Controllable spin-polarization using external electric field and spin-inversion in a silicene quantum dot

It is shown that, for appropriate values of electron energy, the silicene dot can work as a controllable spin polarizer. The spin polarizer can polarize the spin of transmitted electrons from nearly pure down to nearly pure up by changing the strength of an external electric field. Also, for spin polarized incoming electrons, the silicene quantum dot can invert the spin of electrons and can works as a spin inverter or a spin NOT gate. In addition, we investigate the effects of exchange field, induced by ferromagnetic substrate, on electron conductance and show that the silicene quantum dot can act as a nearly perfect spin-filter in the presence of exchange field.