Junwei Liu, Hong Kong University of Science and Technology
The discovery of quantum spin Hall effect engendered a new chapter of topological materials research in condensed matter physics and materials science. In this talk, I will introduce some of our recent theoretical works about the topological phases in 2D and 3D transition metal chalcogenides. We predict monolayer MX2 (M=Mo, W; X=S, Se, Te) of 1T’ structure could realize quantum spin Hall insulator. Moreover, their topology can be easily tuned by external electric field, which motivated us to propose a new type of transistor, called topological field transistor. More recently, we found another new class of transition metal chalcogenides MM’Te4 (M=Nb, Ta; M’=Ir, Rh) could be quantum spin Hall insulators in 2D and Weyl semimetals in 3D. I will also discuss some recent transport, ARPES and STM experiments on monolayer WTe2, where many of the observations are consistent with monolayer WTe2 being a 2D TI. Finally, I will talk about our recent experimental and theoretical work about the strain effect on monolayer WTe2.
 X. Qian, J. Liu, L. Fu, J. Li，Science 346, 1344 (2014)
 J. Liu, H. Wang, C. Fang, L. Fu, X. Qian, Nano Lett. 17 467-475 (2017)
 C. Zhao, M. Hu, J. Liu and J. Jia (in preparation)
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