Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 18: Nanoelectronics I - Quantum Dots, Wires, Point Contacts
TT 18.2: Talk
Wednesday, March 28, 2007, 14:15–14:30, H19
Co-tunneling effects in transport through interacting quantum dots — •Jasmin Aghassi1,2, Matthias Hettler1, and Gerd Schön1,2 — 1Forschungszentrum Karlsruhe, INT, Postfach 3640, 76201 Karlsruhe — 2Institut für theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe
We study charge transport in quantum dot systems within a diagrammatic
technique. The current-voltage characteristics as well as the current noise
are calculated within second-order perturbation expansion in the coupling
parameter Γ. We allow for an intermediate coupling regime up to coupling
constants of Γ=kB T, where kB is the Boltzmann constant and T the
temperature. We explicitly account for intra- and inter-dot Coulomb
interactions and the resulting many-body states of the quantum dots.
For a single multilevel quantum dot we investigate the
co-tunneling effects on the conductance and noise of the system in dependence
of an applied gate voltage. In the Coulomb blockade region super-Poissonian noise is
observed at the inelastic co-tunneling energy scale. This energy
scale is also observable in the conductance in some cases.
For non-local systems such as chains of coupled quantum dots (“artificial
molecules”) sequential tunneling results for transport under asymmetric
conditions, i.e. non-resonant dots or asymmetric couplings are compared to second order results.
A. Thielmann et.al., Phys. Rev. Lett., 95, 146806 (2005)
J. Aghassi et.al, Appl. Phys. Lett. 89, 052101 (2006), Phys. Rev.B
73, 195323 (2006)