Mn-Bi-Te系列磁性拓扑绝缘体的电子结构与量子输运研究

Mn-Bi-Te系列化合物是第一种本征磁性拓扑绝缘体，是目前唯一能够同时实现量子反常霍尔效应和轴子绝缘体相的单一材料体系，也是目前最有希望实现高温量子反常霍尔效应的拓扑材料。最近，项目组通过角分辨光电子能谱等技术在国际上首次发现Mn-Bi-Te系列化合物表面态能隙在无掺杂时为零，但随着Sb掺杂浓度增加而增加，并对其存在性和变化规律提出了全新的见解。本项目拟从材料生长和制备开始，综合运用ARPES、STM以及输运和磁性测量等多种技术，从电子学结构、原子和磁矩的精确分布和重构、宏观输运和磁性行为等多个角度研究Mn-Bi-Te系列磁性拓扑绝缘体的拓扑性质和宏观量子效应。研究目标聚焦于拓扑性质和磁性能隙的指认和调控，以寻找其表面态能隙变化的起源和机理，探讨其实现高温量子反常霍尔效应的可能性，为本征磁性拓扑材料的实际应用奠定科学基础。

The Mn-Bi-Te layered compounds are the first series of intrinsic magnetic topological insulators. They are currently the only single material system capable of achieving both the quantum anomalous Hall effect (QAHE) and the axion insulator phase, and the most promising to achieve high temperature QAHE. Recently, the project team found for the first time through angle-resolved photoelectron spectroscopy that the surface state energy gap of the Mn-Bi-Te system is zero for the undoped compounds, but increases with the increase of Sb doping concentration, putting forward new insights into the existence and evolution of the gap. This project intends to start with the growth of materials, using comprehensively a variety of experimental techniques such as photoelectron spectroscopy, scanning tunneling microscopy, and transport and magnetic measurements, to study their precise electronic structure in the real and momentum space. The topological properties and macroscopic quantum effects of these materials are examined from multiple perspectives, such as the distribution and reconstruction of the atomic and magnetic moments, and the macroscopic transport and magnetic behavior of bulk materials or films. The research objectives focus on the identification and regulation of the magnetic gap, the confirmation of the topological properties, and the quantitative analysis of its sensitivity to the detailed structural parameters of the system, in order to pinpoint the origin and mechanism of the evolution of surface state energy gap, and explore the possibility of realizing high temperature QAHE, laying a scientific foundation for the practical application of intrinsic magnetic topological materials.