Local engineering of topological phase in monolayer MoS2  

作　　者：Zhichang Wanga Xiaoqiang Liu Jianqi Zhu Sifan You Ke Bian Guangyu Zhang Ji Feng Ying Jiang 

机构地区：[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 [3]School of Physics and Electronic Engineering,Sichuan Normal University,Chengdu 610101,China [4]Collaborative Innovation Center of Quantum Matter,Beijing 100190,China [5]School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100190,China [6]CAS Center for Excellence in Topological Quantum Computation,University of Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Science Bulletin》2019年第23期1750-1756,共7页科学通报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (11888101, 11634001, 11834017 and 61888102);the National Key R&D Program (2016YFA0300901 and 2017YFA0205003);the Strategic Priority Research Program of Chinese Academy of Sciences (XDB28000000 and XDB30000000);Beijing Municipal Science & Technology Commission;support from National Science Fund for Distinguished Young Scholars (21725302);Cheung Kong Young Scholar Program

摘　　要：Monolayer transition metal dichalcogenides(TMDCs) with the 1 T0 structure are a new class of large-gap two-dimensional(2 D) topological insulators, hosting topologically protected conduction channels on the edges. However, the 1 T0 phase is metastable compared to the 2 H phase for most of 2 D TMDCs, among which the 1 T0 phase is least favored in monolayer MoS2. Here we report a clean and controllable technique to locally induce nanometer-sized 1 T0 phase in monolayer 2 H-MoS2 via a weak Argon-plasma treatment,resulting in topological phase boundaries of high density. We found that the stabilization of 1 T0 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 1 T0-2 H 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.Monolayer transition metal dichalcogenides（TMDCs） with the 1 T0 structure are a new class of large-gap two-dimensional（2 D） topological insulators, hosting topologically protected conduction channels on the edges. However, the 1 T0 phase is metastable compared to the 2 H phase for most of 2 D TMDCs, among which the 1 T0 phase is least favored in monolayer MoS2. Here we report a clean and controllable technique to locally induce nanometer-sized 1 T0 phase in monolayer 2 H-MoS2 via a weak Argon-plasma treatment,resulting in topological phase boundaries of high density. We found that the stabilization of 1 T0 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 1 T0-2 H 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.

关 键 词：Phase engineering Quantum spin Hall insulator Transition metal dichalcogenides Edge states Phase boundary 

分 类 号：TG1[金属学及工艺—金属学]