Local engineering of topological phase in monolayer MoS2

Zhichang Wang; Xiaoqiang Liu; Jianqi Zhu; Sifan You; Ke Bian; Guangyu Zhang; Ji Feng; Ying Jiang

doi:10.1016/j.scib.2019.10.004

Local engineering of topological phase in monolayer MoS₂

Sci Bull (Beijing). 2019 Dec 15;64(23):1750-1756. doi: 10.1016/j.scib.2019.10.004. Epub 2019 Oct 10.

Authors

Zhichang Wang¹, Xiaoqiang Liu¹, Jianqi Zhu², Sifan You¹, Ke Bian¹, Guangyu Zhang³, Ji Feng⁴, Ying Jiang⁵

Affiliations

¹ International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
² Beijing National Laboratory for Condensed Matter Physics and, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; School of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China.
³ Beijing National Laboratory for Condensed Matter Physics and, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China. Electronic address: gyzhang@iphy.ac.cn.
⁴ International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100190, China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China. Electronic address: jfeng11@pku.edu.cn.
⁵ International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100190, China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China. Electronic address: yjiang@pku.edu.cn.

PMID: 36659533
DOI: 10.1016/j.scib.2019.10.004

Abstract

Monolayer transition metal dichalcogenides (TMDCs) with the 1T' structure are a new class of large-gap two-dimensional (2D) topological insulators, hosting topologically protected conduction channels on the edges. However, the 1T' phase is metastable compared to the 2H phase for most of 2D TMDCs, among which the 1T' phase is least favored in monolayer MoS₂. Here we report a clean and controllable technique to locally induce nanometer-sized 1T' phase in monolayer 2H-MoS₂ via a weak Argon-plasma treatment, resulting in topological phase boundaries of high density. We found that the stabilization of 1T' phase arises from the concerted effects of S vacancies and the tensile strain. Scanning tunneling spectroscopy (STS) clearly reveals a spin-orbit band gap (~60 meV) and topologically protected in-gap states residing at the 1T'-2H phase boundary, which are corroborated by density-functional theory (DFT) calculations. The strategy developed in this work can be generalized to a large variety of TMDCs materials, with potentials to realize scalable electronics and spintronics with low dissipation.

Keywords: Edge states; Phase boundary; Phase engineering; Quantum spin Hall insulator; Transition metal dichalcogenides.