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2007 Fiscal Year Final Research Report Summary

強磁場と人工構造による低次元有機導体の電子物性制御

Research Project

Project/Area Number 15073206
Research Category

Grant-in-Aid for Scientific Research on Priority Areas

Allocation TypeSingle-year Grants
Review Section Science and Engineering
Research InstitutionThe University of Tokyo

Principal Investigator

長田 俊人  The University of Tokyo, 物性研究所, 准教授 (00192526)

Co-Investigator(Kenkyū-buntansha) 大道 英二  神戸大学, 大学院・理学研究科, 准教授 (00323634)
Project Period (FY) 2003 – 2007
Keywords有機導体 / 低次元電子系 / 強磁場 / 半導体超格子 / 角度依存磁気抵抗振動 / Dirac電子系 / 層間コヒーレンス / 磁気貫通系
Research Abstract

本研究の目的は、強磁場・強電場といった極限環境や人工構造を用いて、有機導体の低次元電子系が示す新たな電子物性を探索・解明することである。本研究では、磁場中電荷密度波と層状伝導体の層間磁気伝導という2つの電子物性の問題を扱った。磁場中電荷密度波については、電荷密度波転移温度が低くエネルギー利得が軌道量子化エネルギーやZeemanエネルギーと競合する場合に発現する複雑な逐次相転移や臨界点の問題を扱った。有機導体α-(BEDT-TTF)_2KHg(SCN)_4に関する40T級パルス強磁場実験による相図決定と、磁場誘起スピン密度波転移の標準模型にZeeman効果を加えて拡張した平均場理論で現象を解明した。層状伝導体の磁場中層間伝導については、特に磁場方位依存性の問題を扱った。まず従来の半古典的Fermi面描像を超えて、磁場中層間伝導機構に関するトンネル描像を確立した。これは層間伝導を層間結合強度をパラメータとして摂動展開する方法で、dirty系(incoherent系)からclean系(coherent系)まで系統的かつ量子論的に扱うことが出来る。有機導体を模した各種のGaAs/AlGaAs系半導体多層構造を作製して層間結合を人工的に制御した実験を行うことにより、トンネル描像が予測する種々の角度依存磁気抵抗現象の層間コヒーレンス依存性を確認しその正当性を実証した。また半古典論が無効な量子系である磁気貫通系における磁気抵抗角度効果の振舞いをトンネル描像を用いて理論的に考察し、電荷密度波ギャップによる磁気貫通系である有機導体α-(BEDT-TTF)_2KHg(SCN)_4に関する2軸回転実験でそれらを実証した。さらに多層Dirac電子系における負の層間磁気抵抗をトンネル描像により予測し、負性磁気抵抗が報告されていた有機導体α-(BEDT-TTF)_2 I_3におけるDirac電子系の存在を根拠づけた。

  • Research Products

    (20 results)

All 2008 2007 2006 2005 2004 2003 Other

All Journal Article (14 results) (of which Peer Reviewed: 12 results) Presentation (5 results) Remarks (1 results)

  • [Journal Article] Negative Interlayer Magnetoresistance and Zero-Mode Landau Level in Multilayer Dirac Electron Systems2008

    • Author(s)
      T. Osada
    • Journal Title

      Journal of Physical Society of Japan 77

      Pages: 084711

    • Peer Reviewed
  • [Journal Article] Interlayer Magnetoresistance of Quasi-One-Dimensional Layered Organic Conductors.2007

    • Author(s)
      W. Kang
    • Journal Title

      Physical Review Letters 99

      Pages: 017002

    • Peer Reviewed
  • [Journal Article] Interlayer Surface Transport in Multilayer Quantum Hall Systems under Tilted Magnetic Fields2007

    • Author(s)
      S. Okui
    • Journal Title

      International Journal of Modern Physics B 21

      Pages: 1524-1528

    • Peer Reviewed
  • [Journal Article] 層状低次元導体における磁気抵抗角度効果(II)-高電場下の層間磁気伝導-2007

    • Author(s)
      長田俊人
    • Journal Title

      固体物理 42

      Pages: 157-167

  • [Journal Article] Electric-Field Effect on the Angle-Dependent Magnetotransport Properties of Quasi-One-Dimensional Conductors2006

    • Author(s)
      K. Kobayashi
    • Journal Title

      Physical Review Letters 96

      Pages: 126601

    • Peer Reviewed
  • [Journal Article] Magnetotransport and Magnetic-Field-Induced Density Waves in Low-Dimensional Layered Conductors2006

    • Author(s)
      T. Osada
    • Journal Title

      Journal of Physical Society of Japan 75

      Pages: 051006

    • Peer Reviewed
  • [Journal Article] 層状低次元導体における磁気抵抗角度効果(I)-トンネル描像と層間コヒーレンス-2006

    • Author(s)
      長田俊人
    • Journal Title

      固体物理 41

      Pages: 239-249

  • [Journal Article] Magnetotransport Studies under Megagauss Magnetic Fields2005

    • Author(s)
      T. Osada
    • Journal Title

      Proc. 10th Int. Conf. Megagauss Magnetic Field Generation and Related Topics, Berlin 2004

      Pages: 227-233

    • Peer Reviewed
  • [Journal Article] Electric-Field Effect on the Angle-Dependent Magnetotransport Properties of Quasi-One-Dimensional Conductors2005

    • Author(s)
      K. Kobayashi
    • Journal Title

      Synthetic Metals 155

      Pages: 670-673

    • Peer Reviewed
  • [Journal Article] Electric Field Effect on Vertical Magnetotransport in Multilayer Systems under Tilted Magnetic Fields2004

    • Author(s)
      K. Kobayashi
    • Journal Title

      Physica E 22

      Pages: 385-388

    • Peer Reviewed
  • [Journal Article] Tunneling Picture of Interlayer Magnetotransport in Multilayer Systems2003

    • Author(s)
      T. Osada
    • Journal Title

      Physica B 18

      Pages: 200-201

    • Peer Reviewed
  • [Journal Article] Interlayer Coherency and Angular Dependent Magnetoresistance Oscillations in Quasi-Two-Dimensional Conductors2003

    • Author(s)
      M. Kuraguchi
    • Journal Title

      Synthetic Metals 133-134

      Pages: 113-115

    • Peer Reviewed
  • [Journal Article] General Quantum Picture for Magnetoresistance Angular Effects in Quasi-One-Dimensional Conductors2003

    • Author(s)
      T. Osada
    • Journal Title

      Synthetic Metals 133-134

      Pages: 75-77

    • Peer Reviewed
  • [Journal Article] Influence of Interlayer and Interchain Coherence on MagnetoresistanceAngular Effects in Q1D Conductors2003

    • Author(s)
      T. Osada
    • Journal Title

      Synthetic Metals 135-136

      Pages: 653-654

    • Peer Reviewed
  • [Presentation] Successive Phase Transitions in Charge Density Wave State under High Magnetic Fields2005

    • Author(s)
      T. Osada
    • Organizer
      International Symposium on Crystalline Organic Metals, Superconductors, and Ferromagnets (ISCOM2005)
    • Place of Presentation
      Key West, USA.
    • Year and Date
      20050911-20050916
  • [Presentation] Successive Transitions in Charge Density Wave State under High Magnetic Fields2005

    • Author(s)
      T. Osada
    • Organizer
      International Symposium on Molecular Conductors (ISMC2005)
    • Place of Presentation
      Hayama, Japan
    • Year and Date
      20050717-20050721
  • [Presentation] Ultra-High Magnetic Field Transport Measurements of Low-Dimensional Conductors2004

    • Author(s)
      T. Osada
    • Organizer
      International Conference on Application of HighMagnetic Fields in Semiconductor Physics (SemiMag16)
    • Place of Presentation
      Tallahassee, USA
    • Year and Date
      20040802-20040806
  • [Presentation] Transport Study of Low- Dimensional Conductors under Ultra-High Magnetic Fields2004

    • Author(s)
      T. Osada
    • Organizer
      International Conference on Science and Technology of Synthetic Metals (ICSM2004)
    • Place of Presentation
      Woolongong, Australia
    • Year and Date
      20040628-20040702
  • [Presentation] Ultra-High Magnetic Field Transport in Low-Dimensional Conductors2003

    • Author(s)
      T. Osada
    • Organizer
      International Symposium on Crystalline OrganicMetals, Superconductors, and Ferromagnets (ISCOM2003)
    • Place of Presentation
      Port-Bourgenay, France
    • Year and Date
      20030922-20030926
  • [Remarks]

    • URL

      http://osada.issp.u-tokyo.ac.jp/

URL: 

Published: 2010-06-09   Modified: 2016-04-21  

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