Ill-Contact Effects of d-Orbital Channels in Nanometer-Scale Conductor

Electronic current in a nanometer-size rod is theoretically investigated by an eigen-channel decomposition method in nonequilibrium Green's function formalism. Physical properties, such as the local density of electrons and local current, are decomposed into contributions of eigen-channels. We observe that the evanescent modes and nonlinear conductance are enhanced in d-orbital systems, and the structure of the transmission function, local current density, and penetration depth are discussed. The two effects of the ill-contact at electrodes in d-orbital systems, evanescent modes and the nonlinearity of conductance, are regarded as originating in the peak structure of the transmission function of eigen-channels in the energy region between chemical potentials of left and right lead wires.