Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Poster Session Transport & Matter at Low Temperature

TT 58.12: Poster

Donnerstag, 14. März 2013, 15:00–19:00, Poster D

Non-equilibrium quantum dynamics of the magnetic Anderson model — •Daniel Becker^1,2, Stephan Weiss³, Michael Thorwart¹, and Daniela Pfannkuche¹ — ¹I. Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg — ²Department Physik, Universität Basel, 4056 Basel, Schweiz — ³Theoretische Physik, Universität Duisburg-Essen and CENIDE, 47048 Duisburg, Germany

For a Coulomb-interacting single-level quantum dot in contact with two metallic leads and a spin-1/2 magnetic impurity, which is exchange-coupled to the electron spin, a systematical investigation of the mutual dependencies between charge current and impurity relaxation dynamics is provided. To this end, the numerically exact, non-perturbative scheme of iterative summation of path integrals (ISPI)[1] is employed in a regime, where all appearing energy scales are of the same order of magnitude. We observe a significant influence of the non-equilibrium decay of the impurity spin polarization both in the presence and absence of Coulomb interaction. The exponential relaxation is faster for larger bias voltages, electron-impurity interactions and temperatures. Conversely, we find a reduction of the stationary current for increasing coupling to the impurity. Moreover, our approach allows us to systematically distinguish mean-field Coulomb and impurity effects from the influence of quantum fluctuations and flip-flop scattering, respectively. In fact, we find a local maximum of the current for a finite Coulomb interaction due to the presence of the impurity.
[1] D. Becker et al., NJP 14, 073049 (2012)