Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 35: II-VI semiconductors III
HL 35.1: Talk
Wednesday, March 29, 2006, 14:30–14:45, POT 151
Optical orientation and thermal relaxation of excitons in semimagnetic CdMnSe/ZnSe quantum dots — •Thomas Schmidt1, Michael Scheibner1,2, Lukas Worschech1, Alfred Forchel1, Taras Slobodskyy3, and Laurens Molenkamp3 — 1Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Naval Research Laboratories, Washington, DC 20375 USA — 3EP III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
Polarization dynamics of quantum dots (QDs) represent actually an intensely studied field of research. Of special interest are semimagnetic quantum dots due to their distinct magnetic properties caused by the interaction of carrier spins with the Mn spin system. It is clear that with decreasing Mn content the semimagnetic properties are reduced. We have studied the polarization dynamics of a series of optical orientation and thermal relaxation of excitons in CdMnSe/ZnSe quantum dots for different Mn contents ranging from 0 to 2%. From the dependence of the polarization on the magnetic field strength we determined the exciton g factors of the QDs for different Mn contents and the relevant spin relaxation times. In particular, we have been able to resolve the sign reversal of the g factor. In QDs with negligible g factor the polarization properties are dominated by the optical orientation of the excited light. The spin relaxation times extracted from the thermal relaxation depend sensitively on the Mn concentration in a range of a few picoseconds.