权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Theoretical Study of Anomalous Metallic Propertices of Strongly Coupled Electrons.

强耦合电子反常金属性质的理论研究。

基本信息

批准号：
12640343
负责人：
KURODA Yoshihiro
金额：
$ 1.92万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The pseudpgap in the single particle spectrum induced by the superconducting fluctuation together with the antiferromagnetic spin fluctuation has been believed to play key roles to determine essential features of anomalous properties of Cu-oxide high-T_c superconducting materials observed at temperatures higher than the superconducting transition temperature T_c. The roles are described as follows : In metals near Mott insulators, doped holes create new states inside the charge transfer gap called as ingap states, which have band width proportional to the hole doping rate δ and interact with each other through the superexchange interaction J_s enhanced by the antiferromagnetic spin fluctuation. This effective interaction promotes superconducting fluctuation, which induces a pseudogap in the single particle spectra. On the other hand, the pseudogap suppresses the spin fluctuation. Thus, effects of both of the spin fluctuation and the superconducting fluctuation need to be treated in a consistent way. In an underdoped system, the spin fluctuation dominates at higher temperatures, while the superconducting fluctuation or the pseudogap effect dominates at lower temperatures above T_c. This competition determines the anomalous temperature dependence of systems.We have demonstrated the senario to work explicitly by taking the d-p model with the help of the 1/N-expansion theory and calculating T_c, the NMR relaxation rate 1/T_1 and the single-particle spectra. We have treated the spin fluctuation in the renormalized random phase approximation and the superconducting fluctuation in the renormalized t-matrix approximation, where the effective pairing interactions are mediated by the renormalized spin fluctuation.

由超导涨落和反铁磁自旋涨落共同引起的单粒子能谱中的赝p能隙被认为是决定Cu氧化物高温超导材料在高于超导转变温度T_c时所观察到的反常性质的关键因素。在Mott绝缘体附近的金属中，掺杂空穴在电荷转移能隙内产生新的态，称为Inap态，它们的带宽与空穴掺杂率δ成正比，并通过反铁磁自旋涨落增强的超交换相互作用J_s相互作用。这种有效的相互作用促进了超导涨落，从而在单粒子谱中产生赝能隙。另一方面，赝能隙抑制了自旋波动。因此，自旋涨落和超导涨落两者的影响需要以一致的方式处理。在欠掺杂系统中，在较高温度下，自旋涨落占主导地位，而在较低温度下，超导涨落或赝能隙效应占主导地位。我们采用d-p模型，借助于1/N-展开理论，计算了T_c、NMR弛豫速率1/T_1和单粒子谱，证明了该模型的正确性。我们处理了重整化无规相近似下的自旋涨落和重整化t矩阵近似下的超导涨落，其中有效对相互作用是由重整化自旋涨落介导的。