Generation of fully spin-polarized currents in three-terminal graphene-based transistors

摘要

We propose three-terminal spin devices with graphene nanoribbons (terminals)and a graphene flake (channel) to generate a highly spin-polarized currentwithout an external magnetic field or ferromagnetic electrodes. The Hubbardrepulsion within the mean-field approximation plays the main role to separatethe unpolarized electric current at the source terminal into spin-polarizedcurrents at the drain terminals. It is shown that by modulating one of thedrain voltages, a fully spin-polarized current can be generated in the otherdrain terminal. In addition, the geometry of the channel and the arrangement ofedge atoms have significant impact on the efficiency of spin currents in thethree-terminal junctions which might be utilized in generation ofgraphene-based spin transistors.