The influence of a Coulomb gap in the whole variable range hopping regime

TL;DR

This paper presents a simple model describing the temperature-dependent electrical resistivity in insulators with a Coulomb gap, capturing the crossover between Efros-Shklovskii and Mott regimes and fitting various experimental data.

Contribution

The study introduces a unified function for resistivity that covers the entire variable range hopping regime, including crossover behaviors and gap parameter estimation.

Findings

The model fits experimental resistivity data across different regimes.

It explains crossover behavior between Efros-Shklovskii and Mott regimes.

Accounts for T^(-n) behaviors with 0.5<n<1 in experiments.

Abstract

The temperature dependence of the electrical resistivity in insulator systems with a Coulomb gap in the density of states is expressed by a very simple function which coincides with the Efros-Shklovskii T^(-1/2)result, at temperatures lower than some value Tlim. Above this limit it consists of the product of the Mott T^(-1/4) exponential with another one like a simply thermally activation process. It fits well several experimental results reported as having a crossover between the Efros-Shklovskii and Mott regimes, and allows the determination of the gap parameters even in experiments that do not reach the T^(-1/2) regime. Also it accounts for some experimental results reported to follow a T^(-n) behavior with 0.5<n<1.