Efficient Dual Spin-Valley Filter In Strained Silicene

We propose a highly efficient silicene device for dual spin and valley filtering. The device consists of two different barrier regions: the first is a region under uniaxial strain, with an exchange field induced by adjacent top and bottom magnetic insulators, while the second comprises of two ferromagnetic stripes which produces a delta-function fringe magnetic field, and a gate electrode to modify the electrochemical potential. For the first region, we investigated the effect of the uniaxial strain in inducing angular separation of the two valley spins in momentum-space, and further spin separation by the spin dependent electric potential induced by the exchange field. We then evaluated the delta-function magnetic field and electrochemical potential combination in the second region to yield the transverse displacement for the selection of the requisite spin-valley combination. We demonstrated the optimal conditions in the first barrier to induce a highly anisotropic transmission profile, which enables controllable and efficient filtering (> 90% efficiency) by the second region for all four spin-valley combinations. Based on the analytical results, we predict the feasibility of experimental realization of dual spin-valley silicene-based filtering device.