External field induced metal-to-insulator transition in dissipative Hubbard model

TL;DR

This paper develops a non-equilibrium impurity solver within dynamical mean-field theory to study electric field-induced metal-insulator transitions in correlated systems, revealing phase behavior similar to thermal transitions.

Contribution

It introduces a non-equilibrium steady-state non-crossing approximation impurity solver for DMFT, enabling accurate analysis of strongly correlated systems under electric fields.

Findings

Electric field induces a metal-insulator transition similar to thermal effects.

The phase diagram shows coexistence regions between metallic and insulating states.

The approach improves upon previous methods like IPT in describing non-equilibrium transitions.

Abstract

In this work, we develop a non-equilibrium steady-state non-crossing approximation (NESS-NCA) impurity solver applicable to general impurity problems. The choice of the NCA as the impurity solver enables both a more accurate description of correlation effects with larger Coulomb interaction and scalability to multi-orbital systems. Based on this development, we investigate strongly correlated non-equilibrium states of a dissipative lattice system under constant electric fields. Both the electronic Coulomb interaction and the electric field are treated non-perturbatively using dynamical mean-field theory in its non-equilibrium steady-state form (NESS-DMFT) with the NESS-NCA impurity solver. We validate our implementation using a half-filled single-band Hubbard model attached to a fictitious free Fermion reservoir, which prevents temperature divergence. As a result, we identify metallic and insulating phases as functions of the electric field and the Coulomb interaction along with a phase coexistence region amid the metal-to-insulator transition (MIT). We find that the MIT driven by the electric field is qualitatively similar to the equilibrium MIT as a function of temperature, differing from results in previous studies using the iterative perturbation theory (IPT) impurity solver. Finally, we highlight the importance of the morphology of a correlated system under the influence of an electric field.