Spin- and valley-dependent transport properties for metal-silicene-metal junctions

Detailed knowledge relating to the interactions between silicene and normal metal is crucial to understanding silicene growth on metal surfaces and metal/silicene interfaces in nanoelectronic devices. In this work, we study the valley- and spin-dependent transport properties of a metal/silicene/metal junction (MSM) with end and side metal-silicene contacts, respectively, where the central silicene sheet is simultaneously in proximity to a ferromagnet and a perpendicular electric field. By connecting the wave amplitudes obeying the lattice Schrödinger equation for the interfaces within the tight-binding model, the tunable conductance of both end-contacted (EC) and side contacted (SC) MSM junctions have been calculated. The current through MSM junctions is spin and valley polarized due to the coupling between valley and spin degrees of freedom, and the conductance and polarization show oscillating behavior as a function of the length of the silicene sheet. In particular, we find that the full spin and valley polarized conductance can be achieved by introducing proper electric and exchange fields. Further, the conductance is heavily dependent on the hopping integrals of simple metal, silicene and metal/silicene interfaces for EC junctions, and as long as the hopping integrals satisfy certain condition (with suitable incident energy) there is no difference in the transport between EC and SC junctions. The findings here may be meaningful in understanding the nature of metal/silicene interfaces. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2015