Magneto-optical studies of magnetic polarons in type-II (Zn,Mn)Te/ZnSe quantum dots

ORAL

Abstract

We have recorded time-resolved emission spectra from a series of MBE grown (Zn,Mn)Te/ZnSe quantum dots (QDs) at 7 K in the 0 - 4 tesla magnetic field range. The photoluminescence (PL) spectra were analyzed into their $\sigma $+ and $\sigma -$ circularly-polarized components. The holes in this type-II system are confined in the (Zn,Mn)Te QDs, while the electrons reside in the surrounding ZnSe matrix. The PL intensity, peak energy, and circular polarization were recorded as a function of time and magnetic field. These studies show evidence of exchange coupling between the holes and Mn spins in the (Zn,Mn)Te QDs, which leads to the formation of magnetic polarons. The time scale of polaron formation is shorter than the recombination time in this type-II system. We discuss our results within the framework of a model that describes the magnetic polaron formation in this system.

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Authors

  • Biplob Barman

    SUNY Buffalo

  • Andreas Russ

    SUNY Buffalo, University at Buffalo, The State University of New York

  • Lars Schweidenback

    SUNY Buffalo, University at Buffalo, The State University of New York

  • Joseph Murphy

    SUNY Buffalo

  • Rafal Oszwaldowski

    SUNY at Buffalo, University at Buffalo, SUNY Buffalo

  • Ian Sellers

    SUNY Buffalo

  • Athos Petrou

    University at Buffalo, The State University of New York, SUNY Buffalo

  • Igor Zutic

    SUNY at Buffalo, University at Buffalo, SUNY Buffalo

  • Bruce McCombe

    Dept of Physics, University at Buffalo, SUNY, State University of New York at Buffalo, SUNY Buffalo

  • Alexander Cartwright

    SUNY Buffalo

  • Andre Petukhov

    South Dakota School of Mines and Technology, South Dakota School of Mines \& Technology

  • Wu-Ching Chou

    National Chiao Tung University

  • Wen Chung Fan

    National Chiao Tung University