Using a nonequilibrium implementation of the extended dynamical mean field theory (EDMFT) we simulate the relaxation after photo excitation in a strongly correlated electron system with antiferromagnetic spin interactions. We consider the t-J model and focus on the interplay between the charge- and spin-dynamics in different excitation and doping regimes. The appearance of string states after a weak photo excitation manifests itself in a nontrivial scaling of the relaxation time with the exchange coupling and leads to a correlated oscillatory evolution of the kinetic energy and spin-spin correlation function. A strong excitation of the system, on the other hand, suppresses the spin correlations and results in a relaxation that is controlled by hole scattering. We discuss the possibility of detecting string states in optical and cold atom experiments.
@article{arxiv.1803.02071,
title = {Coupled charge and spin dynamics in a photo-excited Mott insulator},
author = {Nikolaj Bittner and Denis Golež and Hugo U. R. Strand and Martin Eckstein and Philipp Werner},
journal= {arXiv preprint arXiv:1803.02071},
year = {2018}
}