35 research outputs found

    Tunnel Magnetoresistance of a Single-Molecule Junction

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    Based on the non-equilibrium Green's function (NEGF) technique and the Landauer-B\"{u}ttiker theory, the possibility of a molecular spin-electronic device, which consists of a single C60_{60} molecule attached to two ferromagnetic electrodes with finite cross sections, is investigated. By studying the coherent spin-dependent transport through the energy levels of the molecule, it is shown that the tunnel magnetoresistance (TMR) of the molecular junction depends on the applied voltages and the number of contact points between the device electrodes and the molecule. The TMR values more than 60% are obtained by adjusting the related parameters.Comment: 5 pages, 3 figure

    Chemical and magnetic impurity effects on electronic properties of semiconductor quantum wires

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    We present a theoretical study of electronic states in magnetic and nonmagnetic semiconductor quantum wires. The effects of chemical and magnetic disorder at paramagnetic temperatures are investigated in single-site coherent potential approximation. It is shown that the nonmagnetic impurity shifts the band of carriers and suppresses the van Hove singularities of the local density of states (LDOS) depending on the value of impurity concentration. The magnetic impurity, however, broadens the band which depends on the strength of exchange coupling, and in the high impurity concentration, the van Hove singularities in the LDOS can completely disappear and the curves become smooth.Comment: 7 pages, 6 figure