The Memory Effect in Electron Glasses

TL;DR

This paper develops a theoretical model explaining the memory effect in electron glasses, linking the persistence of electronic correlations to the observed conductivity dip and its dependence on temperature and disorder.

Contribution

The paper introduces a new theory connecting long-time electronic correlations to the memory effect, including the saturation and erasure thresholds of the memory dip.

Findings

The theory reproduces the experimental scaling of the memory dip width.

It predicts the temperature dependence of the saturation threshold.

The model aligns with observed behavior of the anomalous field effect.

Abstract

We present a theory for the memory effect in electron glasses. In fast gate voltage sweeps it is manifested as a dip in the conductivity around the equilibration gate voltage. We show that this feature, also known as anomalous field effect, arises from the long-time persistence of correlations in the electronic configuration. We argue that the gate voltage at which the memory dip saturates is related to an instability caused by the injection of a critical number of excess carriers. This saturation threshold naturally increases with temperature. On the other hand, we argue that the gate voltage beyond which memory is erased, is temperature independent. Using standard percolation arguments, we calculate the anomalous field effect as a function of gate voltage, temperature, carrier density and disorder. Our results are consistent with experiments, and in particular, they reproduce the observed scaling of the width of the memory dip with various parameters.