Strain tuning of charge density wave and Mott-insulating states in monolayer VTe2

Abstract: Monolayer vanadium ditelluride (VTe2) exhibits a 2\sqrt{3}*2\sqrt{3} charge density wave (CDW) order intertwined with a Mott-insulating state. However, the physical mechanisms driving the emergence of CDW order and Mott-insulating state are still not well understood. In this study, we systematically investigate the electronic band structure, phonon dispersion, and electron-phonon coupling (EPC) of monolayer VTe2 under applied biaxial strain. Our results reveal that the CDW phase is metastable in free-standing monolayer VTe2 and becomes stabilized under compressive strain below {\epsilon} = -2%. The formation of CDW order originates dominantly from strong EPC effect, rather than Fermi surface nesting. The narrowing of the bandwidth due to the CDW order, combined with the correlation effect of the V-3d orbital, collectively drives the system into a Mott-insulating state. Furthermore, we find that tensile strain suppresses CDW order and induces a superconducting state above a critical strain threshold ({\epsilon} = 2%). These findings enhance our understanding of correlation physics in monolayer VTe2 and provide a pathway for strain-engineered manipulation of quantum phases in two-dimensional transition metal dichalcogenides.