Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.21: Poster

Friday, March 4, 2005, 14:00–18:00, Poster TU C

Spin-dependent transport through quantum dots with three ferromagnetic leads — •Daniel Urban, Matthias Braun, and Jürgen König — Institut für Theoretische Physik III, Ruhr-Universität Bochum

We examine a single-level quantum dot weakly tunnel-coupled to three ferromagnetic leads. A current between two leads gives rise to spin accumulation and spin blockade. Two effects allow to modify the spin on the dot by changing the magnetization direction of the floating third lead.

The first of these effects is anisotropic spin damping. Spin components in the direction of the third lead have an increased lifetime. The second is an exchange field arising in the presence of ferromagnetism and Coulomb interaction [1]. It causes precession of the accumulated spin [2].

Transport through the system depends on the spin on the dot and can thus be controlled by the third lead in a transistor-like manner.

[1] J. König and J. Martinek, Phys. Rev. Lett. 90, 16 (2002).

[2] M. Braun and J. König and and J. Martinek, to appear in Phys. Rev. B, (2004), cond-mat/0404455.