title: Violation of the Wiedemann-Franz law in a single-electron transistor.
abstract: We study the influence of Coulomb interaction on the thermoelectric transport coefficients for a metallic single-electron transistor. 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.
authors: Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors: Björn
authors: B
authors: Kubala
authors: Jürgen
authors: J
authors: König
authors: Jukka
authors: J
authors: Pekola