Role of impact ionization in the thermalization of photo-excited Mott insulators

TL;DR

This paper investigates how impact ionization influences the thermalization process in photo-excited Mott insulators, revealing two distinct relaxation timescales affected by carrier energy, gap size, and doping levels.

Contribution

It demonstrates the role of impact ionization in the thermalization dynamics of Mott insulators, highlighting the dependence on carrier energy and system parameters.

Findings

Impact ionization causes rapid doublon-hole pair creation.

Thermalization involves two timescales: fast impact ionization and slower scattering.

Slow dynamics are sensitive to gap size and doping concentration.

Abstract

We study the influence of the pulse energy and fluence on the thermalization of photo-doped Mott insulators. If the Mott gap is smaller than the width of the Hubbard bands, the kinetic energy of individual carriers can be large enough to produce doublon-hole pairs via a process analogous to impact ionization. The thermalization dynamics, which involves an adjustment of the doublon and hole densities, thus changes as a function of the energy of the photo-doped carriers and exhibits two timescales -- a fast relaxation related to impact ionization and a slower timescale associated with higher-order scattering processes. The slow dynamics depends more strongly on the gap size and the photo-doping concentration.