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低次元量子多体系における相関効果の研究

Research Project

Project/Area Number 12046244
Research Category

Grant-in-Aid for Scientific Research on Priority Areas

Allocation TypeSingle-year Grants
Review Section Science and Engineering
Research InstitutionOsaka University

Principal Investigator

川上 則雄  大阪大学, 大学院・工学研究科, 教授 (10169683)

Project Period (FY) 2000 – 2003
Project Status Completed (Fiscal Year 2003)
Budget Amount *help
¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2001: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥3,000,000 (Direct Cost: ¥3,000,000)
Keywords強相関電子系 / 低次元 / フラストレーション / 遷移金属酸化物 / 軌道効果 / 電子相関 / 遷移金属化合物 / 低次元電子系 / 軌道自由度 / 量子ゆらぎ
Research Abstract

還移金属化合物におけるスピン・電荷・軌道自由度に起因する現象を理解するするため、動的平均場近似、厳密対角化法、ゆらぎ交換近似などを用いた研究を展開した。
1.モット絶縁体における軌道縮退効果:遷移金属酸化物のモット転移に対する軌道縮退の効果について動的平均場近似を用いて調べた。軌道選択型モット転移が実現することを示し、ストロンチウム酸化物でこれが生じている可能性を議論した。
2.スピンギャップ相へのホールドープ:スピンギャップをもつ絶縁相である近藤絶縁体と直交ダイマースピン系へのホールドープ効果を調べた。特に量子臨界点近傍でのホールダイナミクスについて詳細な研究を行った。
3.フラストレート格子系における電子相関:カゴメ格子上での電子系のフラストレーションと電子相関の関わり合いを、FLEX近似を用いて調べた。フラストレーションによって準粒子形成が安定化されることを明らかにした。
4.スピンアイス系のフラストレーション効果:フラストレーション格子の典型例であるガーネット格子でのイジング模型をモンテカルロ法で調べ、大きな残留エントロピーを持つスピンアイス的な状態が実現することを明らかにした。また、双極子相互作用によって新奇な磁気秩序が安定化されることを示した。

Report

(4 results)
  • 2003 Annual Research Report
  • 2002 Annual Research Report
  • 2001 Annual Research Report
  • 2000 Annual Research Report

Research Products

(24 results)

All Other

All Publications (24 results)

  • [Publications] Akira Kawaguchi: "Hole-Doping Effects on a Frustrated Spin Ladder"J.Phys.Soc.Jpn.. Vol.72. 405-410 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Akihisa Koga: "Quantum phase transitions of the S=1 Shastry-Sutherland model"J.Phys.Soc.Jpn.. Vol.72. 938-942 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Satoshi Fujimoto: "Drude Weight at Finite Temperatures for Some Non-Integrable Quantum Systems in One Dimension"Phys.Rev.Lett.. Vol.90. 197202/1-197202/4 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Akihisa Koga: "Effects of degenerate orbitals on the Hubbard model"J.Phys.Soc.Jpn.. Vol.72. 1306-1307 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Akira Kawaguchi: "Quasiparticle excitations in the hole-doped Hubbard model with orthogonal-dimer structure"Physica B. Vol.329. 1269-1270 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Yoshiki Imai: "Ground-State Properties of the Modified Periodic Anderson Model in Infinite Dimensions"Acta Physica Polonica B. Vol.34. 779-782 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Akira Kawaguchi: "Magnetization process for a quasi-1D S=1 antiferromagnet"Phys. Rev.. B65. 214405-1-214405-5 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Yoshiki Imai: "Spectral functions in itinerant electron systems with geometrical frustration"Phys. Rev.. B65. 233103-1-233103-4 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Akihisa Koga: "Frustration-Induced Phase Transitions in the Spin-S Orthogonal Dimer Chain"Phys. Rev.. B65. 214415-1-214415-5 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Satoshi Miyashita: "Dynamical Properties of One-Dimensional Multicomponent Quantum Liquids in Metallic Phase"J. Phys. Soc. Jpn.. 71. 1947-1955 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Akihisa Koga: "Stability of a Metallic State in the Two-Orbital Hubbard Model"Phys. Rev.. B65. 165107-1-165107-6 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Akira Kawaguchi: "Orbital Order in a Quasi-One-Dimensional Spin-Orbital Model"J. Phys. Soc. Jpn.. 71. 3096-3097 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] 川上則雄: "一次元電子系の数理"岩波書店. 68 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Akira Kawaguchi: "Magnetic Properties for the One-Dimensional Multicomponent Spin-Gap System"Phys. Rev.. B63. 144413-1-144413-7 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Yoshihiro Takushima: "Competing Spin-Gap Phases in a Frustrated Quantum Spin System"J. Phys. Soc. Jpn.. 70. 1369-1374 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Yoshiki Imai: "Heavy Quasi-Particles in the Two-Orbital Hubbard Model"J. Phys. Soc. Jpn.. 70. 2365-2370 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] 古賀昌久: "クラスター展開を用いた量子スピン系の相転移の理論"固体物理. 36. 533-541 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Yoshiki Imai: "Quasi-Particle Properties in Two-Orbital Correlated Electron Systems"J. Phys. Soc. Jpn. Suppl.. (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] Akihisa Koga: "Quantum phase transitions for the Haldane system in higher dimensions"Phys.Rev.. B61. 6133-6137 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Akihisa Koga: "Phase Diagram for Quantum Spin Systems with Ladder, Plaquette and Mixed-Spin Structures"J.Phys.Soc.Jpn.. 69. 1843-1845 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Yoshihiro Takushima: "Magnetic Double Structure for S=1, 1/2 Mixed Spin Systems"Phys.Rev.. B61. 15189-15195 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Akihisa Koga: "Quantum Phase Transitions in the Shastry-Sutherland Model for SrCu_2(BO_3)_2"Phys.Rev.Lett.. 84. 4461-4464 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Akihisa Koga: "First-order quantum phase transition in the orthogonal-dimer spin chain"Phys.Rev.. B62. 5558-5563 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Yoshiki Imai: "Correlation Effects on the Double Exchange Model in a Ferromagnetic Metallic Phase"J.Phys.Soc.Jpn.. 69. 3063-3067 (2000)

    • Related Report
      2000 Annual Research Report

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Published: 2000-03-31   Modified: 2018-03-28  

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