Nonequilibrium response of an electron mediated charge-density-wave-ordered material to a large dc electric field

TL;DR

This paper uses advanced nonequilibrium dynamical mean-field theory to analyze how charge-density-wave materials respond to large electric fields, revealing anomalous behaviors like subgap states affecting transport.

Contribution

It develops a formalism to exactly solve the nonlinear response of charge-density-wave systems under strong electric fields, focusing on the Falicov-Kimball model.

Findings

Identification of subgap density of states increasing with temperature

Significant impact of subgap states on nonlinear transport

Development of a formalism applicable to all models

Abstract

Using the Kadanoff-Baym-Keldysh formalism, we employ nonequilibrium dynamical mean-field theory to exactly solve for the nonlinear response of an electron-mediated charge-density-wave-ordered material. We examine both the dc current and the order parameter of the conduction electrons as the ordered system is driven by the electric field. Although the formalism we develop applies to all models, for concreteness, we examine the charge-density-wave phase of the Falicov-Kimball model, which displays a number of anomalous behaviors including the appearance of subgap density of states as the temperature increases. These subgap states should have a significant impact on transport properties, particularly the nonlinear response of the system to a large dc electric field.