Hot carrier-assisted switching of the electron-phonon interaction in 1$T$-VSe$_2$

TL;DR

This study uses ultrafast spectroscopy and theoretical calculations to show how intense laser pulses induce hot carrier dynamics in 1T-VSe2, disrupting electron-phonon interactions and creating a new quasi-equilibrium state.

Contribution

It demonstrates how hot carriers affect phonon dispersion and electron-phonon interactions in 1T-VSe2, revealing a new state induced by laser excitation.

Findings

Hot carriers heat the lattice above the charge density wave temperature within 200 fs.

Hot carriers modify phonon dispersion and suppress low-energy acoustic phonon scattering.

A new quasi-equilibrium state is observed after laser perturbation.

Abstract

We apply an intense infrared laser pulse in order to perturb the electronic and vibrational states in the three-dimensional charge density wave material 1$T$-VSe$_2$. Ultrafast snapshots of the light-induced hot carrier dynamics and non-equilibrium quasiparticle spectral function are collected using time- and angle-resolved photoemission spectroscopy. The hot carrier temperature and time-dependent electronic self-energy are extracted from the time-dependent spectral function, revealing that incoherent electron-phonon interactions heat the lattice above the charge density wave critical temperature on a timescale of $(200 \pm 40)$~fs. Density functional perturbation theory calculations establish that the presence of hot carriers alters the overall phonon dispersion and quenches efficient low-energy acoustic phonon scattering channels, which results in a new quasi-equilibrium state that is experimentally observed.