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

We measured the conductance fluctuation of bi- and trilayer graphene devices prepared on mechanical exfoliated graphene by an all-dry, lithography-free process 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 suppressed quickly from a value consistent with universal conductance fluctuation when the devices were still well within weakly disordered regime. The possible physical origins of the suppression are discussed.