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Masako Suzuki

Section

Graduate School of Engineering

Job title

Associate Professor

Degree

Doctor(Science)

researchmap

https://researchmap.jp/masakosk

J-GLOBAL ID

201201059560162012

e-Rad No.

90598880

ORCID

https://orcid.org/0000-0002-2950-4347

Research History 4

2025/11 - Present

Tohoku University　Graduate School of Engineering　Associate Professor
2018/10 - 2026/03

Gunma University　Graduate School of Science and Technology　Associate Professor
2014/09 - 2018/09

High Energy Research Organization　Institute of Materials Structure Science　Assistant Professor
2009/10 - 2014/08

High Energy Research Organization　Institute of Materials Structure Science　Assistant Professor

Education 3

Chiba University　Graduate School of Advanced Integration Science

2007/04 - 2009/09
Chiba University　Graduate School of Natural Science

2005/04 - 2007/03
Chiba University　Faculty of Science

2001/04 - 2005/03

Professional Memberships 5

THE JAPANESE SOCIETY FOR SYNCHROTRON RADIATION RESEARCH
THE PHYSICAL SOCIETY OF JAPAN
THE JAPAN SOCIETY OF APPLIED PHYSICS
日本XAFS研究会
日本表面真空学会

Research Interests 3

XMCD
XAFS
Magnetic thin films

Research Areas 2

Natural sciences / Semiconductors, optical and atomic physics /
Nanotechnology/Materials / Thin-film surfaces and interfaces /

Papers 74

Expert-guided background processing framework for depth-resolved X-ray magnetic circular dichroism analysis

Haruto Yokoyama, Kenta Amemiya, Hiroshi Naganuma, Masako Suzuki-Sakamaki

Japanese Journal of Applied Physics　2025/10/01

DOI： 10.35848/1347-4065/ae10f3 　
Relationship between orbital moment anisotropy, magnetocrystalline anisotropy, and Dzyaloshinskii-Moriya interaction in W/Co/Pt trilayers

Zhendong Chi, Yong-Chang Lau, Vanessa Li Zhang, Goro Shibata, Shoya Sakamoto, Yosuke Nonaka, Keisuke Ikeda, Yuxuan Wan, Masahiro Suzuki, Masashi Kawaguchi, Masako Suzuki-Sakamaki, Kenta Amemiya, Naomi Kawamura, Masaichiro Mizumaki, Motohiro Suzuki, Hyunsoo Yang, Masamitsu Hayashi, Atsushi Fujimori

Physical Review B　110　(18)　2024/11/07
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevb.110.184401 　

ISSN： 2469-9950

eISSN： 2469-9969

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We have studied the Co layer thickness dependences of magnetocrystalline anisotropy (MCA), Dzyaloshinskii-Moriya interaction (DMI), and orbital moment anisotropy (OMA) in W/Co/Pt trilayers, in order to clarify their correlations with each other. We find that the MCA favors magnetization along the film normal and monotonically increases with decreasing effective magnetic layer thickness (teff). The magnitude of the Dzyaloshinskii-Moriya exchange constant (|D|) increases with decreasing teff until teff∼1 nm, below which |D| decreases. The MCA and |D| scale with 1/teff for teff larger than ∼1 nm, indicating an interfacial origin. The increase of MCA with decreasing teff continues below teff∼ 1 nm, but with a slower rate. To clarify the cause of the teff dependences of MCA and DMI, the OMA of Co in W/Co/Pt trilayers is studied using x-ray magnetic circular dichroism. We find nonzero OMA when teff is smaller than ∼0.8 nm. The OMA increases with decreasing teff more rapidly than what is expected from the MCA, indicating that factors other than OMA contribute to the MCA at small teff. The teff dependence of the OMA also suggests that |D| at teff smaller than ∼1 nm is not related to the OMA at the interface. We propose that the growth of Co on W results in a strain and/or texture that reduces the interfacial DMI, and, to some extent, MCA at small teff. Published by the American Physical Society 2024
Development of a Hemispherical Cavity Cobalt Electrocatalyst for Water Oxidation Based on a Polystyrene Colloidal Template Electrodeposition Method

Yusaku Araki, Shun Tsunekawa, Arisu Sakai, Kazuki Harada, Ryosuke Nagatsuka, Masako Suzuki‐Sakamaki, Kenta Amemiya, Ke‐Hsuan Wang, Takeshi Kawai, Masaaki Yoshida

ChemistrySelect　7　(29)　2022/08/05
Publisher: Wiley
DOI： 10.1002/slct.202200600 　

ISSN： 2365-6549

eISSN： 2365-6549
Development of Fluorescence-yield Wavelength-dispersive Soft X-ray Absorption Spectroscopy for Real-time Observation of Surface Chemical Reaction Peer-reviewed

Kenta Amemiya, Kaoruho Sakata, Masako Suzuki-Sakamaki

e-Journal of Surface Science and Nanotechnology　20　2022/05/28
Publisher: Surface Science Society Japan
DOI： 10.1380/ejssnt.2022-020 　

ISSN： 1348-0391

eISSN： 1348-0391
Three-dimensional chemical-state imaging with reflection-mode soft x-ray absorption spectroscopy Peer-reviewed

M. Suzuki-Sakamaki, K. Amemiya

Review of Scientific Instruments　92　(12)　123702-1-123702-5　2021/12/01
Publisher: AIP Publishing
DOI： 10.1063/5.0069096 　

ISSN： 0034-6748

eISSN： 1089-7623
Real-Time Observation of Surface Chemical Reactions Proceeding in the Depth Direction by Wavelength-Dispersive Soft X-ray Absorption Spectroscopy Peer-reviewed

Kaoruho Sakata, Masako Suzuki-Sakamaki, Kenta Amemiya

Nano Letters　21　(17)　7152-7158　2021

DOI： 10.1021/acs.nanolett.1c01783 　

ISSN： 1530-6984

eISSN： 1530-6992
Bond-length mapping without two-dimensional scanning by means of photoemission electron microscopy-extended X-ray absorption fine structure measurement Peer-reviewed

Masako Suzuki-Sakamaki, Kenta Amemiya

Japanese Journal of Applied Physics　59　(10)　105504-105504　2020/10/01
Publisher: {IOP} Publishing
DOI： 10.35848/1347-4065/abb716 　

ISSN： 0021-4922

eISSN： 1347-4065
Development of fluorescence-yield wavelength-dispersive x-ray absorption spectroscopy in the soft x-ray region for time-resolved experiments Peer-reviewed

Amemiya, K., Sakata, K., Suzuki-Sakamaki, M.

Review of Scientific Instruments　91　(9)　093104-1-093104-5　2020
Publisher: AIP Publishing
DOI： 10.1063/5.0021981 　

ISSN： 0034-6748

eISSN： 1089-7623
Bond-length mapping without two-dimensional scanning by means of photoemission electron microscopy-extended X-ray absorption fine structure measurement Peer-reviewed

Masako Suzuki-Sakamaki, Kenta Amemiya

Japanese Journal of Applied Physics　59　(10)　105504-1-105504-6　2020
Publisher: {IOP} Publishing
DOI： 10.35848/1347-4065/abb716 　

ISSN： 0021-4922

eISSN： 1347-4065
Development of sub-nanometer resolution depth-resolved XAFS/XMCD in the soft X-ray region towards operando measurements Peer-reviewed

Kenta Amemiya,Masako Sakamaki

AIP Conference Proceedings　(2045)　040001-1-040001-6　2019/01

DOI： 10.1063/1.5084602 　
Attempt to generate x-ray beam carrying orbital angular momentum in photon factory Peer-reviewed

Hironori Nakao,Yuichi Yamasaki,Masaichiro Mizumaki,Chihiro Tabata,Masako Sakamaki,Kenta Amemiya

AIP Conference Proceedings　(2054)　060035-1-060035-6　2019/01

DOI： 10.1063/1.5084666 　
Experimental evidence of orbital ferrimagnetism in CoMnO3(0001) epitaxial thin film Peer-reviewed

Hiroki Koizumi,Sonia Sharmin,Kenta Amemiya,Masako Suzuki-Sakamaki,Jun-ichiro Inoue,Hideto Yanagihara

Physical Review Materials　3　024404-1-024404-6　2019/01

DOI： 10.1103/PhysRevMaterials.3.024404 　
Development of high signal-to-background ratio depth-resolved soft X-ray absorption spectroscopy by fluorescence energy selection Peer-reviewed

Masako Suzuki-Sakamaki, Kenta Amemiya

Japanese Journal of Applied Physics　57　(12)　120308-120308　2018/12/01
Publisher: Japan Society of Applied Physics
DOI： 10.7567/JJAP.57.120308 　
Manipulation of magnetic properties of ferromagnetic Ni thin films grown on Cu(001) by antiferromagnetic NiO and effects of voltage application

Kenta Amemiya,Kenta Amemiya,Masako Sakamaki,Masako Sakamaki

Japanese Journal of Applied Physics　57　0902B3　2018/09

DOI： 10.7567/JJAP.57.0902B3 　

ISSN： 0021-4922

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© 2018 The Japan Society of Applied Physics. The magnetic properties of ferromagnetic Ni thin films grown on a Cu(001) single crystal are modified by the growth of a NiO overlayer, as well as by the voltage application through the NiO/Ni interface. A spin reorientation transition from in-plane to perpendicular magnetization is induced with increasing NiO thickness, and the coercive field significantly increases by further growth of the NiO overlayer. The remanent magnetization of the films is found to be modulated by the voltage application. Moreover, a small exchange-bias effect arising from the ferromagnetic-antiferromagnetic interaction at the interface is observed, and the amplitude of the effect is modified by the applied voltage.
Effect of interface NiO layer on magnetism in Fe/BaTiO<inf>3</inf>thin film

Masako Sakamaki,Masako Sakamaki,Kenta Amemiya,Kenta Amemiya

Japanese Journal of Applied Physics　57　0902B9　2018/09

DOI： 10.7567/JJAP.57.0902B9 　

ISSN： 0021-4922

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© 2018 The Japan Society of Applied Physics. The insertion effect of an interface NiO layer on magnetism in Fe/BaTiO3is investigated by X-ray absorption spectroscopy (XAS). From X-ray magnetic circular dichroism (XMCD) analysis, the enhancement of remanent magnetization in Fe is observed with increasing NiO thickness. We also find that the NiO layer is partially composed of metallic Ni, and its thickness is estimated to be >0.4 nm from the NiO-thickness dependence of the Ni XAS intensity by assuming that Ni is localized at the interface between Fe and NiO. Moreover, extended X-ray absorption fine structure data shows that the Ni-O distance of the interface NiO layer is shorter than that of bulk NiO, which leads to the pseudomorphic growth of NiO on BaTiO3. We thus suppose that the improved Fe growth promoted by the interface NiO layer enhances the magnetic moment in Fe.
Origin of focused laser irradiation-induced enhancement of perpendicular magnetic anisotropy in Pt/Co/Pt thin films investigated by spatially resolved x-ray absorption spectroscopy Peer-reviewed

Amemiya, K., Sakamaki, M., Kisielewski, J., Kurant, Z., Sveklo, I., Tekielak, M., Wawro, A., Maziewski, A.

Journal of Applied Physics　124　(12)　123903　2018/09

DOI： 10.1063/1.5049182 　

ISSN： 0021-8979
Observation of an electric field-induced interface redox reaction and magnetic modification in GdOx/Co thin film by means of depth-resolved X-ray absorption spectroscopy

Masako Sakamaki,Masako Sakamaki,Kenta Amemiya,Kenta Amemiya

Physical Chemistry Chemical Physics　20　20004-20009　2018/07

DOI： 10.1039/c8cp02972e 　

ISSN： 1463-9076
Irradiation effect on magnetic properties of FeRh thin films with energetic C60b cluster ion beam Peer-reviewed

R. Soma,Y. Saitoh,M. Sakamaki,K. Amemiya,A. Iwase,T. Matsui

AIP Advances　8　056433-1-056433-4　2018/01

DOI： 10.1063/1.5007704 　
Effect of electric field on magnetism of ni thin films via antiferromagnetic NiO Peer-reviewed

Amemiya K,Sakamaki M

e-Journal of Surface Science and Nanotechnology　16　186-189　2018
Effects of cobalt substitution in L1(0) -(Fe,Co)Pt thin films Peer-reviewed

Shoya Sakamoto,Kumar Srinivasan,Rui Zhang,Oleg Krupin,Keisuke Ikeda,Goro Shibata,Yosuke Nonaka,Zhendong Chi,Masako Sakamaki,Kenta Amemiya,Atsushi Fujimori,Antony Ajan

PHYSICAL REVIEW B　96　(14)　144437-1-144437-5　2017/10
Publisher: AMER PHYSICAL SOC
DOI： 10.1103/PhysRevB.96.144437 　

ISSN： 2469-9950

eISSN： 2469-9969

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We have studied the effect of cobalt substitution in L1(0)-Fe1-xCox Pt films by means of x-ray magnetic circular dichroism (XMCD) and first-principles calculations. The magnetic moments of Fe (similar to 2.5 mu(B)) and Co (similar to 1.5 mu(B)) deduced using XMCD were almost unchanged upon Co doping, and the net magnetization decreases with increasing Co content. Calculation also showed that the 3d electrons that have been added by Co substitution occupy only spin-down bands.
Magnetic anisotropy of L1(0)-ordered FePt thin films studied by Fe and Pt L-2;3-edges x-ray magnetic circular dichroism Peer-reviewed

K. Ikeda,T. Seki,G. Shibata,T. Kadono,K. Ishigami,Y. Takahashi,M. Horio,S. Sakamoto,Y. Nonaka,M. Sakamaki,K. Amemiya,N. Kawamura,M. Suzuki,K. Takanashi,A. Fujimori

APPLIED PHYSICS LETTERS　111　(14)　142402-1-142402-5　2017/10
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.4993077 　

ISSN： 0003-6951

eISSN： 1077-3118

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The strong perpendicular magnetic anisotropy of L1(0)-ordered FePt has been the subject of extensive studies for a long time. However, it is not known which element, Fe or Pt, mainly contributes to the magnetic anisotropy energy. We have investigated the anisotropy of the orbital magnetic moments of Fe 3d and Pt 5d electrons in L1(0)-ordered FePt thin films by Fe and Pt L-2; 3-edge x-ray magnetic circular dichroism (XMCD) measurements for samples with various degrees of long-range chemical order S. Fe L-2;3-edge XMCD showed that the orbital magnetic moment was larger when the magnetic field was applied perpendicular to the film than parallel to it and that the anisotropy of the orbital magnetic moment increased with S. Pt L-2;3-edge XMCD also showed that the orbital magnetic moment was smaller when the magnetic field was applied perpendicular to the film than parallel to it, opposite to the Fe L-2;3-edge XMCD results although the anisotropy of the orbital magnetic moment increases with S like the Fe edge. These results are qualitatively consistent with the first-principles calculation by Solovyev et al. [Phys. Rev. B 52, 13419 (1995)], which also predicts the dominant contributions of Pt 5d to the magnetic anisotropy energy rather than Fe 3d due to the strong spin-orbit coupling and the small spin splitting of the Pt 5d bands in L1(0)-ordered FePt. Published by AIP Publishing.
Nanometer-resolution depth-resolved measurement of florescence-yield soft x-ray absorption spectroscopy for FeCo thin film Peer-reviewed

M. Sakamaki,K. Amemiya

REVIEW OF SCIENTIFIC INSTRUMENTS　88　(8)　083901-1-083901-4　2017/08
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.4986146 　

ISSN： 0034-6748

eISSN： 1089-7623

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We develop a fluorescence-yield depth-resolved soft x-ray absorption spectroscopy (XAS) technique, which is based on the principle that the probing depth is changed by the emission angle of the fluorescence soft x rays. Compared with the electron-yield depth-resolved XAS technique, which has been established in this decade, we can observe wider range in-depth XAS distribution up to several tens of nm. Applying this technique to a 30 ML (similar to 4.3 nm) FeCo thin film, we observe Fe L-edge XAS spectra at the probing depth of 0.3-6 nm and find that the film has 22 ML (similar to 3.1 nm) surface oxide layer while its inner layer shows metallic state. We thus successfully obtain nanometer-resolution depth-resolved XAS spectra and further expect that operando measurement under the electric and/or magnetic fields is possible. Published by AIP Publishing.
Demonstration of One-shot Spatially-resolved X-ray Absorption Spectroscopy Using Wavelength-dispersed Soft X-rays Peer-reviewed

Kenta Amemiya,Masako Sakamaki

CHEMISTRY LETTERS　46　(1)　71-73　2017/01
Publisher: CHEMICAL SOC JAPAN
DOI： 10.1246/cl.160886 　

ISSN： 0366-7022

eISSN： 1348-0715

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A one-shot recording technique for spatially-resolved X-ray absorption spectroscopy has been developed by combining wavelength-dispersed soft X-rays with a photoelectron emission microscope. The wavelength-dispersed soft X-rays, whose wavelength depends on the position, illuminate the sample, and a two-dimensional image of emitted electrons is obtained. Therefore, one can obtain spatial and spectroscopic information simultaneously, without scanning the monochromator. The technique opens the route to quantitative investigation for inhomogeneous and irreversible surface chemical reactions.
Formation of Co nanodisc with enhanced perpendicular magnetic anisotropy driven by Ga+ ion irradiation on Pt/Co/Pt films Peer-reviewed

M. Sakamaki,K. Amemiya,I. Sveklo,P. Mazalski,M. O. Liedke,J. Fassbender,Z. Kurant,A. Wawro,A. Maziewski

PHYSICAL REVIEW B　94　(17)　174422-1-174422-8　2016/11
Publisher: AMER PHYSICAL SOC
DOI： 10.1103/PhysRevB.94.174422 　

ISSN： 2469-9950

eISSN： 2469-9969

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The origin of magnetic phase transition from in-plane to perpendicular magnetic anisotropy (PMA) of Pt/Co/Pt thin film by Ga+ ion irradiation at fluences of 1-5 x 10(15) ions/cm(2) is investigated by means of x-ray magnetic circular dichroism (XMCD) and extended x-ray absorption fine structure (EXAFS) analyses. We find that Pt and Co atoms are mixed with each other and that Co is oxidized near the surface due to removal of the Pt overlayer. Furthermore, polarization-dependent EXAFS analysis shows that Co is firstly dispersed as separated single-atom-thick sheets in a Pt matrix at 1 x 10(15) ions/cm(2), then the Co sheets are divided into a few angstrom clusters at 5 x 10(15) ions/cm(2), which are regarded as nanodiscs parallel to the film plane. This process is accompanied by the appearance of an out-of-plane magnetization component and a remanence peak is observed. Because we do not observe an enhancement in anisotropy of Co orbital moment which leads to change in magnetic anisotropy through the transition at about 5 x 10(15) ions/cm(2), it might be possible that such nanodisc formation induces increase of magnetic anisotropy via a shape effect. By comparing with the phase transition observed at lower fluence [Phys. Rev. B 86, 024418 (2012)], we find that the mechanism of two transitions is different, i.e., the transition at lower fluence is caused by anisotropy of orbital moment due to structural strain, while the present transition is possibly by shape effect due to nanodisc formation.
19pBE-2 Magnetic exchange coupling through the interface oxide layers in Fe/BaTiO_3 and its influence on the electric field effect

Sakamaki M., Amemiya K.

Meeting Abstracts of the Physical Society of Japan　71　2500-2500　2016
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.71.1.0_2500 　

ISSN： 2189-079X
19pBE-3 Electric field effect on Ni/Cu(001) thin films via antiferromagnetic NiO

Amemiya K., Sakamaki M.

Meeting Abstracts of the Physical Society of Japan　71　2501-2501　2016
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.71.1.0_2501 　

ISSN： 2189-079X
Depth-resolved X-ray magnetic circular dichroism measurement by a multi-anode microchannel plate detector combined with polarization switching Peer-reviewed

K. Amemiya,M. Sakamaki,S. Kishimoto,T. Kosuge,K. Nigorikawa,M. Tanaka,T. Uchida,M. Saito,M. Ikeno,K. Nakayoshi

16TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS16)　712　012033-1-012033-4　2016
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/712/1/012033 　

ISSN： 1742-6588

eISSN： 1742-6596

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A depth-resolved X-ray magnetic circular dichroism (XMCD) technique has been developed in the soft X-ray region by combining a multi-anode microchannel plate detector with polarization switching between right and left circular polarizations. A simultaneous measurement for 30-channel anodes has been achieved with a continuous data acquisition rate of 1 kHz, which is fast enough for 10 Hz polarization switching. This enables us to realize the layer-resolved XMCD analysis with a high signal-to-noise ratio.
Mechanism of perpendicular magnetic anisotropy in Pt/Co/Pt thin films by laser irradiation

Amemiya Kenta, Sakamaki Masako

Meeting Abstracts of the Physical Society of Japan　71　945-945　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_945 　
Oxgen transfer at Fe/NiO interface and change in the magnetic moment of Fe

Sakamaki Masako, Amemiya Kenta

Meeting Abstracts of the Physical Society of Japan　71　944-944　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_944 　
In-situ XMCD evaluation of ferromagnetic state at FeRh thin film surface induced by 1 keV Ar ion beam irradiation and annealing Peer-reviewed

T. Matsui,K. Aikoh,M. Sakamaki,K. Amemiya,A. Iwase

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS　365　187-190　2015/12
Publisher: ELSEVIER SCIENCE BV
DOI： 10.1016/j.nimb.2015.07.060 　

ISSN： 0168-583X

eISSN： 1872-9584

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Surface ferromagnetic state of FeRh thin films irradiated with 1 keV Ar ion-beam has been investigated by using soft X-ray Magnetic Circular Dichroism (XMCD). It was revealed that the Fe atoms of the samples were strongly spin-polarized after Ar ion-beam irradiation. Due to its small penetration depth, 1 key Ar ion-beam irradiation can modify the magnetic state at subsurface of the samples. In accordance with the XMCD sum rule analysis, the main component of the irradiation induced ferromagnetism at the FeRh film surface was to be effective spin magnetic moment, and not to be orbital moment. We also confirmed that the surface ferromagnetic state could be produced by thermal annealing of the excessively ion irradiated paramagnetic subsurface of the FeRh thin films. This novel magnetic modification technique by using ion irradiation and subsequent annealing can be a potential tool to control the surface magnetic state of FeRh thin films. (C) 2015 Elsevier B.V. All rights reserved.
Magnetic modification at sub-surface of FeRh bulk by energetic ion beam irradiation Peer-reviewed

T. Koide,H. Uno,H. Sakane,M. Sakamaki,K. Amemiya,A. Iwase,T. Matsui

JOURNAL OF APPLIED PHYSICS　117　(17)　17E503-1-17E503-3　2015/05
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.4914123 　

ISSN： 0021-8979

eISSN： 1089-7550

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Ferromagnetic layered structure has been made at sub-surface of the antiferromagnetic FeRh bulk samples by high energy He ion beam irradiation. In accordance with the Transport of Ions in Matter simulation, such ion beam can effectively deposit the elastic collision energy in several mu m regions in the depth from the surface. Measurement with a superconducting quantum interference device reveals the irradiated samples to be ferromagnetic. Assuming that only the part the energy deposited can be modified to be ferromagnetic, the corresponding irradiation induced magnetization is consistent with the data that we previously reported. On the other hand, the X-ray magnetic circular dichroism (XMCD) spectra for the irradiated samples are totally unchanged as those for the unirradiated samples. Since XMCD signal in total emission yield method is considered to be surface sensitive with a typical probing depth of several nm, the surface magnetic state is maintained to be antiferromagnetic. By utilizing these phenomena, three-dimensional magnetic patterning of FeRh can be realized, which may potentially be used for future magnetic exchange device application such as nano-scale sensors and memories. (C) 2015 AIP Publishing LLC.
Voltage-Induced Changes in Magnetism of FeCo/BaTiO3 Thin Films Studied by X-Ray Absorption Spectroscopy Peer-reviewed

AMEMIYA Kenta,SAKAMAKI Masako

e-Journal Surf Sci Nanotechnol (Web)　13　465-468 (J-STAGE)　2015

DOI： 10.1380/ejssnt.2015.465 　

ISSN： 1348-0391
Observation of Fe/BaTiO3 Interface State by X-Ray Absorption Spectroscopy Peer-reviewed

SAKAMAKI Masako,AMEMIYA Kenta

e-Journal Surf Sci Nanotechnol (Web)　13　139-142 (J-STAGE)　2015

DOI： 10.1380/ejssnt.2015.139 　

ISSN： 1348-0391
Magnetic Field Dependence of the Canted Spin Moment around the Interface between Ferromagnetic Ni and Antiferromagnetic FeMn Revealed by the Polarized Neutron Reflectivity Peer-reviewed

K.Amemiya,M.Sakamaki,M.Mizusawa,M.Takeda

JPS Conf. Proc.　8　034004-1-034004-6　2015

DOI： 10.7566/JPSCP.8.034004 　
17pCB-5 Observation of magnetism and structure at surface and interface by means of depth-resolved X-ray absorption spectroscopy

Amemiya K., Sakamaki M.

Meeting Abstracts of the Physical Society of Japan　70　2283-2283　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.2.0_2283 　

ISSN： 2189-079X
19aCG-5 Ni and NiO thickness dependence of magnetism of NiO/Ni/Cu(001) thin films and its electric field effect

Amemiya K., Sakamaki M.

Meeting Abstracts of the Physical Society of Japan　70　970-970　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.2.0_970 　

ISSN： 2189-079X
19aCG-4 Control of the interface state and the electric-field effect of Fe/BaTiO3

Sakamaki M., Amemiya K.

Meeting Abstracts of the Physical Society of Japan　70　969-969　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.2.0_969 　

ISSN： 2189-079X
21pAB-6 Influence of interface oxide layer on the magneto-electric effect of BaTiO_3/Fe

Sakamaki M., Amemiya K.

Meeting Abstracts of the Physical Society of Japan　70　2521-2521　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.1.0_2521 　

ISSN： 2189-079X
21pAB-7 Magnetism and electric field effect of NiO/Ni thin films grown on Cu(001)

Amemiya K., Sakamaki M.

Meeting Abstracts of the Physical Society of Japan　70　2522-2522　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.1.0_2522 　

ISSN： 2189-079X
Structures of Fe Magnetic Ultrathin Films on Cu(001) Before and After CO Adsorption Revealed by EXAFS Peer-reviewed

Hitoshi Abe,Masako Sakamaki,Kenta Amemiya

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　83　(8)　084603.1-084603.4　2014/08
Publisher: PHYSICAL SOC JAPAN
DOI： 10.7566/JPSJ.83.084603 　

ISSN： 0031-9015

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The structures of the Fe(2 and 4 ML)/Cu(001) films before and after CO adsorption are revealed by EXAFS. The Fe(2 ML)/Cu(001) film shows an fcc structure before and after CO adsorption. The bare Fe(4 ML)/Cu(001) film also have an fcc structure. However, the CO adsorbed Fe(4 ML)/Cu(001) film changes its structure to the mixture of fcc and strained bcc structures. The strained bcc structure is closely examined, and the shear angle of 10 degrees is most plausible. The relationship between the structure and magnetism has been discussed. The magnetically dead layers have been reported for the CO/Fe(4 ML)/Cu(001) film, and it is concluded that the dead layers correspond to this strained bcc structure.
Change in magnetic and structural properties of FeRh thin films by gold cluster ion beam irradiation with the energy of 1.67 MeV/atom Peer-reviewed

T. Koide,Y. Saitoh,M. Sakamaki,K. Amemiya,A. Iwase,T. Matsui

JOURNAL OF APPLIED PHYSICS　115　(17)　17B722-17B722-3　2014/05
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.4864745 　

ISSN： 0021-8979

eISSN： 1089-7550

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The effect of energetic cluster ion beam irradiation on magnetic and structural properties of FeRh thin films have been investigated. The cluster ions used in the present studies consist of a few gold atoms with the energy of 1.67MeV/gold atom. Saturation magnetization of the sample irradiated with Au3 cluster ion beam (280 emu/cc) is larger than that for the irradiated sample with Au1 ion beam (240 emu/cc) for the same irradiation ion fluence. These results can also be confirmed by the X-ray magnetic circular dichroism (XMCD) measurement; the XMCD signal for Au3 cluster ion irradiation is larger than that for Au1 ion irradiation. Since the ion beam irradiation induced magnetization of FeRh is significantly correlated with the amount of the lattice defects in the samples, cluster ion beam irradiation can be considered to effectively introduce the lattice defects in B2-type FeRh rather than the single ion beam. Consequently, cluster ion irradiation is better than single ion irradiation for the viewpoint of saturation magnetization, even if the same irradiation energy is deposited in the samples. (C) 2014 AIP Publishing LLC.
Enhancement of perpendicular magnetic anisotropy by compressive strain in alternately layered FeNi thin films

M. Sakamaki,K. Amemiya

JOURNAL OF PHYSICS-CONDENSED MATTER　26　(16)　2014/04
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/0953-8984/26/16/166002 　

ISSN： 0953-8984

eISSN： 1361-648X

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The effect of the lattice strain on magnetic anisotropy of alternately layered FeNi ultrathin films grown on a substrate, Cu(t(Cu) = 0-70 ML)/Ni48Cu52(124 ML)/Cu(001) single crystal, is systematically studied by means of in situ x-ray magnetic circular dichroism (XMCD) and reflection high-energy electron diffraction (RHEED) analyses. To investigate the magnetic anisotropy of the FeNi layer itself, a non-magnetic substrate is adopted. From the RHEED analysis, the in-plane lattice constant, a(in), of the substrate is found to shrink by 0.8% and 0.5% at tCu = 0 and 10 ML as compared to that of bulk Cu, respectively. Fe L-edge XMCD analysis is performed for n ML FeNi films grown on various ain, and perpendicular magnetic anisotropy (PMA) is observed at n = 3 and 5, whereas the film with n = 7 shows in-plane magnetic anisotropy. Moreover, it is found that PMA is enhanced with decreasing ain, in the case where a Cu spacer layer is inserted. We suppose that magnetic anisotropy in the FeNi films is mainly carried by Fe, and the delocalization of the in-plane orbitals near the Fermi level increases the perpendicular orbital magnetic moment, which leads to the enhancement of PMA.
Twisted magnetic structure in ferromagnetic ultrathin Ni films induced by magnetic anisotropy interaction with antiferromagnetic FeMn Peer-reviewed

Kenta Amemiya,Masako Sakamaki,Mari Mizusawa,Masayasu Takeda

PHYSICAL REVIEW B　89　(5)　054404.1-054404.6　2014/02
Publisher: AMER PHYSICAL SOC
DOI： 10.1103/PhysRevB.89.054404 　

ISSN： 1098-0121

eISSN： 1550-235X

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A twisted magnetic structure in Ni ultrathin films attached to antiferromagnetic FeMn is revealed by a combination of the depth-resolved x-ray magnetic circular dichroism (XMCD) and the polarized neutron reflectivity (PNR) techniques. The depth-resolved XMCD at remanent magnetization shows that the perpendicular magnetization component in the Ni film decreases around the interface to FeMn when the film exhibits perpendicular magnetization, whereas the in-plane component is kept constant through the whole film in the case of in-plane magnetization. Moreover, the PNR data shows that when a weak in-plane magnetic field is applied to a film, which exhibits perpendicular magnetization at the remanent state, an in-plane magnetization component is induced in Ni around the interface to FeMn. These results are reasonably interpreted by assuming that the magnetic moment in the Ni layer is twisted from the perpendicular to the in-plane directions towards the interface to FeMn. Such a magnetic structure is supposed to be induced by a magnetic anisotropy interaction at the interface between ferromagnetic Ni and antiferromagnetic FeMn, which makes the Ni magnetic moment around the interface rotate towards the in-plane direction.
Ar+ ion milling-induced suppression of surface oxidation in Fe70Co30 thin films Peer-reviewed

Masako Sakamaki,Kenta Amemiya,Akira Nambu,Kazuhiro Ueda,Jun-ichiro Shimizu,Katsuro Watanabe

MATERIALS CHEMISTRY AND PHYSICS　143　(1)　281-285　2013/12
Publisher: ELSEVIER SCIENCE SA
DOI： 10.1016/j.matchemphys.2013.08.065 　

ISSN： 0254-0584

eISSN： 1879-3312

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We show from the depth-resolved X-ray absorption analysis that the degree of surface oxidation of Fe70Co30 thin films is reduced by Ar+ ion milling even if the film is exposed to air after ion milling. The milled film has thinner surface oxide layer and smaller ratio of Fe oxide component in the surface layer than those of the as-deposited film. It is also indicated that selective oxidation of Fe proceeds accompanied by the movement of Fe atoms toward the surface. The suppression of oxidation is explained by the obstruction of Fe movement toward the surface by the milling-induced disorder. (C) 2013 Elsevier B.V. All rights reserved.
Temperature dependence of remanent magnetization of thin films at the interface to a nonmagnetic material: Cu/Ni/Cu(100) Peer-reviewed

AMEMIYA Kenta,SAKAMAKI Masako

Phys Rev B Condens Matter Mater Phys　88　(1)　014401.1-014401.5　2013/07

DOI： 10.1103/PhysRevB.88.014401 　

ISSN： 1098-0121
Ga⁺ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt thin film studied by X-ray magnetic circular dichroism

K. Amemiya,M. Sakamaki,P. Mazalski,I. Sveklo,Z. Kurant,A. Maziewski,M. O. Liedke,J. Fassbender,A. Wawro,L. T. Baczewski

EPJ Web of Conferences　40　2013/01/28

DOI： 10.1051/epjconf/20134008002 　

ISSN： 2101-6275

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Ga+ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+fluences of ∼1-2×1014ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+fluences of ∼5×1015ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+fluences. © 2013 Owned by the authors, published by EDP Sciences.
Effect of structural strain on magnetic anisotropy energy of each element in alternately layered FeNi thin films Peer-reviewed

SAKAMAKI Masako,AMEMIYA Kenta

Phys Rev B Condens Matter Mater Phys　87　(1)　014428.1-014428.5　2013/01

DOI： 10.1103/PhysRevB.87.014428 　

ISSN： 1098-0121
Operation of a fast polarization-switching source at the Photon Factory

Kimichika Tsuchiya,Tatsuro Shioya,Tomohiro Aoto,Kentaro Harada,Takashi Obina,Masako Sakamaki,Kenta Amemiya

11TH INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (SRI 2012)　425　2013
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/425/13/132017 　

ISSN： 1742-6588

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We have been developing a fast polarization-switching source for the vacuum ultraviolet and soft X-ray region at the B15-16 straight section of the 2.5-GeV Photon Factory (PF) storage ring. The source consists of two tandem APPLE-II-type elliptically polarizing undulators (EPUs), namely, U#16-1 and U#16-2, and a fast kicker system. The target frequency of polarization switching is 10 Hz. As the first step, we installed U#16-1 and five identical bump kickers in the PF ring in March 2008. Then, we constructed U#16-2 and installed it in August 2010. The orbit switching operation at 10 Hz, for user experiments, started in January 2012. We describe the details of the operation status of two EPUs and the fast local bump system in this report.
Proximity effects and exchange bias in Co/MnF2(111) heterostructures studied by x-ray magnetic circular dichroism

S. M. Suturin,V. V. Fedorov,A. G. Banshchikov,D. A. Baranov,K. V. Koshmak,P. Torelli,J. Fujii,G. Panaccione,K. Amemiya,M. Sakamaki,T. Nakamura,M. Tabuchi,L. Pasquali,N. S. Sokolov

JOURNAL OF PHYSICS-CONDENSED MATTER　25　(4)　2013/01
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/0953-8984/25/4/046002 　

ISSN： 0953-8984

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Cobalt nano-structured ultrathin films were grown on orthorhombic MnF2 by molecular beam epitaxy on CaF2 epitaxial layers deposited on Si(111) substrates. The Co film was grown at room temperature. It was found to be polycrystalline, forming nano-islands with height approximate to diameter <= 10 nm. X-ray absorption evidences the chemical stability of the Co/MnF2 interface. Remarkably, x-ray magnetic circular dichroism (XMCD) demonstrates that the Co induces a net magnetization on the Mn ions close to the interface. The magnetic moments of these Mn ions couple antiparallel to the Co and rotate upon field reversal following the magnetization of the Co both below and high above the Neel temperature of MnF2 (T-N = 67 K). The density of coupled Mn moments is found to be temperature dependent, with an equivalent thickness of similar to 1.5 MnF2 monolayers at 20 K, decreasing to about similar to 0.5 ML as the temperature is raised to 300 K. Interestingly, the intensity of the Mn XMCD signal appears to be related to the coercivity of the Co layer. This behavior is interpreted in terms of the competition between thermal fluctuations, exchange coupling between Co and Mn at the interface and, at low temperature, the antiferromagnetic order in MnF2.
Fast polarization switching in the soft X-ray region at PF BL-16A

K. Amemiya,M. Sakamaki,T. Koide,K. Ito,K. Tsuchiya,K. Harada,T. Aoto,T. Shioya,T. Obina,S. Yamamoto,Y. Kobayashi

11TH INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (SRI 2012)　425　(15)　152015-152015　2013
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/425/15/152015 　

ISSN： 1742-6588

eISSN： 1742-6596

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Recent development in fast polarization switching at the soft X-ray beamline, BL-16A in the Photon Factory is reported. Two APPLE-II type undulators installed in a tandem configuration enables us to achieve polarization switching between not only two opposite circular polarizations, but also the vertical and horizontal linear polarizations. An energy shift is observed during polarization switching due to a vertical modulation in the electron beam, which has been reduced by properly correcting the electron orbit.
Molecular orientation change during adsorption of NO and N2O on Ir(111) observed by real-time wavelength-dispersive x-ray absorption spectroscopy with polarization switching Peer-reviewed

Kenta Amemiya,Masako Sakamaki,Shuichi Nakamoto,Masaaki Yoshida,Kazuma Suzuki,Hiroshi Kondoh,Tsuneharu Koide,Kenji Ito,Kimichika Tsuchiya,Kentaro Harada,Hiroyuki Sasaki,Tomohiro Aoto,Tatsuro Shioya,Takashi Obina,Shigeru Yamamoto,Yukinori Kobayashi

APPLIED PHYSICS LETTERS　101　(16)　161601-161601-4-161601　2012/10
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.4759114 　

ISSN： 0003-6951

eISSN： 1077-3118

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The molecular orientation of NO and N2O during adsorption on Ir(111) is observed by combining the wavelength-dispersive x-ray absorption spectroscopy with 1 Hz switching between the vertical and horizontal linear polarizations. It is revealed that NO adsorbs keeping its molecular axis at similar to 20 degrees from surface normal. In contrast, N2O rapidly adsorbs up to 2/3 of the saturation coverage with an orientation angle of similar to 35 degrees, then turns to a slow adsorption phase with larger orientation angles, and gradually reaches its saturation with an average orientation angle of similar to 45 degrees. Such a complicated behavior is interpreted by assuming different adsorption sites. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759114]
Perpendicular magnetic anisotropy in a Pt/Co/Pt ultrathin film arising from a lattice distortion induced by ion irradiation Peer-reviewed

SAKAMAKI M,AMEMIYA K,LIEDKE M. O,FASSBENDER J,MAZALSKI P,SVEKLO I,MAZIEWSKI A

Phys Rev B Condens Matter Mater Phys　86　(2)　024418.1-024418.5　2012/07

DOI： 10.1103/PhysRevB.86.024418 　

ISSN： 1098-0121
Observation of magnetic moments at the interface region in magnetic tunnel junctions using depth-resolved x-ray magnetic circular dichroism Peer-reviewed

TSUNEGI S,SAKURABA Y,AMEMIYA K,SAKAMAKI M,OZAWA E,SAKUMA A,TAKANASHI K,ANDO Y

Phys Rev B Condens Matter Mater Phys　85　(18)　180408.1-180408.4　2012/05

DOI： 10.1103/PhysRevB.85.180408 　

ISSN： 1098-0121
XAFS and XMCD Spectra at the Surface and Interface of Ultrathin Films Observed by the Depth-Resolved XAFS/XMCD Technique Peer-reviewed

AMEMIYA Kenta,SAKAMAKI Masako

e-Journal Surf Sci Nanotechnol (Web)　10　521-524 (J-STAGE)　2012

DOI： 10.1380/ejssnt.2012.521 　

ISSN： 1348-0391
In Situ Observation of Magnetic Anisotropy Energy of Alternately Layered FeNi Thin Films Peer-reviewed

SAKAMAKI Masako,AMEMIYA Kenta

e-Journal Surf Sci Nanotechnol (Web)　10　97-99 (J-STAGE)　2012

DOI： 10.1380/ejssnt.2012.97 　

ISSN： 1348-0391
Anomalous electronic states of hollandite-type transition-metal oxides

Y. Ohta,T. Toriyama,M. Sakamaki,T. Konishi

26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5　400　(3)　032070-032070　2012
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/400/3/032070 　

ISSN： 1742-6588

eISSN： 1742-6596

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We make the electronic structure calculations of transition-metal oxides with the hollandite-type crystal structure A(2)M(8)O(16) using the generalized gradient approximation (GGA) in the density functional theory, where the Hubbard-type repulsive interaction is taken into account (GGA+U). We first discuss generic electronic structures of the 3d (M=Ti, V, Cr, Mn) and 4d (M=Mo, Ru, Rh) series of the materials and then consider the origins of the metal-insulator transition observed in K2Cr8O16 and quasi-one-dimensional electron conduction observed in K2Ru8O16. We also consider in particular the observed metal-insulator transition in K2V8O16.
Real-time observation of CO oxidation reaction on Ir(111) surface at 33 ms resolution by means of wavelength-dispersive near-edge x-ray absorption fine structure spectroscopy Peer-reviewed

Kenta Amemiya,Yuka Kousa,Shuichi Nakamoto,Taiga Harada,Shogo Kozai,Masaaki Yoshida,Hitoshi Abe,Ryohei Sumii,Masako Sakamaki,Hiroshi Kondoh

APPLIED PHYSICS LETTERS　99　(7)　074104　2011/08
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.3624587 　

ISSN： 0003-6951

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The CO oxidation reaction on Ir(111) is observed by the near-edge x-ray absorption fine structure (NEXAFS) spectroscopy in the soft x-ray region. A continuous data acquisition at 33 ms real-time resolution is realized for a single event of the reaction without the repetition, by adopting the wavelength-dispersive NEXAFS technique. The time evolution of the coverages for atomic O and molecular CO is quantitatively estimated during the reaction. The obtained activation energy is significantly larger than that on Pt(111). (C) 2011 American Institute of Physics. [doi:10.1063/1.3624587]
Element Specific Magnetic Anisotropy Energy of Alternately Layered FeNi Thin Films Peer-reviewed

Masako Sakamaki,Kenta Amemiya

APPLIED PHYSICS EXPRESS　4　(7)　073002.1-073002.3　2011/07
Publisher: JAPAN SOC APPLIED PHYSICS
DOI： 10.1143/APEX.4.073002 　

ISSN： 1882-0778

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The element specific magnetic anisotropy energy (MAE) of alternately layered FeNi thin films grown on Ni (4-20 MLs)/Cu(001) is investigated by means of the X-ray magnetic circular dichroism (XMCD) and magneto-optic Kerr effect (MOKE). Although surface Fe is known to show strong perpendicular magnetic anisotropy, the Ni-sandwiched Fe layer has a tiny MAE of 10 +/- 40 mu eV. On the other hand, the Fe-sandwiched Ni layer has a Positive MAE of 60 +/- 30 mu eV. The total MAE simulated from the XMCD analysis shows good agreement with the MOKE result. We demonstrate that in-situ analysis of the element specific MAE gives a possible strategy for manipulating the magnetic anisotropy of multilayers. (C) 2011 The Japan Society of Applied Physics
Observation of disorder-driven carrier localization by Auger resonant Raman scattering in n-type doped ZnO Peer-reviewed

SAKAMAKI M,KAWAI N,MIKI T,KANEKO T,KONISHI T,FUJIKAWA T,AMEMIYA K,KITAJIMA Y,KATO Y,MURO T,YAMAUCHI H,SAKAI M

Phys Rev B Condens Matter Mater Phys　83　(15)　155210.1-155210.7　2011/04

DOI： 10.1103/PhysRevB.83.155210 　

ISSN： 1098-0121
Sub-nm resolution depth profiling of the magnetic structure of thin films by the depth-resolved x-ray magnetic circular dichroism technique

K. Amemiya,M. Sakamaki

JOURNAL OF PHYSICS D-APPLIED PHYSICS　44　(6)　2011/02
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/0022-3727/44/6/064018 　

ISSN： 0022-3727

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The principle and applications of the depth-resolved x-ray magnetic circular dichroism (XMCD) technique are demonstrated, by which depth profiling of the magnetic structure of thin films is achieved with sub-nm resolution. The formation of a NiO-like layer at the surface of a Ni/Cu(1 0 0) thin film is revealed by this technique. Moreover, a small uncompensated magnetic moment in the surface layer is suggested, which shows an antiparallel coupling to that in the inner Ni layers. Development of a three-dimensional XMCD technique is also demonstrated, in which an x-ray microbeam is combined with the depth-resolved XMCD. A preliminary study on the magnetic anisotropy of Fe/Ni/Cu(1 0 0) is shown using this new technique.
Effect of surface roughness on magnetism of ultrathin Co films

M. Sakamaki,K. Amemiya

Journal of Physics: Conference Series　266　2011/01/01

DOI： 10.1088/1742-6596/266/1/012020 　

ISSN： 1742-6588

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Interface roughness effect on magnetic anisotropy of Co/Au are studied by using a Au substrate with "sharp" and "rough" surfaces by means of conventional and depth-resolved XMCD techniques. From the Co L-edge XMCD and sum rule analysis, the critical Co thickness of SRT from in-plane to perpendicular magnetization are found to be shifted from ∼0.8 to ∼1.1 nm by Au capping. We also found the sample with "rough" interface favors in-plane magnetization more than the sample with "sharp" interface. Compared to "sharp" sample, "rough" sample has smaller ml/msvalues, and no significant probing-depth dependence is observed. These differences in the magnetic state at the interface between "sharp" and "rough" might be caused by structural changes. Moreover, ml/msis lager for "sharp" sample especially at the interface. This can be interpreted as a large perpendicular anisotropy at the "sharp" interface, i.e. large Ks, while the magnetic anisotropy of the "rough" sample is determined by Kvmore than by Ks. © Published under licence by IOP Publishing Ltd.
NiO-like single layer formed on a Ni/Cu(001) thin film revealed by the depth-resolved x-ray absorption spectroscopy Peer-reviewed

Kenta Amemiya,Masako Sakamaki

APPLIED PHYSICS LETTERS　98　(1)　012501　2011/01
Publisher: AMER INST PHYSICS
DOI： 10.1063/1.3531668 　

ISSN： 0003-6951

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The formation of a 1-ML-thick NiO-like layer on a 5.5 ML Ni ultrathin film by Ni deposition on oxygen precovered Cu(001) is revealed by the depth-resolved x-ray absorption spectroscopy, and its magnetic properties are investigated. The surface layer exhibits a NiO-like x-ray absorption spectrum, while the underlying layers show a typical spectrum for a metallic Ni film. An uncompensated spin moment is observed in the NiO-like layer, which is antiparallel to the spin moment in the underlying Ni layers. These results demonstrate a potential to fabricate a sharp interface between ferromagnetic and antiferromagnetic materials. (C) 2011 American Institute of Physics. [doi:10.1063/1.3531668]
Erratum: K2Cr8O16 predicted as a half-metallic ferromagnet: Scenario for a metal-insulator transition (Physical Review B - Condensed Matter and Materials Physics (2009) 80 (024416))

M. Sakamaki,T. Konishi,Y. Ohta

Physical Review B - Condensed Matter and Materials Physics　82　2010/09/03

DOI： 10.1103/PhysRevB.82.099903 　

ISSN： 1098-0121
Observation of intermolecular N-I interaction during the growth of a 4-cyano-4 '-iodobiphenyl molecular crystal on GeS(001) Peer-reviewed

Ryouhei Sumii,Masako Sakamaki,Yoshihiro Matsumoto,Kenta Amemiya,Kaname Kanai,Kazuhiko Seki

SURFACE SCIENCE　604　(13-14)　1100-1104　2010/07
Publisher: ELSEVIER SCIENCE BV
DOI： 10.1016/j.susc.2010.03.020 　

ISSN： 0039-6028

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The electronic and atomic structures of 4-cyano-4 '-iodobiphenyl (CIB) during the growth of a molecular crystal on a GeS(001) substrate were studied by ultraviolet photoemission spectroscopy (UPS), atomic force microscopy (AFM), and extended X-ray absorption fine structure (EXAFS) spectroscopy. AFM images suggest that the CIB molecule grows as a microcrystal at a nominal thickness of 80 angstrom. The microcrystal grows with the crystal plane parallel to the surface and isotropic crystal axis orientation. EXAFS analysis suggests that a CIB crystal forms by strong N center dot center dot center dot I interaction, called halogen bonding. The formation of the intermolecular N center dot center dot center dot I bond was demonstrated by EXAFS analyses in which the N-I distance was determined to be 3.29 angstrom. An upward shift of the highest occupied molecular orbital level was observed by UPS and can be attributed to the aggregation of CIB molecules caused by halogen bonding. (C) 2010 Elsevier B.V. All rights reserved.
Magnetic and Film Structures of NO, CO Adsorbed Fe/Cu(001)

H. Abe,K. Amemiya,M. Sakamaki,Y. Kousa,S. Kouzai,H. Kondoh

Hyomen Kagaku (Journal of The Surface Science Society of Japan)　31　(7)　337-342　2010

DOI： 10.1380/jsssj.31.337 　

ISSN： 1881-4743 0388-5321
A new half-metallic ferromagnet K2Cr8O16 predicted by an ab-initio electronic structure calculation

M. Sakamaki,T. Konishi,T. Shirakawa,Y. Ohta

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009)　200　2010
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/200/1/012172 　

ISSN： 1742-6588

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The first-principles electronic structure calculation is carried out to predict that a chromium oxide K2Cr8O16 with the hollandite-type crystal structure should be a new half-metallic ferromagnet. We compare our results with recent experimental data which indicate the ferromagnetic-metal to ferromagnetic-insulator transition at T similar to 90 K, as well as the paramagnetic-metal to ferromagnetic-metal transition at T similar to 180 K. Based on the calculated electronic structures, we argue that the double-exchange mechanism is responsible for the observed saturated ferromagnetism and the formation of the incommensurate, long-wavelength density wave of spinless fermions caused by the Fermi-surface nesting may be the origin of the opening of the charge gap.
K2Cr8O16 predicted as a half-metallic ferromagnet: Scenario for a metal-insulator transition Peer-reviewed

SAKAMAKI M,KONISHI T,OHTA Y

Phys Rev B Condens Matter Mater Phys　80　(2)　024416.1-024416.6　2009/07
Publisher: American Physical Society (APS)
DOI： 10.1103/PhysRevB.80.024416 　

ISSN： 1098-0121

eISSN： 1550-235X
Depth-Resolved XMCD Study of Ultrathin Mo/Co/Au Films

M. Sakamaki,H. Abe,R. Sumii,K. Amemiya,T. Konishi,T. Fujikawa,L. T. Baczewski,A. Wawro,A. Petroutchik,Z. Kurant,A. Maziewski

ACTA PHYSICA POLONICA A　115　(1)　309-311　2009/01
Publisher: POLISH ACAD SCIENCES INST PHYSICS
ISSN： 0587-4246

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The effect of Mo overlayer on the magnetism of ultrathin Co films grown on Au(111) was studied. The structure and magnetism at the Mo/Co interface were studied by means of depth-resolved X-ray magnetic circular dichroism. The magnetic moment of Co near the Mo/Co interface was reduced in comparison to the inner part of the film for the samples which have in-plane anisotropy. This effect is more prominent in the case of Mo overlayer with higher roughness, and can be attributed to Co-Mo intermixing at the interface.
Depth profiling of magnetic and atomic structures of ultrathin films by depth-resolved XMCD and XAFS techniques with a sub-nm depth resolution

K. Amemiya,J. Miyawaki,H. Abe,E. O. Sako,M. Sakamaki

14TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS14), PROCEEDINGS　190　2009
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/190/1/012108 　

ISSN： 1742-6588

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Recent progresses in the depth-resolved X-ray magnetic circular dichroism (XMCD) and X-ray absorption fine structure (XAFS) techniques are presented. The depth-resolved atomic and magnetic structures of Co films grown on Ru(0001) was investigated by using the depth-resolved XMCD and extended X-ray absorption fine structure EXAFS. The threedimensional magnetic structure of a micro-patterned Fe/Ni/Cu(100) film was studied by combining the depth-resolved XMCD with the X-ray microbeam. The technique was also applied to Co thin films covered with a relatively thick Mo overlayer, in order to demonstrate the possibility to investigate ex-situ samples with a protection layer.
Correlation of magnetism and structure for ultra thin Au/Co/Au films: evidence for magnetoelastic effects

M. Sakamaki,T. Konishi,T. Fujikawa,A. Persson,C. Andersson,O. Karis,D. Arvanitis,H. Rossner,E. Holub-Krappe

14TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS14), PROCEEDINGS　190　2009
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/190/1/012113 　

ISSN： 1742-6588

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The spin-reorientation transition of thin Au/Co/Au films, grown in-situ on W( 110), is studied in XMCD and EXAFS experiments. At 300 K, for in-situ grown Co on a Au(111) film, the dominant easy magnetization direction was found to be in the surface plane, for the uncapped Co/Au bilayers. This is a novel observation, in terms of easy magnetization direction for low thickness Co on Au. After capping with Au, a sizeable out-of-plane magnetization is observed below a thickness of four atomic Co layers. When the spin-reorientation transition occurs because of Au capping, a 5 angstrom thin Co layer undergoes structural changes of lattice parameters Delta a/a = -1.2 % and Delta c/c = + 6.6 %. The observation of structural changes which accompany the spin reorientation transition, contradicts previous work on Co/Au( 111), and allows to quantify the magnetoelastic energy contribution, connected with the presence of the Co/Au interface.
Surface antiferromagnetic coupling of Fe/Cu(001) induced by NO adsorpion studied by means of depth-resolved XMCD method

Hitoshi Abe,Masako Sakamaki,Kenta Amemiya

14TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS14), PROCEEDINGS　190　2009
Publisher: IOP PUBLISHING LTD
DOI： 10.1088/1742-6596/190/1/012109 　

ISSN： 1742-6588

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Effects of NO adsorption on the magnetism of Fe(2 and 4 ML)/Cu(001) films have been studied. XMCD spectra have been measured for the films before and after NO adsorption. The bare 4 ML Fe film is magnetized perpendicularly, and m(s)(eff) is 2.5 mu B. However, the NO adsorbed 4 ML Fe film exhibits in- plane magnetization and shows m(s)(eff) of 1.2 mu B, which is about a half of m(s)(eff) of the bare film. The apparent fifty percent reduction of ms eff can be attributed to an idea that m(s)(eff) of 1 ML aligns in the opposite direction to that of the other 3 MLs'. This antiferromagnetic coupling between the topmost layer and the other layers is suggested by the careful analyses of the depth resolved XMCD spectra.
CO adsorption effects on the magnetism and surface structure of Fe/Cu(001)

Hitoshi Abe,Kenta Amemiya,Kenta Amemiya,Jun Miyawaki,Erika O. Sako,Masako Sakamaki,Daiju Matsumura,Takumi Ohtsuki,Enju Sakai,Toshiaki Ohta

e-Journal of Surface Science and Nanotechnology　6　233-236　2008/11/13

DOI： 10.1380/ejssnt.2008.233 　

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Effects of CO adsorption on the magnetic properties of Fe films on Cu(001) were studied at 100 K as a function of the film thickness. CO adsorption does not affect the magnetic property of 2 ML Fe film but induces the spin reorientation transition from perpendicular to in-plane magnetization for 4 ML Fe film. It also causes the apparent decrease of magnetization, which is attributed to the reduction in surface magnetization by analyses of depth-resolved XMCD spectra. The reduction of the magnetization can be originated from a reconstruction of the surface structure of the films. It was suggested that the surface structures of the 4 ML Fe film are changed to a bcc-like structure upon CO adsorption, while the structure of the 2 ML Fe film could not change by CO adsorption because its magnetization is unchanged. © 2008 The Surface Science Society of Japan.
Huge perpendicular magnetic anisotropy of Fe single layer and spin-reorientation transitions observed in Fe/Co/Pd(111) films Peer-reviewed

ABE H,MIYAWAKI J,SAKO E.O,SAKAMAKI M,AMEMIYA K

Phys Rev B Condens Matter Mater Phys　78　(1)　014424.1-014424.6　2008/07

DOI： 10.1103/PhysRevB.78.014424 　

ISSN： 1098-0121
X-ray absorption fine structure spectroscopy study of arsenate adsorption on schwertmannite

Masako Sakamaki,Hirokazu Takahashi,Takehisa Konishi,Atsuyuki Inoue,Takashi Fujikawa

AIP Conference Proceedings　882　271-273　2007/03/26
Publisher: AIP
DOI： 10.1063/1.2644498 　

ISSN： 0094-243X

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We studied arsenate adsorption on schwertmannite by means of XAFS. Our results show that arsenate is bound to one or two iron octahedra and individual iron octahedra in schwertmannite become more regular after the adsorption. At the same time there is an increase of disorder in polymeric chains of iron octahedra. This suggests that the release of local strain is related to the overall stability of arsenate-adsorbed schwertmannite. © 2007 American Institute of Physics.

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Misc. 41

軟X線蛍光収量波長分散型XAS法によるCo薄膜表面の酸化過程のリアルタイム測定

阪田薫穂, 雨宮健太, 鈴木真粧子

日本放射光学会年会・放射光科学合同シンポジウム(Web)　34th　2021
8aB-1 Observation of BaTiO_3/Fe interface sate

Sakamaki Masako, Amemiya Kenta

Meeting abstracts of the Physical Society of Japan　69　(2)　646-646　2014/08/22
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
8aBF-2 Effects of electric field and chemical composition on magnetism of FeCo/BaTiO_3 thin films

Amemiya Kenta, Sakamaki Masako

Meeting abstracts of the Physical Society of Japan　69　(2)　287-287　2014/08/22
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
8aBF-1 Observation of BaTiO_3/Fe interface sate

Sakamaki Masako, Amemiya Kenta

Meeting abstracts of the Physical Society of Japan　69　(2)　286-286　2014/08/22
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aAY-6 XMCD observation of electric field-induced effect on Fe thin films

Sakamaki Masako, Amemiya Kenta

Meeting abstracts of the Physical Society of Japan　69　(1)　538-538　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aAY-7 Composition dependence in the electric-field effects for FeCo thin films

Amemiya Kenta, Sakamaki Masako

Meeting abstracts of the Physical Society of Japan　69　(1)　538-538　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aAY-6 XMCD observation of electric field-induced effect on Fe thin films

Sakamaki Masako, Amemiya Kenta

Meeting abstracts of the Physical Society of Japan　69　(1)　905-905　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aAY-7 Composition dependence in the electric-field effects for FeCo thin films

Amemiya Kenta, Sakamaki Masako

Meeting abstracts of the Physical Society of Japan　69　(1)　905-905　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Change of the structural strain and magnetic anisotropy in Pt/Co/Pt thin films by Ga^+irradiation

Sakamaki M., Amemiya K., Mazalski P., Sveklo I., Kurant Z., Maziewsku A., Liedke M.O., Fassbender J., Wawro A., Baczewski L.T.

Meeting abstracts of the Physical Society of Japan　68　(2)　831-831　2013/08/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Appearance of perpendicular magnetization in Pt/Co/Pt thin films by Ga^+ irradiation : Observation by depth-resolved XMCD technique

Amemiya K., Sakamaki M., Mazalski P., Sveklo I., Kurant Z., Maziewski A., Liedke M.O., Fassbender J., Wawro A., Baczewski L.T.

Meeting abstracts of the Physical Society of Japan　68　(2)　831-831　2013/08/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29aXZA-5 Magnetic anisotropy and magnetization curve of Ni/FeMn/Cu(100) thin films

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　68　(1)　1007-1007　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29aXZA-6 Effect of the structural strain on the magnetism of Fe layer in alternately-layered FeNi thin films

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　68　(1)　1007-1007　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29aXZA-6 Effect of the structural strain on the magnetism of Fe layer in alternately-layered FeNi thin films

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　68　(1)　563-563　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29aXZA-5 Magnetic anisotropy and magnetization curve of Ni/FeMn/Cu(100) thin films

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　68　(1)　563-563　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
18aFN-4 Effect of the surface structure on magnetic anisotropy of each layer in alternately-layered FeNi thin films

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　67　(2)　376-376　2012/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
18aFN-3 Magnetic anisotropy and magnetization curve of Ni/FeMn/Cu(100) thin films

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　67　(2)　375-375　2012/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
18aFN-4 Effect of the surface structure on magnetic anisotropy of each layer in alternately-layered FeNi thin films

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　67　(2)　811-811　2012/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
18aFN-3 Magnetic anisotropy and magnetization curve of Ni/FeMn/Cu(100) thin films

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　67　(2)　811-811　2012/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
27pCK-4 In-situ observation of magnetic anisotropy and surface structure of alternately-layered FeNi thin films

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　67　(1)　540-540　2012/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
27pCK-3 Effect of FeMn layers on magnetic anisotropy and coercivity of Ni/Cu(100) thin films

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　67　(1)　540-540　2012/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23pJB-11 Anomalous temperature dependence of remanent magnetization of Ni at the Cu/Ni interface

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　66　(2)　936-936　2011/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28aHE-5 Magnetic and film structure changes of CO adsorbed Fe/(Cu(001) films studied by XMCD, EXAFS

Abe H., Amemiya K., Sakamaki M., Kouzai S., Kondoh H.

Meeting abstracts of the Physical Society of Japan　66　(1)　513-513　2011/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23aJA-5 Local structural analysis of Al doped ZnO thin film by using Al K-edge XANES

Miyagawa Y,Ueda M,Sakamaki M,Nagamatsu S,Miki T,Maruyama T,Fujikawa T,Konishi T,Sakai M

Meeting Abstracts of the Physical Society of Japan　66　(0)　2011
Publisher: The Physical Society of Japan
24pRE-12 Polarization and excitation energy dependence of Plasmon satellites in Al 2s2p angular resolved core-level photoemission spectra

Miyagawa Y., Kawai N., Miki T., Kazama M., Ohori Y., Kaneko T., Konishi T., Shinotsuka H., Fujikawa T., Sumii R., Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　65　(2)　704-704　2010/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25pWL-9 Interface magnetic anisotropy study of Mo/Co/Au thin films

Sakamaki M., Amemiya K., Warwo A., Baczewski L. T., Kurant Z., Maziewki A.

Meeting abstracts of the Physical Society of Japan　65　(2)　424-424　2010/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25pWX-7 Temperature dependence of magnetization at the interface and inner layers of a Cu/Ni/Cu(100) thin film

Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　65　(2)　429-429　2010/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
20aPS-87 Electronic structure and anomalous properties of transition-metal oxides with a hollandite-type structure

Toriyama T., Konishi T., Sakamaki M., Ohta Y.

Meeting abstracts of the Physical Society of Japan　65　(1)　540-540　2010/03/01
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22pGL-8 Magnetic anisotropy study of Co/Au(111) films by using depth-resolved XMCD technique

Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　65　(1)　955-955　2010/03/01
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25aPS-116 K_2Cr_8O_<16> predicted as a half-metallic ferromagnet : Scenario for a metal-insulator transition

Sakamaki M., Konishi T., Ohta Y.

Meeting abstracts of the Physical Society of Japan　64　(2)　442-442　2009/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25pRA-3 Surface magnetic state change and structure of Fe/Cu(001) upon NO, CO adsorption

Abe H., Sakamaki M., Amemiya K., Kondoh H.

Meeting abstracts of the Physical Society of Japan　64　(2)　333-333　2009/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25pRA-7 Relation between atomic and magnetic structures in magnetic thin films (1) : Co/Ru (0001)

Amemiya K., Miyawaki J., Sakamaki M., Abe H., Sako E. O.

Meeting abstracts of the Physical Society of Japan　64　(2)　334-334　2009/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aTF-2 Depth-resolved XMCD observation of surface antiferromagnetic coupling of Fe/Cu(001) induced by NO adsorption

Abe H., Amemiya K., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　64　(1)　512-512　2009/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
30aTF-1 Temperature dependence of magnetization in the interface and inner layers of Cu/Ni/Cu(100) thin films

Amemiya Kenta, Sakamaki Masako, Abe Hitoshi

Meeting abstracts of the Physical Society of Japan　64　(1)　512-512　2009/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
20aXA-5 Temperature dependence of magnetic and atomic structures of the metal surface and inner layers

Amemiya Kenta, Sakamaki Masako

Meeting abstracts of the Physical Society of Japan　63　(2)　795-795　2008/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22pQA-1 First-principles calculation of the electronic structure of hollandite vanadate K_2V_8O_<16>

Sakamaki M., Horiuchi S., Konishi T., Ohta Y.

Meeting abstracts of the Physical Society of Japan　63　(2)　546-546　2008/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
20aXA-4 Observation of the magnetism of NO/Fe/Cu (001) films by using depth-resolved XMCD technique

Abe H., Sakamaki M., Amemiya K.

Meeting abstracts of the Physical Society of Japan　63　(2)　360-360　2008/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
20aXA-5 Temperature dependence of magnetic and atomic structures of the metal surface and inner layers

Amemiya Kenta, Sakamaki Masako

Meeting abstracts of the Physical Society of Japan　63　(2)　361-361　2008/08/25
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22aPS-44 XAFS analysis of Fe_3O_4 nanoparticles

Kitagami M., Sakamaki M., Kaneko T., Konishi T., Lin J.G., Lin L., Arvanitis D., Fujikawa T.

Meeting abstracts of the Physical Society of Japan　62　(2)　470-470　2007/08/21
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22aPS-62 Local structure and magnetic anisotropy of Au/Co/Au/W(110) thin film

Sakamaki M., Konishi T., Fujikawa T., Andersson C., Karis O., Arvanitis D., Holub-Krappe E., Rossner H. H.

Meeting abstracts of the Physical Society of Japan　62　(2)　474-474　2007/08/21
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
21aWD-2 Magnetic structure of Fe/Ni/Cu(100) thin films studied by a three-dimensional micro XMCD technique

Amemiya K., Abe H., Sako E., Miyawaki J., Sakamaki M.

Meeting abstracts of the Physical Society of Japan　62　(2)　430-430　2007/08/21
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
22pTD-5 Local Strain and Electronic States of Transparent Semiconductor ZnO and Al-doped ZnO

Sakamaki M,Sakai M,Konishi T,Kitagami M,Kaneko T,Arai H,Fujikawa T,Kitajima Y

Meeting Abstracts of the Physical Society of Japan　62　(0)　2007
Publisher: The Physical Society of Japan

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Research Projects 8

回折格子を用いた蛍光選別EXAFSによる軽元素の局所構造解析

雨宮健太, 阪田薫穂, 鈴木真粧子

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 挑戦的研究(萌芽)

Institution: 大学共同利用機関法人高エネルギー加速器研究機構

2022/06/30 - 2025/03/31
Multiscale 3D Magnetic Imaging with reflection-mode soft x-ray absorption spectroscopy

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Gunma University

2022/04/01 - 2025/03/31
波長分散型軟X線吸収分光法の高度化による表面化学反応のリアルタイムオペランド追跡

雨宮健太, 近藤寛, 鈴木真粧子, 阪田薫穂

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(A)

Institution: 大学共同利用機関法人高エネルギー加速器研究機構

2021/04/05 - 2025/03/31

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軟X線領域の蛍光収量波長分散型X線吸収分光装置を用いて，最大0.1気圧(10,000 Pa)のガス存在下で，表面化学反応のリアルタイム観察を行った。さらに，この手法に深さ分解X線吸収分光法(蛍光X線の出射角によって検出深度を制御し，深さ方向の情報を得る手法)を組み合わせて，深さ方向に進行する化学反応のリアルタイム深さ分解分析を実現した。この手法を用いて，コバルトの酸化反応を観察し，1 Pa程度の大気導入下においてはCo酸化物(Co3O4)が表面から0.5 nm程度の範囲で徐々に内部に浸透していくのに対し，大気を10 Pa導入することによって一気に1 nm近くまでCo3O4が生成する様子を明らかにした。また，Cuの酸化反応においては，500 Pa程度まではCuOが生成するのに対し，5,000 PaにするとCu2Oが徐々に生成することを見出し，これらの酸化物成分の深さ方向分布を解析している。一方，電気化学反応中の電極表面の観察に蛍光収量波長分散型X線吸収分光を適用した。厚さ200 nmのSi3N4膜にPt電極を蒸着し，真空と水溶液を仕切った状態で真空側からSi3N4膜を通して波長分散した軟X線を入射し，発生する蛍光X線を同じSi3N4膜を通して真空側の結像光学系で検出器上に結像することによって，電極表面のX線吸収スペクトルをリアルタイム測定した。電位の掃引に伴い，酸素の吸収端において新たなピークが出現し，その強度およびエネルギー位置が変化する様子を観察した。また，新たにCOMS検出器を導入し，バックグラウンドが従来の1/10以下に減少すること，および1秒以下の露光時間で連続測定が可能なことを確認した。
Theory of preformed pair states and nonequilibrium dynamics in materials with strong-coupling excitonic condensation

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: Chiba University

2020/04/01 - 2024/03/31
Development of depth-resolved soft X-ray absorption spectroscopy with fluorescence energy selection and observation of ionic conductor/ferro magnetic thin film interface Competitive

Suzuki-Sakamaki Masako, AMEMIYA Kenta

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Young Scientists (B)

2017/04 - 2019/03

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To observe the chemical/magnetic state of the ferromagnetic thin film interface under the electric field, we develop the fluorescence yield depth-resolved soft x-ray absorption spectroscopy that is based on the electron yield depth-resolved technique. Interface analysis with a nm-depth resolution has been realizes. In this study, we develop the high signal-to-background (S/B) ratio depth-resolved soft XAS by fluorescence energy selection. We finally succeed obtaining the Fe and Co fluorescence selective XAS spectra of the FeCo thin film, and realize 100-times enhancement of the S/B ratio.
繰り返しによらずに時空間を同時分解する軟X線イメージングスペクトロスコピーの開発 Competitive

雨宮健太

Offer Organization: 大学共同利用機関法人高エネルギー加速器研究機構

System: 挑戦的萌芽研究

2015/04 - 2017/03
マルチフェロイック特性を示す強磁性体・絶縁体接合における界面酸化物の機能解明 Competitive

酒巻真粧子

Offer Organization: 大学共同利用機関法人高エネルギー加速器研究機構

System: 若手研究(B)

2015/04 - 2017/03
強誘電体／強磁性体界面の電子状態と構造の深さ分解分析とそれを利用した磁性の制御 Competitive

雨宮健太

Offer Organization: 大学共同利用機関法人高エネルギー加速器研究機構

System: 基盤研究(B)

2013/04 - 2016/03

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