Spin filter effects in zigzag-edge graphene nanoribbons with symmetric and asymmetric edge hydrogenations

Using the non-equilibrium Green's function method combined with the density functional theory, we investigate the magnetism and spin-dependent transport properties of symmetric and asymmetric zigzag-edged graphene nanoribbons (ZGNRs) passivated by monohydrogenation with [1, −1] magnetism configuration. The symmetric model H-6ZGNR-H shows a dual spin filter effect, but asymmetric H-5ZGNR-H behaves as a conductor with linear current-voltage relationships. We also investigate the magnetism and spin-dependent transport properties of H2-ZGNR-H with asymmetric edge hydrogenations, the perfect dual spin filtering effect is observed in both H2-5ZGNR-H and H2-6ZGNR-H. The transmission pathways and PDOS demonstrate that the edge of C-H2 bonds have important effects on the magnetism and spin-dependent transport properties as compared with the edge of C-H bonds.