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Theoretical study on magnetism and superconductivity in almost lo-calized strongly correlated elecron systems

Research Project

Project/Area Number 08640434
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体物性Ⅱ(磁性・金属・低温)
Research InstitutionHOKKAIDO UNIVERSITY

Principal Investigator

OHKAWA Fusayoshi  Grad.School of Science, Hokkaido Univ., Prof., 大学院・理学研究科, 教授 (00107442)

Project Period (FY) 1996 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥1,400,000 (Direct Cost: ¥1,400,000)
KeywordsKondo effect / local quantum spin fluctuations / 1 / d expansion / local-moment magnetism / itinerant-electron magnetism / high-temperature superconducticity / Curie-Weiss law / metamagnetism / 強相関電子系 / 磁性 / 超伝導 / スピン揺動 / 強相関電子
Research Abstract

One of the most important issues for magnetism is to construct a unified theory that is applicable to both local-moment magnetism and itinerant electron magnetism. The 1/d expansion methof has been developed, with d being the spatial dimensionality. This is apllicable to both local-moment magnetism and itinerant electron magnetism. Local quantuam spin fluctuations can be correctly considered in the best single-site approximation (SSA). The SSA is equivalent to solving a mapped Anderson model to be self-consistently determined form a maaping condition. This means that the Kondo effect plays a significant and essential role in not only dilute magnetic alloys but also periodical strongly correlated electron systems. Intersite effects can be perturbatively treated starting from the SSA.
Various issues have been studied by the 1/d expansion method. (1) The corssover of magnetic structures between sinusoidal and helical stuructures has been studied. (2) There is another mechanism of the Curie-Weiss law for itinerant electron magnetism besides the mode-mode coupling mechanism, which is of higher in 1/d : the temperature dependence of the magnetic mean field, which is of leading order in l/d. (3) A mechanism of high-temperature superconductivity in cuprate-oxide superconductors has been proposed ; the formation of dx_<x2-y2> wave Cooper pairs between heavy quasiparticles in the vicinity, of the Mott transtion. The main pairing interaction is the superexchange interaction between nearest neighbors. (4) A new type of magnetic exchange interaction has been studied. It is caused by the virtual exchange of pair excitatiolns of quasiparticles in spin channels, has been studied. The strength of this exchange interaction is about the bandwidth of quisipartgicles. (5) It has been proposed that a metamagnetic transition in CeRu_2Si_2 is mainly caused by this exchange interaction.

Report

(4 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report
  • 1996 Annual Research Report
  • Research Products

    (23 results)

All Other

All Publications (23 results)

  • [Publications] 大川房義: "Relevance and irrelevance of three effective Hamiltonians for high-temperature superconductors" Physical Review B. 59巻13号 印刷中. (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 佐藤寛之: "Field-induced ferromagnetic exchange interactions in metamagnetic transitions of heavy-electron liquids" Physical Review B. 57巻3号. 5891-5899 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 大川房義: "Sinuosidal and Helical Structures in Itinerant-Electron Magnets" Journal of Physical Society of Japan. 67巻2号. 535-542 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 大川房義: "Magnetic Exchange Interactions between Quasiparticles in Itienrant-Electron Magnets" Journal of Physical Society of Japan. 67巻2. 525-534 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 大川房義: "Quantum and thermal spin fluctuations in itinerant-electron magnets" Physical Review B. 57巻1号. 412-425 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 大川房義: "Heavy quasiparticles and Cooper-pair interaction in the Hubbard model" Physical Review B. 54巻23号. 15388-15410 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.J.Ohkawa: "Relevance and irrelevance of three effective Hamiltonians for high-temperature superconductors" Physical Review B. 59, No.13 (in press). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] H.Satoh and F.J.Ohkawa: "Field-induced ferromagnetic exchange interactions in meta-magnetic transitions of heavy-electron liquids" Physical Review B. 57, No.3. 5891-5899 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.J.Ohkawa, K.Onoue and H.Satoh: "Sinusoidal and Helical Structures in Itinerant-Electron Magnets" Journal of Physical Society of Japan. 67, No.2. 535-542 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.J.Ohkawa: "Magnetic Exchange Interactions between Quasiparticles in Itienrant-Electron Magnets" Journal of Physical Society of Japan. 67, No.2. 525-534 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.J.Ohkawa: "Quantum and thermal spin fluctuations in itinerant-electron magnets" Physical Review B. 57, No.1. 412-425 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] F.J.Ohkawa: "Heavy quasiparticles and Cooper-pair interaction in the Hubbard model" Physical Review B. 54, No.23. 15388-15410 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 大川房義: "Relevance and irrelevance of three effective Hamiltonians for high-temperature superconductors" Physical Review B. 59巻13号. (1999)

    • Related Report
      1998 Annual Research Report
  • [Publications] 佐藤寛之: "Field-induced ferromagnetic exchange interactions in metamagnetic transitions of heavy-electron liquids" Physical Review B. 57巻3号. 5891-5899 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 大川房義: "Sinusoidal and Helical Structures in Itinerant-Electron Magnets" Journal of Physical Society of Japan. 67巻2号. 535-542 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 大川房義: "Magnetic Exchange Interactions between Quasiparticles in Itienrant-Electron Mgnets" Journal of Physical Society of Japan. 67巻2号. 525-534 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 大川房義: "Quantum and thermal spin fluctuations in itinerant-electron magnets" Physical Review B. 57巻1号. 412-425 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 大川房義: "Heavy quasiparticles and Cooper-pair interaction in the Hubbard model" Physical Review B. 54巻23号. 15388-15410 (1996)

    • Related Report
      1998 Annual Research Report
  • [Publications] 大川房義: "Quantum and thermal spin fluctuations in itinerant-electron magrets" Physical Review B. 57巻1号. 412-415 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] 大川房義: "Mugnetic Exchange Interactions between Quasiparticles in Itinerant-electron magnets" Journal of the Physical Soceity of Japan. 67巻2号. 525-534 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] 大川房義: "Sinusoidal and Helical Structures in Itinerant-Electron Magnets" Journal of the Physical Society of Japan. 67巻2号. 535-542 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] 佐藤寛之: "Field-induced ferromagnetic Exchange Interactious in metamagnetic transitions of heavy-electron liquids" Physical Review B. 57巻3号. (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] Fusayoshi J. Ohkawa: "Heavy quasiparticles and Cooper-pair interaction in the Hubbard model" Physical Review-B. 54巻23号. 15388-15410 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2020-05-15  

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