Spin transport in graphene spin-orbit barrier structure

► High spin polarization (∼0.85) can be obtained in a simple barrier structure without the assistance of lateral confinement and external magnetic field. ► The spin polarization can be maximized by reducing the influence between the evanescent waves in the barrier. ► The evanescent waves associated with the two interfaces can be modulated by changing thickness of the barrier and the Fermi energy. ► We show that relatively simple experimental requirement is sufficient to generate spin current in graphene.