Spin-filter effect in metallic nanowires

We present ab initio calculations for metallic nanowires with a diameter of few atoms. The electronic structure is calculated using the screened Korringa Kohn Rostoker Green's function method, while electronic transport properties are obtained using a Green's function formulation of the Landauer formalism. We focus on the effect of scattering due to transition metal impurities on the conductance of a Cu wire. For a single defect, our results show a reduction of the transmission for energies at the impurity d state and due to the spin-polarization conductance is different for the two-spin directions causing a spin-filter effect. For a defect pair, quantum interference effects lead to a complicated energy dependence of the conductance.