Symmetric and antisymmetric electric fields induced spin valves in a zigzag silicene nanoribbon ferromagnetic...

We report a possible two dimensional spin switch based on an even-chain zigzag silicene nanoribbon (ZSR) ferromagnetic junction with two perpendicular staggered electric fields. By calculating the transverse conductance of the device, we find that the metal-insulator phase transition could always occur in the system regardless of two staggered electric fields are symmetric or antisymmetric along the y -axis of the ribbon, which can act as an electrical tunable spin valve to filter and detect one species of spin state. When two symmetric staggered electric fields are applied, both spin up and spin down electrons are prohibited to transport in the same energy region due to the energy gap opened by the homogeneous staggered potentials, which is independent of whether two electric fields are fully or partially distributed. When two staggered electric fields are anti-symmetrically put on the ZSR junction, it has the same energy band symmetry(pseudo-parity) as the pristine ZSR without applying the electric field, the energy band selection rule appears and can be used to generate, separate and detect 100% polarized spin currents combined with the staggered potential. Our findings may provide a possible way to design an electrical controllable spin switch in two dimensional graphene-like materials.