Theory of Superconductivity of Strongly Correlated Electrons

在高T&lt；@D2C@&D2铜酸盐中，最重要的课题之一是建立一个接近Mott转变的超导电性的正确理论，特别是所谓的伪能隙区域。首先，我们基于d-p模型的强耦合方法对正常-迈斯纳转变温度进行了计算，发现真正的转变温度T&lt；@D2c@&gt；D2显示出从平均场转变温度到平均场转变温度的合理降低，这是由于超导涨落随着空穴掺杂的减少而增强。然而，由于电子之间的相互排斥没有直接包含在模型中，我们不能在半填充附近得到预期的行为T&lt；@D2c@&gt；D2(]SY.tri-取代Left.[)0。为了成功地得到这一结果，我们需要发展一种详细的超导理论，该理论基于零空穴掺杂极限中的反铁磁涨落(AFF)。在这项研究中，我们发展了这样一个AFF理论，目的是解释输运量R&lt；@D2XX@&gt；D2，R&lt；@D2xy@&gt；D2，和R&lt；@D2zz@&gt；D2，在高T&lt；@D2C@&gt；D2铜酸盐的正常相中，R&lt；@D2xx@&gt；D2，和R&lt；@D2zz@&gt；D2，这些输运量的奇怪行为可以用目前的单一理论来解释。在本课题尚未解决的问题中，我们目前已经研究了层状材料平行于层的场中涡旋态的相图，如高T_c铜酸盐和由关联无序引起的涡旋玻璃跃迁，并对这两个问题从现有的实验数据中获得了预期的理论结果。

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.