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Theoretical Study of Nested Spin Fluctuations

嵌套自旋涨落的理论研究

基本信息

批准号：
07640477
负责人：
MIYAKE Kazumasa
金额：
$ 1.28万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640477/
关键词：
Nested Spin Fluctuations Cuprate high-T_c Superconductors Anomalous Metallic Phase near the Mott Transition Mott Transition in the Intermediate Coupling Regime Spin-Gap Behaviors Itinerant-Localized Duality Model V_2O_3 URu_2Si_2 量子臨界点擬

项目摘要

Through this three years project, it has been shown that the anomalous properties of high-T_c cuprates, such as spin-gap behaviors and spin-charge separation aspects, can be understood in a unified way by taking into account the effects of nested spin-fluctuations on the basis of the Fermi liquid theory. Namely, the origin of such anomalous behaviors has been shown to be attributed to the fact that the spectral weight of coherent spin fluctuations decreases in the low-energy regime because the Fermi surface of the quasiparticles is inevitably nested as the antiferromagnetic Mott insulating state is approached. At the same time, it has been pointed out that the incoherent part of spin fluctuations also plays a crucial role in order to understand these anomalous behaviors consistently.It was also shown that the anomalous behaviors of V_2O_3, which had been considered to be a typical example exhibiting the Mott transition, can be understood as those originating from the nested spin-fluctu … More ations.It was shown, on the basis of the Gutzwiller treatment of d-p model with reasonable values of parameters, that the high-T_c cuprates are the materials belonging to the intermediate coupling regime and their origin of Mott transition should be attributed to the antiferromagnetic correlations accompanied by the nesting of the Fermi surface.A microsopic justification of the Itinerant-Localized Duality Model, which had been offering the basis of a theory of nested spin-fluctuations in strongly correlated metals, was given by means of the skeleton-expansion method of Luttinger-Ward.The anomalous properties of weak magnetism of URu_2Si_2 was shown to be understood as a moment-induced mechanism of the crystal-field singlet ground state of f^2-configuration of U ion together with the nesting effect of a part of the Fermi surface. In particular, it was derived naturally that the magnetic-field dependence of T_N, the Neel temperature, and m (0), the ordered moment at T=0, are scaled by apparently different magnitudes of magnetic field. Less

通过这三年的工作表明，在费米液体理论的基础上，通过考虑嵌套自旋涨落的影响，可以统一地理解高T_c铜酸盐的反常性质，如自旋能隙行为和自旋-电荷分离方面。也就是说，这种反常行为的产生归因于这样一个事实，即在低能区，相干自旋涨落的谱权重减小，因为随着反铁磁Mott绝缘态的逼近，准粒子的费米面不可避免地被嵌套。同时指出，自旋涨落的非相干部分对于解释这些反常行为也起到了至关重要的作用。同时还表明，V_2O_3的反常行为可以理解为源自嵌套的自旋-荧光…的反常行为，该反常行为被认为是Mott相变的典型例子在对d-p模型进行合理参数取值的Gutzwill er处理的基础上，证明了高T_c铜酸盐是属于中间耦合区域的物质，它们的Mott相变的起源应归因于伴随着费米表面嵌套的反铁磁关联。对巡回-定域对偶模型进行了微观论证，该模型为强关联金属中嵌套自旋涨落理论提供了基础，用Luttinger-Ward骨架展开法给出了Uu_2Si_2的弱磁性反常性质，并将其解释为U离子f^2组态的晶场单重态基态的力矩诱导机制和部分费米面的嵌套效应。特别地，自然地推导出T_N、Neel温度和T=0时的有序矩m(0)的磁场依赖关系是由明显不同的磁场大小决定的。较少