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Research on one particle picture near the localized-delocalized transition in the strongly correlated f-electron system

强关联f电子系统局域-离域转变附近的一幅粒子图像研究

基本信息

批准号：
16540316
负责人：
HARIMA Hisatomo
金额：
$ 2.37万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

The program code for electronic structure calculations with an FLAPW and an LDA+U method has been developed for strongly correlated electron systems, to treat the magnetic states. Then electronic structures are obtained for CeRu_2Si_2 in the region of meta magnetic transition, and for CeIn_3 under pressures. It revels that the results strongly depend on the magnitude of U and the applied magnetic field, so such the dependence should be investigated more. Now the electric field gradients(EFG) can be obtained even by the LDA+U method. It has been revealed that the asymmetry parameters strongly depend on the configurations for multi f states even for the singlet state under a cubic symmetry. This indicates that the EFG, directly compared with NQR frequencies, obtains important information to determine the configuration of the multi f electrons. On the other hand, the effective model for the crystalline electric filed (CEF) for the j-j coupling scheme has been developed, to solve the problem that the multi f electron states split by the CEF potential in the j-j coupling model are not compatible, even qualitatively, with those obtained in the LS coupling scheme. As well known, the non-Kramers doublet cannot be obtained for f^2 state in the j-j coupling scheme, because of no 6^<th> order term appearing in j=5/2 space. We have proposed that the term in the order of 1/lambda must be included in the CEF calculations, where lambda is the strength of the spin-orbit interactions, and assumed to be infinite in the j-j coupling scheme. This means that the contributions from j=7/2 are taken into account in the j-j coupling scheme. Then it is shown the results in our effective j-j model quantitatively agree with those in the LS coupling scheme, even for the T_h symmetry in filled skutterydutes.

针对强关联电子系统，采用FLAPW和LDA+U方法，编制了电子结构计算程序，处理了磁态。在此基础上，计算了CeRu_2Si_2在Meta磁性转变区的电子结构和CeIn_3在压力下的电子结构。结果表明，该结果强烈依赖于U的大小和外加磁场，因此这种依赖性需要进一步研究。现在甚至可以通过LDA+U方法来获得电场梯度（EFG）。结果表明，在立方对称性下，对于多个f态，甚至对于单重态，非对称性参数都强烈地依赖于组态。这表明，EFG直接与NQR频率比较，获得了确定多个f电子组态的重要信息。另一方面，为了解决j-j耦合模型中由晶电场势分裂的多个f电子态与LS耦合模型中得到的结果不相容的问题，本文提出了j-j耦合模型中有效的晶电场模型。众所周知，在j-j耦合方案中，由于在j=5/2的空间中没有出现6^阶项，所以不能得到f^2态的非Kramers双重态<th>。我们建议在CEF计算中必须包括1/lambda量级的项，其中lambda是自旋-轨道相互作用的强度，并且在j-j耦合方案中假定为无限大。这意味着在j-j耦合方案中考虑了j=7/2的贡献。结果表明，即使对于填充Skutterydutes中的T_h对称性，我们的有效j-j模型的结果也与LS耦合方案的结果在定量上一致。

项目成果

期刊论文数量（53）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Magnetic Fluctuations of Filled Skutterudites Emerging in the Transition Region between Singlet and Triplet States

单重态和三重态过渡区出现的填充方钴矿的磁涨落

DOI：
发表时间：
2005
期刊：
Physical Review Letters 94・6
影响因子：
0
作者：
Katsunori Kubo;Takashi Hotta;B.Kalisky;Takashi Hotta
通讯作者：
Takashi Hotta

Microscopic Approach to Magnetism and Superconductivity of f-Electron Systems with Filled Skutterudite Structure

填充方钴矿结构 f 电子系统磁性和超导性的微观方法

DOI：
发表时间：
2005
期刊：
Journal of the Physical Society of Japan 74・4
影响因子：
0
作者：
Hiroaki Onishi;Takashi Hotta;M.Connolly;Takashi Hotta;H.Beidenkopf;Takashi Hotta
通讯作者：
Takashi Hotta

EFG at Sb Site of Filled Skutterudites

EFG 位于填充方钴矿 Sb 站点