Strain tuning of charge density wave and Mott-insulating states in monolayer VTe ₂

Abstract Monolayer vanadium ditelluride (VTe 2 ) exhibits a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> <mml:mo>×</mml:mo> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> </mml:mrow> </mml:math> charge-density-wave (CDW) order intertwined with a Mott-insulating state. However, the physical mechanisms driving the emergence of the CDW order and the 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 VTe 2 under applied biaxial strain. Our results reveal that the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> <mml:mo>×</mml:mo> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> </mml:mrow> </mml:math> CDW phase is metastable in free-standing monolayer VTe 2 but becomes stabilized under compressive strain below ε = −2%. The formation of the CDW order originates predominantly from strong EPC, rather than from Fermi-surface nesting. The narrowing of the bandwidth due to the CDW order, combined with correlation effects associated with the V 3d orbitals, collectively drive the system into a Mott-insulating state. Furthermore, we find that tensile strain suppresses the CDW order and induces a superconducting state above a critical strain threshold ( ε = 2%). These findings enhance our understanding of correlation physics in monolayer VTe 2 and provide a pathway for strain-engineered manipulation of quantum phases in two-dimensional transition-metal dichalcogenides.