拓扑绝缘体电子结构磁性调控的第一性原理研究

项目名称： 拓扑绝缘体电子结构磁性调控的第一性原理研究

项目编号： No.11474197

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 罗卫东

作者单位： 上海交通大学

项目金额： 80万元

中文摘要： 拓扑绝缘体（TI）是新的量子物质，有很多新奇的物理性质，是当前凝聚态物理研究的热点。通过磁性破坏时间反演对称性，就有可能在TI的原狄拉克点打开带隙，进而可能实现量子反常霍尔效应、拓扑磁电效应等新奇量子现象，因此TI电子态的磁性调控具有重要意义。常见的磁性原子掺杂方法受到低掺杂浓度和空间无序分布的制约，其打开的带隙往往很小且空间分布不均，因此调控效果并不理想。本项目使用两种不同方案对TI的电子结构进行磁性调控：TI/磁性绝缘体异质结及天然超晶格磁性TI。运用第一性原理计算方法，本项目将研究TI/磁性绝缘体异质结以及天然超晶格磁性TI,在几个关键科学问题上取得进展:计算界面及天然超晶格磁性TI的结构稳定性；获得界面的磁交换耦合强度；研究磁各向异性与界面结构和化学组分的关系；最终理解原子结构、磁交换耦合、磁各向异性、电子结构的内在联系，预测具有量子反常霍尔效应和拓扑磁电效应的新体系。

中文关键词： 拓扑绝缘体；电子结构；第一性原理计算；磁交换耦合

英文摘要： Topological insulator is a new state of quantum matter with many novel physical properties, it is currently a research hotspot in condensed matter physics. By destroying time-reversal symmetry with magnetic field, a gap can be opened at the Dirac point of the topological insulator surface state,which could result in such novel quantum phenomena as the quantum anomalous Hall (QAH) effect and the topological magnetoelectric effect (TME). So it is important to understand the magnetic control of topological insulator electronic structures.Because of the low density and disorder effect of magnetic impurity, the often used method of magnetic impurity doping results in small and probably non-uniform surface gap.So it is not an ideal method to control topological insulator by magnetism.In this project we propose to use two different approaches to magnetically control the electronic structures of topological insulators: topological insulator/magnetic insulator heterostructures, and natural superlattice magnetic topological insulators. Using first-principles computational methods, we plan to study the topological insulator/magnetic insulator heterostructures and natural superlattice magnetic topological insulators. We plan to make progresses in several important problems: compute the structural stability of heterostructure and natural superlattice; obtain interfacial magnetic exchange coupling strength; study the relation between magnetic anisotropy and interface chemical composition; and, in the end, understand the relation between atomic structure, magnetic exchange coupling, magnetic anisotropy, and electronic structure. We will be able to theoretically predict new material systems with quantum anomalous Hall effect or topological magnetoelectric effect.

英文关键词： topological insulator;electronic structure;first-principles calculation;magnetic exchange coupling