Thermalization Processes in Interacting Anderson Insulators

TL;DR

This study investigates energy absorption and thermalization in interacting Anderson insulators, revealing that in strongly localized regimes, energy spectrum discreteness suppresses electron-electron interactions, with thermalization depending on phonon coupling.

Contribution

It provides experimental evidence that energy absorption and thermalization in Anderson insulators are influenced by many-body effects and proximity to the mobility edge, challenging single-particle models.

Findings

Energy spectrum is discrete in strongly localized regimes.

Inelastic electron-electron events are suppressed at low temperatures.

Energy absorption persists at higher frequencies near the mobility edge.

Abstract

This paper describes experiments utilizing a unique property of electron-glasses to gain information on the fundamental nature of the interacting Anderson-localized phase. The methodology is based on measuring the energy absorbed by the electronic system from alternating electromagnetic fields as function of their frequency. Experiments on three-dimensional (3D) amorphous indium-oxide films suggest that, in the strongly localized regime, the energy spectrum is discrete and inelastic electron-electron events are strongly suppressed. These results imply that, at low temperatures, electron thermalization and finite conductivity depend on coupling to the phonon bath. The situation is different for samples nearing the metal-insulator transition; in insulating samples that are close to the mobility-edge, energy absorption persists to much higher frequencies. Comparing these results with previously studied 2D samples [Ovadyahu, Phys. Rev. Lett., 108, 156602 (2012)] demonstrates that the mean-level spacing (on a single-particle basis) is not the only relevant scale in this problem. The possibility of de-localization by many-body effects and the relevance of a nearby mobility-edge (which may be a many-body edge) are discussed.