在生长于TiSe衬底上的α-BiBr纳米线上对拓扑边缘态的观测。

Observation of Topological Edge States on α-BiBr Nanowires Grown on TiSe Substrates.

作者信息

Peng Xianglin, Zhang Xu, Dong Xu, Ma Dashuai, Chen Dongyun, Li Yongkai, Li Ji, Han Junfeng, Wang Zhiwei, Liu Cheng-Cheng, Zhou Jinjian, Xiao Wende, Yao Yugui

机构信息

Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing, 100081, China.

Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, China.

出版信息

J Phys Chem Lett. 2021 Nov 4;12(43):10465-10471. doi: 10.1021/acs.jpclett.1c02586. Epub 2021 Oct 21.

DOI:10.1021/acs.jpclett.1c02586

PMID:34672593

Abstract

A time-reversal invariant two-dimensional (2D) topological insulator (TI) is characterized by the gapless helical edge states propagating along the perimeter of the system. However, the small band gap in the 2D TIs discovered so far hinders their applications. Recently, we predicted that single-layer BiBr is a 2D TI with a remarkable band gap and that α-BiBr crystals can host topological edge states at the step edges. Here we report the growth of α-BiBr nanowires with (102)-oriented top surfaces on the TiSe substrates and the direct observation of the predicted topological edge states at the step edges of the nanowires using scanning tunneling microscopy. The coupling between the edge states leads to the formation of surface states at the (102) top surfaces of the nanowires. Our work demonstrates the existence of topological edge states in α-BiBr and paves the way for developing α-BiBr-based devices for a high-temperature quantum spin Hall effect.

摘要

时间反演不变的二维（2D）拓扑绝缘体（TI）的特征是沿系统边界传播的无隙螺旋边缘态。然而，迄今为止发现的二维拓扑绝缘体中的小带隙阻碍了它们的应用。最近，我们预测单层溴化铋是一种具有显著带隙的二维拓扑绝缘体，并且α-溴化铋晶体在台阶边缘可以承载拓扑边缘态。在此，我们报告了在硒化钛衬底上生长具有（102）取向顶面的α-溴化铋纳米线，并使用扫描隧道显微镜直接观察到纳米线台阶边缘处预测的拓扑边缘态。边缘态之间的耦合导致在纳米线的（102）顶面上形成表面态。我们的工作证明了α-溴化铋中拓扑边缘态的存在，并为开发基于α-溴化铋的高温量子自旋霍尔效应器件铺平了道路。