Enhancement of impact ionization in Hubbard clusters by disorder and next-nearest-neighbor hopping

TL;DR

This study uses exact diagonalization to explore how disorder and next-nearest-neighbor hopping enhance impact ionization in small Hubbard clusters subjected to electromagnetic pulses, revealing geometry-dependent effects.

Contribution

It demonstrates that disorder and next-nearest-neighbor hopping significantly enhance impact ionization in Hubbard clusters, with effects varying by geometry.

Findings

Impact ionization occurs in most geometries except 1D chains.

Next-nearest neighbor hopping enhances impact ionization.

Disorder and geometric frustration also promote impact ionization.

Abstract

We perform time-resolved exact diagonalization of the Hubbard model with time dependent hoppings on small clusters of up to $12$ sites. Here, the time dependence originates from a classic electromagnetic pulse, which mimics the impact of a photon. We investigate the behavior of the double occupation and spectral function after the pulse for different cluster geometries and on-site potentials. We find impact ionization in all studied geometries except for one-dimensional chains. Adding next-nearest neighbor hopping to the model leads to a significant enhancement of impact ionization, as does disorder and geometric frustration of a triangular lattice.