Nonequilibrium steady-state theory of photodoped Mott insulators

TL;DR

This paper develops a steady-state theoretical framework using DMFT and NCA to study photodoped Mott insulators, revealing universal properties and hidden phases in a two-band Hubbard model.

Contribution

It introduces a non-equilibrium steady-state approach for photodoped Mott insulators, enabling efficient analysis of long-time behaviors and uncovering new phases.

Findings

Photodoped states can be described as non-equilibrium steady states with universal properties.

The method reveals hidden phases in a two-band Hubbard model with intertwined orders.

Stationary states are parametrized by effective temperature and charge excitation density.

Abstract

Photodoped states are widely observed in laser-excited Mott insulators, in which charge excitations are quickly created and can exist beyond the duration of the external driving. Despite the fruitful experimental explorations, theoretical studies on the microscopic models face the challenge to simultaneously deal with exponentially separated time scales, especially in multi-band systems, where the long-time behaviors are often well beyond the reach of state-of-the-art numerical tools. Here, we address this difficulty by introducing a steady-state description of photodoped Mott insulators using an open-system setup, where the photodoped system is stabilized as a non-equilirium steady-state (NESS) by a weak external driving. Taking advantage of the stationarity, we implement and discuss the details of an efficient numerical tool using the steady-state Dynamical Mean-Field Theory (DMFT), combined with the non-crossing approximation (NCA). We demonstrate that these stationary photodoped states exhibit the same properties of their transient counterparts, while being solvable with reasonable computational efforts. Furthermore, they can be parametrized by just few physical quantities, including the effective temperature and the density of charge excitations, which confirms the universal nature of photodoped states indeed independent of the excitation protocols. As a first application, we consider the stationary photodoped states in a two-band Hubbard model with intertwined spin-and-orbital ordering and find a family of hidden phases unknown from the previous studies, implying an apparently unexplored time regime of the relaxation of the intertwined orders.