Nonthermal symmetry broken states in the strongly interacting Hubbard model

TL;DR

This paper investigates how the antiferromagnetic order in the Hubbard model evolves after interaction quenches, revealing nonthermal states with persistent order even under strong excitation, using nonequilibrium dynamical mean field theory.

Contribution

It demonstrates the existence of nonthermal symmetry-broken states in the Hubbard model post-quench, highlighting their stability and characteristics.

Findings

Nonthermal states are trapped after quenches from intermediate to strong interactions.

These states can exhibit robust antiferromagnetic order despite high excitation levels.

The decay of doublons protects the nonthermal ordered states.

Abstract

We study the time evolution of the antiferromagnetic order parameter after interaction quenches in the Hubbard model. Using the nonequilibrium dynamical mean field formalism, we show that the system, after a quench from intermediate to strong interaction, is trapped in a nonthermal state which is reminiscent of a photo-doped state and protected by the slow decay of doublons. If the effective doping of this state is low enough, it exhibits robust antiferromagnetic order, even if the system is highly excited and the thermal state thus expected to be paramagnetic. We comment on the implication of our findings for the stability of nonthermal superconducting states.