Suppression of conductance fluctuation in weakly disordered mesoscopic graphene samples near the charge neutral point

We measured the conductance fluctuation of bilayer and trilayer graphene devices, which were prepared on mechanically exfoliated graphene by an all-dry, lithography-free process by using an ultrathin quartz filament as a shadow mask. Reproducible fluctuations in conductance as a function of applied gate voltage or magnetic field were found. As the gate voltage was tuned so that the graphene device was pushed to the charge neutral point, the amplitude of the conductance fluctuation was found to be quickly suppressed from a value that is consistent with universal conductance fluctuation when the devices were still well within the weakly disordered regime. The possible physical origins of the suppression are discussed.