Spin filter and spin-polarized electric current in silicene nanoribbons induced by point defects

Half-metals, in which one spin channel is conductive but the other one is insulating or semiconducting, is the key ingredient to achieve spin-polarized currents. Hybrid structures of 2D materials and ferromagnetic insulators, like EuO, provide a route to induce half-metallicity and pave the way for spintronic applications. The ferromagnetic insulator induces a proximity exchange interaction between the spins in the material that results in a spin modulation of the structures. In this context, in this work we address the effects of a random distribution of adatoms on the electron transport properties of silicene nanoribbons. The tunnel coupling between adatoms and silicon atoms induces an electronic Fano effect that makes the conductance vanish when the Fermi level matches the resonant energy induced by the adatoms. The resonant energy is independent of the random distribution of adatoms, provided that they do not cluster. When the nanoribbon is in close proximity to a ferromagnetic insulator, the resonant energy depends on the electron spin and consequently the electric current can be highly spin polarized. Our results expand the base of available materials to designing a tunable source of polarized electrons for spintronics.