Fermi Surfaces of Magnetic Uranium Compounds

磁性铀化合物的费米面

基本信息

批准号：
06640471
负责人：
HASEGAWA Akira
金额：
$ 1.34万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

In order to carry out quantitative calculations of the electronic energy band structure for rare-earth and actinide compounds efficiently, a relativistic linearized augmented-plane-wave (RLAPW) method is made. The RLAPW method is applied to the cubic Laves phase Ce compounds such as CeRu_2, CeCo_2 and CeRh_2 which belong to the valence fluctuation regime. The energy band structures are calculated, and the Fermi surface is constructed. The Fermi surface consists of various sheets in each compound, which explain reasonably well the experimental results for the de Haas-van Alphen (dHvA) effect except the cyclotron effective masses. The same method is applied to calculate the energy band structure and the Fermi surface for the heavy-fermion U compound UPt_3. Although the experimental results for the dHvA effect are explained qualitatively well, there remain some dHvA branches whose origins are not clear. This result implies the limitations of the method, because it neglects the antiferromagnetic structure which exists in UPt_3 in reality. Then, in order to calculate the relativistic and spin-polarized energy band structure, the usual density-functional theory is extended to a relativistic current-and spin-density-functional theory for the system of interacting electrons in an external electromagnetic field. The number density, the spin density and the orbital current density are used as basic variables to describe the Hamiltonian of the system. A generalized Hohenberg-Kohn theorem is shown to hold, and a single-particle equation of the Kohn-Sham-Dirac type is derived. The single-particle equation is represented in the form which is appropriate to an isolated atom or ion, and has the magnetic interaction similar to the Zeeman term in which the spin and the orbital angular momenta couple with an effective magnetic field. The single-particle equation can be formulated also for the electrons in a crystal, and the application of the RLAPW method to it is now in progress.

为了进行稀土和actacinide化合物的电子能带结构的定量计算，进行了相对论线性化的增强平面波（RLAPW）方法。 RLAPW方法应用于属于价波动式的Ceru_2，Ceco_2和CERH_2等立方LAVES CE化合物。计算能带结构，并构建费米表面。费米表面由每种化合物中的各种床单组成，这很好地解释了de haas-van alphen（DHVA）效应的实验结果。使用相同的方法来计算重铁液化合物UPT_3的能量带结构和费米表面。尽管DHVA效应的实验结果在质上很好地解释了，但仍有一些DHVA分支，其起源尚不清楚。该结果意味着该方法的局限性，因为它忽略了现实中UPT_3中存在的抗磁磁结构。然后，为了计算相对论和自旋偏振能带结构，通常的密度功能理论扩展到了相对论电流和旋转密度功能的理论，用于在外部电磁场中相互作用的电子系统。数量密度，旋转密度和轨道电流密度被用作描述系统的哈密顿量的基本变量。证明了广义的Hohenberg-Kohn定理可以保持，并得出了Kohn-Sham-Dirac类型的单粒子方程。单粒子方程的形式表示为孤立的原子或离子，其磁相互作用类似于Zeeman项，其中自旋和轨道角动量夫妇具有有效的磁场。单粒子方程也可以为晶体中的电子配制，现在正在进行RLAPW方法的应用。