Spin Polarization at Organic-Ferromagnetic Interface: E ect of Contact Con guration

Based on ab initio theory, the interfacial spin polarization of a benzene-dithiolate molecule vertically adsorbed on a nickel surface is investigated by adopting di erent microscopic con-tact con gurations. The results demonstrate a strong dependence of the interfacial spin polarization on the contact con guration, where the sign of spin polarization may vary from positive to negative with the change of contact con guration. By analyzing the projected density of states, an interfacial orbital hybridization between the 3d orbital of the nickel atom and the sp3 hybridized orbital of the sulfur atom is observed. We also simulated the interfacial adsorption in mechanically controllable break junction experiments. The magne-toresistance obtained from Julliere model is about 27% based on the calculated interfacial spin polarization, which is consistent with experimental measurement.