磁性絶縁体/金属ナノ構造におけるスピンホール磁気抵抗効果の理論的研究

2015 Fiscal Year Annual Research Report

• Project/Area Number: 25400337
• Research Institution: Tohoku University
• Principal Investigator: 高橋 三郎 東北大学, 金属材料研究所, 助教 (60171485)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: スピンホール磁気抵抗効果 / スピン流 / スピンホール効果 / スピン依存ホール効果 / 強磁性絶縁体 / 強磁性金属 / ナノ構造２層膜

Outline of Annual Research Achievements

本研究は、強磁性絶縁体を用いたナノ構造複合膜において、非平衡スピン流とスピンホール効果に起因した新規な磁気抵抗効果を提案し、そのスピン伝導理論を構築した。この磁気抵抗効果は国内外で実験的に検証され、「スピンホール磁気抵抗効果」と呼ばれている。最終年度は、強磁性金属を用いたナノ構造複合膜への拡張を行った。
強磁性金属とスピン軌道相互作用の強い金属からなるナノ構造２層膜において、大きなスピンホール磁気抵抗効果が起こることを理論的に明らかにした。電気を通す強磁性金属を用いると、スピンホール効果によって非磁性金属層に生じたスピン流は、強磁性金属の磁化の向きに依存して、横偏極成分のみならず縦偏極成分のスピン流が強磁性金属に吸収される。また、強磁性金属層に電流が流れることにより、強磁性金属にスピン依存ホール効果が生じて磁化の向きに依存した縦偏極成分のスピン流が生成され、強磁性金属層にもスピンホール磁気抵抗効果が生じる。このため、強磁性金属を用いた金属系２層膜のスピンホール磁気抵抗効果は、強磁性絶縁体を用いた絶縁体系２層膜と比べて異なった振舞いを示す。最終年度では、強磁性金属層のスピン依存ホール効果及び縦の界面スピン流の影響を解明し、金属系の２層膜で発現するスピンホール磁気抵抗の磁化の角度依存性や膜厚依存性を解析する理論を構築した。これにより、非磁性金属層のスピンホール角、強磁性金属層のスピン依存ホール角、スピン分極率を見積もることが可能になった。実験グループとの共同研究により、コバルト鉄ボロン（CoFeB）強磁性金属とタングステン（W）金属を用いた２層膜において、絶縁体系２層膜に比べて１０倍ほど大きなスピンホール磁気抵抗効果が発現することを実験的に観測することに成功した。

Research Products

• [Int'l Joint Research] Walther-Meisner-Institut/Technische Universitat Munchen(Germany)
  • Country Name: Germany
  • Counterpart Institution: Walther-Meisner-Institut/Technische Universitat Munchen
• [Journal Article] Spin hydrodynamic generation (2016)
  • Author(s): R. Takahashi, M. Matsuo, M. Ono, K. Harii, H. Chudo, S. Okayasu, J. Ieda, S. Takahashi, S. Maekawa, and E. Saitoh
  • Journal Title: Nature Physics Volume: 12 Pages: 52-56
  • DOI: 10.1038/nphys3526
  • Peer Reviewed
• [Journal Article] Spin Hall magnetoresistance in metallic bilayers (2016)
  • Author(s): J. Kim, P. Sheng, S. Takahashi, S. Mitani, and M. Hayashi
  • Journal Title: Phys. Rev. Lett. Volume: 116 Pages: 097201(1-5)
  • DOI: 10.1103/PhysRevLett.116.097201
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Effective exchange fields in spin-torque resonance of magnetic insulators (2016)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Journal Title: J. Magn. Magn. Mater. Volume: 400 Pages: 163-167
  • DOI: 10.1016/j.jmmm.2015.07.058
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Theory of spin Hall magnetoresistance (SMR) and related phenomena (2016)
  • Author(s): Y.-T. Chen, S. Takahashi, H. Nakayama, M. Althammer, S. T. B. Goennenwein, E. Saitoh, and G. E. W. Bauer
  • Journal Title: J. Phys.: Condens. Matter Volume: 28 Pages: 103004(1-15)
  • DOI: 10.1088/0953-8984/28/10/103004
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Temperature dependence of enhanced spin relaxation time in metallic nanoparticles: Experiment and theory (2016)
  • Author(s): T. Koda, S. Mitani, S. Takahashi, M. Mizuguchi, K. Sato, T. J. Konno, S. Maekawa, and K. Takanashi
  • Journal Title: Phys. Rev. B Volume: 93 Pages: 085402(1-7)
  • DOI: 10.1103/PhysRevB.93.085402
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Modelling of the Peltier effect in magnetic multilayers (2016)
  • Author(s): I. Juarez-Acosta, M. A. Olivares-Robles, S. Bosu, Y. Sakuraba, T. Kubota, S. Takahashi, K. Takanashi, and G. E. W. Bauer
  • Journal Title: J. Appl. Phys. Volume: 119 Pages: 073906(1-11)
  • DOI: 10.1063/1.4942163
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Quasiparticle-mediated spin Hall effect in a superconductor (2015)
  • Author(s): T. Wakamura, H. Akaike, Y. Omori, Y. Niimi, S. Takahashi, A. Fujimaki, S. Maekawa, and Y. Otani
  • Journal Title: Nature Materials Volume: 14 Pages: 675－679
  • DOI: 10.1038/NMAT4276
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Magnetization damping in antiferromagnetically coupled spin valves via dynamical spin transfer toque (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Journal Title: Phys. Rev. B Volume: 92 Pages: 054407(1-9)
  • DOI: 10.1103/PhysRevB.92.054407
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Current-induced spin torque resonance of a magnetic insulator (2015)
  • Author(s): M. Schreier, T. Chiba, A. Niedermayr, J. Lotze, M. Lammel, H. Huebl, S. Geprags, S. Takahashi, G. E. W. Bauer, R. Gross, and S. T. B. Goennenwein
  • Journal Title: Phys. Rev. B Volume: 92 Pages: 144411(1-6)
  • DOI: 10.1103/PhysRevB.92.144411
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Size dependence of Peltier cooling in ferromagnet|Au nano-pillars (2015)
  • Author(s): S. Bosu, Y. Sakuraba, T. Kubota, I. Juarez-Acosta, T. Sugiyama, K. Saito, M. A. Olivares-Robles, S. Takahashi, G. E. W. Bauer, and K. Takanashi
  • Journal Title: Appl. Phys. Express Volume: 8 Pages: 083002(1-4)
  • DOI: 10.7567/APEX.8.083002
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings, (2016)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: The 13th Joint MMM-Intermag Conference
  • Place of Presentation: San Diego, USA
  • Year and Date: 2016-01-11 – 2016-01-15
  • Int'l Joint Research
• [Presentation] Effective exchange fields in spin-torque resonance of magnetic insulators (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: 13th RIEC International Workshop on Spintronics
  • Place of Presentation: Tohoku University (Sendai, Japan)
  • Year and Date: 2015-11-18 – 2015-11-20
  • Int'l Joint Research
• [Presentation] Magnetization dynamics in trilayer synthetic antiferromagnets, International Workshop: Spintronics with Antiferromagnets (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: 32nd Reimei Workshop on Frontiers of Condensed Matter Physics
  • Place of Presentation: Tohoku University (Sendai, Japan)
  • Year and Date: 2015-11-16 – 2015-11-17
  • Int'l Joint Research
• [Presentation] Fluid motion induced by spin injection (2015)
  • Author(s): S. Takahashi
  • Organizer: International Workshop on Flow Dynamics and Spintronics
  • Place of Presentation: KTH Royal Institute of Technology (Sockholm, Sweden)
  • Year and Date: 2015-11-12 – 2015-11-13
  • Int'l Joint Research / Invited
• [Presentation] Enhancement of Gilbert damping in trilayer synthetic antiferromagnets via dynamic exchange interactions (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: International conference on solid state devices and materials
  • Place of Presentation: Sapporo Convention Center (Sapporo, Japan)
  • Year and Date: 2015-09-27 – 2015-09-30
  • Int'l Joint Research
• [Presentation] スピン流が人工反強磁性体に及ぼす影響の研究 III (2015)
  • Author(s): 田中健勝, 森山貴広, 永田真己, 水野隼翔, 関剛斎, 高梨弘毅, 千葉貴裕, 高橋三郎, Gerrit E. W. Bauer, 小野輝男
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 関西大学（大阪府吹田市山手町）
  • Year and Date: 2015-09-16 – 2015-09-19
• [Presentation] 絶縁性FeCo-MgFナノグラニュラー膜のTMD効果 (2015)
  • Author(s): 小林伸聖, 岩佐忠義, 石田今朝男, 増本 博, 高橋三郎, 前川禎通
  • Organizer: 第39回 日本磁気学会学術講演会
  • Place of Presentation: 名古屋大学（愛知県名古屋市千種区不老町）
  • Year and Date: 2015-09-08 – 2015-09-11
• [Presentation] スピン流が人工反強磁性体に及ぼす影響の研究 (2015)
  • Author(s): 田中健勝, 森山貴広, 永田真己, 水野隼翔, 関剛斎, 高梨弘毅, 千葉貴裕, 高橋三郎, Gerrit E. W. Bauer, 小野輝男
  • Organizer: 第39回 日本磁気学会学術講演会
  • Place of Presentation: 名古屋大学（愛知県名古屋市千種区不老町）
  • Year and Date: 2015-09-08 – 2015-09-11
• [Presentation] Theory of Current-Induced Spin Torque Resonance of Magnetic Insulators (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: 20th International Conference on Magnetism (ICM)
  • Place of Presentation: Barcelona, Spain
  • Year and Date: 2015-07-05 – 2015-07-10
  • Int'l Joint Research
• [Presentation] Magnetization damping in antiferromagnetically coupled spin valves (2015)
  • Author(s): T. Chiba, G. E. W. Bauer, and S. Takahashi
  • Organizer: New Perspectives in Spintronic and Mesoscopic Physics
  • Place of Presentation: Kashiwa-no-ha Conference Center (Kashiwa, Japan)
  • Year and Date: 2015-06-01 – 2015-06-20
  • Int'l Joint Research
• [Book] Handbook in Spintronics (2015)
  • Author(s): S. Takahashi
  • Total Pages: 36
  • Publisher: Springer