磁性拓扑绝缘体中的量子反常霍尔效应

Quantum anomalous Hall effect in magnetic topological insulators

摘要:

量子反常霍尔效应是一种不需要外磁场、具有手性边缘态的量子化霍尔效应,可以用于构建其他新奇量子态和发展未来低功耗电子学器件等.该全新的量子效应于2012年首先由中国科学家在五层Cr掺杂的(Bi,Sb)₂Te₃拓扑绝缘体薄膜中实现.在过去七年间,经过大家的努力,其观测温度从最初的30 mK已经提高到2 K左右,进一步提高量子反常霍尔效应的观测温度是目前该领域主要的研究方向之一,是许多拓扑量子效应走向应用的关键因素.本文主要总结了量子反常霍尔效应研究的实验进展,特别在提高其观测温度方面的研究进展.文章包括四个部分:前两个部分分别介绍磁性掺杂和磁性近邻拓扑绝缘体体系中量子反常霍尔效应研究,第三部分介绍最新发现的内禀磁性拓扑绝缘体体系,最后一部分对设计和构造高温量子反常霍尔效应系统的原理和路线图给出一些建议和展望.

Abstract:

The quantum anomalous Hall effect (QAHE) is a quantized Hall effect without external magnetic field, which has chiral edge states and can be used for developing low consumption electronic devices and constructing other novel quantum states. At the end of 2012, the QAHE was first observed by Chinese scientists in Cr-doped (Bi,Sb)₂Te₃ topological insulator thin films. In the past seven years, the observation temperature has been raised from 30 mK to about 2 K. Further raising observation temperature is essential for the applications of many quantum effects, which is one of the major research directions in the field of topological quantum physics and materials. In this review, we summarize the experimental progresses in the study of QAHE in magnetic topological insulators, especially in the aspect of QAHE observation temperature. The article consists of four parts: in the first two parts, the QAHE in doping and proximity-effect induced magnetic topological insulators is introduced. In the third part, the newly discovered intrinsic magnetic topological insulator system is presented. The last part gives some perspectives about possible principle and roadmap of how to design and build QAH systems at high temperatures.