Updated on 2023/04/07
博士（工学） （ 2014.3 名古屋大学 ）
スピンデバイス
磁気記録
日本磁気学会
The Institute of Electrical and Electronics Engineers
電気学会 基礎・材料・共通部門 平成28年優秀論文発表賞
2016 電気学会 MnGa膜を用いたイオン照射型ビットパターン媒体の高密度化の検討
大島大輝
Spin-orbit torques in ferrimagnetic Gd/FeCo multilayers Reviewed
Yanai Shunsuke, Oshima Daiki, Takahashi Shigeki, Hirayama Yoshiyuki, Kato Takeshi
JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 62 ( SB ) 2023.3
Fabrication of beta-Mn type Co-Zn-Mn(001) film on MgO single crystal substrate Reviewed
Oshima Daiki, Kato Takeshi, Ikarashi Nobuyuki, Nagao Masahiro
AIP ADVANCES Vol. 13 ( 2 ) 2023.2
High performance of magnetically separable and recyclable photocatalyst of green-synthesized CoFe2O4/TiO2 nanocomposites for degradation of methylene blue Reviewed International coauthorship
Puspitarum Deska Lismawenning, Istiqomah Nurul Imani, Tumbelaka Rivaldo Marsel, Kusumaatmaja Ahmad, Oshima Daiki, Kato Takeshi, Suharyadi Edi
ADVANCES IN NATURAL SCIENCES-NANOSCIENCE AND NANOTECHNOLOGY Vol. 13 ( 4 ) 2022.12
High reusability of green-synthesized Fe3O4/TiO2 photocatalyst nanoparticles for efficient degradation of methylene blue dye Reviewed International coauthorship
Tumbelaka Rivaldo Marsel, Istiqomah Nurul Imani, Kato Takeshi, Oshima Daiki, Suharyadi Edi
MATERIALS TODAY COMMUNICATIONS Vol. 33 2022.12
Magneto-optical property and magnetic anisotropy of (100) oriented R0.5Bi2.5Fe5O12 (R = Eu, Sm, and Pr) thin films prepared by metal–organic decomposition Reviewed
R. Urakawa, W. Asano, M. Nishikawa, M. Kawahara, T. Nishi, D. Oshima, T. Kato, and T. Ishibashi
AIP Advances Vol. 12 page： 095322 2022.9
Magneto-optical property and magnetic anisotropy of (100) oriented R0.5Bi2.5Fe5O12 (R = Eu, Sm, and Pr) thin films prepared by metal-organic decomposition
Urakawa R., Asano W., Nishikawa M., Kawahara M., Nishi T., Oshima D., Kato T., Ishibashi T.
AIP ADVANCES Vol. 12 ( 9 ) 2022.9
Electric-Field Modulation of Perpendicular Magnetic Anisotropy and Damping Constant in MgO/Co/Pt Trilayers
Sakoguchi A., Oshima D., Iwata S., Kato T.
IEEE TRANSACTIONS ON MAGNETICS Vol. 58 ( 2 ) 2022.2
Effect of substrate temperature on plasma-enhanced self-assembling formation of high-density FePt nanodots
Honda Shunsuke, Makihara Katsunori, Taoka Noriyuki, Furuhata Hiroshi, Ohta Akio, Oshima Daiki, Kato Takeshi, Miyazaki Seiichi
JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 61 ( SA ) 2022.1
Enhancement of spin-orbit torques by change in uniaxial in-plane magnetic anisotropy of Py/Pt bilayers on single crystal 128 degrees Y-Cut LiNbO3 substrate Reviewed
Ito Masayoshi, Yamaguchi Akinobu, Oshima Daiki, Kato Takeshi, Shima Mutsuhiro, Yamada Keisuke
APPLIED PHYSICS LETTERS Vol. 119 ( 15 ) 2021.10
Crystal Structure and Magnetic and Magneto-optical Properties of CoPt, MnPt3, CrPt3, MnAl and MnGa Films with Ordered Phase and Their Bit-patterned Media Invited Reviewed
S. Iwata, T. Kato, D. Oshima
Journal of the magnetics society of Japan Vol. 45 ( 5 ) page： 118 - 124 2021.9
Topotactic crystal structure transformation from spinet ferrite to wustite in epitaxial Fe3O4 films via Kr ion irradiation Reviewed
Liu Yang, Hisamatsu Yuki, Sharmin Sonia, Oshima Daiki, Iwata Satoshi, Kato Takeshi, Sekiba Daiichiro, Kita Eiji, Yanagihara Hideto
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A Vol. 39 ( 3 ) 2021.5
Progress on efficient current-induced magnetization switching
Kato Takeshi, Iwata Satoshi, Oshima Daiki
ELECTRICAL ENGINEERING IN JAPAN Vol. 212 ( 1-4 ) page： 3 - 10 2020.9
Spin orbit torques in ferrimagnetic GdFeCo with various compositions Reviewed
Kawakami Keisuke, Kato Takeshi, Oshima Daiki, Iwata Satoshi
JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 59 2020.4
Highly (001) oriented MnAl thin film fabricated on CoGa buffer layer Reviewed
Oshima Daiki, Kato Takeshi, Iwata Satoshi
AIP ADVANCES Vol. 10 ( 2 ) 2020.2
Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers Reviewed
Zhao Wangzhen, Kimura Takumi, Kato Takeshi, Oshima Daiki, Sonobe Yoshiaki, Takahashi Shigeki, Iwata Satoshi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 493 2020.1
Patterned arrays of assembled nanoparticles prepared by interfacial assembly and femtosecond laser fabrication
Jiang Chengpeng, Oshima Daiki, Iwata Satoshi, Pong Philip W. T., Kato Takeshi
JOURNAL OF NANOPARTICLE RESEARCH Vol. 22 ( 1 ) 2019.12
MnGa (001)-Textured Film Fabricated on Thermally Oxidized Si Substrate for Application to Ion Beam Bit Patterned Media
Ishikawa Toru, Miwa Yoshitsugu, Oshima Daiki, Kato Takeshi, Iwata Satoshi
IEEE TRANSACTIONS ON MAGNETICS Vol. 55 ( 7 ) 2019.7
Ion Irradiation for Planar Patterning of Magnetic Materials
Kato Takeshi, Oshima Daiki, Iwata Satoshi
CRYSTALS Vol. 9 ( 1 ) 2019.1
Variation of Magnetization Dynamics of Co/Ni Multilayer by Capturing Magnetic Nanoparticles Reviewed
Otaki Y., Kato T., Okamoto S., Kikuchi N., Oshima D., Iwata S., Kitakami O.
IEEE TRANSACTIONS ON MAGNETICS Vol. 54 ( 11 ) 2018.11
Hybrid Memory Layer With Low Curie Temperature CoPd/Pd Multilayer for High-Density Magnetic Random-Access Memory Cells Reviewed
Zhao W., Dong X., Kimura T., Kato T., Oshima D., Sonobe Y., Kawato Y., Iwata S.
IEEE TRANSACTIONS ON MAGNETICS Vol. 54 ( 11 ) 2018.11
Spin transfer torque switching of Co/Pd multilayers and Gilbert damping of Co-based multilayers
Kimura Takumi, Dong Xiayin, Adachi Kanta, Oshima Daiki, Kato Takeshi, Sonobe Yoshiaki, Okamoto Satoshi, Kikuchi Nobuaki, Kawato Yoshiaki, Kitakami Osamu, Iwata Satoshi
JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 57 ( 9 ) 2018.9
Femtosecond resonant magneto-optical Kerr effect measurement on an ultrathin magnetic film in a soft X-ray free electron laser Reviewed
Yamamoto Shingo, Kubota Yuya, Yamamoto Kohei, Takahashi Yoshinobu, Maruyama Kohei, Suzuki Yuta, Hobara Rei, Fujisawa Masami, Oshima Daiki, Owada Shigeki, Togashi Tadashi, Tono Kensuke, Yabashi Makina, Hirata Yasuyuki, Yamamoto Susumu, Kotsugi Masato, Wadati Hiroki, Kato Takeshi, Iwata Satoshi, Shin Shik, Matsuda Iwao
JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 57 ( 9 ) 2018.9
Spin-valve giant magneto-resistance film with magnetostrictive FeSiB amorphous layer and its application to strain sensors Reviewed
Hashimoto Y., Yamamoto N., Kato T., Oshima D., Iwata S.
JOURNAL OF APPLIED PHYSICS Vol. 123 ( 11 ) 2018.3
Switching Field Distribution of MnGa Bit Patterned Film Fabricated by Ion Beam Irradiation Reviewed
Oshima D., Kato T., Iwata S.
IEEE TRANSACTIONS ON MAGNETICS Vol. 54 ( 2 ) 2018.2
Hybrid memory layer with low Curie temperature CoPd/Pd multilayer for high-density magnetic random access memory cells
Zhao W., Kimura T., Kato T., Oshima D., Sonobe Y., Kawato Y., Iwata S.
2018 IEEE INTERNATIONAL MAGNETIC CONFERENCE (INTERMAG) 2018
Nano spin-diodes using FePt-NDs with huge on/off current ratio at room temperature Reviewed
K. Makihara, T. Kato, Y. Kabeya, Y. Mitsuyuki, A. Ohta, D. Oshima, S. Iwata, Y. Darma, M. Ikeda, S. Miyazaki
Scientific Reports Vol. 6 page： 33409 2016.9
Ferromagnetic Resonance of a Single Magnetochiral Metamolecule of Permalloy Reviewed
T. Kodama, S. Tomita, T. Kato, D. Oshima, S. Iwata, S. Okamoto, N. Kikuchi, O. Kitakami, N. Hosoito, H. Yanagi
Physical Review Applied Vol. 6 page： 024016-1-9 2016.8
Effective Damping Constant and Current Induced Magnetization Switching of GdFeCo/TbFe Exchange-Coupled Bilayers Reviewed
T. Higashide, B. Dai, T. Kato, D. Oshima, S. Iwata
Vol. 7 page： 3505605 2016.7
Nanoscale patterning of CrPt3 magnetic thin films by using ion beam irradiation Reviewed
E. Suharyadi, D. Oshima, T. Kato, S. Iwata
Results in Physics Vol. 6 page： 186-188 2016.4
Ion irradiation induced magnetic transition of MnGa alloy films studied by X-ray magnetic circular dichroism and low-temperature hysteresis loops Reviewed
D. Oshima, M. Tanimoto, T. Kato, Y. Fujiwara, T. Nakamura, Y. Kotani, S. Tsunashima, S. Iwata
IEEE Transactions on Magnetics Vol. 52 ( 7 ) page： 3201804-1-4 2016.2
Structure and Magnetic Properties of (001) Oriented CoPt-Ag and CoPd-Ag Alloy Films Reviewed
T. Nagata, Y. Tokuoka, T. Kato, D. Oshima, S. Iwata
Journal of Magnetics Society of Japan Vol. 40 ( 1 ) page： 13-17 2016.1
Anomalous structural behavior in the metamagnetic transition of FeRh thin films from a local viewpoint Reviewed
Y. Wakisaka, Y. Uemura, T. Yokoyama, H. Asakura, H. Morimoto, M. Tabuchi, D. Oshima, T. Kato, S. Iwata
Physical Review B Vol. 92 page： 184408 2015.11
Magnetization control for bit pattern formation of spinel ferromagnetic oxides by Kr ion implantation Reviewed
E. Kita, K. Z. Suzuki, Y. Liu, Y. Utsumi, J. Morishita, D. Oshima, T. Kato, T. Niizeki, K. Mibu, H. Yanagihara
Journal of Applied Physics Vol. 115 page： 17B907 2014
Control of magnetic properties of MnGa films by Kr+ ion irradiation for application to bit patterned media Reviewed
D. Oshima, T. Kato, S. Iwata, S. Tsunashima
IEEE Transactions on Mgnetics Vol. 49 ( 7 ) page： 3608-3611 2013
Observation of ferri-nonmagnetic boundary in CrPt3 line-and-space patterned media using a dark-field transmission electron microscope Reviewed
D. Oshima, E. Suharyadi, T. Kato, S. Iwata
Journal of Magnetism and Magnetic Materials Vol. 324 page： 1617-1621 2012
Switching field distribution of planar-patterned CrPt3 nanodots fabricated by ion irradiation Reviewed
E. Suharyadi, D. Oshima, T. Kato, S. Iwata
Journal of Applied Physics Vol. 109 page： 07B771 2011
Fabrication of L12-CrPt3 Alloy Using Rapid Thermal Annealing for Planar Bit Patterned Media Reviewed
T. Kato, D. Oshima, Y. Yamauchi, S. Iwata, S. Tsunashima
IEEE Transactions on Magnetics Vol. 46 ( 6 ) page： 1671-1674 2010
ビスマス置換磁性ガーネットの磁気回転比向上に関する研究
朝野航，西敬生，大島大輝，加藤剛志，李基鎮，河原正美，西川雅美，石橋隆幸
第70回応用物理学会春季学術講演会 2023.3.17
Fabrication of beta-Mn type CoZnMn(001) film on MgO single crystal substrate International conference
D. Oshima, R. Mitsuhashi, N. Ikarashi, T. Kato, M. Nagao
The 67th Annual Conference on Magnetism and Magnetic Materials 2022.11.3
MgO/CoFe/Pt積層膜の磁気異方性とダンピング定数の熱処理による変化
小西愉真，大島大輝，加藤剛志
第46回日本磁気学会学術講演会 2022.9.6
Ta上に積層したGd/FeCo多層膜のスピン軌道トルク
矢内峻介，大島大輝，高橋茂樹，平山義幸，加藤剛志
第46回日本磁気学会学術講演会 2022.9.8
ひずみ印加による FeSiBNb 薄膜の磁化制御とパルス電圧の観測
沓名勇輝，藤原裕司，大島大輝，加藤剛志，神保睦子
第46回日本磁気学会学術講演会 2022.9.7
Fe-Ga-M薄膜の磁気特性と熱処理温度の影響
鈴木和歩，藤原裕司，大島大輝，加藤剛志，神保睦子
第46回日本磁気学会学術講演会 2022.9.6
逆位相で磁化変調したフィードバック型GMRセンサの作製
小室虎祐，大島大輝，加藤剛志
第46回日本磁気学会学術講演会 2022.9.6
超短パルス光により励起したFeCo/Cu/GdFeCo三層膜の磁化ダイナミクス
瀬口和也，大島大輝，加藤剛志
第46回日本磁気学会学術講演会 2022.9.6
強磁性共鳴測定による EuBi2Fe5-xGaxO12薄膜の評価
朝野航，西敬生，大島大輝，加藤剛志，李基鎮，河原正美，西川雅美，石橋隆幸
第46回日本磁気学会学術講演会 2022.9.6
単結晶基板上にエピタキシャル成長したβ-Mn型CoZnMn薄膜
大島大輝，三橋良祐，五十嵐信行，加藤剛志，長尾全寛
第46回日本磁気学会学術講演会 2022.9.6
Photocatalytic Activity of Green-Synthesized Fe3O4/TiO2 Magnetic Nanoparticles International conference
R. M. Tumbelaka, N. I. Istiqomah, T. Kato, D. Oshima, E. Suharyadi
2nd International Conference on Magnetism and Its Applications 2022.6.3
Spin Orbit Torques in Ferrimagnetic Gd/FeCo Multilayers International conference
S. Yanai, D. Oshima, S. Takahashi, Y. Hirayama, T. Kato
Magnetics and Optics Research International Symposium 2022 2022.5.18
Magnetization Dynamics of GdFeCo/Cu/FeCo Trilayers Triggered by Ultrashort Pulsed Laser International conference
K. Seguchi, D. Oshima, T. Kato
Magnetics and Optics Research International Symposium 2022 2022.5.17
高TC/低TCハイブリッド層のスピン移行トルク磁化反転における界面高TC層の影響
趙望臻，加藤剛志，大島大輝，岩田聡
マグネティックス研究会 2022.3.4
GdFeCo/Cu/FeCo三層膜の超短パルス光誘起磁化ダイナミクス
瀬口和也，大島大輝，加藤剛志
IEEE Magnetics Society名古屋支部若手研究会 2022.2.2
LiNbO3単結晶基板上のPy/Pt薄膜における面内一軸磁気異方性とスピン軌道トルクの相関解明
伊藤将慶，山口明啓，大島大輝，加藤剛志，嶋睦宏，山田啓介
IEEE Magnetics Society名古屋支部若手研究会 2022.2.2
Effect of high TC interface layer in high TC/ low TC hybrid memory layer on thermally assisted spin-transfer-torque switching International conference
W. Zhao, T. Kato, D. Oshima, S. Iwata
The 15th Joint MMM-INTERMAG Conference 2022.1 IEEE
β-Mn型CoZnMnエピタキシャル薄膜の作製
大島大輝,三橋良祐,五十嵐信行,加藤剛志,長尾全寛
マグネティックス研究会 2021.12.2 電気学会
Fabrication of epitaxially grown β-Mn type CoZnMn film International conference
D. Oshima, M. Kawai, R. Mitsuhashi, S. Hirata, N. Ikarashi, T. Kato, M. Nagao
International Confernce on Materials and Systems for Sustainability 2021 2021.11.5
Enhancement of spin-orbit torques using change of uniaxial in-plane magnetic anisotropy in Py/Pt bilayers on a single crystal Y-Cut 128° LiNbO3 substrate International conference
M. Ito, A. Yamaguchi, D. Oshima, T. Kato, M. Shima, K. Yamada
International Confernce on Materials and Systems for Sustainability 2021 2021.11.5 IMaSS
Magnetic anisotropy of highly bismuth-substituted rare-earth (Y, Pr, Nd, Sm and Er) iron garnet thin films International conference
T. Ishibashi, R. Urakawa, M. Nishikawa, T. Nishi, D. Oshima, T. Kato
International Confernce on Materials and Systems for Sustainability 2021 2021.11.5 IMaSS
The study of interface layer in hybrid memory layer for thermally assisted STT-MRAM cells International conference
W. Zhao, T. Kato, D. Oshima, S. Iwata
International Confernce on Materials and Systems for Sustainability 2021 2021.11.5 IMaSS
高TC/低TCハイブリッド層を用いた熱アシストSTT磁化反転における界面高TC層の影響
趙望臻，加藤剛志，大島大輝，岩田聡
第45回日本磁気学会学術講演会 2021.9.1 日本磁気学会
LiNbO3単結晶基板上の2層構造Py/Ptにおける面内一軸磁気異方性によるスピン軌道トルクの変化
伊藤将慶，山口明啓，大島大輝，加藤剛志，嶋睦宏，山田啓介
第45回日本磁気学会学術講演会 2021.9.1 日本磁気学会
グラニュラー薄膜を用いたひずみセンサの開発
上野駿平，天満光佑，上部智也，藤原裕司，大島大輝，加藤剛志，神保睦子
第45回日本磁気学会学術講演会 2021.9.2 日本磁気学会
Electric-field modulation of perpendicular magnetic anisotropy and damping constant in MgO/Co/Pt trilayers International conference
A. Sakoguchi, T. Kato, D. Oshima, S. Iwata
INTERMAG 2021 Conference 2021.4.29 IEEE
ビットパターン媒体に用いるSi基板上MnGa (001)配向膜の作製
三輪佳嗣，石川徹，大島大輝，加藤剛志，岩田聡
第42回日本磁気学会学術講演会
低キュリー温度CoPd/Pd系多層膜を用いたMRAM用交換結合ハイブリッドメモリ層
趙望臻，木村匠，董夏茵，大島大輝，加藤剛志，園部義明，川戸良昭，岩田聡
第42回日本磁気学会学術講演会
Co/Pd多層膜のスピン注入磁化反転臨界電流の層厚比依存性
趙望臻，木村匠，大島大輝，加藤剛志，園部義明，川戸良昭，岩田聡
第42回日本磁気学会学術講演会
CoGa下地層を用いた極薄L10-MnGa膜の磁気パターニング
堀江祐貴，三輪佳嗣，大島大輝，加藤剛志，岩田聡
第42回日本磁気学会学術講演会
Fe3O4 / Cr 多層膜における垂直磁気異方性
大島大輝，加藤剛志，岩田聡
第42回日本磁気学会学術講演会
Ion beam patterning of ultrathin L10-MnGa (001) film grown on CoGa buffer layer International conference
Y. Horie, D. Oshima, T. Kato, S. Iwata
IEEE International Magnetics Conference 2018
Scanning X-ray magnetic circular dichroism observation of magnetic state of ion-irradiation bit patterned L10-MnGa films International conference
T. Ishikawa, K. Fukuta, D. Oshima, T. Kato, T. Nakamura, Y. Kotani, K. Toyoki, S. Iwata
International Conference on Materials and Systems for Sustainability
走査型XMCD顕微鏡によるイオン照射型L10-MnGaビットパターン膜の局所的磁気状態の評価
石川徹，福田憲吾，大島大輝，加藤剛志，中村哲也，小谷佳範，豊木研太郎，岩田聡
第41回日本磁気学会学術講演会
イオン照射により作製したMnGaビットパターン膜のFORC解析
大島大輝，加藤剛志，岩田聡
第41回日本磁気学会学術講演会
Ion Beam Bit Patterned Media Using MnGa Alloy Films Invited International conference
D. Oshima, T. Kato, S. Iwata
The 28th Magnetic Recording Conference
First order reversal curve diagram analysis of ion irradiated bit patterned MnGa film International conference
D. Oshima, T. Kato, S. Iwata
IEEE International Magnetics Conference 2017
Ion irradiation induced magnetic transition of MnGa alloy films studied by X-ray magnetic circular dichroism and low-temperature hysteresis loops International conference
D. Oshima, M. Tanimoto, T. Kato, Y. Fujiwara, T. Nakamura, Y. Kotani, S. Tsunashima, S. Iwata
2016 Joint MMM-Intermag Conference
Control of Magnetic Inactivation Layer Thickness in MnGa Film by Kr Ion Irradiation International conference
D. Oshima, T. Kato, S. Takahashi, Y. Sonobe, S. Iwata, S. Tsunashima
20th International Conference on Magnetism
(001) Oriented MnGa Film Grown on Si Substrate for Ion Beam Patterned Media International conference
D. Oshima, T. Negoro, T. Kato, S. Iwata, S. Tsunashima
20th International Conference on Magnetism
Anisotropic X-ray magnetic circular dichroism spectra of (001) oriented L10-MnGa film International conference
D. Oshima, M. Tanimoto, T. Kato, Y. Fujiwara, T. Nakamura, Y. Kotani, S. Tsunashima, S. Iwata
IEEE International Magnetics Conference 2015
Magnetic circular dichroism measurement of ion irradiated MnGa films International conference
D. Oshima, M. Tanimoto, T. Kato, Y. Fujiwara, T. Nakamura, Y. Kotani, S. Tsunashima, S. Iwata
IEEE International Magnetics Conference 2014
Grant number：21H01029 2021.4 - 2024.3
科学研究費助成事業 基盤研究(B)
長尾 全寛, 大島 大輝
Authorship：Coinvestigator(s)
磁気スキルミオンは安定な粒子として振る舞い、超低密度電流駆動を示すことからスキルミオンを情報キャリアとして利用する応用的価値に注目が集まっている。特に、スキルミオン間相互作用が存在する高密度スキルミオンの集団的運動は、非圧縮性トポロジカル粒子流という分野横断的な舞台を提供する可能性があり、デバイス応用を目指す上でもその解明は重要である。本研究では、高密度スキルミオンの集団的運動の特性を流体力学的アプローチによって解明する。特に、高密度スキルミオンの集団的運動はスキルミオン間相互作用に起因するスキルミオン粘性流の発現が見込まれ、超高速駆動やホール粘性などの新規輸送特性の観測が期待される。
空間対称性の破れの制御によるスピン軌道トルクの増強と3次元メモリへの展開
Grant number：20H02182 2020.4 - 2023.3
科学研究費助成事業 基盤研究(B)
加藤 剛志, 大島 大輝
Authorship：Coinvestigator(s)
スピン軌道トルク（SOT）磁化反転は磁性層に隣接する非磁性層に電流を流すことで磁化反転を行なうもので，既存のスピン移行トルク（STT）磁化反転に比べ1/5程度の消費電力で10倍高速に磁化反転ができると考えら，今後のSociety 5.0を支える大容量磁気ランダムアクセスメモリ（MRAM）への応用研究が進められている．本研究は磁性材料に空間反転対称性の破れを人工的に導入することで，SOT磁化反転の高効率化を図るとともに，これを利用した3次元メモリの原理実証を行なう．
本年度は膜厚方向に構造変調を加え，人工的に空間反転対称性を破ったGd/FeCo多層膜をマグネトロンスパッタ法により作製し，その磁気特性の評価を行うとともに2~10 um幅のHallクロス形状に微細加工し，スピン軌道トルクおよびスピン軌道トルク磁化反転の膜構成依存性を調べた．膜厚方向に組成勾配のないGd/FeCoから徐々に組成勾配を大きくした4種のサンプルを用意し，全てのサンプルで平均組成がほぼ同じとなっていることを確認した．膜厚方向に組成勾配のないGd/FeCo多層膜のスピン軌道トルクを測定し，ダンピングライクトルク，フィールドライクトルクの有効磁場は補償組成付近で大きくなること，フィールドライクトルクの符号は補償組成を挟んで変化することを確認した．この傾向はGdFeCo合金と同様であり，Gd/FeCo多層膜でも，GdFeCo合金と同様のスピン軌道トルクが得られた．膜厚方向に組成勾配のあるGd/FeCo多層膜の磁化反転の臨界電流の面内磁場依存性を測定し，全ての膜でおおよそ10 MA/cm2程度の反転電流密度が観測された．膜厚方向の組成勾配を増加させることにより若干の反転電流密度の低下が観測されたが，有意な差か否かについて，より詳細に検討する必要があることが分かった．また，Gd/FeCo多層膜に比べ微細加工が容易なCo/Pd系多層膜をメモリ層とする巨大磁気抵抗効果型接合を作製し，スピン移行トルクによる磁化反転を確認した．
本年度予定していた膜厚方向に構造変調を加え人工的に空間反転対称性を破ったGd/FeCo多層膜を作製し，そのスピン軌道トルク測定を行った．また，Co/Pd多層膜をメモリ層とする巨大磁気抵抗効果型接合を作製し，スピン移行トルクによる磁化反転を確認するなど，3次元メモリ原理実証の検討も順調に進んだ．本研究の目的達成にはより多くのサンプルについて検討を進める必要があるが，おおむね順調に進展していると考えられる．
昨年度に引き続き，膜厚方向に構造変調を加え，人工的に空間反転対称性を破ったGd/FeCo多層膜を作製し，スピン軌道トルク，ジャロシンスキー守谷（DMI）相互作用を計測する．昨年度は補償組成近傍のGd/FeCo多層膜（全膜厚5 nm）のみであったが，本年度は希土類リッチ側から遷移金属リッチ側まで組成を変更すること，全膜厚を変化させるなど，空間反転対称性の効果を網羅的に検討する．更にTb/FeCo/Gd多層膜も作製し，希土類元素内にも構造変調を加えた場合についても計測を進める．Co/Pd系多層膜を含む3次元メモリ構造はスピン移行トルクとスピン軌道トルクを同時印加することによる磁化反転を試み，3次元メモリの原理実証を進める．
Grant number：19K15044 2019.4 - 2021.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists
Oshima Daiki
Authorship：Principal investigator
Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）
For application to voltage-driven magnetic memories, ferromagnetic-oxide / ferromagnetic-metal / nonmagnetic metal repetition layer structure was fabricated by magnetron sputtering method, and the magnetic property and the crystal structure of the samples were evaluated. Zn ferrite, used as a ferromagnetic-oxide, was epitaxially grown on ferromagnetic FeCo / nonmagnetic W buffer layers. Perpendicular magnetic anisotropy, which is important for memory applications, was confirmed in the repetition multilayer. There is the possibility that the proposed structure is available in the magnetic memories.
Magnetization switching by spin current induced by ultra short pulse laser
Grant number：17K18878 2017.6 - 2019.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
Kato Takeshi
Authorship：Coinvestigator(s)
In order to observe spin current generation by the ultra short pulse laser and the magnetization switching by the spin current, two experiments, 1) spin current injection to Au from 3d transition metal Fe and 2) magnetization switching of GdFeCo by injecting the spin current, were carried out. Fe thickness dependence of the damping constant of Fe showed the Au layer has useful properties as a spin current conductor. When the spin current injected to GdFeCo, the moment of GdFeCo feels large equivalent magnetic field around the compensation composition. Moreover, it was found that the injected spin current exerts a torque to only FeCo moment.
Local magnetization control using spin Hall effect and its application to GMR magnetic sensors
Grant number：17H03249 2017.4 - 2020.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Iwata Satoshi
Authorship：Coinvestigator(s)
In this research project, we have developed strain-sensor using giant magnetoresistance effect, where inverse magneto-striction effect is applied to the magnetic free layer in a spin valve structure. In order to avoid from influence of magnetic stray field, we employ sinusoidal signal detection method, where the magnetization direction of the magnetic free layer was modulated by alternative magnetic field by flowing AC current through Al strip line formed on GMR element. In next stage, we have investigated magnetization control by spin-Hall effect. The sensor device is composed from Ta/FeCo layer for producing spin current, a magnetoresistive spin-valve element and anti-ferromagneic NiO layer which magnetically connects Ta/FeCo and spin-valve layers. In this device, magnetization reversal by spin Hall effect was observed.
Control of spin dynamics by electric field and electric-field-assisted spin Hall switching
Grant number：16H04328 2016.4 - 2019.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Kato Takeshi
Authorship：Coinvestigator(s)
Spin Hall switching is considered as a promising way of the next generation writing scheme of the magnetic random access memories. This study focused on the effect of the applied electric field on the spin Hall switching of Co and Fe ultrathin films, where the electric field was applied thorough HfO2/MgO insulation layer. Moreover, the effect of the electric field on the spin dynamics was also studied. The coercivity and current density of the spin Hall switching were modified by the electric field as 43 %/(V/m) and 20 %/(V/m), respectively. The modifications of the coercivity and the current density of the spin Hall switching by the electric field were found to be sensitive to the deposition condition of the insulation layer.
Control of magnonic crystal by voltage
Grant number：16K18091 2016.4 - 2018.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
OSHIMA Daiki
Authorship：Principal investigator
Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）
Development of materials was carried out in order to control spin wave by using periodic nano-sized electrodes. First, voltage was applied to the fabricated samples, however, the voltage effect was not obtained. Thinning the sample was tried because it was effective to obtain a voltage effect. As a result, thinning the sample without degrading the property of the sample was successful. In addition, a multilayered structure of ferromagnetic insulator / ferromagnetic metal / nonmagnetic metal was suggested as a new system for voltage application, and the prototype of the structure was fabricated. It was found that the fabricated structure had a perpendicular magnetic anisotropy. In the future, micro-fabrication process will be optimized and the experiment for voltage application will be carried out.
電気電子情報工学実験第１
2022
電気電子情報工学実験第２
2022
電気磁気学基礎演習
2015
電気電子工学実験
2015
電気磁気学基礎演習
2014
電気電子工学実験
2014
