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Theoretical Study of Kondo lattices by the 1/d expansion method

近藤晶格的 1/d 展开法理论研究

基本信息

批准号：
13640342
负责人：
OHKAWA Fusayoshi
金额：
$ 2.05万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

I have developed a theoiy of Kondo lattices for past 16 yeais ; an eaily theoiy of high-temperature superconductivity published in 1987 is also within this theoretical framework. I have applied the theory to the following five issues on strong election correlations : (1)Itinerant-electron ferromagnetism : The supeiexchange interaction can be ferromagnetic for multi-band models, when the Hund coupling is strong enough. The exchange interaction arising from the virtual exchange of pair excitations of quasiparticles can also be ferromagnetic, when the chemical potential is at one of the band edges, in particular, when a sharp peak of the density of states is there. These two exchange interactions are mainly responsible for ferromagnetism in itinerant-election systems. (2)Magnetic structures of itinerant-electron antiferromagnets : When there are equivalent nesting vectors, multiple Q spin density wave (SDW) states can be stabilized ; magnetizations with different Q should be orthogonal to each other for double or triple Q SDW. (3)Pseudogaps in normal states of high-temperature superconductors : Anisotropic pseudogaps can appear because of large life-time widths of quasiparticles, which are mainly caused by dγ-wave superconducting fluctuations. (4)Election-phonon interaction in high-temperature superconductors : I have proposed a novel electron-phonon interaction arising from the modulation of the superexchange interaction by phonons. This election-phonon interaction can explain kinks in the quasiparticle dispersion and the softening of phonons m cuprates. (5)Mott-Hubbard metal-insulator crossover in disordered Kondo lattices : The asymmetry of the crossovei between hole-doped and electron-doped cuprates can be explained by a theory of disordered Kondo lattices, if disorder of hole-doped cuprates is relatively larger than that of election-doped cuprates.

在过去的16年里，我发展了一套近藤格理论；1987年发表的一个早期的高温超导理论也在这个理论框架内。我将该理论应用于以下五个关于强选择相关性的问题：(1)流动电子铁磁性：当洪德耦合足够强时，多波段模型的超交换相互作用可以是铁磁性的。当化学势位于带的一个边缘时，特别是当态密度有一个尖峰时，由准粒子对激发的虚交换引起的交换相互作用也可以是铁磁性的。这两种交换相互作用是巡回选举系统中铁磁性的主要原因。(2)流动电子反铁磁体的磁性结构：当存在等效嵌套向量时，可以稳定多个Q自旋密度波（SDW）态；对于双Q或三Q SDW，不同Q的磁化强度应相互正交。(3)高温超导体正常状态下的赝隙：准粒子寿命宽度大，会出现各向异性赝隙，这主要是由dγ波超导波动引起的。(4)高温超导体中的选举-声子相互作用：我提出了一种新的电子-声子相互作用，它是由声子调制超交换相互作用引起的。这种选举-声子相互作用可以解释准粒子色散中的扭结和声子在铜酸盐中的软化。(5)无序近藤晶格中的Mott-Hubbard金属-绝缘体交叉：如果空穴掺杂铜酸盐的无序性相对于选举掺杂铜酸盐的无序性更大，则空穴掺杂铜酸盐和电子掺杂铜酸盐之间交叉的不对称性可以用无序近藤晶格理论来解释。