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Theory of Superconductivity of Strongly Correlated Electrons

强关联电子超导理论

基本信息

批准号：
09640460
负责人：
IKEDA Ryusuke
金额：
$ 1.92万
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：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

One of the most important subjects in high-T<@D2c@>D2 cuprates is to construct a correct theory of superconductivity close to the Mott transition, in particular, of so-called the pseudogap regime. First, we performed calculations of normal-Meissner transition temperature based on the strong-coupling approach for the d-p model and found that the true transition temperature T<@D2c@>D2 shows a quantitatively reasonable reduction, induced by superconducting fluctuation enhanced with decreasing the hole-doping, from the mean filed transition temperature. However, since the mutual repulsion between electrons was not directly included in the model, we could not obtain the expected behavior T<@D2c@>D2 (]SY.tri-substituted left.[) 0 near the half filling. To succeed in getting this result, we will need to develop a detailed superconductivity's theory based on the antiferromagnetic fluctuation (AFF) essential in the limit of vanishing holedoping. In this research, we developed such an AFF theory for the purpose of explaining strange behaviors of transport quantities, R<@D2xx@>D2, R<@D2xy@>D2, and R<@D2zz@>D2, in the normal phase of high-T<@D2c@>D2 cuprates and showed that apparently contradicting behaviors seen among data of these quantities can be explained within the present single theory.Another important subject in high-T_c superconductors is the problem of vortex states induced by the superconducting fluctuation in an applied magnetic field. Among unsolved issues in this subject, we have studied at this time the phase diagram of vortex states in fields parallel to the layers of a layered material such as high-T_c cuprates and the vortex glass transiton induced by correlated disorder and, for both issues, obtained theoretical results expected from available experimental data.

高T<@D2c@>D2铜酸盐中最重要的课题之一是构建接近莫特转变的正确超导理论，特别是所谓的赝能隙体系。首先，我们基于 d-p 模型的强耦合方法计算了法向迈斯纳转变温度，发现真实转变温度 T<@D2c@>D2 与平均场转变温度相比，由于空穴掺杂减少而增强的超导涨落引起的，在数量上呈现出合理的降低。然而，由于电子之间的相互排斥没有直接包含在模型中，因此我们无法在半填充附近获得预期的行为 T<@D2c@>D2 (]SY.tri-substitute left.[) 0 。为了成功获得这一结果，我们需要基于消失空穴掺杂极限中必需的反铁磁涨落（AFF）开发详细的超导理论。在这项研究中，我们开发了这样一个AFF理论，目的是解释在高T<@D2c@>D2铜酸盐正相中输运量R<@D2xx@>D2、R<@D2xy@>D2和R<@D2zz@>D2的奇怪行为，并表明这些量的数据之间明显矛盾的行为可以在现有的单一理论中解释。高温_c中的另一个重要课题超导体是由外加磁场中的超导涨落引起的涡旋态问题。在本课题中尚未解决的问题中，我们目前研究了与层状材料（例如高T_c铜酸盐）平行的场中涡旋态的相图以及由相关无序引起的涡旋玻璃转变，并且对于这两个问题，获得了从现有实验数据中预期的理论结果。