Valley and spin dependent group delay time in silicene superlattice

Abstract

In this paper, the valley- and spin-dependent transport properties, the tunneling time and the Hartman effect in a silicene superlattice under extrinsic Rashba spin-orbit coupling is theoretically studied. It is found that the transmission probability and the group delay time depend on the degree of freedom of the valley and spin, and that they have an oscillatory behavior with respect to the extrinsic Rashba spin-orbit interaction (ERSOI). Furthermore, the difference of the group delay time between two inequivalent valleys, and also between spin-up and spin-down can be efficiently tuned via the ERSOI strength and the number of superlattice barriers. Thus, valley-spin filtering can be achieved in the time domain in silicene superlattice with ERSOI. Especially, in contrast to the graphene superlattice, the Hartman effect or the superluminal tunneling can be observed in silicene superlattice even for the normal angle of incidence.