Spin-Dependent Bandgap Structures and Spin Filtering in Graphene With Multiple Ferromagnetic Barriers

We investigate spin-dependent bandgap structures and spin filtering in graphene with multiple ferromagnetic barriers. Using the transfer matrix method, we have calculated the spin-dependent transmission coefficients, the spin polarization, the conductance, and the electronic energy spectra of the systems. It is shown that the spinup and spindown electrons possess different bandgap structures. As a result, full spin polarization can be achieved within several separated energy zones. The width of the energy zone with full spin polarization can be effectively manipulated by adjusting 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.