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TT: Tiefe Temperaturen

TT 5: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts - Part 1

TT 5.3: Vortrag

Montag, 27. März 2006, 10:15–10:30, HSZ 304

Cotunneling and renormalization effects in the thermopower of a single-electron transistor — •Björn Kubala and Jürgen König — Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum, Germany

We study thermal conductance and thermopower of a metallic single-electron transistor (SET) within a perturbative real-time theory. Like the conductance, the thermal conductance of an SET is governed by Coulomb blockade physics at low temperatures. The (Coulomb-) oscillations of thermopower with varying gate voltage have been studied, considering sequential [1] and cotunneling [2] processes.

We investigate thermopower by performing a systematic perturbative calculation of the (thermal) conductance including sequential tunneling and cotunneling as well as terms capturing the renormalization of system parameters by quantum fluctuations. As thermopower constitutes a direct measure of the average energy of transported particles, we predict, that the logarithmic reduction of the Coulomb blockade gap due to a multi-channel Kondo-effect can be accessed in thermopower measurements.

[1] A. A. M. Staring, L. W. Molenkamp, B. W. Alphenhaar, H. van Houten, O. J. A. Buyk, M. A. A. Mabesoone, C. W. J. Beenakker, and C. T. Foxon, Europhys. Lett. 22, 57 (1993).

[2] M. Turek and K. A. Matveev, Phys. Rev. B 65, 115332 (2002).