Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 23: Nanoelektronik II: Spin-Elektronik
TT 23.3: Vortrag
Mittwoch, 10. März 2004, 18:00–18:15, H19
Spin-dependent transport through quantum dots attached to ferromagnetic leads — •Jürgen König1,2, Jan Martinek1, and Gerd Schön1 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe — 2Institut für Theoretische Physik III, Ruhr-Universität Bochum
We study spin-dependent transport through quantum dots coupled to
ferromagnetic
leads. First, we consider strong dot-lead coupling and analyze how the
spin polarization of the leads affects the Kondo effect.
Based on a scaling approach we predict [1] that an effective Zeeman
splitting
and hence a splitting of the zero-bias anomaly is induced.
With an additional magnetic field, this splitting can be
compensated, and the strong-coupling limit of the Kondo effect
is recovered.
These results are backed up by rigorous numerical-renormalization-group
calculations [2].
Second, weak dot-lead coupling is considered.
We determine the linear conductance as a function of the relative angle
between
the leads’ magnetization directions [3].
An interaction-induced rotation of the quantum-dot spin is found, which
yields a reduction of the spin-valve effect.
[1] J. Martinek et al., Phys. Rev. Lett. 91, 127203
(2003).
[2] J. Martinek, M. Sindel, L. Borda, J. Barnas, J. König,
G. Schön, and J. v. Delft, accepted for Phys. Rev. Lett.
[3] J. König and J. Martinek, Phys. Rev. Lett. 90,
166602 (2003).