Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 46: Quantum Dots, Quantum Wires, Point Contacts

TT 46.9: Vortrag

Mittwoch, 3. April 2019, 17:15–17:30, H22

Resonant tunneling through interacting quantum-dot spin valves - ISPI results — •Simon Mundinar, Jürgen König, and Stephan Weiss — Theoretische Physik, Universität Duisburg-Essen and CENIDE, Lotharstr. 1, 47048 Duisburg

We study an interacting quantum dot coupled resonantly to ferromagnetic leads that induce spin-dependent tunneling. Starting with a real-time path integral approach expectation values of interest in the stationary limit are obtained from functional derivatives of the Keldysh partition function. Interactions are decoupled via a Hubbard-Stratonovich transformation which results in a discrete spin trace along the Keldysh contour. This trace is performed by means of iterative summation of path integrals (ISPI) [1], which is based on the truncation of lead-induced correlations after a characteristic memory time. Within this scheme we explore current-based observables and the density matrix for different system parameters, such as temperature, gate/bias voltage, polarization and Coulomb interaction strength. We tune parameters of interest beyond the perturbative regime. Especially in the low-temperature regime we find a strong impact of resonant tunneling processes on transport properties through quantum dot, leading to a rich structure in the tunnel magnetoresistance.
S. Weiss, R. Hützen, D. Becker, J. Eckel, R. Egger, and M. Thorwart, Phys. Status Solidi B 250, 2298-2314 (2013)
S. Mundinar, J. König, S. Weiss in preperation