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TT: Fachverband Tiefe Temperaturen

TT 35: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3

TT 35.16: Vortrag

Donnerstag, 28. Februar 2008, 18:15–18:30, H 3010

Violation of Wiedemann-Franz Law in a Single-Electron Transistor — •Björn Kubala^1,2, Jürgen König¹, and Jukka Pekola³ — ¹TP III, Ruhr-Universität Bochum, 44780 Bochum, Germany — ²Physics Department, ASC, and CeNS, Ludwig-Maximilians-Universität, 80333 Munich, Germany — ³Low Temperature Laboratory, Helsinki University of Technology, PO BOX 3500, 02015 TKK, Finland

We study the influence of Coulomb interaction on the thermoelectric transport coefficients for a metallic single-electron transistor [1]. By performing a perturbation expansion up to second order in the tunnel-barrier conductance, we include sequential and cotunneling processes as well as quantum fluctuations that renormalize the charging energy and the tunnel conductance. We find that Coulomb interaction leads to a strong violation of the Wiedemann-Franz law: the Lorenz ratio becomes gate-voltage dependent for sequential tunneling, and is increased by a factor 9/5 in the cotunneling regime. Finally, we suggest a measurement scheme for an experimental realization.

[1] B. Kubala, J. König, and J. Pekola, arXiv:0709.4181 (unpublished).