Devil's Staircase in Semimetals

半金属的恶魔阶梯

基本信息

批准号：
07804020
负责人：
UEDA Kazuo
金额：
$ 1.34万
依托单位：
University of Tokyo
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 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07804020/
关键词：
Kondo lattice mode semimetal devil's staircas frustration CeSb RKKY interaction Friedel oscillations large Fermi surface デビルズステアケース CeBi CeP

项目摘要

Among the magnetic materials known so far, CeSb has the most complex phase diagram as a function of temperature and magnetic field. The complex magnetic phase diagram is know as the devil's staircase. Generally, the series of CeX (X=P,As, Bi, Sb) have complex magnetic phase diagrams in different degree, which suggeststhat there is a common mechanism for the devil's staircase observed in CeX.A characteristic feature of CeX is smallness of carriers. The carriers of CeX consist of holes at the GAMMA point and electrons at the X points. Under this situation, a new type of scattering processes from holes to electrons and vice versa accompanied by spin exchange with f-spins. This process may be calledoff-diagonal exchange in contrast to the usual exchanges where the scattering are within a band. The momentum transfer associated with his off-diagonal exchange corresponds to the antiferromagnetic wave vector, favoring antiferromagnetic RKKY interaction among the f spins. On the other hand, the ordinary exchanges favor ferromagnetic coupling in the low carrier limit. In this project, we have shown that the frustration between the RKKY interactions originated from these two types of exchange mechanisms is the basic mechanism for the devil's staircase in CeX by using a simple one-dimensional model.Since the origin of the RKKY interaction can be traced back to the Friedel oscillations, we have proceeded to study the spin and charge Friedel oscillations in the Kondo lattice model. By using thedensity matrix renormalization group method, we have observed spin and charge Friedel oscillations. From the period it is concluded that the Fermi volume is large in the sense that the Fermi wavevector isdetermined by the sum of densities of conduction electrons and localized spins.

在到目前为止已知的磁性材料中，CESB具有最复杂的相图作为温度和磁场的函数。复杂的磁相图被称为魔鬼的楼梯。通常，CEX系列（x = p，a，bi，sb）具有不同程度的复杂磁相图，这表明在CEX中观察到的魔鬼的楼梯有一个共同的机制。。 CEX的载体由伽马点的孔和X点的电子组成。在这种情况下，从孔到电子的新型散射过程，反之亦然，并伴有与F-Spins的自旋交换。与散射在频段内的通常交换相反，此过程可能称为off-diagonal交换。与他的非对角线交换相关的动量转移对应于抗磁性波载体，有利于F旋转之间的抗铁磁rkky相互作用。另一方面，普通交换有利于低载体极限的铁磁耦合。在这个项目中，我们已经表明，源自这两种类型的交换机制的rkky互动之间的挫败感是CEX中魔鬼楼梯的基本机制，它通过使用简单的一维模型。因为rkky互动的起源可以是追溯到弗里德尔振荡，我们开始研究昆多晶格模型中的自旋和弗里德尔振荡。通过使用TheDenty矩阵重新归一化组方法，我们观察到了自旋和充电弗里德尔振荡。从结论开始，从传导电子和局部旋转的密度之和，费米的波形从某种意义上说，费米体积很大。