磁性掺杂拓扑绝缘体：量子化反常霍尔效应的材料设计

Quantized anomalous Hall effect is a quantized Hall conductance effect coming from spontaneous magnetization in the absence of an external magnetic field. Its physical nature is that the combination of spontaneous magnetization and spin-orbit coupling leads to a topologically nontrivial electronic structure. This project will leverage first-principles calculations to investigate that topological insulators β-Ag2Se、β-Ag2Te form magnetically ordered insulators when doped with transition metal elements (such as Co, etc.). In 2D film materials, this magnetic order probably results in the topologically nontrivial electronic structure, generating the quantized anomalous Hall effect. We will also detailedly study the synthesis conditions, doping phase diagrams, magnetic performance, Curie temperature and magnetic coupling mechanism of β-Ag2Se、β-Ag2Te systems doped with Co or other transition metal elements. Such material design will not only clarify the formation mechanism of magnetic insulating property of Co-doped β-Ag2Se system observed in experiments, but also provide theoretical indications for experiments on the realization and study of quantized anomalous Hall effect. Because this effect leverages electrical charge current, it's easy to make it compatible with present electronics technology. It will promote the development of a new generation low energy consumption transistor and electronics devices.

量子反常霍尔效应是在没有外磁场的情况下由自发磁化导致的量子化霍尔电导效应，其物理本质是自发磁化和自旋轨道耦合相互作用共同导致的拓扑非平庸的电子结构。本项目拟利用第一性原理计算，研究Co等过渡金属元素掺杂拓扑绝缘体β-Ag2Se、β-Ag2Te形成的磁序绝缘体。在其二维薄膜材料中，这种磁序极有可能导致拓扑非平庸的电子结构，产生量子反常霍尔效应。我们还将细致地研究Co及其他3d过渡金属元素掺杂β-Ag2Se、β-Ag2Te系统的合成条件、掺杂相图、磁性、居里温度、磁性耦合机制等。这样的材料设计，不但有望阐明实验上已发现的Co掺杂β-Ag2Se磁序绝缘体的产生机理，还会为实验实现和研究量子化反常霍尔效应提供理论指导。由于此效应利用的是电荷流，更易与现有的电子学技术兼容，它将推动新一代低能耗晶体管和电子学器件的发展。