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2011 Fiscal Year Annual Research Report

コヒーレント位相スピントランスファーマイクロ波発振磁性体の開発

Research Project

Project/Area Number 21246049
Research InstitutionTohoku University

Principal Investigator

佐橋 政司  東北大学, 大学院・工学研究科, 教授 (20361123)

Co-Investigator(Kenkyū-buntansha) 土井 正晶  東北学院大学, 工学部, 教授 (10237167)
三宅 耕作  東北大学, 大学院・工学研究科, 助教 (20374960)
Keywordsナノ接点 / 強磁性体 / スピンバルブ構造 / 狭窄磁壁 / スピントランスファー / マイクロ波発振 / スピントロニクス / 自己組織化
Research Abstract

本研究課題の主要研究題目である「自己組織化プロセスにより作製される強磁性ナノ接点スピンバルブ磁性体」の磁気抵抗特性,直流電流駆動マイクロ波発振特性,およびそれらの相関について,スピンバルブ構造,磁界,電流等を制御変数とした実験研究を行い,研究協力者(今村裕志)の接点磁気構造および発振についての理論・シミュレーション結果と照らし合わせることで,コヒーレント位相高出力発振を得るための磁性体開発の主導原理となる以下の物理的指針を得ることが出来た。
1.強磁性ナノ接点スピンバルブ磁陸体の磁気抵抗原理は,接点に狭窄された磁壁によるスピン依存散乱(Levy&Zhangのミストラッキング理論)とスピン蓄積で説明可能.
2.高磁気抵抗比を得るためには,ナノ接点を構成する強磁性体の電子伝導におけるスピン分極率(β)を高めることが何より重要である.
3.ナノ接点への酸素等の不純物の混入がβを下げ,結果として磁気抵抗比を下げることを実験より明らかにした.高磁気抵抗比,高出力発振を得るためには,ナノ接点の純度の向上(比抵抗ρの低減)が不可欠.
4.発振原理は,接点に狭窄された磁壁のスピントランスファー振動を駆動源とする複数の接点間のフリー層(スピン波)を介したコヒーレント位相共鳴.
5.複数の強磁性ナノ接点を含むスピンバルブ磁性体では,接点部において高電流密度化が実現され,5~10MHzの狭線幅発振が可能.強磁性ナノ接点スピンバルブ磁性体の優位性を確認.
6.厚いフリー層は磁気渦構造となり,発振周波数~1GHz,実効値にして0.2μWの高出力発振が得られ,かつ5MHzの狭線幅となる.また,強磁性ナノ接点スピンバルブ磁性体では,残留磁化状態;すなわち零磁場を挟んだ極めて低磁場(±400e)で磁気渦構造となり,μW級の高出力発振が得られることを明らかにした.
7.磁気渦構造の発振もSlavinのAuto-Oscillationモデルで定量的に説明可能であることを明らかにした.高出力化,高発振エネルギー化には,高磁気抵抗比に加え,低閾値電流が有効.

  • Research Products

    (18 results)

All 2012 2011 Other

All Journal Article (11 results) (of which Peer Reviewed: 11 results) Presentation (6 results) Remarks (1 results)

  • [Journal Article] Enhancement of Interfacial Specific Resistance by the Insertion of Fe(001) Layers Between Alternate Monatomic [Fe/Co]n Superlattices and Ag Spacer2012

    • Author(s)
      J.W.Jung, Y.Shiokawa, Z.Jin, M.Doi, M.Sahashi
    • Journal Title

      Journal of Applied Physics

      Volume: 111 Pages: 07B707-1-07B7071-3

    • DOI

      Doi:10.1063/1.3677681

    • Peer Reviewed
  • [Journal Article] Grain Growth of Cr2O3 Thin Film Layer on Exchange Coupling of Cr2O3/Co Interface2012

    • Author(s)
      T.Nozaki, N.Shimomura, T.Ashida, Y.Sato, M.Sahashi
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: (未定)(accepted)

    • Peer Reviewed
  • [Journal Article] Study on High-Frequency 3-D Magnetization Precession Modes of Circular Magnetic Nano-Dots Using Coplanar Wave Guide Vector Network Analyzer Ferromagnetic Resonance2012

    • Author(s)
      Kousaku Miyake, Seung-Mo Noh, Tomoaki Kaneko, Hiroshi Imamura, M.Sahashi
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: 48(to be published)

    • Peer Reviewed
  • [Journal Article] Spin Dynamics in Ferromagnetic Resonance for Nano-Sized Magnetic Dot Arrays : Metrology and Insight Into Magnetization Dynamics2011

    • Author(s)
      Noh S, Monma D, Miyake K, Doi M, Kaneko T, Imamura H, Sahashi M
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: 47 Pages: 2387-2390

    • DOI

      DOI:10.1109・TMAG.2011.2150741

    • Peer Reviewed
  • [Journal Article] Influence of the Stress Current on Spin-Torque-Oscillator With NCMRSV Devices2011

    • Author(s)
      Nakamura T, Doi M, Hashimoto S, Iwasaki H, Sahashi M
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: 47 Pages: 3377-3379

    • DOI

      DOI:10.1109/TMAG.2011.2157107

    • Peer Reviewed
  • [Journal Article] Frequency Modulation of a Nano-Oxide Layer-Based Spin-Torque Oscillator With FeCo Nanocontacts2011

    • Author(s)
      Al-Mahdawi M, Doi M, Hashimoto S, Fuke NH, Iwasaki H, Sahashi M
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: 47 Pages: 3380-3382

    • DOI

      DOI:10.1109・TMAG.2011.2159104

    • Peer Reviewed
  • [Journal Article] Oxidation and Annealing Process : Morphological Change and Nanocontact MR in Spin Valves With FeCo-AlO(x) NOL Spacer2011

    • Author(s)
      Shiokawa Y, Shiota M, Watanabe Y, Otsuka T, Doi M, Sahashi M
    • Journal Title

      IEEE TRANSACTIONS ON MAGNETICS

      Volume: 47 Pages: 3470-3473

    • DOI

      DOI:10.1109・TMAG.2011.2157110

    • Peer Reviewed
  • [Journal Article] Enhancement of microwave oscillation under angled in-plane magnetic field in ferromagnetic nano-contact spin-valves2011

    • Author(s)
      Suzuki H, Nakamura T, Endo H, Doi M, Tsukahara H, Imamura H, Fuke NH, Hashimoto S, Iwasaki H, Sahashi M
    • Journal Title

      Applied Physics Letters

      Volume: 99 Pages: 092507

    • DOI

      DOI:10.1063/1.3619835

    • Peer Reviewed
  • [Journal Article] Spin scattering asymmetric coefficients and enhanced specific interfacial resistance of fully epitaxial current-perpendicular-to-plane giant magnetoresistance spin valves using alternate monatomic layered [Fe/Co](n) and a Ag spacer layer2011

    • Author(s)
      Jung JW, Shiozaki R, Doi M, Sahashi M
    • Journal Title

      JOURNAL OF APPLIED PHYSICS

      Volume: 109 Pages: 07C510

    • DOI

      DOI:10.1063/1.3556925

    • Peer Reviewed
  • [Journal Article] Spin-transfer torque driven ferromagnetic resonance in nano-contact magnetoresistive devices and its characteristics2011

    • Author(s)
      Okutomi Y, Miyake K, Doi, M, Fuke HN, Iwasaki H, Sahashi M
    • Journal Title

      JOURNAL OF APPLIED PHYSICS

      Volume: 109 Pages: 07C727

    • DOI

      DOI:10.1063/1.3562511

    • Peer Reviewed
  • [Journal Article] Spin-transfer-induced microwave oscillations in spin valves with ferromagnetic nano-contacts in oxide spacer layer2011

    • Author(s)
      Doi M, Endo H, Shirafuji K, Kawasaki S, Sahashi M, Fuke HN, Iwasaki H, Imamura H
    • Journal Title

      JOURNAL OF PHYSICS D-APPLIED PHYSICS

      Volume: 44 Pages: 092001

    • DOI

      DOI:10.1088/0022-3727/44/9/092001

    • Peer Reviewed
  • [Presentation] Enhancement of microwave oscillations in ferromagnetic nano-contact magnetoresistive spin valves2011

    • Author(s)
      Masashi Sahashi, Yoshihito Okutomi, Hiroaki Suzuki, Kousaku Miyake
    • Organizer
      Spin Mater Voice workshop
    • Place of Presentation
      Versailles (France)
    • Year and Date
      20111214-20111216
  • [Presentation] Magnetic nanocontact MR with high MR ratio and low RA2011

    • Author(s)
      H.Iwasaki, S.Hashimoto, N.H.Fuke, M.Takagishi, M.Sahashi
    • Organizer
      56^<th> ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS
    • Place of Presentation
      Scottsdale, AZ, USA
    • Year and Date
      20111030-20111103
  • [Presentation] Influence of Cr2O3-AFM layer deposition conditions for the AFM/FM interfaces2011

    • Author(s)
      T.Ashida, N.Shimomura, M.Belmoubarik, T.Nozaki, M.Sahashi
    • Organizer
      56^<th> ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS
    • Place of Presentation
      Scottsdale, AZ, USA
    • Year and Date
      20111030-20111103
  • [Presentation] Spin-transfer induced large power coherent microwave generation in NCMR devices at a multi-domain state2011

    • Author(s)
      Y.Okutomi, Y.Kozono, K.Miyake, S.Hashimoto, H.Iwasaki, M.Sahashi
    • Organizer
      56^<th> ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS
    • Place of Presentation
      Scottsdale, AZ, USA
    • Year and Date
      20111030-20111103
  • [Presentation] Self-Organized Nano-Oxide-Layer with Magnetic Nano-Contacts and Its Applications to Microwave/Magnetoelectric Devices2011

    • Author(s)
      Masashi Sahashi
    • Organizer
      BIT'S 1^<st> Annual World Congress of Nano-S&T
    • Place of Presentation
      Dalian, China(Invited)
    • Year and Date
      20111023-20111026
  • [Presentation] STUDY ON HIGH FREQUENCY 3D MAGNETIZATION DYNAMICS OF MAMR-FGL WITH CIRCULAR MAGNETIC NANO-DOTS USING CPW-NAFMR2011

    • Author(s)
      Masashi SAHASHI, Seung MoNOH, Kousaku MIYAKE, Tomoaki KANEKO, Hiroshi IMAMURA
    • Organizer
      THE MAGNET INTERNATIONAL CONFERENCE ON MAGNETIC RECORDING HEADS AND SYSTEMS
    • Place of Presentation
      Minneapolis, Minnesota, USA(Invited)
    • Year and Date
      20110829-20110831
  • [Remarks]

    • URL

      http://www.ecei.tohoku.ac.jp/sahashi/naiyou.html

URL: 

Published: 2013-06-26  

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