Aharonov Bohm effect in bilayer graphene

Dual-gated bilayer graphene is an ideal platform to study Aharonov Bohm effect with the ability to tune carrier density and electric field independently. We have fabricated ring-shaped devices and disc-shaped devices as control, with BN-encapsulated bilayer graphene and graphitic bottom and top gates. In our high quality bilayer graphene the quasi-ballistic nature of electron transport at low temperature enables us to study phase-coherent electron transport. We detect Aharonov Bohm oscillations in the ring-shaped devices where the visibility of conductance oscillations reaches 2% at high charge carrier density and temperature of 1.4K. Meanwhile, we also explore magneto-transport properties of valley currents near zero carrier density and in the presence of an external electric field. The nonlocal valley-signal shows strong magnetic field dependence. We will discuss possible mechanisms.