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Theory of Superconductivity in Strongly correlated Electron Systems

强相关电子系统中的超导理论

基本信息

批准号：
15540340
负责人：
YAMADA Kosaku
金额：
$ 2.3万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540340/
关键词：
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 LS

项目摘要

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.

今年是我们项目的最后一年。我们正在完成强相关电子系统中超导性的研究。我们的理论总结如下几点。超导体的转变温度由库仑斥力U和质量增强因子1/ z2引起的电子相互作用的动量依赖决定。我们已经计算了自能项的四阶项。四阶项在给出实际的质量增强因子时起重要作用。利用四阶微扰理论，我们可以导出Dyson-Gorkov方程。通过求解该方程，我们可以讨论重整化因子和准粒子间各向异性相互作用的作用。我们可以解释为什么LSCO中的Tc比YBCO中的Tc低。原因是重整化因子z与质量增强因子相反。LSCO的重整因子z比YBCO小，这是由于LSCO的电子相关性强。由于准粒子的能量尺度由z决定，因此间隙和Tc由z.5决定。这种重整化在所有强相关电子系统中都是普遍存在的。我们可以解释有机超导体和重费米子中的Tc。