▎ 摘　　要

We have investigated the effect of surface oxidation on the transport properties in graphene-Co and -Ni junctions by introducing oxygen atoms between graphene and metal surfaces using the density functional theory and the nonequilibrium Green's function method. When O atoms are intercalated between graphene and metal surfaces, graphene is physisorbed on Ni and Co surfaces while it is chemisorbed on the pristine Ni and Co surfaces. Then, the linear dispersion survives and the injection of electron from the metal electrodes into graphene is prohibited. Our results suggest that the good contacts of metal electrodes to graphene are significant role on the reduction of contact resistance. (C) 2014 The Japan Society of Applied Physics