Non-linear effects and dephasing in disordered electron systems

TL;DR

This paper presents a comprehensive analysis of dephasing mechanisms in disordered electron systems using the Keldysh formalism, highlighting effects of external fields and inelastic scattering on weak localization and interaction corrections.

Contribution

It unifies the treatment of weak localization and interaction effects, deriving new expressions for field effects and clarifying dephasing time definitions in different channels.

Findings

External oscillating fields suppress weak localization.

Static electric fields can suppress interaction corrections.

Different dephasing times are identified in particle-particle and particle-hole channels.

Abstract

The calculation of the dephasing time in electron systems is presented. By means of the Keldysh formalism we discuss in a unifying way both weak localization and interaction effects in disordered systems. This allows us to show how dephasing arises both in the particle-particle channel (weak localization) and in the particle-hole channel (interaction effect). First we discuss dephasing by an external field. Besides reviewing previous work on how an external oscillating field suppresses the weak localization correction, we derive a new expression for the effect of a field on the interaction correction. We find that the latter may be suppressed by a static electric field, in contrast to weak localization. We then consider dephasing due to inelastic scattering. The ambiguities involved in the definition of the dephasing time are clarified by directly comparing the diagrammatic approach with the path-integral approach. We show that different dephasing times appear in the particle-particle and particle-hole channels. Finally we comment on recent experiments.