Field-induced metal-insulator transition and switching phenomenon in correlated insulators

TL;DR

This paper investigates the electric field-induced metal-insulator transition in correlated insulators, revealing a first-order switching with hysteresis and the role of impurity-induced localized states in facilitating conductive pathways.

Contribution

It introduces a gauge-covariant Keldysh formalism to analyze the nonequilibrium transition and highlights the impact of impurities on switching behavior.

Findings

First-order transition with hysteresis at threshold electric field ~10^4 Vcm^{-1}

Localized mid-gap states enable resonant tunneling and filament formation

Switching occurs at lower fields than Zener breakdown

Abstract

We study the nonequilibrium switching phenomenon associated with the metal-insulator transition under electric field E in correlated insulator by a gauge-covariant Keldysh formalism. Due to the feedback effect of the resistive current I, this occurs as a first-order transition with a hysteresis of I-V characteristics having a lower threshold electric field (\sim 10^4 Vcm^{-1}) much weaker than that for the Zener breakdown. It is also found that the localized mid-gap states introduced by impurities and defects act as hot spots across which the resonant tunneling occurs selectively, which leads to the conductive filamentary paths and reduces the energy cost of the switching function.