Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 39: Quantenpunkte und -dr
ähte: Transporteigenschaften I
HL 39.3: Vortrag
Montag, 7. März 2005, 10:30–10:45, TU P-N202
Transport through a quantum dot spin valve — •Matthias Braun1, Jürgen König1, and Jan Martinek2 — 1Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum — 2Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe
We develop a theory of spin-dependent transport through a single-level quantum dot with strong Coulomb interaction, weakly coupled to ferromagnetic leads [1]. The theory explicitly allows for non-collinear lead magnetizations, as well as an externally-applied magnetic field.
We derive generalized rate equations for the dot’s occupation and accumulated spin and discuss the influence of the dot’s spin on the conductance of the device. The Coulomb interaction, generates an intrinsic source of spin precession, leading to negative differential conductance as well as a nontrivial dependence of the conductance on the angle between the lead magnetizations [1,2]. In addition, the applied magnetic field gives rise to the Hanle effect. We propose schemes [3] to observe these different precession mechanisms in transport experiments, and show, how to utilize them to determine the spin lifetime in the quantum dot.
[1] Matthias Braun et al., cond-mat/0404455 (2004)
[2] J. König et al., Phys. Rev. Lett. 90, 166602 (2003)
[3] Matthias Braun et al., cond-mat/0411xxx (2004)