Cold and Hot Excitons in CdMnTe/CdMgTe Quantum Wells in Strong Excitation Regime and External Magnetic Field

A. Trajnerowicza, A. Golnika, P. Kossackia, W. Bardyszewskib, M. Wiaterc, G. Karczewskic and T. Wojtowiczc a Institute of Experimental Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland b Institute of Theoretical Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland c Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland

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Systematic studies of neutral heavy hole excitonic line energy changes in a strong excitation regime were carried out by means of a pump probe method for quantum wells containing a 2D gas of free holes. Energy shift of Xe1hh1 line was analyzed for different excitation energies at fixed delay between pump and probe pulses, also under external magnetic field. It was observed that this shift depends not only on the density of created excitons but also directly on the pump energy. In co polarization configuration for excitation energy below an absorption resonance the energetic blue shift rises linearly with the elevated exciton density (localized excitons are created). For energies slightly above the resonance, the blue shift diminishes dramatically in spite of high exciton density present (delocalized excitons are created). Model absorption calculations are in qualitative agreement with the experimental data.

DOI: 10.12693/APhysPolA.116.849 PACS numbers: 78.67.De, 71.35.Lk, 78.47.-p