Universal temperature dependence of the conductivity of a strongly disordered granular metal

TL;DR

This paper demonstrates that in strongly disordered granular metals, the temperature dependence of conductivity follows a universal nonlinear function determined solely by the system's dimensionality, regardless of microscopic details.

Contribution

It introduces a universal description of conductivity temperature dependence in strongly disordered granular metals using a renormalization group approach.

Findings

Universal nonlinear temperature dependence in 2D granular metals

Dependence solely on system dimensionality in strong disorder regime

Dimensional crossover effects in granular films

Abstract

A disordered array of metal grains with large and random intergrain conductances is studied within the one-loop accuracy renormalization group approach. While at low level of disorder the dependence of conductivity on log T is nonuniversal (it depends on details of the array's geometry), for strong disorder this dependence is described by a universal nonlinear function, which depends only on the array's dimensionality. In two dimensions this function is found numerically. The dimensional crossover in granular films is discussed.