Relaxation dynamics in quantum electron-glasses

TL;DR

This paper demonstrates that the relaxation dynamics of quantum electron-glasses depend on carrier concentration, with some systems showing slowed relaxation at higher temperatures, explained by a dissipative tunneling model.

Contribution

It introduces a model linking relaxation behavior in electron-glasses to dissipative tunneling and carrier concentration effects, explaining differences in glassy behavior across materials.

Findings

Relaxation slows down with increasing temperature at certain carrier concentrations.

Dependence of relaxation time on carrier concentration is observed.

The dissipative tunneling model explains the observed dynamics.

Abstract

It is experimentally shown that, depending on the carrier-concentration of the system $n$, the dynamics of electron-glasses either \textit{slows down }with increasing temperature or it is \textit{independent} of it. This also correlates with the dependence of a typical relaxation time (or `viscosity') on $n$. These linked features are argued to be consistent with a model for dissipative tunneling. The slow relaxation of the electron glass may emerge then as a manifestation of friction in a many-body quantum system. Our considerations may also explain why strongly-localized granular metals are likely to show electron-glass effects while semiconductors are not.