Diffusive transport in graphene: the role of interband correlation

TL;DR

This paper investigates how interband correlations affect the diffusive transport and conductivity in graphene, revealing a minimum conductivity at a critical electron density and analyzing the impact of different scattering potentials.

Contribution

It introduces a kinetic equation approach that incorporates interband correlation effects into the analysis of graphene's dc transport properties.

Findings

Conductivity includes an anomalous term linear in impurity density.

A minimum in conductivity occurs at a critical electron density $N_c$.

Minimum conductivity is about $5.1 e^2/h$ for typical parameters.

Abstract

We present a kinetic equation approach to investigate dc transport properties of graphene in the diffusive regime considering long-range electron-impurity scattering. In our study, the effects of interband correlation (or polarization) on conductivity are taken into account. We find that the conductivity contains not only the usual term inversely proportional to impurity density $N_i$, but also an anomalous term that is linear in $N_i$. This leads to a minimum in the density dependence of conductivity when the electron density $N_{\rm e}$ is equal to a critical value, $N_c$. For $N_{\rm e}>N_c$ the conductivity varies almost linearly with the electron density, while it is approximately inversely proportional to $N_{\rm e}$ when $N_{\rm e}<N_c$ in the diffusive regime. The effects of various scattering potentials on the conductivity minimum are also analyzed. Using typical experimental parameters, we find that for RPA screened electron-impurity scattering the minimum conductivity is about $5.1 e^2/h$ when $N_{\rm e}\approx 0.32N_i$.