Charge transport in ballistic multiprobe graphene structures

Abstract

We study the transport properties of multiterminal ballistic graphene samples concentrating on the conductance matrix, fluctuations, and cross correlations. Far away from the Dirac point, the current is carried mostly by propagating modes and the results can be explained with the conventional semiclassical picture familiar from ray optics, where electrons propagate along a single direction before scattering or reaching the terminals. However, close to the Dirac point the transport is due to evanescent modes which do not have to follow a rectilinear path. As we show in this paper, this property of the evanescent modes influences the conductance matrix. However, at best it can be observed by measuring the cross correlations in an exchange Hanbury Brown-Twiss experiment.