Site-dependent spin-polarized tunneling via hybrid interface states on molecule/ferromagnet surface

Based on density functional theory and nonequilibrium Green's function method, we investigate the spin polarization and transport ability of hybrid interface states at benzene/Ni surface by introducing the top probe electrode. The results demonstrate that when the top electrode connects the molecule with different sites, the spin polarization of the projected density of states and the interfacial spin density distribution are disturbed in different ways. A contact site induced inversion of the spin polarization is observed at Fermi energy. The transport calculation indicates that the center contact is better to achieve a large tunneling magnetoresistance at low bias, but the edge and top contacts is useful to get a little larger spin polarization of the current. This work points out that the spin polarization and transport property of the hybrid interface states in a molecular junction depends on the way to introduce the second probe electrode, which can be suitable designed to achieve an excellent performance.