# Doublon bottleneck in the ultrafast relaxation dynamics of hot electrons in 1T-TaS_2

## TL;DR

This study investigates the ultrafast relaxation of hot electrons in 1T-TaS_2, revealing a doublon bottleneck effect that influences electron lifetimes differently in metallic and Mott insulating states.

## Contribution

It provides the first direct measurement of hot electron lifetimes in 1T-TaS_2 and introduces a Boltzmann model accounting for doublon-holon interactions in the Mott state.

## Key findings

- Hot electron lifetime is 12 fs in metallic state.
- Hot electron lifetime is 60 fs in Mott insulating state.
- Doublon-holon interactions explain relaxation dynamics.

## Abstract

Employing time-resolved photoelectron spectroscopy we analyze the relaxation dynamics of hot electrons in the charge density wave / Mott material 1T-TaS_2. At 1.2 eV above the Fermi level we observe a hot electron lifetime of 12 +- 5 fs in the metallic state and of 60 +- 10 fs in the broken symmetry ground state - a direct consequence of the reduced phase space for electron-electron scattering determined by the Mott gap. Boltzmann equation calculations which account for the interaction of hot electrons in a Bloch band with a doublon-holon excitation in the Mott state provide insight into the unoccupied electronic structure in the correlated state.