Linear temperature dependence of conductivity in the "insulating" regime of dilute two-dimensional holes in GaAs

TL;DR

This study reveals that dilute two-dimensional holes in GaAs exhibit a linear temperature dependence of conductivity in the insulating regime, challenging traditional hopping conduction models and suggesting strong interaction effects near Wigner crystallization.

Contribution

It demonstrates a linear temperature dependence of conductivity in the insulating regime of dilute 2D holes, indicating a novel transport mechanism influenced by strong interactions.

Findings

Conductivity varies linearly with temperature in the insulating regime.

Hopping conduction is not observed below a certain conductivity threshold.

Strong interactions near Wigner crystallization likely influence transport properties.

Abstract

The conductivity of extremely high mobility dilute two-dimensional holes in GaAs changes linearly with temperature in the insulating side of the metal-insulator transition. Hopping conduction, characterized by an exponentially decreasing conductivity with decreasing temperature, is not observed when the conductivity is smaller than $e^{2}/h$. We suggest that strong interactions in a regime close to the Wigner crystallization must be playing a role in the unusual transport.