Gate tunable graphene break junction spin filter

Graphene has attracted great interest for application in spintronics due to its intrinsic low spin-orbital and hyperflne interaction. The graphene spin filter, which permits the transport of electrons with certain spin only, has been used to realize electron spin-based logic devices. The spin polarity of a spin filter has strong correlation with the parallel or anti-parallel magnetic alignment of its electrodes. In this study, we theoretically investigate the effect on spin transport, of applying a voltage to a gate of a break junction based spin filter using density functional theory (DFT) combined with non-equilibrium green's function (NEGF). Our results indicate that an applied voltage to an electric gate induces an interference effect on the spin scattering states, which can be used to control the spin filtering polarity. This result indicates that a gate tunable spin filter is possible, which may unleash exciting opportunities for future spintronic circuits and systems.