Regensburg 2000 – scientific programme
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HL: Halbleiterphysik
HL 5: Quantenpunkte und Quantendr
ähte: Theorie
HL 5.10: Talk
Monday, March 27, 2000, 12:45–13:00, H15
Orbital and spin Kondo effects in a capacitively-coupled double-dot system — •T. Pohjola1,2, H. Schoeller3, D. Boese2, and G. Schön2 — 1Materials Physics Laboratory, Helsinki University of Technology, Finland — 2Institut für Theoretische Festkörperphysik, Universität Karlsruhe, Germany — 3Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Germany
We study electron transport through a capacitively-coupled double quantum dot with large level spacing and charging energy. Motivated by recent experiments [1] we focus on linear and nonlinear response of one of the two dots and in the presence of strong Coulomb interaction between the dots. At low temperature and strong coupling to the leads, quantum fluctuations and Kondo-like many-body effects become important and show up, e.g., as resonances in the current-voltage characteristics. The details of the resonant structures depend on both orbital and spin degeneracies in the system. In the spin-degenerate case, also single dots display the Kondo effect as a zero-bias anomaly in the nonlinear conductance. [2] In the present model, a similar effect may be found due to orbital degeneracy of the states in different dots and this also in the absence of spin degeneracy. In particular, we propose a way to observe the splitting of the Kondo peak as a function of the applied bias voltage.
[1] U. Wilhelm et al., proceedings of EP2DS, Ottawa, (1999); Physica E.
[2] D. Goldhaber-Gordon et al., Nature (London), 391, 156 (1998); S.M. Cronenwett et al., Science 281, 540 (1998).