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Magnetic polaron formation and exciton spin relaxation in single Cd1xMnxTe quantum dots

Ł. Kłopotowski, Ł. Cywiński, P. Wojnar, V. Voliotis, K. Fronc, T. Kazimierczuk, A. Golnik, M. Ravaro, R. Grousson, G. Karczewski, and T. Wojtowicz
Phys. Rev. B 83, 081306(R) – Published 15 February 2011

Abstract

We study the formation dynamics of a spontaneous ferromagnetic order in single self-assembled Cd1xMnxTe quantum dots (QDs). 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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  • Received 1 December 2010

DOI:https://doi.org/10.1103/PhysRevB.83.081306

©2011 American Physical Society

Authors & Affiliations

Ł. Kłopotowski1,*, Ł. Cywiński1, P. Wojnar1, V. Voliotis2, K. Fronc1, T. Kazimierczuk3, A. Golnik3, M. Ravaro2, R. Grousson2, G. Karczewski1, and T. Wojtowicz1

  • 1Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02-668 Warsaw, Poland
  • 2Institut des NanoSciences de Paris, Université Pierre et Marie Curie, CNRS, 4 place Jussieu, F-75252 Paris, France
  • 3Faculty of Physics, University of Warsaw, ul. Hoża 69, PL-00-681 Warsaw, Poland

  • *lukasz.klopotowski@ifpan.edu.pl

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Issue

Vol. 83, Iss. 8 — 15 February 2011

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