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Mikihiko Ogane

Section

Graduate School of Engineering

Job title

Professor

Degree

博士（工学）（東北大学）
修士（工学）（東北大学）

researchmap

https://researchmap.jp/read0065509

J-GLOBAL ID

200901014246713641

Committee Memberships 8

日本磁気学会　国際担当理事

2025/06 - Present
ATF 高機能センサ研究会　委員

2024/08 - Present
電気学会　調査専門委員会委員

2019/04 - Present
日本磁気学会　企画委員

2018/04 - Present
応用物理学会　スピントロニクス研究会幹事

2009/04 - Present
日本磁気学会　編集・論文委員

2014/12 - 2017/05
応用物理学会　代議員

2013/01 - 2017/01
応用物理学会・スピントロニクス研究会　庶務会計幹事

2011/01 - 2012/12

Show all ︎Show first 5

Professional Memberships 4

一般社団法人電気学会

2023/04 - Present
日本生体磁気学会

2022/06 -
応用物理学会
日本磁気学会

Research Interests 5

量子磁気センサ
磁性薄膜
トンネル接合
MRAM
Spintronics

Research Areas 2

Nanotechnology/Materials / Nanobioscience /
Nanotechnology/Materials / Nanomaterials /

Awards 13

研究奨励賞

2022/05　みやぎ産業科学振興基金　量子スピントロニクスセンサの超高感度化に関する研究
Applied Physics Express 2021 Spotlight

2021/11　Sub-pT magnetic field detection by tunnel magneto-resistive sensors
第6回青葉工学振興会賞

2012/12/07　(財)青葉工学振興会
第22回トーキン科学技術振興財団研究奨励賞

2012/03　第22回トーキン科学技術振興財団研究奨励賞
第38回（2025年度）独創性を拓く先端技術大賞特別賞

2025/07　産経新聞社　量子スピントロニクスセンサを利用したSpin-MRI装置の開発
44th JSAP paper award

2023/03　Sub-pT magnetic field detection by tunnel magneto-resistive sensors
JPSJ Papers of Editor’s Choice

2021/06　Brownian motion of magnetic skyrmions in one- and two-dimensional systems
支部貢献賞

2018/12　応用物理学会
39th MSJ paper award

2015/09　Dependence of Magnetic Damping on Temperature and Crystal Orientation in Epitaxial Fe4N Thin Films
第34回応用物理学会優秀論文賞

2012/09/11　応用物理学会
日本磁気学会論文賞

2008/09　日本磁気学会
日本応用磁気学会学術奨励賞

2007/08　日本応用磁気学会
Young Researcher Award ISAM2-2003

2003/10/08　日本MRS

Show all ︎Show 5

Papers 305

Tunnel-magnetoresistance sensors with sub-pT detectivity for detecting bio-magnetic fields Invited Peer-reviewed

Takafumi Nakano, Kosuke Fujiwara, Mikihiko Oogane

Applied Physics Letters　126　(16)　160503-160503　2025/04/21

DOI： 10.1063/5.0263879 　
Magnetic anisotropy and damping in epitaxial Fe-Co-Ni binary and ternary alloy thin films

Tomoya Ueno, Takafumi Nakano, Masakiyo Tsunoda, Shogo Yamashita, Takayuki Hojo, Mikihiko Oogane

Journal of Magnetism and Magnetic Materials　172841-172841　2025/01
Publisher: Elsevier BV
DOI： 10.1016/j.jmmm.2025.172841 　

ISSN： 0304-8853
Fabrication of half-metallic Co<inf>2</inf>FeAl<inf>x</inf>Si<inf>1–</inf><inf>x</inf> thin film with small magneto-crystalline anisotropy constant K<inf>1</inf>

Takayuki Hojo, Hiromi Hamasaki, Masakiyo Tsunoda, Mikihiko Oogane

Journal of Magnetism and Magnetic Materials　601　2024/07/01

DOI： 10.1016/j.jmmm.2024.172144 　

ISSN： 0304-8853
Development of Tunnel Magneto-Resistive Sensors

Mikihiko Oogane

IEICE Transactions on Electronics　E107.C　(6)　171-175　2024/06

DOI： 10.1587/transele.2023SEI0001 　

ISSN： 0916-8524

eISSN： 1745-1353
Evaluation of Pipe Thickness by Magnetic Hammer Test with a Tunnel Magnetoresistive Sensor

Jun Ito, Yudai Igarashi, Ryota Odagiri, Shigetaka Suzuki, Hiroshi Wagatsuma, Kazuhiro Sugiyama, Mikihiko Oogane

Sensors　24　(5)　2024/03

DOI： 10.3390/s24051620 　

eISSN： 1424-8220
Temperature and bias voltage dependences of magnetic tunnel junction with FeAlSi electrode

Shoma Akamatsu, Byung Hun Lee, Yasen Hou, Masakiyo Tsunoda, Mikihiko Oogane, Geoffrey S.D. Beach, Jagadeesh S. Moodera

APL Materials　12　(2)　2024/02/01

DOI： 10.1063/5.0189570 　

eISSN： 2166-532X
生体磁気計測のためのセンサおよび計測技術の最新動向トンネル磁気抵抗センサを用いた室温生体磁場計測

藤原耕輔, 中野貴文, 福島隼人, 稲垣大, 石田誠, 熊谷静以, 松崎斉, 中里信和, 大兼幹彦

日本生体磁気学会誌　37　(1)　80-81　2024
Publisher: 日本生体磁気学会
ISSN： 0915-0374
Vortex Chaotic Dynamics in a Cross-Tie Domain Wall

Muftah Al-Mahdawi, Mikihiko Oogane

2024 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2024 - Proceedings　2024

DOI： 10.1109/INTERMAGShortPapers61879.2024.10576810 　
Development of Magnetic Hammering Test using Tunnel Magneto-resistive Sensor

Jun Ito, Yudai Igarashi, Mikihiko Oogane

IEEJ Transactions on Fundamentals and Materials　144　(8)　325-330　2024

DOI： 10.1541/ieejfms.144.325 　

ISSN： 0385-4205

eISSN： 1347-5533
Enhanced sensitivity and thermal tolerance in tunnel magnetoresistance sensor using Ta-doped CoFeSiB soft magnetic layer

Takafumi Nakano, Kosuke Fujiwara, Masakiyo Tsunoda, Seiji Kumagai, Mikihiko Oogane

Applied Physics Letters　123　(7)　2023/08/14
Publisher: AIP Publishing
DOI： 10.1063/5.0162276 　

ISSN： 0003-6951

eISSN： 1077-3118

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We developed a tunnel magnetoresistance (TMR) sensor consisting of a CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) and a CoFeSiB amorphous soft magnetic layer. This multilayer structure is promising for a high-sensitivity sensor because a giant TMR ratio of the MTJ and a small anisotropy field Hk of the free layer can be obtained simultaneously. However, the soft magnetic properties of the CoFeSiB layer disappear when it is annealed at above the crystallization temperature (around 300 °C), which determines the thermal tolerance of the TMR sensor and limits improvements to the sensor's sensitivity and applications. In this study, we doped the CoFeSiB layer with various amounts of Ta to raise its crystallization temperature. TMR sensors using the Ta-doped CoFeSiB layers showed thermal tolerance to annealing temperatures above 425 °C, whereas the sensor with the undoped CoFeSiB layer was tolerant to annealing temperatures up to 325 °C. As well, the Ta doping effectively reduced Hk of the CoFeSiB layer, which resulted in a sensitivity of 50%/Oe, over three times higher than the sensor with the undoped CoFeSiB layer. These results pave the way toward next-generation TMR sensors having higher sensitivity and wider applicability.
Prediction of Magnetocrystalline Anisotropy Constant in FeCoNi Alloys Using Machine Learning

Ren Sudo, Mikihiko Oogane

2023 IEEE International Magnetic Conference - Short Papers (INTERMAG Short Papers)　2023/05
Publisher: IEEE
DOI： 10.1109/intermagshortpapers58606.2023.10228569 　
TaFeB spacer for soft magnetic composite free layer in CoFeB/MgO/CoFeB-based magnetic tunnel junction Peer-reviewed

Takafumi Nakano, Kosuke Fujiwara, Seiji Kumagai, Yasuo Ando, Mikihiko Oogane

Applied Physics Letters　122　(7)　072405　2023/02/13

DOI： 10.1063/5.0132866 　
Tunnel anisotropic magnetoresistance in magnetic tunnel junctions using FeAlSi Peer-reviewed

S. Akamatsu, T. Nakano, Muftah Al-Mahdawi, W. Yupeng, M. Tsunoda, Y. Ando, M. Oogane

AIP Advances　13　(2)　025005　2023/02/01

DOI： 10.1063/9.0000440 　
Low magnetic damping constant in half-metallic Co2FeAl Heusler alloy thin films grown by molecular beam epitaxy Peer-reviewed

Takayuki Hojo, Nobuki Tezuka, Takafumi Nakano, Masakiyo Tsunoda, Mikihiko Oogane

AIP Advances　13　(2)　025204　2023/02/01

DOI： 10.1063/9.0000419 　
Development of Magnetocardiograph without Magnetically Shielded Room Using High-Detectivity TMR Sensors

Koshi Kurashima, Makoto Kataoka, Takafumi Nakano, Kosuke Fujiwara, Seiichi Kato, Takenobu Nakamura, Masaki Yuzawa, Masanori Masuda, Kakeru Ichimura, Shigeki Okatake, Yoshitaka Moriyasu, Kazuhiro Sugiyama, Mikihiko Oogane, Yasuo Ando, Seiji Kumagai, Hitoshi Matsuzaki, Hidenori Mochizuki

Sensors　23　(2)　646-646　2023/01/06
Publisher: MDPI AG
DOI： 10.3390/s23020646 　

eISSN： 1424-8220

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A magnetocardiograph that enables the clear observation of heart magnetic field mappings without magnetically shielded rooms at room temperatures has been successfully manufactured. Compared to widespread electrocardiographs, magnetocardiographs commonly have a higher spatial resolution, which is expected to lead to early diagnoses of ischemic heart disease and high diagnostic accuracy of ventricular arrhythmia, which involves the risk of sudden death. However, as the conventional superconducting quantum interference device (SQUID) magnetocardiographs require large magnetically shielded rooms and huge running costs to cool the SQUID sensors, magnetocardiography is still unfamiliar technology. Here, in order to achieve the heart field detectivity of 1.0 pT without magnetically shielded rooms and enough magnetocardiography accuracy, we aimed to improve the detectivity of tunneling magnetoresistance (TMR) sensors and to decrease the environmental and sensor noises with a mathematical algorithm. The magnetic detectivity of the TMR sensors was confirmed to be 14.1 pTrms on average in the frequency band between 0.2 and 100 Hz in uncooled states, thanks to the original multilayer structure and the innovative pattern of free layers. By constructing a sensor array using 288 TMR sensors and applying the mathematical magnetic shield technology of signal space separation (SSS), we confirmed that SSS reduces the environmental magnetic noise by −73 dB, which overtakes the general triple magnetically shielded rooms. Moreover, applying digital processing that combined the signal average of heart magnetic fields for one minute and the projection operation, we succeeded in reducing the sensor noise by about −23 dB. The heart magnetic field resolution measured on a subject in a laboratory in an office building was 0.99 pTrms and obtained magnetocardiograms and current arrow maps as clear as the SQUID magnetocardiograph does in the QRS and ST segments. Upon utilizing its superior spatial resolution, this magnetocardiograph has the potential to be an important tool for the early diagnosis of ischemic heart disease and the risk management of sudden death triggered by ventricular arrhythmia.
Magnetic Hammer Testing with Tunnel Magnetoresistive Sensors

Jun Ito, Muftah Al-Mahdawi, Mikihiko Oogane

IEEE Transactions on Magnetics　59　(11)　1-1　2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/tmag.2023.3282988 　

ISSN： 0018-9464

eISSN： 1941-0069
Ac Susceptibility Measurement Using a Vibrating Sample Magnetometer

Muftah Al-Mahdawi, Mikihiko Oogane

IEEE Transactions on Magnetics　59　(11)　1-1　2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/tmag.2023.3300268 　

ISSN： 0018-9464

eISSN： 1941-0069
Scalp attached tangential magnetoencephalography using tunnel magneto-resistive sensors

Akitake Kanno, Nobukazu Nakasato, Mikihiko Oogane, Kosuke Fujiwara, Takafumi Nakano, Tadashi Arimoto, Hitoshi Matsuzaki, Yasuo Ando

Scientific Reports　12　(1)　2022/12
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-022-10155-6 　

eISSN： 2045-2322

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Abstract Non-invasive human brain functional imaging with millisecond resolution can be achieved only with magnetoencephalography (MEG) and electroencephalography (EEG). MEG has better spatial resolution than EEG because signal distortion due to inhomogeneous head conductivity is negligible in MEG but serious in EEG. However, this advantage has been practically limited by the necessary setback distances between the sensors and scalp, because the Dewar vessel containing liquid helium for superconducting quantum interference devices (SQUIDs) requires a thick vacuum wall. Latest developments of high critical temperature (high-T_c) SQUIDs or optically pumped magnetometers have allowed closer placement of MEG sensors to the scalp. Here we introduce the use of tunnel magneto-resistive (TMR) sensors for scalp-attached MEG. Improvement of TMR sensitivity with magnetic flux concentrators enabled scalp-tangential MEG at 2.6 mm above the scalp, to target the largest signal component produced by the neural current below. In a healthy subject, our single-channel TMR-MEG system clearly demonstrated the N20m, the initial cortical component of the somatosensory evoked response after median nerve stimulation. Multisite measurement confirmed a spatially and temporally steep peak of N20m, immediately above the source at a latency around 20 ms, indicating a new approach to non-invasive functional brain imaging with millimeter and millisecond resolutions.
Magnetic tunnel junctions using epitaxially grown FeAlSi electrode with soft magnetic property Peer-reviewed

Shoma Akamatsu, Mikihiko Oogane, Masakiyo Tsunoda, Yasuo Ando

AIP Advances　12　(7)　075021-075021　2022/07/01
Publisher: AIP Publishing
DOI： 10.1063/5.0094619 　

eISSN： 2158-3226

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Magnetic tunnel junctions (MTJs) with (001)-oriented D0₃-FeAlSi epitaxial films, which have both soft magnetic properties and surface flatness, were fabricated and characterized. A tunnel magnetoresistance (TMR) ratio of 121% was observed, and a relatively low switching field was also confirmed, reflecting the soft magnetic property of FeAlSi. However, the results of the cross-sectional TEM image of the MTJ and the bias dependence of the TMR ratio indicate that the FeAlSi/MgO interface is probably oxidized. Therefore, since an insertion layer at the interface can suppress oxidation and further improve the TMR ratio, MTJs using FeAlSi epitaxial films are promising structures suitable for applications such as MTJ-based magnetic sensors and worthy of further investigation.
Guidelines for attaining optimal soft magnetic properties in FeAlSi films Peer-reviewed

Shoma Akamatsu, Mikihiko Oogane, Masakiyo Tsunoda, Yasuo Ando

Applied Physics Letters　120　(24)　242406-242406　2022/06/13
Publisher: AIP Publishing
DOI： 10.1063/5.0086322 　

ISSN： 0003-6951

eISSN： 1077-3118

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Nm-order FeAlSi epitaxial films with a partially D0₃-ordered structure were grown on MgO substrates, and ideal soft magnetic properties were obtained. We found that the sign of the magnetocrystalline anisotropy constant K₁ changes with increasing annealing temperature for certain FeAlSi compositions. This is caused by a change in the volume balance of the ordered phases with the annealing process and the point at which K₁ ∼ 0 shifts to the Al-rich concentration as the degree of D0₃-ordering decreases. K₁ was precisely measured by ferromagnetic resonance under the optimal condition, and the value of 1.6 × 10² (erg/cc) was obtained, which is comparable to that of bulk. The uniaxial component of the magnetic anisotropy due to magnetostriction was small, and a fourfold symmetric component due to magnetocrystalline anisotropy was dominant.
Control of sensitivity in vortex-type magnetic tunnel junction magnetometer sensors by the pinned layer geometry Peer-reviewed

Motoki Endo, Muftah Al-Mahdawi, Mikihiko Oogane, Yasuo Ando

Journal of Physics D: Applied Physics　55　(19)　195001-195001　2022/05/12
Publisher: IOP Publishing
DOI： 10.1088/1361-6463/ac5080 　

ISSN： 0022-3727

eISSN： 1361-6463

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Abstract The tuning of sensitivity and dynamic range in linear magnetic sensors is required in various applications. We demonstrate the control and design of the sensitivity in magnetic tunnel junction (MTJ) sensors with a vortex-type sensing layer. In this work, we develop sensor MTJs with NiFe sensing layers having a vortex magnetic configuration. We demonstrate that by varying the pinned layer size, the sensitivity to magnetic field is tuned linearly. We obtain a high magnetoresistance ratio of 140%, and we demonstrate a controllable sensitivity from 0.85% Oe⁻¹ to 4.43% Oe⁻¹, while keeping the vortex layer fixed in size. We compare our experimental results with micromagnetic simulations. We find that the linear displacement of vortex core by an applied field makes the design of vortex sensors simple. The control of the pinned layer geometry is an effective method to increase the sensitivity, without affecting the vortex state of the sensing layer. Furthermore, we propose that the location of the pinned layer can be used to realize more sensing functionalities from a single sensor.
Observation of unconventional spin-polarization induced spin–orbit torque in L1₂-ordered antiferromagnetic Mn₃Pt thin films Peer-reviewed

Longjie Yu, Shutaro Karube, Min Liu, Masakiyo Tsunoda, Mikihiko Oogane, Yasuo Ando

Applied Physics Express　15　(3)　033002-033002　2022/03/01
Publisher: IOP Publishing
DOI： 10.35848/1882-0786/ac52d7 　

ISSN： 1882-0778

eISSN： 1882-0786

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Abstract Non-collinear antiferromagnets exhibit richer magneto-transport properties compared to nonmagnetic materials due to the topological spin structure they possess, which allows us to manipulate the charge-spin conversion more freely by taking advantage of the chirality. In this work, we explore the unconventional spin–orbit torque of L1₂-ordered Mn₃Pt with a triangular spin structure. We observed an unconventional spin–orbit torque along the x-direction for the (001)-oriented L1₂ Mn₃Pt and found that it has a sign reversal behavior relative to the crystalline orientation. This generation of unconventional spin–orbit torque can be interpreted as stemming from the magnetic spin Hall effect.
最新のセンサー系から見た心臓磁場計測技術と脳磁場計測に向けた展望室温動作TMRセンサーを用いたリアルタイム心磁場および体性感覚誘発脳磁場の計測

藤原耕輔, 菅野彰剛, 中野貴文, 熊谷静似, 松崎斉, 有本直, 大兼幹彦, 中里信和, 安藤康夫

日本生体磁気学会誌　35　(1)　76-77　2022
Publisher: 日本生体磁気学会
ISSN： 0915-0374
最新のセンサー系から見た心臓磁場計測技術と脳磁場計測に向けた展望室温動作TMRセンサーを用いたリアルタイム心磁場および体性感覚誘発脳磁場の計測

藤原耕輔, 菅野彰剛, 中野貴文, 熊谷静似, 松崎斉, 有本直, 大兼幹彦, 中里信和, 安藤康夫

日本生体磁気学会誌　35　(1)　76-77　2022
Publisher: 日本生体磁気学会
ISSN： 0915-0374
Deep Learning Models for Magnetic Cardiography Edge Sensors Implementing Noise Processing and Diagnostics Peer-reviewed

Sadman Sakib, Mostafa M. Fouda, Muftah Al-Mahdawi, Attayeb Mohsen, Mikihiko Oogane, Yasuo Ando, Zubair Md. Fadlullah

IEEE Access　10　2656-2668　2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/access.2021.3138976 　

eISSN： 2169-3536
Sub-pT magnetic field detection by tunnel magneto-resistive sensors

Mikihiko Oogane, Kosuke Fujiwara, Akitake Kanno, Takafumi Nakano, Hiroshi Wagatsuma, Tadashi Arimoto, Shigemi Mizukami, Seiji Kumagai, Hitoshi Matsuzaki, Nobukazu Nakasato, Yasuo Ando

Applied Physics Express　14　(12)　123002-123002　2021/12/01
Publisher: IOP Publishing
DOI： 10.35848/1882-0786/ac3809 　

ISSN： 1882-0778

eISSN： 1882-0786

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<title>Abstract</title> We developed tunnel magneto-resistive (TMR) sensors based on magnetic tunnel junctions (MTJs) that are able to detect a weak, sub-pT, magnetic field at a low frequency. Small detectivities of 0.94 pT/Hz^1/2 at 1 Hz and 0.05 pT/Hz^1/2 at 1 kHz were achieved by lowering the resistance of MTJs and enhancement of the signal using a thick CoFeSiB layer and magnetic flux concentrators. We demonstrated real-time measurement of magnetocardiography (MCG) and nuclear magnetic resonance (NMR) of protons using developed sensors. This result shows that both MCG and NMR can be measured by the same measurement system with ultra-sensitive TMR sensors.
室温生体磁気計測の進歩:SQUIDを超えて TMRセンサの原理と心磁図計測

大兼幹彦, 菅野彰剛, 藤原耕輔, 中野貴文, 熊谷静似, 松崎斉, 中里信和, 安藤康夫

臨床神経生理学　49　(5)　299-299　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
室温生体磁気計測の進歩:SQUIDを超えて頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学　49　(5)　300-300　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
第32回小児脳機能研究会:臨床神経生理からみた小児の機能評価-中枢から末梢まで- 頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学　49　(5)　371-371　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
室温生体磁気計測の進歩:SQUIDを超えて TMRセンサの原理と心磁図計測

大兼幹彦, 菅野彰剛, 藤原耕輔, 中野貴文, 熊谷静似, 松崎斉, 中里信和, 安藤康夫

臨床神経生理学　49　(5)　299-299　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
室温生体磁気計測の進歩:SQUIDを超えて頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学　49　(5)　300-300　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
第32回小児脳機能研究会:臨床神経生理からみた小児の機能評価-中枢から末梢まで- 頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学　49　(5)　371-371　2021/10
Publisher: (一社)日本臨床神経生理学会
ISSN： 1345-7101

eISSN： 2188-031X
Quadratic magnetoelectric effect during field cooling in sputter grown Cr2O3 films

Muftah Al-Mahdawi, Tomohiro Nozaki, Mikihiko Oogane, Hiroshi Imamura, Yasuo Ando, Masashi Sahashi

Physical Review Materials　5　(9)　2021/09/14
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevmaterials.5.094406 　

eISSN： 2475-9953
Brownian Motion of Magnetic Skyrmions in One- and Two-Dimensional Systems Peer-reviewed

Soma Miki, Yuma Jibiki, Eiiti Tamura, Minori Goto, Mikihiko Oogane, Jaehun Cho, Ryo Ishikawa, Hikaru Nomura, Yoshishige Suzuki

Journal of the Physical Society of Japan　90　(8)　083601-083601　2021/08/15
Publisher: Physical Society of Japan
DOI： 10.7566/jpsj.90.083601 　

ISSN： 0031-9015

eISSN： 1347-4073
Noise-Removal from Spectrally-Similar Signals Using Reservoir Computing for MCG Monitoring

Sadman Sakib, Mostafa M. Fouda, Muftah Al-Mahdawi, Attayeb Mohsen, Mikihiko Oogane, Yasuo Ando, Zubair Md Fadlullah

ICC 2021 - IEEE International Conference on Communications　2021/06
Publisher: IEEE
DOI： 10.1109/icc42927.2021.9500993 　
Tunnel magnetoresistance in magnetic tunnel junctions with FeAlSi electrode

Shoma Akamatsu, Mikihiko Oogane, Zhenhu Jin, Masakiyo Tsunoda, Yasuo Ando

AIP Advances　11　(4)　2021/04/01
Publisher: American Institute of Physics Inc.
DOI： 10.1063/5.0041571 　

ISSN： 2158-3226
Serial MTJ-Based TMR Sensors in Bridge Configuration for Detection of Fractured Steel Bar in Magnetic Flux Leakage Testing

Zhenhu Jin, Muhamad Arif Ihsan Mohd Noor Sam, Mikihiko Oogane, Yasuo Ando

Sensors　21　(2)　668-668　2021/01/19
Publisher: MDPI AG
DOI： 10.3390/s21020668 　

eISSN： 1424-8220

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Thanks to high sensitivity, excellent scalability, and low power consumption, magnetic tunnel junction (MTJ)-based tunnel magnetoresistance (TMR) sensors have been widely implemented in various industrial fields. In nondestructive magnetic flux leakage testing, the magnetic sensor plays a significant role in the detection results. As highly sensitive sensors, integrated MTJs can suppress frequency-dependent noise and thereby decrease detectivity; therefore, serial MTJ-based sensors allow for the design of high-performance sensors to measure variations in magnetic fields. In the present work, we fabricated serial MTJ-based TMR sensors and connected them to a full Wheatstone bridge circuit. Because noise power can be suppressed by using bridge configuration, the TMR sensor with Wheatstone bridge configuration showed low noise spectral density (0.19 μV/Hz0.5) and excellent detectivity (5.29 × 10−8 Oe/Hz0.5) at a frequency of 1 Hz. Furthermore, in magnetic flux leakage testing, compared with one TMR sensor, the Wheatstone bridge TMR sensors provided a higher signal-to-noise ratio for inspection of a steel bar. The one TMR sensor system could provide a high defect signal due to its high sensitivity at low lift-off (4 cm). However, as a result of its excellent detectivity, the full Wheatstone bridge-based TMR sensor detected the defect even at high lift-off (20 cm). This suggests that the developed TMR sensor provides excellent detectivity, detecting weak field changes in magnetic flux leakage testing.
Measurement of somatosensory evoked magnetic fields at room temperature using a TMR sensor system

Kanno Akitake, Oogane mikihiko, Fujiwara Kosuke, Matsuzaki Hitoshi, Ando Yasuo, Nakasato Nobukazu

Transactions of Japanese Society for Medical and Biological Engineering　59　752-753　2021
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.Annual59.752 　

ISSN： 1347-443X

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<p>Measurement of somatosensory magnetic evoked fields (SEFs), using a magnetoencephalography (MEG) system with superconducting quantum interference devices (SQUIDs), are one of the most popular diagnostic tools to evaluate and localize brain function in human. However, wall size of liquid helium container for SQUIDs has been constituting a barrier to minimize sensor-source distance, the most important factor for spatial resolution. We recently achieved a success to measure human magneto-cardiogram and spontaneous alpha activity of MEG at room temperature using newly developed tunnel magneto-resistive (TMR) sensors. Here we applied a TMR sensor system to measure SEFs, challenging MEG signals due to their weakness. In a normal volunteer subject, using a standard stimulation protocol of median nerve stimulus, a TMR sensor system combined with magnetic flux concentrators, and a signal averaging technique up to 5,000 times, we successfully demonstrated a clear N20m peak, the first and weakest component of SEFs.</p>
Measurement of somatosensory evoked magnetic fields at room temperature using a TMR sensor system

Kanno Akitake, Oogane mikihiko, Fujiwara Kosuke, Matsuzaki Hitoshi, Ando Yasuo, Nakasato Nobukazu

Transactions of Japanese Society for Medical and Biological Engineering　59　243-243　2021
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.Annual59.243 　

ISSN： 1347-443X

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<p>Measurement of somatosensory magnetic evoked fields (SEFs), using a magnetoencephalography (MEG) system with superconducting quantum interference devices (SQUIDs), are one of the most popular diagnostic tools to evaluate and localize brain function in human. However, wall size of liquid helium container for SQUIDs has been constituting a barrier to minimize sensor-source distance, the most important factor for spatial resolution. We recently achieved a success to measure human magneto-cardiogram and spontaneous alpha activity of MEG at room temperature using newly developed tunnel magneto-resistive (TMR) sensors. Here we applied a TMR sensor system to measure SEFs, challenging MEG signals due to their weakness. In a normal volunteer subject, using a standard stimulation protocol of median nerve stimulus, a TMR sensor system combined with magnetic flux concentrators, and a signal averaging technique up to 5,000 times, we successfully demonstrated a clear N20m peak, the first and weakest component of SEFs.</p>
トンネル磁気抵抗素子を用いた室温脳磁計による体性感覚誘発磁界の測定

菅野彰剛, 大兼幹彦, 藤原耕輔, 松崎斉, 安藤康夫, 中里信和

日本生体磁気学会誌　34　(1)　112-113　2021
Publisher: 日本生体磁気学会
ISSN： 0915-0374
Highly-sensitive magnetic sensor for detecting magnetic nanoparticles based on magnetic tunnel junctions at a low static field

Z. Jin, Thomas Myeongseok Koo, Myeong Soo Kim, M. Al-Mahdawi, M. Oogane, Y. Ando, Young Keun Kim

AIP Advances　11　(1)　015046-015046　2021/01/01
Publisher: AIP Publishing
DOI： 10.1063/9.0000189 　

eISSN： 2158-3226
Detection of Small Magnetic Fields Using Serial Magnetic Tunnel Junctions with Various Geometrical Characteristics

Zhenhu Jin, Yupeng Wang, Kosuke Fujiwara, Mikihiko Oogane, Yasuo Ando

Sensors　20　(19)　5704-5704　2020/10/07
Publisher: MDPI AG
DOI： 10.3390/s20195704 　

eISSN： 1424-8220

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Thanks to their high magnetoresistance and integration capability, magnetic tunnel junction-based magnetoresistive sensors are widely utilized to detect weak, low-frequency magnetic fields in a variety of applications. The low detectivity of MTJs is necessary to obtain a high signal-to-noise ratio when detecting small variations in magnetic fields. We fabricated serial MTJ-based sensors with various junction area and free-layer electrode aspect ratios. Our investigation showed that their sensitivity and noise power are affected by the MTJ geometry due to the variation in the magnetic shape anisotropy. Their MR curves demonstrated a decrease in sensitivity with an increase in the aspect ratio of the free-layer electrode, and their noise properties showed that MTJs with larger junction areas exhibit lower noise spectral density in the low-frequency region. All of the sensors were able detect a small AC magnetic field (Hrms = 0.3 Oe at 23 Hz). Among the MTJ sensors we examined, the sensor with a square-free layer and large junction area exhibited a high signal-to-noise ratio (4792 ± 646). These results suggest that MTJ geometrical characteristics play a critical role in enhancing the detectivity of MTJ-based sensors.
AI Aided Noise Processing of Spintronic Based IoT Sensor for Magnetocardiography Application

Attayeb Mohsen, Muftah Al-Mahdawi, Mostafa M. Fouda, Mikihiko Oogane, Yasuo Ando, Zubair Md Fadlullah

ICC 2020 - 2020 IEEE International Conference on Communications (ICC)　2020/06
Publisher: IEEE
DOI： 10.1109/icc40277.2020.9148617 　
Efficiency of ultrafast optically induced spin transfer in Heusler compounds

Daniel Steil, Jakob Walowski, Felicitas Gerhard, Tobias Kiessling, Daniel Ebke, Andy Thomas, Takahide Kubota, Mikihiko Oogane, Yasuo Ando, Johannes Otto, Andreas Mann, Moritz Hofherr, Peter Elliott, John Kay Dewhurst, Günter Reiss, Laurens Molenkamp, Martin Aeschlimann, Mirko Cinchetti, Markus Münzenberg, Sangeeta Sharma, Stefan Mathias

Physical Review Research　2　(2)　2020/05/20
Publisher: American Physical Society
DOI： 10.1103/PhysRevResearch.2.023199 　

ISSN： 2643-1564
High-Temperature Magnetic Tunnel Junction Magnetometers Based on L1$_0$-PtMn Pinned Layer

Sina Ranjbar, Muftah Al-Mahdawi, Mikihiko Oogane, Yasuo Ando

IEEE Sensors Letters　4　(5)　1-4　2020/05
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
DOI： 10.1109/lsens.2020.2991654 　

eISSN： 2475-1472
Controlling domain configuration of the sensing layer for magnetic tunneling junctions by using exchange bias

Sina Ranjbar, Muftah Al-Mahdawi, Mikihiko Oogane, Yasuo Ando

AIP Advances　10　(2)　025119-025119　2020/02/01
Publisher: AIP Publishing
DOI： 10.1063/1.5130486 　

eISSN： 2158-3226
Large spin signals in n+ -Si/MgO/ Co2Fe0.4Mn0.6Si lateral spin-valve devices Peer-reviewed

T. Koike, M. Oogane, M. Tsunoda, Y. Ando

Journal of Applied Physics　127　(8)　085306-1-085306-8　2020/02
Fabrication and evaluation of highly c-plane oriented Mn3Sn thin films Peer-reviewed

T. Ikeda, M. Tsunoda, M. Oogane, S. Oh, T. Morita, Y. Ando

AIP Advances　10　015310-1-015310-5　2020/01
Fabrication of soft-magnetic FeAlSi thin films with nm-order thickness for the free layer of magnetic tunnel junction based sensors Peer-reviewed

S. Akamatsu, M. Oogane, M. Tsunoda, Y. Ando

AIP Advances　10　015302-1-015302-4　2020/01
Composition dependence of the secondorder interfacial magnetic anisotropy for MgO/CoFeB/Ta films Peer-reviewed

T. Ogasawara, M. Oogane, M. Al-Mahdawi, M. Tsunoda, Y. Ando

AIP Advances　9　125053-1-125053-5　2019/12
Polycrystalline Co2Fe0.4Mn0.6Si Heusler alloy thin films with high B2 ordering and small magnetic anisotropy for magnetic tunnel junction based sensors Peer-reviewed

N. Kudo, M. Oogane, M. Tsunoda, Y. Ando

AIP Advances　9　125036-1-125036-4　2019/12
Effect of second-order magnetic anisotropy on nonlinearity of conductance in CoFeB/MgO/CoFeB magnetic tunnel junction for magnetic sensor devices Peer-reviewed

T. Ogasawara, M. Oogane, M. Al-Mahdawi, M. Tsunoda, Y. Ando

Scientific Reports　9　17018-1-17018-9　2019/11
Investigation of a Magnetic Tunnel Junction Based Sensor for the Detection of Defects in Reinforced Concrete at High Lift-Off

Muhamad Arif Ihsan Mohd Noor Sam, Zhenhu Jin, Mikihiko Oogane, Yasuo Ando

Sensors　19　(21)　4718-4718　2019/10/30
Publisher: MDPI AG
DOI： 10.3390/s19214718 　

eISSN： 1424-8220

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Magnetic flux leakage (MFL) testing is a method of non-destructive testing (NDT), whereby the material is magnetized, and when a defect is present, the magnetic flux lines break out of the material. The magnitude of the leaked magnetic flux decreases as the lift-off (distance from the material) increases. Therefore, for detection at high lift-off, a sensitive magnetic sensor is required. To increase the output sensitivity, this paper proposes the application of magnetic tunnel junction (MTJ) sensors in a bridge circuit for the NDT of reinforced concrete at high lift-off. MTJ sensors were connected to a full-bridge circuit, where one side of the arm has two MTJ sensors connected in series, and the other contains a resistor and a variable resistor. Their responses towards a bias magnetic field were measured, and, based on the results, the sensor circuit sensitivity was 0.135 mV/mT. Finally, a reinforced concrete specimen with a 1 cm gap in the center was detected. The sensor module (with an amplifier and low pass filter circuits) could determine the gap even at 50 cm, suggesting that MTJ sensors have the potential to detect defects at high lift-off values and have a promising future in the field of NDT.
Composition dependence of exchange anisotropy in PtxMn100−x/CoyFe100-y films Peer-reviewed

S. Ranjbar, M. Tsunoda, M. Al-Mahdawi, M. Oogane, Y. Ando

IEEE Magnetics Letters　10　4505905-1-4505905-5　2019/10
Development of TMR Magnetic Sensors with High Sensitivity and Reliability Invited Peer-reviewed

Mikihiko Oogane, Takafumi Nakano

Magnetics Japan　14　(5)　260-267　2019/10
Improvement of Large Anomalous Hall Effect in Polycrystalline Antiferromagnetic Mn3+xSn Thin Films Peer-reviewed

Ikeda Tomoki, Tsunoda Masakiyo, Oogane Mikihiko, Oh Seungjun, Morita Tadashi, Ando Yasuo

IEEE TRANSACTIONS ON MAGNETICS　55　(7)　2019/07

DOI： 10.1109/TMAG.2019.2899223 　

ISSN： 0018-9464
Controlled growth and magnetic property of a-plane-oriented Mn3Sn thin films Peer-reviewed

Oh Seungjun, Morita Tadashi, Ikeda Tomoki, Tsunoda Masakiyo, Oogane Mikihiko, Ando Yasuo

AIP ADVANCES　9　(3)　2019/03

DOI： 10.1063/1.5079688 　

ISSN： 2158-3226
Serial magnetic tunnel junction based sensors for detecting far-side pitsin metallic specimens Peer-reviewed

Zhenhu Jin, Muhamad Arif Ihsan, Mikihiko Oogane, Kousuke Fujiwara, Yasuo Ando

Japanese Journal of AppliedPhysics　58　043003-1-043003-6　2019/03

DOI： 10.7567/1347-4065/aafe71 　
Composition dependence of exchange anisotropy in PtxMn1−x/Co70Fe30 films Peer-reviewed

Sina Ranjbar, Masakiyo Tsunoda, Mikihiko Oogane, Yasuo Ando

Japanese Journal of Applied Physics　58　043001-1-043001-5　2019/03

DOI： 10.7567/1347-4065/ab03e3 　
Epitaxial L10-MnAl Thin Films With High Perpendicular Magnetic Anisotropy and Small Surface Roughness Peer-reviewed

Most Shahnaz Parvin, Mikihiko Oogane, Miho Kubota, Masakiyo Tsunoda, Yasuo Ando

EEE TRANSACTIONS ON MAGNETICS　54　(11)　3401704-1-3401704-4　2018/11

DOI： 10.1109/TMAG.2018.2834553 　

ISSN： 0018-9464
Anomalous Hall effect in polycrystalline Mn3Sn thin films Peer-reviewed

Tomoki Ikeda, Masakiyo Tsunoda, Mikihiko Oogane, Seungjun Oh, Tadashi Morita, Yasuo Ando

APPLIED PHYSICS LETTERS　113　222405-1-222405-5　2018/11

DOI： 10.1063/1.5051495 　
Effects of annealing temperature on sensing properties of magnetic-tunnel-junction-based sensors with perpendicular syntheticantiferromagnetic Co/Pt pinned layer Peer-reviewed

Takahiro Ogasawara, Mikihiko Oogane, Masakiyo Tsunoda, Yasuo Ando

Japanese Journal of AppliedPhysics　57　(11)　110308-1-110308-4　2018/10

DOI： 10.7567/JJAP.57.110308 　
Large exchange coupling field in perpendicular synthetic antiferromagnetic structures with CoPt alloy Peer-reviewed

Takahiro Ogasawara, Mikihiko Oogane, Masakiyo Tsunoda, Yasuo Ando

Japanese Journal of Applied Physics　57　088004　2018/07
Annealing effect on interlayer exchange coupling in perpendicularly magnetized synthetic antiferromagnetic structure based on Co/Pd multilayers with ultrathin Ru spacer Peer-reviewed

Takafumi Nakano, Mikihiko Oogane, Yasuo Ando

Japanese Journal of Applied Physics　57　073001　2018/06
Low magnetic damping and large negative anisotropic magnetoresistance in half-metallic Co2-xMn1+xSi Heusler alloy films grown by molecular beam epitaxy Peer-reviewed

Mikihiko Oogane, Anthony P. McFadden, Kenji Fukuda, Masakiyo Tsunoda, Yasuo Ando, Chris J. Palmstrom

APPLIED PHYSICS LETTERS　112　262407　2018/06
Fourfold symmetric anisotropic magnetoresistance in half-metallic Co2MnSi Heusler alloy thin films Peer-reviewed

Mikihiko Oogane, Anthony P. McFadden, Yohei Kota, Tobias L. Brown-Heft, Masakiyo Tsunoda, Yasuo Ando, Chris J. Palmstrom

Japanese Journal of Applied Physics　57　063001　2018/04
Magnetic-sensor performance evaluated from magneto-conductance curve in magnetic tunnel junctions using in-plane or perpendicularly magnetized synthetic antiferromagnetic reference layers Peer-reviewed

T. Nakano, M. Oogane, T. Furuichi, Y. Ando

AIP Advances　8　(4)　045011　2018/04/01
Publisher: American Institute of Physics Inc.
DOI： 10.1063/1.5027768 　

ISSN： 2158-3226
Room Temperature Magnetoencephalography and Magnetocardiography Measurements using TMR Sensors

Fujiwara Kousuke, Oogane Mikihiko, Kanno Akitake, Imada Masahiro, Jono Junichi, Terauchi Takashi, Okuno Tetsuo, Aritomi Yuuji, Hashimoto Kiyofumi, Morikawa Masahiro, Tsuchida Masaaki, Nakasato Nobukazu, Ando Yasuo

JSAP Annual Meetings Extended Abstracts　2018.1　2250-2250　2018/03/05
Publisher: The Japan Society of Applied Physics
DOI： 10.11470/jsapmeeting.2018.1.0_2250 　

eISSN： 2436-7613
Realization of a Spin-Wave Switch Based on the Spin-Transfer-Torque Effect Peer-reviewed

Thomas Meyer, Thomas Br ̈ acher, Frank Heussner, Alexander A. Serga, Hiroshi Naganuma, Koki Mukaiyama, Mikihiko Oogane, Yasuo Ando, Burkard Hillebrands, d Philipp Pirro

IEEE MAGNETICS LETTERS　9　3102005-1-3102005-5　2018/02

DOI： 10.1109/LMAG.2018.2803737 　
Characterization of spin-transfer-torque effect induced magnetization dynamics driven by short current pulses Peer-reviewed

T. Meyer, T. Brächer, F. Heussner, A. A. Serga, H. Naganuma, K. Mukaiyama, M. Oogane, Y. Ando, B. Hillebrands, P. Pirro

Applied Physics Letters　112　(2)　022401　2018/01/08
Publisher: American Institute of Physics Inc.
DOI： 10.1063/1.5011721 　

ISSN： 0003-6951
Magnetocardiography and magnetoencephalography measurements at room temperature using tunnel magneto-resistance sensors Peer-reviewed

Kosuke Fujiwara, Mikihiko Oogane, Akitake Kanno, Masahiro Imada, Junichi Jono, Takashi Terauchi, Tetsuo Okuno, Yuuji Aritomi, Masahiro Morikawa, Masaaki Tsuchida, Nobukazu Nakasato, Yasuo Ando

Applied Physics Express　11　023001　2018/01
Structural and Magnetic Properties in Mn2VAl Full-Heusler Epitaxial Thin Films Peer-reviewed

Kenji Fukuda, Mikihiko Oogane, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　53　(11)　2017/11

DOI： 10.1109/TMAG.2017.2697078 　

ISSN： 0018-9464

eISSN： 1941-0069
Observation of Magnetoresistance Effect in n-Type Non-Degenerate Germanium With Co2Fe0.4Mn0.6Si Heusler Alloy Electrodes Peer-reviewed

Takeo Koike, Mikihiko Oogane, Tetsurou Takada, Hidekazu Saito, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　53　(11)　2017/11

DOI： 10.1109/TMAG.2017.2704780 　

ISSN： 0018-9464

eISSN： 1941-0069
Magnetic sensor based on serial magnetic tunnel junctions for highly sensitive detection of surface cracks Peer-reviewed

Zhenhu Jin, Mikihiko Oogane, Kosuke Fujiwara, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　122　(17)　113903　2017/11

DOI： 10.1063/1.5001098 　

ISSN： 0021-8979

eISSN： 1089-7550
DC Bias Reversal Behavior of Spin-Torque Ferromagnetic Resonance Spectra in CoFeB/MgO/CoFeB Perpendicular Magnetic Tunnel Junction Peer-reviewed

Tian Yu, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　53　(9)　2017/09

DOI： 10.1109/TMAG.2017.2707081 　

ISSN： 0018-9464

eISSN： 1941-0069
Wide-dynamic-range magnetic sensor based on magnetic tunnel junctions using perpendicularly magnetized synthetic antiferromagnetic reference layer Peer-reviewed

T. Nakano, M. Oogane, T. Furuichi, Y. Ando

2017 IEEE International Magnetics Conference, INTERMAG 2017　2017/08/10
Publisher: Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/INTMAG.2017.8007558 　
Magnetic properties of ferrimagnetic (Mn1-xCox)2VAl full-Heusler epitaxial thin films Peer-reviewed

K. Fukuda, M. Oogane, Y. Ando

2017 IEEE International Magnetics Conference, INTERMAG 2017　2017/08/10
Publisher: Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/INTMAG.2017.8007971 　
L1

Oogane Mikihiko, Watanabe Kenta, Saruyama Haruaki, Hosoda Masaki, Shahnaz Parvin, Kurimoto Yuta, Kubota Miho, Ando Yasuo

Jpn. J. Appl. Phys.　56　(8)　0802A2　2017/06/01
Publisher: Institute of Physics
DOI： 10.7567/JJAP.56.0802A2 　

ISSN： 0021-4922

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L1<inf>0</inf>-ordered MnAl thin films were epitaxially grown by sputtering. The film composition dependences of structural and magnetic properties were systematically investigated in the MnAl thin films. Both the L1<inf>0</inf>-ordered parameter and the perpendicular magnetic anisotropy energy strongly depended on the composition of the MnAl thin films. The MnAl thin films with a Mn composition of 53–54 at. % showed both the highest L1<inf>0</inf>-ordered parameter and the perpendicular magnetic anisotropy. The substrate and annealing temperatures were optimized to improve the magnetic properties and surface morphology. We have fabricated MnAl thin films with both a very high K<inf>u</inf>of 12 × 10⁶erg/cm³and a small surface roughness of ca. 0.2 nm by optimizing the film composition and substrate and annealing temperatures. These results are useful guidelines for the fabrication of highly L1<inf>0</inf>-ordered MnAl thin films with a large perpendicular magnetic anisotropy.
Cobalt substituted L1

Watanabe Kenta, Oogane Mikihiko, Ando Yasuo

Jpn. J. Appl. Phys.　56　(8)　0802B1　2017/06/01
Publisher: Institute of Physics
DOI： 10.7567/JJAP.56.0802B1 　

ISSN： 0021-4922

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The Co composition dependences of the structural and magnetic properties of L1<inf>0</inf>-(MnAl)<inf>1−</inf><inf>x</inf>Co<inf>x</inf>alloy films were investigated. The lattice constants of (MnAl)<inf>1−</inf><inf>x</inf>Co<inf>x</inf>films gradually changed with increasing Co content while maintaining the L1<inf>0</inf>-ordered structure below x = 0.08. The saturation magnetization gradually decreased with increasing Co content, and perpendicular magnetic anisotropy was observed below x = 0.08. In addition, Co substitution markedly improved the surface roughness of the films by decreasing the substrate temperature of (MnAl)<inf>1−</inf><inf>x</inf>Co<inf>x</inf>films. We found that both a high magnetic anisotropy and a small surface roughness can be obtained by the substitution of Co atoms into MnAl films.
Grain-Size-Dependent Low-Temperature Electrical Resistivity of Polycrystalline Co2MnAl Heusler Alloy Thin Films Peer-reviewed

Resul Yilgin, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM　30　(6)　1577-1584　2017/06

DOI： 10.1007/s10948-016-3957-5 　

ISSN： 1557-1939

eISSN： 1557-1947
Cobalt substituted L10-MnAl thin films with large perpendicular magnetic anisotropy Peer-reviewed

Kenta Watanabe, Mikihiko Oogane, Yasuo Ando

Jpn. J. Appl. Phys.　2017/06
Estimation of surface crack dimensional characteristics by an eddy current method using a single magnetic tunnel junction device Peer-reviewed

Z. Jin, M. Abe, M. Oogane, K. Fujiwara, Y. Ando

Jpn. J. Appl. Phys.　56　(7)　73001-73001　2017/06
Publisher: Institute of Physics
DOI： 10.7567/JJAP.56.073001 　

ISSN： 0021-4922

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Eddy current testing plays a significant role in detecting surface defects in a nondestructive testing field. The magnetoresistive sensors based on magnetic tunnel junction devices attracted considerable attention for their use in eddy current testing owing to their high sensitivity and capability of being miniaturized. We investigated the detection of surface cracks in eddy current testing using a single magnetic tunnel junction. A perpendicular component with a secondary magnetic field from an eddy current was measured by using an optimized rectangular magnetic tunnel junction device with an aspect ratio of 4 (20 × 80 µm²). Furthermore, according to the extracted ΔX and ΔV from the sensor output signal, surface cracks with various widths (0.1, 0.3, and 0.5 mm) and depths (0.5, 1.0, 1.5, and 3.0 mm) in aluminum specimens were successfully estimated using the magnetic tunnel junction device in eddy current testing when an excitation frequency of 1000 Hz was used.
L10-ordered MnAl thin films with high perpendicular magnetic anisotropy Invited Peer-reviewed

Mikihiko Oogane, Kenta Watanabe, Haruaki Saruyama, Masaki Hosoda, Parvin Shahnaz, Yuta Kurimoto, Miho Kubota, Yasuo Ando

Jpn. J. Appl. Phys.　2017/06
Fabrication of orientation-controlled nanocomposite Nd2Fe14B/Mo/α–Fe multilayer films Peer-reviewed

K. Kobayashi, D. Ogawa, K. Koike, H. Kato, M. Oogane, T. Miyazaki, Y. Ando, M. Itakura

Journal of Physics, Conference series　2017
Publisher: IOP Institute of Physics
Experimental Investigation of the Temperature-Dependent Magnon Density and Its Influence on Studies of Spin-Transfer-Torque-Driven Systems Peer-reviewed

Thomas Meyer, Thomas Braecher, Frank Heussner, Alexander A. Serga, Hiroshi Naganuma, Koki Mukaiyama, Mikihiko Oogane, Yasuo Ando, Burkard Hillebrands, Philipp Pirro

IEEE MAGNETICS LETTERS　8　318005　2017

DOI： 10.1109/LMAG.2017.2734773 　

ISSN： 1949-307X
Magnetic tunnel junctions using perpendicularly magnetized synthetic antiferromagnetic reference layer for wide-dynamic-range magnetic sensors Peer-reviewed

T. Nakano, M. Oogane, T. Furuichi, Y. Ando

APPLIED PHYSICS LETTERS　110　(1)　2017/01

DOI： 10.1063/1.4973462 　

ISSN： 0003-6951

eISSN： 1077-3118
Investigation of magnetic sensor properties of magnetic tunnel junctions with superparamagnetic free layer at low frequencies for biomedical imaging applications Peer-reviewed

Kyohei Ishikawa, Mikihiko Oogane, Kousuke Fujiwara, Junichi Jono, Masaaki Tsuchida, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　55　(12)　2016/12

DOI： 10.7567/JJAP.55.123001 　

ISSN： 0021-4922

eISSN： 1347-4065
Influence of L1(0) order parameter on Gilbert damping constants for FePd thin films investigated by means of time-resolved magneto-optical Kerr effect Peer-reviewed

Satoshi Iihama, Akimasa Sakuma, Hiroshi Naganuma, Mikihiko Oogane, Shigemi Mizukami, Yasuo Ando

PHYSICAL REVIEW B　94　(17)　174425　2016/11

DOI： 10.1103/PhysRevB.94.174425 　
Fabrication of highly ordered Co2Fe0.4Mn0.6Si Heusler alloy films on Si substrates Peer-reviewed

Takeo Koike, Mikihiko Oogane, Atsuo Ono, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　55　(8)　2016/08

DOI： 10.7567/JJAP.55.088001 　

ISSN： 0021-4922

eISSN： 1347-4065
Effect of annealing on Curie temperature and phase transition in La0.55Sr0.08Mn0.37O3 epitaxial films grown on SrTiO3 (100) substrates by reactive radio frequency magnetron sputtering Peer-reviewed

T. Ichinose, H. Naganuma, T. Miyazaki, M. Oogane, Y. Ando, T. Ueno, N. Inami, K. Ono

MATERIALS CHARACTERIZATION　118　37-43　2016/08

DOI： 10.1016/j.matchar.2016.05.002 　

ISSN： 1044-5803

eISSN： 1873-4189
Magnetic Tunnel Junctions With [Co/Pd]-Based Reference Layer and CoFeB Sensing Layer for Magnetic Sensor Peer-reviewed

Takafumi Nakano, Mikihiko Oogane, Takamoto Furuichi, Kenichi Ao, Hiroshi Naganuma, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　52　(7)　2016/07

DOI： 10.1109/TMAG.2016.2518188 　

ISSN： 0018-9464

eISSN： 1941-0069
Magnetic field-controlled hysteresis loop bias in orthogonal exchange-spring coupling composite magnetic films Peer-reviewed

Jun Jiang, Tian Yu, Rui Pan, Qin-Tong Zhang, Pan Liu, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Xiufeng Han

APPLIED PHYSICS EXPRESS　9　(6)　2016/06

DOI： 10.7567/APEX.9.063003 　

ISSN： 1882-0778

eISSN： 1882-0786
Observation of single-spin transport in an island-shaped CoFeB double magnetic tunnel junction prepared by magnetron sputtering Peer-reviewed

Thamrongsin Siripongsakul, Hiroshi Naganuma, Andras Kovacs, Amit Kohn, Mikihiko Oogane, Yasuo Ando

PHILOSOPHICAL MAGAZINE　96　(4)　310-319　2016/02

DOI： 10.1080/14786435.2015.1131343 　

ISSN： 1478-6435

eISSN： 1478-6443
Controlling Magnetization Switching and DC Transport Properties of Magnetic Tunnel Junctions by Mircowave Injection Peer-reviewed

Cheng Xin, Yu Guo Liu, Lin Shi, Tian Yu, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

7TH IEEE INTERNATIONAL NANOELECTRONICS CONFERENCE (INEC) 2016　2016

ISSN： 2159-3523
Ultrafast demagnetization of L1(0) FePt and FePd ordered alloys Peer-reviewed

Satoshi Iihama, Yuta Sasaki, Hiroshi Naganuma, Mikihiko Oogane, Shigemi Mizukami, Yasuo Ando

JOURNAL OF PHYSICS D-APPLIED PHYSICS　49　(3)　2016/01

DOI： 10.1088/0022-3727/49/3/035002 　

ISSN： 0022-3727

eISSN： 1361-6463
Modification of the Interface Nanostructure and Magnetic Properties in Nd-Fe-B Thin Films Peer-reviewed

Kunihiro Koike, Takanao Kusano, Daisuke Ogawa, Keisuke Kobayashi, Hiroaki Kato, Mikihiko Oogane, Takamichi Miyazaki, Yasuo Ando, Masaru Itakura

NANOSCALE RESEARCH LETTERS　11　2016/01

DOI： 10.1186/s11671-016-1227-x 　

ISSN： 1556-276X
Systematic Investigation on Correlation Between Sensitivity and Nonlinearity in Magnetic Tunnel Junction for Magnetic Sensor Peer-reviewed

Takafumi Nakano, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　51　(11)　2015/11

DOI： 10.1109/TMAG.2015.2448723 　

ISSN： 0018-9464

eISSN： 1941-0069
The effect of atomic structure on interface spin-polarization of half-metallic spin valves: Co2MnSi/Ag epitaxial interfaces Peer-reviewed

Zlatko Nedelkoski, Philip J. Hasnip, Ana M. Sanchez, Balati Kuerbanjiang, Edward Higgins, Mikihiko Oogane, Atsufumi Hirohata, Gavin R. Bell, Vlado K. Lazarov

APPLIED PHYSICS LETTERS　107　(21)　2015/11

DOI： 10.1063/1.4936630 　

ISSN： 0003-6951

eISSN： 1077-3118
Negative exchange coupling in Nd2Fe14B(100)/alpha-Fe interface Peer-reviewed

Daisuke Ogawa, Kunihiro Koike, Shigemi Mizukami, Takamichi Miyazaki, Mikihiko Oogane, Yasuo Ando, Hiroaki Kato

APPLIED PHYSICS LETTERS　107　(10)　2015/09

DOI： 10.1063/1.4930829 　

ISSN： 0003-6951

eISSN： 1077-3118
Intrinsic Gilbert damping constant in epitaxial Co2Fe0.4Mn0.6Si Heusler alloys films Peer-reviewed

A.L. Kwilu, M. Oogane, H. Naganuma, M. Sahashi, Y. Ando

J. Appl. Phys.　117　17D140　2015/04
Magnetic damping constant in Co-based full heusler alloy epitaxial films Peer-reviewed

M. Oogane, T. Kubota, H. Naganuma, Y. Ando

JOURNAL OF PHYSICS D-APPLIED PHYSICS　48　(16)　164012　2015/04

DOI： 10.1088/0022-3727/48/16/164012 　

ISSN： 0022-3727

eISSN： 1361-6463
All-optical characterisation of the spintronic Heusler compound Co2Mn0.6Fe0.4Si Peer-reviewed

Thomas Sebastian, Yuki Kawada, Bjoern Obry, Thomas Braecher, Philipp Pirro, Dmytro A. Bozhko, Alexander A. Serga, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Burkard Hillebrands

JOURNAL OF PHYSICS D-APPLIED PHYSICS　48　(16)　164015　2015/04

DOI： 10.1088/0022-3727/48/16/164015 　

ISSN： 0022-3727

eISSN： 1361-6463
Impact of local order and stoichiometry on the ultrafast magnetization dynamics of Heusler compounds Peer-reviewed

Daniel Steil, Oliver Schmitt, Roman Fetzer, Takahide Kubota, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Steven Rodan, Christian G. F. Blum, Benjamin Balke, Sabine Wurmehl, Martin Aeschlimann, Mirko Cinchetti

JOURNAL OF PHYSICS D-APPLIED PHYSICS　48　(16)　164016　2015/04

DOI： 10.1088/0022-3727/48/16/164016 　

ISSN： 0022-3727

eISSN： 1361-6463
Magnetization Dynamics and Damping for L10-FePd Thin Films with Perpendicular Magnetic Anisotropy Peer-reviewed

S. Iihama, M. Khan, H. Naganuma, M. Oogane, T. Miyazaki, S. Mizukami, Y. Ando

J. Magn. Soc. Jpn　39　(2)　57-61　2015/03
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.1501R004 　

ISSN： 1882-2924

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Magnetization dynamics and damping for FePd films were investigated using the all-optical time-resolved magneto-optical Kerr effect. We deposited 16-nm-thick FePd thin films on a single crystal MgO(001) substrate. Both in-plane magnetic anisotropy and perpendicular magnetic anisotropy (PMA) FePd films were fabricated using the magnetron sputtering method at various substrate temperatures T_s. The dependencies of magnetization dynamics on the external magnetic field angle at fixed external magnetic field strengths were analyzed. The effective damping constant, α_eff, for FePd films with PMA exhibited anisotropy, whereas the α_eff for FePd with in-plane magnetic anisotropy did not depend significantly on the field angle. A uniaxial crystalline magnetic anisotropy constant, K_u1, of 11 Merg/cm³ and a minimum for α_eff of 0.007 were observed for film prepared at T_s = 200°C. This α_eff value was much smaller than that for other Fe- and Co-based materials with large PMA such as L1₀-FePt alloy, Co/Pt(Pd) multilayers.
Probing the electronic and spintronic properties of buried interfaces by extremely low energy photoemission spectroscopy Peer-reviewed

Roman Fetzer, Benjamin Stadtmueller, Yusuke Ohdaira, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Tomoyuki Taira, Tetsuya Uemura, Masafumi Yamamoto, Martin Aeschlimann, Mirko Cinchetti

SCIENTIFIC REPORTS　5　8537　2015/02

DOI： 10.1038/srep08537 　

ISSN： 2045-2322
Fabrication of Magnetic Tunnel Junctions with Full Heusler Alloy for Bio-Magnetic Field Sensor

ONO ATSUO, Oogane Mikihiko, Naganuma Hiroshi, Ando Yasuo

Transactions of Japanese Society for Medical and Biological Engineering　53　S187_01-S187_01　2015
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.53.S187_01 　

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Magnetic tunnel junctions (MTJs) have great advantages for the magnetic field sensor applications. However, a significant improvement of tunnel magneto-resistance (TMR) ratio is needed to detect a small bio-magnetic field. In this study, we fabricated MTJs with half-metallic Co₂Fe_0.4Mn_0.6Si(CFMS) Heusler alloy which are expected to increase TMR ratio. The fabricated MTJswere annealed twice to achieve sensor-type TMR curves. Figure shows the 2nd annealing temperature dependence of TMR curves. In MTJ annealed at 200℃, TMR curve showed a linear resistance response, which is required for sensor applications. This work was supported by the S-Innovation program, Japan Science and Technology Agency (JST).
Fabrication and Noise Performance of Magnetic Tunnel Junctions for Detection of Bio-magnetic Field

FUJIWARA KOSUKE, OOGANE MIKIHIKO, KATO DAIKI, JOUNO JUNICHI, NAGANUMA HIROSHI, KATSURADA HIROYUKI, ANDO YASUO

Transactions of Japanese Society for Medical and Biological Engineering　53　S187_03-S187_03　2015
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.53.S187_03 　

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MTJ is a small size device, working in room temperature with low power consumption, and is expected to enable detection of bio-magnetic field without liquid He. For the purpose of practical realization of MTJ bio-magnetic sensor, this study evaluated the signal and noise with various MgO barrier thicknesses in MTJ to reduce 1/f noise in frequency domain. Figures show MgO thickness dependence of signal voltage, noise voltage and S/N ratio measured from 18 Hz, 120 nT_p-p input signal. Both signal and noise voltage increased with increasing MgO thickness. From this relation of signal and noise, maximum 154 S/N ratio was acquired by 2.2 nm MgO thickness.
Electrical Detection of Millimeter-Waves by Magnetic Tunnel Junctions Using Perpendicular Magnetized L1(0)-FePd Free Layer Peer-reviewed

Hiroshi Naganuma, G. Kirn, Yuki Kawada, Nobuhito Inami, Kenzo Hatakeyama, Satoshi Iihama, Khan Mohammed Nazrul Islam, Mikihiko Oogane, Shigemi Mizukami, Yasuo Ando

NANO LETTERS　15　(1)　623-628　2015/01

DOI： 10.1021/nl504114v 　

ISSN： 1530-6984

eISSN： 1530-6992
Preparation of monoclinic 0.9(BiFeO3)-0.1(BiCoO3) epitaxial films on orthorhombic YAlO3 (100) substrates by r.f. magnetron sputtering Peer-reviewed

T. Ichinose, H. Naganuma, K. Mukaiyama, M. Oogane, Y. Ando

JOURNAL OF CRYSTAL GROWTH　409　18-22　2015/01

DOI： 10.1016/j.jcrysgro.2014.09.044 　

ISSN： 0022-0248

eISSN： 1873-5002
Optimization of Domain Wall Oscillations in Magnetic Nanowires Peer-reviewed

A. S. Demiray, H. Naganuma, M. Oogane, Y. Ando

IEEE MAGNETICS LETTERS　6　3700104　2015

DOI： 10.1109/LMAG.2014.2379629 　

ISSN： 1949-307X
Penetration depth of transverse spin current in (001)-oriented epitaxial ferromagnetic films Peer-reviewed

Augustin L. Kwilu, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　368　333-337　2014/11

DOI： 10.1016/j.jmmm.2014.05.043 　

ISSN： 0304-8853

eISSN： 1873-4766
Non-Gilbert-damping Mechanism in a Ferromagnetic Heusler Compound Probed by Nonlinear Spin Dynamics Peer-reviewed

P. Pirro, T. Sebastian, T. Braecher, A. A. Serga, T. Kubota, H. Naganuma, M. Oogane, Y. Ando, B. Hillebrands

PHYSICAL REVIEW LETTERS　113　(22)　227601　2014/11

DOI： 10.1103/PhysRevLett.113.227601 　

ISSN： 0031-9007

eISSN： 1079-7114
Low precessional damping observed for L1(0)-ordered FePd epitaxial thin films with large perpendicular magnetic anisotropy Peer-reviewed

S. Iihama, A. Sakuma, H. Naganuma, M. Oogane, T. Miyazaki, S. Mizukami, Y. Ando

APPLIED PHYSICS LETTERS　105　(14)　142403　2014/10

DOI： 10.1063/1.4897547 　

ISSN： 0003-6951

eISSN： 1077-3118
Present and perspective of bio-magnetic measurement using ferromagnetic tunnel junctions Peer-reviewed

Y. Ando, T. Nishikawa, K. Fujiwara, M. Oogane, D. Kato, H. Naganuma

Transactions of Japanese Society for Medical and Biological Engineering　52　33-OS-34　2014/08/17
Publisher: Japan Soc. of Med. Electronics and Biol. Engineering
DOI： 10.11239/jsmbe.52.OS-33 　

ISSN： 1347-443X 1881-4379
Correlations between atomic structure and giant magnetoresistance ratio in Co-2(Fe, Mn) Si spin valves Peer-reviewed

L. Lari, K. Yoshida, P. L. Galindo, J. Sato, J. Sizeland, D. Gilks, G. M. Uddin, Z. Nedelkoski, P. J. Hasnip, A. Hirohata, M. Oogane, Y. Ando, V. K. Lazarov

JOURNAL OF PHYSICS D-APPLIED PHYSICS　47　(32)　322003　2014/08

DOI： 10.1088/0022-3727/47/32/322003 　

ISSN： 0022-3727

eISSN： 1361-6463
Mode change of vortex core oscillation induced by large direct current in 120 nm sized current perpendicular-to-plane giant magnetoresistance devices with a perpendicular polarizer Peer-reviewed

Yuki Kawada, Hiroshi Naganuma, Ahmet Serdar Demiray, Mikihiko Oogane, Yasuo Ando

APPLIED PHYSICS LETTERS　105　(5)　052407　2014/08

DOI： 10.1063/1.4892077 　

ISSN： 0003-6951

eISSN： 1077-3118
Preparation of a heteroepitaxial LaxSryMnzO3/BiFeO3 bilayer by r.f. magnetron sputtering with various oxygen gas flow ratios Peer-reviewed

H. Naganuma, T. Ichinose, H. A. Begum, S. Sato, X. F. Han, T. Miyazaki, In-T. Bae, M. Oogane, Y. Ando

AIP ADVANCES　4　(8)　087133　2014/08

DOI： 10.1063/1.4893998 　

ISSN： 2158-3226
Ultrafast magnetization dynamics in Co-based Heusler compounds with tuned chemical ordering Peer-reviewed

D. Steil, O. Schmitt, R. Fetzer, T. Kubota, H. Naganuma, M. Oogane, Y. Ando, A. K. Suszka, O. Idigoras, G. Wolf, B. Hillebrands, A. Berger, M. Aeschlimann, M. Cinchetti

NEW JOURNAL OF PHYSICS　16　063068　2014/06

DOI： 10.1088/1367-2630/16/6/063068 　

ISSN： 1367-2630
Static and dynamic magnetic properties of cubic Mn-Co-Ga Heusler films Peer-reviewed

A. S. Demiray, T. Kubota, S. Iihama, S. Mizukami, T. Miyazaki, H. Naganuma, M. Oogane, Y. Ando

JOURNAL OF APPLIED PHYSICS　115　(17)　2014/05

DOI： 10.1063/1.4864250 　

ISSN： 0021-8979

eISSN： 1089-7550
Tunnel magnetoresistance effect using perpendicularly magnetized tetragonal and cubic Mn-Co-Ga Heusler alloy electrode Peer-reviewed

T. Kubota, S. Mizukami, Q. L. Ma, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF APPLIED PHYSICS　115　(17)　2014/05

DOI： 10.1063/1.4855016 　

ISSN： 0021-8979

eISSN： 1089-7550
Spin-dependent transport behavior in C-60 and Alq(3) based spin valves with a magnetite electrode (invited) Peer-reviewed

Xianmin Zhang, Shigemi Mizukami, Qinli Ma, Takahide Kubota, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　115　(17)　172608　2014/05

DOI： 10.1063/1.4870154 　

ISSN： 0021-8979

eISSN： 1089-7550
Gilbert damping constants of Ta/CoFeB/MgO(Ta) thin films measured by optical detection of precessional magnetization dynamics Peer-reviewed

Satoshi Iihama, Shigemi Mizukami, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

PHYSICAL REVIEW B　89　(17)　174416　2014/05

DOI： 10.1103/PhysRevB.89.174416 　

ISSN： 1098-0121

eISSN： 1550-235X
Half-metal CPP GMR sensor for magnetic recording Peer-reviewed

Z. Diao, M. Chapline, Y. Zheng, C. Kaiser, A. Ghosh Roy, C. J. Chien, C. Shang, Y. Ding, C. Yang, D. Mauri, Q. Leng, M. Pakala, M. Oogane, Y. Ando

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　356　73-81　2014/04

DOI： 10.1016/j.jmmm.2013.12.050 　

ISSN： 0304-8853

eISSN： 1873-4766
B2 Atomic Disorder in Co₂Fe_xMn_1-xSi Heusler Alloys Peer-reviewed

P.J. Hasnip, C. H. Loach, J. H. Smith, M. I. J. Probert, D. Gilks, J. Sizeland, K. Yoshida, M. Oogane, A. Hirohata, V. K. Lazarov

Journal of the Magnetics Society of Japan　38　50-55　2014/03/20

DOI： 10.3379/msjmag.1402R010 　
The Effect of Cobalt-Sublattice Disorder on Spin Polarisation in Co2FexMn1-xSi Heusler Alloys Peer-reviewed

Philip J. Hasnip, Christian H. Loach, Joseph H. Smith, Matthew I. J. Probert, Daniel Gilks, James Sizeland, Leonardo Lari, James Sagar, Kenta Yoshida, Mikihiko Oogane, Atsufumi Hirohata, Vlado K. Lazarov

MATERIALS　7　(3)　1473-1482　2014/03

DOI： 10.3390/ma7031473 　

ISSN： 1996-1944

eISSN： 1996-1944
Development of Integrated Magnetic Tunnel Junctions for Detection of Bio-magnetic Field

Nishikawa Takuo, Oogane Mikihiko, Fujiwara Kousuke, Kato Daiki, Naganuma Hiroshi, Ando Yasuo

BME　52　O-503-O-503　2014
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.52.O-503 　

ISSN： 1347-443X

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Although the biomagnetic field is useful to observe an organic activity and the superconducting quantum interference device (SQUID) is used to detect at the moment, there is a problem of needing a liquid helium in order to operate this SQUID. This research focuses attention on the ferromagnetic tunnel junction (MTJ) device which is operable in a room temperature, and aims at the reduction of the elements for using this MTJ device as a biomagnetic field sensor and the reduction of the circuit system noise.
Fabrication of Magnetic Tunnel Junctions with Amorphous CoFeSiB for the Bio-magnetic Field Sensor Devices

Kato Daiki, Oogane Mikihiko, Fujiwara Kosuke, Nishikawa Takuo, Naganuma Hiroshi, Ando Yasuo

BME　52　O-504-O-504　2014
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.52.O-504 　

ISSN： 1347-443X

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In magnetic tunnel junctions (MTJs), the resistance changes by external magnetic field through tunnel magnetoresistance (TMR) effect and MTJs can be applied to magnetic field sensors. To detect a small bio-magnetic field, we have to develop MTJs with high sensitivity (=TMR/2H_k, H_k: magnetic anisotropy field) of more than 100%/Oe, which is two digit larger than that of actual devices. In this work, MTJs with a low H_k CoFeSiB amorphous electrode was fabricated to realize such a highly sensitive magnetic sensor. After optimizing the preparation condition of CoFeSiB, a very high sensitivity of 40%/Oe was obtained. The result came much closer to our goal.
Dependence of Magnetic Damping on Temperature and Crystal Orientation in Epitaxial Fe4N Thin Films Peer-reviewed

S. Isogami, M. Tsunoda, M. Oogane, A. Sakuma, M. Takahashi

Journal of the Magnetics Society of Japan　38　(4)　162-168　2014
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.1406R001 　 10.3379/msjmag.1406r001 　

ISSN： 1882-2924

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In-plane and out-of-plane ferromagnetic resonance (FMR) were used to investigate the intrinsic magnetic damping constant (α) in epitaxial Fe₄N thin films deposited on MgO substrates. The dependence of α on temperature was evaluated from room temperature (RT) to 4 K. The external magnetic field (H) of FMR was applied in two directions, i.e., [100] and [110], of the Fe₄N lattice. Anisotropic α was observed from RT to 4 K. Moreover, the α for H // [100] exceeded the α for H // [110] at 180 K. Numerical calculations of α for bulk Fe₄N revealed the same behavior as that in the experiments. The temperature dependence of anisotropic α was explained by the changes in the electronic band structure depending on the directions of magnetization.
Fabrication of Integrated Magnetic Tunnel Junctions for Detection of Bio-magnetic Field Peer-reviewed

K. Fujiwara, M. Oogane, D. Kato, T. Nishikawa, H. Naganuma, Y. Ando

Transactions of Japanese Society for Medical and Biological Engineering　52　O-505-505-O-506　2014
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.52.O-505 　

ISSN： 1347-443X

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Since MTJ sensor is an element of room temperature operation, low power consumption, low cost and small device size, thus it is expectable to spread widely the medical diagnostics and basic research using bio-magnetic fields. In this study, in order to reduce 1/f noise, 100x100 MTJ sensor arrays were fabricated. Figure shows the system of imperceptible magnetic filed detection. The magnetic field was generated with the one turn coil, using the sine wave of 123 Hz. The result is shown in figure. In this study, the detection of a magnetic field of 0.29 nT was demonstrated with fabricated 100x100 MTJ sensor array.
Spin and symmetry properties of the buried Co2MnSi/MgO interface Peer-reviewed

R. Fetzer, Y. Ohdaira, H. Naganuma, M. Oogane, Y. Ando, T. Taira, T. Uemura, M. Yamamoto, M. Aeschlimann, M. Cinchetti

58th Annual Conf. on Magnetism and Magnetic Materials, Abstracts　624 (GB-14)　2013/11
Fabrication of Magnetic Tunnel Junctions with Amorphous CoFeSiB Ferromagnetic Electrode for Magnetic Field Sensor Devices Peer-reviewed

Daiki Kato, Mikihiko Oogane, Kosuke Fujiwara, Takuo Nishikawa, Hiroshi Naganuma, Yasuo Ando

APPLIED PHYSICS EXPRESS　6　(10)　2013/10

DOI： 10.7567/APEX.6.103004 　

ISSN： 1882-0778

eISSN： 1882-0786
Tunneling magnetoresistance effect in MnGa based perpendicular magnetic tunnel junction with Fe/Co interlayer Peer-reviewed

Qinli Ma, Shigemi Mizukami, Takahide Kubota, Xianmin Zhang, Atsushi Sugihara, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　114　(16)　2013/10

DOI： 10.1063/1.4828483 　

ISSN： 0021-8979

eISSN： 1089-7550
The role of structure on magneto-transport properties of Heusler Co2MnSi films deposited on MgO(001) Peer-reviewed

N. Tal, D. Mogilyanski, A. Kovacs, H. Naganuma, S. Tsunegi, M. Oogane, Y. Ando, A. Kohn

JOURNAL OF APPLIED PHYSICS　114　(16)　2013/10

DOI： 10.1063/1.4826908 　

ISSN： 0021-8979

eISSN： 1089-7550
Evaluation of interlayer exchange coupling in α-Fe(100)/Nd2Fe14B(001) Films Peer-reviewed

D. Ogawa, K. Koike, S. Mizukami, T. Miyazaki, M. Oogane, Y. Ando, H. Kato

J. Korean Phys. Soc.　63　(2)　0-0　2013/07
Effect of Annealing Temperature on Structure and Magnetic Properties of L1(0)-FePd/CoFeB Bilayer Peer-reviewed

M. N. I. Khan, H. Naganuma, N. Inami, M. Oogane, Y. Ando

IEEE TRANSACTIONS ON MAGNETICS　49　(7)　4409-4412　2013/07

DOI： 10.1109/TMAG.2013.2251612 　

ISSN： 0018-9464

eISSN： 1941-0069
Observation of Precessional Magnetization Dynamics in L1(0)-FePt Thin Films with Different L1(0) Order Parameter Values Peer-reviewed

Satoshi Iihama, Shigemi Mizukami, Nobuhito Inami, Takashi Hiratsuka, Gukcheon Kim, Hiroshi Naganuma, Mikihiko Oogane, Terunobu Miyazaki, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　52　(7)　2013/07

DOI： 10.7567/JJAP.52.073002 　

ISSN： 0021-4922

eISSN： 1347-4065
The Enhancement of Magnetic Damping in Fe4N Films with Increasing Thickness Peer-reviewed

Shinji Isogami, Masakiyo Tsunoda, Mikihiko Oogane, Akimasa Sakuma, Migaku Takahashi

JAPANESE JOURNAL OF APPLIED PHYSICS　52　(7)　2013/07

DOI： 10.7567/JJAP.52.073001 　

ISSN： 0021-4922
Fabrication of L1(0)-Ordered MnAl Films for Observation of Tunnel Magnetoresistance Effect Peer-reviewed

Haruaki Saruyama, Mikihiko Oogane, Yuta Kurimoto, Hiroshi Naganuma, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　52　(6)　2013/06

DOI： 10.7567/JJAP.52.063003 　

ISSN： 0021-4922

eISSN： 1347-4065
Enhancement of Spin Pumping Efficiency in Fe4N/Pt Bilayer Films Peer-reviewed

Shinji Isogami, Masakiyo Tsunoda, Mikihiko Oogane, Akimasa Sakuma, Migaku Takahasi

APPLIED PHYSICS EXPRESS　6　(6)　2013/06

DOI： 10.7567/APEX.6.063004 　

ISSN： 1882-0778
Interface tailoring effect on magnetic properties and their utilization in MnGa-based perpendicular magnetic tunnel junctions Peer-reviewed

Q. L. Ma, T. Kubota, S. Mizukami, X. M. Zhang, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

PHYSICAL REVIEW B　87　(18)　2013/05

DOI： 10.1103/PhysRevB.87.184426 　

ISSN： 1098-0121
Magnetic tunnel junctions of perpendicularly magnetized L1(0)-MnGa/Fe/MgO/CoFe structures: Fe-layer-thickness dependences of magnetoresistance effect and tunnelling conductance spectra Peer-reviewed

T. Kubota, Q. L. Ma, S. Mizukami, X. M. Zhang, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF PHYSICS D-APPLIED PHYSICS　46　(15)　2013/04

DOI： 10.1088/0022-3727/46/15/155001 　

ISSN： 0022-3727

eISSN： 1361-6463
Detection of sub-nano-tesla magnetic field by integrated magnetic tunnel junctions with bottom synthetic antiferro-coupled free layer Peer-reviewed

Kosuke Fujiwara, Mikihiko Oogane, Takuo Nishikawa, Hiroshi Naganuma, Yasuo Ando

Japanese Journal of Applied Physics　52　(4)　2013/04

DOI： 10.7567/JJAP.52.04CM07 　

ISSN： 0021-4922 1347-4065
Nonlinear Emission of Spin-Wave Caustics from an Edge Mode of a Microstructured Co2Mn0.6Fe0.4Si Waveguide Peer-reviewed

T. Sebastian, T. Braecher, P. Pirro, A. A. Serga, B. Hillebrands, T. Kubota, H. Naganuma, M. Oogane, Y. Ando

PHYSICAL REVIEW LETTERS　110　(6)　2013/02

DOI： 10.1103/PhysRevLett.110.067201 　

ISSN： 0031-9007
Tunnel magnetoresistance effect in tunnel junctions with Co2MnSi heusler alloy electrode and MgO barrier Peer-reviewed

Yasuo Ando, Sumito Tsunegi, Mikihiko Oogane, Hiroshi Naganuma, Koki Takanashi

Spintronics: From Materials to Devices　355-366　2013/01/01
Publisher: Springer Netherlands
DOI： 10.1007/978-90-481-3832-6_17 　
Evaluation of interlayer exchange coupling in alpha-Fe(100)/Nd2Fel4B(001) films Peer-reviewed

D. Ogawa, K. Koike, H. Kato, S. Mizukami, T. Miyazaki, M. Oogane, Y. Ando

Journal of the Korean Physical Society　63　(3)　489-492　2013

DOI： 10.3938/jkps.63.489 　
Observation of a large spin-dependent transport length in organic Spin valves at room temperature Peer-reviewed

Xianmin Zhang, Shigemi Mizukami, Takahide Kubota, Qinli Ma, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

Nature Communications　4　2013

DOI： 10.1038/ncomms2423 　

ISSN： 2041-1723
Magnetoresistance enhancement in MnxGa 100 - X/MgO/CoFeB perpendicular magnetic tunnel junctions by using CoFeB interlayer Peer-reviewed

Q. L. Ma, T. Kubota, S. Mizukami, X. M. Zhang, M. Oogane, H. Naganuma, Y. Ando, T. Miyazaki

IEEE Transactions on Magnetics　49　(7)　4339-4342　2013

DOI： 10.1109/TMAG.2013.2242861 　

ISSN： 0018-9464
Magnetic Properties of Single Crystalline Co2MnAl Heusler Alloy Thin Films Peer-reviewed

Yilgin Resul, Sakuraba Yuya, Oogane Mikihiko, Ando Yasuo, Miyazaki Terunobu

JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM　25　(8)　2659-2663　2012/12

DOI： 10.1007/s10948-011-1238-x 　

ISSN： 1557-1939
EVALUATION OF EXCHANGE COUPLING IN Nd2Fe14B/α-Fe INTERFACES

D. Ogawa, K. Koike, S. Mizukami, T. Miyazaki, M. Oogane, Y. Ando, H. Kato

Proceedings on 21st Workshop on Rare-Earth Permanent Magnets and their Applications (REPM'12)　2012/09/02
Enhancement of magnetoresistance using CoFe/Ru/CoFe synthetic ferrimagnetic pinned layer in BiFeO3 based spin-valves Peer-reviewed

Hiroshi Naganuma, In-Tae Bae, Takamichi Miyazaki, Miho Kubota, Nobuhito Inami, Yuki Kawada, Mikihiko Oogane, Shigemi Mizukami, X. F. Han, Yasuo Ando

APPLIED PHYSICS LETTERS　101　(7)　2012/08

DOI： 10.1063/1.4745504 　

ISSN： 0003-6951
Magnetoresistance effect in L1(0)-MnGa/MgO/CoFeB perpendicular magnetic tunnel junctions with Co interlayer Peer-reviewed

Q. L. Ma, T. Kubota, S. Mizukami, X. M. Zhang, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

APPLIED PHYSICS LETTERS　101　(3)　2012/07

DOI： 10.1063/1.4737000 　

ISSN： 0003-6951
Nd2Fe14B/α-Fe界面における交換結合の評価

小川大介, 小池邦博, 水上成美, 大兼幹彦, 安藤康夫, 宮崎孝道, 加藤宏朗

信学技報　2012/06/14
Annealing Temperature and Co Layer Thickness Dependence of Magnetoresistance Effect for -MnGa/Co/MgO/CoFeB Perpendicular Magnetic Tunnel Junctions Peer-reviewed

Q. L. Ma, Takahide Kubota, Shigemi Mizukami, X. M. Zhang, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

IEEE Transactions on Magnetics　48　2808-2811　2012/04/16

DOI： 10.1109/TMAG.2012.2196420 　
Fabrication of L1(0)-MnAl perpendicularly magnetized thin films for perpendicular magnetic tunnel junctions Peer-reviewed

Masaki Hosoda, Mikihiko Oogane, Miho Kubota, Takahide Kubota, Haruaki Saruyama, Satoshi Iihama, Hiroshi Naganuma, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　111　(7)　2012/04

DOI： 10.1063/1.3676428 　

ISSN： 0021-8979

eISSN： 1089-7550
Dependence of spin-transfer switching characteristics in magnetic tunnel junctions with synthetic free layers on coupling strength Peer-reviewed

Masayuki Nishimura, Mikihiko Oogane, Hiroshi Naganuma, Nobuhito Inami, Tadashi Morita, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　111　(7)　2012/04

DOI： 10.1063/1.3672240 　

ISSN： 0021-8979

eISSN： 1089-7550
Promotion of L1(0) ordering of FePd films with amorphous CoFeB thin interlayer Peer-reviewed

M. N. I. Khan, N. Inami, H. Naganuma, Y. Ohdaira, M. Oogane, Y. Ando

JOURNAL OF APPLIED PHYSICS　111　(7)　2012/04

DOI： 10.1063/1.3673409 　

ISSN： 0021-8979

eISSN： 1089-7550
Large change of perpendicular magnetic anisotropy in Cobalt ultrathin film induced by varying capping layers Peer-reviewed

Xianmin Zhang, Shigemi Mizukami, Takahide Kubota, Qinli Ma, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　111　(7)　2012/04

DOI： 10.1063/1.3676240 　

ISSN： 0021-8979

eISSN： 1089-7550
Fabrication of magnetic tunnel junctions with a bottom synthetic antiferro-coupled free layers for high sensitive magnetic field sensor devices Peer-reviewed

Kosuke Fujiwara, Mikihiko Oogane, Saeko Yokota, Takuo Nishikawa, Hiroshi Naganuma, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　111　(7)　2012/04

DOI： 10.1063/1.3677266 　

ISSN： 0021-8979

eISSN： 1089-7550
Dependence of Tunnel Magnetoresistance Effect on Fe Thickness of Perpendicularly Magnetized L1(0)-Mn62Ga38/Fe/MgO/CoFe Junctions Peer-reviewed

Takahide Kubota, Qinli Ma, Shigemi Mizukami, Xianmin Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS EXPRESS　5　(4)　2012/04

DOI： 10.1143/APEX.5.043003 　

ISSN： 1882-0778

eISSN： 1882-0786
Low-damping spin-wave propagation in a micro-structured Co2Mn0.6Fe0.4Si Heusler waveguide Peer-reviewed

T. Sebastian, Y. Ohdaira, T. Kubota, P. Pirro, T. Braecher, K. Vogt, A. A. Serga, H. Naganuma, M. Oogane, Y. Ando, B. Hillebrands

APPLIED PHYSICS LETTERS　100　(11)　2012/03

DOI： 10.1063/1.3693391 　

ISSN： 0003-6951
Spin-RAM for Normally-Off Computer Peer-reviewed

K.Ando, K.Yakushiji, H.Kubota, A.Fukushima, S.Yuasa, T.Kai, T.Kishi, N.Shimomura, H.Aikawa, M.Yoshikawa, T.Nagase, K.Nishiyama, E.Kitagawa, T.Daibou, M.Amano, S.Takahashi, M.Nakayama, S.Ikegawa, M.Nagamine, J.Ozeki, D.Watanabe, H.Yoda, T.Nozaki, Y.Suzuki, M.Oogane, S.Mizukami, Y.Ando, T.Miyazaki, Y.Nakatani

Conference Publications NVMTSプロシーディング　1-6　2012/01

DOI： 10.1109/NVMTS.2011.6137104 　
Evaluation of Exchange Coupling in .ALPHA.-Fe(100)/Nd2Fe14B(001) Interface

Ogawa D., Koike K., Mizukami S., Oogane M., Ando Y., Miyazaki T., Kato H.

Transactions of the Magnetics Society of Japan　36　(1)　5-12　2012
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.1201R001 　

ISSN： 1882-2924

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Magnetic bilayer films with an interface of α-Fe(100) and Nd₂Fe₁₄B(001) planes were fabricated in order to evaluate the exchange-coupling constant, which was recently reported to depend on the Miller indices of the interface planes. The epitaxial growth of both α-Fe and Nd₂Fe₁₄B layers was confirmed with the epitaxial relation of MgO(100)[100] || α-Fe(100)[110] || Nd₂Fe₁₄B(001) [110], according to the X-ray pole-figure measurements. FMR experiments on this film were performed by using a Q-band microwave apparatus. We observed a significant shift of α-Fe resonance field from H_r = 5.24 kOe to H_r = 4.41 kOe in a bilayer film sputtered at T_S^NFB = 650°C compared to a reference film without an Nd₂Fe₁₄B layer. This lower shift suggests the existence of an internal field due to the positive exchange coupling between α-Fe and Nd₂Fe₁₄B phases. The magnitude of the exchange-coupling constant was estimated to be in the range between 6.5 and 11 erg/cm² for the bilayer film sputtered at T_S^NFB = 650°C.
Composition dependence of magnetic properties in perpendicularly magnetized epitaxial thin films of Mn-Ga alloys Peer-reviewed

S. Mizukami, T. Kubota, F. Wu, X. Zhang, T. Miyazaki, H. Naganuma, M. Oogane, A. Sakuma, Y. Ando

PHYSICAL REVIEW B　85　(1)　2012/01

DOI： 10.1103/PhysRevB.85.014416 　

ISSN： 1098-0121
The magnetic and structural properties of Co2MnSi Heusler alloy thin films on the orientation of Ge substrate Peer-reviewed

M. A. I. Nahid, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

Phys. Status Solidi A　208　675-378　2011/12/06

DOI： 10.1002/pssa.201026569 　
Composition dependence of magnetoresistance effect and its annealing endurance in tunnel junctions having Mn-Ga electrode with high perpendicular magnetic anisotropy Peer-reviewed

Takahide Kubota, Masaaki Araidai, Shigemi Mizukami, Xianmin Zhang, Qinli Ma, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Masaru Tsukada, Terunobu Miyazaki

APPLIED PHYSICS LETTERS　99　(19)　2011/11

DOI： 10.1063/1.3659484 　

ISSN： 0003-6951

eISSN： 1077-3118
Large Magnetoresistance Effect in Epitaxial Co2Fe0.4Mn0.6Si/Ag/Co2Fe0.4Mn0.6Si Devices Peer-reviewed

Jo Sato, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

APPLIED PHYSICS EXPRESS　4　(11)　2011/11

DOI： 10.1143/APEX.4.113005 　

ISSN： 1882-0778

eISSN： 1882-0786
Interface effects on perpendicular magnetic anisotropy for molecular-capped cobalt ultrathin films Peer-reviewed

Xianmin Zhang, Shigemi Mizukami, Takahide Kubota, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS LETTERS　99　(16)　2011/10

DOI： 10.1063/1.3651766 　

ISSN： 0003-6951
Influence of Pt Doping on Gilbert Damping in Permalloy Films and Comparison with the Perpendicularly Magnetized Alloy Films Peer-reviewed

Shigemi Mizukami, Takahide Kubota, Xianmin Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS　50　(10)　2011/10

DOI： 10.1143/JJAP.50.103003 　

ISSN： 0021-4922
Time-Resolved Kerr Effect in Very Thin Films of CoCrPt Alloys Peer-reviewed

Shigemi Mizukami, Daisuke Watanabe, Takahide Kubota, X. Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, T. Miyazaki

IEEE Transaction on Magnetics　47　(10)　3897-38900　2011/09/23

DOI： 10.1109/TMAG.2011.2154357 　
Spin Transport in Co/Al2O3 Alq3 Co Organic Spin Valve Peer-reviewed

Xianmin Zhang, Shigemi Mizukami, Takahide Kubota???, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

IEEE TRANSACTIONS ON MAGNETICS　47　(10)　2649-2651　2011/09
Spin transistor using magnetic tunnel junctions with half-metallic Co2MnSi Heusler alloy electrodes Peer-reviewed

Y. Ohdaira, M. Oogane, H. Naganuma, Y. Ando

APPLIED PHYSICS LETTERS　99　(13)　2011/09

DOI： 10.1063/1.3645637 　

ISSN： 0003-6951

eISSN： 1077-3118
Tunnel magnetoresistance effect and magnetic damping in half-metallic Heusler alloys Invited Peer-reviewed

M. Oogane, S. Mizukami

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES　369　(1948)　3037-3053　2011/08

DOI： 10.1098/rsta.2011.0011 　

ISSN： 1364-503X

eISSN： 1471-2962
Fabrication of MgO-based magnetic tunnel junctions for subnanosecond spin transfer switching Peer-reviewed

Tatsuya Aoki, Yasuo Ando, Mikihiko Oogane, Hiroshi Naganuma

Journal of Physics: conference serise　266　012086　2011/07

DOI： 10.1088/1742-6596/266/1/012086 　
Effect of metallic Mg insertion on the magnetoresistance effect in MgO-based tunnel junctions using D0(22)-Mn3-delta Ga perpendicularly magnetized spin polarizer Peer-reviewed

Takahide Kubota, Shigemi Mizukami, Daisuke Watanabe, Feng Wu, Xianmin Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　110　(1)　2011/07

DOI： 10.1063/1.3603034 　

ISSN： 0021-8979
Fabrication of Multiferroic Co-Substituted BiFeO3 Epitaxial Films on SrTiO3 (100) Substrates by Radio Frequency Magnetron Sputtering Peer-reviewed

Husne Ara Begum, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

Materials　4　1087-1095　2011/06/09

DOI： 10.3390/ma4061087 　
The effect of film and interface structure on the transport properties of Heusler based current-perpendicular-to-plane spin valves Peer-reviewed

V. K. Lazarov, K. Yoshida, J. Sato, P. J. Hasnip, M. Oogane, A. Hirohata, Y. Ando

APPLIED PHYSICS LETTERS　98　(24)　2011/06

DOI： 10.1063/1.3600792 　

ISSN： 0003-6951

eISSN： 1077-3118
Magnetoresistance Effect in Tunnel Junctions with Perpendicularly Magnetized D0(22)-Mn3-delta Ga Electrode and MgO Barrier Peer-reviewed

Takahide Kubota, Yoshio Miura, Daisuke Watanabe, Shigemi Mizukami, Feng Wu, Hiroshi Naganuma, Xianmin Zhang, Mikihiko Oogane, Masafumi Shirai, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS EXPRESS　4　(4)　2011/04

DOI： 10.1143/APEX.4.043002 　

ISSN： 1882-0778
Exchange biases of Co, Py, Co40Fe40B20, Co75Fe25, and Co50Fe50 on epitaxial BiFeO3 films prepared by chemical solution deposition Peer-reviewed

Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　109　(7)　2011/04

DOI： 10.1063/1.3563061 　

ISSN： 0021-8979
Long-Lived Ultrafast Spin Precession in Manganese Alloys Films with a Large Perpendicular Magnetic Anisotropy Peer-reviewed

S. Mizukami, F. Wu, A. Sakuma, J. Walowski, D. Watanabe, T. Kubota, X. Zhang, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

PHYSICAL REVIEW LETTERS　106　(11)　2011/03

DOI： 10.1103/PhysRevLett.106.117201 　

ISSN： 0031-9007
The effect of inserting thin Co2MnAl layer into the Co2MnSi/MgO interface on tunnel magnetoresistance effect Peer-reviewed

E. Ozawa, S. Tsunegi, M. Oogane, H. Naganuma, Y. Ando

Journal ofPhysics:ConferenceSeries　266　012104-1-012104-4　2011/01/28

DOI： 10.1088/1742-6596/266/1/012104 　
Magnetoresistance Effect in Co2MnSi/semimetallic-Fe2VAl/CoFe Junctions Peer-reviewed

T Kubota, M Oogane, S Mizukami, H Naganuma, Y Ando, T Miyazaki

Journal ofPhysics:ConferenceSeries　266　012096-1-012096-5　2011/01/28

DOI： 10.1088/1742-6596/266/1/012096 　
Influence of composition on structure and magnetic properties of epitaxial Mn-Ga films Peer-reviewed

F Wu, S Mizukami, D Watanabe, H Naganuma, M Oogane, Y Ando, T Miyazaki

Journal of Physics: Conference Series　266　012112-1-012112-5　2011/01/28

DOI： 10.1088/1742-6596/266/1/012112 　
Large Tunnel Magnetoresistance of 1056% at Room Temperature in MgO Based Double Barrier Magnetic Tunnel Junction (Retraction of vol 2, 083002, 2009) Peer-reviewed

Hiroshi Naganuma, Lixian Jiang, Mikihiko Oogane, Yasuo Ando

APPLIED PHYSICS EXPRESS　4　(1)　019201-019201　2011/01

DOI： 10.1143/APEX.4.019201 　

ISSN： 1882-0778
Laser-induced fast magnetization precession and Gilbert damping for CoCrPt alloy thin films with perpendicular magnetic anisotropy Peer-reviewed

Shigemi Mizukami, Daisuke Watanabe, Takahide Kubota, Xianmin Zhang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

Applied physics express　3　123001-1-123001-3　2011
Gilbert Damping in Ni/Co Multilayer Films Exhibiting Large Perpendicular Anisotropy Peer-reviewed

Shigemi Mizukami, Xianmin Zhang, Takahide Kubota, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS EXPRESS　4　(1)　2011/01

DOI： 10.1143/APEX.4.013005 　

ISSN： 1882-0778
Fabrication of Magnetic Tunnel Junctions with a Synthetic Ferrimagnetic Free Layer for Magnetic Field Sensor Applications Peer-reviewed

Kousuke Fujiwara, Mikihiko Oogane, Futoyoshi Kou, Daisuke Watanabe, Hiroshi Naganuma, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　50　(1)　2011/01

DOI： 10.1143/JJAP.50.013001 　

ISSN： 0021-4922
Fast magnetization precession observed in L1(0)-FePt epitaxial thin film Peer-reviewed

S. Mizukami, S. Iihama, N. Inami, T. Hiratsuka, G. Kim, H. Naganuma, M. Oogane, Y. Ando

APPLIED PHYSICS LETTERS　98　(5)　2011/01

DOI： 10.1063/1.3549704 　

ISSN： 0003-6951

eISSN： 1077-3118
Band-Structure-Dependent Demagnetization in the Heusler Alloy Co2Mn1-xFexSi Peer-reviewed

Daniel Steil, Sabine Alebrand, Tobias Roth, Michael Krauss, Takahide Kubota, Mikihiko Oogane, Yasuo Ando, Hans Christian Schneider, Martin Aeschlimann, Mirko Cinchetti

PHYSICAL REVIEW LETTERS　105　(21)　2010/11

DOI： 10.1103/PhysRevLett.105.217202 　

ISSN： 0031-9007
Ferromagnetic resonance investigation of exchange coupling in Nd2Fe14B/α-Fe interfaces

D. Ogawa, K. Koike, T. Miyazaki, S. Mizukami, T. Akiya, M. Oogane, Y. Ando, H. Kato

Proc. on the 21th International Workshop on Rare-earth Permanent Magnets and their Applications　2010/08/28
Gilbert magnetic damping constant of epitaxially grown Co-based Heusler alloy thin films Peer-reviewed

M. Oogane, T. Kubota, Y. Kota, S. Mizukami, H. Naganuma, A. Sakuma, Y. Ando

APPLIED PHYSICS LETTERS　96　(25)　2010/06

DOI： 10.1063/1.3456378 　

ISSN： 0003-6951

eISSN： 1077-3118
Structural and Magnetic Properties of Perpendicular Magnetized Mn2.5Ga Epitaxial Films Peer-reviewed

F. Wu, S. Mizukami, D. Watanabe, E. P. Sajitha, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

IEEE TRANSACTIONS ON MAGNETICS　46　(6)　1863-1865　2010/06

DOI： 10.1109/TMAG.2010.2045108 　

ISSN： 0018-9464
Magnetization Dynamics in CoFeB Buffered Perpendicularly Magnetized Co/Pd Multilayer Peer-reviewed

E. P. Sajitha, Jakob Walowski, D. Watanabe, S. Mizukami, Feng Wu, Hiroshi Naganuma, Mikihito Oogane, Yasuo Ando, T. Miyazaki

IEEE TRANSACTIONS ON MAGNETICS　46　(6)　2056-2059　2010/06

DOI： 10.1109/TMAG.2009.2038929 　

ISSN： 0018-9464
The Effect of Doping Concentration of Si on the Nature of Barrier of Co2MnSi/MgO/n-Si Junctions Peer-reviewed

M. A. I. Nahid, M. Oogane, H. Naganuma, Y. Ando

IEEE TRANSACTIONS ON MAGNETICS　46　(6)　1637-1640　2010/06

DOI： 10.1109/TMAG.2010.2043223 　

ISSN： 0018-9464
Fabrication of perpendicularly magnetized magnetic tunnel junctions with [formula omitted] hybrid electrode Peer-reviewed

T. Hiratsuka, G. Kim, Y. Sakuraba, T. Kubota, K. Kodama, N. Inami, H. Naganuma, M. Oogane, T. Nakamura, K. Takanashi, Y. Ando

Journal of Applied Physics　107　(9)　2010/05/01

DOI： 10.1063/1.3358239 　

ISSN： 1089-7550 0021-8979

eISSN： 1089-7550
Fabrication of perpendicularly magnetized magnetic tunnel junctions with L1(0)-CoPt/Co2MnSi hybrid electrode Peer-reviewed

T. Hiratsuka, G. Kim, Y. Sakuraba, T. Kubota, K. Kodama, N. Inami, H. Naganuma, M. Oogane, T. Nakamura, K. Takanashi, Y. Ando

JOURNAL OF APPLIED PHYSICS　107　(9)　2010/05

DOI： 10.1063/1.3358239 　

ISSN： 0021-8979

eISSN： 1089-7550
High efficient spin transfer torque writing on perpendicular magnetic tunnel junctions for high density MRAMs Peer-reviewed

Tatsuya Kishi, Toshihiko Nagase, Masatoshi Yoshikawa, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Minoru Amano, Naoharu Shimomura, Shigeki Takahashi, Tadashi Kai, Masahiko Nakayama, Hisanori Aikawa, Sumio Ikegawa, Makoto Nagamine, Junichi Ozeki, Shigemi Mizukami, Mikihiko Oogane, Yasuo Ando, Shinji Yuasa, Kei Yakushiji, Hitoshi Kubota, Yoshishige Suzuki, Yoshinobu Nakatani, Terunobu Miyazaki, Koji Ando

Curr. Appl. Phys.　10　(1)　e87-89　2010/04

DOI： 10.1016/j.cap.2009.12.021 　

ISSN： 1567-1739

eISSN： 1878-1675
Gilbert damping in perpendicularly magnetized Pt/Co/Pt films investigated by all-optical pump-probe technique Peer-reviewed

S. Mizukami, E. P. Sajitha, D. Watanabe, F. Wu, T. Miyazaki, H. Naganuma, M. Oogane, Y. Ando

APPLIED PHYSICS LETTERS　96　(15)　2010/04

DOI： 10.1063/1.3396983 　

ISSN： 0003-6951
Reproducible trajectory on subnanosecond spin-torque magnetization switching under a zero-bias field for MgO-based ferromagnetic tunnel junctions Peer-reviewed

Tatsuya Aoki, Yasuo Ando, Mikihiko Oogane, Hiroshi Naganuma

APPLIED PHYSICS LETTERS　96　(14)　2010/04

DOI： 10.1063/1.3380595 　

ISSN： 0003-6951
Epitaxial growth of Co2MnSi thin films at the vicinal surface of n-Ge(111) substrate Peer-reviewed

M. A. I. Nahid, M. Oogane, H. Naganuma, Y. Ando

APPLIED PHYSICS LETTERS　96　(14)　2010/04

DOI： 10.1063/1.3378986 　

ISSN： 0003-6951
Evidence of Fermi level control in a half-metallic Heusler compound Co2MnSi by Al-doping: Comparison of measurements with first-principles calculations Peer-reviewed

Y. Sakuraba, K. Takanashi, Y. Kota, T. Kubota, M. Oogane, A. Sakuma, Y. Ando

PHYSICAL REVIEW B　81　(14)　2010/04

DOI： 10.1103/PhysRevB.81.144422 　

ISSN： 2469-9950

eISSN： 2469-9969
Element-Specific Evaluation of Magnetic Moments in Ferrimagnetic Mn2Val Heusler Epitaxial Thin Films Peer-reviewed

T.Kubota, K. Kodama, T. Nakamura, Y. Sakuraba, M. Oogane, H. Naganuma, K. Takanashi, Y. Ando

J. Magn. Soc. Jpn.　34　(2)　100-106　2010/03
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.1002R0004 　

ISSN： 1882-2924

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We successfully fabricated L2₁-ordered Mn₂VAl Heusler thin films and evaluated their ferrimagnetic properties by soft x-ray magnetic circular dichroism (XMCD). The buffer layers and annealing temperatures were varied to prepare the Mn₂VAl films. We discovered that Mn₂VAl could be ordered in an L2₁ phase well when it was deposited directly onto an MgO (001) single crystalline substrate. The maximum values of L2₁ and B2 long-range order parameters we obtained were about 0.5 for both phases for samples without a buffer layer, when substrates were heated at 500°C or 600°C. The saturation magnetization (M_s) for these samples was roughly 150 emu/cc. This is rather small compared to that expected from the ideal Slater-Pauling behavior, which might be due to the suppressed degree of L2₁ or B2 ordering. Ferrimagnetism in the Mn₂VAl, ferrimagnetic coupling between Mn and V moments was clearly observed by using the XMCD technique in well-ordered L2₁-Mn₂VAl film as has been predicted in theoretical investigations.
Co-concentration dependence of half-metallic properties in Co-Mn-Si epitaxial films Peer-reviewed

Y. Sakuraba, N. Hirose, M. Oogane, T. Nakamura, Y. Ando, K. Takanashi

APPLIED PHYSICS LETTERS　96　(9)　2010/03

DOI： 10.1063/1.3330942 　

ISSN： 0003-6951

eISSN： 1077-3118
Optically induced magnetization dynamics and variation of damping parameter in epitaxial Co2MnSi Heusler alloy films Peer-reviewed

Y. Liu, L. R. Shelford, V. V. Kruglyak, R. J. Hicken, Y. Sakuraba, M. Oogane, Y. Ando

PHYSICAL REVIEW B　81　(9)　2010/03

DOI： 10.1103/PhysRevB.81.094402 　

ISSN： 2469-9950

eISSN： 2469-9969
Structural and magnetic properties of Mn(2.5)Ga films Peer-reviewed

F. Wu, S. Mizukami, D. Watanabe, H. Naganuma, M. Oogane, Y. Ando, T. Miyazaki

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　062037-1-062037-5　2010

DOI： 10.1088/1742-6596/200/6/062037 　

ISSN： 1742-6588
Structural characterization of epitaxial multiferroic BiFeO₃ films grown on SrTiO₃ (100) substrates by crystallizing amorphous Bi-Fe-O_x Peer-reviewed

H. Naganuma, T. Miyazaki, A. Ukachi, M. Oogane, S. Miukami, Y. Ando

J. Ceramic Soc. Jpn.　118　(1380)　648-651　2010
Publisher: The Ceramic Society of Japan
DOI： 10.2109/jcersj2.118.648 　

ISSN： 1882-0743

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Amorphous Bi–Fe–O_x films prepared on SrTiO₃ (100) substrates using a conventional r.f. magnetron sputtering system were crystallized by post-annealing at 873 K in an atmosphere. Microstructural observations by X-ray diffraction and cross-sectional transmission electron microscopy revealed that the crystallized Bi–Fe–O_x films were well-epitaxially BiFeO₃ fabricated without interfacial layer although as-prepared film was amorphous structure with excess Bi. The crystallized BiFeO₃ films have fairly epitaxial compatibly ([001](001)BiFeO₃ // [001](001)SrTiO₃). These results indicate that (1) BiFeO₃ has good epitaxial compatibility with SrTiO₃ and (2) crystallizing amorphous Bi–Fe–O_x is one possible method that can be used to fabricate high-quality multiferroic barriers for tunnel junctions.
Electrical transport properties of perpendicular magnetized Mn-Ga epitaxial films Peer-reviewed

Feng Wu, E. P. Sajitha, Shigemi Mizukami, Daisuke Watanabe, Terunobu Miyazaki, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

APPLIED PHYSICS LETTERS　96　(4)　2010/01

DOI： 10.1063/1.3298363 　

ISSN： 0003-6951

eISSN： 1077-3118
Magnetoresistance of Perpendicularly Magnetized Tunnel Junction Using L1(0)-CoNiPt with Low Saturation Magnetization Peer-reviewed

G. Kim, T. Hiratsuka, H. Naganuma, M. Oogane, Y. Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/5/052011 　

ISSN： 1742-6588
Structural, Magnetic, and Magnetotransport Properties of FePt/MgO/CoPt Perpendicularly Magnetized Tunnel Junctions Peer-reviewed

N. Inami, G. Kim, T. Hiratsuka, H. Naganuma, M. Oogane, Y. Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/5/052008 　

ISSN： 1742-6588
Magnetotransport properties of CoFeB/MgO/CoFe/MgO/CoFeB double barrier magnetic tunnel junctions with large negative magnetoresistance at room temperature Peer-reviewed

L. X. Jiang, H. Naganuma, M. Oogane, K. Fujiwara, T. Miyazaki, K. Sato, T. J. Konno, S. Mizukami, Y. Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/5/052009 　

ISSN： 1742-6588
Ultrafast Demagnetization for Ni80Fe20 and Half-metallic Co2MnSi Heusler Alloy Films Peer-reviewed

S. Mizukami, S. Tunegi, T. Kubota, M. Oogane, D. Watanabe, H. Naganuma, Y. Ando, T. Miyazaki

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/4/042017 　

ISSN： 1742-6588
Interlayer exchange coupling in perpendicularly magnetized synthetic ferrimagnet structure using CoCrPt and CoFeB Peer-reviewed

D. Watanabe, S. Mizukami, F. Wu, M. Oogane, H. Naganuma, Y. Ando, T. Miyazaki

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/7/072104 　

ISSN： 1742-6588
Spin-transfer Switching in Magnetic Tunnel Junctions with Synthetic Ferri-magnetic Free Layer Peer-reviewed

M. Nishimura, M. Oogane, H. Naganuma, N. Inami, S. Ikeda, H. Ohno, Y. Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/5/052018 　

ISSN： 1742-6588
Synthetic CoFeB/Ru/NiFe Free Layer on MgO Barrier Layer for Spin Transfer Switching Peer-reviewed

Takuya Ono, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/6/062019 　

ISSN： 1742-6588
Spin transistor based on double tunnel junctions using half-metallic Co2MnSi electrodes Peer-reviewed

Yusuke Ohdaira, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010

DOI： 10.1088/1742-6596/200/5/052019 　

ISSN： 1742-6588
Dynamic Magnetic Intermediate State during Nanosecond Spin Transfer Switching for MgO-Based Magnetic Tunnel Junctions Peer-reviewed

Tatsuya Aoki, Yasuo Ando, Mikihiko Oogane, Hiroshi Naganuma

APPLIED PHYSICS EXPRESS　3　(5)　2010

DOI： 10.1143/APEX.3.053002 　

ISSN： 1882-0778
Structure, exchange stiffness, and magnetic anisotropy of Co2MnAlxSi1-x Heusler compounds Peer-reviewed

Takahide Kubota, Jaroslav Hamrle, Yuya Sakuraba, Oksana Gaier, Mikihiko Oogane, Akimasa Sakuma, Burkard Hillebrands, Koki Takanashi, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　106　(11)　2009/12

DOI： 10.1063/1.3265428 　

ISSN： 0021-8979

eISSN： 1089-7550
Ferrimagnetism in epitaxially grown Mn2VAl Heusler alloy investigated by means of soft x-ray magnetic circular dichroism Peer-reviewed

Takahide Kubota, Kenji Kodama, Tetsuya Nakamura, Yuya Sakuraba, Mikihiko Oogane, Koki Takanashi, Yasuo Ando

APPLIED PHYSICS LETTERS　95　(22)　2009/11

DOI： 10.1063/1.3269609 　

ISSN： 0003-6951

eISSN： 1077-3118
The effect of MgO barrier on the structure and magnetic properties of Co2MnSi films on n-Si(100) substrates Peer-reviewed

M. A. I. Nahid, M. Oogane, H. Naganuma, Y. Ando

JOURNAL OF APPLIED PHYSICS　106　(10)　2009/11

DOI： 10.1063/1.3260253 　

ISSN： 0021-8979

eISSN： 1089-7550
Tunnel magnetoresistance in epitaxially grown magnetic tunnel junctions using Heusler alloy electrode and MgO barrier Peer-reviewed

S. Tsunegi, Y. Sakuraba, M. Oogane, N. D. Telling, L. R. Shelford, E. Arenholz, G. van der Laan, R. J. Hicken, K. Takanashi, Y. Ando

JOURNAL OF PHYSICS D-APPLIED PHYSICS　42　(19)　2009/10

DOI： 10.1088/0022-3727/42/19/195004 　

ISSN： 0022-3727

eISSN： 1361-6463
Study of Structure, Magnetic and Electrical Properties of Co2MnSi Heusler Alloy Thin Films Onto n-Si Substrates Peer-reviewed

M. A. I. Nahid, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

IEEE TRANSACTIONS ON MAGNETICS　45　(10)　4030-4032　2009/10

DOI： 10.1109/TMAG.2009.2024320 　

ISSN： 0018-9464

eISSN： 1941-0069
Direct Observation of Atomic Ordering and Interface Structure in Co2MnSi/MgO/Co2MnSi Magnetic Tunnel Junctions by High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy Peer-reviewed

Toyoo Miyajima, Mikihiko Oogane, Yasutoshi Kotaka, Takashi Yamazaki, Mineharu Tsukada, Yuji Kataoka, Hiroshi Naganuma, Yasuo Ando

APPLIED PHYSICS EXPRESS　2　(9)　2009/09

DOI： 10.1143/APEX.2.093001 　

ISSN： 1882-0778

eISSN： 1882-0786
Structural and Magnetic Properties of CO2MnSi Heusler Alloy Thin Films on Si Peer-reviewed

Muhammad Ariful Islam Nahid, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando

JAPANESE JOURNAL OF APPLIED PHYSICS　48　(8)　2009/08

DOI： 10.1143/JJAP.48.083002 　

ISSN： 0021-4922
Large Tunnel Magnetoresistance of 1056% at Room Temperature in MgO Based Double Barrier Magnetic Tunnel Junction (Retracted article. See vol. 4, artn no. 019201, 2011) Peer-reviewed

Lixian Jiang, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando

APPLIED PHYSICS EXPRESS　2　(8)　2009/08

DOI： 10.1143/APEX.2.083002 　

ISSN： 1882-0778

eISSN： 1882-0786
Enhancement in tunnel magnetoresistance effect by inserting CoFeB to the tunneling barrier interface in Co2MnSi/MgO/CoFe magnetic tunnel junctions Peer-reviewed

S. Tsunegi, Y. Sakuraba, M. Oogane, Hiroshi Naganuma, K. Takanashi, Y. Ando

APPLIED PHYSICS LETTERS　94　(25)　2009/06

DOI： 10.1063/1.3156858 　

ISSN： 0003-6951

eISSN： 1077-3118
Fabrication of MgO-based magnetic tunnel junctions with CoCrPt perpendicularly magnetized electrodes Invited Peer-reviewed

Daisuke Watanabe, Shigemi Mizukami, Mikihiko Oogane, Hiroshi Naganuma, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　105　(7)　2009/04

DOI： 10.1063/1.3062816 　

ISSN： 0021-8979
Low damping constant for Co2FeAl Heusler alloy films and its correlation with density of states Peer-reviewed

S. Mizukami, D. Watanabe, M. Oogane, Y. Ando, Y. Miura, M. Shirai, T. Miyazaki

JOURNAL OF APPLIED PHYSICS　105　(7)　2009/04

DOI： 10.1063/1.3067607 　

ISSN： 0021-8979
Tunnel magnetoresistance effect in double magnetic tunnel junctions using half-metallic Heusler alloy electrodes Invited Peer-reviewed

Yusuke Ohdaira, Mikihiko Oogane, Yasuo Ando

JOURNAL OF APPLIED PHYSICS　105　(7)　2009/04

DOI： 10.1063/1.3072023 　

ISSN： 0021-8979

eISSN： 1089-7550
Reduction in switching current using a low-saturation magnetization Co-Fe-(Cr, V)-B free layer in MgO-based magnetic tunnel junctions Peer-reviewed

Hitoshi Kubota, Akio Fukushima, Kay Yakushiji, Satoshi Yakata, Shinji Yuasa, Koji Ando, Mikihiko Ogane, Yasuo Ando, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　105　(7)　2009/04

DOI： 10.1063/1.3068484 　

ISSN： 0021-8979

eISSN： 1089-7550
Improvement of structural, electronic, and magnetic properties of Co2MnSi thin films by He+ irradiation Peer-reviewed

O. Gaier, J. Hamrle, B. Hillebrands, M. Kallmayer, P. Poersch, G. Schoenhense, H. J. Elmers, J. Fassbender, A. Gloskovskii, C. A. Jenkins, C. Felser, E. Ikenaga, Y. Sakuraba, S. Tsunegi, M. Oogane, Y. Ando

APPLIED PHYSICS LETTERS　94　(15)　2009/04

DOI： 10.1063/1.3119188 　

ISSN： 0003-6951

eISSN： 1077-3118
Electronic properties of Co2MnSi thin films studied by hard x-ray photoelectron spectroscopy Peer-reviewed

Siham Ouardi, Andrei Gloskovskii, Benjamin Balke, Catherine A. Jenkins, Joachim Barth, Gerhard H. Fecher, Claudia Felser, Mihaela Gorgoi, Marcel Mertin, Franz Schaefers, Eiji Ikenaga, Ke Yang, Keisuke Kobayashi, Takahide Kubota, Mikihiko Oogane, Yasuo Ando

JOURNAL OF PHYSICS D-APPLIED PHYSICS　42　(8)　2009/04

DOI： 10.1088/0022-3727/42/8/084011 　

ISSN： 0022-3727
Epitaxial Mn2.5Ga thin films with giant perpendicular magnetic anisotropy for spintronic devices Peer-reviewed

Feng Wu, Shigemi Mizukami, Daisuke Watanabe, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS LETTERS　94　(12)　2009/03

DOI： 10.1063/1.3108085 　

ISSN： 0003-6951
Half-metallicity and Gilbert damping constant in Co2FexMn1-xSi Heusler alloys depending on the film composition Peer-reviewed

Takahide Kubota, Sumito Tsunegi, Mikihiko Oogane, Shigemi Mizukami, Terunobu Miyazaki, Hiroshi Naganuma, Yasuo Ando

APPLIED PHYSICS LETTERS　94　(12)　2009/03

DOI： 10.1063/1.3105982 　

ISSN： 0003-6951

eISSN： 1077-3118
高反平行結合強度を有する積層フェリ構造の開発 Peer-reviewed

西村真之, 渡邉大輔, 大兼幹彦, 安藤康夫

Journal of the Magnetics Society of Japan　33　(3)　266-269　2009
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.0903RE8054 　

ISSN： 1882-2924

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We investigated the dependencies of the saturation field, H_s, for synthetic ferrimagnetic (SyF) structures with various stacking structures on annealing temperature and Ru middle layer thickness. The buffer layer was optimized using Co₇₅Fe₂₅/Ru/Co₇₅Fe₂₅-SyF. The SyF on the Ta/Ru buffer layer demonstrated high annealing stability and large H_s. Moreover, we investigated the dependence on annealing temperature of H_s for Ta(5 nm)/Ru(5 nm)/ ferromagnetic-layer/Ru(0.8 nm)/Co₄₀Fe₄₀B₂₀(2 nm) SyFs with various ferromagnetic layers. The SyFs using Co₇₅ Fe₂₅ and Ni₈₀Fe₂₀ ferromagnetic layers exhibited high annealing stability and large H_s. The dependence on Ru middle layer thickness of H_s for the SyFs consisting of Ta(5 nm)/Ru(5 nm)/Co₇₅ Fe₂₅(2 nm)/Ru(0.2-1.2 nm)/Co₄₀Fe₄₀B₂₀(2 nm)/ MgO(2.5 nm)/Ta(10 nm) was investigated. As a result, we demonstrated the possibility of fabricating CoFeB/MgO/ CoFeB MTJs with SyF having both high annealing stability and strong interlayer exchange coupling.
Co2FeMnSiホイスラー合金の磁気緩和定数 Peer-reviewed

大兼幹彦, 窪田崇秀, 廣瀬直紀, 安藤康夫

Journal of the Magnetics Society of Japan　33　(3)　270-273　2009
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.0903RE8063 　

ISSN： 1882-2924

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Magnetic damping constants of Co₂Fe_xMn_1-xSi (x = 0.0 - 1.0) Heusler alloy thin films have been investigated. Co₂Fe_xMn_1-xSi thin films were epitaxitially grown on the single crystal MgO(100) substrate using magnetron sputtering technique. Damping constants were estimated by analyzing the line width of ferromagnetic resonance (FMR) spectra. Damping constant of Co₂Fe_xMn_1-xSi films showed a minimum value of 0.003 at x = 0.4. This damping constant is very small compared with other ferromagnetic metals. Additionally, damping constants significantly increased above x = 0.6. In this article, the relationship between the damping constant and the half-metallicity of Co₂Fe_xMn_1-xSi films is discussed.
Co2MnSiを電極とする微小二重トンネル接合の作製と評価 Peer-reviewed

大平祐介, 大兼幹彦, 安藤康夫

Journal of the Magnetics Society of Japan　33　(3)　262-265　2009
Publisher: The Magnetics Society of Japan
DOI： 10.3379/msjmag.0903RE8052 　

ISSN： 1882-2924

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Double magnetic tunnel junctions (DMTJs) using half-metallic Heusler alloy Co₂MnSi electrodes were fabricated. A tunnel magneto-resistance ratio as large as 25% (at RT) and 320% (at 6 K) was observed in the DMTJs with various junction areas. The dependence of the tunnel magneto-resistance on bias voltage was a typical characteristic of DMTJs. These results indicate that high-quality DMTJs were stably fabricated.
Boron Composition Dependence of Spin-Transfer Switching in Magnetic Tunnel Junctions with CoFeB Free Layers Peer-reviewed

Daisuke Watanabe, Mikihiko Oogane, Shigemi Mizukami, Yasuo Ando, Terunobu Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS　48　(1)　2009/01

DOI： 10.1143/JJAP.48.013001 　

ISSN： 0021-4922

eISSN： 1347-4065
Tunnel magnetoresistance effect in magnetic tunnel junctions using epitaxial Co2FeSi Heusler alloy electrode Peer-reviewed

M. Oogane, M. Shinano, Y. Sakuraba, Y. Ando

J. Appl. Phys.　105　(7)　07C903-1-07C903-3　2009
Publisher: American Institute of Physics
DOI： 10.1063/1.3062814 　

ISSN： 0021-8979
Direct Observation of Atomic Ordering and Interface Structure Peer-reviewed

T. Miyajima, M. Oogane, Y. Kotaka, T. Yamazaki, M. Tsukada, Y. Kataoka, H. Naganuma, Y. Ando

Appl. Phys. Express　2009
Evidence of local moment formation in Co-based Heusler alloys Peer-reviewed

Telling, ND, Keatley, PS, van der Laan, G, Hicken, RJ, Arenholz, E, Sakuraba, Y, Oogane, M, Ando, Y, Takanashi, K, Sakuma, A, Miyazaki, T

Phys. Rev. B　78　(18)　184438　2008/11

DOI： 10.1103/PhysRevB.78.184438 　
Electrical conductance properties for magnetic tunnel junctions with MgO barriers Invited Peer-reviewed

K. Tamanoi, M. Sato, M. Oogane, Y. Ando, T. Tanaka, Y. Uehara, T. Uzumaki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　320　(22)　2959-2962　2008/11

DOI： 10.1016/j.jmmm.2008.08.004 　

ISSN： 0304-8853
Large tunnel magnetoresistance in magnetic tunnel junctions using a Co2MnSi Heusler alloy electrode and a MgO barrier Peer-reviewed

Sumito Tsunegi, Yuya Sakuraba, Mikihiko Oogane, Koki Takanashi, Yasuo Ando

APPLIED PHYSICS LETTERS　93　(11)　2008/09

DOI： 10.1063/1.2987516 　

ISSN： 0003-6951
Temperature dependence of the interface moments in Co2MnSi thin films Peer-reviewed

N. D. Telling, P. S. Keatley, L. R. Shelford, E. Arenholz, G. van der Laan, R. J. Hicken, Y. Sakuraba, S. Tsunegi, M. Oogane, Y. Ando, K. Takanashi, T. Miyazaki

APPLIED PHYSICS LETTERS　92　(19)　2008/05

DOI： 10.1063/1.2927482 　

ISSN： 0003-6951

eISSN： 1077-3118
Spin transfer switching in the nanosecond regime for CoFeB/MgO/CoFeB ferromagnetic tunnel junctions Peer-reviewed

Tatsuya Aoki, Yasuo Ando, Daisuke Watanabe, Mikihiko Oogane, Terunobu Miyazaki

JOURNAL OF APPLIED PHYSICS　103　(10)　2008/05

DOI： 10.1063/1.2930873 　

ISSN： 0021-8979
Influence of the L2(1) ordering degree on the magnetic properties of Co2MnSi Heusler films Peer-reviewed

O. Gaier, J. Hamrle, S. J. Hermsdoerfer, H. Schultheiss, B. Hillebrands, Y. Sakuraba, M. Oogane, Y. Ando

JOURNAL OF APPLIED PHYSICS　103　(10)　2008/05

DOI： 10.1063/1.2931023 　

ISSN： 0021-8979

eISSN： 1089-7550
Tunneling magnetoresistance of magnetic tunnel junctions using perpendicular magnetization L1(0)-CoPt electrodes Peer-reviewed

Gukcheon Kim, Yuya Sakuraba, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS LETTERS　92　(17)　2008/04

DOI： 10.1063/1.2913163 　

ISSN： 0003-6951
Magnetic second harmonic generation at the Co2MnSi/AlOx interface Peer-reviewed

L. R. Shelford, Y. Liu, R. J. Hicken, Y. Sakuraba, M. Oogane, Y. Ando

JOURNAL OF APPLIED PHYSICS　103　(7)　2008/04

DOI： 10.1063/1.2841174 　

ISSN： 0021-8979

eISSN： 1089-7550
Tunnel magnetoresistance effect in magnetic tunnel junctions using a Co2MnSi(110) electrode Peer-reviewed

Masashi Hattori, Yuya Sakuraba, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

APPLIED PHYSICS EXPRESS　1　(2)　2008/02

DOI： 10.1143/APEX.1.021301 　

ISSN： 1882-0778

eISSN： 1882-0786
Formation and developments of spintronics research field Invited Peer-reviewed

Terunobu Miyazaki, Mikihiko Oogane, Yuuya Sakuraba, Daisuke Watanabe, Resul Yilgin, Akimasa Sakuma, Yasuo Ando, Hitoshi Kubota

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy　55　(2)　109-115　2008/02

DOI： 10.2497/jjspm.55.109 　

ISSN： 0532-8799
Nonquasiparticle states in Co2MnSi evidenced through magnetic tunnel junction spectroscopy measurements Peer-reviewed

L. Chioncel, Y. Sakuraba, E. Arrigoni, M. I. Katsnelson, M. Oogane, Y. Ando, T. Miyazaki, E. Burzo, A. I. Lichtenstein

PHYSICAL REVIEW LETTERS　100　(8)　2008/02

DOI： 10.1103/PhysRevLett.100.086402 　

ISSN： 0031-9007

eISSN： 1079-7114
Lower-current and Fast switching of A Perpendicular TMR for High Speed and High density Spin-Transfer-Torque MRAM Peer-reviewed

Kishi T, Yoda H, Kai T, Nagase T, Kitagawa E, Yoshikawa M, Nishiyama K, Daibou T, Nagamine M, Amano M, Takahashi S, Nakayama M, Shimomura N, Aikawa H, Ikegawa S, Yuasa S, Yakushiji K, Kubota H, Fukushima A, Oogane M, Miyazaki T, Ando K, IEEE

Ieee International Electron Devices Meeting 2008, Technical Digest　309-+　2008
Gilbert Damping for Various Ni₈₀Fe₂₀ Thin Films Investigated Using All-Optical Pump-Probe Detection and Ferromagnetic Resonance, Peer-reviewed

S. Mizukami, H. Abe, D. Watanabe, M. Oogane, Y. Ando, T. Miyazaki

Appl. Phys. Exp　1　(12)　121301-1-121301-3　2008
Publisher: The Japan Society of Applied Physics
DOI： 10.1143/APEX.1.121301 　

ISSN： 1882-0778

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All-optical pump--probe detection of magnetization precession has been performed to investigate Gilbert damping in several types of Ni80Fe20 films. The frequency and decay time of magnetization precession depended on pump fluence. At low pump fluence, Gilbert damping constants, derived from the magnetic field dependence on frequency and decay time of magnetization precession, were identical to values obtained from X-band ferromagnetic resonance within the experimental errors.
TMR素子を用いた高感度地磁気センサーの開発 Peer-reviewed

高太好, 大兼幹彦, 安藤康夫

日本磁気学会誌　32　(3)　361-365　2008
Publisher: The Magnetics Society of Japan (MSJ)
DOI： 10.3379/msjmag.32.361 　

ISSN： 1882-2924

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The TMR (Tunneling Magneto-resistive) junctions of SiO₂-sub./bottom-electrode/IrMn/CoFe/Al-oxide/NiFe/ top-electrode were fabricated. We have succeeded to observe both high sensitivity and linearity in a low magnetic field for the optimized TMR junctions. The circuit of magnetic sensor using developed TMR junctions exhibited high output signal enough to resolve over 36 directions at terrestrial magnetism. The terrestrial sensor using TMR junctions is very small size and low energy consumption, so will be key "tools" for some solutions, for example, a navigation sensor with Global Positioning System(GPS) in cell phones.
Study of a Spin Torque Transfer MRAM with Perpendicular Magnetization TMR Elements as a High Density Non-volatile Memory Peer-reviewed

H. Yoda, M. Oogane

Electrochem. Soc　2008
CoFeB/MgO/CoFeBトンネル接合のナノ秒領域におけるスピン注入磁化反転と実時間測定 Peer-reviewed

青木達也, 大兼幹彦, 宮崎照宣, 安藤康夫

Journal of the Magnetics Society of Japan　32　(3)　355-360　2008
Publisher: The Magnetics Society of Japan (MSJ)
DOI： 10.3379/msjmag.32.355 　

ISSN： 1882-2924

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Detailed spin-transfer switching (STS) properties in the nanosecond regime were investigated. We prepared a CoFeB/MgO/CoFeB magnetic tunnel junction that exhibits a 115 % magnetoresistance ratio. The STS property in the ≥ 2 ns region was obtained by static measurement. We then examined this property from several points of view. In addition, we outlined a new method of real-time switching observation. That is expected to clarify the STS mechanism directly. Using this method, the contribution of the thermal activation effect in a switching current below I_C0 was successfully detected. This indicates that the real-time method has the advantage that it clarifies the STS mechanism.
高配向Nd2Fe14B薄膜のX線回折と磁気特性 Peer-reviewed

小川大介, 秋屋貴博, 大兼幹彦, 安藤康夫, 加藤宏朗

Journal of the Magnetics Society of Japan　32　(6)　548-553　2008
Publisher: The Magnetics Society of Japan (MSJ)
DOI： 10.3379/msjmag.32.548 　

ISSN： 1882-2924

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Nd₂Fe₁₄B thin films were fabricated with a DC magnetron sputtering system. X-ray diffraction experiments and the Rietveld analysis showd that the crystallites of the Nd₂Fe₁₄B phase were highly oriented perpendicular to the film plane. In addition to the diffraction peaks originated from the Nd₂Fe₁₄B phase, we observed extra reflections that can be assigned as a NdO phase. The relative intensity, hence the volume fraction of the NdO phase varied depending on the sputtering conditions such as the substrate temperature, Ar gas pressure, and Ta buffer layer thickness. It was found that the magnetization value depends strongly on the Ar gas pressure and reaches a maximum at 0.7 Pa of Ar gas pressure. The maximum magnetization value is 15 kG, which is comparable with the bulk value. The optimized values of the maximum energy product, saturation magnetization, and coercivity are (BH)_max = 36 MGOe, 4πM_s = 14.7 kG, and H_c = 6.7 kOe, respectively.
Ultrafast optical modification of magnetic anisotropy and stimulated precession in an epitaxial Co2MnAl thin film Peer-reviewed

Y. Liu, L. R. Shelford, V. V. Kruglyak, R. J. Hicken, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF APPLIED PHYSICS　101　(9)　2007/05

DOI： 10.1063/1.2711702 　

ISSN： 0021-8979

eISSN： 1089-7550
New magnetic nanodot memory with FePt nanodots Peer-reviewed

Cheng-Kuan Yin, Mariappan Murugesan, Ji-Chel Bea, Mikihiko Oogane, Takafumi Fukushima, Tetsu Tanaka, Shozo Kono, Seiji Samukawa, Mitsumasa Koyanagi

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　46　(4B)　2167-2171　2007/04

DOI： 10.1143/JJAP.46.2167 　

ISSN： 0021-4922
Half-metallic band structure observed in Co2MnSi-based magnetic tunnel junctions Peer-reviewed

Y. Sakuraba, M. Hattori, M. Oogane, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki

Journal of Physics D: Applied Physics　40　(5)　1221-1227　2007/03/07

DOI： 10.1088/0022-3727/40/5/S02 　

ISSN： 0022-3727 1361-6463
Gilbert damping constant in polycrystalline CO2MnSi Heusler alloy films Peer-reviewed

R. Yilgin, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　310　(2)　2322-2323　2007/03

DOI： 10.1016/j.jmmm.2006.11.032 　

ISSN： 0304-8853
Boron effects on noise in magnetic tunnel junctions Peer-reviewed

A. F. Md Nor, T. Daibou, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　310　(2)　1917-1919　2007/03

DOI： 10.1016/j.jmmm.2006.10.1126 　

ISSN： 0304-8853
Bias voltage dependence of tunnel magnetoresistance effect in CoFeB/MgO/Co2X(X = Fe, Mn)Si magnetic tunnel junctions Peer-reviewed

T. Daibou, M. Shinano, M. Hattori, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　310　(2)　1926-1928　2007/03

DOI： 10.1016/j.jmmm.2006.10.761 　

ISSN： 0304-8853
Tunneling spin polarization and magnetic properties of Co-Fe-B alloys and their dependence on boron content Peer-reviewed

Takahide Kubota, Tadaomi Daibou, Mikihiko Oogane, Yasuo Ando, Terunobu Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS　46　(8-11)　L250-L252　2007/03

DOI： 10.1143/JJAP.46.L250 　

ISSN： 0021-4922
Co2MnSiを用いた強磁性トンネル接合における極高スピン分極率の実現 Peer-reviewed

桜庭裕弥, 服部正志, 大兼幹彦, 久保田均, 安藤康夫, 宮﨑照宣

日本応用磁気学会誌　31　(4)　338-343　2007
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.31.338 　

ISSN： 0285-0192

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We fabricated Co₂MnSi/(Mg)/Al-O/CoFe MTJs using UHV magnetron sputtering. The interfacial chemical bond between Co₂MnSi and Al-O was intensively optimized by changing plasma oxidation time for Al-O and by inserting a Mg layer. The Mg inserted layer between Co₂MnSi and Al-O effectively suppressed the generation of interfacial magnetic impurities. Finally, we successfully observed a giant TMR ratio of 203% at 2 K in the MTJ with a 1.0 nm-Mg layer inserted. The spin-polarization for Co₂MnSi estimated from this TMR ratio was 0.97-1.00, which indicated that an almost perfect spin-polarized state was achieved. We also investigated the relationship between the TMR ratio and the site-ordering level of Co₂MnSi. As a result, we found that an L2₁-ordering state is not necessary to achieve high spin-polarization for Co₂MnSi in MTJs.
Interfacial structure and half-metallic ferromagnetism in Co2MnSi-based magnetic tunnel junctions Peer-reviewed

N. D. Telling, P. S. Keatley, G. van der Laan, R. J. Hicken, E. Arenholz, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

PHYSICAL REVIEW B　74　(22)　2006/12

DOI： 10.1103/PhysRevB.74.224439 　

ISSN： 2469-9950

eISSN： 2469-9969
Tunnel magnetoresistance effect in CoFeB/MgO/Co2FeSi and Co2MnSi tunnel junctions Peer-reviewed

T. Daibou, M. Shinano, M. Hattori, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

IEEE TRANSACTIONS ON MAGNETICS　42　(10)　2655-2657　2006/10

DOI： 10.1109/TMAG.2006.879733 　

ISSN： 0018-9464

eISSN： 1941-0069
Direct observation of half-metallic energy gap in Co2MnSi by tunneling conductance spectroscopy Peer-reviewed

Y. Sakuraba, T. Miyakoshi, M. Oogane, Y. Ando, A. Sakuma, T. Miyazaki, H. Kubota

APPLIED PHYSICS LETTERS　89　(5)　052508　2006/07

DOI： 10.1063/1.2335583 　

ISSN： 0003-6951

eISSN： 1077-3118
Magnetic damping in ferromagnetic thin films Peer-reviewed

Mikihiko Oogane, Takeshi Wakitani, Satoshi Yakata, Resul Yilgin, Yasuo Ando, Akimasa Sakuma, Terunobu Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　45　(5A)　3889-3891　2006/05

DOI： 10.1143/JJAP.45.3889 　

ISSN： 0021-4922
Giant tunneling magnetoresistance in Co2MnSi/Al-O/Co2MnSi magnetic tunnel junctions Peer-reviewed

Y. Sakuraba, M. Hattori, M. Oogane, Y. Ando, H. Kato, A. Sakuma, T. Miyazaki, H. Kubota

APPLIED PHYSICS LETTERS　88　(19)　192508　2006/05

DOI： 10.1063/1.2202724 　

ISSN： 0003-6951

eISSN： 1077-3118
Fabrication and evaluation of magnetic tunnel junction with MgO tunneling barrier Peer-reviewed

Takeshi Sakaguchi Hoon Choi, Ahn Sung-Jin, Takeaki Sugimura, Mungi Park, Milcihiko Oogane, Hyuckjae Oh, Jun Hayakawa, Shoji Ikeda, Young Min Lee, Takafumi Fukushima, Terunobu Miyazaki, Hideo Ohno, Mitsumasa Koyanagi

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS　45　(4B)　3228-3232　2006/04

DOI： 10.1143/JJAP.45.3228 　

ISSN： 0021-4922
Tunneling spectroscopy in CoFeB/MgO/CoFeB magnetic tunnel junctions Peer-reviewed

K Ono, T Daibou, SJ Ahn, Y Sakuraba, T Miyakoshi, T Morita, Y Kikuchi, M Oogane, Y Ando, T Miyazaki

JOURNAL OF APPLIED PHYSICS　99　(8)　2006/04

DOI： 10.1063/1.2173628 　

ISSN： 0021-8979
Large tunnel magnetoresistance in magnetic tunnel junctions using Co 2MnX (X ≤ Al, Si) Heusler alloys Invited Peer-reviewed

M. Oogane, Y. Sakuraba, J. Nakata, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki

Journal of Physics D: Applied Physics　39　(5)　834-841　2006/03/07

DOI： 10.1088/0022-3727/39/5/S09 　

ISSN： 0022-3727
Low-frequency noise in MgO magnetic tunnel junctions Peer-reviewed

A. F. M. Nor, T. Kato, S. J. Ahn, T. Daibou, K. Ono, M. Oogane, Y. Ando, T. Miyazaki

J. Appl. Phys.　99　08T306-1-08T306-3　2006

DOI： 10.1063/1.2165142 　
FMRを用いた強磁性金属中におけるスピン拡散長の測定 Peer-reviewed

家形諭, 安藤康夫, 大兼幹彦, 宮崎照宣

日本応用磁気学会誌　31　2006
Fabrication of Co2MnAl Heusler Alloy Epitaxial Film Using Cr Buffer Layer Peer-reviewed

Y. Sakuraba, J. Nakata, M. Oogane, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki

Jpn. J. Appl. Phys.　44　2006

DOI： 10.1143/JJAP.44.6535 　
Magnetic tunnel junctions using B2-ordered Co2MnAl Heusler alloy epitaxial electrode Peer-reviewed

Y Sakuraba, J Nakata, M Oogane, Y Ando, H Kato, A Sakuma, T Miyazaki, H Kubota

APPLIED PHYSICS LETTERS　88　(2)　022503　2006/01

DOI： 10.1063/1.2162867 　

ISSN： 0003-6951
Low frequency noise in CoFeB/MgO(100)/CoFeB magnetic tunnel junctions Peer-reviewed

A. F. Md Nor, T. Daibou, M. Oogane, Y. Ando, T. Miyazaki

INTERMAG 2006 - IEEE International Magnetics Conference　858　2006

DOI： 10.1109/INTMAG.2006.374889 　
Anisotropic Intrinsic Damping Constant in Epitaxial Co2MnSi Heusler Alloy Films Peer-reviewed

R. Yilgin, Y. Sakuraba, M. Oogane, S. Mizukami, Y. Ando, T. Miyazaki

Jpn. J. Appl. Phys.　46　(9)　L205-L208　2006
Publisher: INSTITUTE OF PURE AND APPLIED PHYSICS
DOI： 10.1143/JJAP.46.L205 　

ISSN： 0021-4922

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We investigated the Gilbert damping constant of the Heusler Co2MnSi(001) films epitaxially grown on a MgO(100) substrate by a ferromagnetic resonance technique. The angular variation in resonance field in the in-plane geometry exhibited a maximum when the field was applied parallel to the [110] direction (easy axis), and its relative minimum corresponded to the $\mathrm{H}\parallel[100]$ hard axis. Experimental results were fitted with theoretical results; the $g$-value, effective magnetization and anisotropy constants were determined. The magneto-crystalline anisotropy of the films decreased after the films were post-annealed at 400 °C. The Gilbert damping parameter was anisotropic and had a minimum value at 300 °C.
Gilbert Damping Constants of Co2FeSi Heusler Alloy Film Peer-reviewed

M. Oogane, R. Yilgin, S. Shinano, S. Yakata, H. Kubota, Y. Ando, T. Miyazaki

J. Appl. Phys.　2006
コプレーナ伝送路を有する微小強磁性トンネル接合の作製 Peer-reviewed

青木達也, 渡邉大輔, 大坊忠臣, 安藤康夫, 大兼幹彦, 宮﨑照宣

日本応用磁気学会誌　31　(2)　94-97　2006
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.31.94 　

ISSN： 0285-0192

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Investigation of current induced magnetization switching properties in nanosecond regime in ferromagnetic tunnel junctions is increasing its necessity for realization of fast operating magnetic random access memory (MRAM). In this work, appropriate electrode structures for such a measurement were investigated. The electrode structure was designed as a typical coplanar waveguide with 50Ω characteristic impedance (structure A). Although the buffer layer thickness and the distance between the signal line and the ground line were altered, the large frequency dependenceof the insertion loss was not improved. The revised structure (structure B) with small cross section area between the signal line and the ground line showed very flat transmission properties over 20 GHz. Consequently, submicron sized Ta/FeNi/IrMn/CoFe/Ru/CoFeB/MgO/CoFeB/Ta/Ru ferromagnetic tunnel junctions with the electrodes of structure Bwere fabricated. The tunnel magnetoresistance ratio was 108 % after annealing at 250 °C.
Co2MnSi (110)ホイスラー合金を用いたトンネル接合における磁気抵抗効果 Peer-reviewed

服部正志, 桜庭裕弥, 大兼幹彦, 安藤康夫, 宮﨑照宣

日本応用磁気学会誌　2006
CoFeB合金薄膜の磁気緩和定数測定 Peer-reviewed

大兼幹彦, 渡邉美穂, 家形諭, 安藤康夫, 宮﨑照宣

日本応用磁気学会誌　2006
Intrinsic Gilbert damping constant in CO2MnAl Heusler alloy films Peer-reviewed

R Yilgin, M Oogane, S Yakata, Y Ando, T Miyazaki

IEEE TRANSACTIONS ON MAGNETICS　41　(10)　2799-2801　2005/10

DOI： 10.1109/TMAG.2005.854832 　

ISSN： 0018-9464

eISSN： 1941-0069
Spin-dependent tunneling spectroscopy in single-crystal Fe/MgO/Fe tunnel junctions Peer-reviewed

Y Ando, T Miyakoshi, M Oogane, T Miyazaki, H Kubota, K Ando, S Yuasa

APPLIED PHYSICS LETTERS　87　(14)　2005/10

DOI： 10.1063/1.2077861 　

ISSN： 0003-6951
Fabrication and Evaluation of Magnetic Tunnel Junction with MgO Tunneling Barrier Peer-reviewed

Takeshi Sakaguchi, Hoon Choi, Takeaki Sugimura, Mikihiko Oogane, Hyuckjae Oh, Jun Hayakawa, Shoji Ikeda, Young Min Lee, Takafumi Fukushima, Terunobu Miyazaki, Hideo Ohno, Mitsumasa Koyanagi

International Conference on Solid State Device and Materials (SSDM)　2005　642-643　2005/09
Fabrication and characterization of Co-Mn-Al Heusler-type thin film Peer-reviewed

H Kubota, J Nakata, M Oogane, Y Ando, H Kato, A Sakuma, T Miyazaki

JOURNAL OF APPLIED PHYSICS　97　(10)　2005/05

DOI： 10.1063/1.1852329 　

ISSN： 0021-8979

eISSN： 1089-7550
Fabrication of heusler-type Co2MnAl epitaxial films by using sputtering method

Y. Sakuraba, J. Nakata, M. Oogane, H. Kubota, Y. Ando, H. Kato, A. Sakuma, T. Miyazaki

INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference　725　2005
Investigation of intrinsic gilbert damping constant in Co 2MnAl heusler alloy films

R. Yilgin, M. Oogane, S. Yakata, Y. Ando, T. Miyazaki

INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference　936　2005
Inelastic electron tunneling spectroscopy in magnetic tunnel junctions with MgO(001) tunnel barrier

T. Miyakoshi, Y. Ando, M. Oogane, T. Miyazaki, H. Kubota, A. Fukushima, T. Nagahama, S. Yuasa

INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference　237　2005
Publisher: IEEE Computer Society
DOI： 10.1109/intmag.2005.1463665 　
Huge spin-polarization of L2(1)-ordered Co2MnSi epitaxial Heusler alloy film Peer-reviewed

Y Sakuraba, J Nakata, M Oogane, H Kubota, Y Ando, A Sakuma, T Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS　44　(33-36)　L1100-L1102　2005

DOI： 10.1143/JJAP.44.L1100 　

ISSN： 0021-4922
Temperature dependence of tunnel magnetoresistance in Co-Mn-Al/Al-oxide/Co-Fe junctions Peer-reviewed

M Oogane, J Nakata, H Kubota, Y Ando, A Sakuma, T Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS　44　(24-27)　L760-L762　2005

DOI： 10.1143/JJAP.44.L760 　

ISSN： 0021-4922
Spin-dependent inelastic electron tunneling spectroscopy of magnetic tunnel junctions Peer-reviewed

M Hayashi, Y Ando, M Oogane, H Kubota, T Miyazaki

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　43　(11A)　7472-7476　2004/11

DOI： 10.1143/JJAP.43.7472 　

ISSN： 0021-4922
Tunnel Conductance in Ni80Fe20/Al-oxide/Al Junctions below the Superconducting Temperature of Al Films Peer-reviewed

M. Oogane, T. Daibou, H. Kubota, Y. Ando, T. Miyazaki

Transactions of Magnetic Research Society of Japan　2004/08
Large magnetoresistance in magnetic tunnel junctions using Co-Mn-Al full heusler alloy Peer-reviewed

Hitoshi Kubota, Jun Nakata, Mikihiko Oogane, Yasuo Ando, Akimasa Sakuma, Terunobu Miyazaki

Japanese Journal of Applied Physics, Part 2: Letters　43　(7 B)　L984-L986　2004/07/15

DOI： 10.1143/JJAP.43.L984 　

ISSN： 0021-4922
Tunnel spectra for Al/Al-oxide/Ni80Fe20 junctions under the superconducting transition temperature of Al films Peer-reviewed

M. Oogane, T. Daibou, H. Kubota, Y. Ando, T. Miyazaki

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　272　E1515-E1516　2004/05

DOI： 10.1016/j.jmmm.2003.12.318 　

ISSN： 0304-8853
Ferromagnetic Tunnel Junctions Using Co₂MnAl Heusler Alloy Peer-reviewed

J. Nakata, M. Oogane, H. Kubota, Y. Ando, H. Kato, T. Miyazaki

J. Magn. Soc. Jpn.　28　(4)　573-576　2004
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.28.573 　

ISSN： 0285-0192

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We investigated the structural and magnetic properties of Co₂MnAl thin films with Cr buffer layers, and the tunnel magnetoresistance (TMR) effect of junctions using Co₂MnAl Heusler alloy. The saturation magnetization of Co₂MnAl film deposited at 350°C was 711 emu/cm³ which was almost the same as that reported for bulk. The maximum TMR ratio of the junctions was 12% at room temperature and 26% at 25K. TMR ratio increased to 17% at room temperature after annealing at 200°C for one hour.
Magnetic tunnel junctions with high magnetoresistance and small bias voltage dependence using epitaxial NiFe(111) ferromagnetic bottom electrodes Peer-reviewed

JH Yu, HM Lee, M Hayashi, M Oogane, T Daibou, H Nakamura, H Kubota, Y Ando, T Miyazaki

JOURNAL OF APPLIED PHYSICS　93　(10)　8555-8557　2003/05

DOI： 10.1063/1.1544458 　

ISSN： 0021-8979
Interface characterization of magnetic tunnel junctions by using tunneling spectroscopy Peer-reviewed

Y Ando, M Hayashi, M Oogane, H Kubota, T Miyazaki

JOURNAL OF APPLIED PHYSICS　93　(10)　7023-7025　2003/05

DOI： 10.1063/1.1540172 　

ISSN： 0021-8979

eISSN： 1089-7550
Microfabrication and Magnetoelectric Properties of High-magnetoresistance Tunnel Junctions Peer-reviewed

X. F. Han, M. Oogane, T. Daibou, K. Yaoita, Y. Ando, H. Kubota, T. Miyazaki

J. Magn. Soc. Jpn.　25　(4)　707-710　2001
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.25.707 　

ISSN： 0285-0192

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Spin-valve-type tunnel junctions with structure of Ta(5nm)/Ni₇₉Fe₂₁(3 nm)/Cu(20 nm)/Ni₇₉Fe₂₁(3 nm)/Ir₂₂Mn₇₈ (10 nm)/Co₇₅Fe₂₅(4 nm)/Al(0.80 nm)-oxide /Co₇₅Fe₂₅(4 nm)/Ni₇₉Fe₂₁(20 nm)/Ta(5 nm) were fabricated using a microfabrication technique. The optical lithography combined with Ar ion-beam etching and CF₄ active etching was used to pattern the junction area with the size from 100x100 down to 3x3 μm². A thinner barrier layer and a short plasma-oxidation time for Al-oxide layer were used in order to reduce the junction resistance and increase the TMR ratio. High TMR ratio of 69.1% at 4.2 K and 49.7% at room temperature were achieved. A spin-electron polarization tunneling model, based on magnon emission or absorption by the tunneling electrons during the tunnel process, was extended by defining an anisotropic wavelength cutoff energy of spin-wave in this work. Intrinsic magnetoelectric properties, such as the temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias can be self-consistently evaluated using this extended model and a unique set of intrinsic parameters.
Tunnel Magnetoresistance Effect for Double Tunnel Junctions with Al Intermediate Layer Peer-reviewed

T. Daibou, M. Oogane, Y. Ando, C. K. Kim, O. Song, T. Miyazaki

J. Magn. Soc. Jpn.　25　(4)　767-770　2001
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.25.767 　

ISSN： 0285-0192

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Tunnel magnetoresistance for double barrier tunnel junctions with an intermediate layer of metallic Al was investigated. The junction with a 40-Å intermediate layer of Al showed a about 8.5%. TMR ratio. The TMR ratio decreased with increasing Al thickness and became zero at 100 Å. At a low temperature, Al thin film was expected to be in transition to superconductor. A superconducting gap was observed in the two junctions with 40-Å and 100-Å Al at about 0.4 K.
Spin Dependent Transport Properties in Ferromagnetic Double Barrier Junction Peer-reviewed

T. Siripongsakul, M. Oogane, Andrew C. C. Yu, H. Kubota, Y. Ando, T. Miyazaki, Changkyung Kim, Ohsung Song

J. Magn. Soc. Jpn.　25　(4)　763-766　2001
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.25.763 　

ISSN： 0285-0192

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Ferromagnetic double barrier junctions of Co₇₅Fe₂₅/ Al₂O₃/ Co₇₅Fe₂₅(X)/ Al₂O₃/ Co₇₅Fe₂₅ with discontinuous middle Co₇₅Fe₂₅ layers (X = 0, 0.7, 1.3, 2.0 nm) were fabricated, and magnetoresistance of these junctions was measured by a dc-4-probe method. At low temperature, the resistance and TMR ratio increased rapidly. This result implies the existence of a charging effect due to the Coulomb-blockade. At temperatures below 50 K, an ac-modulation method was used to measure bias-voltage dependence of the TMR ratio. We observed an increase in TMR ratio for the case of dc transport at low bias voltage. On the other hand, the TMR ratio decreased for the case of ac transport. At high bias voltage and at high temperature, however, we observed no difference between these methods. Such transport properties could be explained by a co-tunneling process.
Analyses of intrinsic magnetoelectric properties in spin-valve-type tunnel junctions with high magnetoresistance and low resistance Peer-reviewed

Xiu-Feng Han, Andrew C.C. Yu, Mikihiko Oogane, Junichirou Murai, Tadaomi Daibou, Terunobu Miyazaki

Physical Review B - Condensed Matter and Materials Physics　63　(22)　2001

DOI： 10.1103/PhysRevB.63.224404 　

ISSN： 1550-235X 1098-0121
Fabrication of high-magnetoresistance tunnel junctions using Co75Fe25 ferromagnetic electrodes Peer-reviewed

XF Han, M Oogane, H Kubota, Y Ando, T Miyazaki

APPLIED PHYSICS LETTERS　77　(2)　283-285　2000/07

ISSN： 0003-6951
Applied voltage and temperature dependence of tunneling magnetoresistance Peer-reviewed

N. Tezuka, M. Oogane, T. Miyazaki

Journal of Magnetism and Magnetic Materials　1999/03

DOI： 10.1016/S0304-8853(98)01056-7 　
強磁性体/Al－Oxide/Co接合のトンネル磁気抵抗効果の印加電圧及び温度依存性 Peer-reviewed

大兼幹彦, 手束展規, 宮崎照宣

日本応用磁気学会誌　23　(4)　1297-1300　1999
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.23.1297 　

ISSN： 0285-0192

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Ferromagnetic tunneling junctions with various thicknesses of the first ferromagnetic layer were fabricated. Co and Ni₈₀Fe₂₀ were used as the first ferromagnetic layer, and their thicknesses were varied between 10 and 200 Å. The voltage and temperature dependence of the tunneling magnetoresistance (TMR) ratio and conductance characteristic were investigated for these junctions. A drastic decrease in the conductance near the zero bias in the conductance-voltage characteristics (zero-bias anomaly) was observed in some junctions. A rapid decrease in the TMR ratio below 5 mV and 50 K was also observed in the same junctions. A slight decrease in the TMR ratio above 10 mV and 100 K was observed in all junctions. We investigated the origin of the voltage and temperature dependence of the TMR ratio by taking account of the magnetic impurity and magnon effect.
Ni80Fe20/Al－Oxide/Co接合におけるトンネル磁気抵抗比のNi80Fe20膜厚依存性 Peer-reviewed

大兼幹彦, 手束展規, 宮崎照宣

日本応用磁気学会誌　23　(4)　1309-1312　1999
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.23.1309 　

ISSN： 0285-0192

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Ferromagnetic tunneling junctions with various thicknesses of the first ferromagnetic layer were fabricated. Ni₈₀Fe₂₀ and Co were used as the first ferro-magnetic layer, and their thicknesses were varied between 10 and 200 Å. The tunneling magnetoresistance (TMR) ratio decreased and the shape of the TMR curve changed with decreasing Ni₈₀Fe₂₀ thickness, but changed only slightly with decreasing Co thickness. We calculated the TMR and magnetization curves by using a simple model that takes account of magnetic anisotropy to explain the change in the TMR ratio and the shape of the TMR curve with changing Ni₈₀Fe₂₀ thickness.

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Misc. 58

Progress on Development of Highly Sensitive Tunnel Magneto-resistive Sensor

Mikihiko Oogane, Takafumi Nakano, Kosuke Fujiwara

IEEJ Transactions on Fundamentals and Materials　144　(8)　306-311　2024

DOI： 10.1541/ieejfms.144.306 　

ISSN： 0385-4205

eISSN： 1347-5533
Recent progress of bio-magnetic field measurement by TMR sensors

大兼幹彦, 大兼幹彦, 藤原耕輔, 菅野彰剛, 中野貴文, 我妻宏, 有本直, 水上成美, 水上成美, 熊谷静似, 松崎斉, 松崎斉, 中里信和, 安藤康夫, 安藤康夫

応用物理学会春季学術講演会講演予稿集(CD-ROM)　70th　2023

ISSN： 2436-7613
Sub-pT magnetic field detection by tunnel magneto-resistive sensors

大兼幹彦, 大兼幹彦, 藤原耕輔, 菅野彰剛, 中野貴文, 我妻宏, 有本直, 水上成美, 水上成美, 熊谷静似, 松崎斉, 松崎斉, 中里信和, 安藤康夫, 安藤康夫

応用物理学会春季学術講演会講演予稿集(CD-ROM)　70th　2023

ISSN： 2436-7613
頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学(Web)　49　(5)　2021

ISSN： 2188-031X
TMRセンサの原理と心磁図計測

大兼幹彦, 大兼幹彦, 大兼幹彦, 菅野彰剛, 藤原耕輔, 中野貴文, 熊谷静似, 松崎斉, 中里信和, 安藤康夫

臨床神経生理学(Web)　49　(5)　2021

ISSN： 2188-031X
頭皮上に密着可能なトンネル磁気抵抗素子を用いた室温脳磁計の開発

菅野彰剛, 大兼幹彦, 藤原耕輔, 柿坂庸介, 松崎斉, 安藤康夫, 中里信和

臨床神経生理学(Web)　49　(5)　2021

ISSN： 2188-031X
Real-time magnetocardiographic measurement using tunnel magneto-resistive sensors

大兼幹彦, 菅野彰剛, 藤原耕輔, 松崎斉, 中里信和, 安藤康夫

日本生体医工学会大会プログラム・抄録集(Web)　60th　2021
Measurement of somatosensory evoked magnetic fields at room temperature using a tunnel magneto-resistive sensor system

菅野彰剛, 大兼幹彦, 藤原耕輔, 松崎斉, 安藤康夫, 中里信和

日本生体磁気学会誌　34　(1)　2021

ISSN： 0915-0374
研究室紹介 Invited

大兼幹彦

真空ジャーナル　9　2018/09
TMR磁気センサ Invited

大兼幹彦

まぐね　12　(5)　2017/12
Anisotropic magnetic property of nanocomposite Nd<inf>2</inf>Fe<inf>14</inf>B/Mo/α-Fe multilayer films

K. Kobayashi, D. Ogawa, K. Koike, H. Kato, M. Oogane, T. Miyazaki, Y. Ando, M. Itakura

Journal of Physics: Conference Series　903　2017/10/28

DOI： 10.1088/1742-6596/903/1/012015 　

ISSN： 1742-6588
Development of High-Resolution TMR Sensor Device for Application of Bio-Magnetic Field Measurement

212　33-38　2017/02/21
Publisher: 日本磁気学会
ISSN： 1882-2940
Systematic investigation on correlation between sensitivity and nonlinearity in magnetic tunnel junction for magnetic sensor.

T. Nakano, M. Oogane, H. Naganuma, Y. Ando

2015 IEEE MAGNETICS CONFERENCE (INTERMAG)　2015
界面装飾した強磁性トンネル接合の作製と磁気抵抗効果

安藤康夫, 大兼幹彦, 永沼博

東北大学極低温科学センターだより　(15)　3-6　2014/11
Publisher: 東北大学極低温科学センター
強磁性トンネル接合を用いた高感度生体磁気センサの開発

西川卓男, 藤原耕輔, 大兼幹彦, 永沼博, 中里信和, 安藤康夫

応用物理学会秋季学術講演会講演予稿集(CD-ROM)　74th　2013

ISSN： 2758-4704
Half-metallic Heusler alloys with low magnetic damping

OOGANE M, MIZUKAMI S, KUBOTA T, NAGANUMA H, ANDO Y

日本磁気学会研究会資料 = Bulletin of Topical Symposium of the Magnetics Society of Japan　183　21-24　2012/03/22
Publisher: 日本磁気学会
ISSN： 1882-2940
MgO障壁を用いたFePt垂直磁化トンネル磁気抵抗素子の磁気抵抗特性および極微構造

井波暢人, 永沼博, 金国天, 宮崎孝道, 佐藤和久, 今野豊彦, 大兼幹彦, 安藤康夫

日本磁気学会誌　34　(3)　293-296　2010/03
Publisher: 日本磁気学会
DOI： 10.3379/msjmag.1003R047 　

ISSN： 1882-2924

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Perpendicularly magnetized magnetic tunnel junctions (MTJs) were fabricated by depositing thin L1₀-ordered FePt films on MgO(001) substrates using a UHV sputtering system, and the dependence of structural, magnetic, and magnetotransport properties of the junctions on the thickness of the FePt layers was investigated. A full epitaxial structure of MgO(001) sub./Cr/Pt/FePt/MgO/CoPt/Ta was observed. The tunnel magnetoresistance (TMR) ratio was measured to be 6% at room temperature, and magnetization switching was clearly observed in the thin FePt layer. Transmission electron microscopy (TEM) observations revealed that the interface between FePt, MgO, and CoPt layer has strain due to lattice mismatch, which might be a reason for the low TMR ratio.
Optically induced magnetization dynamics and variation of damping parameter in epitaxial Co2MnSi Heusler alloy films

Y. Liu, L. R. Shelford, V. V. Kruglyak, Y. Sakuraba, M. Oogane, R. J. Hicken, Y. Ando

Physical Review B　81　(9)　094402　2010

DOI： 10.1103/PhysRevB.81.094402 　

ISSN： 1098-0121
Evidence of Fermi level control in a half-metallic Heusler compound Co2MnSi by Al-doping: Comparison of measurements with first-principles calculations

Y. Sakuraba, Y. Kota, T. Kubota, M. Oogane, A. Sakuma, Y. Ando, K. Takanashi

Physical Review B　81　(14)　144422　2010

DOI： 10.1103/PhysRevB.81.144422 　

ISSN： 1098-0121
26aVD-7 Time-resolved magneto-optical effect in perpendicularly magnetized Pt/Co/Pt trilayer films

Mizukami S., Sajitha E. P., Watanabe D., Wu F., Oogane M., Naganuma H., Ando Y., Miyazaki T.

Meeting abstracts of the Physical Society of Japan　64　(2)　360-360　2009/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Fe-Co-NiおよびCo基フルホイスラー合金薄膜における磁気緩和

水上成美, 大兼幹彦, 窪田嵩秀, 渡邉大輔, 永沼博, 安藤康夫, 宮崎照宣

日本磁気学会誌まぐね　4　(5)　229-235　2009/04
Spin dynamics in spin torque magnetization reversal

ANDO Y, AOKI T, TAMAGAWA T, WATANABE D, MIZUKAMI S, YAKATA S, TANIGUCHI T, IMAMURA H, NAGANUMA H, OOGANE M, INAMI N, MIYAZAKI T

Bulletin of Topical Symposium of the Magnetics Society of Japan　165　25-30　2009/03/13
Publisher: 日本磁気学会
ISSN： 1882-2940
27aTF-12 Optical detection of spin relaxation in films of magnetic metals

Mizukami S., Oogane M., Ando Y., Miyazaki T.

Meeting abstracts of the Physical Society of Japan　64　(1)　431-431　2009/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Generation of Spin Current by Spin Pumping and Physics Invited Peer-reviewed

Yasuo Ando, Shigemi Mizukami, Satoshi Yakata, Tomohiro Taniguchi, Hiroshi Imamura, Mikihiko Oogane, Terunobu Miyazaki

Magnetics Japan　4　(2)　73-81　2009/02
Publisher: 日本磁気学会
ISSN： 1880-7208
ホイスラー合金Co2MnSiを用いた高感度磁気抵抗素子の開発

桜庭裕弥, 岩瀬拓, 常木澄人, 斉藤今朝美, 大兼幹彦, 安藤康夫, 佐久間昭正, 高梨弘毅

IEICE Technical Report　(MR2008)　32　2008/11

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Development of high-sensitive magnetoresistance devices using half-metallic Heusler alloy Co2MnSi
Development of high-sensitive magnetoresistance devices using half-metallic Heusler alloy Co2MnSi

Y. Sakuraba, T. Iwase, S. Tsunegi, K. Saito, M. Oogane, Y. Ando, A. Sakuma, K. Takanashi

IEICE Technical Report MR　32　2008
Damping parameter of free layer material in MRAM measured by using ferromagnetic resonance

ANDO Y., OOGANE M., WATANABE D., WATANABE M., YILGIN R., YAKATA S., MIYAZAKI T.

153　7-14　2007/02/27

ISSN： 1340-7562
IETS法によるMgO-TMR膜のバリア構造観測

玉野井健, 大兼幹彦, 安藤康夫, 田中努, 上原裕二, 渦巻拓也

次世代磁気記録材料・システムへの挑戦　2007
MgOバリアTMR膜の電気伝導特性

玉野井健, 大兼幹彦, 安藤康夫, 田中努, 上原裕二, 渦巻拓也

日本応用磁気学会学術講演概要集　31st　2007

ISSN： 1340-8100
Magnetic damping constant of Co2FeSi Heusler alloy thin film

M. Oogane, R. Yilgin, Ma. Shinano, S. Yakata, Y. Sakuraba, Y. Ando, T. Miyazaki

Journal of Applied Physic　2007

DOI： 10.1063/1.2709751 　
New Magnetic Nano-Dot Memory with FePt Nano-Dots

YIN Cheng-Kuan, BEA Ji-Chel, MURUGESAN Mariappan, OOGANE Mikihiko, FUKUSHIMA Takafumi, TANAKA Tetsu, NATORI Kenji, MIYAO Masanobu, KOYANAGI Mitsumasa

2006　994-995　2006/09/13
Interfacial structure and half-metallic ferromagnetism in Co2MnSi-based magnetic tunnel junctions

N. D. Telling, P. Keatley, G. van, der Laan, R. J. Hicken, E. Arenholz, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

Physical Review B　74　(22)　224439　2006

DOI： 10.1103/PhysRevB.74.224439 　

ISSN： 1098-0121
Fabrication of Magnetic Tunnel Junction with Co2MnSi (110) Epitaxial Film

M. Hattori, Y. Sakuraba, M. Oogane, Y. Ando, T. Miyazaki

Journal of Magnetic Society of Japan　31　(2)　89-93　2006
Publisher: The Magnetics Society of Japan
DOI： 10.3379/jmsjmag.31.89 　

ISSN： 0285-0192

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According to Julliere's model, magnetic tunnel junctions (MTJs) with half-metallic electrodes lead to a large tunnel magnetoresistance (TMR) ratio. A Co₂MnSi Heusler alloy is theoretically expected to exhibit half-metallicity. We fabricated (110)-oriented epitaxial Co₂MnSi electrodes on sapphire substrates using W and Ta/W/Cr buffer layers. With the W buffer layer, we found that the W and Co₂MnSi layers formed a twin structure. However, with the Ta/W/Cr multi-buffer layers, we succeeded in fabricating a high-quality Co₂MnSi(110) epitaxial electrode. We fabricated a MTJ with the high-quality Co₂MnSi(110) electrode and investigated TMR effects in the MTJ. As a result, we observed a TMR ratio of about 40% at room temperature and 120% at 2 K.
24aXN-3 Spin injection in the superconductor and the magneto-resistance effect using ferromagnetic double tunneling junctions.

Daibo T., Oogane M., Ando Y., Miyazaki T.

Meeting abstracts of the Physical Society of Japan　60　(1)　407-407　2005/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
24aXN-1 Inelastic electron tunneling spectroscopy in Fe/MgO/Fe magnetic tunnel junctions

Miyakoshi T, Ando Y, Oogane M, Miyazaki T, Kubota H, Fukushima A, Nagahama T, Yuasa S

Meeting abstracts of the Physical Society of Japan　60　(1-3)　407-407　2005/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Tunnel Magnetoresistive Effect of Ferromagnetic Tunnel Junctions by Using Co_2MnAl Heusler Alloy

NAKATA J., OOGANE M., KUBOTA H., ANDO Y., KATO H., SAKUMA A., MIYAZAKI T.

28　395-395　2004/09/21
Fabrication of Co_2MnAl epitaxial films by using sputtering method

SAKURABA Y., NAKATA J., OOGANE M., KUBOTA H., ANDO Y., KATO H., SAKUMA A., MIYAZAKI T.

28　394-394　2004/09/21
Spin Injection into the Superconductor by Ferromagnetic Double Tunneling Junctions

DAIBOU T., OOGANE M., ANDO Y., MIYAZAKI T.

28　123-123　2004/09/21
Ferromagnetic tunnel junctions by using Co_2MnAl Heusler alloy

NAKATA J., OOGANE M., KUBOTA H., ANDO Y., KATO H., MIYAZAKI T.

27　266-266　2003/09/01

ISSN： 1340-8100
Fabrication dependence of Spin Polarization for Tunneling Electron

OOGANE M., DAIBOU T., KUBOTA H., ANDO Y., MIYAZAKI T.

27　434-434　2003/09/01

ISSN： 1340-8100
Tunnel magnetoresistance effect for ferromagneto// superconductor //ferromagmeto double tunnel junctions

DAIBOU T., OOGANE M., KUBOTA H., ANDO Y., MIYAZAKI T.

27　435-435　2003/09/01

ISSN： 1340-8100
Magnetic tunnel junction using an epitaxial Ni_<80>Fe_<20> thin film grown on a a single crystal Si substrate

YU J. H., LEE H. M., HAYASHI M., OOGANE M., KUBOTA H., ANDO Y., MIYAZAKI T.

26　10-10　2002/09/01

ISSN： 1340-8100
Tunneling conductance property for Al/Al-oxide/Ferromagnet junction

OOGANE M., DAIBOU T., KUBOTA H., ANDO Y., MIYAZAKI T.

26　9-9　2002/09/01

ISSN： 1340-8100
Magnetoresistance in Ce3Fe29-xTx (T = V and Cr)

XF Han, ZG Sun, H Kato, M Oogane, BG Shen, FM Yang, JMD Coey

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS　239　(1-3)　204-206　2002/02

DOI： 10.1016/S0304-8853(01)00558-3 　

ISSN： 0304-8853
Fabrication of magnetic tunnel junctions using epitaxial NiFe (111) ferromagnetic bottom electrodes

H. Yu, M. Hayashi, M. Oogane, H. Kubota, Y. Ando, T. Miyazaki, H. M. Lee

Appl. Phys. Lett　2002
Measurement of spin polarization using tunneling spectroscopy

OOGANE M., KUBOTA H., ANDO Y., MIYAZAKI T.

25　336-336　2001/09/01

ISSN： 1340-8100
Tunnel magnetoresistance effect for double junctions with superconductor middle layer

DAIBOU T., OOGANE M., KUBOTA H., ANDO Y., MIYAZAKI T.

25　344-344　2001/09/01

ISSN： 1340-8100
Oxidation Process of Insulator Layer in Ferromagnetic Tunnel Junction

HAYASHI M., ANDO Y., OOGANE M., KUBOTA H., MIYAZAKI T.

25　339-339　2001/09/01

ISSN： 1340-8100
Tunnel Magnetoresistance Effect for Double Tunnel Junctions with Superconducting Intermediate Layer

Daibou T., Oogane M., Ando Y., Kim C., Song O., Miyazaki T

Meeting abstracts of the Physical Society of Japan　56　(1)　711-711　2001/03/09
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Tunnel magnetoresistance effect for double junctions with Al middle layer

DAIBOU T., OOGANE M., ANDO Y., KIM Changkyung, SONG Ohsung, MIYAZAKI T.

24　52-52　2000/09/01

ISSN： 1340-8100
Transport properties in ferromagnetic double barrier junctions

SIRIPONGSAKUL T., OOGANE M., MURAI J., YU Andrew C. C., KUBOTA H., ANDO Y., MIYAZAKI T., KIM Changkyung, SONG Ohsung

24　51-51　2000/09/01

ISSN： 1340-8100
Measurement of Spin Polarization for Fe,Co,Ni using Tunneling Spectroscopy

Oogane M., Tezuka N., Kubota H., Ando Y., Miyazaki T.

Meeting abstracts of the Physical Society of Japan　55　(1)　410-410　2000/03/10
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Large anisotropic magnetoresistance in Ce_3Fe_<29-x>T_x(T=V and Cr)

HAN X. F., OOGANE M., MIYAZAKI T.

23　61-61　1999/10/01
26pPSA-45 Spin Polarization Measurement using Tunneling Spectroscopy

Oogane M, Tezuka N, Kubota H, Ando Y, Miyazaki T

Meeting abstracts of the Physical Society of Japan　54　(2)　419-419　1999/09/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Ni_<80>Fe_<20> Thickness Dependence of the TMR Ratio for Ni_<80>Fe_<20>/Al-Oxide/Co Junctions

OOGANE M., TEZUKA N., MIYAZAKI T.

Journal of Magnetics Society of Japan　23　(4)　1309-1312　1999/04/15
Publisher: 日本応用磁気学会
ISSN： 0285-0192

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Ferromagnetic tunneling junctions with various thicknesses of the first ferromagnetic layer were fabricated. Ni_<80>Fe_<20> and Co were used as the first ferromagnetic layer, and their thickness were varied between 10 and 200Å. The tunneling magnetoresistance (TMR) ratio decreased and the shape of the TMR curve changed with decreasing Ni_<80>Fe_<20> thickness, but changed only slightly with decreasing Co thickness. We calculated the TMR and magnetization curves by using a simple model that takes account of magnetic anisotropy to explain the change in the TMR ratio and the shape of the TMR curve with changing Ni_<80>Fe_<20> thickness.
28p-J-12 Voltage and Temperature Dependence of TMR Ratio for Co/Al-oxide/Co Junctions

Oogane M., Tezuka N., Miyazaki T.

Meeting abstracts of the Physical Society of Japan　54　(1)　412-412　1999/03/15
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
80NiFe Thickness Dependence of TMR ratio for 80NiFe/Al-oxide/Co Junctions

OOGANE M., TEZUKA N., MIYAZAKI T.

22　460-460　1998/09/01
Voltage and Temperature Dependence of TMR Effect for Ferromagnet/Al-oxide/Co Junctions

OOGANE M., TEZUKA N., MIYAZAKI T.

22　457-457　1998/09/01

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Books and Other Publications 6

スピントロニクスハンドブック : 基礎から応用まで

スピントロニクスハンドブック編集委員会, 佐橋, 政司, 湯浅, 新治, 遠藤, 哲郎

エヌ・ティー・エス　2023/05

ISBN: 9784860438425
Nanomagnetic materials : fabrication, characterization and application

Yamaguchi, Akinobu, Hirohata, Atsufumi, Stadler, J.H. Bethanie

Elsevier　2021

ISBN: 9780128223499
磁性材料・部品の最新開発事例と応用技術

大兼幹彦

技術情報協会　2018/03
新しい磁気センサとその応用

毛利佳年雄, 安藤康夫, 本蔵義信, 大兼幹彦, 内山剛, 野々村裕

2013
スピントロニクスの基礎と材料・応用技術の最前線

大兼幹彦, 宮崎照宣

2009
Epitaxial ferromagnetic metal films and spintronic applications

M. Oogane, T. Miyazaki

2008

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Presentations 55

室温⽣体磁場計測に向けたTMR センサ開発の進展 Invited

大兼幹彦

第40回日本生体磁気学会　2025/06/20
Highly sensitive spintronic Tunnel magneto-resistive sensor Invited

Mikihiko Oogane

Chicago-Tohoku Quantum Alliance workshop　2025/05/15
Ultra-sensitive tunnel magneto-resistive sensor Invited

Mikihiko Oogane

IcAUMS2025　2025/04/23
トンネル磁気抵抗センサを用いた室温生体磁場計測 Invited

大兼幹彦, 中里信和, 中野貴文, 石田誠, 藤原耕輔, 福島隼人, 熊谷静似, 松崎斉, 稲垣大

第39回日本生体磁気学会　2024/06/13
Development of ultra-sensitive spintronic sensor Invited

Mikihiko Oogane

Japan-Korea Spintronics Workshop　2024/05/31
量子スピントロニクスセンサの開発とユースケース開拓 Invited

大兼幹彦

第9回岩崎コンファレンス　2024/05/18
Introduction to the quantum startups from Tohoku Univ. Invited

Mikihiko Oogane

2024/02/14
トンネル磁気抵抗センサによる心磁・脳磁信号の室温計測 Invited

大兼幹彦

ヘルスケア・医療機器専門技術研究会　2024/01/31
量子スピンセンサ素子の開発およびユースケース開拓 Invited

大兼幹彦

科学技術と経済の会量子技術研究会　2024/01/15
Development of highly sensitive spintronic sensor Invited

2023/12/07
Development of highly sensitive tunnel magneto-resistive sensor Invited

5th Polish – Japanese Workshop on Spintronics　2023/11/14
Magnetic tunnel junctions designed for highly-sensitive magnetic sensor applications Invited

T. Nakano, K. Fujiwara, S. Kumagai, Y. Ando, M. Oogane

SPIE Spintronics XVI　2023/08/22
Development of TMR sensor for bio-magnetic field detection Invited

Mikihiko Oogane

ISACM and JBBS 2023 OSAKA　2023/05/25
Magnetic tunnel junction using soft magnetic CoFeSiB-based composite free layer for magnetic sensor applications Invited

T. Nakano, K. Fujiwara, S. Kumagai, Y. Ando, M. Oogane

iSIM 2023　2023/05/14
TMRセンサの開発とミニマルファブへの期待 Invited

大兼幹彦

ファブシステム研究会令和５年度リアル春季大会　2023/04/21
Spintronic sensor and its applications Invited

Mikihiko Oogane

2023/04/11
スピントロニクスセンサの開発と展望 Invited

大兼幹彦

電気学会ナノ磁性研究会　2023/03/31
TMRセンサによる生体磁場計測の進展 Invited

大兼幹彦, 藤原耕輔, 菅野彰剛, 中野貴文, 我妻宏, 有本直, 水上成美, 熊谷静似, 松﨑斉, 中里信和, 安藤康夫

第70回応用物理学会春季学術講演会　2023/03/18
トンネル磁気抵抗センサによるサブピコテスラ磁界検出 Invited

大兼幹彦, 藤原耕輔, 菅野彰剛, 中野貴文, 我妻宏, 有本直, 水上成美, 熊谷静似, 松﨑斉, 中里信和, 安藤康夫

第70回応用物理学会春季学術講演会　2023/03/17
TMR磁気センサの基礎と応用 Invited

大兼幹彦

2023年電子情報通信学会　2023/03/09
TMR磁気センサの高感度化技術と応用展開 Invited

大兼幹彦

第30回磁気応用技術シンポジウム　2022/08/23
スピントロニクスセンサの生体磁場計測応用 Invited

大兼幹彦

第37回日本生体磁気学会　2022/06/15
TMRセンサの高感度化の現状と今後の応用展開 Invited

大兼幹彦

センシング技術応用セミナー　2022/06/14
Measurement of Bio-magnetic Fields with Tunnel Magneto-resistive Sensors Invited

Mikihiko Oogane, Kosuke Fujiwara, Seiji Kumagai, Hitoshi Matsuzaki, Yasuo Ando

2022 Joint MMM-INTERMAG conference　2021/12/29
TMRセンサの原理と心磁図計測 Invited

大兼幹彦, 菅野彰剛, 藤原耕輔, 熊谷静似, 松﨑斉, 中里信和, 安藤康夫

第51回日本臨床神経生理学会学術大会　2021/12/16
Development of highly sensitive bio-magnetic TMR sensors Invited

Petaspin2021　2021/10/29
Development of highly sensitive TMR based sensor Invited

45th MSJ meeting　2021/09/02
Tunnel magneto-resistance effect in magnetic tunnel junctions International-presentation Invited

OOGANE Mikihiko

SSDM2018　2018/07/12
TMRセンサ材料および素子開発の進展 Invited

大兼幹彦

第68回スピンエレクトロニクス専門研究会　2018/07/06
Super-sensitive magnetic tunnel junction based sensor devices International-presentation Invited

OOGANE Mikihiko

NIMS special seminar　2018/05/16
Mnを含む強磁性規則合金のスピントロニクス応用 Invited

大兼幹彦

第184回スピニクス研究会　2017/07/28
スピンエレクトロニクス材料・デバイスの基礎 Invited

大兼幹彦

第40回日本磁気学会サマースクール　2017/06/09
強磁性トンネル接合を用いた高感度磁場センサ開発

第2回高周波スピントロニクス研究会　2016/02/22
スピントロニクスデバイス開発の最前線

SLiT-J Workshop　2016/01/19
Tunnel magneto resistance effect in MTJs with Mn-based ordered alloys International-presentation

The 13th RIEC International Workshop on Spintronics　2015/11/18
スピンエレクトロニクス材料・デバイスの基礎

第38回日本磁気学会サマースクール　2015/07/24
Fabrication of highly ordered Co2Fe0.4Mn0.6Si Heusler alloys on Si substrate

34rd Electronic Materials Symposium　2015/07/15
Highly ordered Co2Fe0.4Mn0.6Si Heusler alloy films for Spin-FET devices International-presentation

The 1st【ImPACT】International Symposium on Spintronic Memory, Circuit and Storage　2015/06/21
Perpendicularly magnetized L10-ordered alloys for magnetic tunnel junctions International-presentation

York-Tohoku-Kaiserslautern symposium　2015/06/11
Magnetic Tunnel Junctions with Amorphous CoFeSiB Free Layer for Highly Sensitive Magnetic Sensor Devices

33rd Electronic Materials Symposium　2014/07/09
スピンエレクトロニクス材料・デバイスの基礎

第37回日本磁気学会サマースクール　2014/07/08
Tunnel Magneto-resistance Effect in Magnetic Tunnel Junctions using Half-metallic Heusler Alloy Electrodes and a MgO Tunneling Barrier International-presentation

2008 MRS Fall Meeting　2008/12/02
Tunnel magnetoresistance effect in magnetic tunnel junctions with Co-Mn-Si Heusler alloy electrode International-presentation

53rd MMM conference　2008/11/12
フルホイスラー合金の磁気緩和定数測定

第69回応用物理学会学術講演会　2008/09/02
Magnetic damping constants in (CoFeB)Cr and (CoFeB)V alloy thin films International-presentation

52nd MMM　2007/11/05
ホイスラー合金の磁性とそれを用いたトンネル接合における磁気抵抗効果

第68回応用物理学会学術講演会　2007/09/06
Tunnel magneto resistance in MTJs with epitaxially grown Heusler alloy elecrodes International-presentation

M. Oogane, M. Hattori, Y. Sakuraba, Y. Ando, T. Miyazaki

ISAMMA2007　2007/05
Tunnel magnetoresistance effect in MTJs with Heusler alloy electrodes International-presentation

Workshop on Spin Current　2007/02/19
Tunnel magnetoresistance in MTJs with Co2MnSi electrode and MgO barrier International-presentation

M. Oogane, Y. Sakuraba, M. Hattori, Y. Ando, T. Miyazaki

The 2nd RIEC International Workshop on Spintronics, Sendai　2007/02/15
M. Oogane, R. Yilgin, M. Watanabe, S. Yakata, Y. Sakuraba, Y. Ando and T. Miyazaki International-presentation

M. Oogane, R. Yilgin, M. Watanabe, S. Yakata, Y. Sakuraba, Y. Ando, T. Miyazaki

10th Joint MMM/Intermag　2007/01
Gilbert Damping Constant in Co-Fe-B Films International-presentation

M. Oogane, M. Watanabe, S. Yakata, Y. Ando, T. Miyazaki

ICMFS2006　2006/08
Tunnel Magnetoresistance Effect in Co2XSi(X=Cr,Mn,Fe)/Al-O/CoFe Junctions International-presentation

M. Oogane, M. Shinano, R. Yilgin, Y. Sakuraba, H. Kubota, Y. Ando, A. Sakuma, T. Miyazaki

ICM2006　2006/08
ホイスラー合金の磁性と磁気伝導特性

大兼幹彦, 桜庭裕弥, R. Yilgin, 信濃正紹, 服部正志, 村上修一, 久保田均, 安藤康夫, 加藤宏朗, 佐久間昭正, 宮崎照宣

第12回スピンエレクトロニクス専門研究会　2006/07/24
Gilbert damping constants in various ferromagnetic thin films International-presentation

M. Oogane, T. Wakitani, S. Yakata, R. Yilgin, Y. Ando, A. Sakuma, T. Miyazaki

The 1st RIEC International Workshop on Spintronics, Sendai　2006/02/08
Gilbert Damping Constants in Ni-Co, Ni-Fe and Half-metallic Heusler Alloy Thin Films International-presentation

M. Oogane, T. Wakitani, S. Yakata, R. Yilgin, Y. Ando, A. Sakuma, T. Miyazaki

50thMMM　2004/11

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Industrial Property Rights 31

磁気センサ

小笠原貴大, 大兼幹彦, 角田匡清, 安藤康夫

特許第7440030号

Property Type: Patent
磁気抵抗素子の製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 関根孝二郎, 土田匡章

特許第7128476号

Property Type: Patent
磁気抵抗素子の製造方法

藤原耕輔, 安藤康夫, 大兼幹彦

特許第7128476号

Property Type: Patent
磁気センサ素子

大兼幹彦, 安藤康夫

特許第7106103号

Property Type: Patent
Mn系強磁性薄膜およびその製造方法、ならびにMn系強磁性薄膜を有する磁気トンネル接合素子

大兼幹彦, 安藤康夫, 栗本雄太, 渡部健太, 窪田美穂

特許第6985708号

Property Type: Patent
トンネル磁気抵抗素子の製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一

特許第6978000号

Property Type: Patent
トンネル磁気抵抗素子の製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一

特許第6978000号

Property Type: Patent
トンネル磁気抵抗素子及び磁化方向補正回路

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 寺内孝, 関根孝二郎, 土田匡章

特許第6969751号

Property Type: Patent
トンネル磁気抵抗素子の製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 関根孝二郎, 城野純一, 土田匡章

特許第6969752号

Property Type: Patent
トンネル磁気抵抗素子及び磁化方向補正回路

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 寺内孝, 関根孝二郎, 土田匡章

特許第6969751号

Property Type: Patent
トンネル磁気抵抗素子及びその製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 土田匡章

特許第6923881号

Property Type: Patent
トンネル磁気抵抗素子及びその製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 土田匡章

特許第6923881号

Property Type: Patent
Mn系強磁性薄膜の製造方法およびMn系強磁性薄膜

大兼幹彦, 安藤康夫, 渡部健太

特許第6870850号

Property Type: Patent
磁気センサ

小笠原貴大, 大兼幹彦, 角田匡清, 安藤康夫

特許第6702034号

Property Type: Patent
磁気センサ

古市喬干, 青建一, 安藤康夫, 大兼幹彦, 中野貴文

特許第6702034号

Property Type: Patent
トンネル磁気抵抗素子及び磁化方向補正回路

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 寺内孝, 関根孝二郎, 土田匡章

Property Type: Patent
磁気抵抗素子及び磁気抵抗素子の製造方法

安藤康夫, 大兼幹彦, 藤原耕輔, 城野純一, 関根孝二郎, 土田匡章

Property Type: Patent
FeSiAl合金薄膜およびFeSiAl合金薄膜の製造方法、ならびに、磁気センサおよび磁気センサの製造方法

大兼幹彦, 赤松昇馬, 安藤康夫, 熊谷静似

Property Type: Patent
FeSiAl合金薄膜およびFeSiAl合金薄膜の製造方法、ならびに、磁気センサおよび磁気センサの製造方法

大兼幹彦, 赤松昇馬, 安藤康夫, 熊谷静似

Property Type: Patent
磁気センサ

小笠原貴大, 大兼幹彦, 角田匡清, 安藤康夫

Property Type: Patent
磁気センサ

藤原耕輔, 熊谷静似, 大兼幹彦, 安藤康夫

Property Type: Patent
磁気センサおよびその製造方法

古市喬干, 吉村政洋, 阿部竜一郎, 与倉久則, 薬師寺啓, 杉原敦, 福島章雄, 湯浅新治, 大兼幹彦, 安藤康夫, 角田匡清

Property Type: Patent
トンネル磁気抵抗素子およびトンネル磁気抵抗センサ

藤原耕輔, 熊谷静似, 安藤康夫, 大兼幹彦

Property Type: Patent
トンネル磁気抵抗センサ

サブリチャキル, 藤原耕輔, 熊谷静似, 安藤康夫, 大兼幹彦

Property Type: Patent
磁気センサ装置およびその製造方法

古市喬干, 阿部竜一郎, 与倉久則, 安藤康夫, 大兼幹彦, 薬師寺啓, 杉原敦, 久保田均, 福島章雄

Property Type: Patent
トンネル磁気抵抗センサおよびその製造方法

中野貴文, 藤原耕輔, 熊谷静似, 松﨑斉, 安藤康夫, 大兼幹彦

Property Type: Patent
ＦｅＳｉＡｌ合金薄膜およびＦｅＳｉＡｌ合金薄膜の製造方法、ならびに、磁気センサおよび磁気センサの製造方法

大兼幹彦, 赤松昇馬, 安藤康夫, 熊谷静似

Property Type: Patent
磁化率測定装置及び磁化率測定方法

アルマダウィミフタ, 大兼幹彦

Property Type: Patent
検査装置、検査方法及び検査プログラム

伊藤淳, 大兼幹彦

Property Type: Patent
磁気センサー加工方法

藤原耕輔, 安藤康夫, 大兼幹彦

Property Type: Patent
トンネル磁気抵抗素子と磁化方向補正回路

藤原耕輔, 安藤康夫, 大兼幹彦

Property Type: Patent

Show all Show first 5

Research Projects 26

量子スピンセンサを利用した海中における革新的磁気センシング技術の開発

System: JST 経済安全保障重要技術育成プログラム

Institution: 東北大学

2024 - 2029/03
量子スピンセンサの開発とユースケースの開拓・実証

System: SIP第３期「先進的量子技術基盤の社会課題への応用促進」

Institution: 東北大学

2023/12 - 2028/03
Development of anomalous Hall effect materials with high spin polarization for high efficiency spin-orbit-torque magnetization switching

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2024/04/01 - 2027/03/31
超小型スピントロニクス量子磁力計の創成

大兼幹彦

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2024/04/01 - 2027/03/31
量子スピンセンサのμモジュール化による新規ユースケースの創出

System: 研究開発とSociety5.0との橋渡しプログラム（BRIDGE）

Institution: 東北大学

2024/10 - 2027/03
人協働ロボット向高精度電流センサの多品種少量生産のための超高真空多元ミニマルスパッタ装置の開発

System: 成長型中小企業等研究開発支援事業

Institution: ナバテック、三重大学、東北大学

2024 - 2027/03
音波を使用した液中非破壊検査

Offer Organization: 日本学術振興会

System: 科学研究費補助金

Category: 基盤研究（C）

Institution: 東北大学

2023/04 - 2026/03
Sensoron: Fusing Memory and Computing into Spintronics-based Sensors

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2022/04/01 - 2025/03/31
スピントロニクスセンサによる低周波電磁波を活用したスマートインフラ検査技術の開発

Offer Organization: 総務省

System: SCOPE

Institution: 東北大学、コニカミノルタ、スピンセンシングファクトリー

2023/06 - 2025/03
常温稼働可能な磁気顕微鏡開発と資源科学・地球惑星科学への応用

System: 東北大学－産総研マッチング研究支援事業

Institution: 東北大学、産総研

2024 -
Development of TMR sensor

2024 -
量子スピントロニクス脳磁計の開発

大兼幹彦

Offer Organization: NEDO

System: 先導研究プロジェクト

Institution: 東北大学

2022/05 - 2023/03
高感度磁気センサの研究開発

Institution: ソニーセミコンダクタ、スピンセンシングファクトリー、東北大学

2023/01 -
Variety of physical properties of hetero-junction with ordered alloys and the spin devices

ANDO Yasuo, MIZUKAMI Shigemi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

Category: Grant-in-Aid for Scientific Research (S)

Institution: Tohoku University

2012/05/31 - 2017/03/31

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L10 structure MnAl thin film with large magnetic anisotropy, small magnetic relaxation constant and good flatness was succeeded in producing. A CoFeMnSi Heusler alloy exhibiting high spin polarizability and small magnetic relaxation constant could be fabricated on an amorphous SiO2 substrate. By inserting an ultra-thin Pd thin film on the L10 - FePd electrode and optimizing the deposition temperature, it was possible to fabricate a tunnel insulating layer epitaxially grown. We succeeded to fabricate ultra-thin and high quality Bi ferrite thin film on LaSrMnO3 ferromagnetic layer. Since the heterojunction using the ordered alloy as described above exceeds the performance of the conventional spin device and shows various physical phenomena, it leads to the creation of a completely new spin device.
Development of the magneto-resistive devices with high-output and low-power-consumption using L10/Heusler electrodes

OOGANE MIKIHIKO

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2012/04/01 - 2015/03/31

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We have fabricated L10-ordered Mn-based perpendicular magnetized ferromagnetic films with high magnetic anisotropy and low magnetic damping constant. Magnetic tunnel junctions (MTJs) with the multi-layer electrodes of Mn-based alloys and ferromagnetic films or Heusler alloys were fabricated. We have successfully observed tunnel magnetoresistance effect in the fabricated MTJs. In addition, very high MR ratio of 80% was observed at RT and spin-transfer-switching was also observed in CPP-GMR devices with Heusler alloy electrodes. These results indicate that developed devices are very useful in future spintronics field.
Magnetic damping control of ferromagnetic thin films with negative spin polarization and development of highly efficient spin-current generator

ISOGAMI Shinji, TSUNODA Masakiyo, OOGANE Mikihiko, SAKUMA Akimasa

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

Category: Grant-in-Aid for Young Scientists (B)

Institution: Fukushima National College of Technology

2012/04/01 - 2015/03/31

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Highly efficient spin-current generator was developed using Fe4N thin films with negative spin polarization. The high quality Fe4N/Pt bilayer films were fabricated by the reactive sputtering with Ar and N2 gas mixture during thermal treatment using the focused IR heating system. The electromotive force due to inverse spin-Hall effect generated by spin-pumping from the Fe4N films exhibited one order larger value, compared with the NiFe conventional films. The results implied that our developed Fe4N/Pt systems provided highly spin-current generator.
ハーフメタル合金素子作製のための超高真空加熱・成膜制御システムの開発

大兼幹彦

System: 産学が連携した研究開発成果の展開復興促進プログラム A-STEP シーズ顕在化タイプ

Institution: アルバックテクノ株式会社

2012 - 2013
Fabrication of perpendicular magnetized tunnel junction and magnetization reversal by spin injection

MIYAZAKI Terunobu, MIZUKAMI Shigemi, OOGANE Mikihiko

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2009 - 2011

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In order to develop a memory cell material which is applicable to high density magnetic random access memory (MRAM), the composition dependence on saturation magnetization Ms, perpendicular magnetic anisotropy constant Ku and Gilbert damping constant . have been investigated in epitaxial Mn_xGa_<1-x> (0. 5≦x≦0. 75)alloy films. The M_s values decrease linearly from approximately 600 to 200 emu/cc with increasing x, where as the K_u values decrease slightly from 15 to 10 Merg/cc with increasing x. The damping constant . is 0. 08 (0. 015)for Mn_<1. 54> Ga (Mn_<2. 12> Ga)film. These magnetic properties satisfy the requirement for memory cell. Furthermore, by using Mn-Ga alloy films as the electrode of tunnel junction, we investigated the magnetoresistance ratio at 10 K and 300 K. With an insertion of Fe (Co)between Mn-Ga electrode and tunnel barrier the maximum TMR value up to 60 (40)%is obtained at room temperature. An increase of TMR value is necessary for MRAM memory cell.
Spin wave excitation in metallic nano-hetero structures and fabrication of high frequency devices

ANDO Yasuo, OOGANE Mikihiko, MIZUKAMI Shigemi, NAGANUMA Hiroshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2008 - 2010

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Current-Perpendicular-to-Plane Giant Magnetoresistance (CPP-GMR)nano-hetero devices with bottom free layers were fabricated on Si substrates and the spin-transfer-torque-induced rf oscillation was measured. The intensity of the oscillation became large and the half width reduced when the magnetic field was applied 90° from the easy axis and the current was between 3 mA and 7 mA. Also, a pseudo-point-contact GMR device on a coplanar waveguide with low high-frequency loss was fabricated. The high-frequency loss was reduced by 10%.
Optical detection of spin current and magnetization relaxation in metallic multilayers

ANDO Yasuo, OOGANE Mikihiko, MIZUKAMI Shigemi, NAGANUMA Hiroshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas

Category: Grant-in-Aid for Scientific Research on Priority Areas

Institution: Tohoku University

2007 - 2010

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We investigated ultrafast demagnetization for epitaxial Heusler films using an all-optical pump-probe technique. Values of demagnetizationτM increased with the laser power P for Mn-Ga alloys and perpendicular magnetized Co-alloys, this is consistent with microscopic theory. On the other hand,τM decreased with P for Co_2MnSi Heusler alloys on Ag and Cr buffer layers.
超微小サイズ不揮発性MRAM素子の性能評価

大兼幹彦

System: 産学が連携した研究開発成果の展開研究成果展開事業地域事業地域イノベーション創出総合支援事業シーズ発掘試験

Institution: 東北大学

2009 - 2009

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大容量・高速・低消費電力動作が可能な不揮発性磁気ランダムアクセスメモリ(MRAM)のサイズ限界は、磁化の熱揺らぎ限界に起因し、CoPtのような高磁気異方性材料では数nm幅程度である。本研究では、直径が数nm程度のCoPtナノドットをCoPt/MgO層上に成長させ、1つのナノドットがトンネル磁気抵抗素子に対応する超微小MRAM素子を作製し、その特性を伝導性原子間力顕微鏡により評価する。
Development of the half-metal spin switch and its application tothe logic circuit

OOGANE Mikihiko

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)

Category: Grant-in-Aid for Young Scientists (A)

Institution: Tohoku University

2008 - 2009

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Magnetic tunnel junctions (MTJs) with Co_2MnSi based half-metallic Heusler alloy electrodes and an MgO barrier showed very large tunnel magneto resistance (TMR) ratio of 1275% at low temperature and 350% at room temperature. This TMR ratio is the highest among the MTJs with Heusler alloy electrodes. The large TMR effect is desirable for application to the spin-switch device. In addition, the TMR ratio was successfully controlled by the voltage in the device that two MTJs were connected in series. This result indicates that the fabricated device can be used as the logic circuit.
ハーフメタル・ナノスピントランジスタの開発

大兼幹彦

Offer Organization: 日本学術振興会

System: 科学研究費助成事業若手研究(B)

Category: 若手研究(B)

Institution: 東北大学

2006 - 2007

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1.ホイスラ合金を用いた高TMR素子の作製これまでは,アモルファス構造のA1-Oを絶縁層として用いていたが,今年度は,結晶質のMgOを絶縁層に用いたCo_2MnSi/MgO/CoFe-TMR素子において,前年度を上回る,217%(室温),753%(低温)のTMR比を観測することに成功した.観測したTMR比はホイスラー合金を電極に用いたTMR素子において世界最高の値である.また,コンダクタンス特性の測定結果から,コヒーレントトンネリングが巨大TMR比の起源であることが示唆された。 2.ハーフメタル・スピントランジスタへの微細加工作製したCo_2MnSi/MgO/Co_2MnSiTMR素子を前年度に確立した微細加工プロセスを用いてトランジスタ形状に微細加工した.加工後のTMR比は低温で270%であり,加工によるダメージがほとんどないことが分かった.さらに,ゲート電圧を印加して,ソース-ドレイン間の電流-電圧特性を測定した結果,ハーフメタルギャップエネルギー(〜150mV)以上のゲート電圧を加えると,ソース・ドレイン電流が大きく変化する現象が観測された.この動作は,考案当初に期待していたものと同様であり,ハーフメタルを用いたスピントランジスタ動作を初めて実証したものである. 3.ハーフメタル・スピントランジスタの高性能化のためのホイスラー合金材料探索これまでに開発を行なってきたCo_2MnSi組成に加えて,今年度は,Co_2FeSi,Co_2CrSiの開発を行なった.その結果,前年度まで開発を進めていたCo_2MnSiを用いたTMR素子が最も高性能であることを明らかにした.
Development of magnetic tunnel junctions using Heusler alloy and observation of spin-injected magnetization reversal

MIYAZAKI Terunobu, ANDO Yasuo, KUBOTA Hitoshi, MIZUKAMI Shigemi, OOGANE Mikihiko

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2005 - 2007

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1. Fabrication of magnetic tunnel junctions using epitaxial Heusler alooy electrodes Large tunnel magneto-resistance (TMR) ratios of 217% at room temperature and 753% at low temperature have been successfully observed in a magnetic tunnel junction (MTJ) using a high quality Heusler alloy electrode and an MgO crystalline barrier. The structure of the MTJ was Co2MnSi/MgO/CoFe. This observed TMR ratio is highest among the MTJs using Heusler alloy electrodes. Moreover, conductance-voltage property of the MTJ investigated in detail indicates that the origin of the large TMR was coherent tunneling process through the crystalline MgO barrier. 2. Micro-fabrication of MTJs and Observation of spin-injected magnetization reversal Spin-injected magnetization reversal has been successfully observed in the micro-fabricated CoFeB/MgO/CoFeB-MTJs using (Co_<50>Fe_<50>)_<100-x>B_x (x=20, 25, 30, thickness d=2 nm) switching layers. We found from this result that the switching current density depended on magnetization, damping constant and spin polarization of the ferromagnetic layer as expected by theory and reducing of magnetization and damping constant was quite effective to decrease the switching current density. 3. Magnetic damping constant α Magnetic damping constants in various ferromagnetic thin films were investigated systematically by FMR technique. Moreover, a measurement technique for estimation of damping constants in MTJs has been established. As a result, we found that the damping constant of 2nm thick CoFeB film was five times larger than that of bulk CoFeB and the neighboring layer of the switching layer influence the damping constant of the switching layer.
Spin dynamics in small magnetic tunnel junctions

OOGANE Mikihiko, KUBOTA Hitoshi, MIZUKAMI Shigemi, MIYAZAKI Terunobu

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2003 - 2005

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1. Spin injection into nano-area by using micro-fabrication technique (1) Small magnetic tunnel junctions (MTJs) with MgO barrier were fabricated by using focused ion beam (FIB) and electron beam lithography. The minimum size was 100 x 200nm^2 and the resistance x area product of 6Ωμm^2 and the tunnel magnetoresistance (TMR) ratio of 90% were obtained. (2) Spin injection magnetization reversal was successfully observed for the MTJs. The current density was 7.7 x 10^6A/cm^2 and the density increased with increasing the annealing temperature. 2. Spin relaxation at the interface of junctions (1) Ferromagnetic resonance (FMR) spectra were measured for Ferromagnet (FeNi)/Nonmagnet (Cu,Ru,Pt) and FeNi/Cu/Pt multilayers and spin relaxation time and spin diffusion length were estimated from the FMR line width. The spin diffusion length of Cu was approximately 350nm and 1000nm at room temperature and liquid He temperature, respectively. (2) FMR spectra were measured for Ferromagnet(FM)/Cu/CoFe multilayers and the increasing ratio of FMR linewidth for the FM was measured. In case of CoFeB as the FM, the linewidth of CoFe increased, on the other hand, the increaseng ratio of CoFeB was small. 3. Measurement of response signal by a fast pulse field from a coplanar line (1) For the electrical detection of the spin injection magnetization reversal, a homemade probing apparatus (the pulse width : 1μs, the maximum pulse current : 20mA) was set up. The reversal current depending on the pulse width was measured. The current increased with reducing the pulse width. (2) Pump-probe measurement system was set up in order to measure the spin dynamics in the time scale less than 500ps. The precession signal of permaloy of the size of 180μm x 90μm was measured and the damping parameter α of 0.008 was obtained. (3) The damping parameter of synthetic ferrimagnet was larger than that of FeNi single layer film.
スピンエレクトロニクス材料探索およびデバイス作製技術開発 Competitive

1998/04 -

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Teaching Experience 10

電磁気学II
物性物理学原論
先端スピン工学特論
ナノ構造制御工学
磁性物理学
学問論演習
学生実験
物理学A
界面物理学
電磁気学I

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Other 25

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

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スピントロニクス学術研究基盤と連携ネットワークの構築
学際研究重点プログラム

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原子内包フラーレンナノバイオトロニクスの創成
ＴＭＲ素子のセンサ応用研究

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リニア出力型ＴＭＲ磁気センサの研究 ‐ 垂直磁場印加型構造の出力リニアリティとダイナミックレンジの特性検証 -
低RA・高スピン偏極ソース/ドレイン電極の開発

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スピンFET実現のための低RA・高スピン偏極ソース/ドレイン電極を開発する
JSPS Core-to-Coreプロジェクト

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次世代スピントロニクス素子の作製と評価
産学コンソーシアム運営事業

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強磁性トンネル接合素子を用いた高感度磁気センサの研究開発
文部科学省次世代IT基盤構築のための研究開発

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耐災害性に優れた安心・安全社会のためのスピントロニクス材料およびデバイス基盤技術の研究開発を行う
JST復興促進プログラム（Ａ－ＳＴＥＰ）ハーフメタル合金薄膜作製のための超高真空加熱・成膜制御システムの開発

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ハーフメタル合金は、電気伝導を担う電子スピンが完全にスピン偏極することが期待され、スピントロニクス分野において非常に大きな注目を集めている。特に、東北大学の大兼准教授のグループでは、ハーフメタル合金薄膜を利用した、高品位なスピントロニクス素子の開発に成功しており、磁気メモリ、HDDヘッド、生体磁気センサー、スピントランジスタ等の画期的素子への応用が期待されている。しかし、現在の素子作製プロセスは、良質な素子を作製可能である反面、生産プロセスに適合したものではない。本提案は、ハーフメタルを用いた素子を製品化するために必要不可欠な、短時間で高品位な素子を得るための超高真空加熱・成膜制御システムを開発することを目的としたものである。
トンネル磁気抵抗素子を用いた心磁図および脳磁図と核磁気共鳴像の室温同時測定装置の開発

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強磁性トンネル接合を用いた微小モジュールを配置した室温動作の脳磁計、心磁計の開発
JST産学共創基礎基盤研究プログラム

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高品位モデル磁石の高精度磁気特性および構造評価
ハーフメタルホイスラー合金を用いた巨大磁気抵抗素子における磁気抵抗効果の結晶面方位依存性に関する研究

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次世代のハードディスク用読み取りヘッドとして、高磁気抵抗比と低素子抵抗値を兼ね備えた、面直通電型巨大磁気抵抗 (CPP-GMR) 素子に対する期待が大きい。伝導電子が完全にスピン分極したハーフメタル材料をCPP-GMR素子の電極に用いれば、飛躍的に磁気抵抗比を向上させることが原理的に可能である。本研究では、ハーフメタル材料としてホイスラー合金を用い、種々の結晶面方位を有するフルエピタキシャルCPP-GMR素子を開発する。結晶面方位と磁気抵抗効果の関係を明らかにし、70～100%の高磁気抵抗比を実現するための明確な指針を得ることが本研究の目的である。
先端スピントロニクス材料と伝導現象(ASPIMATT)

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新材料によりもたらされる新規の伝導現象を実現することを主目的とし、新材料を用いたトンネル磁気抵抗（TMR）素子および巨大磁気抵抗（GMR）素子に加えて、ローカル／ノンローカル面内スピン伝導、スピンホール効果およびマグノンによる角運動量伝導のような新しいタイプのスピントロニクスデバイスの創成を目指す。
最先端研究開発支援プログラム

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省エネルギー・スピントロ二クス論理集積回路の研究開発
Design of Materials and Structures for Reduction in Spin Transfer Noise for Heusler Alloy Based CPP GMR Structures

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ホイスラー合金を用いたHDD用CPP-GMR素子の作製と評価に関する研究
超微小サイズ不揮発性MRAM素子の性能評価

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CoPt微粒子を磁化反転層とした超微少MRAM素子を作製し，伝導性AFM装置を用いてその評価を行なう研究で，提案研究とは全く異なる。
二国間交流事業

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日本-中国の二国間で強磁性トンネル接合および二重強磁性トンネル接合の開発を行なう。
巨大トンネル磁気抵抗素子を用いた超高感度磁界センサーの開発

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巨大な磁気抵抗効果を示すトンネル接合素子を超高感度な磁界センサーに応用する研究である。磁界センサーの性能を示す，単位磁界あたりの抵抗変化率が20%/Oe以上の高性能トンネル接合を作製し，磁界センサー回路を試作する。本事業期間中にナノテスラオーダーの磁界検出を実証し，製品化に向けた研究開発へと向かう。さらに，超伝導量子干渉素子 (SQUID) クラスの超高感度磁界検出の実現可能性を明らかにする。
数Tbit/inch2磁気記録密度実現のためのオールホイスラー合金磁気抵抗素子の開発

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非磁性のホイスラー合金を中間層とした面直通電型GMR素子を作製し，磁気ヘッドへの応用を目指すものである。本提案の超高感度センサーと異なり，比較的低感度であっても，ヘッドの回路に適合する極めて低抵抗のGMR素子を作製するための研究である。
JST 戦略的国際科学協力推進事業高スピン分極率を有するホイスラー合金に関する研究

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日本側の優れたホイスラー合金作製技術とドイツ側の高度なスピンダイナミクス測定技術を融合し，新たな物理現象，デバイスを創出する為の研究
文部科学省高機能・超低消費電力スピンデバイス・ストレージ基盤技術の開発

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世界をリードするナノスピン材料創成・磁性体極微細加工技術の研究開発を基軸に，スピンデバイスを活用する革新的な高速・不揮発性メモリインロジック（電力/速度比1/1000以下）とテラビット級次世代垂直記録技術による超高速大容量ストレージシステム（電力/容量比1/20以下，どちらも従来技術の延長と比較）を開発し，次世代の高機能・超低消費電力コンピューティングデバイス・システムの基盤技術を確立する．
NEDO スピントロニクス不揮発性機能技術プロジェクト

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スピントロニクス技術が秘める不揮発性機能をはじめとする情報通信分野における革新的諸機能を実現するための基盤技術の確立、並びに、実用化に向けたデバイス技術の研究開発
次世代スピンデバイス創生のためのハーフメタル強磁性トンネル接合の開発

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電子の電荷とスピンの二つの自由度を積極的に利用する”スピンエレクトロニクス”が、次世代情報化社会の中で果たす役割は非常に大きい。不揮発性磁気メモリ(MRAM)を始めとして、スピンデバイスの研究開発は急速に進展しており、また、次世代の全く新しいスピンデバイスも種々考案されている。それぞれのスピンデバイスに求められる材料、素子特性はデバイスごとに異なるが、あらゆるスピンデバイスに共通して求められるものは、”高スピン分極率を有する強磁性体材料”である。本研究では、ハーフメタル強磁性体 (スピン分極率100 %) である”ホイスラー合金材料”の開発を行い、それを用いた”巨大なトンネル磁気抵抗比を示す素子”作製技術の確立を目指す。
共鳴磁気トンネル・ナノドット不揮発性メモリの創製

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本研究は、代表者が提案した共鳴磁気トンネル・ナノドット不揮発性メモリを実現し、その動作を確認し、それを用いた新しいメモリ回路の可能性を示すことを目的としている。SAND 法と呼ぶ新しい膜形成手法を用いて、ドット粒径が1～3nm で、従来より約1 桁高いドット密度（2×1013cm-2）をもつFePt ナノドットの形成に成功した。また、FePt ナノドットを浮遊ゲートとするMOS構造を用いて磁気トンネル・ナノドット不揮発性メモリの基本的な動作の確認にも成功している。
総務省SCOOPプログラム超ギガビット磁気メモリの基盤技術の開発

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超大容量磁気ランダムアクセスメモリ(MRAM)のための高性能材料の開発
RR2002 ITプログラム高機能・超低消費電力メモリの開発

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大容量，高速，低消費電力の磁気ランダムアクセスメモリ(MRAM)の開発

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