Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 69: Quantum Dots and Wires: Transport Properties II (mainly Quantum Dots)
HL 69.1: Vortrag
Mittwoch, 28. März 2012, 17:15–17:30, EW 203
Influence of spin relaxation and Coulomb correlations on the dynamics of an open quantum dot — •Benjamin Baxevanis1, Andreas Beckel2, Bastian Marquardt2, Martin Geller2, Axel Lorke2, and Daniela Pfannkuche1 — 1I. Institut für Theoretische Physik, Universität Hamburg, Germany — 2Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, Duisburg, Germany
The significance of Coulomb interaction and spin relaxation on the time-dependent dynamics of a quantum dot that is weakly coupled to an electronic reservoir is investigated. The two systems are assumed to be initially separated and we calculate the time evolution as the tunneling between the reservoir and the quantum dot is instantly switched on. The charging of a single quantum dot in the sequential tunneling regime is determined by using a master equation for the occupation probabilities. To incorporate many-body effects the eigenstates of a finite number of correlated electrons in the quantum dot obtained by the exact diagonalization method are taken into account.
The electrons in the quantum dot can interact with phonons and the electron spin can couple to their orbital motion or to nuclear spin which leads to relaxation. We consider two types of relaxation processes: 1. an orbital relaxation in the dot, which is instantaneous compared to the tunneling dynamics and 2. a spin relaxation with a time scale, which can be in the order of the tunneling times. We compare how different spin-relaxation times and the Coulomb correlations impact the charging dynamics of the quantum dot.