Regensburg 2000 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 32: Quantenpunkte
HL 32.4: Vortrag
Donnerstag, 30. März 2000, 11:15–11:30, H15
Resonant Tunneling through Multi-level Quantum Dots — •Daniel Boese1, Teemu Pohjola1,2, Herbert Schoeller3,1, and Gerd Schön1 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe — 2Materials Physics Laboratory, Helsinki University of Technology, P.O. Box 2200, 02015 - HUT, Finland — 3Forschungszentrum Karlsruhe, Institut für Nanotechnologie, 76021 Karlsruhe
Recent progress in nanofabrication technology lead to the observation of
the
Kondo effect in semiconductor quantum dots.[1] Moreover it now becomes
feasible to tune most system parameters. Therefore we study the transport
properties of multi-level quantum dots. In particular we investigate the
non-linear conductance of a quantum dot with a non-conserved level index,
which shows signatures of an orbital Kondo model.
We approach the problem by calculating the time evolution of the density
matrix by a real time diagrammatic technique. The Keldysh formalism allows
us
to calculate quantities for finite bias voltage, i.e. out of
equilibrium. Utilizing the resonant tunneling approximation we find that
the
spectral density develops strong peaks at the Fermi edges of the
reservoirs. We
also calculate the conductance via a poor man’s scaling approach.
[1] D. Goldhaber-Gordon et al., Nature(London) 391, 156 (1998), S.M. Cronenwett et al., Science 281, 540 (1998)