Topological Phases in Transition Metal Chalcogenides
Speaker: Junwei Liu (Hong Kong University of Science and Technology)
Time: September 01, 2017 10:00
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. Based on first-principles calculations, we predict monolayer MX2 (M=Mo, W; X=S, Se, Te) of 1T’ structure could exhibit quantum spin Hall effect. 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.