Slow relaxation of conductance of amorphous hopping insulators

TL;DR

This paper investigates how slow structural defect rearrangements in amorphous hopping insulators cause persistent memory effects in conductance, with conductance relaxing over time after abrupt voltage changes.

Contribution

It introduces a model linking defect dynamics to conductance relaxation, highlighting the role of structural rearrangements in memory effects in hopping insulators.

Findings

Conductance exhibits slow, time-dependent relaxation after voltage shifts.

Memory effects are due to structural defect rearrangements affecting hopping site populations.

The model explains the excess time-dependent conductivity observed in experiments.

Abstract

We discuss memory effects in the conductance of hopping insulators due to slow rearrangements of structural defects leading to formation of polarons close to the electron hopping states. An abrupt change in the gate voltage and corresponding shift of the chemical potential change populations of the hopping sites, which then slowly relax due to rearrangements of structural defects. As a result, the density of hopping states becomes time dependent on a scale relevant to rearrangement of the structural defects leading to the excess time dependent conductivity.