MAGNETO-OSCILLATION PHASE ANOMALIES IN BIASED GRAPHENE BILAYERS

Magneto-oscillation (MO) properties, the periodicity and phase, of graphene bilayers are discussed. Using a four-band continuum model [1,2], we calculated analytically the Landau plots in unbiased and biased graphene bilayers subject to perpendicular magnetic fields for a variety of carrier concentrations and bias strengthes between graphene planes. We showed that MOs are aperiodic for both unbiased and biased bilayers, their phases are variables which depend on the Landau level index. MOs are only asymptotically periodic, and in the unbiased bilayer the MO phase follows the quasiclassical prediction 1/2. Anomalous behavior of MO phases was found in biased bilayers with broken inversion symmetry [3]. The oscillation frequencies tend to quasiclassically predicted ones, which are the same for K and K’, but the quantum approach yields the gate-tunable corrections to oscillation phases, which differ in sign for K and K’. These valley-dependent phase corrections give rise, instead of a single quasiclassical series of oscillations, to two series with the same frequency but shifted in