Structural Phase Transition of Multilayer VSe2.

Vanadium diselenide (VSe2), a member of the transition metal dichalcogenides (TMDs) family, is emerging as a promising two-dimensional (2D) candidate for the electronic and spintronic device with exotic properties including charge/spin density wave and ferromagnetism. The bulk crystal VSe2 exists in a crystallographic form of 1T-phase with metallic behavior. In this paper, we report a structural phase transition of multilayer VSe2 from 1T to 2H through annealing at 650 K, accompanying a metal-insulator transition. We observe that the 2H-phase is more thermodynamically favorable than the 1T-phase at 2D.