Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Quantum Dots, Quantum Wires, Point Contacts

TT 22.2: Vortrag

Dienstag, 17. März 2020, 09:45–10:00, HSZ 201

Asymmetry effects and spin dynamics in resonant transport through quantum-dot spin valves — •Simon Mundinar, Alfred Hucht, Jürgen König, and Stephan Weiss — Theoretische Physik, Universität Duisburg-Essen and CENIDE, Lotharstr. 1, 47048 Duisburg, Germany

We present results of a theoretical investigation of spin effects in resonant transport through an interacting quantum-dot spin valve. The system is built from a quantum dot tunnel-coupled to two ferromagnetic leads, that induce spin-dependent tunneling. In the regime of small to intermediate interaction strengths we study the current through the system as well as occupation number and spin components of the dot, using the method of iterative summation of path integrals (ISPI) to achieve numerical exact data. We find an asymmetry in the current with respect to the gate voltage, that manifests once a local Zeeman field is applied to the quantum dot. The asymmetry can be traced back to the spin-dependent hybridization between dot and leads, together with higher order exchange field effects. Additionaly, we report on the strong impact of resonant tunneling processes on the tunnel magnetoresistance (TMR) at low temperatures [1]. We find a strong response of the TMR to an externally applied Zeeman field, resulting in a change in the sign of the TMR.

[1] S. Mundinar, P. Stegmann, J. König, S. Weiss, Phys. Rev. B 99, 195457 (2019)

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