# Transient Hot Electron Dynamics in Single-Layer TaS$_2$

## TL;DR

This study investigates how femtosecond laser pulses induce transient electronic and band structure changes in single-layer TaS$_2$, revealing temperature-induced shifts and screening effects through photoemission spectroscopy and modeling.

## Contribution

It provides a detailed analysis of ultrafast electronic dynamics and band shifts in single-layer TaS$_2$ using time- and angle-resolved photoemission spectroscopy combined with semi-empirical modeling.

## Key findings

- Valence band shifts up to 150 meV after excitation
- Electronic temperatures exceed 3000 K
- Chemical potential shift dominates the electronic response

## Abstract

Using time- and angle-resolved photoemission spectroscopy, we study the response of metallic single layer TaS$_2$ in the 1H structural modification to the generation of excited carriers by a femtosecond laser pulse. A complex interplay of band structure modifications and electronic temperature increase is observed and analyzed by direct fits of model spectral functions to the two-dimensional (energy and $k$-dependent) photoemission data. Upon excitation, the partially occupied valence band is found to shift to higher binding energies by up to 150 meV, accompanied by electronic temperatures exceeding 3000~K. These observations are explained by a combination of temperature-induced shifts of the chemical potential, as well as temperature-induced changes in static screening. Both contributions are evaluated in a semi-empirical tight-binding model. The shift resulting from a change in the chemical potential is found to be dominant.