Spin polarisation using gate voltage through a Rashba barrier in graphene

Abstract

Gate-tunable spin-resolved scattering through a Rashba spin–orbit (SO) coupling graphene barrier is considered theoretically by using a mode-matching method. In this structure, we investigate the dependence of the tunnelling transmission probability on the spin orientation of the incident electron. It is found that the difference of the transmission probability for opposite spin orientations exhibits considerable incident-angle-dependent features when both gate voltage and Rashba SO coupling in the barrier region are present. The difference is adjustable by the gate voltage. More specifically, we find that the sign of spin polarisation of conductance can switch from positive to negative by adjusting the electric potential at any Rashba SO coupling. These results can provide an efficient way to design graphene spintronic devices without the need for ferromagnets.