Condensed Matter Seminar: Junwei Liu, MIT - “Topological Phases in Transition Metal Chalcogenides”

Event time: 
Thursday, May 25, 2017 - 1:00pm to 2:00pm
Sloane Physics Laboratory (SPL), 52 See map
217 Prospect St.
New Haven, CT 06511
Event description: 

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 realize Kane-Mele states and 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.

Keywords: WTe2, quantum spin Hall insulator, transition metal chalcogenides

[1] X. Qian, J. Liu, L. Fu, J. Li,Science 346, 1344 (2014)
[2] J. Liu, H. Wang, C. Fang, L. Fu, X. Qian, Nano Lett. 17 467-475 (2017)