Polarization and ordering of conduction bands in highly concentrated f-electron systems

高浓度 f 电子系统中导带的极化和有序化

基本信息

批准号：
15340105
负责人：
KURAMOTO Yoshio
金额：
$ 4.93万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15340105/
关键词：
Kondo effect neutron scattering X-ray scattering quadrupole moment octupole moment hybridization interaction crystalline electric field magnetic form factor 中性子散乱

项目摘要

Variety of ordering phenomena and dynamics of f-electron systems were theoretically investigated paying special attention to the role of the spin degree of freedom of the conduction electrons, and following results were obtained.1.CeRh3B2 has the highest Curie temperature (120 K) as Ce compounds, and shows various anomalies such as the reverse-polarization of conduction electrons, strong anisotropy, and a small moment. We proposed a model which respects mixture between 4d molecular orbitals of Rh and 4f electron of flanking Ce ions, and explained this ferromagnetism in terms of a flat band mechanism.2.We have identified the order parameter of the phase IV of Cel-xLaxB6 as magnetic octupoles, which has been a longstanding mystery. Our model explains recent X-ray scattering results consistently. Our paper became an Editors' Choice in J.Phys.Soc.Jpn, and was reported by the press.3.The band calculation by dynamical mean-field theory was formulated, and the program code was developed. Previous theories could not take account of important spin-orbit interaction and the crystalline electric field effects. Quantitative calculations were performed by extending the NCA method, and incorporating this in the LMTO band calculation.4.Ternary Np compounds NpTGa5(T=Co, Ni, Rh) have been actively studied by neutron scattering. We have proposed a unified model that can explain a variety of magnetic orders of these compounds, and explained naturally complex ordered states. The Np orbital degrees of freedom are identified as the source of various magnetic orders, and a crystal deformation was predicted associated with the order.5.We have proposed the order parameters of Pr skutterudites as the scalar-type that keeps the cubic symmetry of the crystal. Our model naturally explains the NMR characteristics such as dependence on magnetic field direction, the anisotropy of the magnetization, and isotropic susceptibility.

从理论上研究了f电子系统的各种有序现象和动力学，特别关注传导电子自旋自由度的作用，得到了以下结果：1.CeRh3B2具有最高的居里温度（120 K）： Ce化合物表现出传导电子反极化、强各向异性、矩小等多种异常现象。我们提出了一个尊重 Rh 4d 分子轨道和侧翼 Ce 离子 4f 电子之间混合的模型，并用平带机制解释了这种铁磁性。2.我们将 Cel-xLaxB6 的 IV 相的有序参数确定为磁性八极子，这一直是个谜。我们的模型一致地解释了最近的 X 射线散射结果。我们的论文成为J.Phys.Soc.Jpn的编辑选择，并被媒体报道。3.制定了动态平均场理论的能带计算，并开发了程序代码。以前的理论无法考虑重要的自旋轨道相互作用和晶体电场效应。通过扩展NCA方法，并将其纳入LMTO能带计算中进行定量计算。4.三元Np化合物NpTGa5(T=Co，Ni，Rh)的中子散射研究非常活跃。我们提出了一个统一的模型，可以解释这些化合物的各种磁序，并解释自然复杂的有序态。 Np轨道自由度被确定为各种磁序的来源，并预测了与该序相关的晶体变形。 5.我们提出了Pr方钴矿的序参数为标量型，保持了磁序的立方对称性。水晶。我们的模型自然地解释了 NMR 特性，例如对磁场方向的依赖性、磁化强度的各向异性和各向同性磁化率。