Spin-dependent bandgap structures and spin filtering in graphene with multiple ferromagnetic barriers

Motivated by the experimental isolation of graphene [1], intense investigations have been paid the physical properties of the two-dimensional (2D) honeycomb lattice. Graphene is regarded as a promising material for spintronic applications due to its weak spin-orbit coupling and long spin lifetimes [2]. Up to now, several groups have studied the spin transport properties in graphene with magnetic and electrostatic modulation potentials [3]. How to get efficient spin filtering is one of the research focuses for the application of spintronics. In this work, we investigate spin-dependent bandgap structures and spin filtering in graphene with multiple ferromagnetic barriers. It is shown that the spin-up and spin-down electrons possess different bandgap structures in the case of oblique incidence. As a result, full spin polarization can be achieved within several separated energy intervals. The width of the energy interval with full spin polarization can be effectively manipulated by adjusting the strength of the exchange field. Correspondingly, conductance steps with full spin polarization are observed in the systems. Our investigations may have potential applications in the design of carbon-based spin filters.