| Project/Area Number |
15540340
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
YAMADA Kosaku KYOTO UNIVERSITY, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90013515)
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| Co-Investigator(Kenkyū-buntansha) |
IKEDA Hiroaki KYOTO UNIVERSITY, Graduate School of Science, Assistant Professor, 大学院・理学研究科, 助手 (90311737)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | High Tc Superconductors / Correlated Electron Systems / Heavy Fermions / Superconductivity of LSCO / Superconductivity of YBCO / Organic Superconductors / CeCoIn5 / Anisotropic Superconductors / 有効質量 / 重い電子 / Hubbardモデル / d-Pモデル / 電子相関 / 有機超伝導 / YBCO / LSCO / NaxCoO_2 / 強磁性UGe2 / 磁場侵入長 / PuCoGa_5 / CeIn_3 / 摂動理論 / d-波の電子対 / P-波の電子対 |
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| Research Abstract |
This year is the last year for our project. We are completing our research on superconductivity in strongly correlated electron systems. Our theory concludes the following points.
1.Transition temperature of superconductivity is determined by the momentum dependence of electron interaction originating from the Coulomb repulsion U and mass enhancement factor 1/z.
2.We have calculated up to the fourth order terms of self-energy terms. The fourth order terms play essential roles in giving actual mass enhancement factor.
3.By using the forth order perturbation theory we can derive the Dyson-Gorkov Equation. By solving this equation we can discuss the roles of renormalization factor and anisotropic interaction between quasi-particles.
4.We can explain the reason why Tc in LSCO is lower than that in YBCO. The reason is the renormalization factor z which is inverse of the mass-enhancement factor. The renormalization factor z in LSCO is smaller than that in YBCO, owing to the strong electron correlation in LSCO. Since the energy scale of qusi-particles is determined by z, the gap and Tc are determined by z.
5.This kind of renormalization is general in all the strongly correlated electron systems. We can explain Tc in organic superconductors and heavy fermions.
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