Effect of charged impurity correlation on transport in monolayer and bilayer graphene

TL;DR

This paper investigates how correlations among charged impurities affect the electrical conductivity in monolayer and bilayer graphene, explaining experimental observations without invoking additional scattering mechanisms.

Contribution

It introduces the role of impurity correlation effects in Coulomb disorder as a key factor influencing graphene transport properties.

Findings

Impurity correlations explain sublinear conductivity scaling in graphene.

Correlations induce a crossover in conductivity scaling at higher densities.

Conductivity can increase with impurity density due to correlations.

Abstract

We study both monolayer and bilayer graphene transport properties taking into account the presence of correlations in the spatial distribution of charged impurities. In particular we find that the experimentally observed sublinear scaling of the graphene conductivity can be naturally explained as arising from impurity correlation effects in the Coulomb disorder, with no need to assume the presence of short-range scattering centers in addition to charged impurities. We find that also in bilayer graphene correlations among impurities induce a crossover of the scaling of the conductivity at higher carrier densities. We show that in the presence of correlation among charged impurities the conductivity depends nonlinearly on the impurity density $n_i$ and can even increase with $n_i$.