Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: Transport - Poster Session

TT 28.42: Poster

Donnerstag, 29. März 2007, 14:00–17:45, Poster A

Influence of spin waves on the transport through a quantum-dot spin valve — •Björn Sothmann¹, Jürgen König¹, and Anatoli Kadigrobov^1,2 — ¹Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum — ²Department of Physics, Göteborg University, SE-412 96 Göteborg

We study transport through a quantum-dot spin valve, i.e. a single-level quantum dot with strong Coulomb interaction weakly coupled to ferromagnetic leads with non-collinear magnetizations. When a bias voltage is applied, a spin is accumulated on the dot leading to a reduction of the conductance. The Coloumb interaction leads to a spin precession which can be described in terms of an exchange field. In the linear transport regime this exchange field gives rise to a reduction of the spin-valve effect while in the non-linear regime it yields a negative differential conductance.

In Ref. [1] a real-time diagrammatic technique was developed to describe transport through quantum-dot spin valves. We extend this theory by taking into account the effect of spin waves induced in the leads. We deduce kinetic equations for the dot’s occupation, its spin and the number of excited spin waves. These are used to compute the transport properties in the linear and non-linear transport regime.

[1] M. Braun, J. König, J. Martinek, Phys. Rev. B 70, 195345 (2004)