Perfect spin polarization, valley polarization, and tunneling magnetoresistance in bilayer silicene magnetic superlattices

We have theoretically investigated the spin- and valley-dependent transport in the bilayer silicene magnetic superlattices consisting of alternatively ferromagnetic and nonmagnetic domain. The calculation with a four-band scattering matrix method demonstrates that due to the spin- and valley-resolved band splitting in the field-tunable ferromagnetic domains, perfect spin and valley polarization can be engineered for the symmetric superlattice only in its parallel magnetization configuration, while for the asymmetric superlattice, it can be engineered in both the parallel and antiparallel magnetization configurations. For both types of superlattice, a strong contrast in the configuration-dependent conductance makes a field-controllable, yet colossal tunneling magnetoresistance accessible. These features indicate that a bilayer silicene magnetic superlattice might be a potential choice for silicene-based spin-valleytronic applications.