Spin-polarized current and shot noise in the presence of spin flip in a quantum dot via nonequilibrium Green's functions

Fabricio De Souza, Antti-Pekka Jauho, J.C. Egues

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    Abstract

    Using nonequilibrium Green's functions we calculate the spin-polarized current and shot noise in a ferromagnet-quantum-dot-ferromagnet system. Both parallel (P) and antiparallel (AP) magnetic configurations are considered. Coulomb interaction and coherent spin flip (similar to a transverse magnetic field) are taken into account within the dot. We find that the interplay between Coulomb interaction and spin accumulation in the dot can result in a bias-dependent current polarization p. In particular, p can be suppressed in the P alignment and enhanced in the AP case depending on the bias voltage. The coherent spin flip can also result in a switch of the current polarization from the emitter to the collector lead. Interestingly, for a particular set of parameters it is possible to have a polarized current in the collector and an unpolarized current in the emitter lead. We also found a suppression of the Fano factor to values well below 0.5.
    Original languageEnglish
    JournalPhysical Review B Condensed Matter
    Volume78
    Issue number15
    Pages (from-to)155303
    ISSN0163-1829
    DOIs
    Publication statusPublished - 2008

    Bibliographical note

    Copyright 2008 American Physical Society

    Keywords

    • TRANSPORT
    • TUNNELING DEVICES
    • SCATTERING
    • MAGNETORESISTANCE
    • CONDUCTORS
    • ELECTRON-SPIN
    • LEADS

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