Tunneling conductance spectrum of graphene ferromagnet-insulator-superconductor junctions

Starting with the mean field Dirac-Bogoliubov-de-Gennes model and the Bolonder-Tinkham-Klapwijk formalism, we study the transport properties of a graphene ferromagnet-insulator-superconductor junction by taking into account the effect of the finite width of the insulating region. The tunneling conductance oscillations as a function of the bias energy are revealed together with a non-monotonic behavior for the exchange field in the ferromagnet layer. These phenomena, which are quite different from those in the conventional counterparts, are understood by examining the electron scattering processes associated with the unique dispersion-relation of the graphene junctions.