Electron spin inversion in gated silicene nanoribbons

We study locally gated silicene nanoribbons as spin active devices. We find that the gated segments of nanoribbons with zigzag edge can be used to perform a spin inversion for the electron spins injected with an in-plane orientation. The strong intrinsic spin-orbit coupling for low Fermi energy in presence of an external vertical electric field provides a fast spin precession around the axis perpendicular to the silicene plane. The spin inversion length can be as small as 10 nm. On the other hand in the armchair nanoribbons the spin inversion occurs via the Rashba effect which is weak and the spin inversion lengths are of the order of $\mu$m.