Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 37: Quantum Dots and Wires: Optical Properties I (mainly InGaAs Dots)
HL 37.1: Vortrag
Dienstag, 27. März 2012, 10:45–11:00, ER 164
Time resolved Faraday rotation and ellipticity experiments with two pump excitation of electrons and holes in InGaAs QDs — •Dennis Barmscheid1, Steffen Varwig1, Irina A. Yugova1,2, Alex Greilich1, Alexander Schwan1, Crispin Müller1, Dmitri R. Yakovlev1, Dirk Reuter3, Andreas D. Wieck3, and Manfred Bayer1 — 1Experimentelle Physik II, TU Dortmund, D-44221 Dortmund, Germany — 2Institute of Physics, St. Petersburg State University, 198504 St. Petersburg, Russia — 3Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
The investigation of charge carrier spin dynamics in quantum dots plays an important role for the developement of spintronics. For this we perform pump-probe Faraday rotation and ellipticity experiments on self-assembled (In,Ga)As/GaAs quantum dot ensembles.
Due to an excitation with a train of pump pulses, the phase of the spin precessions in the inhomogeneous QD-ensemble is synchronized to the laser repetition time TR. By two pump excitation scheme, with pumps separated by delay TD, the spins have to fulfill two phase synchronization conditions simultaneously and show rephasing within TD and TR−TD. This leads to increases of the signal amplitude, called bunches, every multiple of TD.
It can be shown, that these bunches are different phenomena than the spin echoes, which occur after spin rotations. We show how this method provides an additional opportunity to study the interaction of electrons and holes with the nuclei.