Controllable photo-induced spin and valley filtering in silicene

We investigate theoretically the spin- and valley-dependent ballistic transport in silicene, which is assumed to be modulated by local application of a gate voltage and off-resonant circularly polarized light. We show that, due to the coupling between valley and spin degrees of freedom in silicene, the current through it is spin and valley polarized. The spin (valley) polarization can be enhanced by tuning the light intensity and the value of the perpendicular electric field, leading to perfect spin (valley) filtering for certain of their values. It is also found that the spin (valley) polarization can be inverted by reversing the perpendicular electric field (by reversing the perpendicular electric field or reversing the circular polarization of the light irradiation).