Temperature dependence of the conductivity of ballistic graphene

TL;DR

This paper studies how the electrical conductivity of ballistic graphene varies with temperature and density, revealing linear and square-root dependencies and non-monotonic behavior, aligning with experimental observations.

Contribution

It provides a theoretical analysis of temperature-dependent conductivity in ballistic graphene using Landauer transport theory, highlighting new non-monotonic features and oscillations.

Findings

Conductivity grows linearly with temperature at high T and low density.

At high density, conductivity scales as |n|^1/2 with negative T corrections.

Conductivity exhibits a non-monotonic dependence on T and n, with a minimum at a specific T.

Abstract

We investigate the temperature dependence of the conductivity in ballistic graphene using Landauer transport theory. We obtain results which are qualitatively in agreement with many features recently observed in transport measurements on high mobility suspended graphene. The conductivity \sigma at high temperature T and low density n grows linearly with T, while at high n we find \sigma ~ |n|^1/2 with negative corrections at small T due to the T-dependence of the chemical potential. At moderate densities the conductivity is a non-monotonic function of T and n, exhibiting a minimum at T=0.693 \hbar v |n|^1/2 where v is the Fermi velocity. We discuss two kinds of Fabry-Perot oscillations in short nanoribbons and their stability at finite temperatures.