Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 1

TT 29.8: Vortrag

Donnerstag, 25. März 2010, 11:30–11:45, H19

Spin-dependent transport through quantum-dot Aharonov-Bohm interferometers — •Bastian Hiltscher¹, Michele Governale², and Jürgen König¹ — ¹Theoretische Physik, Universität Duisburg-Essen and CeNIDE, 47048 Duisburg, Germany — ²School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand

We adress the issue of coherence of transport through interacting quantum dots. For that purpose we consider an Aharonov-Bohm interferometer (ABI) with a single-level quantum dot embedded in one of the arms. For studying the role of spin we choose one lead to be ferromagnetic. We employ a diagrammatic real-time formalism where a perturbation expansion in the tunnel-coupling strength between dot and leads is performed, taking into account the Coulomb interaction non perturbatively [1].
Cotunneling through a quantum dot yields dephasing whenever the spin on the dot is flipped [2]. In the absence of Coulomb interaction transport is fully coherent and the total current is flux dependent. For an infinite interaction on the dot the AB oscillations are strongly influenced by the polarization and the transport direction. We discuss for different transport regimes which information the AB amplitude provides about coherence.
[1] König and Gefen, PRL 86, 3855 (2001) and PRB 65, 045316 (2002).
[2] Aikawa et al., PRL 92, 176802 (2004); Ihn et al., NJP 9, 111 (2007).