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

F. M. Souza, A. P. Jauho, and J. C. Egues
Phys. Rev. B 78, 155303 – Published 3 October 2008

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 . In particular, 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.

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  • Received 7 February 2008

DOI:https://doi.org/10.1103/PhysRevB.78.155303

©2008 American Physical Society

Authors & Affiliations

F. M. Souza1,2,4, A. P. Jauho2,3, and J. C. Egues4

  • 1International Center for Condensed Matter Physics, Universidade de Brasília, 70904-910, Brasília, DF, Brazil
  • 2Department of Micro and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800, Kongens Lyngby, Denmark
  • 3Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, Helsinki FI-02015 HUT, Finland
  • 4Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP, Brazil

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Vol. 78, Iss. 15 — 15 October 2008

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