Effects of frustration on the nonequilibrium dynamics of photo-excited lattice systems

TL;DR

This study explores how lattice geometry influences the nonequilibrium relaxation dynamics of photo-excited carriers in a Hubbard model, highlighting the impact of geometric frustration on thermalization and carrier cooling.

Contribution

It introduces a nonequilibrium dynamical cluster approximation to compare relaxation in different lattice geometries, revealing the role of frustration in carrier dynamics.

Findings

Longer relaxation times in frustrated triangular lattices.

Reduced cooling efficiency due to spin background disorder.

Higher effective temperature of carriers in frustrated systems.

Abstract

We theoretically investigate the effects of the lattice geometry on the nonequilibrium dynamics of photo-excited carriers in a half-filled two-dimensional Hubbard model. Using a nonequilibrium generalization of the dynamical cluster approximation, we compare the relaxation dynamics in lattices which interpolate between the triangular lattice and square lattice configuration and thus reveal the role of the geometric frustration in these strongly correlated nonequilibrium systems. In particular, we show that the cooling effect resulting from the disordering of the spin background is less effective in the triangular case because of the frustration. This manifests itself in a longer relaxation time of the photo-doped population, as measured by the time-resolved photo-emission signal, and a higher effective temperature of the photo-doped carriers in the non-thermal steady state after the intra-Hubbard-band thermalization.