Electrically driven insulator-to-metal transition in a correlated insulator: Electronic mechanism and thermal description

TL;DR

This paper investigates how strong electric fields induce insulator-to-metal and metal-to-insulator transitions in a correlated electron model, revealing that both can be understood through an effective temperature framework.

Contribution

It introduces a unified non-equilibrium framework to explain electrically-driven resistive switching in transition-metal oxides, combining heating and non-equilibrium effects.

Findings

Electric fields can induce both insulator-to-metal and metal-to-insulator transitions.

Transitions are driven by different mechanisms: heating versus non-equilibrium effects.

Both transitions can be described using an effective temperature approach.

Abstract

Motivated by the resistive switchings in transition-metal oxides (TMOs) induced by a voltage bias, we study the far-from-equilibrium dynamics of an electric-field-driven strongly-correlated model featuring a first-order insulator-to-metal transition at equilibrium, namely the dimer-Hubbard model. We use a non-equilibrium implementation of the dynamical cluster approximation to access the steady-state spectral and transport properties. We show that the electric field can drive both metal-to-insulator and insulator-to-metal transitions. While they proceed by quite distinct mechanisms, specifically simple heating of the metal versus non-equilibrium effects in the correlated charge gap, we show that both of these non-equilibrium transitions can be unified in a single framework once the excitations are accounted for in terms of an effective temperature. This conceptual advance brings together the two sides of the long-lasting debate over the origins of the electrically-driven resistive switching in TMOs.