Quantum spin Hall insulator phase in monolayer WTe2 by uniaxial strain

Monolayer WTe2, which is predicted to be large-gap quantum spin Hall (QSH) insulators with distorted 1T (1T’) structure, attracts rapidly growing interests. However, the intrinsic semimetallic nature of the monolayer 1T’-WTe2 limits their direct applications based on QSH effect. By first-principles density functional theoretical calculations, we demonstrate a phase transition from semimetal to QSH insulator under the uniaxial strains along a and b axis in monolayer 1T’-WTe2. The electronic phase transition results from the geometric structure deformation upon the uniaxial strains. This suggests monolayer 1T’-WTe2 as a promising material for application in strain-tunable topological quantum electronics.