# Evidence of charge density wave with anisotropic gap in monolayer VTe$_2$ film

## TL;DR

This study provides experimental evidence of a charge density wave with an anisotropic gap in monolayer VTe2, highlighting the roles of Fermi surface nesting and electron-phonon interactions in its formation.

## Contribution

It is the first to observe and characterize the anisotropic CDW gap in monolayer VTe2 using multiple experimental techniques and theoretical calculations.

## Key findings

- Charge density wave transition at 186 K in monolayer VTe2.
- Anisotropic CDW gap up to 50 meV observed.
- Phonon softening at the CDW wave vector supports the nesting mechanism.

## Abstract

We report experimental evidence of charge density wave (CDW) transition in monolayer 1T-VTe$_2$ film. 4$\times$4 reconstruction peaks are observed by low energy electron diffraction below the transition temperature $T_{CDW}$ = 186 K. Angle-resolved photoemission spectroscopy measurements reveal arc-like pockets with anisotropic CDW gaps up to 50 meV. The anisotropic CDW gap is attributed to the imperfect nesting of the CDW wave vector, and first-principles calculations reveal phonon softening at the same vector, suggesting the important roles of Fermi surface nesting and electron-phonon interaction in the CDW mechanism.