Theoretical Study of Exotic Superconductivity and Magnetism

奇异超导与磁性的理论研究

基本信息

批准号：
04640369
负责人：
MIYAKE Kazumasa
金额：
$ 0.77万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640369/
关键词：
Cuprate superconductor Nested Spin Fluctuations Anomalous Metallic Phase Normal State of Cuprates Itinerant-Localized Duality de Haas-van Alphen Effect in Superconducting State Anisotropic Superconductivity 型にはまらない超伝導スピンゆらぎ銅酸化物超伝導超伝

项目摘要

On the basis of analysis of the superconducting flusctuation effect on the NMR relaxation rate, which shows drastic decrease just above the transition temperature, it was found that the symmetry of the pairing of cuprate superconductor is favorable for d_<xy>pairing among the d-symmetry. We have performed a calculation for hole-number dependence of the transition temperature by taking into account the effect of the off-site repulsion U_<pd> between electrons on copper and oxygen. In the calculation, we follow the RPA treatment of U_<pd> after the strong on-site repulsion U_d is renormalized into the quasi-particle state. the results are in qualitative agreement with experiments. It was also found that the off-site repulsion U_<pd> easily destroy the d_<x2-y2> pairing.On the basis of research on the properties of antiferromagnetic nested spin fluctuations in 2D metals, it was found that the anomalous metallic phase observed in the normal state of cuprates, with aspects such as "spin gap … More " and "spin-charge separation", can be explained in a unified way as an effect of the mode-mode coupling of spin fluctuations on the itinerant-localized duality picuture when the renormalized Fermi surface is technically nested.In order to investigate the property of the de Haas-van Alphen (dHvA) effect in superconducting state, we have carried out the calculations adopting the Landau orbit as a basis of the single particle state. As a result, it turned out that the dHvA oscillations can be observed only in a very narrow region near the upper critical field if the symmetry of the pairing is isotropic s wave. This in turn shows that the anisotropic superconductivity, with the gap vanishing on the point (s) or line (s) on the Fermi surface, should be considered in the case the dHvA oscillations are observed well below the upper critical field.We have discussed the problem of the crossover between wavenumber-space pairing and real-space pairing being motivated by the fact that the cuprate superconductors, with very short coherence length of a few times the lattice constant, are expected to locate in the crossover region. The difficulty of the Nozieres & Schmitt-Rink theory applied to 2D case was analyzed critically. It was shown that its difficulty can be avoided when the supercounducting transition is treated in the Kosterlitz & Thouless formalism. Less

基于对NMR弛豫率的超导型振荡效应的分析，这表明在过渡温度之上急剧降低，发现Cuprate超导体配对的对称性有利于D_ <xy>对D-MemorgememeTry中的D_ <xy>配对。我们通过考虑了铜和氧气之间的电子拒绝u_ <pd>的影响，以计算过渡温度的孔数依赖。在计算中，我们遵循强烈的现场排斥u_d将U_ <pd>的RPA处理重归于准粒子状态。结果与实验达成了定性一致。 It was also found that the off-site repulsion U_<pd> easily destroy the d_<x2-y2> pairing.On the basis of research on the properties of antiferromagnetic nested spin fluctuations in 2D metals, it was found that the anomalous metallic phase observed in the normal state of cuprates, with aspects Such as "spin gap … More " and "spin-charge separation", can be explained in a unified way as当在技术上嵌套了自旋波动的模式模式耦合对静脉内的双重性图片的影响。在技术上是嵌套的。为了调查超导状态中的de haas-van alphen（DHVA）效应的特性，我们已经将计算采用了Landau Orbit作为单个粒子的基础。结果，事实证明，如果配对的对称是各向同性的S波，则只能在上临界场附近非常狭窄的区域观察到DHVA振荡。这反过来表明，在费米表面的点或线上的差距消失在费米表面上的差距消失，在这种情况下，DHVA振荡远低于上临界领域。几次晶格常数预计将位于跨界区域。批判性地分析了Nozieres＆Schmitt-Rink理论的难度。结果表明，当在Kosterlitz＆Thuless格式化中处理超级能源过渡时，可以避免它的困难。较少的