Signatures of evanescent mode transport in graphene

Abstract

We calculate the shot noise generated by evanescent modes in graphene for several experimental setups. For two impurity-free graphene strips kept at the Dirac point by gate potentials, separated by a long highly doped region, we find that the Fano factor takes the universal value F = 1/4. For a large superlattice consisting of many strips gated to the Dirac point interspersed among doped regions, we find F = 1/(8 ln 2). These results differ from the value F = 1/3 predicted for a disordered metal, providing an unambiguous experimental signature of evanescent mode transport in graphene.