ACTA

Femtosecond Dynamics of Neutral and Charged Exciton Absorption in Cd_1-xMn_xTe Quantum Well

P. Płochocka^a, P. Kossacki^a, W. Maślana^a, C. Radzewicz^a, J.A. Gaj^a, J. Cibert^b and S. Tatarenko^b
^aInstitute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warsaw, Poland
] ^bLaboratoire de Spectrometrie Physique, CNRS et Universite Joseph Fourier -- Grenoble B.P. 87, 38402 Saint Martin d'Heres Cedex, France

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We present a study of time-dependent transmission spectra of a modulation-doped Cd_1-xMn_xTe/Cd_1-y-zZn_yMg_zTe quantum well with variable hole gas concentration. We study the influence of pump pulses on excitonic absorption in subpicosecond time scale. A spectrally broad probe pulse of duration of 40 femtoseconds was used to record the absorption spectra at controlled delay. Studies of temporal evolution of exciton energies revealed coherence decay of linearly polarized excitons and thermalization of non-equilibrium exciton states. We found that a characteristic timescale for thermalization of non-equilibrium populations of photocreated excitons is between 0.8 and 3.6 ps. The timescale of this process depends on the hole concentration in quantum well: for higher hole concentration the decay is faster. Long-lived photo-induced magnetization accompanied by heating of the magnetic system was also observed.

DOI: 10.12693/APhysPolA.102.679
PACS numbers: 78.40.Fy, 78.47.+p, 78.67.De