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arXiv · 1012.1179

Magnetic polaron formation and exciton spin relaxation in single CdMnTe quantum dots

Łukasz Kłopotowski·Łukasz Cywiński·Piotr Wojnar·Valia Voliotis·Krzysztof Fronc·Tomasz Kazimierczuk·Andrzej Golnik·Marco Ravarro·Roger Grousson·Grzegorz Karczewski·Tomasz Wojtowicz
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Abstract

We study the formation dynamics of a spontaneous ferromagnetic order in single self-assembled CdMnTe quantum dots. By measuring time-resolved photoluminescence, we determine the formation times for QDs with Mn ion contents x varying from 0.01 to 0.2. At low x these times are orders of magnitude longer than exciton spin relaxation times evaluated from the decay of photoluminescence circular polarization. This allows us to conclude that the direction of the spontaneous magnetization is determined by a momentary Mn spin fluctuation rather than resulting from an optical orientation. At higher x, the formation times are of the same order of magnitude as found in previous studies on higher dimensional systems. We also find that the exciton spin relaxation accelerates with increasing Mn concentration.

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Łukasz Kłopotowski, Łukasz Cywiński, Piotr Wojnar, Valia Voliotis, Krzysztof Fronc, Tomasz Kazimierczuk, Andrzej Golnik, Marco Ravarro, Roger Grousson, Grzegorz Karczewski, Tomasz Wojtowicz. 2010-12-06. Magnetic polaron formation and exciton spin relaxation in single CdMnTe quantum dots. https://doi.org/10.1103/physrevb.83.081306

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