1991 Fiscal Year Final Research Report Summary
Theoretical Study of Superconductivity and Strongly Correlated Fermions
| Project/Area Number |
01540296
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | Nagoya University |
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Principal Investigator |
YAMADA Kazuo Nagoya Univ., College of General Education, Prof., 教養部, 教授 (10022542)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAKE Kazumasa Osaka Univ., Faculty of Engineering Science, Assoc. Prof., 基礎工学部, 助教授 (90109265)
HIRASHIMA Dai Nagoya Univ., School of Science, Assist. Prof., 理学部, 助手 (20208820)
MATSUURA Tamifusa Nagoya Univ., School of Science, Assoc. Prof., 理学部, 助教授 (10022609)
KASHIWAMURA Shohei Nagoya Univ., College of General Education, Prof., 教養部, 教授 (80023563)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Heavy Electrons / Cuprate Superconductors / Strongly Correlated Electrons / Fermi Liquid Theory / Hubbard Model / t-J Model / d-p Model / Cooper Pairing vs Bose Condensation |
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| Research Abstract |
Main purpose of this research project has been to clarify the origin of anomalous behaviors of normal state of strongly correlated fermion systems and the mechanism of their superconductivity. The following progress has been achieved. (1)On the basis of "duality theory", which incorporates explicitly the dual nature of itinerant and localized characters common to strongly correlated electrons, both tlie systematics of metamagnetism and tlie origin of extremely weak antiferromagnetism of heavy electron systems has been explained qulitatively. It has also been shown on the same formalism that anomalous temperature and "hole"-concentration dependence of cuprates can be elucidated. (2)Nature of d-p model has been investigated systematically by 1/N-expansion technique. In particular, structure of one-electron states has been calculated over the low- and high-energy region, and nature of metal-insulator transition and charge fluctuations has been clarified. (3)On the basis of numerical diagonalization method, it has been clarified how the effect of frustrations is reflected on a realization condition of spin liquid state in quantum Heisenberg spin systems and a possibility of separation of charge- and spin-degrees of freedom in t-J model. (4)The effect of pair fluctuations on two-dimensional superconductor has been studied both by the Nozieres&Schmitt-Rink formalism and the modecoupling formalism, and a certain progress towards comprehensive description of crossover phenomenon between Cooper-pair condensation and Bose condensation of "di-electronic molecules" has been achieved.
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Research Products
(32 results)
