Gate-controlled spin and valley polarization transport in a ferromagnetic/nonmagnetic/ferromagnetic silicene junction

We study spin and valley transport through a ferromagnetic/nonmagnetic/ferromagnetic (FNF) monolayer silicene junction in the presence of an electrostatic gate potential U and on-site potential difference Δz in the nonmagnetic region. We theoretically demonstrate that away from the band gap (no spin and valley conductances), the spin and valley polarizations of the junction show an oscillatory behaviour with U but near to it, they almost show a linear dependence with U. These oscillations are due to the phase difference of the electron wavefunctions of the spin and valley-resolved conductances that lead to chiral nature of the quasi-bound states in silicene. In particular, we find that the amplitude and frequency of the spin and valley polarizations oscillations of the junction can be tuned by varying the electrostatic gate potential U and on-site potential difference Δz. Furthermore, it is shown that by increasing the exchange energy h the amplitudes of the spin and valley polarizations oscillations suppress. Enhanced spin (valley) polarization and its control by means of the electrostatic gate potential U makes the nonmagnetic tunneling junction a suitable candidate for utilizing in valleytronics and spintronics applications.