard/soft-stacked media having thin soft layers with a large <Mssoft> showed better recording writability without degradation of SNmR, recording resolution, or thermal stability.
Microstructure and magnetic properties of granular CoPtCr-SiO2 films on Ru seed layer 査読有り

Chun-Tao Xiao, Yuki Inaba, Takehito Shimatsu, Hiroaki Muraoka

Modern Physics Letters B　21　(6)　357-363　2007年3月10日

DOI： 10.1142/S0217984907012736 　

ISSN：0217-9849

詳細を見る詳細を閉じる

Granular-type [(Co90Cr10)85Pt 15]89.8-[SiO2]10.2 films were prepared by using co-sputtering methods, with Ru as a seed layer. Influences of Ru thickness on the microstructure and magnetic properties of the CoPtCr-SiO2 magnetic layer were investigated. It was found that the seed layer obviously effected the grain isolation, c-axis distribution and magnetic parameters. The Ru seed layer with a suitable thickness is very helpful for achievement of high anisotropy, proper coercivity and high squareness. The anisotropy energy of the magnetic layer can be as high as 5 × 10 6 erg/cm3 or more, even with a thin Ru layer, promising good thermal stability. It was noted that the Ru layer markedly enhanced the isolation of CoPtCr grains, corresponding to the increase of coercivity and the decrease of loop slope. Moreover, it was also revealed that the addition of SiO2 to CoPtCr effectively isolated the CoPtCr grains without disturbing the epitaxial growth of CoPtCr grains on the Ru seed layer. © World Scientific Publishing Company.
Pt content dependence of magnetic properties of CoPt/Ru patterned films 査読有り

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Aoi, H. Muraoka, J. C. Lodder

IEEE TRANSACTIONS ON MAGNETICS　42　(12)　3883-3885　2006年12月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2006.878667 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The magnetic properties of dot arrays made of CoPt/Ru perpendicular films (20 nm thickness) were examined as a function of Pt content. The CoPt dot arrays with a dot size D of 140 nm showed a single domain state, after removal of the applied field equal to H-r. H-r decreased from 5.2 kOe to 3.0 kOe as the Pt content decreased from 20 at % to 14 at %. The angular dependence of H-r for these dot arrays indicated coherent rotation of the magnetization during nucleation. The effective magnetic anisotropy, including the demagnetizing energy due to the dot shape, K-u(eff), decreased as the Pt content decreased, resulting in the H-r reduction. The values of the switching volume for nucleation, V-sw, evaluated from the stabilizing energy barrier E-0, were a few percent of the dot volume. The switching diameter for nucleation, D-sw, increased slightly as the Pt content decreased, which was qualitatively in good agreement with the increase in the exchange length of magnetization. The value of E-0/k(B)T (kB is the Boltzmann constant and T is the absolute temperature) reduced as the Pt content decreased; however, E-0/kBT still had a high of 440 even at 14 at % Pt content. We successfully demonstrated the reduction of H-r for CoPt/Ru patterned films on reducing the Pt content, while simultaneously maintaining a high thermal stability. A calculation based on the experimental results suggested the potential recording density of CoPt/Ru dot arrays used for patterned media to be over 1 Tb/in(2).
Investigation of inclined-pad-type head for cylindrical magnetic storage system 査読有り

H. Yamada, R. Tsuchiyama, H. Kikuchi, T. Shimatsu, I. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　42　(10)　2477-2479　2006年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2006.879573 　

ISSN：0018-9464

詳細を見る詳細を閉じる

A magnetic recording head with an inclined-pad for cylindrical magnetic storage media of 1-in (25.4-mm) diameter using a perpendicular double-layered medium with a CoPtCr-SiO2 recording layer was investigated. The inclined-pad-type head had a trailing pad formed on the trailing edge of the head, which had a single-pole-type (SPT) writer and a giant magnetoresistive (GMR) reader, and an inclined pad formed on the leading edge of the head, which protruded in the thickness direction compared with the trailing pad, for generating an air-bearing force. The inclined-pad-type slider was fabricated and its fly ability was examined with a READ/WRITE tester. Its flying characteristics had almost the same linear velocity dependence as the theoretical design, and are thought to be a potentially valuable component of cylindrical magnetic storage systems.
Switching field distribution of CoPtCr-SiO2 perpendicular recording media obtained by subtracting thermal agitation of magnetization 査読有り

T. Shimatsu, T. Kondo, K. Mitsuzuka, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

IEEE TRANSACTIONS ON MAGNETICS　42　(10)　2384-2386　2006年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2006.878663 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The effect of thermal agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated, and the "intrinsic" SFD caused by variations in the grain-to-grain switching field was determined. DC demagnetizing (DCD) magnetization curves and minor DCD (M-DCD) magnetization curves were measured at applied field-sweep rates of similar to 10 Oe/s and similar to 10(8) Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as Delta H-r/H-r (at similar to 10 Oe/s) and Delta H-r(P)/H-r(P) (at similar to 10(8) Oe/s). The values of Delta H-r/H-r were much larger than those of Delta H-r(P)/H-r(P). Moreover, Delta H-r/H-r. increased faster than Delta H-r(P)/H-r(P) as the thickness decreased, suggesting that the SFD measured at vibrating Sample magnetometer (VSM) time scales is significantly influenced by thermal agitation. The intrinsic SFD estimated using a series of media with various film thicknesses was about 0.14, which was 55%-75% of Delta H-r/H-r for 8-16-nm-thick media. An analysis of the temperature dependence of Delta H-r/H-r supported this conclusion. It is concluded that the SFD measured at VSM time scales is significantly influenced by thermal agitation of the magnetization, and the intrinsic SFD is likely to be nearly half that measured at VSM time scales.
Magnetic properties to optimize the K-u2 effect in perpendicular recording media 査読有り

Hideo Sato, Takehito Shimatsu, Takeshi Kondo, Sadayuki Watanabe, Osamu Kitakami, Satoshi Okamoto, Hajime Aoi, Hiroaki Muraoka, Yoshihisa Nakamura

IEEE TRANSACTIONS ON MAGNETICS　42　(10)　2387-2389　2006年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2006.878668 　

ISSN：0018-9464

詳細を見る詳細を閉じる

We calculated the optimal values of the first- and second-order uniaxial magnetic anisotropy energy terms, K-u1 and K-u2, for thermal stability and writability in perpendicular media which use the K-u2 effect. The magnetic energy barrier Delta E for the remanent state with demagnetizing field 47 pi < M-s > was calculated for various K-u1 and K-u2 values, and we obtained the grain volume V-grain to satisfy Delta EVgrain/kT = 60 for thermal stability (k is the Boltzmann constant, and T the absolute temperature). Moreover, the switching field was calculated assuming a saturation field less than 16 kOe for good writability. The K-u2 term enhances the Delta E in the remanent state of magnetization, without a notable increase in H-s It is concluded that the best value to take advantage of the K-u2 effect is about 500 emu/cm(3), with K-u1 = 5 x 10(6) erg/cm(3) and K-u2 = 2.6 x 10(6) erg/cm(3). The K-u2 term allows (and also the grain size) to be reduced by almost. one-half, compared with a grain without a K-u2 term, while simultaneously achieving good thermal stability and writability.
高速転送シリンダ状磁気ストレージシステム用ヘッドの開発

山田洋, 土山龍司, 菊池弘之, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久, 沼澤順二

電子情報通信学会技術研究報告 MR　106　(142)　35-40　2006年6月29日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2006-16, 通研インポート200703
CoPt/Ru垂直磁化パターン膜の磁気特性と磁化機構

島津武仁, 菊池伸明, J. C. Lodder

日本応用磁気学会第１48回研究会資料　2006年5月18日

詳細を見る詳細を閉じる

2006年5月18日
シリンダ状媒体対応傾斜パッドスライダの浮上安定性に関する検討査読有り

土山龍司, 山田洋, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　30　(3)　361-365　2006年5月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.30.361 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研インポート200703
傾斜パッド型SPT浮上ヘッドによるシリンダ状CoPtCr-SiO2垂直二層膜媒体のR/W特性査読有り

山田洋, 土山龍司, 菊池弘之, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　30　(3)　345-348　2006年5月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.30.345 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研インポート200703
Effect of thermal agitation on the switching field distributions of CoPtCr-SiO2 perpendicular recording media 査読有り

T Shimatsu, T Kondo, K Mitsuzuka, S Watanabe, H Aoi, H Muraoka, Y Nakamura

JOURNAL OF APPLIED PHYSICS　99　(8)　08F905(1-3)　2006年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2172577 　

ISSN：0021-8979

詳細を見る詳細を閉じる

The effect of thermal agitations on the switching field distribution (SFD) of CoPtCr-SiO2 perpendicular media was investigated. Dc demagnetizing (DCD) magnetization curves and minor dc demagnetizing (M-DCD) magnetization curves were measured at applied field sweep rates of similar to 10 and similar to 10(8) Oe/s. We estimated the SFD from the difference between the DCD and M-DCD curves, and defined them as Delta H-r/H-r (at similar to 10 Oe/s) and Delta H-r(P)/H-r(P) (at similar to 10(8) Oe/s). The values of Delta H-r(P)/H-r(P) were found to be 60%-70% of Delta H-r/H-r. The difference between Delta H-r(P)/H-r(P) and Delta H-r/H-r should be caused by thermal agitation of the magnetization. The influence of the distribution of the thermal agitation on SFD was calculated using the distribution of the grain volumes. It is concluded that the SFD measured at vibrating-sample magnetometer (VSM) time scales is significantly influenced by thermal agitation of the magnetization, and reduction of the grain size distribution is the most effective way to reduce the SFD at VSM time scales. (C) 2006 American Institute of Physics.
CoPtCr-SiO2 media with K-u2 magnetic anisotropy term fabricated with Pd seed layers 査読有り

H. Sato, T. Shimatsu, T. Kondo, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　99　(8)　08G907(1-3)　2006年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2166587 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

We tried to enhance the grain isolation of CoPtCr-SiO2 media with Pd seed layers while simultaneously inducing the second energy term of the uniaxial anisotropy, K-u2. The addition of 5%N-2 to the Ar gas used during the deposition of the Pd seed layer was found to reduce the Pd grain size. This structural change in the seed layer enhances the grain isolation of CoPtCr, without degrading the c-axis orientation, while simultaneously inducing a K-u2 component. However, adding N-2 gas to the Pd seed layer increases the CoPtCr grain size to about 10 nm. Moreover, these media have magnetization curves with relatively low squareness, this is related to the appearance of a cone state of magnetization induced by the K-u2 term. Magnetic analysis revealed that, in addition to a reduction of the grain size, a reduction of the saturation magnetization is also necessary to realize practical CoPtCr-SiO2 media, which take advantage of the K-u2 term. (C) 2006 American Institute of Physics.
Large uniaxial magnetic anisotropy by lattice deformation in CoPt/Ru perpendicular films 査読有り

T. Shimatsu, H. Sato, Y. Okazaki, H. Aoi, H. Muraoka, Y. Nakamura, S. Okamoto, O. Kitakami

JOURNAL OF APPLIED PHYSICS　99　(8)　08G908(1-3)　2006年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2167351 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

A large uniaxial magnetic anisotropy K-u of about 2x10(7) erg/cm(3) was obtained in Co-(20-30) at. % Pt perpendicular films deposited on Ru seed layers. The films showed good c-axis orientation perpendicular to the film plane, and no evidence of a Co3Pt-type-ordered structure was found in the X-ray-diffraction patterns. The value of K-u (the sum of the first- and second-order terms of uniaxial anisotropy, K-u1 and K-u2) increased as the thickness of the CoPt layer decreased, and reached about 2x10(7) erg/cm(3) at 2 nm (Co-20 at. % Pt films) or 5 nm (Co-(25-30) at. % Pt films). The ratio of K-u2 to K-u1 was 0.16 in 40 nm films, but reduced to less than 0.03 for thicknesses below 5 nm. The experimental results suggest that, besides the surface anisotropy, the increase in K-u on reducing the thickness is mostly related to the reduction of the hcp-CoPt lattice c/a ratio, probably due to epitaxial growth of CoPt on the Ru seed layer. (C) 2006 American Institute of Physics.
Study of stacking fault effect on magnetic anisotropy of CoPtCr-SiO2 perpendicular media by synchrotron radiation x-ray diffraction 査読有り

T Kubo, Y Kuboki, R Tanuma, A Saito, S Watanabe, T Shimatsu

JOURNAL OF APPLIED PHYSICS　99　(8)　08G911(1-3)　2006年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2172896 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Thin films of CoPtCr and CoPtCr-SiO2, perpendicular magnetic media materials, were investigated by synchrotron radiation grazing-incidence x-ray diffraction. The analysis of diffraction peaks in a reciprocal space provided the variation of stacking faults as functions of Pt content in these materials. It was found that stacking faults start increasing at 15-20 and 25-30 at. % Pt for CoPtCr-SiO2 and CoPtCr films, respectively. These results can well explain the phenomenon whereby the magnetic anisotropy of CoPtCr-SiO2 increases with an increasing Pt content and decreases above 20 at. % Pt, whereas that of CoPtCr increases up to 30 at. % Pt and then decreases. (C) 2006 American Institute of Physics.
Thermal stability and recording writability of hard/soft stacked perpendicular media 査読有り

Y Inaba, T Shimatsu, H Aoi, H Muraoka, Y Nakamura, O Kitakami

JOURNAL OF APPLIED PHYSICS　99　(8)　08G913(1-3)　2006年4月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.2177068 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Magnetic properties and recording performance were studied for hard/soft stacked media consisting of a magnetically hard CoPtCr-SiO2 layer (10 nm thickness) underneath a soft granular layer. Various kinds of soft layers [NiFe(Cr)-SiO2, CoCr-SiO2,...] were used in the present study. Transmission electron microscope images revealed that the grains of the soft layer grew on CoPtCr grains in all kinds of stacked media with SiO2 segregated at the grain boundaries. However, it was revealed that the grain isolation becomes degraded at the film surface when the soft layer was thicker than a critical thickness, and this thickness was about 7 nm for (NiFe/CoPtCr)-SiO2 media. The stacked structure reduced the coercivity, with no significant change in the slope of the magnetization curve. The reduction in dynamic coercivity H-0 reached about 2 kOe for stacked media with 3 nm soft layers, allowing a reduction of the saturation recording current. Furthermore, no significant changes in the signal to media noise ratio SNmR and thermal stability were observed on stacking the soft layer. We demonstrated that hard/soft stacked media with thin soft layers show better recording writability with no notable change in SNmR or thermal stability. (C) 2006 American Institute of Physics.
CoPt/Ruパターン膜の磁化反転機構とスイッチング磁界査読有り

三塚要, 島津武仁, 村岡裕明, N.Kikuchi, J.C.Lodder

日本応用磁気学会誌　30　(2)　100-107　2006年2月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.30.100 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研ＤＢインポート
Large uniaxial magnetic anisotropy in Co100-xPtx/Ru disordered perpendicular films 査読有り

Shimatsu, T, Okazaki, Y, Sato, H.a, Kitakami, O, Okamoto, S, Aoi, H.a, Muraoka, H.a, Nakamura, Y.a

INTERMAG - IEEE Int. Magn. Conf.　4261603　2006年

DOI： 10.1109/INTMAG.2006.375669 　
Magnetization process of high anisotropy CoPt nanosized dots 査読有り

N Kikuchi, R Murillo, JC Lodder, K Mitsuzuka, Shimatsu, I

IEEE TRANSACTIONS ON MAGNETICS　41　(10)　3613-3615　2005年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2005.854784 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Dot arrays with diameter ranging from 80 to 245 nm are made of Co-80 Pt-20 films with large perpendicular anisotropy. Magnetic properties are investigated by detecting the anomalous Hall effect. The all arrays show angular dependence of remanent coercivity similar to coherent rotation. The result shows that reversal process is independent of dot diameter. The energy barrier height of magnetization reversal is estimated as 1.0 x 10(-10) erg for the array consists of 140-nm-diameter dots. From the energy value, the switching volume is estimated as equivalent to the volume of a physical grain in the film. The results indicate that the reversal process starts from a nucleation of a "reversed grain" followed by propagation process.
CoPtCr-SiO2 perpendicular media for high density recording with a high order magnetic anisotropy energy term 査読有り

T Shimatsu, H Sato, T Oikawa, K Mitsuzuka, Y Inaba, O Kitakami, S Okamoto, H Aoi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　41　(10)　3175-3177　2005年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2005.855282 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The first and second order energy terms of uniaxial magnetic anisotropy, K-u1 and K-u2, of CoPtCr-SiO2 perpendicular recording media were studied as a function of film composition and film structure. Moreover, the fabrication of CoPtCr-SiO2 media having adequate values of K-u1 and K-u2 for high recording density was preliminarily studied. An analysis of CoPtCr films with various kinds of seed layer materials revealed that the values of K-u1 and K-u2 varied significantly with the seed layer material used, probably due to epitaxial growth of CoPtCr on the seed layers. K-u2 increased, accompanied by a reduction in K-u1 as the c/a ratio of the hep-CoPtCr lattice increased. Moreover, experimental results suggest that a high stacking-fault density enhances the K-u2 values, especially in the high Pt content region. The addition of SiO2 reduces the total anisotropy, K-u1 + K-u2, but no significant change in the ratio of K-u2/K-u1 was observed. The fabrication of CoPtCr-SiO2 Media with adequate values of K-u1 and K-u2 was successfully demonstrated, although more intensive efforts to enhance grain isolation are required to confirm the advantages conferred by the K-u2 term.
Activation volumes in CoPtCr-SiO2 perpendicular recording media 査読有り

Y Inaba, T Shimatsu, H Muraoka, JD Dutson, K O'Grady

IEEE TRANSACTIONS ON MAGNETICS　41　(10)　3130-3132　2005年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2005.854850 　

ISSN：0018-9464

詳細を見る詳細を閉じる

CoPtCr-SiO2 perpendicular recording media with varying levels of SiO2 were examined by two different methods to determine the activation volume. The first is based on the sweep-rate dependence of the remanence coercivity using Sharrock's equation. The second is based on the measurement of the fluctuation field from time-dependence data, determined using a magneto-optical Kerr effect (MOKE) magnetometer. The values of V-act measured at the coercivity for both methods are almost the same, with the fluctuation field and activation volumes increasing with the SiO2 content. The difference between V-act and the grain volume measured directly from bright-field TEM images decreases as the SiO2 content increases due to the reduction of intergranular exchange coupling. The experimental results indicate that values of V-act obtained from single- and double-layered media are consistent. It was also found that the coercivity and normalized hysteresis loop slope at coercivity varied with SiO2 content, with the coercivity peaking at 8 at % SiO2 (nearly 26 vol% SiO2).
Preliminary study on (CoPtCr/NiFe)-SiO2 hard/soft-stacked perpendicular recording media 査読有り

Y Inaba, T Shimatsu, O Kitakami, H Sato, T Oikawa, H Muraoka, H Aoi, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　41　(10)　3136-3138　2005年10月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2005.854848 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Hard/soft-stacked perpendicular recording media were proposed in order to improve recording writability without notable changes in thermal stability and noise performance. A preliminary study on stacked media consisting of a 10-nm magnetically hard CoPtCr-SiO2 layer underneath a soft NiFe-SiO2 layer (0-4 nm) was performed. Transmission electron microscope images revealed that NiFe/CoPtCr stacked grains were well isolated by SiO2 at grain boundaries, similar to the isolation of single layer CoPtCr-SiO2 media. No change was observed in the slope of the hysteresis loop on stacking the NiFe-SiO2 layer, suggesting there was no significant change in intergranular magnetic coupling. The switching field decreased by 2 kOe as the NiFe-SiO2 layer thickness increased from 0 to 3 nm, without a notable reduction in the stabilizing thermal energy barrier. Moreover, the angular dependence of remanence coercivity indicates that magnetization reversal occurs by coherent rotation in (CoPtCr/NiFe)-SiO2 stacked media as predicted theoretically, and no significant difference in switching mechanism from single layer CoPtCr-SiO2 media was observed. We successfully demonstrated that the hard/soft-stacked media show a better recording writability with no, notable change in signal-to-media-noise ratio or thermal stability.
グラニュラ垂直磁気記録媒体の高密度化に向けて

島津武仁, 北上修, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会第１44回研究会資料　2005年10月
Nanostructure of CoPtCr-SiO2 granular films for magnetic recording media 査読有り

S Fukami, N Tanaka, T Shimatsu, O Kitakatmi

MATERIALS TRANSACTIONS　46　(8)　1802-1806　2005年8月
出版者・発行元：JAPAN INST METALS
DOI： 10.2320/matertrans.46.1802 　

ISSN：1345-9678

eISSN：1347-5320

詳細を見る詳細を閉じる

Structural properties Of CoPtCr-SiO2 magnetic recording films grown on Ru or Pt seed layers prepared by UHV-magnetron sputtering were studied by high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and energy filtered transmission electron microscopy (EFTEM). CoPtCr grown on Ru seed layers together with SiO2 forms a well-isolated structure composed of CoPtCr fine grains of 10 nm diameter surrounded by amorphous SiO2, whereas CoPtCr grown on Pt seed layers together with SiO2 forms a network structure composed of CoPtCr crystal of 5 nm size. These structural features made differences in their magnetic properties. The HRTEM and EFTEM studies revealed that cylindrical crystalline grains composed of CoPtCr and Ru are formed for CoPtCr-SiO2/Ru samples, whereas SiO2 are aggregated around the boundary between relatively large Pt grains and magnetic layers without obstructing the epitaxial growth of CoPtCr on Pt, not resulting in the cylindrical CoPtCr grains. Lattice spacings of CoPtCr grown on Pt with SiO2 are 0.7% expanded in comparison with CoPtCr grown on Pt without SiO2. The EELS studies suggested that Co and Cr atoms are partly oxidized by SiO2 addition for both samples and Cr atoms are more oxidized for CoPtCr-SiO2/Pt samples.
Depth profile of spin and orbital magnetic moments in a subnanometer Pt film on Co 査読有り

M Suzuki, H Muraoka, Y Inaba, H Miyagawa, N Kawamura, T Shimatsu, H Maruyama, N Ishimatsu, Y Isohama, Y Sonobe

PHYSICAL REVIEW B　72　(5)　054430(1-8)　2005年8月
出版者・発行元：AMERICAN PHYSICAL SOC
DOI： 10.1103/PhysRevB.72.054430 　

ISSN：1098-0121

詳細を見る詳細を閉じる

The magnetic properties of a few atomic Pt layers on a 15-nm-thick Co film were studied by x-ray magnetic circular dichroism spectroscopy at the Pt L-2,L-3 edges. The spin and orbital magnetic moments of the Pt 5d electrons were separated using the sum rules, and the depth profiles of these moments were determined as a function of the distance from the Co-Pt interface. A Pt atom has a total magnetic moment of 0.61 mu(B)/atom at the interface, and the moment decreases exponentially with the distance from the interface with a characteristic decay length of 0.41 nm. Four atomic Pt layers near the interface possess 90% of the total magnetization of Pt. The Pt orbital magnetic moment is more than 15% relative to the spin moment and confined to two atomic layers near the interface. The orbital moment was found to be isotropic in the dichroism measurements using external magnetic fields perpendicular and parallel to the film plane. These properties of Pt magnetization are discussed in the context of thermal stability of magnetic recording media covered with a thin Pt overlayer.
CoPt/Ruパターンド膜の磁化機構と熱安定性

島津武仁, 三塚要, 村岡裕明, N. Kikuchi, J. C. Lodder

電子情報通信学会技術研究報告 MR　105　(167)　25-30　2005年7月1日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2005-20
傾斜パッド型ヘッドを用いたCoPtCr-SiO2垂直二層膜シリンダ状媒体の検討査読有り

山田洋, 土山龍司, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　29　(5)　549-552　2005年5月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.29.549 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研ＤＢインポート
K-u2 magnetic anisotropy term of CoPtCr-SiO2 media for high density recording 査読有り

T Shimatsu, H Sato, K Mitsuzuka, T Oikawa, Y Inaba, H Aoi, H Muraoka, Y Nakamura

JOURNAL OF APPLIED PHYSICS　97　(10)　10N111(1-3)　2005年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1851918 　

ISSN：0021-8979

eISSN：1089-7550

詳細を見る詳細を閉じる

Measurements of higher energy term of magnetic anisotropy, K-u2, in CoPtCr-SiO2 perpendicular recording media are described. It was revealed that the values of K-u2 and the first order energy term, K-u1 vary significantly according to the seed layer material used, however, no significant change in the ratio of K-u2/K-u1 was observed on the addition Of SiO2 to CoPtCr films. K-u2 increases and K-u1 decreases as the c/a ratio of the hcp-CoPtCr lattice increases. It is concluded that CoPtCr films have sufficient potential in the values of K-u1 and K-u2 for high density perpendicular media. (c) 2005 American Institute of Physics.
Crystallographic analysis of CoPtCr-SiO2 perpendicular recording media with high anisotropy using synchrotron radiation X-ray diffraction 査読有り

T Kubo, Y Kuboki, M Ohsawa, R Tanuma, A Saito, Oikawa, I, H Uwazumi, T Shimatsu

JOURNAL OF APPLIED PHYSICS　97　(10)　10R510(1-3)　2005年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1855572 　

ISSN：0021-8979

詳細を見る詳細を閉じる

A CoPtCr-SiO2 film is a potential material for high-density perpendicular recording media due to their high magnetic anisotropy constant K-u However, the value of K-u decreases in high levels of Pt content. In this study, this phenomenon was analyzed by synchrotron radiation grazing incidence x-ray diffraction and transmission electron microscopy techniques. Although the CoPtCr-SiO2 films contained almost no fcc phase at 20 at. % Pt or less, it increased remarkably at 30 at. % Pt. This result coincided with the variations of K-u with respect to the Pt content for the CoPtCr-SiO2 films. We consider that the fcc phase formation at Pt content levels in the vicinity of 30 at. % is an influential factor of the K-u reduction. Our techniques proved to be sensitive for the detection of fcc regions in the CoPtCr-SiO2 films. (c) 2005 American Institute of Physics.
CoPtCr-SiO2垂直磁気記録媒体の結晶磁気異方性エネルギーの2次項Ku2と構造査読有り

佐藤英夫, 島津武仁, 三塚要, 及川忠昭, 北上修, 岡本聡, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会誌　29　(4)　427-431　2005年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.29.427 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研ＤＢインポート
Hard/Soft スタック垂直磁気記録媒体の基礎特性査読有り

稲葉祐樹, 島津武仁, 北上修, 佐藤英夫, 及川忠昭, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会誌　29　(3)　239-242　2005年3月
出版者・発行元：公益社団法人日本磁気学会
DOI： 10.3379/jmsjmag.29.239 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研ＤＢインポート
CoPtCr-SiO2/Ru垂直磁気記録媒体のSiO2組成と粒の孤立化査読有り

及川忠昭, 島津武仁, 稲葉祐樹, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　29　(3)　231-234　2005年3月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.29.231 　

ISSN：0285-0192

詳細を見る詳細を閉じる

通研ＤＢインポート
Read/write performance of perpendicular double-layered cylindrical media 査読有り

H Yamada, T Shimatsu, Watanabe, I, R Tsuchiyama, H Aoi, H Muraoka, Y Nakamura

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　287　486-490　2005年2月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/j.jmmm.2004.10.080 　

ISSN：0304-8853

詳細を見る詳細を閉じる

A cylindrical magnetic storage system using perpendicular double-layered media has been developed. CoCrTa/CoZrNb deposited on a rotating cylindrical substrate shows perpendicular anisotropy and magnetic properties, which have almost the same characteristics as conventional disk-media. The fundamental read/write characteristics of perpendicular double-layered cylindrical media were measured using a single-pole-type (SPT) writer with a sliding-contact-type slider and a merged giant magneto-resistive (GMR) reader with a one-pad-type slider designed for use with cylindrical media. Preliminary studies for improving the characteristics of the recording layer are also described. (C) 2004 Elsevier B.V. All rights reserved.
High-potential magnetic anisotropy of CoPtCr-SiO2 perpendicular recording media 招待有り査読有り

T Shimatsu, H Sato, T Oikawa, Y Inaba, O Kitakami, S Okamoto, H Aoi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　41　(2)　566-571　2005年2月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2004.838071 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The magnetic anisotropy of CoPtCr-SiO2 perpendicular recording media, including higher energy terms, was studied as a function of film composition and seed layer materials. All series of CoPtCr films with various Cr content, deposited on Ru seed layers, show maximum values of total anisotropy K. at 25-30 at%Pt. The maximum value for CoPt(Cr = 0) films reaches similar to 15 X 10(6) erg/cm(3). The addition Of SiO2 to the CoPtCr films reduces the grain K., however the grain K. maintains a large value of 8 x 10(6) erg/cm(3) even when 10at% SiO2 is added to (Co90Cr10)(80)Pt-20, for instance, which indicates the high-potential thermal stability. Theoretical calculations for media designs of 400 Gbits/in(2) revealed that the ratio of the high-energy anisotropy term K-u2 to K-u1 (K-u = K-u1 + K-u2) is required to be 0.2-0.35 to enhance the energy barrier for the remanent state, without a notable change in switching field. The films deposited on Ru seed layers were found to show negligibly small K-u2 values, however, the values of K-u1 and Ku(2) vary significantly with the seed layer material used. K-u1 decreases almost linearly as the Ku(2) value increases. It is concluded that CoPtCr films have a sufficient potential in the values of K-u1 and Ku(2) for high-density perpendicular media.
Magnetic moment in the top Pt layer of Co/Pt bilayers 査読有り

M. Suzuki, H. Miyagawa, N. Kawamura, H. Muraoka, Y. Inaba, T. Shimatsu, Y. Sonobe, Y. Isohama, N. Nakamura, N. Ishimatsu, H. Maruyama

Physica Scripta T　T115　580-582　2005年

DOI： 10.1238/Physica.Topical.115a00580 　

ISSN：0281-1847

詳細を見る詳細を閉じる

The magnetic properties of a few atomic Pt layers on a 15nm thick Co film were studied by x-ray magnetic circular dichroism spectroscopy at the Pt L 2,3 edges. The spin and orbital magnetic moments of the Pt 5d electrons were separated using the magneto-optical sum rules. The Pt magnetization profile as a function of distance from the Co-Pt interface was determined using data from a series of films with various Pt thicknesses. This magnetization profile was approximated by an exponential function with a decay length of 0.41nm, which characterizes the effective range of the magnetic coupling between Co and Pt. The total magnetic moment of a Pt atom at the interface was 0.7μB/atom including a 13% orbital moment. This is discussed in the context of the thermal stability of magnetic recording media capped with a thin layer of Pt. © Physica Scripta 2005.
Magnetic moment in the top Pt layer of Co/Pt bilayers 査読有り

Suzuki, M, Miyagawa, H, Kawamura, N, Muraoka, H, Inaba, Y, Shimatsu, T, Sonobe, Y, Isohama, Y, Nakamura, N, Ishimatsu, N

PHYSICA SCRIPTA　T115　580-582　2005年
出版者・発行元：IOP PUBLISHING LTD
ISSN：0031-8949

詳細を見る詳細を閉じる

The magnetic properties of a few atomic Pt layers on a 15 nm thick Co film were studied by X-ray magnetic circular dichroism spectroscopy at the Pt L-2,L-3 edges. The spin and orbital magnetic moments of the Pt 5d electrons were separated using the magneto-optical sum rules. The Pt magnetization pro. le as a function of distance from the Co-Pt interface was determined using data from a series of films with various Pt thicknesses. This magnetization pro. le was approximated by an exponential function with a decay length of 0.41 nm, which characterizes the effective range of the magnetic coupling between Co and Pt. The total magnetic moment of a Pt atom at the interface was 0.7 mu(B)/atom including a 13% orbital moment. This is discussed in the context of the thermal stability of magnetic recording media capped with a thin layer of Pt.
CoPtCr-SiO2 perpendicular media with the high order energy term of magnetic anisotropy for high density recording 査読有り

Shimatsu, T, Sato, H, Oikawa, T, Mitsuzuka, K.a, Inaba, Y, Aoi, H.a, Muraoka, H.a, Nakamura, Y, Kitakami, O, Okannoto, S

Digests Int. Magnet. Conf.　791-791　2005年
日本応用磁気学会第144回研究会資料(2005）招待有り査読有り

島津武仁, 北上修, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会第144回研究会資料　2005年
CoPtCr-SiO2垂直磁気記録媒体の高次の一軸磁気異方性と高密度化招待有り

島津武仁, 北上修, 青井基, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　104　(408)　5-10　2004年10月28日

詳細を見る詳細を閉じる

MR2004-21
高速転送シリンダ状磁気ストレージシステムの開発

山田洋, 島津武仁, 土山龍司, 渡辺功, 青井基, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　104　(330)　19-24　2004年9月30日

詳細を見る詳細を閉じる

MR2004-14
Optimization of the SiO2 content in CoPtCr-SiO2 perpendicular recording media for high-density recording 査読有り

Y Inaba, T Shimatsu, S Oikawa, H Sato, H Aoi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　40　(4)　2486-2488　2004年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2004.832451 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Optimization of the SiO2 content for high-density recording was discussed for {(Co90Cr10)(80)Pt-20}(100-Z0)-{SiO2 }(Z) perpendicular recording media. The grain size D-grain decreases significantly from 8.8 to 5.4 mn as the SiO2 content Z increases from 0 to 14.4; however, no significant difference in c-axis orientation was observed. Magnetocrsytalline anisotropy of grains maintains a large value of nearly 8 x 10(6) erg/cm(3), even at 10 at % SiO2 addition, indicating a high potential of perpendicular anisotropy K-u to resist thermal agitation of magnetization. The coercivity H-c increases significantly as the SiO2 increases, which is coincident with the reduction of the slope of magnetization curve alpha = 4pi(dM/dH) due to the enhancement of grain isolation. The H, shows a maximum at around 11 at % SiO2 (nearly 30 vol % SiO2). A further increase of SiO2 reduces the value of H-c significantly, although the a maintains a constant value of nearly 2, due to thermal agitation of magnetization. The media noise reduces significantly as the SiO2 increases; however, the addition of SiO2 beyond about 13 at % leads to a slight increases in media noise probably due to a significant increase of thermal agitation. The recording resolution D-50 shows a broad maximum of similar to 420 kFCI at around 11 at % SiO2, suggesting that the D50 is related to the media noise performance. Experimental results indicate that there is a tradeoff to be made between the thermal stability and media noise performance as a function Of SiO2 Composition.
Thickness reduction in CoPtCr-SiO2 perpendicular recording media to improve media performance 査読有り

T Shimatsu, T Oikawa, Y Inaba, H Sato, Watanabe, I, H Aoi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　40　(4)　2461-2463　2004年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2004.832359 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Magnetic properties and recording performance of thin CoPtCr-SiO2 media were examined in relation to thermal stability. Magnetic anisotropy K-u of {(Co90Cr10)(80)Pt-20}(89)(SiO2)(11) media maintains a constant value of around 5.5 x 10(6) erg/cm(3), even at film thickness of 4 nm. This K-u value corresponds to the anisotropy energy of the grains K-u(g) calculated by taking account of the volume fraction of about 8 x 10(6) erg/cm(3), indicating a high potential to resist thermal agitation. The high K-u derives a high remanence corcivity H, of similar to 4 kOe, even at film thickness of 8 nm, resulting in a loop squareness of nearly 1. The ratio of magnetic anisotropy energy to thermal energy KuVact/kT maintained a value of more than 70, even at this thickness. The media noise at low recording density increases with decreasing film thickness below 8 run, probably due to the thermal agitation. The recording resolution D-50 showed a broad maximum of similar to 420 kFCI at around this thickness. The reduction in film thickness improves recording resolution; however, it is likely that the large thermal agitation in the thin-film region degrades the recording resolution, resulting in an optimum thickness to show the highest recording resolution.
High perpendicular magnetic anisotropy of CoPtCr/Ru films for granular-type perpendicular media 査読有り

T Shimatsu, H Sato, T Oikawa, Y Inaba, O Kitakami, S Okamoto, H Aoi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　40　(4)　2483-2485　2004年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/tmag.2004.832448 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The perpendicular magnetic anisotropy K-u of CoPtCr films deposited on Ru seed layers is discussed as a function of film composition. Moreover, the change in K-u by the addition of SiO2 is examined in light of thermal stability of CoPtCr-SiO2 media. The K-u of Co-10 at % Cr shows a high value of similar to 5 x 10(6) erg/cm(3), which is much higher than that reported by Bolzoni et aL The addition of Pt to the Co-10 at % Cr film results in a further enhancement of K-u. A maximum K-u of nearly 10 x 10(6) erg/cm(3) is observed at 25 similar to 30 at % Pt. All series of films with various Cr contents show maximum values of K. at 25 similar to 30 at % Pt. The maximum value for CoPt (Cr = 0) films reaches similar to 15 X 106 erg/cm(3). The value of magnetocrystalline anisotropy of grains K-u(g) calculated by taking account of the volume fraction of CoPtCr grains, decreases as the SiO2 content increases. However, the K-u(g) maintains a large value of more than 7 x10(6) erg/cm(3), even at 10 at % SiO2 in addition to (Co90Cr10)(80)Pt-20, which indicates a high potential of CoPtCr-SiO2 media to resist thermal agitation of magnetization.
CoCrPt-SiO2/Ru 垂直磁気記録媒体における磁気特性のPt，Cr組成依存性査読有り

及川忠昭, 島津武仁, 稲葉祐樹, 佐藤英夫, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　28　(3)　254-257　2004年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.28.254 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500667</BIBID></RIEC>
シリンダ状媒体用ヘッドスライダの設計と再生分解能評価査読有り

山田洋, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会誌　28　(4)　561-564　2004年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.28.561 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500861</BIBID></RIEC>
1-1 高速転送シリンダ状磁気ストレージの記録再生特性(第1部門マルチメディアストレージ)

山田洋, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

映像情報メディア学会年次大会講演予稿集　2004　_1-1-1_-_1-1-2_　2004年
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/iteac.2004.0__1-1-1_ 　

ISSN：1343-1846

詳細を見る詳細を閉じる

A cylindrical magnetic storage system aiming at realization of high transfer-rate and high areal-density was built as a trial. The system has the possibility of simplifying multiple-head control. Double-layered perpendicular medium was made on the cylindrical substrate and fundamental read/write characteristics using a single-pole-type writer and a GMR reader for cylindrical media were obtained.
Sharrock relation for perpendicular recording media with higher-order magnetic anisotropy terms 査読有り

O Kitakami, T Shimatsu, S Okamoto, Y Shimada, H Aoi

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS　43　(1A-B)　L115-L117　2004年1月
出版者・発行元：INST PURE APPLIED PHYSICS
DOI： 10.1143/JJAP.43.L115 　

ISSN：0021-4922

詳細を見る詳細を閉じる

Based on the Stoner-Wohlfarth model, we have studied the effects of higher order magnetic anisotropy terms on the dynamic coercivity of perpendicular magnetic recording media. The waiting time,dependence of the dynamic coercivity H-c becomes very gradual due to the presence of the second-order anisotropy constant, reflecting the fact that the higher-order anisotropy appreciably enhances the energy barrier for thermal stability. It is found that the behavior of H-c can be perfectly described by modifying the well-known Sharrock formula as H-c = H-K {1 - [(k(B)T/K*V)ln(f(0)t'/ln 2)](n)} and the higher-order anisotropy term appreciably enhances both the effective anisotropy constant K* and the index n.
Preliminary investigation for a cylindrical magnetic storage system 査読有り

H Yamada, T Shimatsu, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　39　(6)　3619-3621　2003年11月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2003.815433 　

ISSN：0018-9464

詳細を見る詳細を閉じる

A cylindrical magnetic storage system was built and preliminary measurements were made. The system is expected to overcome the writing problems at high areal densities caused a by write head skew angle and is aimed at the realization of 1-Tb/in(2) 2-Gb/s perpendicular magnetic recording. Cylindrical substrates, sputtering equipment, and a read/write tester for a cylindrical magnetic storage were fabricated. For this preliminary investigation, the length and diameter of the cylindrical substrates were 1 in. Thin films (protective layer, storage layer, seed layer, etc.) were deposited by rotating the cylindrical substrate during the sputtering process. Fundamental read/write characteristics were measured using an 8-mm video-tape-recorder metal-in-gap head and a merged giant magnetoresistive head with a pico-slider.
Development of ultra-high density perpendicular recording media [Invited] 査読有り

T. Shimatsu, O. Kitakami

Digests of International Symposium on Ultra-High Density Spinic Storage Systems　(TA-07)　22-27　2003年10月30日
Large perpendicular magnetic anisotropy of CoPtCr/Ru films for granular-type perpendicular media 査読有り

T. Shimatsu, H. Sato, T. Oikawa, Y. Inaba, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

Digests of International Symposium on Ultra-High Density Spinic Storage Systems　(PS-19)　68-69　2003年10月30日
Formation of magnetic cluster and remanence coercivity in granular-type perpendicular media 査読有り

T Shimatsu, T Oikawa, Y Inaba, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　39　(5)　2335-2337　2003年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2003.816289 　

ISSN：0018-9464

eISSN：1941-0069

詳細を見る詳細を閉じる

The magnetic cluster size D-cluster of perpendicular recording media, which is a main factor in media noise, is discussed in terms of demagnetizing field of magnetic clusters, remanence coercivity, and magnetization switching. It was shown that the values of remanence coercivity obtained by subtracting thermal agitation effect H-0 are similar to70% of those calculated using the Stoner-Wohlfarth model taking account of the c-axis distribution, H-r(S-W), even in CoPtCr-SiO2 media with well segregated grains. Demagnetizing field of magnetic cluster H-d is calculated as a function of the ratio of Dcluster to film thickness, delta. An intrinsic remaneme coercivity H-0(int) was obtained by compensating the Ho value by the H-d(H-0(int) = H-0 + H-d). The H-0(int) values are very close to those of H-r(S-W), especially in media with well-segregated grains. This result means that the magnetization reversal of these media is mainly determined by coherent rotation of magnetization; however, the demagnetizing field of magnetic cluster, besides thermal agitation effect, reduces the value of H-0.
CoPtCr-SiO2グラニュラー垂直磁気記録媒体招待有り査読有り

竹野入俊司, 酒井泰志, 榎本一雄, 及川忠昭, 渡辺貞幸, 上住洋之, 島津武仁, 村岡裕明, 中村慶久

日本応用磁気学会誌　27　(4)　940-945　2003年9月

詳細を見る詳細を閉じる

トピックス <RIEC><DUMMY>あ</DUMMY><BIBID>2003500404</BIBID></RIEC>
Effect of lattice strain on soft magnetic properties in FeCo/NiFe(Cr) thin films with 2.4 T 査読有り

T Shimatsu, H Katada, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　39　(5)　2365-2367　2003年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2003.815451 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The soft magnetic property of FeCo films with thin NiFe or NiFeCr seed layers (saturation flux density of 2.4 T) is discussed in relation to lattice strain of the FeCo films. The coercivity along hard axis of magnetization (H-c(HA)) reduces as the Ar pressure during sputtering deposition decreases, and moreover, shows the lowest value at FeCo thickness of 50-100 nm. FeCo films show bcc-(110) preferred grain orientation with the <110> direction sharply perpendicular to the film plane. X-ray diffraction (XRD) patterns indicate that the absolute magnitude of the lattice strains of (110), (-110), and (001) planes reduce as the Ar pressure decreases. Magnetic anisotropy energy in (110) plane (E) was calculated by including magnetostrictive energy due to the lattice strain. It was successfully shown that the Ar pressure dependence of E is in good agreement with that of H-c(HA) Moreover, it is suggested that thickness dependence of H-c(HA) is significantly related to that of magnetostrictive energy. It is likely that less lattice deformation, which is formed by the hetero-epitaxial growth of the FeCo(110) plane on the fcc-(111) plane of the NiFe(Cr) layer, is a key to derive soft magnetic properties in the FeCo/NiFe(Cr) films.
Magnetic cluster size and activation volume in perpendicular recording media 査読有り

T Shimatsu, H Uwazumi, T Oikawa, Y Inaba, H Muraoka, Y Nakamura

JOURNAL OF APPLIED PHYSICS　93　(10)　7732-7734　2003年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1557967 　

ISSN：0021-8979

詳細を見る詳細を閉じる

The magnetic cluster size D-cluster of perpendicular recording media, which is a main factor in media noise, is discussed in terms of activation volume, intergranular exchange coupling, and the slope of magnetization curves. It was experimentally shown that the values of D-cluster (observed by magnetic force microscopy in the ac demagnetized state) are similar to55 nm for CoPtCr-SiO2 media of 24 nm thickness, and are several times larger than activation diameter D-act (D-act=V-act/delta, V-act; the activation volume). D-cluster decreases as the film thickness delta decreases, particularly in a series of media with small intergranular exchange coupling, while D-act is nearly constant at similar to10 nm. It was experimentally shown that the slope of the magnetization curve alpha decreases as the value of D-cluster/delta decreases, and reaches a value of approximately 1 at D-cluster/delta of around 2. The results suggest that reduction of film thickness delta is important in order to realize both small D-cluster and large alpha values in granular-type perpendicular recording media. (C) 2003 American Institute of Physics.
CoPtCr-SiO2を用いた垂直磁気記録媒体の磁気特性と記録再生特性査読有り

及川忠昭, 上住洋之, 島津武仁, 村岡裕明, 中村慶久

日本応用磁気学会誌　27　(4)　196-199　2003年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.27.196 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500403</BIBID></RIEC>
シリンダ状媒体を用いた磁気ストレージ装置の基礎検討査読有り

山田洋, 島津武仁, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　27　(4)　265-268　2003年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.27.265 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500387</BIBID></RIEC>
Co/Pt人工格子垂直磁気記録媒体へのB添加効果とNiAlシード層効果査読有り

島津武仁, 猪狩孝洋, 寺川潤, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　27　(4)　210-214　2003年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.27.210 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500381</BIBID></RIEC>
反強磁性的な磁化結合による垂直磁気記録媒体裏打層の単磁区化査読有り

島津武仁, 本間一人, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　27　(4)　230-233　2003年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.27.230 　

ISSN：0285-0192

詳細を見る詳細を閉じる

<RIEC><DUMMY>あ</DUMMY><BIBID>2003500383</BIBID></RIEC>
Magnetic cluster size and magnetization curves in perpendicular recording media 査読有り

T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura

Joint NAPMRC 2003 - Digest of Technical Papers [Perpendicular Magnetic Recording Conference]　35　2003年
出版者・発行元：Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/NAPMRC.2003.1177039 　

詳細を見る詳細を閉じる

Summary form only given. Magnetic cluster size of perpendicular recording media, which is a dominant factor for media noise was discussed relating to activation volume, the slope of magnetization curves, and remanence coercivity.
Magnetization reversal and activation volume of perpendicular recording media 査読有り

T Shimatsu, H Uwazumi, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　38　(5)　1973-1975　2002年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2002.801790 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Magnetization reversal and thermal agitation of magnetization are quantitatively evaluated using a pulse magnetometer for several kinds of perpendicular magnetic recording media. In media with well-segregated grains, magnetization reversal is confirmed to proceed by coherent switching of magnetization, however, intergranular exchange coupling reduces the remanence coercivity, especially in superlattice media and amorphous/granular composite media. The activation volume in CoCr-based alloy media is experimentally indicated to be nearly the same as that of physical grain volume. It is successfully shown that media noise has a clear relation to both activation diameter and the strength of intergranular exchange coupling. It is likely that the values of activation diameter and the strength of intergranular exchange coupling are main factors to determine the cluster size of magnetization, and they must be reduced to improve the media noise performance.
Microstructure and magnetic properties of CoPtCr-SiO2 perpendicular recording media 査読有り

T Oikawa, M Nakamura, H Uwazumi, T Shimatsu, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　38　(5)　1976-1978　2002年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2002.801791 　

ISSN：0018-9464

詳細を見る詳細を閉じる

SiO2 added CoPtCr magnetic layer is employed for the perpendicular recording media. The microstructure, magnetic properties, and recording performance of these media are discussed. Very fine grains of the size of similar to7 rim, surrounded by amorphous-like grain boundaries, are realized together with good c-axis orientation normal to the film plane. It is considered that the addition Of SiO2 to CoPtCr is very effective to realize well-isolated fine-grain structure without disturbing the epitaxial growth of CoPtCr grains on Ru underlayer. The medium with 12-nm-thick recording layer shows a large perpendicular anisotropy K-u of similar to4 x 10(6) erg/cm(3), and high coercivity H-c of similar to4 kOe. Moreover, the medium shows excellent SNR performance together with high thermal stability, indicating a great potential for high-density perpendicular recording media.
Thermal agitation of magnetization and recording performance of Co(B)-Pd superlattice perpendicular recording media 査読有り

T Shimatsu, M Terakawa, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　38　(5)　2048-2050　2002年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2002.801830 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Magnetic properties and recording performance are discussed for Co-Pd(1 nm)](9) and [(Co-27 at% B)/Pd(1 nm)](9) superlattice perpendicular recording media as a function of the Co or Co-B layer thickness delta(Co) or delta(CoB). The Co-Pd media shows large values of perpendicular anisotropy K-u of 5.7 x 10(6) erg/cm(3) (delta(Co) =similar to 0.25 nm) and KuVact/kT of more than 200 (delta(Co) > 0.3 nm), indicating a high potential to resist thermal instability (V-act; the activation volume k; the Boltzmann constant T; the absolute temperature). However, the thickness dependence of KuVact/kT was not simply coincident with that of K-u. Magnetic characterization reveals that intergranluar exchange coupling decreases as the delta(Co) or delta(CoB) decreases, leading to higher signal-to-medium-noise ratio SNmR. The addition of B to Co layer reduces the values of K-u and KuVact/kT significantly, however, and is effective to reduce intergranluar exchange coupling and activation volume, resulting in higher SNmR.
Soft magnetic properties and microstructure of NiFe(Cr)/FeCo/NiFe(Cr) films with large saturation magnetization 査読有り

H Katada, T Shimatsu, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　38　(5)　2225-2227　2002年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2002.802668 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The soft magnetic properties of FeCo films, sandwiched by thin NiFe or NiFeCr films, are discussed in relation to the microstructure. Ta/NiFe(Cr)(5 nm)/FeCo(100 nm)/NiFe(Cr)(5 nm)/Ta films prepared using the URV sputtering process with pure Ar plasma show bcc(110) preferred grain orientation of FeCo layer with the <110> direction sharply perpendicular to the film plane, resulting in soft magnetic properties. No significant difference in soft magnetic properties was observed by the use of nonmagnetic NiFeCr layers instead the NiFe layers, moreover, by varying FeCo composition between 25 and 30 at%Co. The best thickness of the FeCo layer in order to realize soft magnetic properties was found to be similar to100 nm in the present study, with a high saturation magnetization of 2.3 T. An addition of N-2 gas to Ar plasma during film deposition did not lead to an improvement of the soft magnetic properties. A film of [FeCo(100 nm)/NiFe(5 nm)]4 layer structure was subjected to the fabrication of single-pole-type recording head, and it is successfully demonstrated that the film has a sufficient softness to be used for the recording head application.
High mobility of surface atoms and induced anisotropy in very thin permalloy films 査読有り

H Katada, T Shimatsu, H Watanabe, Watanabe, I, H Muraoka, Y Nakamura, Y Sugita

IEEE TRANSACTIONS ON MAGNETICS　38　(5)　2664-2666　2002年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/TMAG.2002.801974 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The induced uniaxial anisotropy field H-k in very thin Ni79Fe21 films, sandwiched by seed and protective Ta layers, was investigated. Films prepared by an ultra-high vacuum sputtering process show a very sharp fiber texture of fcc-<111> perpendicular to the film plane, even with a thin film of 3 nm. The H-k value was found to decrease as the film thickness decreased below 20 nm, even after an annealing procedure in a magnetic field. The change in the induced anisotropy energy K-u was measured as a function of the temperature while applying a dc magnetic field parallel to the hard axis of magnetization. The value of K-u of as-deposited thin films decreases significantly with increasing temperature from 50 degreesC to 100 degreesC and the K-u reduction in a film of 5 nm reaches similar to 40%. It is likely that this K-u reduction is mainly caused by realignment of atom pairs at film surfaces along the field direction. This is supported by the low activation energy of the K-u reduction process. It is successfully shown that the high mobility of surface atoms should disrupt the alignment of atom-pairs parallel to the field direction during the film deposition and annealing process, resulting in the formation of magnetically isotropic layers at surfaces. The thickness of this isotropic layer was estimated to be similar to 0.8 nm and the isotropic surface-layer is likely to reduce the H-k value of very thin films.
垂直磁気記録媒体の低ノイズ化と磁化の熱擾乱

島津武仁, 上住洋之, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　102　(186)　7-12　2002年6月28日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2002-15
極薄パーマロイ薄膜の誘導磁気異方性とその温度依存性査読有り

片田裕之, 島津武仁, 渡辺博志, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会誌　26　(5)　752-755　2002年5月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.26.752 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The induced uniaxial anisotropy field Hk in very thin Ni79Fe21 films, sandwiched by seed and protective Ta layers, was investigated. Films prepared by using a UHV sputtering process show a very sharp fiber texture of fcc-<111> even with a film thickness of 3 nm. The Hk value was found to decrease as the film thickness decreases below 20 nm, even after an annealing procedure in a magnetic field. The change in the induced anisotropy energy Ku was measured as a function of the temperature while applying a dc magnetic field parallel to the hard axis of magnetization. The value of Ku of as-deposited thin films decreases significantly with increasing temperature from 50°C to 100°C. The Ku reduction in a film of 5 nm reaches ∼40% of that of the original value. It is likely that the Ku reduction at temperatures below 100°C is mainly caused by alignment of atom pairs at film surfaces. The thickness of film surfaces with highly mobile atoms was estimated to be 5-6 A. The high mobility of surface atoms may disrupt the alignment of atom-pairs parallel to the field direction during the film deposition and annealing process, resulting in the smaller Hk of very thin films.
Recording performance and magnetization switching of CoTb/CoCrPt composite perpendicular media 査読有り

H Uwazumi, T Shimatsu, Y Sakai, K Enomoto, S Takenoiri, S Watanabe, H Muraoka, Y Nakamura

JOURNAL OF APPLIED PHYSICS　91　(10)　8058-8060　2002年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1452273 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Magnetic properties, recording performance, and thermal stability of CoTb amorphous/CoCrPt granular composite media are discussed. Thermal stability at low recording density of the composite media with CoCrPtB improves significantly as CoTb thickness increases, in accord with the increase of loop squareness, M-r/M-s. The media having CoTb thickness of more than 6 nm show almost no signal decay. Moreover, the signal-to-medium-noise ratio, SNR, improves with increasing CoTb thickness up to 6 nm. CoTb(6 nm)/CoCrPtB(20 nm) medium shows the best SNR performance under the present experimental conditions with no thermal decay. Media noise of the composite media with CoCrPt increases super linearly from similar to300 kfci, which is caused by the percolation of the recorded bits, probably due to the strong exchange coupling in the CoTb layer. The media with CoCrPtB shows less media noise than that with CoCrPt, and the super-linear increase of this media noise starts at similar to400 kfci which is higher than that of the media with CoCrPt. It is thought that the well-segregated grain structure of CoCrPtB layer, having the enhanced and fine distribution of M-s, reduces the magnetic cluster size effectively, resulting in the reduction of the media noise. (C) 2002 American Institute of Physics.
High thermal stability in CoPrTb/CoCrTa composite perpendicular media 査読有り

T Shimatsu, H Muraoka, Y Nakamura, Y Sonobe, Y Satodate, K Muramatsu, Watanabe, I

JOURNAL OF APPLIED PHYSICS　91　(10)　8061-8063　2002年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1452274 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Thermal stability and media noise performance of the CoPrTb/CoCrTa composite perpendicular media are discussed. Angular dependence of remanance coercivity and the DeltaM plot indicate that magnetization reversal in the CoPrTb/CoCrTa composite media is mainly proceeded by local switching of magnetization, while the magnetization loop of the composite media show very steep slope and large squareness M-r/M-s compared to those of CoCrTa media. Recording performance of (CoPrTb/CoCrTa)/Ti/CoZrNb double-layered perpendicular media was examined using a single-pole-type write head and a GMR read head. The recording resolution, D-50, of a CoPrTb(10 nm)/CoCrTa(20 nm) composite medium is about 50 kfrpi higher than that of CoCrTa medium, and the signal to medium noise ratio, S/N-m, was about 10 dB higher than that of the CoCrTa medium (at 300 kfrpi). The CoPrTb/CoCrTa composite media show very high thermal stability of read back signals even at low recording density, although the value of M-r/M-s is smaller than 0.9. The continuous CoPrTb layer is assumed to prevent the thermal reversal of individual grains of the CoCrTa layer by the interfacial exchange coupling. (C) 2002 American Institute of Physics.
Switching field distribution of 40 Gbit/in.(2) longitudinal media obtained by subtracting thermal agitation of magnetization 査読有り

H Uwazumi, T Shimatsu, Y Kuboki

JOURNAL OF APPLIED PHYSICS　91　(10)　7095-7097　2002年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.1456393 　

ISSN：0021-8979

詳細を見る詳細を閉じる

Switching field distributions (SFDs), are presented for longitudinal media of similar to40 Gbit/in.(2) and the influence of thermal agitation of magnetization is discussed. Two remanence curves were measured at different sweep rates of applied field of similar to10 and similar to10(8) Oe/s, respectively, and SFD curves were obtained by differentiating the remanence curves. The SFD becomes significantly narrower at the higher field sweep rate. A SFD curve without the effect of thermal agitation was calculated using Sharrock's equation. The full width at half maximum of the SFD curve at 10 Oe/s, DeltaH(r)/H-r, is 0.45 for an isotropic medium, while that estimated without the thermal agitation effect DeltaH(0)/H-0 is 0.24, indicating that the SFD at the recording frequency is nearly half that measured at vibrating sample magnetometer (VSM) time scales. The DeltaH(0)/H-0 of the similar to40 Gbit/in.(2) medium is much smaller than that of a 15 Gbit/in.(2) medium used for comparison, although the DeltaH(r)/H-r is similar to1.4 times larger than that of the 15 Gbit/in.(2) medium due to thermal agitation. The value of DeltaH(0)/H-0 is not influenced by the uniaxial anisotropy induced by substrate texture K-u(TX). This result indicates that the K-u(TX) is not effective for reducing SFD at recording frequencies, although the K-u(TX) strongly affects the SFD at VSM times scales. The improvement of recording performance with increasing K-u(TX) may be related to suppression of thermal relaxation of the remanent magnetization at bit transitions, immediately after the writing process. (C) 2002 American Institute of Physics.
A Simple Analysis for Magnetic Behaviors of Exchange-Coupled Granular/Continuous Perpendicular Magnetic Recording Media 査読有り

Osamu Kitakami, Takehito Shimatsu, Hiroaki Muraoka

Japanese Journal of Applied Physics　41　(4B)　L455-L457　2002年4月15日
出版者・発行元：公益社団法人応用物理学会
DOI： 10.1143/JJAP.41.L455 　

ISSN：0021-4922

詳細を見る詳細を閉じる

Volume 41 (2002) No. 4B (Apr 15)
CoCrPt-(Ta,B)垂直磁気記録媒体の初期成長層の低減と磁気特性査読有り

上住洋之, 島津武仁, 寺川潤, 酒井泰志, 竹野入俊司, 渡辺貞幸, 村岡裕明, 中村慶久

日本応用磁気学会誌　26　(4)　205-209　2002年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.26.205 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Reduction of the thickness of the initial film-growth layer of CoCrPt-based perpendicular recording media was investigated using TiCr, CoCr, and Ru seed layers. Magnetic analysis revealed that the initial layer has small perpendicular magnetic anisotropy Ku, and that the thickness of the initial layer was about 10-15 nm with a TiCr seed layer, and 1-6 nm with a CoCr or a Ru seed layer. X-ray diffraction patterns and TEM images indicated that the initial layer contains an fcc-like structure, and that many stacking faults exist in CoCrPt-based perpendicular films, even with a CoCr or a Ru seed layer, The improvement in epitaxial film growth obtained by using a CoCr or a Ru seed layer is very effective in reducing the thickness of the initial layer, while is found to prevent the segregation of Cr from Co, resulting in larger intergranular exchange coupling.
Co(-B)/Pd人工格子垂直磁気記録媒体の磁気異方性と磁化の熱擾乱査読有り

島津武仁, 寺川潤, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　26　(4)　219-223　2002年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.26.219 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Magnetic properties and recording performance are discussed for [Co/Pd (1 nm)]9 and [(Co-27 at% B)/Pd (1 nm)]9 superlattice perpendicular recording media as a function of the Co or Co-B layer thickness, δCo or δCoB. The perpendicular magnetic anisotropy Ku of these media shows maximum values of 5.7 x 106 erg/cm3 (Co/Pd) and 3.2 x 106 erg/cm3 (Co-B/Pd) at δCo or δCoB of around 0.2-0.3 nm. The KuV/kT (V; the activation volume, k; the Boltmann constant, T; the absolute temperature) of the Co/Pd medium has large values of more than 200 (δCo>0.3nm), while the KuV/kT in both media significantly decreases as the thickness decreases, which is not coincident with the thickness dependence of Ku. The value of Ku/2πMs2 (Ms; the saturation magnetization) in both media increase monotonically as the thickness decrease, and is ∼10 at δCo or δCoB of around 0.2-0.3 nm. The signal-to-medium-noise ratio SNmR of the Co-B/Pd media is higher than that of the Co/Pd media, and increase as δCoB decrease. TEM images and magnetic characterization revealed that these differences in SNmR are mainly due to the difference in the strength of intergranular exchange coupling.
Co-PrTb/Co-Cr-Ta複合型垂直磁気記録媒体の熱安定性と記録再生特性査読有り

島津武仁, 村岡裕明, 里舘慶久, 渡辺功, 中村慶久

日本応用磁気学会誌　26　(4)　229-232　2002年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.26.229 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The thermal stability and medium noise performance of Co100-X(PrTb)X/Co-Cr-Ta (X = 21-31.7 at%) composite perpendicular media are discussed. The perpendicular magnetic anisotropy Ku shows a maximum at X = ∼25, although the saturation magnetization decreases gradually as X increases. The ratio of "intrinsic" remanence coercivity obtained by subtracting the termal agitation to the anisotropy field, H0/Hk, increases as X increases, indicating a reduction of the exchange coupling of magnetization. The medium noise of the composite media, which have CoZrNb soft back-layers, decreases gradually as X increases and as the Co-PrTb thickness decreases, resulting in a higher signal-to-medium-noise ratio SNmR. The SNmR fo a Co76.5(PrTb)23.5 (5 nm) / Co77Cr19Ta4 (25 nm) composite medium is about 8 dB higher than that of a Co77Cr19Ta4 (30 nm) medium at 300 kFRPI. The composite media show high thermal stability of read-back signals even at low recording density. However, the thermal signal-decay increases gradually as the Co-PrTb thickness decreases, and also as X increases, indicating that the thermal stability has a trade-off relation with the medium noise performance.
NiFe/FeCo/NiFe 高飽和磁化薄膜の構造と軟磁気特性査読有り

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　26　(4)　505-508　2002年4月

DOI： 10.3379/jmsjmag.26.505 　
UHVスパッタにより作製したFeCo薄膜の軟磁性と単磁極ヘッドへの応用

片田裕之, 島津武仁, 高橋正晴, 渡辺功, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　101　(564)　17-24　2002年1月10日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.26.1.0_17 　

ISSN：1342-6893

詳細を見る詳細を閉じる

MR2001-91
Magnetization reversal of perpendicualr recording media characterized using a pulse magnetometer 査読有り

T. Shimatsu, H. Uwazumi, H. Muraoka, Y. Nakamura

INTERMAG Europe 2002 - IEEE International Magnetics Conference　2002年
出版者・発行元：Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/INTMAG.2002.1001310 　

詳細を見る詳細を閉じる

Magnetization reversal of various kinds of perpendicular recording media was characterized using a pulse magnetometer (T. Shimatsu et al, Digests of PMRC 2000, p. 141, 2000), and discussed relating to media noise performance. Co(B)/Pd superlattice media, CoTb(Pr)/CoCr(Ta,Pt) composite media (T. Shimatsu et al, Digests of MMM Conf., FB-06, 2001 H. Uwazumi, ibid., FB-05, 2001) and CoCr(Ta, Pt, B) media were subjected to the study.
Co(B)/Pd人工格子垂直磁気記録媒体の磁気異方性と磁化の熱擾乱

島津武仁, 寺川潤, 渡辺功, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　101　(335)　9-14　2001年10月4日

詳細を見る詳細を閉じる

MR2001-27
Thermal stability in perpendicular recording media 招待有り査読有り

T Shimatsu, H Uwazumi, H Muraoka, Y Nakamura

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　235　(1-3)　273-280　2001年10月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/S0304-8853(01)00358-4 　

ISSN：0304-8853

詳細を見る詳細を閉じる

Magnetic and structural properties of CoCrPt based perpendicular recording media required to achieve both high thermal stability and low-noise performance are discussed, based on experimental results obtained using a pulse magnetometer. Experimental and theoretical analysis reveal that for CoCrPt based media of 20 nm thickness having the thermal stability factor KuV/(kT)approximate to 80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H-r/H-k is similar to0.35. Furthermore, in order to realize a large squareness M-r/M-x of nearly 1.0, which is required to resist the thermal agitation effect at low recording density, we find that the value of perpendicular magnetocrystalline anisotropy. K-u needed to be more than three times larger than 2 piM(s)(2). X-ray diffraction patterns suggested that the suppression of structural imperfections in the HCP structure, particularly in the initial growth layer, is the key issue to induce larger K-u value in the CoCrPt based media. (C) 2001 Elsevier Science B.V. All rights reserved.
Thermal agitation of magnetization in CoCrPt perpendicular recording media 査読有り

T Shimatsu, H Uwazumi, Y Sakai, A Otsuki, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　37　(4)　1567-1569　2001年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.950902 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Magnetic and structural properties of CoCrPt based perpendicular recording media required to achieve both high thermal stability and low-noise performance are discussed, based on experimental results obtained using a pulse magnetometer. Experimental and theoretical analysis reveal that for CoCrPt based media of 20 nm thickness having the thermal stability factor KuV/(kT) approximate to 80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H-r/H-k, is similar to0.35. Furthermore, if the strictest condition of demagnetizing factor, 4 pi, for perpendicular media is assumed, in order to realize a large squareness MrMs of nearly 1.0, which is required to resist the thermal agitation effect, we find that the value of perpendicular magnetocrystalline anisotropy, K-u, has to be more than 3 times larger than 2 piM(s)(2).
Recording performance of CoCrPt-(Ta, B)/TiCr perpendicular recording media 査読有り

H Uwazumi, T Shimatsu, Y Sakai, A Otsuki, Watanabe, I, H Muraoka, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　37　(4)　1595-1598　2001年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.950911 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The magnetic properties, microstructure and the recording performances of CoCrPt-(Ta, B)/TiCr perpendicular magnetic recording media were studied in conjunction with the effect of thermal agitation. The addition of Th or B to CoCrPt media significantly improves its low noise performance, mainly due to the reduction of grain size and intergranular magnetic interactions. However, adding Ta or B also reduces the value of perpendicular magnetic anisotropy, K-u, especially in the initial growth layer, resulting in the degradation of thermal stability. In order to achieve high thermal stability without degrading the low noise performance of these media, an M-r/M-s value of nearly 1.0 is required. This may be achieved by suppressing of the reduction of K-u and the reducing intergranular magnetic interactions, whilst maintaining their small grain size.
Induced uniaxial magnetic anisotropy and film magneto striction in very thin permalloy films 査読有り

H Katada, T Shimatsu, Watanabe, I, H Muraoka, Y Nakamura, Y Sugita

IEEE TRANSACTIONS ON MAGNETICS　37　(4)　2334-2336　2001年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.951164 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The induced uniaxial anisotropy field H-k in very thin films sandwiched by Ta or Cu layers was investigated. The value of H-k of the Ta/Cu/Ni79Fe21/Cu/Ta film decreases as film thickness decreases below 20 mu, even after an annealing procedure in a magnetic field. This H-k reduction is similar to that of the Ta/Ni79Fe21/Ta films, indicating that the H-k reduction is independent of surface energy and/or crystal structure of seed layers. The value of film magnetostriction lambda (p-p) of the Ta/NiFe/Ta films gradually increases as the thickness decreases, which is coincident with the reduction of H-k. However, the increase of the lambda (p-p) values, by decreasing Ni concentration or annealing the films, resulted in conflicting H-k values. These results indicate that the H-k reduction in thin films is not simply caused by the magnetostrictive effect.
CoPrTb/CoCrTa垂直複合膜媒体の熱安定性と記録再生特性

島津武仁, 村岡裕明, 里舘慶洋, 村松孝一, 渡辺功, 中村慶久

電子情報通信学会技術研究報告 MR　101　(106)　19-24　2001年6月1日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.25.37.0_19 　

ISSN：1342-6893

詳細を見る詳細を閉じる

MR2001-12
CoCrPt系垂直媒体の初期成長層の低減と垂直磁気異方性

上住洋之, 島津武仁, 寺川潤, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告 MR　101　(105)　21-26　2001年5月31日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

MR2001-4
CoCr系垂直磁気記録媒体の磁化の熱擾乱と磁気特性査読有り

島津武仁, 上住洋之, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会誌　25　(41366)　539-542　2001年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.25.539 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The effect of thermal agitation of magnetization on the magnetic properties of CoCr-based perpendicular recording media was studied using a pulse magnetometer. In media having well-segregated grains, we found that the angular dependence of the "intrinsic" remanence coercivity H0, obtained by subtracting the thermal agitation of magnetization, was nearly the same as that of coherent switching of magnetization calculated by taking account of the angular distribution of the preferred axis. Experimental and theoretical analyses suggested that the achievable maximum value of the ratio of H0 to the anisotropy field Hk is 0.7 to 0.8 at 20-nm thickness. Results show that the value of perpendicular anisotropy Ku must be more than 3 times larger than 2πMs2 values in order to achieve an Mr/Ms of nearly 1.0 resisting the thermal agitation effect in CoCr-based perpendicular media.
極薄軟磁性薄膜の誘導一軸磁気異方性査読有り

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会誌　25　(41366)　867-870　2001年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.25.867 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The induced uniaxial anisotropy field Hk in very thin permalloy films, sandwiched by seed and protective Ta and Cu layers, was investigated. The value of Hk of the Ta/Cu/ Ni79Fe21/Cu/Ta films was found to decrease as the film thickness decreases below 20 nm, even after an annealing procedure in a magnetic field. This Hk reduction is similar to that of Ta/Ni79Fe21/Ta films, indicating that the Hk reduction is independent of the surface energy or crystal structure of the seed and protective layers. Thickness dependence of film magnetostriction λp-p of these films did not show any clear correlation with that of Hk, indicating that the Hk reduction is not simply caused by the magnetostrictive effect at thin films. The higher mobility of surface atoms may disrupt the alignment of atom-pairs parallel to the field direction during film deposition and annealing, resulting in the smaller induced anisotropy of very thin films.
垂直磁気記録媒体の磁気的微細構造と熱緩和

島津武仁, 村岡裕明, 中村慶久

日本応用磁気学会第118回研究会資料　57-62　2001年2月

詳細を見る詳細を閉じる

118-11
極薄軟磁性薄膜の誘導磁気異方性と薄膜磁歪

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

電子情報通信学会技術研究報告 MR　100　(564)　1-6　2001年1月12日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.25.2.0_1 　

ISSN：1342-6893

詳細を見る詳細を閉じる

MR2000-100
Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media 査読有り

T Shimatsu, SJ Greaves, K Muramatsu, Watanabe, I, H Muraoka, Y Sugita, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　36　(5)　2375-2377　2000年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.908435 　

ISSN：0018-9464

詳細を見る詳細を閉じる

We measured the value of rotational hysteresis loss W-r for various CoCrTa perpendicular media, and discussed the dependence of W-r and the hysteresis integral R-h On the perpendicular anisotropy and the strength of intergranular exchange coupling. Simulated results using a model based on the Landau-Lifshitz-Gilbert equation were compared with the experimental results. The experimental and theoretical studies revealed that improvement of the c-axis alignment significantly reduces W-r, resulting in a small R-h value of similar to 0,2, increase of intergranular exchange coupling shifts the applied field at which W-r reaches a maximum, H-p, to a lower field and produces a large R-h. Decrease of K-u also shifts H-p to a lower field but is accompanied by a reduction of R-h. These results imply that the values of R-h and H-p are strongly related to the structural and magnetic properties, and analysis of rotational hysteresis loss appears to be a useful technique to characterize perpendicular media.
Induced uniaxial magnetic anisotropy field in very thin NiFe and CoZrNb films 査読有り

H Katada, T Shimatsu, Watanabe, I, H Muraoka, Y Sugita, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　36　(5)　2905-2908　2000年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.908623 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The induced uniaxial anisotropy field in thin permalloy and CoZrNb films was investigated. The value of the induced anisotropy field H-k of permalloy films of 77-81 at%Ni concentration was found to decrease as the film thickness decreased below 20 nm, even after annealing procedure in a magnetic field. The value of H-k at 3 nm was found to be nearly half that at 20 nm, A series of CoZrNb amorphous films showed a qualitatively similar thickness dependence of H-k Moreover, a similar reduction of H-k was observed at 77 K, On the other hand, the easy axis of Ni79Fe21 films thinner than 20 nm was switched to the field direction by annealing with a magnetic field perpendicular to the easy axis of the as-deposited films, even at a low annealing temperature of 160 degrees C, The absolute value of H-k in the 3 nm film after annealing at 160 degrees C was nearly as Large as in the as-deposited film. It is likely that the rearrangement of atom pairs can easily occur in the surface region, resulting in the switching of the easy axis to the annealing field direction in very thin films.
グラニュラー系垂直磁気記録媒体の磁化の熱擾乱と磁気特性

島津武仁, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

電子情報通信学会技術研究報告 MR　100　(106)　7-12　2000年6月1日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.24.32.0_7 　

ISSN：1342-6893

詳細を見る詳細を閉じる

MR2000-2
数nm膜厚のNiFeおよびCoZrNb薄膜の誘導磁気異方性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

電子情報通信学会技術研究報告 MR　100　(106)　19-24　2000年6月1日
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/itetr.24.32.0_19 　

ISSN：1342-6893

詳細を見る詳細を閉じる

MR2000-4
Effect of a Ti seed layer on the magnetic properties of CoCrTa double-layered perpendicular media 査読有り

T Shimatsu, H Komagome, Watanabe, I, H Muraoka, Y Sugita, Y Nakamura

JOURNAL OF APPLIED PHYSICS　87　(9)　6367-6369　2000年5月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1063/1.372708 　

ISSN：0021-8979

詳細を見る詳細を閉じる

The effect of a Ti seed layer on the magnetic properties and microstructure of Co77Cr19Ta4 was studied in Co77Cr19Ta4/Ti/M (M=Co91Zr3Nb6, Fe, Co) double-layered perpendicular recording media. A thin Ti film of similar to 5 nm enhanced the c-axis alignment perpendicular to the film plane, resulting in a large perpendicular anisotropy K-u and the best magnetic properties under the present experimental conditions. The coercivity at this Ti thickness (3-3.7 kOe) was approximately half of the magnetocrystalline anisotropy field H-k estimated from the K-u value, even with the present thick 50 nm CoCrTa. The recording performance using a single-pole-type writing head showed that media with a 5 nm Ti layer had higher recording sensitivity compared to media without Ti layers, and a higher SN value at densities greater than 200 kFRPI. No significant loss of recording resolution due to the nonmagnetic Ti space between the CoCrTa and the back layers was observed by the use of the 5 nm Ti film. Moreover, the results for media with Fe back layers indicated that a thinner back layer with a high flux density can be used without any reduction of recording sensitivity and resolution. (C) 2000 American Institute of Physics. [S0021-8979(00)46208-0].
CoCrTa垂直磁気記録媒体の磁化の熱擾乱と磁気特性査読有り

島津武仁, 駒込博泰, 村松孝一, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

日本応用磁気学会誌　24　(2)　239-242　2000年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.24.239 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The effect of thermal agitation of magnetization on the magnetic properties of CoCrTa/Ti perpendicular media was studied by using a pulse magnetometer. The values of the "intrinsic" remanence coercivity H_o, obtained by subtracting the thermal agitation of magnetization, are several times larger than those of the remanence coercivity H_r measured experimentally at a field sweep rate of ～5 Oe/s. The value of H_o gradually approaches H_k as the CoCrTa thickness decreases, and shows values larger than 90% of H_k at thicknesses of less than 20 nm. This indicates the potential of perpendicular media to achieve H_r values equal to H_k. The activation volume gradually decreases as the thickness decreases, and is nearly the same as the mean grain volume at esthickness of less than 30 nm. This suggests that magnetization reversal within the grains is uniform at thicknesses of less than 30 nm, even though the grains have an elongated shape (30 nm x 9.5^2 nm^2 at 30 nm thickness, for instance). This will be another advantage of perpendicular media in resisting thermal agitation of magnetization.
CoCrTa/Ti/M(M:CoZrNb, Fe, Co)垂直二層膜媒体の磁気特性と記録再生特性査読有り

駒込博泰, 島津武仁, 吉田亮一, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

日本応用磁気学会誌　24　(2)　243-246　2000年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.24.243 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The Magnetic properties and recording performances of CoCrTa/Ti/M (M: CoZrNb, Fe, Co) double-layered perpendicular recording media were studied. It was revealed that a thin Ti film of 5 nm gave the most enhanced c-axis alignment perpendicular to the film plane in media with CoZrNb or Fe back-layers, resulting in the highest coercivity and squareness of CoCrTa. The recording performance of media with Fe back-layers, using a single-pole-type writing head, indicated that a thinner back-layer with a high flux density can be used without any reduction of the recording sensitivity and resolution, even though the Fe back-layers do not have good soft magnetic properties. However, hcp-Co back-layers degrade the recording sensitivity and resolution. The media noise of media with Fe or Co back-layers was significantly higher than that of CoZrNb back-layer media. It is suggested that these noise spectra are related to the domain structure of the back-layers.
数nm膜厚のパーマロイ薄膜の誘導磁気異方性査読有り

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会誌　24　(2)　539-542　2000年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.24.539 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The induced anisotropy in thin Ni79Fe21 films was investigated. The value of the induced anisotropy field Hk was found to decrease as the film thickness decreased, particularly below 20 nm, even after an adequate annealing procedure with a magnetic field. The value of Hk at 3 nm was found to be nearly half that at 200 nm. Almost the same thickness dependence of Hk was found to exist in both Ni77Fe23 and Ni81Fe19 films, except for slight differences in the absolute magnitude of Hk, depending on the composition. A series of CoZrNb amorphous films showed a qualitatively similar thickness dependence of Hk. On the other hand, the easy axis of the Ni79Fe21 films thinner than 20 nm was switched to the field direction by annealing with a magnetic field perpendicular to the easy axis of the as-deposited films, even at a low annealing temperature of 220°C. The absolute values of Hk in the 3 and 5 nm films after annealing were nearly as large as in the as-deposited films. It is likely that the rearrangement of atom pairs can easily occur in the surface region, resulting in the switching of the easy axis to the annealing field direction in very thin films.
Thermal fluctuation of magnetization in nanocrystalline FePt thin films with high coercivity 査読有り

T Shimatsu, JC Lodder, Y Sugita, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　35　(5)　2697-2699　1999年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.800956 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The effect of thermal fluctuations of magnetization on static and dynamic properties is discussed for nanocrystalline FePt films. The large magnetocrystalline anisotropy K-u of L1(0) type FePt results in large KuV/(kT) values of more than 70 even for very fine grain sizes of 7 similar to 8 nm, indicating the potential of this alloy film to resist thermal fluctuation of magnetization, It is successfully demonstrated that larger KuV/(kT) values of these films lead to lower magnetic viscosity. Annealing at higher temperature results in larger KuV/kT values and smaller V-act. The remanent coercivity measured at high sweep rate by using pulsed magnetic fields indicates the high thermal stability of these alloy films at high frequencies. However, the results indicated that care should be taken to induce an adequate magnitude of K-u for the FePt alloy to be used as ultrahigh density recording media.
Spin-valve transistor: Technologies and progress 招待有り査読有り

J. C. Lodder, D. J. Monsma, R. Vlutters, T. Shimatsu

Journal of Magnetism and Magnetic Materials　198　119-124　1999年6月1日
出版者・発行元：Elsevier Science Publishers B.V.
DOI： 10.1016/S0304-8853(98)01241-4 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The paper describes the necessary technologies needed for realizing a RT operating spin-valve transistor (SVT) which is in fact a magnetic controlled metal base transistor. The preparation of a 350×350 μm2 SVT consisting of an Si emitter and collector and Co/Cu/Co GMR multilayer are described. The metal bonding technology in vacuum is described, which is essential for preparing small SVTs with photolithography and etching technologies. The quality of the bonding interfaces as well as the interface between GMR layer and semiconductor are important for the electrical properties. In more general terms the SVT research also establishes the feasibility of various hybrid structures combining semiconductor technology and spin electronics.
CoCrTa/Ti/CoZrNb垂直二層膜媒体におけるTi層厚の低減と磁気特性査読有り

島津武仁, パウフィ・スリスティオ, 駒込博泰, 渡辺功, 杉田愃, 中村慶久

日本応用磁気学会誌　23　(2)　969-972　1999年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.23.969 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The effect of a Ti seed-layer on the magnetic properties and microstmctures of CoCrTa was studied in CoCrTa/Ti/CoZrNb double-layered perpendicular recording media. It was revealed that a thin Ti film of 5 nm, deposited at a substrate temperature of 230°C, gave the most enhanced c-axis alignment perpendicular to the film plane, showing the greatest perpendicular anisotropy. This large anisotropy yielded the best magnetic and recording properties under the present experimental conditions. The read-back amplitude at this Ti thickness was 3 times larger than that without the Ti layer, resulting in a higher ratio of signal to media noise. There was no significant loss in recording resolution due to the non-magnetic Ti space between the CoCrTa recording layer and the CoZrNb underlayer.
Metal bonding during sputter film deposition 査読有り

T Shimatsu, RH Mollema, D Monsma, EG Keim, JC Lodder

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS　16　(4)　2125-2131　1998年7月
出版者・発行元：AMER INST PHYSICS
DOI： 10.1116/1.581319 　

ISSN：0734-2101

詳細を見る詳細を閉じる

We studied the bonding between two flat Si substrates with thin metal films. The bonding was accomplished during thin film sputter deposition on contamination free surfaces of metal films. In this work we used Ti and Pt. Successful bonding of these metal films (each having a thickness of 10-20 nm) occurred at room temperature over the entire bonded area (12 mm x 12 mm). Self-diffusion, particularly at grain boundaries and film surface, was the mechanism for bonding. Suitable metal bonding only occurred if the film surface roughness is sufficiently smaller than the self-diffusion length of metals. Particularly in the bonding of Ti to Ti films, transmission electron microscope observation revealed that complete crystalline grains had been formed across the former interface between the single thin Ti films. The interfaceless bonding can be explained by recrystallization of the Ti lattice due to the high self-diffusion coefficient of Ti. This technique would be applied to bonding of wafers to fabricate thin film devices or microsystems. Moreover, this bonding technology can be used with many different thin film materials and various semiconductor substrates. (C) 1998 American Vacuum Society. [S0734-2101(98)05004-0].
High coercive force and low intergranular coupling in CoCrTa thin-film recording media fabricated under ultra clean sputtering process 査読有り

M. Imakawa, S. Ishibashi, M. Kuwabara, T. Shimatsu, M. Takahashi

Journal of Magnetism and Magnetic Materials　182　(3)　403-412　1998年3月4日
出版者・発行元：Elsevier
DOI： 10.1016/S0304-8853(97)01042-1 　

ISSN：0304-8853

詳細を見る詳細を閉じる

Ultra clean sputtering process (UC-process) was newly introduced in the fabrication of Co85.5Cr10.5Ta4 thin-film media to establish the control of microstructure of films. By applying the UC-process, the remarkable high-Hc value of about 2.8 kOe (15 nm/50 nm in CoCrTa/Cr thicknesses) was realized with no decrement in saturation magnetization. High-Hc of about 2 kOc (40 nm in magnetic layer thickness) remains even for extremely thin Cr thickness of about 5 nm. Magnetic torque analysis has revealed that magnetic anisotropy field of grains Hgrain k in the UC-processed media shows large values of about 6-7.5 kOc, which are about 20-50% larger than those of media fabricated under the normal sputtering process commonly used. The result of temperature dependence of saturation magnetization suggests that the appearance of large Hgrain k is mainly attributable to the decrease in Cr content in grains. On the other hand, the enhancement of the formation of homogeneously segregated grain boundary structure, which corresponds to the decrease of intergranular exchange coupling, was also found. The ultra clean sputtering process enables the control of the fine structure and induces the excellent features for magnetic properties even in commonly used CoCrTa material. © 1998 Elsevier Science B.V. All rights reserved.
Magnetic anisotropy and switching field of spindle-shaped metal particles for particulate recording media 査読有り

M Igaki, H Nagamori, T Shimatsu, M Takahashi

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　183　(1-2)　209-219　1998年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/S0304-8853(97)01109-8 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The difference of magnetic properties between spindle-and needle-shaped metal particles, which have almost the same thickness of about 17-27 nm, is discussed through a magnetic torque analysis for particulate films made of these metal particles. The effective magnetic anisotropy field of particles H-k(plc)(eff) are 6.3 and 6.5 kOe (averaged values), respectively, for spindle- and needle-shaped metal particles, showing no significant difference. Because of the interparticulate magnetostatic coupling, these H-k(plc)(eff) values are estimated to be about 1 kOe smaller than intrinsic values of shape anisotropy field. Saturation magnetization M-s in both kinds of metal particles is found to show almost the same value of about 1300 emu/cm(3). However, the switching field H-r(EA) normalized by H-k(plc)(efl) of the spindle-shaped particles is about 10-15% larger than that of the needle-shaped particles. Furthermore, the value of SFD of the spindle-shaped particles is about 20% smaller than that of the needle-shaped particles. The values of H-r(EA)/H-k(plc)(eff) and rotational hysteresis loss R-h in both kinds of metal particles are strongly related to the thickness of particles, however, significant differences in these relations between spindle-and needle-shaped metal particles were not observed. (C) 1998 Elsevier Science B.V. All rights reserved.
Latest developments of the spin-valve transistor 招待有り査読有り

JC Lodder, DJ Monsma, R Mollema, T Shimatsu, R Vlutters

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　175　(1-2)　159-159　1997年11月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/S0304-8853(97)00594-5 　

ISSN：0304-8853

詳細を見る詳細を閉じる

1 page
Development of the Spin-valve transistor 招待有り査読有り

D. J. Monsma, T. Shimatsu, R. Vlutters, E. G. Keim, R. H. Mollema, J. C. Lodder

IEEE Transactions on Magnetics　33　(5)　3495-3499　1997年7月

DOI： 10.1109/20.619478 　
Activation volume of FePt-TaN nanocrystalline thin films with high coercivity 査読有り

T. Shimatsu, E. G. Keim, T. Bolhuis, J. C. Lodder

Journal of the Magnetics Society of Japan　21　(S2)　313-316　1997年

DOI： 10.3379/jmsjmag.21.S2_313 　

詳細を見る詳細を閉じる

PMRC 1997
Effects of grain size and intergranular coupling on recording characteristics in CoCrTa media 査読有り

H Sato, A Kikuchi, J Nakai, H Mitsuya, T Shimatsu, M Takahashi

IEEE TRANSACTIONS ON MAGNETICS　32　(5)　3596-3598　1996年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.538701 　

ISSN：0018-9464

詳細を見る詳細を閉じる

The effects of grain size on intergranular magnetostatic coupling and on recording property are discussed for the Co85.5Cr10.5Ta4 and Co78Cr17Ta5 thin film media fabricated under the ultra clean sputtering process (UC-process). S/N-m increases not only with the increment in H-c/H-k(grain) but also with the decrement in the grain diameter in both CoCrTa media. In the media with high H-c/H-k(grain) value more than 0.35, S/N-m drastically increases with decrease in the grain diameter, which corresponds to the decrease in the dispersion of magnetic field strength from recorded bits. To maintain high H-c/H-k(grain) value more than 0.35 even in the media with small grain size below 10 nm, the selection of alloy composition which gives a small 4 pi M(s)/H-k(grain) value of less than 1.0 is required.
Dependence of media noise on grain size and intergranular coupling in thin‐film media 査読有り

Akira Kikuchi, Shinya Kawakita, Junichi Nakai, Takehito Shimatsu, Migaku Takahashi

Journal of Applied Physics　79　(8)　5339-5341　1996年4月
出版者・発行元：None
DOI： 10.1063/1.361371 　

ISSN：0021-8979
Effect of Pt on the magnetic anisotropy and intergranular exchange coupling in (Co86Cr12Ta2)(100-x)Pt-x and (Co62.5Ni30Cr7.5)(100-x)Pt-x thin-film media 査読有り

T Shimatsu, DD Djayaprawira, M Takahashi, T Wakiyama

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　155　(1-3)　246-249　1996年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(95)00639-7 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The effect of Pt on the magnetic anisotropy of grains and intergranular exchange coupling in (Co86Cr12Ta2)(100-x)Pt-x (x = 1-8) and (Co62.5Ni30Cr7.5)(100-x)Pt-x (x = 0-16) thin-film media has been investigated. In both kinds of media, the magnetocrystalline anisotropy field of the grains, H-k(grain), increases to twice as large as that at x = 0 by increasing x to about 9 at%. This is caused mainly by an increase in the magnetocrystalline anisotropy of the grains. The coercive force H-c increases with increasing Pt content, due mainly to the increase in H-k(grain), although H-c/H-k(grain) gradually decreases with increasing Pt in these media. In the CoCrTaPt media, the decrease in H-c/H-k(grain) with increasing Pt is caused mainly by an increase in the strength of the intergranular exchange coupling. In the CoNiCrPt media, the change in the c-axis direction from in-plane to normal with increasing Pt is suggested to play a major role in the reduction of H-c/H-k(grain).
Intergranular magnetic coupling in CoNiCrPt and CoCrTaPt thin-film media characterized by the temperature dependence of the rotational hysteresis loss 査読有り

T Shimatsu, DD Djayaprawira, A Endo, N Iwata, M Takahashi, T Wakiyama

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　155　(1-3)　242-245　1996年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(95)00747-4 　

ISSN：0304-8853

詳細を見る詳細を閉じる

In order to characterize intergranular magnetic coupling in (Co86Cr12Ta2)(100-x)Pt-x (x = 0 and 9) and (Co62.5Ni30Cr7.5)(100-x)Pt-x (x = 0 and 14) thin-film recording media, the temperature dependence of the rotational hysteresis loss has been examined. In all media, the coercive force H-c(T) gradually decreases to about half the value attained at 25 degrees C by increasing the measuring temperature T to about 300 degrees C without a change in the microstructure. In CoNiCr, CoNiCrPt and CoCrTaPt media, the decrease in H-c(T) with increasing T corresponds directly to the decrease in the magnetocrystalline anisotropy field of the grains, H-k(grain). In contrast, in CoCrTa media, H-c(T)/H-k(grain)(T) gradually decreases with increasing T. This decrease in H-c(T)/H-k(grain)(T) is suggested to be caused mainly by the increase in 4 pi M(s)(T)/H-k(grain)(T). This means that the intergranular magnetostatic coupling strongly affects the magnetic properties of the CoCrTa media examined here due to the low intergranular exchange coupling.
Intergranular coupling and recording properties of CoCrTa and CoNiCr thin-film media fabricated using an ultraclean sputtering process 査読有り

A Kikuchi, Okamoto, I, J Nakai, S Kawakita, T Shimatsu, M Takahashi

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　155　(1-3)　238-241　1996年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(95)00746-6 　

ISSN：0304-8853

詳細を見る詳細を閉じる

Magnetic properties, microstructure and their effect on media noise in Co85.5Cr10.5Ta4 and Co62.5Ni30Cr7.5 thin-film media fabricated using an ultraclean (UC) sputtering process are discussed as a function of the thickness of the Cr underlayer. By applying the UC process, high H-c values are realized even in these media with extremely thin Cr underlayers. In UC-CoCrTa, a high H-c of about 1.5 kOe remains even at a Cr thickness of 2.5 nm. The formation of a Cr segregated grain boundary structure is strongly enhanced by applying the UC process, which reduces the intergranular exchange coupling in these media. High S/N-m ratios are obtained even in CoNiCr media due to the remarkable decrease in intergranular exchange coupling. In the media with grains sufficiently separated by the segregated grain boundary, the reduction of the grain size with decreasing Cr thickness is found to be most effective for the improvement of S/N-m.
Microstructure and intergranular coupling in CoCrTa thin-film media fabricated using an ultraclean sputtering process 査読有り

J Nakai, A Kikuchi, K Nakatani, M Hirasaka, T Shimatsu

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　155　(1-3)　234-237　1996年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(95)00745-8 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The microstructure and intergranular coupling in Co85.5Cr10.5Ta4 and Co78Cr17Ta5 media fabricated using an ultraclean (UC) process are discussed in relation to the thickness of the Cr underlayer. The purification of the deposition atmosphere by applying the UC process is found to be most effective for deriving high H-c in both media. In UC-Co78Cr17Ta5, a high H-c of about 2.1 kOe remains even at a Cr thickness of 2.5 nm, With the UC process the Cr segregated grain boundary structure is enhanced even in media with thin Cr underlayers, which causes a remarkably low intergranular exchange coupling, The increase in the strength of intergranular magnetostatic coupling due to the grain size reduction strongly influences the reduction in H-c/H-k(grain) with decreasing Cr thickness, In UC-Co78Cr17Ta5 with extremely thin Cr underlayers, the sufficiently segregated grain boundary structure and the intrinsically low intergranular magnetostatic coupling are responsible for the realization of very high H-c/H-k(grain).
Effect of surface cleanness on the magnetic properties of CoNiCr and CoCrTa thin-film media fabricated using an ultraclean sputtering process 査読有り

S Kawakita, T Sakurai, A Kikuchi, T Shimatsu, M Takahashi

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　155　(1-3)　172-175　1996年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(95)00629-X 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The correlation between the cleanness of the substrate surface and magnetic properties is discussed for thin-film media fabricated using an ultraclean (UC) sputtering process. Only slight dry-etching of the substrate surface (etched depth about a few Angstrom) just before film deposition results in an increase in H-c, especially in media with thin Cr and magnetic layers. The removal of the adsorbed oxygen impurities on the substrate surface by slight dry-etching in the UC process, was found to cause the increase in H-c. It is suggested that the re-adsorption of gas impurities makes it impossible to improve magnetic properties by dry-etching in the normal sputtering process. Furthermore, it is clarified that the inducement of uniaxial magnetic anisotropy due to the texture of the substrate surface is strongly connected with the adsorption of gas impurities on the substrate surface.
EXTREMELY CLEAN SPUTTERING PROCESS AND MICROSTRUCTURAL PROPERTIES OF NI-FE FILMS FABRICATED BY THIS PROCESS 査読有り

K OKUYAMA, T SHIMATSU, S KUJI, M TAKAHASHI

IEEE TRANSACTIONS ON MAGNETICS　31　(6)　3838-3840　1995年11月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.489789 　

ISSN：0018-9464

詳細を見る詳細を閉じる

A specialized sputtering machine which enables the film deposition in the extremely clean atmosphere (XC-process) was newly constructed. Excellent base pressure less than 8X10(-12) Torr, which corresponds to about 1x10(-8) Torr 1/sec in the build up rate, succeed in realization in the process chamber. By use of both this new sputtering chamber and highly purified Ar gas with large amount of now rate, the very low impurity level during deposition is realized in the XC-process. This impurity level is about 4 orders lower than that of the normal sputtering process. By applying the XC-process to the fabrication of Ni-Fe films, grain size remarkably increases, and the highly coherent (111) crystal plane with lower fault density forms continuously from initial layer to the top of the films.
EFFECT OF MICROSTRUCTURE ON MEDIA NOISE OF COCRTA THIN-FILM MEDIA FABRICATED UNDER ULTRA CLEAN SPUTTERING PROCESS 査読有り

J NAKAI, M KUWABARA, A KIKUCHI, T SAKURAI, T SHIMATSU, M TAKAHASHI

IEEE TRANSACTIONS ON MAGNETICS　31　(6)　2833-2835　1995年11月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.490167 　

ISSN：0018-9464

詳細を見る詳細を閉じる

Ultra clean sputtering process (UC-process) was introduced In the fabrication of Co85.5Cr10.5Ta4/Cr thin film media Magnetic properties, microstructure and their effect on media noise are discussed against the thickness of Cr underlayer. By applying the UC-process, coercive force H-c shows high values of about 2.3 kOe isotropically until 10 nm in Cr thickness. High H-c of about 1.5 kOe remains at even 2.5 nm. UC-process is found to enable the enhancement of the formation of Cr segregated grain boundary structure, which reduces intergranular exchange coupling even in the media with 2.5 nm in Cr thickness. The ratio of readback signal to media noise S/Nm gradually increases with decreasing Cr thickness, and shows the highest value at 2.5 similar to 5 nm. In the media with sufficiently separated grains by segregated grain boundaries, the reduction of the grain size with decreasing Cr thickness is found to be most effective for the improvement of S/Nm.
CONTROL OF MAGNETIC-PROPERTIES AND MICROSTRUCTURE OF THIN-FILM RECORDING MEDIA UNDER ULTRACLEAN SPUTTERING PROCESS 査読有り

T SHIMATSU, M TAKAHASHI

IEICE TRANSACTIONS ON ELECTRONICS　E78C　(11)　1550-1556　1995年11月
出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG
ISSN：0916-8524

eISSN：1745-1353

詳細を見る詳細を閉じる

The ultraclean sputtering process (UC-process) was newly introduced in the fabrication of Co62.5Ni30Cr7.5 and Co85.5Cr10.5Ta4 thin film media to establish a new concept in controlling microstructure. UC-process enables the realization of high coercive force H-c up to 2.7-3 kOe in both CoNiCr and CoCrTa media (15/50 nm magnetic/Cr thicknesses) without the decrement of saturation magnetization. The purification of the atmosphere during sputtering and the removal of the adsorbed oxygen impurity on the substrate surface play important roles in obtaining high H-c by applying the UC-process. This high H-c is mainly due to the realization of large magnetocrystalline anisotropy field of grains H-k(grain) and low intergranular exchange coupling. UC-process realizes the adequate separation of grains by segregated grain boundaries even in media with thin Cr thickness of 2.5 nm, and enables grain size reduction without the remarkable increment in intergranular exchange coupling. In these media, the reduction of the grain size is most effective for the improvement of readback signal to media noise ratio S/Nm. In the media with grains sufficiently separated by segregated grain boundaries fabricated by the UC-process, control of grain size reduction and further increase in H-c/H-k(grain) value through the decrement in intergranular magnetostatic coupling are required to obtain higher S/Nm value.
クリーン化プロセスと磁気記録薄膜媒体査読有り

高橋研, 島津武仁

日本応用磁気学会誌　19　(5)　857-863　1995年10月

詳細を見る詳細を閉じる

トピックス
HIGH COERCIVE FORCE AND LOW INTERGRANULAR COUPLING IN THIN-FILM MEDIA FABRICATED UNDER THE ULTRA CLEAN SPUTTERING PROCESS 招待有り査読有り

T SHIMATSU, M TAKAHASHI

MATERIALS CHEMISTRY AND PHYSICS　41　(2)　134-140　1995年7月
出版者・発行元：ELSEVIER SCIENCE SA LAUSANNE
DOI： 10.1016/0254-0584(95)80018-2 　

ISSN：0254-0584

詳細を見る詳細を閉じる

The ultra clean sputtering process (UC process) was newly introduced in the fabrication of Co62.5Ni30Cr7.5 and Co85.5Cr10.5Ta4 thin film media to establish the new concept of controlling the microstructure. By applying the UC process, extremely high H-c values of up to 3 kOe were realized without decreasing the saturation magnetization in both kinds of media. A high H-c value was derived even in the media with very thin Cr underlayers. Magnetic torque analysis has revealed that the magnetocrystalline anisotropy field of grains, H-k(grain), is about 20-50% larger than that in the normally processed media, which is one of the dominant factors in realizing high H-c values. The realization of large H-k(grain) values was found to be mainly caused by the decrease in the Cr content of the grains. The enhancement of the homogeneously segregated grain boundary structure, which corresponds to a decrease in the intergranular exchange coupling, was also found to induce high H-c values in these media. This desired segregated structure was observed even in the media with an extremely thin Cr underlayer of 2.5 nm. The low intergranular coupling realized induced very low media noise even in the CoNiCr media. The UC process is concluded to be an essential technology for fabrication of high density thin film recording media.
Co-Fe-Ta-N薄膜の磁気異方性と軟磁気特性査読有り

島津武仁, 木村亘, 高橋研, 脇山徳雄

日本応用磁気学会誌　18　(2)　299-302　1994年4月

DOI： 10.3379/jmsjmag.18.299 　
(Co86Cr12Ta2)100-xPtx薄膜媒体の磁気異方性と粒間相互作用査読有り

島津武仁, 横田慎一, ダビッド D, 高橋研, 脇山徳雄

日本応用磁気学会誌　18　(2)　89-94　1994年4月

DOI： 10.3379/jmsjmag.18.89
Soft Magnetic Properties and Anisotropy of Co-Fe-Ta-N Films 査読有り

T. Shimatsu, W. Kimura, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　9　(6)　132-137　1994年

DOI： 10.1109/TJMJ.1994.4565970 　

ISSN：0882-4959

詳細を見る詳細を閉じる

This paper discusses the correlation between soft magnetic properties and microscopic magnetic structure in Co-(0–6 at%) Fe-(7–10 at%) Ta-N nanocrystalline films. Increasing the Fe content improves the soft magnetic properties of the films by decreasing the local anisotropy fluctuation. The temperature dependence of the coercive force indicates that the decrease in the magnetocrystalline anisotropy at room temperature due to the increase in Fe content plays an important role in decreasing the local anisotropy fluctuation. Furthermore, with increasing Fe content the film magnetostriction decreases, which suggests that the magnitude of the linear magnetostriction decreases. On the other hand, the uniaxial magnetic anisotropy energy Ku is reversibly induced by magnetic annealing in all films. As the Fe content is increased from 0 to 6 at% the magnitude of Ku gradually rises, and the Ku of films containing 6 at% Fe is about twice as large as that of films not containing Fe. © 1994 IEEE.
Magnetic Anisotropy and Intergranular Magnetic Coupling in (Co86Cr12Ta2)100-xPtx Thin Film Media 査読有り

T. Shimatsu, S. Yokota, D. D. Djayaprawira, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　9　(4)　34-40　1994年

DOI： 10.1109/TJMJ.1994.4565889 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Experimental characterization of the magnetic anisotropy field of grains Hkgrain, and the intergranular magnetic coupling in (Co86Cr12Ta2)100-xPtx thin film media was carried out by analyses of the magnetic torque and ΔM plot. The magnitude of Hkgrain gradually increases from about 4 kOe to around 8 kOe with increasing Pt content up to 8 at%, mainly because of the increase in magnetocrystalline anisotropy. On the other hand, the ratio of the coercive force Hc to Hkgrain changes from about 0.2 to about 0.3, depending on the Pt content and substrate temperature at the time of the film's fabrication. It was clarified that the difference of the ratio of Hc to Hkgrain in the examined media depends mainly on the difference in the strength of the intergranular exchange coupling. On the other hand, it is suggested that the knowledge of Hkgrain should be taken into account, in order to clarify how much the intergranular magnetic coupling influences the coercive force through analysis of ΔM plot. © 1994 IEEE
Experimental Characterization of Intergranular Exchange Coupling in CoCrTaPt and CoNiCrPt Thin Film Media 査読有り

T. Shimatsu, D. D. Djayaprawira, M. Takahashi, T. Wakiyama

Journal of the Magnetics Society of Japan　18　(S1)　269-274　1994年

DOI： 10.3379/jmsjmag.18.S1_269 　

詳細を見る詳細を閉じる

PMRC 1994, JST.JSTAGE/jmsjmag/18.S1_269
EXPERIMENTAL CHARACTERIZATION OF MAGNETIC ANISOTROPY AND INTERGRANULAR INTERACTION FOR THIN FILM MEDIA 招待有り査読有り

T SHIMATSU, M TAKAHASHI, M SUEKANE, M MIYAMURA, K YAMAGUCHI, H YAMASAKI

ADVANCED MATERIALS '93, II - A & B　15　(A & B)　777-782　1994年
出版者・発行元：ELSEVIER SCIENCE PUBL B V
CoCrTa/Cr薄膜媒体の磁気異方性の評価と磁気特性査読有り

島津武仁, 御手洗和彦, 小林正人, 高橋研, 脇山徳雄

日本応用磁気学会誌　17　(2)　83-88　1993年4月

DOI： 10.3379/jmsjmag.17.83 　
Fe系針状粒-塗布型媒体の磁気異方性と磁気特性査読有り

井垣通人, 横田真一, 国井誠, 島津武仁, 高橋研

日本応用磁気学会誌　17　(2)　77-82　1993年4月

DOI： 10.3379/jmsjmag.17.77 　
Co-Ta-N薄膜の磁気的微細構造と軟磁気特性査読有り

島津武仁, 木村亘, 佐藤和幸, 荘司弘樹, 高橋研, 脇山徳雄

日本応用磁気学会誌　17　(2)　327-332　1993年4月

DOI： 10.3379/jmsjmag.17.327 　
MAGNETIC EVALUATION OF INTERGRANULAR INTERACTIONS IN THIN-FILM MEDIA BY ROTATIONAL HYSTERESIS LOSS ANALYSIS 査読有り

M TAKAHASHI, T SHIMATSU, M SUEKANE, M MIYAMURA, K YAMAGUCHI, H YAMASAKI

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　120　(1-3)　229-231　1993年3月
出版者・発行元：ELSEVIER SCIENCE BV
DOI： 10.1016/0304-8853(93)91329-6 　

ISSN：0304-8853

詳細を見る詳細を閉じる

Magnetic torque analysis has been carried out for CoNiPt, CoCrTa/Cr and CoCrPt/Cr thin-film media. The magnetic field H(k)grain, where the rotational hysteresis loss vanishes, remained almost constant in each material independent of the coercive force H(c). Only in the CoCrTa media no clear correlation between the rotational hysteresis integral and H(c) was observed.
A Study on the Magnetic Microstructure of CoCrTa/Cr Film Media, Using Rotational Hysteresis Loss Analysis 査読有り

T. Shimatsu, K. Mitarai, M. Kobayashi, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　8　(9)　578-584　1993年

DOI： 10.1109/TJMJ.1993.4565700 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Rotational hysteresis loss analysis was carried out for CoCrTa/Cr thin film media fabricated on glass substrate, to evaluate the influence of the microstructure on the media's magnetic properties. Hkgrain, defined as the magnetic field at which the rotational hysteresis loss vanishes, remained at almost a constant value of about 4.0 kOe, independent of the values of the coercive force. It is considered that Hkgrain almost corresponds to the magnitude of the uniaxial magnetic anisotropy field of the grains, and that the coercive force is mainly determined by the degree of intergranular magnetic coupling interaction. In all the films examined, Hc was mainly determined by the switching of magnetization, independently of the degree of intergranular coupling. Calculated results suggest a possibility that, in CoCrTa films consisting of large grains, the magnetization in each grain changes direction as a result of incoherent magnetization switching. © 1993, IEEE.
Study on Magnetic Anisotropy for Fe Based Particulate Medium 査読有り

M. Igaki, S. Yokota, M. Kunii, T. Shimatsu, M. Takahashi

IEEE Translation Journal on Magnetics in Japan　8　(11)　742-749　1993年

DOI： 10.1109/TJMJ.1993.4565739 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The rotational hysteresis loss of MP tapes was analyzed in order to evaluate the magnitude of the magnetic anisotropy of metal particles and to clarify the effect of the degree of preferred particle orientation on their magnetic properties. Taking account of the magnetostatic interactions among particles, it is shown that the mean value of the magnetic anisotropy of metal particles is 7.7 kOe. Furthermore, it is thought that the mean value of the saturation magnetization inside the particles is about 1270 emu/cc. The ratio of Hk(2θ) to Hkptc is the key to evaluating the degree of the preferred particle orientation. Here Hk(2θ) is defined as the macroscopic anisotropy field, which is equivalent to the macroscopic uniaxial magnetic anisotropy in the tape plane. It was established that there are correlations between Hk(2θ)/Hkptc and the squareness of the magnetization curve, the coercive force, and the remanent coercive force. © 1993 IEEE
Study on the Magnetic Microstructures for CoNiPt Thin Film Media by Rotational Hysteresis Loss Analysis 査読有り

M. Suekane, M. Miyamura, T. Shimatsu, M. Takahashi

IEEE Translation Journal on Magnetics in Japan　8　(6)　388-395　1993年

DOI： 10.1109/TJMJ.1993.4565648 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The magnetic microstructures in CoNiPt thin film media with coercivities ranging from 800 Oe to 1800 Oe were studied through rotational hysteresis loss analyses. In order to investigate the mechanism for the observed increase in coercivity, Hc was analyzed as a function of Hk(2θ), Hkgrain and Hp, determined by magnetic torque measurements. Here Hk(2θ) is the macroscopically induced uniaxial anisotropy field in the film plane, Hkgrain is the magnetic field for which the rotational hysteresis loss Wr vanishes in the high magnetic field region, and Hp is the magnetic field at which Wr is maximum. According to the results, Hc increases with Hp, remaining slightly higher than Hp, while Hk(2θ) and Hkgrain showed no systematic change and remained almost constant. These experimental facts suggest that Hc for these samples is mainly determined by the magnetization reversal of exchange-coupled crystallites, and Hc increases as a consequence of the reduction of intergranular exchange coupling. This behavior corresponds closely to the reduction in medium noise. © 1993 IEEE
Soft Magnetic Properties and Microstructure of Co-Ta-N Films 査読有り

T. Shimatsu, W. Kimura, K. Satoh, H. Shoji, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　8　(12)　927-933　1993年

DOI： 10.1109/TJMJ.1993.4565774 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Co-(0 to 15 at%)Ta-N sputtered films were studied in order to clarify the correlation between the structure, induced magnetic anisotropy, local anisotropy fluctuation, and soft magnetic properties. The results for electrical resistivity and film magnetostriction indicate that the temperature Txl at which Co crystallites are formed from an amorphous structure is lower than the temperature at which crystallites of Ta-nitrides are formed. The difference was 150°C for Co-15 at% Ta-N films. A large uniaxial magnetic anisotropy was induced at Txl by annealing in a magnetic field, and even after crystallization, a uniaxial anisotropy of magnitude 2xl03 erg/cc could be reversibly induced by annealing in a magnetic field. © 1993 IEEE
トルク解析による磁気記録媒体の磁気異方性と磁化反転機構の評価査読有り

島津武仁, 高橋研

日本応用磁気学会誌　17　(S2)　255-262　1993年
出版者・発行元：社団法人日本磁気学会
DOI： 10.3379/jmsjmag.17.S2_255 　

ISSN：0285-0192

詳細を見る詳細を閉じる

PMRC 1993
MAGNETIZATION REVERSAL MECHANISM EVALUATED BY ROTATIONAL HYSTERESIS LOSS ANALYSIS FOR THE THIN-FILM MEDIA 査読有り

M TAKAHASHI, T SHIMATSU, M SUEKANE, M MIYAMURA, K YAMAGUCHI, H YAMASAKI

IEEE TRANSACTIONS ON MAGNETICS　28　(5)　3285-3287　1992年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.179785 　

ISSN：0018-9464

詳細を見る詳細を閉じる

In the present study. rotational hysteresis loss analysis is carried out for CoCrTa, CoNiPt and CoCrPt thin film media to evaluate the influence of microstructure on coercive force through the measurement of magnetic anisotropy. In each media, the magnitudes of H(k)grain defined as a magnetic field where rotational hysteresis loss W(r) diminishes remain almost a constant value independently of the values of coercive force. With increasing coercive force, the magnitude of coercive force gradually becomes smaller than that of switching field of magnetization H(p) evaluated by torque analysis. Through the analysis of H(k)grain and H(p), it is suggested that the coercive force in each examined media is strongly dependent on the degree of intergranular exchange coupling and/or magnetostatic interactions. While, in CoNiPt and CoCrPt media, coercive force has a dependence on rotational hysteresis integral R(h), however, in CoCrTa films, any correlation between them was not observed.
CoNiPt薄膜記録媒体の回転ヒステリシス損失解析による磁気的微細構造の評価査読有り

末包通信, 宮村賢郎, 島津武仁, 高橋研

日本応用磁気学会誌　16　(4)　655-660　1992年8月

DOI： 10.3379/jmsjmag.16.655 　
Magnetic Properties of Fe–Co–(Zr, Ta) Films Fabricated in Ar+N2 Plasma 査読有り

T. Shimatsu, H. Uwazumi, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　7　(4)　301-305　1992年

DOI： 10.1109/TJMJ.1992.4565383 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The possibility of realizing soft magnetic properties in 40 wt% Co-Fe alloy films with large magnetostriction constants, prepared by sputtering in Ar+N2 plasma, is examined. The value of Hc along the hard-axis direction of magnetization was about 10 Oe on annealing at 500°C. The soft magnetic properties of these films are determined primarily by lattice strain rather than by a macroscopically induced uniaxial magnetic anisotropy Ku. The calculated magnetic anisotropy energy U in individual grains, taking account of the magnetoelastic energy, drastically increases with slight increases in the lattice strain. Therefore, in order to obtain excellent soft magnetic properties, lattice strain relaxation to less than 0.1% is important. © 1992 IEEE
Soft Magnetic Properties for Fe–B Films Sputtered in Ar+N2 Plasma 査読有り

T. Shimatsu, Y. Sakai, M. Takahashi, T. Wakiyama, K. Hiraga

IEEE Translation Journal on Magnetics in Japan　7　(2)　103-112　1992年

DOI： 10.1109/TJMJ.1992.4565341 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Fe-B films sputtered in Ar+N2 plasma were investigated in order to obtain film with high initial permeability. Importance was placed on elucidation of the relation between the initial permeability μi and parameters of the film structure such as the phase, grain size, and lattice strain. Fe-B (1 to 4 at% B) films sputtered in Ar+5%N2 plasma exhibit a high μi of about 2000 after annealing at 400 °C, and about 1000 after annealing at 500°C. The results of X-ray and electron diffraction patterns indicate that films with high μi consist of the α phase. By comparing this with results for Fe-N films, it is suggested that the high μi of Fe-B-N films is caused by the reduction of grain sizes and induced lattice strain, as well as other metallurgical structures such as in homogeneities. © 1992 IEEE
Fabrication and Magnetic Properties of Fe Thin Films on a Substrate Excited by SAW 査読有り

M. Takahashi, T. Tanaka, T. Shimatsu, M. Uemura, T. Wakiyama, J. Yamada, T. Shibata

IEEE Translation Journal on Magnetics in Japan　7　(1)　81-87　1992年

DOI： 10.1109/TJMJ.1992.4565330 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Fe films of thickness 300Å were prepared by electron beam evaporation and dc magnetron sputtering onto LiNbO3 single-crystal substrate excited by surface acoustic waves (SAWs) at 45 MHz. A biaxial anisotropy was induced in the film plane for evaporated films with the substrate excited at 8 V, but was not induced at all in sputtered films. The saturation magnetization Ms of the evaporated films increased with increasing excitation voltage, and reached the bulk value at an excitation voltage of 8 V. However, the Ms of sputtered films was not changed by SAW excitation. The density of evaporated films was close to the density of bulk Fe at an excitation voltage of 8 V. This fact shows that the structure of evaporated films changed from a porous to a dense structure with SAW excitation. Further, the film surface became smooth when the substrate was excited. ©1992 IEEE
Soft magnetism of nanocrystalline films – Recent advances and physics – 招待有り査読有り

M. Takahashi, T. Shimatsu, H. Shoji

Digests of the 6th International Conference on Ferrites, ICF 6　446　1992年
Ar+N2プラズマ中で作製したFe-B薄膜の軟磁気特性査読有り

高橋研, 藤田昭彦, 島津武仁, 脇山徳雄, 山田純, 芝隆司

日本応用磁気学会誌　15　(2)　351-356　1991年4月

DOI： 10.3379/jmsjmag.15.351
ガラス基板上に作製したCoNiCr薄膜記録媒体の構造および磁気特性に及ぼす Cr下地の効果査読有り

堀川順一, 小林正人, 諸石圭二, 島津武仁, 高橋研, 越阪部基延, 中山伸, 山口洋一, 生嶋明, 脇山徳雄

日本応用磁気学会誌　15　(2)　89-92　1991年4月

DOI： 10.3379/jmsjmag.15.89 　
弾性表面波で励起された基板上へのFe薄膜の作製とその磁性査読有り

高橋研, 田中寿郎, 島津武仁, 植村誠, 脇山徳雄, 山田純, 芝隆司

日本応用磁気学会誌　15　(2)　323-326　1991年4月

DOI： 10.3379/jmsjmag.15.323 　
Fe-Ni,Ni-Co,Fe-Co二元合金膜の磁気光学効果査読有り

佐藤友章, 島津武仁, 宮原鉄洲, 宮崎照宣

日本応用磁気学会誌　15　(2)　197-200　1991年4月

DOI： 10.3379/jmsjmag.15.197 　
窒素添加雰囲気中で作製されたFe-Co-(Zr,Ta)薄膜における軟磁性導出の可能性査読有り

島津武仁, 上住洋之, 高橋研, 脇山徳雄

日本応用磁気学会誌　15　(2)　375-378　1991年4月

DOI： 10.3379/jmsjmag.15.375 　
Effects of Underlayer on Magnetic Properties of CoNiCr Thin Film Media Sputtered on Glass Substrates 査読有り

J. I. Horikawa, M. Kobayashi, K. Moroishi, T. Shimatsu, M. Takahashi, K. Osakabe, S. Nakayama, Y. Yamaguchi, A. J. Ikushima, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　6　(8)　641-647　1991年

DOI： 10.1109/TJMJ.1991.4565228 　

ISSN：0882-4959

詳細を見る詳細を閉じる

CoNiCr/Cr films were sputtered onto polished glass at temperatures Ts ranging from 25 to 400°C/ and their magnetic properties were investigated in connection with their micro-structure. Hc was found to increase with increasing Ts while sputtering CoNiCr/Cr films, which consisted mainly of an h.c.p. phase. Analytical transmission electron microscopy revealed that the underlayer Cr diffused into grain boundaries of the CoNiCr layer, and at higher Ts, into individual CoNiCr grains. Torque loss analyses were performed to determine the magnetic isolation among CoNiCr grains. The uniaxial magnetic anisotropy field for individual grains determined experimentally, Hkgrain (exp), was found to increase with increasing Ts. Metalographical change promoted magnetic isolation among h.c.p. CoNiCr grains, and as a result, the microscopic demagnetizing field in each CoNiCr grain increased. This conclusion is well supported by the experimental results of the torque loss analysis in this work. © 1991 IEEE
Soft Magnetic Properties of Ni-Fe-Nb Alloy Films with Nearly 50 wt% Ni Concentration 査読有り

Migaku Takahashi, H. Uwazumi, T. Shimatsu, T. Sato, Minoru Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　6　(2)　112-119　1991年

DOI： 10.1109/TJMJ.1991.4565120 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The relation between soft magnetic properties and local anisotropy fluctuation, which is strongly connected with the film micro structure, was systematically examined for Ni-Fe-Nb alloy films with nearly 50 wt% Ni. According to the micromagnetic ripple theory of Hoffmann, the effective magnetic anisotropy Ueff in each of the grains decreases drastically with increases in the number of grains N within the coupling volume. Experimental results showed that the local anisotropy fluctuation in Ni-Fe-Nb alloy films depends heavily on Ueff/Ku, and decreases with decreasing Ueff/Ku. Therefore, to realize high initial permeability in such films, it is necessary to increase N within the coupling volume by decreasing the grain size. In the cae of Ni-Fe-Nb alloy films, the grain size must be decreased to less than 200 Å in order to obtain a high initial permeability more than 2000. © 1991 IEEE
Fabrication and Magnetic Properties of Thin Films Sputtered on the Substrate Excited by SAW 査読有り

M. Takahashi, A. Fujita, T. Shimatsu, T. Wakiyama, J. Yamada, T. Shiba

IEEE Translation Journal on Magnetics in Japan　6　(2)　127-133　1991年

DOI： 10.1109/TJMJ.1991.4565122 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Permalloy films of thickness 300 Å were deposited by d.c. magnetron sputtering onto LiNbO3 single-crystal substrates excited by SAW (surface acoustic waves) at 45 MHz. Film structures, such as grain shapes and sizes were found to change drastically as functions of the excitation amplitude. Particularly when deposited at an excitation amplitude of 24 ÅQ-p, films consisted of very fine homogeneous grains and showed soft magnetic properties, namely a minimum coercive force. A uniaxial anisotropy was induced in the film plane in all films examined however, at the critical amplitude, the in-plane easy axis was found to change significantly. It was concluded that deposition of film onto substrates excited by SAW is a highly useful method for controlling the film microstructure and magnetic properties. © 1991 IEEE
Structure and Magnetic Properties for Fe-C Films Fabricated in Ar+N2 Plasma 査読有り

M. Takahashi, T. Shimatsu, Y. Sakai, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　6　(1)　71-77　1991年

DOI： 10.1109/TJMJ.1991.4565109 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The soft magnetic properties of Fe-C films sputtered in Ar+N2 plasma are examined, and the relations between the effective permeability μeff and metallurgical structure, such as grain size and lattice strain, are discussed. Excellent soft magnetic properties, with μeff = 1400, were obtained in Fe-1. 6 at% C-N films annealed at 300°C, at which temperature the martiensite phase (bct Fe-C) disappeared. From the X-ray diffracted line from the (110) crystal plane of α-Fe, it was found that the films consist of fine grains. This fact may suggest that the formation of iron nitride rather than Fe3C by annealing at 300°C plays an important role in forming the fine grain structure in films. In those films with a high μeff, the lattice spacing of the (110) crystal plane α-Fe is slightly (approximately 0.1%) expanded. These results suggest that the total magnetic anisotropy energy in the (110) plane of each of the α-Fe grains decreases owing to the induced magnetoelastic anisotropy due to tetragonal deformation. © 1991 IEEE
Magnetic Properties of Fe-Si-N Films Sputtered in (Ar+N2) Plasma 査読有り

M. Takahashi, H. Komaba, H. Shoji, T. Shimatsu, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　6　(1)　78-84　1991年

DOI： 10.1109/TJMJ.1991.4565110 　

ISSN：0882-4959

詳細を見る詳細を閉じる

Soft magnetic properties of Fe-Si alloy films sputtered in (Ar+N2) plasma are examined, and the relations between the permeability μeff and features of the metallurgical structure such as the lattice strain and grain size, are discussed. The total magnetic anisotropy in individual crystal grains was calculated for various Fe-Si alloys by considering the magnetoelastic energy due to the experimentally determined lattice strain. Experimentally obtained changes in μeff agreed well with the calculated change in total anisotropy as a function of Si concentration and N2 flow ratio. However, given the magnitude of μefff this composition dependence of the μeff vs. N2 flow ratio is clearly a function of the grain size. It was concluded that the soft magnetic properties of Fe-Si alloy sputtered films are related to both reduction of the total anisotropy due to lattice strain from the bcc to the bet structure, and also to the grain size. © 1991 IEEE
Magnetostriction and magnetic anisotropy for Fe based soft magnetic films 査読有り

T. Shimatsu, H. Shoji, M. Kyoho, M. Takahashi, T. Wakiyama

Journal of the Magnetics Society of Japan　15　(S2)　63-68　1991年

DOI： 10.3379/jmsjmag.15.S2_63 　

詳細を見る詳細を閉じる

PMRC 1991, JST.JSTAGE/jmsjmag/15.S2_63
Change of microscopical anisotropy on film thickness for Fe based soft magnetic films 査読有り

H. Shoji, Y. Sakai, T. Shimatsu, M. Takahashi, T. Wakiyama

Journal of the Magnetics Society of Japan　15　(S2)　561-566　1991年

DOI： 10.3379/jmsjmag.15.S2_561 　

詳細を見る詳細を閉じる

PMRC 1991, JST.JSTAGE/jmsjmag/15.S2_561
SOFT MAGNETIC-PROPERTIES AND MICROSTRUCTURES FOR THE FE BASED SPUTTERED FILMS WITH HIGH BS 招待有り査読有り

M TAKAHASHI, T SHIMATSU

MAGNETIC MATERIALS : MICROSTRUCTURE AND PROPERTIES　232　223-232　1991年
出版者・発行元：MATERIALS RESEARCH SOC
Soft magnetism of nanocrystalline Fe based sputtered films with high Bs 招待有り査読有り

Migaku Takahashi, T. Shimatsu

Journal of Magnetism and Magnetic Materials　101　(1-3)　11-15　1991年

DOI： 10.1016/0304-8853(91)90660-3 　

ISSN：0304-8853

詳細を見る詳細を閉じる

The physical origin of the high initial permeability, μi, in Fe based films with a large magnetocrystalline anisotropy and magnetostriction is systematically discussed in connection with the microstructure of the films. In order to decrease the local anisotropy fluctuation to determine μi, a decrease of the effective magnetic anisotropy, Ueff, of each grain mainly caused by sufficient reduction of the grain size is required. Induced uniaxial magnetic anisotropy energy, Ku, plays an important role to decrease Ueff through the micromagnetic interaction. The ratio of Ueff/Ku is proposed as the important key to analyze the magnetization process. The dependence of μi on Ku is classified concerning for Ueff/Ku. © 1991.
SOFT MAGNETIC-PROPERTIES OF FE-N AND FE-SI-N THIN-FILMS SPUTTERED IN (AR+N2) PLASMA 査読有り

M TAKAHASHI, H SHOJI, T SHIMATSU, H KOMABA, T WAKIYAMA

IEEE TRANSACTIONS ON MAGNETICS　26　(5)　1503-1505　1990年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.104425 　

ISSN：0018-9464
NEW THIN-FILM FABRICATION TECHNIQUE USING A SUBSTRATE EXCITED BY SAW 査読有り

M TAKAHASHI, A FUJITA, T SHIMATSU, T WAKIYAMA, J YAMADA, T SHIBA

IEEE TRANSACTIONS ON MAGNETICS　26　(5)　1453-1455　1990年9月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.104408 　

ISSN：0018-9464
Ni-Fe-Nb(50Ni-Fe組成)合金薄膜の軟磁気特性査読有り

高橋研, 上住洋之, 島津武仁, 佐藤武信, 高橋実, 脇山徳雄

日本応用磁気学会誌　14　(2)　305-308　1990年8月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.14.305 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The relation between soft magnetic properties and local anisotropy fluctuation, which is strongly connected with the microstructure of the films, was systematically examined for Ni-Fe-Nb alloy films with nearly 50 wt%Ni. According to the micromagnetic ripple theory by Hoffmann, effective magnetic anisotropy Ueff in each of the grains decreases drastically with increases in the number of grains N within the coupling volume. Experimental results show local anisotropy fluctuation for Ni-Fe-Nb alloy films strongly depends on Ueff/Ku, and it decreases with decreasing Ueff/Ku. Therefore, to realize high initial permeability in these films, it is necessary to increase N within the coupling volume by decreasing the size of the grains. In the case of Ni-Fe-Nb alloy films, decreasing the size of the grains less than 200Å to obtain high initial permeability more than 2000 is needed.
Ar+N2プラズマ中で作製されたFe-C薄膜の構造と磁性査読有り

高橋研, 島津武仁, 酒井泰志, 脇山徳雄

日本応用磁気学会誌　14　(2)　297-300　1990年8月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.14.297 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Soft magnetic properties for Fe-C films sputtered in Ar+N2 plasma were examined and a discussion was developed for the relations between effective permeability μeff and metallurgical structure such as grain size and lattice strain. Excellent soft magnetic properties, μeff=1400, were obtained in Fe-1.6 at%C-N films annealed at 300°C at which temperature martensite phase ((bct)Fe-C) disappeared. From the X-ray diffracted line from (110) crystal plane of α-Fe, it was found that films consists of fine grains. This fact might suggest that the formation of iron nitride rather than that of Fe3C by annealing at 300°C plays an important role in making the fine grains in films. In the films with high μeff, lattice spacing of (110) crystal plane of α-Fe is slightly expanded about 0.1%. These results suggest that total magnetic anisotropy energy in (110) plane in each α-Fe grains decreases by the induced magneto-elastic anisotropy due to tetragonal deformation.
(Ar+N2)プラズマ中で作製されたFe-Si-N薄膜の軟磁性査読有り

高橋研, 駒場博則, 荘司弘樹, 島津武仁, 脇山徳雄

日本応用磁気学会誌　14　(2)　301-304　1990年8月

DOI： 10.3379/jmsjmag.14.301
弾性表面波で励振された基板上への薄膜の作製とその磁性査読有り

高橋研, 藤田昭彦, 島津武仁, 脇山徳雄, 山田純, 芝隆司

日本応用磁気学会誌　14　(2)　323-326　1990年8月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.14.323 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Permalloy films of 300Å thickness were prepared by d.c. magnetron sputtering onto LiNbO3 single crystal substrate excited by SAW at 45 MHz. Film structure such as shapes and size of grains was found to be drastically changed as a function of excited amplitude. Especially in the case of 24Åo-p for excited amplitude, films consisted of very fine homogeneous grains and showed magnetic softness, namely minimum coercive force. Uniaxial anisotropy was induced in plane for all the films examined; however, in the critical excited amplitude mentioned above, a drastic change of the easy axis in plane was found. As a conclusion, film preparation onto the substrate excited by SAW is considered to be a highly useful method to control the microscopical film structure and also the magnetic properties.
Soft Magnetic Properties of Fe-Ni-Nb Alloy Films 査読有り

T. Shimatsu, M. Takahashi, H. Uwazumi, T. Sato, M. Takahashi, T. Wakiyama

IEEE Translation Journal on Magnetics in Japan　5　(7)　547-553　1990年

DOI： 10.1109/TJMJ.1990.4564141 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The relation between the soft magnetic properties and local anisotropy fluctuation measured by the dynamic differential susceptibility method in Fe-Ni-Nb alloy films was clarified and discussed in comparison with Fe-Si-Al alloy films. Fe-Ni-Nb alloy films with excellent soft magnetic properties, 5 MHz values of μ eff = 6500 for 1000 A thick films were obtained. For Fe-Si-Al alloy films, the magnitude of μeff = 6500 is proportional to 1/s2 (where S is a structure constant) and independent of the value of Hk, while for Fe-Ni-Nb alloy films, the value of S is about one-tenth of that in Fe-Si-Al alloy films, and the magnitude of μeff 6500 does not depend on S. Rather, this magnitude is dependent on the value of Hk, and is almost equal to 4 π Ms/Hk, obtained from a rotational magnetization model in a uniaxial single-domain particle. © 1990 IEEE
Soft Magnetic Properties of Fe–Al–Si and Fe–Ni–Nb Sputtered Alloy Films 査読有り

M. Takahashi, T. Sato, T. Shimatsu, M. Takahashi

IEEE Translation Journal on Magnetics in Japan　5　(1)　2-16　1990年

DOI： 10.1109/TJMJ.1990.4564097 　

ISSN：0882-4959
Soft Magretism of Crystalline Fe Based Alloy Sputtered Films (invited) 招待有り査読有り

Migaku Takahashi, T. Shimatsu

IEEE Transactions on Magnetics　26　(5)　1485-1490　1990年

DOI： 10.1109/20.104420 　

ISSN：1941-0069 0018-9464

詳細を見る詳細を閉じる

The physical origin of soft magnetic properties in Fe based alloy films with large magnetocrystalline anisotropy and magnetostriction are systematically examined. The relations between the microstructure of the film and soft magnetic properties are discussed for various kinds of Fe based alloy films such as Fe-N, Fe-Si-Al, Ni-Fe-Nb etc. fabricated by d.c. magnetron sputtering. Magnetic anisotropy dispersion has been analyzed based on the micromagnetic ripple theory proposed by H. Hoffmann. Analysis of dynamic differential susceptibility suggests that initial permeability is strongly related to the structure constant S, which must be reduced in order to realize high initial permeability. It has been demonstrated that the reduction of grain size and induced lattice deformation are very effective for decreasing the value of S with respect to controlling microstructure of the film. Several factors which must be taken in account for achieving high initial permeability in Fe based alloy films are proposed. © 1990 IEEE
Fe-Ni-Nb系合金薄膜の軟磁気特性査読有り

島津武仁, 高橋研, 上住洋之, 佐藤武信, 高橋実, 脇山徳雄

日本応用磁気学会誌　13　(2)　281-284　1989年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.13.281 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Relation between soft magnetic properties and local anisotropy fluctuation in Fe-Ni-Nb alloy films measured by the dynamic differential susceptibility method was clarified and discussed in comparison with Fe-Si-Al alloy films. In Fe-Ni-Nb alloy films, excellent soft magnetic properties, μeff=6500 at 5 MHz of 1000Å film thickness, were realized. In Fe-Si-Al alloy films, the magnitude of μeff is proportional to 1/√S (S: structure constant) and independent of the value of HK, while in Fe-Ni-Nb alloy films, the value of S is about one tenth of that in Fe-Si-Al alloy films, and the magnitude of μeff is not dependent on the value of S. Rather, this magnitude is dependent on the value of Hk, and is almost equal to 4πMs/Hk (obtained from a rotational magnetization model in a uniaxal single domain particle).
Fe/Co/ZrO積層薄膜の軟磁気特性査読有り

宮崎照宣, 佐藤文隆, 高橋研, 田中寿郎, 島津武仁

日本応用磁気学会誌　13　(2)　241-244　1989年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.13.241 　

ISSN：0285-0192

詳細を見る詳細を閉じる

The dependence of soft magnetic properties on the thickness and composition has been investigated for sputtered Fe-Co/ZnO multilayers. The coercivity decreases with the decrease in average size of crystallites D, in particular from 9 to 17 nm for all multilayers except Co/ZnO. Magnetic properties with Hc=160 A/m and μe(10 MHz)=800 are obtained for Fe/ZnO and 24Co-Fe/ZnO multilayers with D=2∼3 nm.
Local Anisotropy Fluctuation on the Permeability of Sputtered Sendust Alloy Films 査読有り

M. Takahashi, T. Shimatsu, H. Shoji, T. Wakiyama, N. Kato

IEEE Translation Journal on Magnetics in Japan　4　(10)　598-607　1989年

DOI： 10.1109/TJMJ.1989.4564066 　

ISSN：0882-4959

詳細を見る詳細を閉じる

The precise concentration dependence of μf f in films was clarified in the concentration area around bulk Sendust alloy. The method of dynamic differential susceptibility measurement proposed by Hoffman was applied to these films to evaluate magnetic inhomogeneities normally represented as magnetic skew and ripple. Influence of the local magnetic anisotropy on the μe f f of the films is discussed in detail. To realize excellent soft magnetic properties, especially at high frequencyf a high degree of preferred orientation of grains or of random orientation of grains is suggested. © 1989 IEEE
Effect of local anisotropy fluctuation on soft magnetic properties for Fe and Fe based alloy films 査読有り

T. Shimatsu, M. Takahashi, T. Wakiyama

Journal of the Magnetics Society of Japan　13　(S1)　577-583　1989年

DOI： 10.3379/jmsjmag.13.S1_577 　

詳細を見る詳細を閉じる

PMRC 1989, JST.JSTAGE/jmsjmag/13.S1_577
INFLUENCE OF LOCAL ANISOTROPY FLUCTUATION ON SOFT MAGNETIC-PROPERTIES OF THE SPUTTERED FE-SI-AL ALLOY-FILMS 査読有り

M TAKAHASHI, N KATO, T SHIMATSU, H SHOJI, T WAKIYAMA

IEEE TRANSACTIONS ON MAGNETICS　24　(6)　3084-3086　1988年11月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI： 10.1109/20.92342 　

ISSN：0018-9464
センダストスパッタ薄膜の磁気的微細構造と軟磁性査読有り

高橋研, 加藤暢昭, 島津武仁, 荘司弘樹, 脇山徳雄

日本応用磁気学会誌　12　(2)　305-310　1988年4月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.12.305 　

ISSN：0285-0192

詳細を見る詳細を閉じる

Precise concentration dependence of μeff in films was clarified in a concentration area around bulk Sendust alloy. The dynamic differential susceptibility measurement proposed by H. Hoffmann was applied to the same films to evaluate the magnetic inhomogeneities normally represented as magnetic skew and ripple. Influence of the local magnetic anisotropy on μeff of the films is discussed in detail. To realize excellent soft magnetic properties, especially at high frequency, a high degree of preferred orientation of grains or of random orientation of grains is suggested.
Fe-Al-Si及びFe-Ni-Nb合金スパッタ薄膜の軟磁性 : 画像情報記録

高橋研, 佐藤武信, 島津武仁, 高橋実

テレビジョン学会技術報告　12　(26)　1-10　1988年
出版者・発行元：一般社団法人映像情報メディア学会
DOI： 10.11485/tvtr.12.26_1 　
Effect of Local Anisotropy Fluctuation on the Permeability of Fe-Si-Al Sputtered Films 査読有り

M. Takahashi, T. Shimatsu, H. Shoji, T. Wakiyama, N. Kato

IEEE Translation Journal on Magnetics in Japan　3　(7)　593-594　1988年

DOI： 10.1109/TJMJ.1988.4563805 　

ISSN：0882-4959
Co-Zr-Mo-Niアモルファス薄膜の磁気的微細構造と軟磁性（動的微分磁化率の計測）査読有り

高橋研, 島津武仁, 島田寛, 脇山徳雄

日本応用磁気学会誌　11　(2)　275-278　1987年3月
出版者・発行元：The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.11.275 　

ISSN：0285-0192

詳細を見る詳細を閉じる

To evaluate the magnetic inhomogeneities normally represented as magnetic skew and ripple, a systematic experimental investigation was carried out using the dynamic differential susceptibility measurement proposed by H. Hoffmann for multilayered Co79Zr10Mo9Ni2 amorphous films. Influence of the local magnetic anisotropy on the effective permeability, μeff, of the films is broadly discussed in connection with the magnetic skew and ripple. The magnitude of the μeff at the low frequency region less than 1 MHz is strongly dependent on the degree of the long period fluctuation of the local magnetization (skew) and the magnitude of the anisotropy field. To realize excellent soft magnetic properties in films at high frequency (10 MHz), it is suggested that the decrement of the magnetic inhomogeneities due to the short period fluctuation of the local magnetization are important.
The effect of the local anisotropy fluctuation on the permeability for multilayered Co-Zr-Mo-Ni amorphous films 査読有り

M. Takahashi, T. Shimatsu, Y. Shimada, T. Wakiyama

Proceedings of the International Symposium on Physics of Magnetic Materials (World Scientific Publishing Co Pte Ltd.)　134-137　1987年

︎全件表示 ︎最初の5件までを表示

MISC 77

原子拡散接合法：光デバイス応用に向けた室温・低温接合技術招待有り

島津武仁, 魚本幸

月刊オプトロニクス2023年11月号　104-107　2023年11月
原子拡散接合法：無機薄膜（金属，酸化物，窒化物）を用いたガラス等の室温接合技術招待有り

島津武仁, 魚本幸

表面と真空　65　(10)　454-459　2022年10月10日
出版者・発行元：Surface Science Society Japan
DOI： 10.1380/vss.65.454 　

ISSN：2433-5835

eISSN：2433-5843
Co/Pt多層膜ナノドットのマイクロ波アシスト磁化反転における熱活性の影響 (マルチメディアストレージ)

水谷聡志, 菊池伸明, 畑山正寿, 岡本聡, 島津武仁

映像情報メディア学会技術報告 = ITE technical report　45　(14)　7-11　2021年6月
出版者・発行元：映像情報メディア学会
ISSN：1342-6893
原子拡散接合法：真空中の金属膜表面における原子再配列現象を利用した室温接合技術招待有り

島津武仁

真空ジャーナル　175　12-16　2021年1月
出版者・発行元：(一社)日本真空工業会

詳細を見る詳細を閉じる

特集セラミックスと異種材料の接合技術
マイクロ波アシスト磁化反転

菊池伸明, 岡本聡, 北上修, 島津武仁

まぐね　15　(2)　89-95　2020年4月
CoCrPtグラニュラー薄膜における磁性粒子間交換結合のマイクロ波アシスト磁化反転への影響 (マグネティックス研究会ナノスケール構造磁性体,磁性材料,磁気応用一般)

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

電気学会研究会資料. MAG = The papers of technical meeting on magnetics, IEE Japan　2019　(197)　13-17　2019年12月19日
出版者・発行元：電気学会
CoCrPtグラニュラ記録媒体のマイクロ波アシスト磁化反転実験 (磁気記録・情報ストレージ)

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報　119　(79)　9-14　2019年6月13日
出版者・発行元：電子情報通信学会
ISSN：0913-5685
CoCrPtグラニュラ記録媒体のマイクロ波アシスト磁化反転実験 (マルチメディアストレージ)

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

映像情報メディア学会技術報告 = ITE technical report　43　(15)　9-14　2019年6月
出版者・発行元：映像情報メディア学会
ISSN：1342-6893
マイクロ波アシスト磁気記録における磁化反転挙動 (磁気記録・情報ストレージ)

岡本聡, 菊池伸明, 北上修, 島津武仁

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報　118　(490)　33-36　2019年3月8日
出版者・発行元：電子情報通信学会
ISSN：0913-5685
マイクロ波アシスト磁気記録における磁化反転機構 (マグネティックス電子材料合同研究会光記録・磁気記録・一般)

岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会研究会資料. EFM　2019　(1)　33-36　2019年3月8日
出版者・発行元：電気学会
マイクロ波アシスト磁気記録における磁化反転機構 (マグネティックス電子材料合同研究会光記録・磁気記録・一般)

岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会研究会資料. MAG = The papers of technical meeting on magnetics, IEE Japan　2019　(14)　33-36　2019年3月8日
出版者・発行元：電気学会
Low Temperature Bonding for 3D Integration FOREWORD

Tadatomo Suga, Naoteru Shigekawa, Eiji Higurashi, Takehito Shimatsu, Masakazu Sugiyama, Hideki Takagi, Noriaki Toyoda

JAPANESE JOURNAL OF APPLIED PHYSICS　57　(2)　2018年2月
出版者・発行元：IOP PUBLISHING LTD
DOI： 10.7567/JJAP.57.02B001 　

ISSN：0021-4922

eISSN：1347-4065
双極子結合した積層磁性ドットによるマイクロ波アシスト実験 (マグネティックス研究会ナノスケール構造磁性体,光/熱・スピンデバイス,磁性材料,磁気応用一般)

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会研究会資料. MAG = The papers of technical meeting on magnetics, IEE Japan　2017　(138)　21-25　2017年11月16日
出版者・発行元：電気学会
薄いAu薄膜を用いたアルミ合金とCuの大気中の室温接合

阿部真帆, 魚本幸, 島津武仁

マイクロエレクトロニクスシンポジウム論文集　26　339-342　2016年9月8日
出版者・発行元：エレクトロニクス実装学会
薄いAu薄膜を用いたアルミ合金とステンレス合金の大気中の室温接合

魚本幸, 阿部真帆, 島津武仁

マイクロエレクトロニクスシンポジウム論文集　26　335-338　2016年9月8日
出版者・発行元：エレクトロニクス実装学会
原子拡散接合法によるセラミックスと異種材料との室温接合

島津武仁, 魚本幸

CERAMICS JAPAN　51　(2)　91-93　2016年2月1日
出版者・発行元：(公社)日本セラミックス協会
ISSN：0009-031X
物づくりと産学連携

島津武仁

エレクトロニクス実装学会誌　18　(7)　P7-P7　2015年11月1日
出版者・発行元：(社)エレクトロニクス実装学会
DOI： 10.5104/jiep.18.P7 　

ISSN：1343-9677
薄いAu薄膜を用いたFeバルク材の室温接合と接合性能

魚本幸, 島津武仁

マイクロエレクトロニクスシンポジウム論文集　25　289-292　2015年9月3日
出版者・発行元：エレクトロニクス実装学会
A Theoretical Study of Thermally Activated Magnetization Switching under Microwave Assistance 査読有り

H. Suto, K. Kudo, T. Nagasawa, T. Kanao, K. Mizushima, R. Sato, S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu

2015 IEEE MAGNETICS CONFERENCE (INTERMAG)　2015年
出版者・発行元：IEEE
a-Si, a-Ge薄膜を用いたウエハの室温接合と接合性能

魚本幸, 今一恵, 島津武仁

マイクロエレクトロニクスシンポジウム論文集　23　265-268　2013年9月12日
出版者・発行元：エレクトロニクス実装学会
放熱用金属バルク材料と電子デバイス用ウエハの大気中低温接合技術の開発

今一恵, 魚本幸, 島津武仁

マイクロエレクトロニクスシンポジウム論文集　23　143-146　2013年9月12日
出版者・発行元：エレクトロニクス実装学会
原子拡散接合法を用いたウエハの室温接合とデバイス応用

島津武仁, 魚本幸

精密工学会誌　79　(8)　710-713　2013年8月1日
出版者・発行元：公益社団法人精密工学会
DOI： 10.2493/jjspe.79.710 　

ISSN：0912-0289
原子拡散接合法によるウエハ室温接合技術とエタロンフィルタへの応用

島津武仁, 魚本幸, 今一恵, 若林小太郎, 大場健司, 古堅由紀子

OPTRONICS　32　(7)　88-92　2013年7月1日
出版者・発行元：（株）オプトロニクス社
C-7-2 パターン媒体の記録マージンに関する検討(C-7.磁気記録・情報ストレージ,一般セッション)

白幡一樹, 嵯峨秀樹, 三浦健司, 島津武仁, 青井基, 村岡裕明

電子情報通信学会総合大会講演論文集　2011　(2)　20-20　2011年2月28日
出版者・発行元：一般社団法人電子情報通信学会
金属薄膜を用いた原子拡散接合の開発

島津武仁, 魚本幸

まてりあ　49　(11)　521-527　2010年11月1日
出版者・発行元：(社)日本金属学会
DOI： 10.2320/materia.49.521 　

ISSN：1340-2625
新しい積層構造を用いた超高密度垂直磁気記録媒体

島津武仁, 青井基, 北上修

まてりあ　47　(5)　249-255　2008年5月
出版者・発行元：（社）日本金属学会
DOI： 10.2320/materia.47.249 　
垂直磁気記録媒体の課題と最近の研究動向

島津武仁

トライボロジスト　52　(6)　400-405　2007年6月
出版者・発行元：（社）トライボロジー学会
パルス磁界VSMによる磁気記録媒体の磁化機構の評価～磁化の熱擾乱の影響を差し引くことで何がわかるのか？～

島津武仁, 青井基

まぐね　2　(1)　20-27　2007年1月
出版者・発行元：（公社）日本磁気学会
ISSN：1880-7208
CoPtCr/(Ru, Pt)薄膜の垂直磁気異方性の熱処理温度依存性

島津武仁, 三塚要, 佐藤英夫, 渡辺功, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　28　496-496　2004年9月21日
Hard/Soft スタック垂直磁気記録媒体の基礎特性

稲葉祐樹, 島津武仁, 北上修, 佐藤英夫, 及川忠昭, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　28　21-21　2004年9月21日
CoPtCr-SiO_2/Ru垂直磁気記録媒体のSiO_2組成と粒子の孤立化

及川忠昭, 島津武仁, 稲葉祐樹, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　28　165-165　2004年9月21日
K_<u2>を利用したCoPtCr-SiO_2垂直磁気記録媒体 : II. K_<u2>媒体の設計と課題

島津武仁, 佐藤英夫, 及川忠昭, 稲葉祐樹, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　28　164-164　2004年9月21日
K_<u2>を利用したCoPtCr-SiO_2垂直磁気記録媒体 : I. 磁気異方性と構造との関係

佐藤英夫, 島津武仁, 三塚要, 北上修, 岡本聡, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　28　163-163　2004年9月21日
28aXR-2 FeCo合金/Pt二層膜におけるPt層中の誘起磁化分布(薄膜,人工格子磁性,微小領域磁性)(領域3)

鈴木基寛, 宮川勇人, 河村直己, 村岡裕明, 島津武仁, 稲葉祐樹, 片田裕之

日本物理学会講演概要集　59　(1)　484-484　2004年3月3日
出版者・発行元：一般社団法人日本物理学会
ISSN：1342-8349
マイクロインダクタ用連続軟磁性体シート

菅原英州, 小野敏明, 白川究, 島津武仁, 増本健, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　188-188　2003年9月1日

ISSN：1340-8100
シリンダ状媒体用ヘッドスライダの再生分解能評価

山田洋, 島津武仁, 渡辺功, 青井基, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　95-95　2003年9月1日

ISSN：1340-8100
K_<u2>効果を利用したCoPtCr-SiO_2/Ru垂直磁気記録媒体の高密度化

島津武仁, 及川忠昭, 北上修, 岡本聡, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　526-526　2003年9月1日

ISSN：1340-8100
CoPtCr-SiO_2/Ru垂直磁気記録媒体のPt, Cr組成と熱安定性

及川忠昭, 島津武仁, 稲葉祐樹, 佐藤英夫, 渡辺功, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　529-529　2003年9月1日

ISSN：1340-8100
CoPtCr-SiO_2/Ru垂直磁気記録媒体のSiO_2組成と高密度化

稲葉祐樹, 島津武仁, 及川忠昭, 佐藤英夫, 渡辺功, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　528-528　2003年9月1日

ISSN：1340-8100
CoPtCr(-SiO_2)/Ru垂直磁気記録媒体用薄膜の高垂直磁気異方性

島津武仁, 佐藤英夫, 及川忠昭, 稲葉祐樹, 北上修, 岡本聡, 村岡裕明, 青井基, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　27　527-527　2003年9月1日

ISSN：1340-8100
31pXF-3 Pt/Co 二層膜の表面 Pt 層に誘起された磁気モーメント

鈴木基寛, 宮川勇人, 河村直己, 村岡裕明, 島津武仁, 稲葉祐樹, 園部義明, 圓山裕, 磯濱陽一, 中村直道, 石松直樹

日本物理学会講演概要集　58　(1)　474-474　2003年3月6日
出版者・発行元：一般社団法人日本物理学会
ISSN：1342-8349
C-7-4 垂直磁気記録媒体の磁気的クラスタサイズと磁化曲線

稲葉祐樹, 島津武仁, 上住洋之, 及川忠昭, 村岡裕明, 中村慶久

電子情報通信学会総合大会講演論文集　2003　(2)　19-19　2003年3月3日
出版者・発行元：一般社団法人電子情報通信学会
垂直磁気記録媒体の磁化曲線の傾きと磁気的クラスタサイズ

島津武仁, 上住洋之, 及川忠昭, 稲葉祐樹, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　140-140　2002年9月1日

ISSN：1340-8100
CoPtCr-SiO_2を用いた垂直磁気記録媒体の微細構造と磁気特性

及川忠昭, 上住洋之, 島津武仁, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　139-139　2002年9月1日

ISSN：1340-8100
高飽和磁化FeCo/NiFe(Cr)膜の構造と軟磁性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　263-263　2002年9月1日

ISSN：1340-8100
シリンダ状磁気ストレージ媒体測定装置の基礎検討

山田洋, 島津武仁, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　265-265　2002年9月1日

ISSN：1340-8100
Co/Pt人工格子垂直磁気記録媒体へのB添加効果

島津武仁, 猪狩孝洋, 寺川潤, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　296-296　2002年9月1日

ISSN：1340-8100
反強磁性的な磁化結合による垂直磁気記録媒体裏打層の単磁区化

島津武仁, 本間一人, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　26　160-160　2002年9月1日

ISSN：1340-8100
SC-6-8 垂直磁気記録媒体の活性化体積と媒体ノイズ

島津武仁, 上住洋之, 村岡裕明, 中村慶久

電子情報通信学会総合大会講演論文集　2002　(2)　160-160　2002年3月7日
出版者・発行元：一般社団法人電子情報通信学会
垂直磁気記録媒体の磁化の熱擾乱と低ノイズ化―パルス磁界を用いた磁留磁化曲線の解析

島津武仁, 上住洋之, 村岡裕明, 中村慶久

日本応用磁気学会誌　26　(3)　109-117　2002年3月
出版者・発行元：（社）日本応用磁気学会
ディスプレイの時間応答と動画の高画質化

片田裕之, 島津武仁, 高橋正晴, 渡辺功, 村岡裕明, 中村慶久

映像情報メディア学会技術報告　26　(1)　17-24　2002年1月17日
出版者・発行元：映像情報メディア学会
ISSN：1342-6893
極薄軟磁性薄膜の誘導磁気異方性と微細構造

片田裕之, 島津武仁, 渡辺博志, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　63-63　2001年9月1日

ISSN：1340-8100
CoTb/CoCrPt系複合型垂直媒体の磁化機構と高密度化

上住洋之, 島津武仁, 酒井泰志, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　16-16　2001年9月1日

ISSN：1340-8100
垂直磁気記録媒体の磁化機構と低ノイズ・高熱安定性

島津武仁, 上住洋之, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　17-17　2001年9月1日

ISSN：1340-8100
CoTb/CoCrPt系複合型垂直媒体の膜厚構成比と記録再生特性

酒井泰志, 上住洋之, 島津武仁, 榎本一雄, 竹野入俊司, 渡辺貞幸, 大久保恵司, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　138-138　2001年9月1日

ISSN：1340-8100
CoCrPt-(Ta,B)垂直記録媒体の初期成長層の低減と磁気特性

上住洋之, 島津武仁, 寺川潤, 酒井泰志, 竹野入俊司, 渡辺貞幸, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　131-131　2001年9月1日

ISSN：1340-8100
CoPrTb/CoCrTa複合型垂直媒体の熱安定性と記録再生特性

島津武仁, 村岡裕明, 里舘慶洋, 村松孝一, 渡辺功, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　134-134　2001年9月1日

ISSN：1340-8100
Co/Pd系人工格子垂直磁化膜の磁気異方性と磁化の熱擾乱

島津武仁, 寺川潤, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　413-413　2001年9月1日

ISSN：1340-8100
NiFe/FeCo/NiFe高飽和磁化薄膜の構造と軟磁気特性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　25　292-292　2001年9月1日

ISSN：1340-8100
Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media (vol 36, pg 2375, 2000)

T Shimatsu, SJ Greaves, K Muramatsu, Watanabe, I, H Muraoka, Y Sugita, Y Nakamura

IEEE TRANSACTIONS ON MAGNETICS　37　(4)　3081-3081　2001年7月
出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
ISSN：0018-9464
Erratum: Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media (IEEE Transactions on Magnetics (Sept. 2000) 36 (2375-2377))

T. Shimatsu, S. J. Greaves, K. Muramatsu, I. Watanabe, H. Muraoka, Y. Sugita, Y. Nakamura

IEEE Transactions on Magnetics　37　3081　2001年7月1日

DOI： 10.1109/TMAG.2001.947073 　

ISSN：0018-9464
CoCr系垂直磁気記録媒体の残留保磁力の角度依存性と磁化の熱擾乱

島津武仁, 上住洋之, 村岡裕明, 中村慶久

電子情報通信学会技術研究報告. MR, 磁気記録　100　(337)　37-42　2000年10月5日
出版者・発行元：一般社団法人電子情報通信学会
ISSN：0913-5685

詳細を見る詳細を閉じる

パルス磁界を用いた磁化率測定装置により, CoCrTa垂直磁気記録媒体の残留保磁力の角度依存性を評価し, 熱擾乱の影響を差し引いた媒体の磁気特性について議論した.その結果, 磁化の熱擾乱の影響を差し引いた残留保磁力H_oの値は, 測定方向と膜面垂直方向とのなす角度φ=45°において緩慢な極小値を示した.また, H_oの角度依存性は, c軸の角度分散を考慮に入れたStoner-Wohlfarth型の一斉磁化反転機構を仮定した計算結果とほぼ一致した.一方, 解析により得られた磁気エネルギーと熱エネルギーの比K_uV/kTの値は, φ=60°において緩慢な極小を示し, K_uV/kTの値が角度φに依存することを実験的に示した.
極薄軟磁性薄膜の誘導 : 軸磁気異方性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　24　95-95　2000年9月1日

ISSN：1340-8100
垂直磁気記録媒体の磁化の熱擾乱と磁気特性

島津武仁, 村松孝一, 吉田亮一, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　24　282-282　2000年9月1日

ISSN：1340-8100
CoCrPt-(Ta,B)垂直磁気記録媒体の磁化の熱擾乱と構造

島津武仁, 上住洋之, 酒井泰志, 大月章弘, 村松孝一, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　24　280-280　2000年9月1日

ISSN：1340-8100
CoCrPt-(Ta,B)垂直磁気記録媒体の構造と記録再生特性

上住洋之, 島津武仁, 酒井泰志, 大月章弘, 吉田亮一, 渡辺功, 村岡裕明, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　24　281-281　2000年9月1日

ISSN：1340-8100
極薄パーマロイ薄膜における誘導磁気異方性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

電子情報通信学会総合大会講演論文集　2000　(2)　21-21　2000年3月7日
出版者・発行元：一般社団法人電子情報通信学会
Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media

T. Shimatsu, S. J. Greaves, K. Muramatsu, I. Watanabe, H. Muraoka, Y. Sugita, Y. Nakamura

Digests of the Intermag Conference　2000年1月1日

ISSN：0074-6843

詳細を見る詳細を閉じる

The value of rotational hysteresis loss (Wr) was measured for various CoCrTa perpendicular media. It was shown that Wr and the hysteresis integral Rh are dependent on the perpendicular anisotropy and the strength of intergranular exchange coupling. Simulated result using a model based on the Landau-Lifshitz-Gilbert (LLG) equation were compared with the experimental results.
CoCrTa/Ti/M垂直二層膜媒体の磁化機構と記録再生特性

島津武仁, 駒込博泰, 村松孝一, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　23　34-34　1999年10月1日
CoCrTa/Ti/M垂直二層膜媒体の記録再生特性の裏打ち層依存性

駒込博泰, 島津武仁, 吉田亮一, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　23　35-35　1999年10月1日
Ta/Ni_<79>Fe_<21>/Ta薄膜における誘導磁気異方性の膜厚依存性

片田裕之, 島津武仁, 渡辺功, 村岡裕明, 中村慶久, 杉田愃

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　23　380-380　1999年10月1日
FePt微結晶薄膜の磁化の熱揺らぎと磁気特性

島津武仁, LODDER J. C., 杉田愃, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　22　350-350　1998年9月1日
垂直二層膜媒体におけるTi中間層の磁気特性に及ぼす影響

パウフィスリスティオ, 駒込博泰, 島津武仁, 渡辺功, 村岡裕明, 杉田愃, 中村慶久

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　22　492-492　1998年9月1日
清浄雰囲気中で作製した薄膜媒体の記録再生特性とその磁化状態 (磁気力顕微鏡による磁化遷移領域の解析)

原寛, 菊池暁, 佐藤博信, 島津武仁, 高橋研

日本応用磁気学会学術講演概要集 = Digest of ... annual conference on magnetics in Japan　20　210-210　1996年9月1日
SOFT MAGNETISM OF SPUTTERED FILMS WITH NANOCRYSTALS

Migaku Takahashi, T.Shimatsu

PROCEEDINGS OF THE 2nd INTERNATIONAL SYMPOSIUM ON PHYSICS OF MAGNETIC MATERIALS 1992(Beiging, China),INTERNATIONAL ACADEMIC PUBLISHERS　78-85　1992年
Magneto-Optical Effect in Fe-Ni, Ni-Co and Fe-Co Binary Alloy Films.

T.Sato, T.Shimatsu, T.Miyahara, T.Miyazaki

Proc. Magn.-Opt. Rec.　113-116　1991年
1a-M1-2 Fe-Si-Alスパッタ薄膜の磁気的不均質性と軟磁性(磁性(薄膜・多層膜・人工格子))

高橋研, 島津武仁, 荘司弘樹, 脇山徳雄

年会講演予稿集　43　(3)　67-67　1988年3月18日
出版者・発行元：一般社団法人日本物理学会

︎全件表示 ︎最初の5件までを表示

書籍等出版物 2

異種材料一体化のための最新技術～溶接・接着剤・一体形成・加飾～

森邦夫, 金子大作, 三浦高行, 竹本正, 安田清和, 須賀唯知, 島津武仁

サイエンス＆テクノロジー株式会社　2012年1月30日

ISBN: 9784864280365
垂直磁気記録の最新技術

中村慶久, 村岡裕明, 沼澤潤二, 島津武仁

シーエムシー出版　2007年7月

講演・口頭発表等 341

Suppression of surface roughening of Ag films by capping layer for Ag/Ag surface activated bonding 国際会議

Yuanhao Cai, Kai Takeuchi, Miyuki Uomoto, Takehito Shimatsu, Eiji Higurashi

12th IEEE CPMT Symposium Japan (ICSJ2023)　2023年11月16日
Blade Test in Atmospheric-Pressure Ar Gas to Characterize Bonded Interface Fabricated Using Atomic Diffusion Bonding 国際会議

H. Iemura, F. Goto, M. Uomoto, T. Shimatsu

244th ECS Meeting　2023年10月11日
Crystal Lattice Rearrangement Occurred at Au/Ag Bonded Interface in Atomic Diffusion Bonding in Vacuum 国際会議

F. Goto, H. Iemura, M. Uomoto, T. Shimatsu

244th ECS Meeting　2023年10月11日

詳細を見る詳細を閉じる

H02-1612
Atomic Diffusion Bonding in Air using Oxide Films 国際会議

T. Shimatsu, M. Uomoto, H. Fukunaga, H. Makita, Y. Suzuki, Y. Kozuka, A. Muraoka, T. Saito

244th ECS Meeting　2023年10月11日

詳細を見る詳細を閉じる

H02-1604
Preferred Grain Orientation to Enhance Interdiffusion at Room Temperature in Atomic Diffusion Bonding: A Fundamental Study using Ni and Cu Films 国際会議

M. Uomoto, S. Kikuchi, F. Goto, T. Shimatsu

244th ECS Meeting　2023年10月11日

詳細を見る詳細を閉じる

H02-1602
マイクロ波アシスト磁化反転時のエネルギー障壁

水谷聡志, 菊池伸明, 畑山正寿, 島津武仁, 岡本聡

第47回日本磁気学会学術講演会　2023年9月28日

詳細を見る詳細を閉じる

28aC-3
マイクロ波アシスト磁化反転と熱揺らぎ

菊池伸明, 佐藤勝成, 水谷聡志, 畑山正寿, 島津武仁, 岡本聡

磁気記録・情報ストレージ研究会（MRIS）　2023年6月9日

詳細を見る詳細を閉じる

(10)/MRIS
Effect of film thickness on microwave assisted switching behavior 国際会議

Nobuaki Kikuchi, Katsunari Sato, Masatoshi Hatayama, Takehito Shimatsu, Satoshi Okamoto

2023年5月16日
ブレード法によるウエハ接合強度の評価に及ぼす測定雰囲気の影響Ⅰ（金属薄膜を用いた原子拡散接合法による接合界面の評価）

家村光, 後藤風輝, 魚本幸, 島津武仁

第 37 回エレクトロニクス実装学会春季講演大会　2023年3月14日

詳細を見る詳細を閉じる

14B1-3
ブレード法によるウエハ接合強度の評価に及ぼす測定雰囲気の影響Ⅱ（ZrO2薄膜を用いた原子拡散接合法による接合界面の評価）

後藤風輝, 家村光, 魚本幸, 島津武仁

第 37 回エレクトロニクス実装学会春季講演大会　2023年3月14日

詳細を見る詳細を閉じる

14B1-2
マイクロ波アシスト磁化反転における熱活性の影響

水谷聡志, 岡本聡

2022年度物質・デバイス領域共同研究拠点展開共同研究研究会　2023年3月14日
Atomic Diffusion Bonding using AlN Films with High Electrical Resistivity 国際会議

A. Muraoka, H. Makita, T. Saitoh, M. Uomoto, T. Shimatsu

WaferBond'22 Conference on Wafer Bonding for Microsystems, 3D- and Wafer Level Integration　2022年10月5日
Atomic Diffusion Bonding of Wafers using Various Oxide Films 国際会議招待有り

T. Shimatsu, M. Uomoto, T. Saito, T. Moriwaki, N. Kato

WaferBond'22 Conference on Wafer Bonding for Microsystems, 3D- and Wafer Level Integration　2022年10月5日
磁性膜厚のマイクロ波アシスト磁化反転挙動への影響

菊池伸明, 佐藤勝成, 畑山正寿, 島津武仁, 岡本聡

第46回日本磁気学会学術講演会　2022年9月8日

詳細を見る詳細を閉じる

08aD-2
マイクロ波アシスト磁化反転における熱活性の影響

水谷聡志, 菊池伸明, 畑山正寿, 島津武仁, 岡本聡

第46回日本磁気学会学術講演会　2022年9月8日

詳細を見る詳細を閉じる

08aD-1
Cuを微量添加したAg薄膜を用いた大気中の原子拡散接合法における接合性能

渡部雄貴, 魚本幸, 島津武仁

第32回マイクロエレクトロニクスシンポジウム MES2022　2022年9月6日

詳細を見る詳細を閉じる

6C2-3
Microwave assisted switching in granular media with continuous capping layers for interaction control 国際会議

Nobuaki Kikuchi, Katsunari Sato, Takehito Shimatsu, Osamu Kitakami, Satoshi Okamoto

Magnetics and Optics Reresearch IInternational Symposium2022(MORIS2022)　2022年5月18日

詳細を見る詳細を閉じる

We-P-04
THERMAL ACTIVATION ON MICROWAVE ASSISTED MAGNETIZATION SWITCHING IN Co/Pt NANODOT ARRAYS 国際会議

Satoshi Mizutani, Nobuaki Kikuchi, Masatoshi Hatayama, Takehito Shimatsu, Satoshi Okamoto

Magnetics and Optics Reresearch IInternational Symposium2022(MORIS2022)　2022年5月17日

詳細を見る詳細を閉じる

Tu-02-3
Co/Ptナノドットを用いたマイクロ波アシスト磁化反転における熱活性の影響

水谷聡志, 菊池伸明, 畑山正寿, 島津武仁, 岡本聡

2021年度物質・デバイス領域共同研究拠点展開共同研究B 研究会　2021年12月28日
Thermal activation on microwave assisted magnetization switching in Co/Pt nanodot arrays 国際会議

S. Mizutani, N. Kikuchi, M. Hatayama, T. Shimatsu, S. Okamoto

The 5th Symposium for core research clusters for materials Science and Spintronics, and the 4th Symposium on International Joint Graduate Program in Materials Science　2021年10月25日
Atomic Diffusion Bonding of Wafers with Oxide Underlayers using Thin Hf Films for Optical Applications 国際会議

G, Yonezawa, M. Uomoto, T. Shimatsu

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月7日

詳細を見る詳細を閉じる

7P-09
Atomic Diffusion Bonding using Y2O3 and ZrO2 films 国際会議

T. Shimatsu, H. Yoshida, M. Uomoto, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, K. Miyamoto

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月7日

詳細を見る詳細を閉じる

7P-08
Atomic Diffusion Bonding using AlN films 国際会議

M. Uomoto, H. Yoshida, T. Shimatsu, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, K. Miyamoto

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月7日

詳細を見る詳細を閉じる

7P-02
Surface Contamination Effects on Bonding Performance in Atomic Diffusion Bonding of Wafers using Amorphous Si Thin Films 国際会議

T, Amino, M. Uomoto, T. Shimatsu

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月7日

詳細を見る詳細を閉じる

7A-02
Preliminary Study of Atomic Diffusion Bonding in Air using Ag films 国際会議

Y. Watabe, F, Goto, M. Uomoto, T. Shimatsu

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月7日

詳細を見る詳細を閉じる

7A-01
Sputtering Technique to Fabricate Smooth Surface Oxide Film for Room Temperature Bonding 国際会議

T. Saito, T. Hanasaki, T. Moriwaki, T. Goto, A. Takeda, A. Miura, M. Uomoto, T. Shimatsu

WaferBond 2021 EAST 2021 7th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2021)　2021年10月5日

詳細を見る詳細を閉じる

5A-05
Co/Pt 多層膜ナノドットのマイクロ波アシスト磁化反転における熱活性

水谷聡志, 菊池伸明, 畑山正寿, 島津武仁, 岡本聡

第45回日本磁気学会学術講演会　2021年8月31日

詳細を見る詳細を閉じる

31pC-6
Co/Pt多層膜ナノドットのマイクロ波アシスト磁化反転における熱活性の影響

水谷聡志, 菊池伸明, 畑山正寿, 岡本聡, 島津武仁

磁気記録・情報ストレージ研究会（MRIS）　2021年6月10日
室温接合技術と接合面の平滑性・清浄度の重要性(原子拡散接合法を例に) 招待有り

島津武仁

公益社団法人精密工学会プラナリゼーションCMPとその応用技術専門委員会第189回研究会　2021年4月26日

詳細を見る詳細を閉じる

基調講演I
マイクロ波アシスト磁化反転における熱揺らぎの影響招待有り

岡本聡, 菊池伸明, 島津武仁

スピントロニクス学術研究基盤と連携ネットワーク拠点年次報告会　2021年3月9日

詳細を見る詳細を閉じる

O-2
Effect of Field Angle on Microwave Assisted Magnetization Switching 国際会議

Nobuaki KIKUCHI, Satoshi OKAMOTO, Takehito SHIMATSU

The 4th International Symposium for The Core Research Cluster for Spintronics　2021年2月24日
Microwave-Assisted Magnetization Switching Behaviors in Granular Media 国際会議招待有り

S. Okamoto, N. Kikuchi, T. Shimatsu

The 31st Magnetic Recording Conference (TMRC 2020)　2020年8月19日
GHz帯の高周波磁場により励起された磁化ダイナミクス

菊池伸明, 岡本聡, 島津武仁

Spin-RNJ 若手オンライン研究発表会　2020年6月4日
Ag薄膜を用いた原子拡散接合法による光学機能性接合界面の形成

村岡有菜, 魚本幸, 島津武仁

第34回エレクトロニクス実装学会春季講演大会　2020年3月3日

詳細を見る詳細を閉じる

3C1-04
薄いTi薄膜を用いた原子拡散接合法における成膜後の真空中保持時間と接合強度

網野泰知郎, 魚本幸, 島津武仁

第34回エレクトロニクス実装学会春季講演大会　2020年3月3日

詳細を見る詳細を閉じる

3C1-03
薄いZr薄膜を用いた原子拡散接合法によるウエハ室温接合

魚本幸, 島津武仁

第34回エレクトロニクス実装学会春季講演大会　2020年3月3日

詳細を見る詳細を閉じる

3C1-02
Atomic Diffusion Bonding of Wafers in Air using Thin Pt Films 国際会議

T. Shimatsu

The International Conference on Wafer Bonding, WaferBond '19　2019年12月2日
原子拡散接合法による室温接合技術と接合面の表面粗さ招待有り

島津武仁

第4回 AFM&CSIソリューションセミナー　2019年11月20日
CoCrPtグラニュラ薄膜における粒子間交換結合のマイクロ波アシスト磁化反転への影響

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

第43回日本磁気学会学術講演会　2019年9月25日

詳細を見る詳細を閉じる

27pC-8
原子拡散接合によるGaN-on-GaN HEMT高放熱特性

岡本直哉, 美濃浦優一, 魚本幸, 島津武仁

第80回応用物理学会秋季学術講演会　2019年9月18日

詳細を見る詳細を閉じる

21p-E301-7
Microwave Assisted Switching on CoPtCr-Based Granular Media 国際会議招待有り

N. Kikuchi, K. Sato, S. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

Magnetics and Optics Research International Symposium(MORIS 2019)　2019年6月23日

詳細を見る詳細を閉じる

Tu-04-1
CoCrPtグラニュラ記録媒体のマイクロ波アシスト磁化反転実験

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

磁気記録・情報ストレージ研究会（MRIS)　2019年6月13日
原子拡散接合ー表面活性化接合の新潮流とその応用招待有り

島津武仁

一般社団法人電子実装工学研究所総会　2019年6月11日
Temporary SiC-SiC wafer bonding compatible with high temperature annealing 国際会議

Fengwen Mu, Tadatomo Suga, Miyuki Uomoto, Takehito Shimatsu

The 69th IEEE Electronic Components and Technology Conference(ECTC 2019)　2019年5月28日
SiC-SiC temporary bonding compatible with rapid thermal annealing at 1000 ℃ 国際会議

Fengwen Mu, Tadatomo Suga, Miyuki Uomoto, Takehito Shimatsu, Kenichi Iguchi, Haruo Nakazawa

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

220-04
Novel Gratings for Astronomical Observations Fabricated by Latest Technologies 国際会議

N. Ebizuka, T. Okamoto, M. Sasaki, I. Tanaka, M. Uomoto, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-34
Rearrangement of Crystal Lattice Occurred at Ag/Ag Bonded Interface in Atomic Diffusion Bonding 国際会議

S. Matsuda, M. Uomoto, A. Miura, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-24
Atomic Diffusion Bonding of Wafers using a-Ge Films with Extremely Low Electrical Conductivity 国際会議

A. Muraoka, M. Uomoto, M. Abe, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-23
Atomic Diffusion Bonding of Wafers Using Thin Nb Films 国際会議

M. Uomoto, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-22
Novel Sputter Film Deposition to Fabricate Thick Films with Extremely Smooth Surface Suitable for Room Temperature Bonding 国際会議

T. Saito, H. Makita, T. Moriwaki, Y. Suzuki, N. Kato, S. Wakayanagi, A. Miura, M. Uomoto, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-21
Oxidation of Bonded Thin Ti Films Using Oxide Underlayers in Atomic Diffusion Bonding Process for Optical Applications 国際会議

G. Yonezawa, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

WaferBond 2019 EAST 2019 6th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2019)　2019年5月21日

詳細を見る詳細を閉じる

22P-20
薄いa-Ge及びa-Si薄膜を用いた原子拡散接合法によるウエハ室温接合

村岡有菜, 魚本幸, 島津武仁

第33回エレクトロニクス実装学会春季講演大会　2019年3月11日
原子拡散接合で作製したInGaAs/a-Ge/InGaAs接合部のバンド構造評価

山田友輝, 魚本幸, 島津武仁, 名田允洋, 中島史人, 松崎秀昭

第66回応用物理学会春季学術講演会　2019年3月9日

詳細を見る詳細を閉じる

11a-M121-10
Atomic Diffusion Bonding: Room Temperature Bonding of Wafers for Creating the Future of Electronic and Optical Devices 国際会議招待有り

Takehito Shimatsu

3D & SYSTEMS SUMMIT　2019年1月28日
原子拡散接合量産装置と接合周辺技術の開発招待有り

森脇崇行, 齋藤孝之, 牧田裕之, 鈴木雄大, 魚本幸, 島津武仁

2018年日本表面真空学会学術講演会　2018年11月19日

詳細を見る詳細を閉じる

3Cp03
Suprious-Free, Near-Zero-TCF Hetero Acoustic Layer (HAL)SAW Resonators Using LiTaO3Thin Plate on Quartz 国際会議

Michio Kadota, Yoshimi Ishii Yunoki, Takehito Shimatsu, Miyuki Uomoto, Shuji Tanaka

2018 IEEE International Ultrasonics Symposium (IUS)　2018年10月25日

詳細を見る詳細を閉じる

6J-2
Atomic Diffusion Bonding for Optical Devices with High Optical Density 国際会議

G. Yonezawa, Y. Takahashi, Y. Sato, S. Abe, M. Uomoto, T. Shimatsu

AiMES 2018 ECS and SMEQ Joint International Meeting　2018年9月30日

詳細を見る詳細を閉じる

G01-0980
Room Temperature Bonding of Wafers Using Si and Ge Films with Extremely Low Electrical Conductivity 国際会議

M. Uomoto, A. Muraoka, T. Shimatsu

AiMES 2018 ECS and SMEQ Joint International Meeting　2018年9月30日

詳細を見る詳細を閉じる

G01-0971
酸化下地膜を用いた原子拡散接合法による高光透過率の接合界面の形成と光学部品への応用

米澤元, 高橋祐一, 佐藤能久, 阿部昇平, 魚本幸, 島津武仁

日本学術振興会産学協力研究委員会接合界面創成技術第191委員会第18回研究会　2018年9月14日
CoCrPt グラニュラ磁気記録媒体におけるマイクロ波アシスト効果の時間依存性

菊地瞬, 島津武仁, 菊池伸明, 岡本聡, 北上修

第42回日本磁気学会学術講演会　2018年9月11日

詳細を見る詳細を閉じる

12pB-4
連続波を用いたCoCrPt グラニュラ記録媒体のマイクロ波アシスト磁化反転実験

佐藤勝成, 菊池伸明, 岡本聡, 北上修, 島津武仁

第42回日本磁気学会学術講演会　2018年9月11日

詳細を見る詳細を閉じる

12pB-3
Microwave assisted switching on CoCrPt based granular media 招待有り

N. Kikuchi, K. Shimada, S. Kikuchi, K. Sato, S. Okamoto, O. Kitakami, T. Shimatsu

第42回日本磁気学会学術講演会　2018年9月11日

詳細を見る詳細を閉じる

11pC-2
積層磁性体ドットにおけるマイクロ波アシスト磁化反転

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

平成30年電気学会基礎・材料・共通部門大会　2018年9月4日

詳細を見る詳細を閉じる

5-E-a1-5
Microwave assisted switching behavior of CoCrPt based granular media 国際会議招待有り

N. Kikuchi, K. Shimada, S. Kikuchi, K. Sato, S. Okamoto, O. Kitakami, T. Shimatsu

The 29th Magnetic Recording Conference (TMRC 2018)　2018年8月18日
Near-Zero TCF of HAL SAW Resonator with LiTaO3-on-Quartz Structure 国際会議

Michio Kadota, Yoshimi Yunoki, Takehito Shimatsu, Miyuki Uomot, Shuji Tanaka

2018 IEEE International Frequency Control Symposium (IFCS)　2018年5月21日
フォトダイオード構造を用いた原子拡散接合InGaAs/Ge/InGaAs界面の電子輸送特性評価

山田友輝, 魚本幸, 島津武仁, 名田允洋, 中島史人, 松崎松崎

第65回応用物理学会春季学術講演会　2018年3月17日

詳細を見る詳細を閉じる

奨18p-C302-13
積層磁性膜におけるマイクロ波アシスト磁化反転招待有り

岡本聡, Lu Yuming, 菊池伸明, 北上修, 島津武仁

平成30年電気学会全国大会　2018年3月14日
CoCrPt-TiO2グラニュラー薄膜におけるマイクロ波アシスト磁化反転挙動

菊池伸明, 島田恭平, 島津武仁, 岡本聡, 北上修

マグネティックス研究会　2018年3月9日

詳細を見る詳細を閉じる

MAG-18-010
High Performance HAL SAW devices with Near-Zero TCF and High Quality 国際会議

Michio Kadota, Yoshimi Yunoki, Takehito Shimatsu, Miyuki Uomoto, Shuji Tanaka

Seventh International Symposium on Acoustic Wave Devices for Future Mobile Communication Systems　2018年3月6日
高性能Hetero Acoustic Layer弾性表面波デバイス

門田道雄, 柚木良美, 島津武仁, 魚本幸, 田中秀治

圧電材料・デバイスシンポジウム2018　2018年2月5日

詳細を見る詳細を閉じる

D-1
Frequency dependence of microwave-assisted switching in CoCrPt granular perpendicular media 国際会議

Kyohei Shimada, Takehito Shimatsu, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami

Magnetics and Optics Research International Symposium(MORIS 2018)　2018年1月7日

詳細を見る詳細を閉じる

Tu-P-01
Elementally resolved ferromagnetic resonance by X-ray magnetic circular dichroism on Co/Pt multilayer dots 国際会議

Nobuaki Kikuchi, Takahiro Yomogita, Daiki Kanahara, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu, Hitoshi Osawa, Yoshinori Kotani, Kentaro Toyoki, Motohiro Suzuki, Tetsuya Nakamura

Magnetics and Optics Research International Symposium(MORIS 2018)　2018年1月7日

詳細を見る詳細を閉じる

Tu-01-03
薄い金属薄膜を用いたウエハの室温接合技術（原子拡散接合法）招待有り

島津武仁

日本学術振興会薄膜第１３１委員会第281回委員会・第287回研究会　2017年12月19日
硬X線MCDによるCo/Ptナノドットの時空間分解強磁性共鳴測定 (Time- and spatially resolved hard X-ray MCD-FMR measurement on a Co/Pt multilayer dot)

菊池伸明, 蓬田貴裕, 金原大樹, 岡本聡, 北上修, 島津武仁, 大沢仁志, 鈴木基寛, N. Kikuchi, T. Yomogita, D. Kanahara, S. Okamoto, O. Kitakami, T. Shimatsu, H. Osawa, M. Suzuki

平成29年度スピニクス研究会　2017年11月28日
Room Temperature Bonding of Wafers using Thin Metal Films for Optical Device Fabrications 国際会議

T. Shimatsu

The International Conference on Wafer Bonding, WaferBond '17　2017年11月27日
双極子結合した積層磁性ドットによるマイクロ波アシスト実験

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

マグネティクス研究会　2017年11月16日
Layer-selective switching in a dot of double AFC layers under the assistance of rf fields 国際会議

Y. Lu, S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu

MMM 2017 – 62nd Annual Conference on Magnetism and Magnetic Materials　2017年11月6日
Time- and spatially resolved hard X-ray MCD with pulsed rf field excitation on a Co/Pt multilayer dot 国際会議

N. Kikuchi, T. Yomogita, D. Kanahara, S. Okamoto, O. Kitakami, T. Shimatsu, H. Osawa, M. Suzuki

MMM 2017 – 62nd Annual Conference on Magnetism and Magnetic Materials　2017年11月6日
Layer-selective switching in a dot of double AFC layers under the assistance of rf fields 国際会議

S. Okamoto, Y. Lu, N. Kikuchi, O. Kitakami, T. Shimatsu

Junjiro Kanamori Memorial International Symposium　2017年9月27日
CoCrPt グラニュラ垂直磁気記録媒体におけるマイクロ波アシスト効果

島田恭平, 島津武仁, 菊池伸明, 岡本聡, 北上修

第41回日本磁気学会学術講演会（平成29年）　2017年9月19日

詳細を見る詳細を閉じる

22pC-1
積層磁性ドットによるマイクロ波アシスト磁化反転

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

第41回日本磁気学会学術講演会（平成29年）　2017年9月19日

詳細を見る詳細を閉じる

22pC-2
高平均出力水の窓軟X線光源のための薄ディスクレーザーの開発

東口武史, 山内駿, 篠崎夏美, 小倉拓人, 藤井雄介, 江島丈雄, 坂上和之, 魚本幸, 島津武仁, MOCEK Tomas

第78回応用物理学会秋季学術講演会　2017年9月5日

詳細を見る詳細を閉じる

5p-S44-7
原子拡散接合GaAsSb/InP-Ti-GaNヘテロ接合バイポーラトランジスタ

星拓也, 山田友輝, 名田允洋, 白鳥悠太, 魚本幸, 島津武仁, 松崎秀昭

第78回応用物理学会秋季学術講演会　2017年9月5日

詳細を見る詳細を閉じる

奨 8a-S22-4
原子拡散接合法による室温接合技術（技術ポテンシャルと応用）招待有り

島津武仁

第3回両国フォトニクスサロン　2017年9月1日
TUNING MAGNETIC ANISOTROPY AND CURIE TEMPERATURE OF L10-FePt GRANULAR FILMS 国際会議招待有り

Takehito SHIMATSU, Takuya ONO, Tomohiro MORIYA, Hitoshi NAKATA, Kazuya KOMIYAMA, Shinji UCHIDA, Hirohisa Oyama, Hiroto KIKUCHI, Hiroyasu KATAOKA, Kiminori SATO, Akira FURUTA, Tsuyoshi YOSHIZAWA, Masatoshi HATAYAMA, Kaoru TSUMURA, Nobuaki KIKUCHI, Osamu KITAKAMI

The 28th Magnetic Recording Conference (TMRC 2017)　2017年8月2日

詳細を見る詳細を閉じる

A1
MAGNETIZATION SWITCHING OF A DOT COMPOSED OF DOUBLE AFC LAYERS UNDER THE ASSISTANCE OF RF FIELDS 国際会議

Yuming LU, Satoshi OKAMOTO, Nobuaki KIKUCHI, Osamu KITAKAMI, Takehito SHIMATSU

The 28th Magnetic Recording Conference (TMRC 2017)　2017年8月2日

詳細を見る詳細を閉じる

DP-19
双極子結合した積層磁性ドットによるマイクロ波アシスト磁化反転

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

磁気記録・情報ストレージ研究会　2017年6月8日
Enhancement of Light Transmittance for Wafers Bonded with Thin Al Films Using Atomic Diffusion Bonding and Subsequent Laser Irradiation 国際会議

M. Ichikawa, N. Eboshi, T. Kemmochi, M. Sano, T. Mukai, M. Uomoto, T. Shimatsu

2017 5th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2017)　2017年5月16日

詳細を見る詳細を閉じる

16GO-06
Shear Strength of Room-Temperature-Bonded Sapphire and Metal Substrates Using Au Films 国際会議

H. Kon, M. Uomoto, N. Nakajima, T. Nakaya, T. Shimatsu

2017 5th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2017)　2017年5月16日

詳細を見る詳細を閉じる

17GP-03
Room Temperature Bonding of InGaAs Wafers Using Thin Ge Films 国際会議

M. Uomoto, Y. Yamada, T Hoshi, M. Nada, T. Shimatsu

2017 5th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2017)　2017年5月16日

詳細を見る詳細を閉じる

17GP-05
Demonstration of laser oscillation of an Yb-doped Y2O3 composite disk by use of atomic diffusion bonding in room temperature 国際会議

T. Higashiguchi, S. Yamauchi, Y. Fujii, N. Shinozaki, T. Ogura, M. Uomoto, T. Shimatsu, T. Miura, Tomáš Mocek

2017 5th International Workshop on Low Temperature Bonding for 3D Integration(LTB-3D 2017)　2017年5月16日

詳細を見る詳細を閉じる

17GP-04
薄いAu薄膜を用いた金属とセラミクスの室温接合と接合性能

魚本幸, 阿部真帆, 島津武仁

第31回エレクトロニクス実装学会春季講演大会　2017年3月6日

詳細を見る詳細を閉じる

8D2-3
Room temperature Bonding using Thin Metal Films (Atomic Diffusion Bonding) 国際会議招待有り

Takehito Shimatsu

2017 IEEE Electron Devices Technology and Manufacturing Conference(EDTM)　2017年2月28日
Transmission gratings and immersion gratings for instruments of Subaru Telescope and TMT 国際会議

Ebizuka, N. Okamoto, T. Takeda, M. Hosobata, T. Yamagata, Y. Sasaki, M. Uomoto, M. Shimatsu, T. Sato, S. Hashimoto, N. Tanaka, I. Hattori, T. Ozaki, S. Aoki

The 9th International Conference on Leading Edge Manufacturing in 21st Century (LEM21)　2017年

詳細を見る詳細を閉じる

C18
積層磁性ドットによるマイクロ波アシスト磁化反転

金原大樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

平成 28 年度スピニクス特別研究会　2016年11月21日
Microwave assisted magnetization switching behaviors in a ferrimagnetic amorphous Gd-Fe-Co single dot 国際会議

Y. Lu, S. Okamoto, N. Kikuchi, B. Lao, Y. Kusanagi, O. Kitakami, T. Shimatsu

61st Annual Conference on Magnetism and Magnetic Materials　2016年10月31日

詳細を見る詳細を閉じる

HH-13
Ru addition into L10-FePt thin film to lower Tc for heat-assisted magnetic recording 国際会議

T. Ono, H. Nakata, T. Moriya, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

61st Annual Conference on Magnetism and Magnetic Materials　2016年10月31日

詳細を見る詳細を閉じる

HH-04
Time resolved FMR measurement in non-linear regime on a Co/Pt multilayer dot measured by XMCD 国際会議

N. kikuchi, T. Yomogita, D. Kanahara, S. Okamoto, O. Kitakaim, T. Shimatsu, H. Osawa, M. Suzuki

61st Annual Conference on Magnetism and Magnetic Materials　2016年10月31日

詳細を見る詳細を閉じる

AB-06
Microwave-Assisted Magnetization Switching in Granular Media 国際会議招待有り

S. Okamoto, N. Kikuchi, B. Lao, Y. Kusanagi, Y. Lu, O. Kitakami, Y. Nakayama, A. Hotta, T. Shimatsu

Advanced Storage Technology Consortium Fall 2016 Research Review Meeting　2016年10月12日
Room Temperature Boding of Solid Substrates using Thin Metal Films(Atomic Diffusion Bonding) 国際会議招待有り

Takehito Shimatsu, Miyuki Uomoto

10th International Conference on Trends in Welding Research & 9th International Welding Symposium of Japan Welding Society (9WS)　2016年10月11日

詳細を見る詳細を閉じる

S4-1
High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room-Temperature Bonding 国際会議招待有り

M. Ichikawa, S. Endo, H. Sagawa, A. Fujioka, T. Kosugi, T. Mukai, M. Uomoto, T. Shimatsu

PRiME 2016/230th ECS Meeting　2016年10月2日

詳細を見る詳細を閉じる

2072
Necessary Thickness of Au Capping Layers for Room Temperature Bonding of Wafers in Air Using Thin Metal Films with Au Capping Layers 国際会議

Miyuki Uomoto, Takehito Shimatsu

PRiME 2016/230th ECS Meeting　2016年10月2日

詳細を見る詳細を閉じる

2073
Room temperature Bonding using Thin Metal Films: Technical Potential and Current Status 国際会議招待有り

Takehito Shimatsu

2016 International Conference on Solid State Devices and Materials　2016年9月26日

詳細を見る詳細を閉じる

M-5-01
薄いAu薄膜を用いたアルミ合金とステンレス合金の大気中の室温接合

魚本幸, 阿部真帆, 島津武仁

第26回マイクロエレクトロニクスシンポジウム秋季大会 MES2016　2016年9月8日

詳細を見る詳細を閉じる

2D2-1
薄いAu薄膜を用いたアルミ合金とCuの大気中の室温接合

阿部真帆, 魚本幸, 島津武仁

第26回マイクロエレクトロニクスシンポジウム秋季大会 MES2016　2016年9月8日

詳細を見る詳細を閉じる

2D2-2
硬X線MCDによるCo/Ptドットの磁化ダイナミクスの時間分解測定

菊池伸明, 蓬田貴裕, 金原大樹, 岡本聡, 北上修, 島津武仁, 大沢仁志, 鈴木基寛

第40回日本磁気学会学術講演会（平成28年）　2016年9月5日

詳細を見る詳細を閉じる

06aE-1
Microwave assisted switching and its application to 3D recording system 国際会議招待有り

N. Kikuchi, S. Okamoto, H. Suto, Y. Nakayama, O. Kitakami, K. Kudo, T. Nagasawa, T. Katnao, K. Mizushima, R. Sato, T. Shimatsu

The 4th International Conference of Asian Union of Magnetic Societies　2016年8月1日

詳細を見る詳細を閉じる

AC-01
Novel diffraction gratings for next generation spectrographs with high spectral dispersion 国際会議

N. Ebizuka, T. Okamoto, T. Hosobata, Y. Yamagata, M. Sasaki, M. Uomoto, T. Shimatsu, S. Sato, N. Hashimoto, I. Tanaka, T. Hattori, S. Ozaki, W. Aoki

SPIE Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II　2016年6月26日

詳細を見る詳細を閉じる

9912-104
薄いAu薄膜を用いた金属バルク材の室温接合と接合性能

魚本幸, 島津武仁

第30回エレクトロニクス実装学会春季講演大会　2016年3月22日

詳細を見る詳細を閉じる

22B1-1
原子拡散接合で作製されたPIN-ダイオードの電気特性

山田友輝, 魚本幸, 島津武仁, 名田允洋, 松崎秀昭

第63回応用物理学会春季学術講演会　2016年3月19日

詳細を見る詳細を閉じる

22p-W541-1
常温直接接合を用いた深紫外LEDの開発

市川将嗣, 遠藤慎哉, 佐川治信, 向井孝志, 魚本幸, 島津武仁

日本学術振興会産学協力研究委員会接合界面創成技術第191委員会第３回委員会・研究会　2016年2月17日
原子拡散接合法によるウエハの室温接合技術とデバイス形成への応用招待有り

島津武仁, 魚本幸

応用物理学会薄膜・表面物理分科会「第21回電子デバイス界面テクノロジー研究会」　2016年1月22日
Experimental investigation of off-stoichiometry and 3d-metal (Mn, Ni, Cu)-substitution in epitaxial FePt thin films. 国際会議

T. Ono, H. Nakata, T. Moriya, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

13th Joint MMM/Intermag Conference 2016　2016年1月11日

詳細を見る詳細を閉じる

AH-11
Microwave assistance effect on magnetization switching in antiferromagnetically coupled CoCrPt granular media. 国際会議

Y. Nakayama, Y. Kusanagi, T. Shimatsu, N. Kikuchi, S. Okamoto, O. Kitakami

13th Joint MMM/Intermag Conference 2016　2016年1月11日

詳細を見る詳細を閉じる

CV-10
Detection of ferromagnetic resonance on Pt layers of a Co/Pt multilayer single dot by micro-XMCD magnetometry. 国際会議

N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu, M. Suzuki

13th Joint MMM/Intermag Conference 2016　2016年1月11日

詳細を見る詳細を閉じる

EB-03
Magnetic anisotropy and crystal domain variant in L10-FePt poly-crystalline films. 国際会議

A. Hotta, T. Ono, T. Shimatsu, N. Kikuchi, S. Okamoto, O. Kitakami

13th Joint MMM/Intermag Conference 2016　2016年1月11日

詳細を見る詳細を閉じる

FV-05
Granular nanostructures and magnetic characteristics of FePt-GeO2/FePt-C stacked granular films. 国際会議

T. Ono, T. Moriya, M. Hatayama, K. Tsumura, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

13th Joint MMM/Intermag Conference 2016　2016年1月11日

詳細を見る詳細を閉じる

CV-08
Room Temperature Bonding of Wafers in Air using Ag, Al, Cu Films with Thin Au Capping Layers. 国際会議

T. Shimatsu

Conference on Wafer Bonding for Microsystems 3D- and Wafer Level Integration (Waferbond'15)　2015年12月7日
Atomic Diffusion Bnding and its practical applications 国際会議招待有り

T. Shimatsu

International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT2015)　2015年10月21日
薄いAuキャップ付きAg, Cu, Al薄膜を用いたウエハの大気中室温接合

魚本幸, 島津武仁

(一社)スマートプロセス学会第11 回電⼦デバイス実装研究委員会　2015年9月15日
L10-FePt多結晶膜における磁気異方性とバリアント形成のFe組成依存性

堀田明良, 小野拓也, 島津武仁, 菊池伸明, 岡本聡, 北上修

第39回日本磁気学会学術講演会（平成27年）　2015年9月8日

詳細を見る詳細を閉じる

08pC-3
マイクロ波磁場により励起されたCo/Pt 多層膜ドットのナノビームX線磁気円二色性測定

菊池伸明, 岡本聡, 北上修, 島津武仁, 鈴木基寛

第39回日本磁気学会学術講演会（平成27年）　2015年9月8日

詳細を見る詳細を閉じる

09aC-6
マイクロ波アシスト磁化反転と強磁性共鳴の同一Co/Pt ナノドット試料での測定

草薙勇作, 岡本聡, 菊池伸明, 北上修, 島津武仁

第39回日本磁気学会学術講演会（平成27年）　2015年9月8日

詳細を見る詳細を閉じる

09aC-7
反強磁性結合を有するマイクロ波アシスト記録用CoCrPt グラニュラ垂直記録媒体の磁化反転機構

中山湧稀, 草薙勇作, 島津武仁, 菊池伸明, 岡本聡, 北上修

第39回日本磁気学会学術講演会（平成27年）　2015年9月8日

詳細を見る詳細を閉じる

11aD-5
次世代天文学観察用の新しい回折格子2

海老塚昇, 岡本隆之, 山形豊, 森田晋也, 佐々木実, 魚本幸, 島津武仁, 田辺綾乃, 橋本信幸, 桐野宙治, 尾崎忍夫, 青木和光, 高見英樹

2015年度精密工学会秋季大会学術講演会　2015年9月4日

詳細を見る詳細を閉じる

D01
薄いAu 薄膜を用いたFe バルク材の室温接合と接合性能

魚本幸, 島津武仁

第25回マイクロエレクトロニクスシンポジウム秋季大会 MES2015　2015年9月3日

詳細を見る詳細を閉じる

2D1
次世代天文学観測装置用の新しい高分散回折格子

海老塚昇, 岡本隆之, 森田晋也, 山形豊, 佐々木実, 魚本幸, 島津武仁, 田辺綾乃, 橋本信幸, 桐野宙治, 尾崎忍夫, 青木和光, 高見英樹

第40回日本光学会光学シンポジウム　2015年6月25日
A theoretical study of thermally activated magnetization switching under microwave assistance. 国際会議

H. Suto, K. Kudo, T. Nagasawa, T. Kanao, K. Mizushima, R. Sato, S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu

2015 IEEE International Magnetics Conference　2015年5月11日
ナノ金属薄膜を用いたポリマーシートの大気中の室温接合

魚本幸, 今一恵, 島津武仁

第29回エレクトロニクス実装学会春季講演大会　2015年3月16日
Auキャップ付金属薄膜を用いたウエハの大気中室温接合Ⅱ（Cu, Al薄膜）

魚本幸, 今一恵, 島津武仁

第29回エレクトロニクス実装学会春季講演大会　2015年3月16日
Au-(Ag, Cu)合金薄膜を用いたウエハの大気中室温接合と接合性能

今一恵, 魚本幸, 島津武仁

第29回エレクトロニクス実装学会春季講演大会　2015年3月16日
Auキャップ付金属薄膜を用いたウエハの大気中室温接合Ⅰ（Ag薄膜）

今一恵, 魚本幸, 島津武仁

第29回エレクトロニクス実装学会春季講演大会　2015年3月16日
Au薄膜を用いた大気中室温接合技術による超高真空用サファイアビューポートの形成

石井美帆, 今一恵, 魚本幸, 中谷隆之, 島津武仁

第29回エレクトロニクス実装学会春季講演大会　2015年3月16日
深紫外LEDの高出力化

市川将嗣, 藤岡陽, 小杉卓生, 遠藤慎哉, 佐川治信, 玉置寛人, 向井孝志

第62回応用物理学会春季学術講演会　2015年3月11日
Microwave assisted magnetization switching based on non-uniform precession mode in layered nanodot 国際会議

Masaki Furuta, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

59th Annual Conference on Magnetism and Magnetic Materials, MMM 2014　2014年11月3日

詳細を見る詳細を閉じる

BP-14
Magnetic characteristics and grain structures of FePt-(B, C)/FePt-C stacked granular films 国際会議

Akira Furuta, Hiroto Kikuchi, Hiroyasu Kataoka, Takuya Ono, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

59th Annual Conference on Magnetism and Magnetic Materials, MMM 2014　2014年11月3日

詳細を見る詳細を閉じる

FQ-10
Quantized spin wave modes on nanosized Co/Pt multilayer dots 国際会議

Nobuaki Kikuchi, Masaki Furuta, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

59th Annual Conference on Magnetism and Magnetic Materials, MMM 2014　2014年11月3日

詳細を見る詳細を閉じる

GD-06
Room Temperature Bonding Using Thin Metal Films (Bonding Energy and Technical Potential) 国際会議招待有り

T. Shimatsu, M. Uomoto, H. Kon

the 226th ElectroChemical Society (ECS) Meeting　2014年10月5日

詳細を見る詳細を閉じる

1754, 8 October 2014
Switching Behaviors of Co/Pt Nanodots and Its Dynamics under the Assistance of Rf Field 国際会議招待有り

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami (IMRAM, Tohoku University, d T. Shimatsu (FRIS, Tohoku University, RIEC, Tohoku Universi

the 226th ElectroChemical Society (ECS) Meeting　2014年10月5日

詳細を見る詳細を閉じる

900, 6 October 2014
積層磁性ドットにおけるマイクロ波アシスト磁化反転

古田正樹, 岡本聡, 菊地伸明, 北上修, 島津武仁

第38回日本磁気学会学術講演会（平成26年）　2014年9月2日

詳細を見る詳細を閉じる

3aA-4
Co/Pt ナノドットの強磁性共鳴測定

菊池伸明, 古田正樹, 岡本聡, 北上修, 島津武仁

第38回日本磁気学会学術講演会（平成26年）　2014年9月2日

詳細を見る詳細を閉じる

3aE-8
結晶粒内で反強磁性的結合を有するCoCrPt グラニュラ垂直磁気記録媒体の磁気特性と磁化反転機構

中山湧稀, 堀田明良, 島津武仁, 菊池伸明, 岡本聡, 北上修

第38回日本磁気学会学術講演会（平成26年）　2014年9月2日

詳細を見る詳細を閉じる

3pE-2
L10-FePt多結晶垂直磁化膜のPt 表面偏析と規則度のPt 組成依存性

堀田明良, 小野拓也, 島津武仁, 菊池伸明, 岡本聡, 北上修

第38回日本磁気学会学術講演会（平成26年）　2014年9月2日

詳細を見る詳細を閉じる

3pE-3
Co/Pt ナノドットにおけるマイクロ波アシスト磁化反転挙動のサイズ依存性

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

電気学会Ａ部門大会　2014年8月21日
Co/Ptナノドットのマイクロ波磁化反転招待有り

菊池伸明, 古田正樹, 岡本聡, 北上修, 島津武仁

MSJスピンエレクトロニクス専門研究会　2014年7月30日
Room Temperature Bonding of Wafers in Air using Au-Ag Alloy Films 国際会議

H. Kon, M. Uomoto, T. Shimatsu

2014 4th International IEEE Workshop on Low Temperature Bonding for 3D Integration, LTB3D 2014　2014年7月15日
Room Temperature Bonding of Sapphire with Sapphire or Metal Substrates in Air using Au Films 国際会議

M. Ishii, H. Kon, M. Uomoto, T. Nakaya, T. Shimatsu

2014 4th International IEEE Workshop on Low Temperature Bonding for 3D Integration, LTB3D 2014　2014年7月15日
原子拡散接合法による室温接合技術招待有り

島津武仁, 魚本幸, 今一恵

溶接学会第107回マイクロ接合研究委員会　2014年7月4日

詳細を見る詳細を閉じる

マイクロ接合優秀研究賞受賞記念講演
Switching dynamics of Co/Pt nanodots under the assistance of rf field 国際会議招待有り

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami, T. Shimatsu

MISM 2014　2014年6月29日
マイクロ波アシスト磁化反転技術の現状と課題招待有り

岡本聡, 古田正樹, 菊池伸明, 北上修, 島津武仁

第21回みちのく磁性談話会　2014年6月7日
Ferromagnetic resonance measurements on single nanoscale Co/Pt dots with perpendicular anisotropy 国際会議

N. Kikuchi, S. Okamoto, M. Furuta, O. Kitakami, T. Shimatsu

the IEEE International Magnetics Conference, INTERMAG Europe 2014　2014年5月4日
Ag薄膜を用いたウエハの室温接合と接合性能

今一恵, 魚本幸, 島津武仁

第28回エレクトロニクス実装学会春季講演大会　2014年3月5日

詳細を見る詳細を閉じる

7C-08
W薄膜を用いたウエハの室温接合技術におけるW膜厚と接合性能

魚本幸, 今一恵, 島津武仁

第28回エレクトロニクス実装学会春季講演大会　2014年3月5日

詳細を見る詳細を閉じる

7C-07
原子拡散接合法を用いた室温接合技術 Room Temperature Bonding using Thin Metal Films (Atomic Diffusion Bonding) 招待有り

島津武仁, 魚本幸, 今一恵

第20回「エレクトロニクスにおけるマイクロ接合・実装技術」シンポジウム，Mate 2014　2014年2月4日

詳細を見る詳細を閉じる

[A-2] 低温実装プログラムNo.6（企画） Feb. 2nd
スピントルク発振による磁気共鳴を用いた3次元磁気記録招待有り

日本磁気学会第194回研究会　2014年1月10日

詳細を見る詳細を閉じる

佐藤利江，首藤浩文，工藤究，永澤鶴美，水島公一，久保田均，今村裕志，谷口友大，田丸慎吾，荒井礼子，松本利映，福島章雄，鈴木義茂,，前原大樹，江村藍，恒川孝二，岡本聡，菊池伸明，島津武仁，北上修
Room Temperature Bonding of Wafers and Polished Metals using Thin Au Films for Enhancing the Heat Dissipation Efficiency 国際会議

H. Kon, M. Uomoto, T. Shimatsu

The International Conference on Wafer Bonding, WaferBond '13　2013年12月5日

詳細を見る詳細を閉じる

Dec. 5th, P18
Room Temperature Bonding of Wafers using Thin Metal Films with High Electrical Resistivities 国際会議

T. Shimatsu, M. Uomoto, H. Kon

The International Conference on Wafer Bonding, WaferBond '13　2013年12月5日

詳細を見る詳細を閉じる

Dec. 6th
Rise time effect on magnetization reversal of Co/Pt multilayer nanodots by nanoseconds pulse fields 国際会議招待有り

N. Kikuchi, S. Okamoto, M. Furuta, O. Kitakami, T. Shimatsu

Magnetics and Optics Research International Symposium, MORIS 2013　2013年12月2日

詳細を見る詳細を閉じる

Tu-03-01
Curie temperature and magnetic anisotropy for L10 type Fe-Pt-Cu single crystal films 国際会議

Tomohiro Moriya, Hitoshi Nakata, Kazuya Komiyama, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

BT-05
Switching field and critical frequency distributions on microwave assisted switching in Co/Pt nanodot array 国際会議

Masaki Furuta, Satoshi Okamoto, Nobuaki Kikuchi, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

BT-14
Switching field reduction of Co-Cr-Pt granular film under the assistance of rf fields 国際会議

Satoshi Okamoto, Nobuaki Kikuchi, Akira Hotta, Masaki Furuta, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

CT-14
Grain segregation and uniaxial magnetic anisotropy for L10 type FePt-X (X=SiC, TiC) films on FePt-C template 国際会議

Hiroyasu Kataoka, Hiroto Kikuchi, Akira Furuta, Kaoru Tsumura, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

DT-14
Magnetic anisotropy and order structure of (001) textured L10-FePt polycrystalline films deposited on MgO seed layers 国際会議

Akira Hotta, Takuya Ono, Masatoshi Hatayama, Kaoru Tsumura, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

DT-15
Granular nanostructure and magnetic characteristics of FePt-MOx/FePt-C (M = Ti, Si) stacked granular films 国際会議

Takuya Ono, Tomohiro Moriya, Masatoshi Hatayama, Nobuaki Kikuchi, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

FE-06
Time dependent coercivity of granular media in a time scale from nanosecond to sub-millisecond regime 国際会議

Nobuaki Kikuchi, Akira Hotta, Kazuya Kadonosawa, Masaki Furuta, Satoshi Okamoto, Osamu Kitakami, Takehito Shimatsu

58th Annual Conference on Magnetism and Magnetic Materials, MMM 2013　2013年11月4日

詳細を見る詳細を閉じる

HF-04
放熱用金属バルク材と電子デバイス用ウエハの大気中低温接合技術の開発

今一恵, 魚本幸, 島津武仁

第23回マイクロエレクトロニクスシンポジウム MES2013　2013年9月12日

詳細を見る詳細を閉じる

2A3-2
a-Si，a-Ge薄膜を用いたウエハの室温接合と接合性能

魚本幸, 今一恵, 島津武仁

第23回マイクロエレクトロニクスシンポジウム MES2013　2013年9月12日

詳細を見る詳細を閉じる

2D1-2
L10-FePt垂直磁化膜の一軸磁気異方性の膜厚依存性

堀田明良, 小野拓也, 島津武仁, 菊池伸明, 岡本聡, 北上修

第37回日本磁気学会学術講演会（平成25年）　2013年9月3日

詳細を見る詳細を閉じる

4pD-1
マイクロ波アシスト磁化反転におけるCo/Ptドット依存性

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

第37回日本磁気学会学術講演会（平成25年）　2013年9月3日

詳細を見る詳細を閉じる

5pA-5
Co/Ptナノドットのマイクロ波アシストにおける反転磁場分散と臨界周波数分散

古田正樹, 岡本聡, 菊池伸明, 北上修, 島津武仁

第37回日本磁気学会学術講演会（平成25年）　2013年9月3日

詳細を見る詳細を閉じる

5pA-6
Au薄膜を用いた大気中のウエハ室温接合における大気暴露時間と接合性能

今一恵, 魚本幸, 島津武仁

第27回エレクトロニクス実装学会春季講演大会　2013年3月13日

詳細を見る詳細を閉じる

15A-09
Ti薄膜を用いたウエハの室温接合技術におけるTi膜厚と接合性能

魚本幸, 今一恵, 島津武仁

第27回エレクトロニクス実装学会春季講演大会　2013年3月13日

詳細を見る詳細を閉じる

15A-10
Switching behaviors and its dynamics in a single Co/Pt multi- layer nanodot under microwave assistance 国際会議

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami, T. Shimatsu

12th Joint MMM/Intermag Conference 2013　2013年1月14日

詳細を見る詳細を閉じる

CB-02
Microwave assisted switching experiments in Co/Pt dot array with narrow switching field distribution 国際会議

M. Furuta, S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu

12th Joint MMM/Intermag Conference 2013　2013年1月14日

詳細を見る詳細を閉じる

CB-10
Irreversible magnetization reversal by in-plane pulse field in perpendicularly magnetized nanodots 国際会議

N. Kikuchi, Y. Suyama, M. Furuta, S. Okamoto, O. Kitakami, T. Shimatsu

12th Joint MMM/Intermag Conference 2013　2013年1月14日

詳細を見る詳細を閉じる

CP-03
Investigation of Surface Activation Bonding for Elucidation of Deposition Mechanism of Cold Spraying 国際会議

Kentaro HASHIMOTO, Kazuhiro OGAWA, Takehito SHIMATSU

The 5th Asian Thermal Spray Conference, ATSC2012　2012年11月26日

詳細を見る詳細を閉じる

S-6
Switching behavior of single Co/Pt nanodot under microwave assistance

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami, T. Shimatsu

平成24年度スピニクス特別研究会　2012年11月26日

詳細を見る詳細を閉じる

12-6-13
Microwave assisted switching experiment on Co/Pt multilayer dot array 国際会議

M. Furuta, N. Kikuchi, S. Okamoto, O. Kitakami, T. Shimatsu

International Conference of the Asian Union of Magnetics Societies, ICAUMS 2012　2012年10月2日

詳細を見る詳細を閉じる

2pA-7
Switching behavior of single Co/Pt nanodot under microwave assistance 国際会議

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami, T. Shimatsu

International Conference of the Asian Union of Magnetics Societies, ICAUMS 2012　2012年10月2日

詳細を見る詳細を閉じる

2pA-8
Magnetization reversal experiments on Co/Pt multilayer dot with a pulse field perpendicular to the magnetization 国際会議

N. Kikuchi, Y. Suyama, S. Aizawa, S. Okamoto, O. Kitakami, T. Shimatsu

International Conference of the Asian Union of Magnetics Societies, ICAUMS 2012　2012年10月2日

詳細を見る詳細を閉じる

3pA-2
Microwave Assisted Magnetization Switching In Co/Pt Nanodot 国際会議招待有り

S. Okamoto, N. Kikuchi, M. Furuta, O. Kitakami, T. Shimatsu, Hajime Aoi

23rd Magnetic Recording Conference, TMRC 2012　2012年8月20日

詳細を見る詳細を閉じる

B6
Atomic Diffusion Bonding of Wafers in Air with Thin Au Films and Its Application to Optical Devices Fabrication 国際会議

T. Shimatsu, M. Uomoto, K. Oba, Y. Furukata

2012 3rd International IEEE Workshop on Low Temperature Bonding for 3D Integration, LTB3D 2012　2012年5月22日

詳細を見る詳細を閉じる

May 22
Atomic Diffusion Bonding with Thin Nanocrystalline Metal Films in Vacuum and in an Inert Gas 国際会議

T. Shimatsu, M. Uomoto

2012 3rd International IEEE Workshop on Low Temperature Bonding for 3D Integration, LTB3D 2012　2012年5月22日

詳細を見る詳細を閉じる

May 23
Write margin measurement of bit patterned media with 20 nm dots 国際会議

H. Saga, K. Shirahata, R. Terashima, T. Shimatsu, H. Aoi, H. Muraoka

IEEE International Magnetics Conference, Intermag 2012　2012年5月7日

詳細を見る詳細を閉じる

EU-03
Room Temperature Bonding of Wafers in an Inert Gas with Thin Nanocrystalline Metal Films 国際会議

T. Shimatsu

The International Conference on Wafer Bonding, WaferBond '11　2011年12月6日

詳細を見る詳細を閉じる

Dec. 7
Magnetic anisotropy and order parameters for L10 type FePt polycrystalline films with (001) preferred grain orientation 国際会議

D. Inoue, T. Shimatsu, Y. Inaba, H. Aoi, S. Okamoto, O. Kitakami

56th Annual Conference on Magnetism and Magnetic Materials, MMM 2011　2011年10月30日

詳細を見る詳細を閉じる

DD-04
Switching behavior of Co/Pt multilayer nanodots under microwave assistance 国際会議

S. Okamoto, N. Kikuchi, J. Li, O. Kitakami, T. Shimatsu, H. Aoi

56th Annual Conference on Magnetism and Magnetic Materials, MMM 2011　2011年10月30日

詳細を見る詳細を閉じる

FG-09
Magnetic anisotropy of L10 type FePt-X (X=C, SiO2 and TiO2) granular media 国際会議

Y. Inaba, T. Shimatsu, D. Inoue, K. Kudo, H. Aoi, S. Okamoto, O. Kitakami

56th Annual Conference on Magnetism and Magnetic Materials, MMM 2011　2011年10月30日

詳細を見る詳細を閉じる

GU-07
Grain segregation and thermal stability for thin L10-FePt-C granular media 国際会議

K. Kudo, Y. Inaba, D. Inoue, H. Aoi, T. Shimatsu

56th Annual Conference on Magnetism and Magnetic Materials, MMM 2011　2011年10月30日

詳細を見る詳細を閉じる

GU-09
Dry-etching damage to magnetic anisotropy of Co-Pt dot arrays characterized using anomalous Hall effect 国際会議

T. Shimatsu, H. Kataoka, K. Mitsuzuka, H. Aoi, N. Kikuchi, O. Kitakami

56th Annual Conference on Magnetism and Magnetic Materials, MMM 2011　2011年10月30日

詳細を見る詳細を閉じる

HQ-02
Co/Pt 多層膜ナノドットにおけるマイクロ波アシスト磁化反転実験

岡本聡, Jin LI, 菊池伸明, 北上修, 島津武仁, 青井基

第35回日本磁気学会学術講演会（平成23年）　2011年9月27日

詳細を見る詳細を閉じる

28aA-9
Co/Pt 多層膜の強磁性共鳴と緩和定数評価

李瑨, 菊池伸明, 岡本聡, 北上修, 島津武仁, 青井基, 加藤剛志, 岩田聡

第35回日本磁気学会学術講演会（平成23年）　2011年9月27日

詳細を見る詳細を閉じる

29pF-2
Analysis of Write Margin Loss Factors in Bit Patterned Media Recording 国際会議

H. Saga, K. Shirahata, K. Mitsuzuka, T. Shimatsu, H. Aoi, H. Muraoka

International Magnetics Conference, Intermag 2011　2011年4月25日

詳細を見る詳細を閉じる

AU-01
L10-FePt-C granular media fabricated by low temperature sputter film deposition 国際会議

Y. Inaba, T. Shimatsu, D. Inoue, H. Nakata, K. Komiyama, H. Aoi, O. Kitakami, S. Okamoto

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

AF-13
Experimental Write Margin Analysis of Bit Patterned Media 国際会議

H. Aoi, H. Saga, K. Shirahata, K. Miura, T. Shimatsu, H. Muraoka

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

AR-06
Magnetic properties of L11-type CoPt-X (X: C, SiO2, MgO) ordered alloy perpendicular films 国際会議

H. Kataoka, T. Shimatsu, Y. Inaba, S. Okamoto, O. Kitakami, H. Aoi

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

BW-10
Coercivity at a recording speed of CoPtCr-SiO2 based granular media for thermally assisted recording 国際会議

D. Inoue, Y. Inaba, K. Komiyama, T. Shimatsu

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

BW-12
Magnetostriction of Co-Fe-Zr-Ta amorphous thin films for soft underlayers of recording media 国際会議

H. Nakata, K. Komiyama, T. Shimatsu

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

BW-11
Microwave assisted magnetization switching in Co/Pt multilayer 国際会議

S. Okamoto, N. Kikuchi, O. Kitakami, T. Shimatsu, H. Aoi

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

DF-11
Nucleation size for dot arrays of Co-Pt based perpendicular films characterized by time dependence of coercivity 国際会議

H. Kataoka, T. Shimatsu, K. Mitsuzuka, H. Aoi, N. Kikuchi, O. Kitakami

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

GU-06
Dot arrays of L10 type FePt ordered alloy perpendicular films fabricated by low-temperature sputter film deposition 国際会議

T. Shimatsu, Y. Inaba, H. Kataoka, J. Sayama, H. Aoi, O. Kitakami, S. Okamoto

55th Annual Conference on Magnetism and Magnetic Materials, MMM 2010　2010年11月14日

詳細を見る詳細を閉じる

HH-09
Room Temperature Bonding of Wafers with Thin Nanocrystalline Metal Films 国際会議招待有り

T. Shimatsu, M. Uomoto

the 218th ElectroChemical Society (ECS) Meeting　2010年10月10日
Magnetic Anisotropy of L11-type Co-Pt-M(M:Ni, Fe, Cr, Mn, Pd)Ordered Alloy Perpendicular Films 国際会議

Hiroyasu Kataoka, Takehito Shimatsu, Satoshi Okamoto, Osamu Kitakami, Hajime Aoi

The 2nd International Symposium on Advanced Magnetic Materials and Applications, ISAMMA 2010　2010年7月12日

詳細を見る詳細を閉じる

SF-05
Nucleation Size of hcp-CoPt Nano-Dot Arrays 国際会議

Takehito Shimatsu, Kaname Mitsuzuka, Nobuaki Kikuchi, Osamu Kitakami, Hajime Aoi

The 2nd International Symposium on Advanced Magnetic Materials and Applications, ISAMMA 2010　2010年7月12日

詳細を見る詳細を閉じる

SG-05
Basic Read/Write Characteristics Measurements of BPM with Static Tester 国際会議

Hajime Aoi, Hideki Saga, Ryosuke Tatsuno, Kazuki Shirahata, Kaname Mitsuzuka, Kenji Miura, Takehito Shimatsu, Hiroaki Muraoka

The 9th Perpendicular Magnetic Recording Conference, PMRC 2010　2010年5月17日

詳細を見る詳細を閉じる

18aA-5
Nucleation Size of hcp-CoPt Dot Arrays 国際会議

Takehito Shimatsu, Kaname Mitsuzuka, Nobuaki Kikuchi, Osamu Kitakami, Hajime Aoi

The 9th Perpendicular Magnetic Recording Conference, PMRC 2010　2010年5月17日

詳細を見る詳細を閉じる

18aD-20
Equilibrium Domain State of Circular Nanomagnet 国際会議

O. Kitakami, S. Okamoto, N. Kikuchi, T. Shimatsu, K. Mituzuka, H. Aoi

The 9th Perpendicular Magnetic Recording Conference, PMRC 2010　2010年5月17日

詳細を見る詳細を閉じる

18aD-21
Magnetic Anisotropy of L11-type Co-Pt-M (M: Ni, Fe, Cr, Mn, Pd) Ordered Alloy Perpendicular Films 国際会議招待有り

Takehito Shimatsu, Hiroyasu Kataoka, Satoshi Okamoto, Osamu Kitakami, Hajime Aoi

The 9th Perpendicular Magnetic Recording Conference, PMRC 2010　2010年5月17日

詳細を見る詳細を閉じる

19aA-4
Atomic Diffusion Bonding of Wafers with Thin Nanocrystalline Metal Films 国際会議招待有り

Takehito Shimatsu

2nd International IEEE Workshop on Low Temperature Bonding for 3D Integration, LTB-3D 2010　2010年1月19日

詳細を見る詳細を閉じる

Jan. 20, 2010
L11-(Co-Ni)-Pt 垂直磁化膜の磁気特性の温度依存性

島津武仁, 佐山淳一, 青井基, 北上修

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12aB-1
L11-CoPt‐C 規則合金垂直膜の構造と磁気特性

島津武仁, 佐藤英夫, 片岡弘康, 岡本聡, 北上修, 青井基

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12aB-2
L11-(Co1-XMX)50Pt50(M: Ni, Fe, Cr, Mn) 及びCo50(Pt1-XPdX)50 規則合金垂直磁化膜の構造と磁気特性

片岡弘康, 島津武仁, 佐藤英夫, 岡本聡, 北上修, 青井基

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12aB-3
hcp-Co-Pt 垂直磁化ドットの磁化反転における反転核の大きさ

島津武仁, 三塚要, 菊池伸明, 北上修, 青井基

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12pB-1
hcp-CoPt 垂直磁化ドットの磁気異方性に及ぼす加工ダメージの影響

三塚要, 島津武仁, 菊池伸明, 北上修, 青井基

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12pB-3
hcp-Co-Pt 垂直磁化ドットの残留保磁力を決める要因に関する考察

三塚要, 島津武仁, 菊池伸明, 北上修, 青井基

第33回日本磁気学会学術講演会（平成21年）　2009年9月12日

詳細を見る詳細を閉じる

12pB-4
Magnetic anisotropy of L11-type CoPt-M (M:Ni, Fe, Cr and Pd) ordered alloy perpendicular films 国際会議

H. Kataoka, H. Sato, T. Shimatsu, S. Okamoto, O. Kitakami, H. Aoi

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

We-FW5-01
Magnetic properties of L11-type CoPt-C ordered alloy perpendicular films as a function of C content 国際会議

T. Shimatsu, H. Sato, H. Kataoka, S. Okamoto, O. Kitakami, H. Aoi

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

Th-D-10-10
Nucleation size of hcp-CoPt dot arrays characterized by time dependence of coercivity 国際会議

Nobuaki Kikuchi, Kaname Mitsuzuka, Takehito Shimatsu, Osamu Kitakami, Hajime Aoi

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

Th-D-10-15
Reduction of substrate temperature to fabricate L11-type CoPt ordered alloy perpendicular films on glass disks 国際会議

Yuta Toyoda, Takehito Shimatsu, Hideo Sato, Satoshi Okamoto, Osamu Kitakami

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

Th-C-10-17
Remanence coercivity of hcp-CoPt dot arrays 国際会議

Kaname Mitsuzuka, Takehito Shimatsu, Nobuaki Kikuchi, Osamu Kitakami, Hajime Aoi

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

Th-D-10-18
Temperature dependence of magnetic properties for L11-type Co-Ni-Pt ordered alloy films 国際会議

T. Shimatsu, J. Sayama, S. Okamoto, O. Kitakami, H. Aoi

International Conference on Magnetism, ICM 2009　2009年7月26日

詳細を見る詳細を閉じる

Th-D-10-23
Fabrication of L11 type (Co-Ni)-Pt ordered alloy films by sputter deposition for bit-patterned media 国際会議

H. Sato, T. Shimatsu, H. Kataoka, H. Aoi, O. Kitakami, S. Okamoto

53rd Annual Conference on Magnetism and Magnetic Materials, MMM 2008　2008年11月10日

詳細を見る詳細を閉じる

CC-13
Dot arrays of L11 type Co-Pt ordered alloy perpendicular films 国際会議

T. Shimatsu, H. Sato, K. Mitsuzuka, H. Kataoka, H. Aoi, N. Kikuchi, O. Kitakami

53rd Annual Conference on Magnetism and Magnetic Materials, MMM 2008　2008年11月10日

詳細を見る詳細を閉じる

CW-02
Magnetic properties of thin Co-Pt dot arrays with a large uniaxial magnetic anisotropy 国際会議

K. Mitsuzuka, T. Shimatsu, N. Kikuchi, O. Kitakami, H. Muraoka, H. Aoi

53rd Annual Conference on Magnetism and Magnetic Materials, MMM 2008　2008年11月10日

詳細を見る詳細を閉じる

CW-03
Magnetic behavior of single nanostructured magnet 国際会議招待有り

O. Kitakami, S. Okamoto, N. Kikuchi, T. Shimatsu, H. Sato, H. Aoi

International Conference on Advanced Structural and Functional Materials Design 2008　2008年11月10日

詳細を見る詳細を閉じる

IN-220
L11-Co-Pt垂直磁化膜の磁気異方性と飽和磁化

佐藤英夫, 島津武仁, 片岡弘康, 青井基, 岡本聡, 北上修

第32回日本磁気学会学術講演会（平成20年）　2008年9月12日

詳細を見る詳細を閉じる

12aA-3
スパッタ法で作製したL11-Co-Pt垂直磁化膜の構造と磁気特性

島津武仁, 佐藤英夫, 青井基, 岡本聡, 北上修

第32回日本磁気学会学術講演会（平成20年）　2008年9月12日

詳細を見る詳細を閉じる

12aA-4
高Kuを有する極薄hcp-Co-Ptパターン膜の磁気特性

三塚要, 島津武仁, 菊池伸明, 北上修, 村岡裕明, 青井基

第32回日本磁気学会学術講演会（平成20年）　2008年9月12日

詳細を見る詳細を閉じる

12aA-5
Magnetic Behavior of Nanostructured Magnets for Bit Patteｒｎed Media 招待有り

N. Kikuchi, K. Mitsuzuka, S. Okamoto, Kitakami, T. Shimatsu, H. Aoi

第32回日本磁気学会学術講演会（平成20年）　2008年9月12日

詳細を見る詳細を閉じる

13pA-6
L11-Co-Ptパターン膜のドットサイズと磁気特性

島津武仁, 佐藤英夫, 三塚要, 片岡弘康, 青井基, 菊池伸明, 北上修

第32回日本磁気学会学術講演会（平成20年）　2008年9月12日

詳細を見る詳細を閉じる

14a1PS-13
Study on nanostructured magnets for bit patterned media 国際会議招待有り

O. Kitakami, S. Okamoto, N. Kikuchi, T. Shimatsu, H. Aoi

International Disk Forum 2008　2008年7月
Thermal stability and switching field of Hard/Soft stacked perpendicular media 国際会議

T. Shimatsu, K. Kudo, N. Asakula, Y. Inaba, O. Kitakami, S. Okamoto, H. Muraoka, H. Aoi

52nd Annual Conference on Magnetism and Magnetic Materials, MMM 2007　2007年11月5日

詳細を見る詳細を閉じる

FQ-09
Magnetic properties of Hard/Soft stacked perpendicular media with various soft layer thickness 国際会議

T. Shimatsu, A. Satoh, N. Asakura, O. Kitakami, S. Okamoto, H. Muraoka, H. Aoi

52nd Annual Conference on Magnetism and Magnetic Materials, MMM 2007　2007年11月5日

詳細を見る詳細を閉じる

FQ-10
Uniaxial magnetic Co anisotropy in Co and Co-Pt based perpendicular films in relation to lattice deformation 国際会議

T. Shimatsu, Y Okazaki, H. Sato, O. Kitakami, S. Okamoto, T. Sakurai, H. Muraoka, H. Aoi, S. Tani, A. Sakuma

52nd Annual Conference on Magnetism and Magnetic Materials, MMM 2007　2007年11月5日

詳細を見る詳細を閉じる

FQ-11
Magnetic properties of Co-Pt/Co Hard/Soft-stacked dot arrays 国際会議

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Muraoka, H. Aoi

52nd Annual Conference on Magnetism and Magnetic Materials, MMM 2007　2007年11月5日

詳細を見る詳細を閉じる

AC-12
Fabrication of L11 type Co-Pt ordered alloy films by sputter deposition 国際会議

H. Sato, T. Shimatsu, Y. Okazaki, O. Kitakami, S. Okamoto, H. Muraoka, H. Aoi

52nd Annual Conference on Magnetism and Magnetic Materials, MMM 2007　2007年11月5日

詳細を見る詳細を閉じる

HU-01
Magnetization behavior of nanomagnets for patterned media application 国際会議招待有り

Satoshi OKAMOTO, Nobuaki KIKUCHI, Osamu KITAKAMI, Takehito Shimatsu

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pA-03
Investigation of Cylindrical Magnetic Storage Systems 国際会議

Hiroshi YAMADA, Hiroyuki KIKUCHI, Takehito Shimatsu, Isao WATANABE, Hajime AOI, Hiroaki MURAOKA, Junji NUMAZAWA, Yoshihisa NAKAMURA

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pE-13
Fabrication of Co-Pt ordered alloy films with a large uniaxial anisotropy by sputter deposition 国際会議

Hideo SATO, Takehito Shimatsu, Yuko OKAZAKI, Osamu KITAKAMI, Satoshi OKAMOTO, Hiroaki MURAOKA, Hajime AOI

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pB-15
Magnetization reversal of Co-Pt/Co Hard/Soft-stacked dot arrays 国際会議

Kaname MITSUZUKA, Nobuaki KIKUCHI, Takehito Shimatsu, Osamu KITAKAMI, Hiroaki MURAOKA, Hajime AOI

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pC-08
Uniaxial magnetic anisotropy and lattice deformation in Co and Co-Pt based perpendicular films 国際会議

Yuko OKAZAKI, Takehito Shimatsu, Hideo SATO, Osamu KITAKAMI, Satoshi OKAMOTO, Tomoaki SAKURAI, Hiroaki MURAOKA, Hajime AOI, Shunsuke TANII, Akimasa SAKUMA

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

15pD-29
Magnetic properties of Hard/Soft-stacked granular perpendicular media with various soft layer thickness 国際会議

Akira SATOH, Takehito Shimatsu, Noriyuki ASAKURA, Osamu KITAKAMI, Satoshi OKAMOTO, Hiroaki MURAOKA, Hajime AOI

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pB-21
XMCD Study of Pt Orbital Contribution to Perpendicular Magnetization in CoPt Thin-Films 国際会議

N. IShimatsu, Y. TSUTSUI, H. MARUYAMA, N. KAWAMURA, M. SUZUKI, H. OSAWA, Y. OKAZAKI, H. SATO, T. Shimatsu, H. MURAOKA

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

15pD-13
Thermal stability and switching field of Hard/Soft-stacked granular perpendicular media 国際会議

Koji KUDO, Takehito Shimatsu, Noriyuki ASAKURA, Yuki INABA, Osamu KITAKAMI, Satoshi OKAMOTO, Hiroaki MURAOKA, Hajime AOI

The 8th Perpendicular Magnetic Recording Conference, PMRC 2007　2007年10月15日

詳細を見る詳細を閉じる

16pB-20
Hard/Soft スタック垂直媒体の熱安定性と残留保磁力

島津武仁, 朝倉紀之, 稲葉祐樹, 工藤幸司, 北上修, 岡本聡, 村岡裕明, 青井基

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

13aE-8
Hard/Softスタック型CoPt/Coパターン膜の磁化機構

三塚要, 菊池伸明, 島津武仁, 北上修, 村岡裕明, 青井基

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

11pE-5
hard/softスタック垂直媒体のソフト層の厚みと磁化過程

朝倉紀之, 島津武仁, 佐藤啓, 北上修, 岡本聡, 村岡裕明, 青井基

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

13aE-7
スパッタリング法による高磁気異方性Co-Pt規則化合金膜の作成

佐藤英夫, 島津武仁, 岡崎裕子, 北上修, 岡本聡, 村岡裕明, 青井基

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

13pE-11
Co-Pt系垂直磁化膜の一軸磁気異方性と結晶格子の歪み

岡崎裕子, 島津武仁, 佐藤英夫, 北上修, 岡本聡, 桜井伴明, 村岡裕明, 青井基, 岩井俊介, 佐久間昭正

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

13pE-12
Ru 下地上におけるCoPd 薄膜の磁気特性と構造

桜井伴明, 菊池伸明, 岡本聡, 北上修, 島津武仁

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

14aF-7
Possibility of 1 Tbpsi recording by H/S stacked media 招待有り

O. Kitakami, S. Okamoto, N. Kikuchi, T. Shimatsu, H. Aoi

第31回日本応用磁気学会学術講演会（平成19年）　2007年9月11日

詳細を見る詳細を閉じる

14pE-1
Pt content dependence of the switching field distributions of CoPtCr-SiO2 perpendicular media characterized by subtracting the effect of thermal agitation 国際会議

T. Shimatsu, T. Kondo, K. Mitsuzuka, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

10th Joint MMM/Intermag Conference 2007　2007年1月7日

詳細を見る詳細を閉じる

FX-01
Interfacial exchange coupling and magnetization reversal for Co-SiO2/(Co-Pt)-SiO2 hard/soft-stacked perpendicular media 国際会議

T. Shimatsu, Y. Inaba, S. Watanabe, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

10th Joint MMM/Intermag Conference 2007　2007年1月7日

詳細を見る詳細を閉じる

FX-02
Magnetic anisotropy of Co-M-Pt (M=Cr, Mo, Ru, W, Re) perpendicular films epitaxially deposited on various seed layers materials 国際会議

H. Sato, T. Shimatsu, Y. Okazaki, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

10th Joint MMM/Intermag Conference 2007　2007年1月7日

詳細を見る詳細を閉じる

FX-03
Large uniaxial magnetic anisotropy of Co-Pt perpendicular films induced by lattice deformation 国際会議

T. Shimatsu, Y. Okazaki, H. Sato, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

10th Joint MMM/Intermag Conference 2007　2007年1月7日

詳細を見る詳細を閉じる

EV-08
Thickness dependence of the switching field and thermal stability of CoPt/Ru dot arrays 国際会議

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Aoi, H. Muraoka, J. C. Lodder

10th Joint MMM/Intermag Conference 2007　2007年1月7日

詳細を見る詳細を閉じる

EV-14
Investigation of inclined-pad type head for cylindrical magnetic storage system 国際会議

H. Yamada, R. Tsuchiyama, H. Kikuchi, T. Shimatsu, I. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2006　2006年5月8日

詳細を見る詳細を閉じる

BE-01
Large uniaxial magnetic anisotropy in Co100-XPtX/Ru disordered perpendicular films 国際会議

T. Shimatsu, Y. Okazaki, H. Sato, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2006　2006年5月8日

詳細を見る詳細を閉じる

CQ-04
Pt content dependence of magnetic properties of CoPt/Ru patterned films 国際会議

K. Mitsuzuka, N. Kikuchi, T. Shimatsu, O. Kitakami, H. Aoi, H. Muraoka, J. C. Lodder

IEEE International Magnetics Conference, Intermag 2006　2006年5月8日

詳細を見る詳細を閉じる

ER-04
Switching field distribution of CoPtCr-SiO2 perpendicular recording media obtained by subtracting thermal agitation of magnetization 国際会議

T. Shimatsu, T. Kondo, K. Mitsuzuka, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2006　2006年5月8日

詳細を見る詳細を閉じる

FW-02
Magnetic properties to optimize the Ku2 effect in perpendicular recording media 国際会議

H. Sato, T. Shimatsu, T. Kondo, S. Watanabe, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2006　2006年5月8日

詳細を見る詳細を閉じる

FW-03
Effect of thermal agitation on the switching field distributions of CoPtCr-SiO2 perpendicular recording media 国際会議

T. Shimatsu, T. Kondo, K. Mitsuzuka, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

CU-15
Anomalous Hall effect measurement with pulse field on high anisotropy dots of CoPt 国際会議

N. Kikuchi, R. Murillo, J. C. Lodder, K. Mitsuzuka, T. Shimatsu

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

CW-12
CoPtCr-SiO2 media with Ku2 magnetic anisotropy term fabricated with Pd seed layers 国際会議

H. Sato, T. Shimatsu, T. Kondo, S. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura, S. Okamoto, O. Kitakami

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

DE-06
Thermal stability and recording writability of hard/soft stacked perpendicular media 国際会議

Y. Inaba, T. Shimatsu, H. Aoi, H. Muraoka, Y. Nakamura, O. Kitakami

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

DE-07
Study of stacking faults effect on magnetic anisotropy of CoPtCr-SiO2 perpendicular media by synchrotron radiation x-ray diffraction 国際会議

T. Kubo, Y. Kuboki, R. Tanuma, A. Saito, S. Watanabe, T. Shimatsu

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

DE-08
Large uniaxial magnetic anisotropy by lattice deformation in CoPt/Ru perpendicular films 国際会議

T. Shimatsu, H. Sato, Y. Okazaki, H. Aoi, H. Muraoka, Y. Nakamura, S. Okamoto, O. Kitakami

50th Annual Conference on Magnetism and Magnetic Materials, MMM 2005　2005年10月30日

詳細を見る詳細を閉じる

DE-12
CoPtCr-SiO2 perpendicular media for high density recording with a high order magnetic anisotropy energy term 国際会議

T. Shimatsu, H. Sato, T. Oikawa, K. Mitsuzuka, Y. Inaba, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2005　2005年4月4日

詳細を見る詳細を閉じる

GB-05
Preliminary study on (CoPtCr/NiFe)-SiO2 hard/soft-stacked perpendicular recording media 国際会議

Y. Inaba, T. Shimatsu, O. Kitakami, H. Sato, T. Oikawa, H. Muraoka, H. Aoi, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2005　2005年4月4日

詳細を見る詳細を閉じる

CQ-06
Activation volumes in CoPtCr-SiO2 perpendicular recording media 国際会議

Y. Inaba, T. Shimatsu, H. Muraoka, J. D. Dutson, K. O'Grady

IEEE International Magnetics Conference, Intermag 2005　2005年4月4日

詳細を見る詳細を閉じる

CQ-10
Magnetization process of high anisotropy CoPt nanosized dots 国際会議

N. Kikuchi, R. Murillo, J. C. Lodder, K. Mitsuzuka, T. Shimatsu

IEEE International Magnetics Conference, Intermag 2005　2005年4月4日

詳細を見る詳細を閉じる

FW-03
Ku2 term of magnetic anisotropy of CoPtCr-SiO2 media for high density recording 国際会議

T. Shimatsu, H. Sato, K. Mitsuzuka, T. Oikawa, Y. Inaba, H. Aoi, H. Muraoka, Y. Nakamura, O. Kitakami, S. Okamoto

49th Annual Conference on Magnetism and Magnetic Materials, MMM 2004　2004年11月14日

詳細を見る詳細を閉じる

BR-03
Crystallographic analysis of CoPtCr-SiO2 perpendicular recording media with high magnetic anisotropy using synchrotron radiation X-ray diffraction 国際会議

T. Kubo, Y. Kuboki, M. Ohsawa, R. Tanuma, A. Saito, T. Oikawa, H. Uwazumi, T. Shimatsu

49th Annual Conference on Magnetism and Magnetic Materials, MMM 2004　2004年11月14日

詳細を見る詳細を閉じる

CD-09
High potential magnetic anisotropy of CoPtCr-SiO2 perpendicular recording media 国際会議招待有り

T. Shimatsu, T. Oikawa, Y. Inaba, H. Sato, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

15th Magnetic Recording Conference, TMRC 2004　2004年8月

詳細を見る詳細を閉じる

B1
Magnetic anisotropy of CoPtCr-SiO2 perpendicular recording media for high density recording 国際会議招待有り

T. Shimatsu, T. Oikawa, Y. Inaba, H. Sato, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

The Seventh Perpendicular Magnetic Recording Conference, PMRC 2004　2004年5月31日

詳細を見る詳細を閉じる

02pC-02
High magnetic anisotropy and microstructure in CoPtCr(-SiO2) perpendicular films 国際会議

H. Sato, T. Shimatsu, K. Mitsuzuka, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

The Seventh Perpendicular Magnetic Recording Conference, PMRC 2004　2004年5月31日

詳細を見る詳細を閉じる

31pB-04
Thermal agitation and media performance in thin CoPtCr-SiO2 perpendicular recording media 国際会議

Y. Inaba, T. Shimatsu, T. Oikawa, H. Sato, H. Aoi, H. Muraoka, Y. Nakamura

The Seventh Perpendicular Magnetic Recording Conference, PMRC 2004　2004年5月31日

詳細を見る詳細を閉じる

31pB-05
Optimization of SiO2 content and microstructure for CoPtCr-SiO2 perpendicular recording media 国際会議

T. Oikawa, T. Shimatsu, Y. Inaba, I. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

The Seventh Perpendicular Magnetic Recording Conference, PMRC 2004　2004年5月31日

詳細を見る詳細を閉じる

31pB-06
R/W performance of perpendicular double-Layered cylindrical media 国際会議

H. Yamada, T. Shimatsu, I. Watanabe, H. Aoi, H. Muraoka, Y. Nakamura

The Seventh Perpendicular Magnetic Recording Conference, PMRC 2004　2004年5月31日

詳細を見る詳細を閉じる

31pC-01
High perpendicular magnetic anisotropy of CoPtCr/Ru films for granular-type perpendicular media 国際会議

T. Shimatsu, H. Sato, T. Oikawa, Y. Inaba, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

9th Joint MMM/Intermag Conference 2004　2004年1月5日

詳細を見る詳細を閉じる

CP-04
Optimization of the SiO2 content in CoPtCr-SiO2 perpendicular recording media for high-density recording 国際会議

Y. Inaba, T. Shimatsu, T. Oikawa, H. Sato, H. Aoi, H. Muraoka, Y. Nakamura

9th Joint MMM/Intermag Conference 2004　2004年1月5日

詳細を見る詳細を閉じる

CP-05
High potential of thin CoPtCr-SiO2/Ru perpendicular recording media to resist thermal agitation 国際会議

T. Shimatsu, T. Oikawa, Y. Inaba, H. Sato, H. Aoi, H. Muraoka, Y. Nakamura

9th Joint MMM/Intermag Conference 2004　2004年1月5日

詳細を見る詳細を閉じる

BC-09
Development of ultra-high density perpendicular recording media 国際会議

T. Shimatsu, O. Kitakami

International Symposium on Ultra-High Density Spinic Storage Systems, ISSS　2003年10月30日

詳細を見る詳細を閉じる

TA-07
Pt, Cr composition dependence of media performance of CoPtCr-SiO2/Ru perpendicular recording media 国際会議

T. Oikawa, T. Shimatsu, O. Kitakami, Y. Inaba, H. Sato, H. Aoi, H. Muraoka, Y. Nakamura

International Symposium on Ultra-High Density Spinic Storage Systems, ISSS　2003年10月30日

詳細を見る詳細を閉じる

PS-17
Optimization of the SiO2 content in CoPtCr-SiO2 perpendicular recording media for high density recording 国際会議

Y. Inaba, T. Shimatsu, T. Oikawa, H. Sato, H. Aoi, H. Muraoka, Y. Nakamura

International Symposium on Ultra-High Density Spinic Storage Systems, ISSS　2003年10月30日

詳細を見る詳細を閉じる

PS-18
Investigation of cylindrical magnetic storage system 国際会議

H. Yamada, I. Watanabe, T. Shimatsu, H. Aoi, H. Muraoka, Y. Nakamura

International Symposium on Ultra-High Density Spinic Storage Systems, ISSS　2003年10月30日

詳細を見る詳細を閉じる

PS-20
Large perpendicular magnetic anisotropy of CoPtCr/Ru films for granular-type perpendicular media 国際会議

T. Shimatsu, H. Sato, T. Oikawa, Y. Inaba, O. Kitakami, S. Okamoto, H. Aoi, H. Muraoka, Y. Nakamura

International Symposium on Ultra-High Density Spinic Storage Systems, ISSS　2003年10月30日

詳細を見る詳細を閉じる

PS-19
Formation of magnetic cluster and remanence coercivity in granular-type perpendicular media 国際会議

T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2003　2003年3月30日

詳細を見る詳細を閉じる

DR-08
Effect of lattice strain on soft magnetic properties in FeCo/NiFe(Cr) thin films with 2.4 T 国際会議

T. Shimatsu, H. Katada, I. Watanabe, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2003　2003年3月30日

詳細を見る詳細を閉じる

CE-04
Preliminary investigation for a cylindrical magnetic storage system 国際会議

H. Yamada, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2003　2003年3月30日

詳細を見る詳細を閉じる

HE-01
Magnetic cluster size and magnetization curves in perpendicular recording media 国際会議

T. Shimatsu, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura

[NA]PMRC 2003　2003年1月6日

詳細を見る詳細を閉じる

MP-19
Magnetic cluster size and activation volume in perpendicular recording media 国際会議

T. Shimatsu, H. Uwazumi, T. Oikawa, Y. Inaba, H. Muraoka, Y. Nakamura

47th Annual Conference on Magnetism and Magnetic Materials, MMM 2002　2002年11月11日

詳細を見る詳細を閉じる

ES-04
Soft magnetic properties and microstructures in NiFe/FeCo/NiFe films with large saturation magnetization 国際会議

H. Katada, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2002　2002年4月28日

詳細を見る詳細を閉じる

AQ-09
High mobility of surface atoms and induced uniaxial anisotropy in very thin permalloy films 国際会議

H. Katada, T. Shimatsu, H. Watanabe, I. Watanabe, H. Muraoka, Y. Nakamura, Y. Sugita

IEEE International Magnetics Conference, Intermag 2002　2002年4月28日

詳細を見る詳細を閉じる

CC-06
Thermal agitation of magnetization and recording performance of Co(B)/Pd superlattice Perpendicular Recording Media 国際会議

T. Shimatsu, M. Terakawa, I. Watanabe, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2002　2002年4月28日

詳細を見る詳細を閉じる

EP-11
Magnetization reversal of perpendicular recording media characterized using a pulse magnetometer 国際会議

T. Shimatsu, H. Uwazumi, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2002　2002年4月28日

詳細を見る詳細を閉じる

FQ-01
Microstructure and magnetic properties of CoPtCr-SiO2 perpendicular recording media 国際会議

T. Oikawa, M. Nakamura, H. Uwazumi, T. Shimatsu, H. Muraoka, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2002　2002年4月28日

詳細を見る詳細を閉じる

FQ-02
R/W performance and magnetization switching of CoTb/CoCrPt composite perpendicular media 国際会議

H. Uwazumi, T. Shimatsu, Y. Sakai, K. Enomoto, S. Takenoiri, S. Watanabe, H. Muraoka, Y. Nakamura

46th Annual Conference on Magnetism and Magnetic Materials, MMM 2001　2001年11月12日

詳細を見る詳細を閉じる

FB-05
High thermal stability in CoPrTb/CoCrTa composite perpendicular media 国際会議

T. Shimatsu, H. Muraoka, Y. Nakamura, Y. Sonobe, Y. Satodate, K. Muramatsu, I. Watanabe

46th Annual Conference on Magnetism and Magnetic Materials, MMM 2001　2001年11月12日

詳細を見る詳細を閉じる

FB-06
Switching field distributions of 40Gbits/in2 longitudinal media obtained by subtracting thermal agitation of magnetization 国際会議

H. Uwazumi, T. Shimatsu, Y. Kuboki

46th Annual Conference on Magnetism and Magnetic Materials, MMM 2001　2001年11月12日

詳細を見る詳細を閉じる

BC-15
Induced uniaxial anisotropy in very thin soft magnetic films 国際会議

H. Katada, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Nakamura

The 8th Joint MMM-Intermag Conference 2001　2001年1月7日

詳細を見る詳細を閉じる

BR-10
Recording performance of CoCrPt-(Ta,B)/TiCr perpendicular recording media 国際会議

H. Uwazumi, Y. Sakai, A. Otsuki, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Nakamura

The 8th Joint MMM-Intermag Conference 2001　2001年1月7日

詳細を見る詳細を閉じる

DA-13
Thermal agitation of magnetization in CoCrPt perpendicular recording media 国際会議

T. Shimatsu, H. Uwazumi, Y. Sakai, A. Otsuki, I. Watanabe, H. Muraoka, Y. Nakamura

The 8th Joint MMM-Intermag Conference 2001　2001年1月7日

詳細を見る詳細を閉じる

DA-03
Thermal stability in perpendicular recording media 国際会議招待有り

T. Shimatsu, H. Uwazumi, H. Muraoka, Y. Nakamura

The Fifth Perpendicular Magnetic Recording Conference, PMRC 2000　2000年10月23日

詳細を見る詳細を閉じる

25aA-02
Evaluation of thermal stability of perpendicular recording media using a pulse magnetometer 国際会議

T. Shimatsu, R. Yoshida, H. Uwazumi, I. Watanabe, H. Muraoka, Y. Nakamura

The Fifth Perpendicular Magnetic Recording Conference, PMRC 2000　2000年10月23日

詳細を見る詳細を閉じる

23pA-04
Magnetic anisotropy and thermal agitation of magnetization in CoPrTb amorphous perpendicular films 国際会議

T. Shimatsu, K. Muramatsu, I. Watanabe, H. Muraoka, Y. Nakamura

The Fifth Perpendicular Magnetic Recording Conference, PMRC 2000　2000年10月23日

詳細を見る詳細を閉じる

23pA-05
Film magnetostriction and induced uniaxial anisotropy of very thin soft magnetic films 国際会議

H. Katada, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Nakamura, Y. Sugita

The Fifth Perpendicular Magnetic Recording Conference, PMRC 2000　2000年10月23日

詳細を見る詳細を閉じる

3pB-05
Induced uniaxial magnetic anisotropy field in very thin NiFe and CoZrNb films. 国際会議

H. Katada, T. Shimatsu, I. Watanabe, H. Muraoka, Y. Sugita, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2000　2000年4月9日

詳細を見る詳細を閉じる

AR-01
Experimental and theoretical analysis of rotational hysteresis loss in CoCrTa perpendicular recording media 国際会議

T. Shimatsu, S. J. Greaves, K. Muramatsu, I. Watanabe, H. Muraoka, Y. Sugita, Y. Nakamura

IEEE International Magnetics Conference, Intermag 2000　2000年4月9日

詳細を見る詳細を閉じる

EB-04
Effect of a Ti seed-layer on the magnetic properties of CoCrTa double-layered perpendicular media 国際会議

T. Shimatsu, H. Komagome, I. Watanabe, H. Muraoka, Y. Sugita, Y. Nakamura

44th Annual Conference on Magnetism and Magnetic Materials, MMM 1999　1999年11月15日

詳細を見る詳細を閉じる

FA-10
Thermal fluctuation of magnetization in nanocrystalline FePt thin films with high coercivity 国際会議

T. Shimatsu, J. C. Lodder, Y. Sugita, Y. Nakamura

IEEE International Magnetics Conference, Intermag 1999　1999年5月18日

詳細を見る詳細を閉じる

DR-17
Magnetic aftereffect and magnetocrystalline anisotropy of FePt-TaN nanocrystalline thin films 国際会議

T. Shimatsu, E. G. Keim, T. Bolhuis, J. C. Lodder

15th International Colloquium on Magnetic Films and Surfaces　1997年8月

詳細を見る詳細を閉じる

116-117
Latest development of the spin-valve transistor 国際会議招待有り

J. C. Lodder, D. J. Monsma, R. H. Mollema, T. Shimatsu, R. Vlutters

The First Toyota Workshop on Magnetism and Magnetic Materials for High Density Information Storage　1997年4月17日
Development of the spin-valve transistor 国際会議招待有り

D. J. Monsma, T. Shimatsu, R. Vlutters, E. G. Keim, R. H. Mollema, J. C. Lodder

IEEE International Magnetics Conference, Intermag 1997　1997年4月1日

詳細を見る詳細を閉じる

FA-01
Effects of grain size and intergranular coupling on recording characteristics in CoCrTa media 国際会議

H. Sato, A. Kikuchi, J. Nakai, H. Mitsuya, T. Shimatsu, M. Takahashi

IEEE International Magnetics Conference, Intermag 1996　1996年4月9日

詳細を見る詳細を閉じる

GC-05
Effect of surface cleanness on the magnetic properties of CoNiCr and CoCrTa thin-film media fabricated using an ultraclean sputtering process 国際会議

S. Kawakita, T. Sakurai, A. Kikuchi, T. Shimatsu, M. Takahashi

6th International Conference on Magnetic Recording Media　1995年7月

詳細を見る詳細を閉じる

29
Microstructure and intergranular coupling in CoCrTa thin-film media fabricated using an ultraclean sputtering process 国際会議

J. Nakai, A. Kikuchi, K. Nakatani, M. Hirasaka, T. Shimatsu, M. Takahashi

6th International Conference on Magnetic Recording Media　1995年7月

詳細を見る詳細を閉じる

102
Intergranular coupling and recording properties of CoCrTa and CoNiCr thin-film media fabricated using an ultraclean sputtering 国際会議

A. Kikuchi, I. Okamoto, J. Nakai, S. Kawakita, T. Shimatsu, M. Takahashi

6th International Conference on Magnetic Recording Media　1995年7月

詳細を見る詳細を閉じる

103
Intergranular magnetic coupling in CoNiCrPt and CoCrTaPt thin-film media characterized by the temperature dependence of the rotational hysteresis loss 国際会議

T. Shimatsu, D. D. Djayaprawira, A. Endo, N. Iwata, M. Takahashi, T. Wakiyama

6th International Conference on Magnetic Recording Media　1995年7月

詳細を見る詳細を閉じる

104
Effect of Pt on the magnetic anisotropy and intergranular exchange coupling in(Co86Cr12Ta2)100-XPtX and(Co62.5Ni30Cr7.5)100-XPtX thin-film media 国際会議

T. Shimatsu, D. D. Djayaprawira, M. Takahashi, T. Wakiyama

6th International Conference on Magnetic Recording Media　1995年7月

詳細を見る詳細を閉じる

105
Thin Film Media Fabricated under Ultra Clean Sputtering Process 国際会議招待有り

T. Shimatsu, M. Takahashi

1995 Spring Meeting of Material Research Society of Korea　1995年5月
Effect of microstructure on media noise of CoCrTa thin film media fabricated under ultra clean sputtering process 国際会議

J. Nakai, A. Kikuchi, M. Kuwabara, T. Sakurai, T. Shimatsu, M. Takahashi

IEEE International Magnetics Conference, Intermag 1995　1995年4月18日

詳細を見る詳細を閉じる

JA-05
Extremely clean sputtering process and microstructural properties of Ni-Fe films fabricated by this process 国際会議

K. Okuyama, T. Shimatsu, S. Kuji, M. Takahashi

IEEE International Magnetics Conference, Intermag 1995　1995年4月18日

詳細を見る詳細を閉じる

AB-09
High Coercive Force and Low Intergranular Coupling in CoCrTa and CoNiCr Thin Film Media Fabricated under Ultra Clean Sputtering Process 国際会議招待有り

T. Shimatsu, M. Takahashi

1994 IUMRS International Conference on Electronic Materials, IUMRS-ICEM'94　1994年12月
High coercive force and low intergranular coupling in CoCrTa thin film recording media fabricated under ultra clean sputtering process 国際会議

M. Imakawa, S. Ishibashi, A. Hatashita, T. Shimatsu, M. Takahashi

14th International Colloquium on Magnetic Films and Surfaces　1994年8月

詳細を見る詳細を閉じる

B9
Magnetic anisotropy and switching field of metal particulate recording media characterized by magnetic torque analysis 国際会議

M. Igaki, H. Nagamori, T. Shimatsu, M. Takahashi

14th International Colloquium on Magnetic Films and Surfaces　1994年8月

詳細を見る詳細を閉じる

A111
Effect of ultra clean sputtering process on magnetic anisotropy and intergranular coupling in CoNiCr and CoCrTa thin film recording media 国際会議

T. Shimatsu, M. Imakawa, S. Ishibashi, M. Takahashi

14th International Colloquium on Magnetic Films and Surfaces　1994年8月

詳細を見る詳細を閉じる

A112
Magnetic anisotropy and intergranular coupling in CoNiCrPt and CoCrTaPt thin film recording media 国際会議

T. Shimatsu, D. D. Djayaprawira, S. Yokota, M. Takahashi, T. Wakiyama

14th International Colloquium on Magnetic Films and Surfaces　1994年8月

詳細を見る詳細を閉じる

A113
EXPERIMENTAL CHARACTERIZATION OF MAGNETIC ANISOTROPY AND INTERGRANULAR INTERACTION FOR THIN FILM MEDIA 国際会議招待有り

T. Shimatsu, M. Takahashi, M. Suekane, M. Miyamura, K. Yamaguchi, H. Yamasaki

The 3rd IUMRS International Conference on Advanced Materials　1993年8月
SOFT MAGNETISM OF NANOCRYSTALLINE FILMS -RECENT ADVANCES AND PHYSICS- 国際会議招待有り

M. Takahashi, T. SHIMATSU, H. Shoji

The 6th International Conference on Ferrites　1992年9月
Magnetic evaluation of intergranular interaction for thin film media by rotational hysteresis loss analysis 国際会議

M. Takahashi, T. Shimatsu, M. Suekane, M. Miyamura, K. Yamaguchi, H. Yamasaki

International Conference on Magnetic Recording Media　1992年9月

詳細を見る詳細を閉じる

CP-2-41
SOFT MAGNETISM OF SPUTTERED FILMS WITH NANOCRYSTALS 国際会議招待有り

M. Takahashi, T. SHIMATSU

2nd International Symposium on Physics of Magnetic Materials　1992年7月
Magnetic reversal mechanism evaluated by rotational hysteresis loss analysis for the thin film media 国際会議

M. Takahashi, T. Shimatsu, M. Suekane, M. Miyamura, K. Yamaguchi, H. Yamasaki

IEEE International Magnetics Conference, Intermag 1992　1992年4月13日

詳細を見る詳細を閉じる

KA-12
Magnetic Anisotropy and Initial Permeability for the Nanocrystalline Fe Based Sputtered Films 国際会議招待有り

M. Takahashi, T. SHIMATSU

International Colloquium on Magnetic Films and Surfaces1991　1991年8月
SOFT MAGNETISM OF SPUTTERED Fe-SEMI METAL FILMS (NANOCRYSTALLINE EFFECT) 国際会議招待有り

M. Takahashi, T. SHIMATSU

International Symposium on 3d Transition　1991年5月
SOFT MAGNETIC PROPERTIES AND MICROSTRUCTURES FOR THE Fe BASED SPUTTERED FILMS WITH HIGH Bs 国際会議招待有り

M. Takahashi, T. SHIMATSU

Material Research Society 1991 Spring Meeting　1991年4月
Soft magnetism of nanocrystalline Fe based sputtered films with high Bs 国際会議招待有り

M. Takahashi, T. Shimatsu

The European Magnetic Materials and Applications Conference 1991, EMMA ’91　1991年4月
SOFT MAGNETISM OF CRYSTALLINE Fe BASED ALLOY SPUTTERED FILMS 国際会議招待有り

M. Takahashi, T. SHIMATSU

IEEE International Magnetics Conference, Intermag 1990　1990年4月

詳細を見る詳細を閉じる

BA-01
New thin film fabrication technique using a substrate excited by SAW 国際会議

M. Takahashi, A. Fujita, T. Shimatsu, T. Wakiyama, J. Yamada, T. Shiba

IEEE International Magnetics Conference, Intermag 1990　1990年4月

詳細を見る詳細を閉じる

AQ-02
Soft magnetic properties of Fe-N and Fe-Si-N films sputtered in Ar + N2 plasma 国際会議

M. Takahashi, H. Shoji, T. Shimatsu, H. Komaba, T. Wakiyama

IEEE International Magnetics Conference, Intermag 1990　1990年4月

詳細を見る詳細を閉じる

BA-08
The effect of the local anisotropy fluctuation on the permeability for multilayered Co-Zr-Mo-Ni amorphous films 国際会議

M. Takahashi, T. Shimatsu, Y. Shimada, T. Wakiyama

International Symposium on Physics of Magnetic Materials　1987年4月

︎全件表示 ︎最初の5件までを表示

共同研究・競争的資金等の研究課題 18

原子拡散接合法による室温接合技術の開発とデバイス形成への応用競争的資金

2008年4月～継続中
スパッタリングプロセスによる金属薄膜の微細構造の制御に関する研究競争的資金

1990年4月～継続中
高密度磁気記録媒体の開発競争的資金

1989年4月～継続中
ブリルアン散乱による人工アンチフェロ構造におけるテラヘルツ波デバイスの開拓

菊池伸明, 岡本聡, 島津武仁

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2021年4月1日～ 2024年3月31日

詳細を見る詳細を閉じる

本課題では、磁性積層膜を用いた人工フェリ/アンチフェロ構造を用いたテラヘルツ波領域でのスピン波デバイスを提案し、電磁波のエネルギーを効率的に伝送・吸収・変換できる材料探索・制御方法の解明を目指している。本研究で対象とする0.1-1THzという周波数領域は、既存の磁気的測定手法の適用が困難であることから、ファブリー＝ペロー干渉計を用いたブリルアン散乱測定装置の構築を進めた。ブリルアン散乱測定装置は二枚の半透鏡を組み合わせた単純な構造であるものの、光の波長に比べても十分に高い精度での平行性と間隔の制御が必要である。また、磁性体のスピン波による散乱は格子振動による散乱に比べて小さいため、長時間の積算測定に対応するための電気的および環境の安定性が要求される。そこで、研究計画初年度の令和3年度は、ブリルアン散乱測定装置の構築に取り組んだ。まず、高輝度のレーザーの導入により信号強度の増強を測り、波長に合わせた光学系に置き換えた。次に、既有の装置の制御系は主に10－50GHz程度の帯域を想定したものとなっていたため、100GHz以上の帯域に対応できるようより高精度な制御系（ハードウェ・ソフトウェア）の組み込みを行った。さらに、0.1℃以下での温度制御が可能な温度制御系を構築した。これまでに、100GHz以下での格子振動によるピークの計測は可能となっている。しかしながら、より長時間の安定性が求められるスピン波の計測には至っておらず、改善が必要である。また、これらの装置構築と平行しておもにCo/Ru積層膜などの人工反強磁性構造の作製と特性評価も進めた。
高光透過率で屈折率調整が可能な接合界面を有する完全無機の室温接合技術の開発

島津武仁

2020年4月1日～ 2023年3月31日

詳細を見る詳細を閉じる

令和2年度に引き続き，下地酸化膜を形成したウエハを，膜厚1 nm以下の金属薄膜を用いて真空中の原子拡散接合で実施した．令和2年度の結果から，IAD法で形成したSiO2下地膜を形成した石英ウエハに焦点を絞り，Ti，Zr，Nb，Hf，Al，Siを接合金属膜に用いた．接合界面の表面自由エネルギーγ（ブレード法により評価）の膜厚依存性を，熱処理温度の400℃までの範囲で実施した．また，これらの薄膜の接合界面における400～700 nmの波長範囲の光透過率・吸収率を評価し，光学特性の変化から，酸化の促進度合いを評価した．更に，TEMによる構造解析，ならびに，代表的なHfおよびAlについてはEELSによる解析を行った．その結果，下地SiO2膜からの乖離酸素により，これらの接合金属膜が酸化膜として接合界面に形成され，100％の光透過率（金属による光吸収の無い透過率）と2 J/m2を超える大きなγが得られる機構を解明した．特に，AlおよびSiを用いた接合では，膜厚を0.5 nm程度に設定することで，高バンドギャップを有するAl2O3およびSiO2のアモルファス膜による接合界面の形成に成功し，高輝度光に対する優れた耐光性が期待される．最終年度には，高輝度光に対する耐光性に関する議論を進展させ，接合する光学ウエハの屈折率に合わせて，下地酸化膜および接合金属の種類を選択することで，完全透明で耐光性の優れた接合界面を有する完全無機の低温接合技術の提案を行う．
軟磁性微粒子の高周波帯域における磁気損失の起源解明とその設計手法の開発

岡本聡, 島津武仁, 吉田栄吉, 田丸慎吾, 菊池伸明

2020年4月1日～ 2023年3月31日

詳細を見る詳細を閉じる

5G通信における信号品質の確保やパワーデバイスのスイッチング周波数の高周波化に伴い、MHzからGHz帯域での軟磁性微粒子の磁気損失制御が重要な課題となっている。現状ではデバイス実装が先行しており、この周波数帯域における磁気損失に関する学術的理解はほとんど進んでいない。これまでは軟磁性微粒子の集合組織での特性が評価されてきたのみであるが、本研究においては、その構成要素である単一軟磁性微粒子の高周波特性を詳細に調べ、その磁気損失の起源解明を第一の目的としている。次に、この単一軟磁性微粒子の結果を集合組織に反映させる理論モデルを構築し、集合組織として所望の磁気損失特性を実現する設計手法の確立を第二の目的としている。本研究の成果は、今後の高速通信やパワーデバイスに大きく貢献するものである。本年度はSPring-8のXMCD顕微計測を用いて単一扁平磁性粒子の磁化状態観察を行った。その結果、理想的な磁気Vortex構造ではないものの、flux closure状態が複数形成されており、前年度までの低周波領域と高周波領域の吸収ピークに対応する磁化状態であることを確認した。次にトランス結合型透磁率計を用いて、扁平磁性粒子の透磁率スペクトルの粒子サイズ依存性を詳細に計測した。その結果、これまでの低周波領域と高周波領域の吸収ピークだけでなく、中間周波数領域にも吸収ピークが存在していることが分かった。低周波領域の吸収ピークはVortexコアの周回運動で、高周波領域の吸収ピークは磁気Vortex周辺部の一斉励起であるflux closureモードで説明できるが、それに加えて各flux closure状態における一斉励起モードで中間周波数領域の吸収ピークが説明できることが分かった。
高周波スピンダイナミクスのエンジニアリング手法の開発

岡本聡, 島津武仁, 北上修, 菊池伸明

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2017年4月1日～ 2020年3月31日

詳細を見る詳細を閉じる

高周波スピンダイナミクスの制御は磁気記録，スピントロニクス分野において極めて重要な課題である．本研究は高周波スピンダイナミクスに対するエンジニアリング手法の確立を図ることを目的とし，その具体的な実施例として次世代磁気記録技術における従来の物理限界を超える制御手法の提案を目した．様々な層間結合状態にある積層磁性体や磁性グラニュラー薄膜を用い，結合モードによって磁化反転挙動を制御できることを明らかにした．
究極的な高次高分散回折格子の開発

海老塚昇, 島津武仁, 魚本幸, 梶原健, 奥村俊雄, 田中壱, 服部堯, 尾崎忍, 桐野宙治, 岡本隆之, 細畠拓也, 竹田真宏, 山形豊, 佐々木実, 青木和光

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Challenging Exploratory Research

研究機関：Institute of Physical and Chemical Research

2015年4月1日～ 2017年3月31日

詳細を見る詳細を閉じる

Quasi-Bragg (QB) 回折格子として機能する高アスペクト比のVolume binary (VB) 回折格子を、シリコンのサイクルエッチング、酸化膜の形成・除去によって試作した。このシリコンのVB回折格子は可視光においても散乱が少ない極めて滑らかな光学面を持つ。プロトタイプのReflector facet transmission (RFT) 回折格子を鋭角な頂角の回折格子の金型からレプリカ加工した。試作品の回折効率は45~50%程度であった。 30度傾けて切断したQB回折格子をプリズムおよび表面反射ミラーと貼り合わせてQB immersion 回折格子を試作して機能を検証した。
マイクロ波アシスト磁化反転の高効率化技術の開発

岡本聡, 島津武仁, 北上修, 菊池伸明, 佐藤公紀

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2014年4月1日～ 2017年3月31日

詳細を見る詳細を閉じる

マイクロ波アシスト磁化反転技術の高効率化手法について各種検討を行った．まず，ナノドットにおける大振幅歳差運動挙動の高感度定量評価手法を確立した．次に層間結合強度の制御を行った積層磁気性ドットにおいて低周波領域から著しいマイクロ波アシスト効果の増大を確認した．またフェリ磁性体を用いることにより，有効ジャイロ磁気定数を制御することで，マイクロ波アシスト効果の制御が可能であることを実証した．また磁性粒子間の磁気的相互作用がマイクロ波アシスト効果を増大させることを実証した．以上の成果，本技術の実用化を進める上で，マイクロ波アシスト効果の制御が様々なアプローチで可能であることを示すものである．
ＮｄＦｅＢおよびナノコンポジット単一粒子の磁化挙動

北上修, 岡本聡, 菊池伸明, 島津武仁, 柳原美廣

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2012年4月1日～ 2015年3月31日

詳細を見る詳細を閉じる

本研究では，NdFeB磁石の保磁力発生機構を調べるために，単一NdFeBドットの磁化反転挙動を明らかにすることを目的とした．高感度磁化検出および大振幅ナノ秒パルス磁場発生技術を確立し，単一ドットの磁化ダイナミクスを調べた．ナノ秒および直流いずれの磁場でも同一領域を起点に反転核が形成されるが，その後の磁区成長に違いが観測された．後者では隣接磁区が連結し網目状に成長するが，前者では等方的に膨張する．この違いは，ドット内の複数のエネルギー障壁を考慮した熱揺らぎ理論により理解される．以上の結果より，エネルギー障壁の低い領域の局所構造を明らかにし，それを取り除くことが高保磁力化に有効であることが判った．
大気中常温接合の新手法

須賀唯知, 島津武仁, 日暮栄治

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：The University of Tokyo

2011年4月1日～ 2014年3月31日

詳細を見る詳細を閉じる

本研究は、我国が先行する常温接合を世界に先駆けて実用化・量産化に結びつけるための新しい視点として、大気中での常温接合を実現することを目的としている。そのため、従来の常温接合の基礎技術を体系化し、Arイオン衝撃とSiのナノ密着層の組み合わせ、原子拡散接合、大気圧プラズマ照射、水素ラジカル処理などの新しいプロセス、およびその複合プロセスを提案した。またこの過程で、当初予定していなかったSi-Feナノ密着層を適用することで、ポリマーとガラスや、SiCなどの接合が可能であることが判明した。これらの結果を応用し、光マイクロシステムの集積化やデバイス封止技術へ適用可能であることを示した。
マイクロ波アシストによるスイッチング原理および超高密度記録への応用

岡本聡, 菊池伸明, 北上修, 島津武仁, 加藤加藤

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2011年4月1日～ 2014年3月31日

詳細を見る詳細を閉じる

マイクロ波磁場引加による磁化反転の原理研究ならびに磁気記録への適用可能性について検討を行った．垂直磁化ナノドットを用いてマイクロ波磁場下での磁化反転挙動を調べた結果，交換結合長の数１０倍程度の大きなドット径においても，ドット内部のスピン全体での歳差運動を経て磁化反転が起きることが分かった．磁化反転に必要な直流磁場はマイクロ波周波数に比例して減少し，その挙動はドット径に依存した歳差運動モードの周波数依存性に非常に良く対応するものであった．本結果は，極めて制御性の高い次世代記録技術を提供できることを示すものである．
記録用磁性薄膜における巨大磁気異方性の発現機構の解明と制御法の確立

北上修, 岡本聡, 菊池伸明, 島津武仁, 柳原美廣

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (B)

研究機関：Tohoku University

2007年～ 2008年

詳細を見る詳細を閉じる

磁気メモリの高密度化には、高い磁気異方性を示す材料が不可欠である。我々はCo合金薄膜が巨大な磁気異方性を示すことを見出し、それが格子歪(軸比c/a)と密接に関係することを理論・実験から明らかにした。この結果を踏まえて軸比の制御法を検討した。その結果、格子の大きい下地を介在させ磁性層を薄手化することにより軸比を効果的に低減し、磁気異方性を増強できることを明らかにした。磁気異方性が格子歪と単純な関係にあることを示し、その人為的制御を可能にしたことは、将来のメモリ開発にあたり重要な意義を持つ。
柔軟なスピンクラスター配列からなる超高密度磁気記録メディアの研究

中村慶久, 渡辺功, 島津武仁, 村岡裕明

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (A).

研究機関：Tohoku University

1999年～ 2000年

詳細を見る詳細を閉じる

スピンクラスター配列を用いた記録メディアにおいて十分な熱安定性を得るための設計指針を明確にし、あわせて、ニュークリエーション型CoPrTbアモルファス薄膜を用いた垂直スピンクラスター配列の実現と、その磁気記録メディアの作製・基礎特性の評価について検討した。その結果、次のことが明らかとなった。 1.CoCr系のグラニュラー型のスピンクラスターメディアについて熱擾乱の影響を補正した残留保磁力H_oの角度依存性を検討した結果、磁化機構を支配する磁気ポテンシャルの大きさは、S-W型の磁化機構により近似できることが明らかとなった。 2.CoPt-Cr等のグラニュラー型スピンクラスター配列で実現可能なH_oの最大値は、異方性磁界H_kの70〜80%程度(膜厚20nmの場合)であり、十分な熱安定性を得るためには、垂直磁気異方性K_uの値を反磁界エネルギー2πM_s^2の3倍以上にする必要がある。K_u値の増加には、組成の最適化の他にhcp構造の安定形成の促進が必要である。 3.ニュークリエーション型のCoPrTbアモルファス薄膜のK_u値は製膜条件により大きく依存する。製膜条件の最適化を行った結果、膜厚10nmにおいても4×10^6erg/cm^3の大きなK_u値を示すCoPrTb薄膜の作製に成功した。この値はCoPt-Cr等のグラニュラー膜に比べて2〜3倍程度大きい。 4.グラニュラー型のCoCrTa薄膜の上にニュークリエーション型のCoPrTb薄膜を積層した複合型の垂直スピンクラスターメモリーの信号品質(信号とノイズの比S/Nm)は、グラニュラー型のCoCrTa単一膜媒体よりも約10dB(300kFRPIの値)も優れていた。また、グラニュラー型媒体よりも優れた熱安定性を示し、例えば、CoPrTb(10nm)/CoCrTa(20nm)の複合膜では、再生信号の経時減衰が全く観察されなかった。
垂直ハード磁気ディスク装置を用いる超大容量ストレージシステムの研究

中村慶久, 島津武仁, 村岡裕明, 杉田愃, 丹健二

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for Scientific Research (A)

研究機関：TOHOKU UNIVERSITY

1997年～ 1999年

詳細を見る詳細を閉じる

マルチメディアやネットワーク等の分野で膨大な情報を取り扱う大規模情報蓄積システムが強く要求されている。これに垂直磁気記録を用い、大容量性と高速性を同時に兼ね備えた超高密度高速ストレージシステムを構築することが本研究の目標であった。特に、これまで検討が遅れていた垂直磁気記録のための変復調系などの信号処理方式を含むシステム系の研究を重点的に行い、ストレージシステムとしての具体的な性能評価までの研究を進めた。まず、垂直ヘッドディスク系のデバイス研究を発展させ、実用装置に適合可能とするために浮上スライダに実装した単磁極ヘッドを新しく開発した。さらにこれを二層膜媒体に記録ヘッドとして用い、垂直磁化に対する高感度MR再生ヘッドの再生応答を調べて、その適合性を明らかにした。ここで、MRヘッドの再生応答を理論的に解いて解析的な表現式を与え、ヘッドディスク系のパラメータに対する再生応答の予測を可能とした。次に、ヘッドディスク系の出力をデジタル化する高速変復調信号系として、垂直磁気記録用の微分型等化器、並びにPRMLビットエラーアナライザを完成させた。検討の結果、垂直磁化特有の矩形波状のパルス応答をPR4ML復調チャネルに適合させることができ、310kFRPIを越える高密度領域で単磁極ヘッドと二層膜垂直媒体が十分に実用に耐えることを示した。さらに、より高密度化するためには転移性媒体ノイズの低減が必須であることを示し、このために新しい媒体モデルを導入した理論解析から磁気的な揺らぎサイズを小さくすることが有効であること、及び、垂直磁気記録のノイズのビット毎の相関を打ち消してエラーレートを向上させる信号処理方式についても研究を行った。上記の媒体ノイズモデルと理論的な再生応答理論を用いて今後の垂直磁気記録のポテンシャルを理論的に予測し、10nm程度まで媒体の磁気構造を微細化することで100Gbits/inch^2以上が達成できることを明らかにした。
低交換相互作用によるナノスピンクラスターを利用した超高密度磁気記録薄膜媒体の研究

島津武仁

1994年～ 1994年

詳細を見る詳細を閉じる

(Co_<92.5-X>Ni_XCr_<7.5>)_<100-Y>Pt_Y(X=10〜40,Y=0〜15)を磁性層として作製した薄膜媒体の、結晶磁気異方性、交換定数および粒間相互作用について検討し、ナノスピンクラスターを利用した超高密度磁気記録媒体の実現に関する基礎物性的な検討を行なった。その結果、X=25〜30at%程度のNi組成域においてY=9at%程度までPt量を増加させることで、結晶磁気異方性は2倍程度増加し、粒間の交換相互作用は1/2程度まで低減することが、回転ヒステリシス損失およびΔMプロットの測定より明らかとなった。特にPtの添加による交換相互作用の低下は真性的な交換定数の低下に主に起因しており、本材料系を用いた場合には、9at%以上のPtを添加した組成域がナノスピンクラスターの形成に適していることが明らかとなった。スピンクラスターの大きさについて磁気的に評価するため、本材料系を始めとする各種のCo基薄膜媒体について、薄膜磁気ヘッドを用いたDC erased noise量の計測を行なった。その結果、結晶粒間の交換相互作用の低減にともないDC erased noiseの極大値が低減し、スピンクラスターの大きさが小さくなっていることが明らかとなった。しかし、CoNiCrPt材料系を用いた場合には、Ptの添加により交換相互作用が低下するものの、結晶粒の磁化容易軸(c軸)が膜面内から膜法線方向へと徐々に変化してしまい、膜面内の磁化機構が変化してしまうことが明らかとなった。本材料系を用いたナノスピンクラスターの安定形成には、c軸を膜面に平行に配向させ、さらに、結晶粒径を低減することが、今度の課題となることを明らかにした。
スパッタ薄膜記録媒体の非線形磁化反転機構

島津武仁

1990年～ 1990年
磁化容易面および微細磁区をもつ二重六万CoーFe合金系電子材料に関する研究

脇山徳雄, 島津武仁, 田中寿郎, 高橋研, 宮崎照宣

提供機関：Japan Society for the Promotion of Science

制度名：Grants-in-Aid for Scientific Research

研究種目：Grant-in-Aid for General Scientific Research (B)

研究機関：Tohoku University

1989年～ 1990年

詳細を見る詳細を閉じる

1.CoーFe合金多結晶のHCP 相試料(0〜1.0%Fe)およびDHCP相試料(1.2〜3.0%Fe)について、圧延誘導磁気異方性を測定した。圧延率依存性の側定から、CoおよびCoー3.0%Feについて、圧延率10〜20%で、誘導一軸磁気異方性定数(Kur)の大きさ3×10^5 erg/cm^3が得られた。 2.Fe濃度依存性の測定から、一軸異方性の容易方向は、HCP相試料では圧延方向と垂直(Kur〈0)であり、DHCP相試料では圧延方向と平行(Kur〉0)であることが明らかにされた。 3.KurのFe濃度依存性は磁場中冷却効果による誘導磁気異方性のFe濃度依存性と対応しており、また、両者共CoーFe合金の結晶磁気異方性定数(K_1)のFe濃度依存性と対応している。結晶粒配向の観測結果を考慮して、Kurの起源はK_1と圧延組織にあることが明らかにされた。 4.FeーCo/ZnO積層膜をrfスパッタ法で作製し、その軟磁気特性の膜厚および組成依存性を調べた。保磁力と交流透磁率(10MHz)の間には対応がみられ、20と84wt%Co付近では透磁率はピ-ク(約900と約700)を示す。 5.(Fe_<1ーx>Co_x)_<1ーy> Nb_y(0≦x ≦1.0,0≦y ≦0.2:重量比)膜をrfスパッタ法で作製し、その軟磁気特性の組成および焼鈍温度依存性を調べた。773Kで3600S焼鈍した膜の保磁力は、y=0.05およびx=0.3ー0.8付近で、最小値400A/mであり、その膜の交流透磁率は800、飽和磁束密度は2Tである。

︎全件表示 ︎最初の5件までを表示

社会貢献活動 5

文部科学省指定SSH(スーパーサイエンスハイスクール)事業

2018年9月8日～

詳細を見る詳細を閉じる

「フロンティアスピリットを持つ「サイエンスリーダー」の育成を目指して」講師
文部科学省指定SSH(スーパーサイエンスハイスクール)事業

2017年9月16日～

詳細を見る詳細を閉じる

「フロンティアスピリットを持つ「サイエンスリーダー」の育成を目指して」講師
パワーエレクトロニクスと半導体産業の新展開

2016年10月31日～

詳細を見る詳細を閉じる

みやぎ高度電子機械産業振興協議会及び一般社団法人エレクトロニクス実装学会共催の半導体分野セミナー
文部科学省指定SSH(スーパーサイエンスハイスクール)事業

2016年9月3日～

詳細を見る詳細を閉じる

「理数系教育のパイオニアハイスクールをめざして～山梨の中核拠点校として、世界に羽ばたく科学技術系人材を育てる～」講師
文部科学省指定SSH(スーパーサイエンスハイスクール)事業

2015年9月5日～

詳細を見る詳細を閉じる

「理数系教育のパイオニアハイスクールをめざして～山梨の中核拠点校として、世界に羽ばたく科学技術系人材を育てる～」講師