Regensburg 2013 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 22: Poster II
DF 22.74: Poster
Freitag, 15. März 2013, 10:30–13:30, Poster D
Cooling Nanodevices by Spin Currents — •Jochen Brüggemann1, Stephan Weiss2, Peter Nalbach1, and Michael Thorwart1 — 11. Institut für theoretische Physik, Universität Hamburg, 20355 Hamburg, Deutschland — 2Theoretische Physik, Universität Duisburg-Essen & CENIDE, 47048 Duisburg, Deutschland
In analogy to the demagnetization cooling for macroscopic devices, we aim to develop and analyze a magnetocaloric cooling cycle for nanodevices. For a proof of principle, a simple model consists of the following: First, an interacting quantum dot, which is tunnel coupled to ferromagnetic leads; second, dot electrons which can interact via exchange interaction with a localized impurity spin; and third, a Holstein phonon for the mechanical degrees of freedom. Using the real-time diagrammatic perturbation theory in lowest order in the hybridization of the leads, we determine the impurity spin dynamics as well as the mean energy of the mechanical oscillator as functions of the system parameters and the bias voltage. In agreement with previous findings, we reproduce an effective cooling of the impurity spin in the stationary limit. In the transient nonequilibrium regime, we realize a cooling cycle aiming at accumulating an increased ground state population of the phonon due to the cooling of the impurity spin as compared to the initial preparation.