Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 64: Poster Session: Transport

TT 64.1: Poster

Donnerstag, 4. April 2019, 15:00–18:30, Poster D

Spin effects in resonant transport through interacting quantum dots — •Simon Mundinar, Jürgen König, and Stephan Weiss — Theoretische Physik, Universität Duisburg-Essen and CENIDE, 47048 Duisburg, Germany

We report on numerically exact iterative path-integral calculations (ISPI) for spin-dependent transport through small interacting quantum dots [1-3]. Our ISPI method builds upon the truncation of exponentially vanishing real-time correlations at finite temperature and/or bias voltage. In particular, we study two distinct systems (i) a spin-valve, where ferromagnetic leads induce spin-dependent tunnel couplings between leads and dot [2] and (ii) a hybrid structure, where the quantum dot is coupled to a normal and a superconducting lead [3]. For the spin-valve setup, the observable of interest is the tunneling magnetoresistance through the quantum dot, which is investigated for various system parameters. We find that, especially at low temperatures, resonant tunneling effects are dominant and the sequential picture does not apply. The role of Coulomb interactions together with changing the temperature of the system is explored. Within the hybrid system, a finite gap parameter Δ induces anomalous self energies in the Keldysh partition function. ISPI calculations are performed to deduce, e.g. the impact of Coulomb interactions on the Andreev bound state spectrum in a nonequilibrium situation.
[1] S. Weiss, et. al, Phys. Status Solidi B, 250 (11), 2298-2314 (2013).
[2] S. Mundinar, J. König, and S. Weiss, in preparation (2018).
[3] S. Weiss and J. König, in preparation (2018).