title: Nonlinear spin current and magnetoresistance of molecular tunnel junctions.
abstract: We report on a theoretical study of spin-polarized quantum transport through a Ni-bezenedithiol(BDT)-Ni molecular magnetic tunnel junction (MTJ). Our study is based on carrying out density functional theory within the Keldysh nonequilibrium Green's function formalism, so that microscopic details of the molecular MTJ are taken into account from first principles. A magnetoresistance ratio of approximately 27% is found for the Ni-BDT-Ni MTJ which declines toward zero as bias voltage is increased. The spin currents are nonlinear functions of bias voltage, even changing sign at certain voltages due to specific features of the coupling between molecular states and magnetic leads.
authors.affiliation: Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, PQ, H3A 2T8, Canada.
authors.forename: Derek
authors.initials: D
authors.lastname: Waldron
authors.forename: Paul
authors.initials: P
authors.lastname: Haney
authors.forename: Brian
authors.initials: B
authors.lastname: Larade
authors.forename: Allan
authors.initials: A
authors.lastname: MacDonald
authors.forename: Hong
authors.initials: H
authors.lastname: Guo