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Spin-orbital entanglement and dynamic properties of spin-orbital systems

自旋轨道纠缠和自旋轨道系统的动力学性质

基本信息

批准号：
153396866
负责人：
Professorin Dr. Maria Daghofer
金额：
--
依托单位：
Institut für Funktionelle Materie und Quantentechnologien
依托单位国家：
德国
项目类别：
Independent Junior Research Groups
财政年份：
2009
资助国家：
德国
起止时间：
2008-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/153396866?language=en
关键词：
Spin orbital entanglement dynamic properties

项目摘要

In transition metal oxides, quantum effects and correlations between electrons lead to a large variety of material properties. While they can in some cases be described by one-band models where the only relevant properties of the electrons are their spin and charge, some materials have another degree of freedom: the orbital occupied by the electron. With strong Coulomb repulsion, this leads to spin-orbital physics, where spin and orbital degrees of freedom are entangled. I propose to calculate dynamic susceptibilities for realistic models describing spin-orbital systems. Such calculations are necessary to describe and understand experiments like angle resolved photoemission spectroscopy (ARPES) or neutron scattering and also give information about fundamental excitations. While analytic methods exist for special cases in one dimension, I propose to use numerical methods based on exact diagonalization and cluster-embedding, especially the variational cluster approach. They can be applied to more general and realistic models and can also be used in higher dimensions. Recently, superconductivity has been investigated in iron-pnictides, where several bands cross the Fermi energy, suggesting that the orbital degree of freedom is relevant. The proposed project also includes work on orbital models for pnictides and on the temperature dependence of the magnetic susceptibility.

在过渡金属氧化物中，量子效应和电子之间的相关性导致了各种各样的材料性质。虽然在某些情况下，它们可以用单能带模型来描述，其中电子的唯一相关性质是它们的自旋和电荷，但有些材料还有另一个自由度：电子占据的轨道。由于强烈的库仑排斥，这导致了自旋-轨道物理学，其中自旋和轨道自由度纠缠在一起。我建议计算描述自旋-轨道系统的现实模型的动态磁化率。这样的计算对于描述和理解角分辨光电子能谱（ARPES）或中子散射等实验是必要的，并且也给出了关于基本激发的信息。虽然分析方法存在的特殊情况下，在一维，我建议使用数值方法的基础上精确对角化和集群嵌入，特别是变分聚类方法。它们可以应用于更一般和更真实的模型，也可以用于更高的维度。最近，人们研究了铁磷族化合物的超导电性，其中有几个带穿过费米能，这表明轨道自由度是相关的。拟议的项目还包括关于磷属元素潮汐轨道模型和磁化率温度依赖性的工作。