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HL: Halbleiterphysik

HL 44: Poster II

HL 44.31: Poster

Donnerstag, 11. März 2004, 16:30–19:00, Poster A

Thermoelectrical properties of single quantum dots — •Ralf Scheibner, Hartmut Buhmann, and Laurens W. Molenkamp — Experimentelle Physik III, Universität Würzburg

We analyze the thermoelectrical properties of lateral single quantum dots in the coulomb blockade regime. For measuring the thermopower it is necessary to apply a temperature gradient across the device. This is achieved by an electron gas heating technique. The ability to tune the temperature of the whole system and the coupling of the quantum dot to the leads allows us to investigate the sequential, the cotunneling as well as the Kondo regime. Temperature dependent measurements show a crossover between the sequential and the cotunneling regime that we compare with the calculations from [1]. In the Kondo regime the comparison of conductance and thermopower measurements shows deviations from Mott’s law suggesting a possible contribution of the electronic spin entropy to the total entropy current that is the likely source of enhanced thermopower in Co oxides [2].

[1] M.Turek and K.A. Matveev, ArXiv: cond-mat/ 0112445.

[2] Y. Wang, et.al., Nature, 423, 425, (2003).