• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

強相関電子系におけるスピン・軌道の量子臨界揺らぎ

Research Project

Project/Area Number 16684012
Research Category

Grant-in-Aid for Young Scientists (A)

Allocation TypeSingle-year Grants
Research Field Condensed matter physics II
Research InstitutionKyoto University

Principal Investigator

中辻 知  京都大学, 大学院・理学研究科, 講師 (70362431)

Project Period (FY) 2004 – 2005
Project Status Completed (Fiscal Year 2005)
Budget Amount *help
¥28,860,000 (Direct Cost: ¥22,200,000、Indirect Cost: ¥6,660,000)
Fiscal Year 2005: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2004: ¥22,490,000 (Direct Cost: ¥17,300,000、Indirect Cost: ¥5,190,000)
Keywords量子臨界点 / スピン液体 / モット転移 / メタ磁性転移 / 幾何学的フラストレー / モット絶縁体 / 軌道秩序 / パイクロア酸化物 / ホッピング伝導
Research Abstract

低スピン系(S=1)で初めて、低温まで正確に3角格子の対称性を保つ、擬2次元系NiGa2S4を発見した。まず、高純度多結晶の育成法を確立した。この多結晶体を用いた磁気・熱測定により、80Kの磁気相間を持つにもかかわらず、0.35Kまで磁気秩序が抑えられたこと、また、10K以下で非従来型のスピン状態が実現していることを見出した。また、中性子実験により、スピンの持つ短距離相間の構造を明らかにした。比熱は低温で温度2乗則を示し、低温でのコヒーレンス長は200nmものマクロな距離になり、新しい量子臨界的状態を形成している可能性がある。
局在スピンを持つパイロクロア型酸化物磁性体は、数多く知られているが、これまで報告されていたものすべてが比較的高い温度で磁気転移を示す。特に金属でありながら局在スピンが低温まで秩序を示さないというものは皆無であった。我々は、Pr2Ir2O7がその初めての例であり、低温で量子臨界的スピン液体的に振る舞うことを、最近育成に成功した単結晶での研究により見出した。さらに、RKKY相互作用による磁気秩序が幾何学的フラストレーションにより押さえられたことで、酸化物で初めての近藤効果が見られた。
Ca2-xSrxRuO4は軌道の秩序により、様々な基底状態をとる多重バンド型モット転移系である。モット転移近傍の重い電子状態での量子メタ磁性転移近傍での電子構造の変化を、電気抵抗・ホール係数の精密測定からプローブし、角度依存型磁気抵抗効果等の興味深い量子伝導現象を見出した。重い電子フェルミ液体のフェルミ面の形状を反映したc軸方向の磁気抵抗の面内方位依存性が、低磁場の2回対称から擬4回対称へと変化する。一次元的バンド(dyz,zx)が支配的な反強磁性状態から2次元的なバンド(dxy)による強磁性に、数テスラの磁場によりスイッチングが起こったと考えられる。

Report

(2 results)
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • Research Products

    (24 results)

All 2006 2005 2004

All Journal Article (24 results)

  • [Journal Article] Metallic Spin-Liquid Behavior of the Geometrically Frustrated Kondo Lattice Pr2Ir2O72006

    • Author(s)
      S.Nakatsuji et al.
    • Journal Title

      Physical Review Letters 96

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Orbital-Selective Mass Enhancements in Multiband Ca2-xSrxRuO4 Systems Analyzed by the Extended Drude Model2006

    • Author(s)
      J.S.Lee et al.
    • Journal Title

      Physical Review Letters 96

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Structural Aspects of Metamagnetism in Ca2-xSrxRuO4:Evidence for Field Tuning of Orbital Occupation2005

    • Author(s)
      M.Kriener et al.
    • Journal Title

      Physical Review Letters 95

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Quantitative Analysis of Sr2RuO4 Angle-Resolved Photoemission Spectra : Many-Body Interactions in a Model Fermi Liquid2005

    • Author(s)
      N.Ingle et al.
    • Journal Title

      Physical Review B 72

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Severe Fermi Surface Reconstruction at a Metamagnetic Transition_in_Ca2-xSrxRuO4 (for 0.2 <= x = 0.5)2005

    • Author(s)
      L.Balicas et al.
    • Journal Title

      Physical Review Letters 95

    • Related Report
      2005 Annual Research Report
  • [Journal Article] A Comparison of the Structure and Localized Magnetism in Ce2PdGa12 with the Heavy Fermion CePdGa62005

    • Author(s)
      R.T.Macaluso et al.
    • Journal Title

      Journal of Solid State Chemistry 178

      Pages: 3547-3553

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Spin Disorder on a Triangular Lattice2005

    • Author(s)
      S.Nakatsuji et al.
    • Journal Title

      Science 309

      Pages: 1697-1700

    • Related Report
      2005 Annual Research Report
  • [Journal Article] High Pressure Diffraction Studies on Ca2RuO42005

    • Author(s)
      P.Steffens et al.
    • Journal Title

      Physical Review B 72

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Orbital Ordering Transition in Ca2RuO4 Observed with Resonant X-ray Diffraction2005

    • Author(s)
      I.Zegkinoglou et al.
    • Journal Title

      Physical Review Letters 95

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Crystalline Electric Field Levels and Magnetic Properties of the Metallic Pyrochlore Compound Pr2Ir2O72005

    • Author(s)
      Y.Machida et al.
    • Journal Title

      Journal of the Physics and Chemistry of Solids 66

      Pages: 1435-1437

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Electronic Structure and Evolution of the Orbital State in Metallic Ca2-xSrxRuO42005

    • Author(s)
      H.J.Noh et al.
    • Journal Title

      Physical Review B 72

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Magnetic Field-Tuned Quantum Critical Point in CeAuSb22005

    • Author(s)
      L.Balicas et al.
    • Journal Title

      Physical Review B 72

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Unpaired Electrons in the Heavy-Fermion Superconductor CeCoIn52005

    • Author(s)
      M.Tanatar et al.
    • Journal Title

      Physical Review Letters 95

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Ferro-Type Orbital State in the Mott Transition System Ca2-xSrxRuO4 Studied by the Resonant X-Ray Scattering Interference Technique2005

    • Author(s)
      M.Kubota et al.
    • Journal Title

      Physical Review Letters 95

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Lattice Dynamics and the Electron-Phonon Interaction in Ca2RuO42005

    • Author(s)
      H.Rho et al.
    • Journal Title

      Physical Review B 71

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Gradual Transition from Insulator to Semimetal of Ca1-xEuxB6 with Increasing Eu Concentration2005

    • Author(s)
      R.Urbano et al.
    • Journal Title

      Physical Review B 71

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Raman Scattering Studies of Ca2-xSrxRuO42005

    • Author(s)
      H.Rho et al.
    • Journal Title

      Physica B-Condensed Matter 359

      Pages: 1270-1272

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Magnetotransport in NdB6 Single Crystal2005

    • Author(s)
      J.Stankiewicz et al.
    • Journal Title

      Physical Review B 71

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Mechanism of hopping transport in disordered Mott insulators2004

    • Author(s)
      S.Nakatsuji et al.
    • Journal Title

      Physical Review Letters 93

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Strongly Enhanced Magnetic Fluctuations in a Large-Mass Layered Ruthenate2004

    • Author(s)
      O.Friedt et al.
    • Journal Title

      Physical Review Letters 93

    • Related Report
      2004 Annual Research Report
  • [Journal Article] New Compounds Based on Pyrochlore Structure : R_2Nb_2O_7(R=Dy, Yb)2004

    • Author(s)
      O.Sakai et al.
    • Journal Title

      Journal of the Physical Society of Japan 73

      Pages: 2829-2833

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Correlation effects in Sr2RuO4 and Ca2RuO4:Valence-band photoemission spectra and self-energy calculations2004

    • Author(s)
      T.T.Tran et al.
    • Journal Title

      Physical Review B 70

      Pages: 153106-153106

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Bond-length dependence of charge-transfer excitations and stretch phonon modes in perovskite ruthenates : Evidence of strong p-d hybridization effects2004

    • Author(s)
      J.S.Lee et al.
    • Journal Title

      Physical Review B 70

      Pages: 85103-85103

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Orbital state and metal-insulator transition in Ca_<2-x>Sr_xRuO_4(x=0.0 and 0.09) studied by x-ray absorption spectroscopy2004

    • Author(s)
      T.Mizokawa et al.
    • Journal Title

      Physical Review B 69

    • Related Report
      2004 Annual Research Report

URL: 

Published: 2004-04-01   Modified: 2020-05-15  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi