Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.165: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Spin versus orbital Kondo effect in electrostatically coupled double quantum dots — •Daniel Bezecny and Alexander L. Chudnovskiy — 1. Institut für theoretische Physik, Uni Hamburg, Jungiusstr. 9, 20355 Hamburg

We consider the Kondo effect in strongly electrostatically coupled double quantum dots. The orbital structure of the electron wave function of a double dot crucially influences the transport properties if there is no energy cost to transfer an electron from one dot to the other. In that case the two degenerate states with the "last" electron either in the right or in the left dot can be associated with a spin-like degree of freedom that we call pseudo-spin. Resonant transfer of an electron correspondes to a flip of the pseudospin analogously to a spin flip in the Kondo effect. The process of a resonant pseudospin flip can induce a so called orbital (or pseudospin) Kondo effect quite similar to - and to a large extent independent of - the well-known (spin) Kondo effect. Varying the strength of the tunnel coupling between the reservoirs and each of the two dots allows a controllable change of the coupling symmetry of the Orbital Kondo effect without affecting the spin Kondo effect. Furthermore, the orbital Kondo effect can be suppressed by lifting the degeneracy of the energy levels of the left and right dot.