Transient behavior of the excitonic magnetic polarons in Cd1-xMnxTe epilayers

We present a study of the dynamics of the excitonic magnetic polarons in Cd 1-xMnxTe epilayers. The transient photoluminescence measured by a streak ca mera under resonant excitation is analyzed with a special attention devoted to line shape of the emission signal. A nonradiative spectral region is ob served in zero field and is strongly suppressed in a field of 6 T. This obs ervation is understood to be directly related to the alignment of the Mn2spins and is therefore closely related to the formation of magnetic polaron s. A few Mn spins are found to be aligned already within 10 ps, but the tot al Mn spin polarization in the sample is found to increase exponentially wi th a rise time of 37 ps in Cd0.73Mn0.27Te epilayers. Furthermore, the value s of 19.2 and 12.4 meV were determined for the energies of the excitonic ma gnetic polarons in Cd0.73Mn0.27Te and Cd0.79Mn0.21Te epilayers, respectivel y. (C) 2000 American Institute of Physics. [S0021-8979(00)19508-8].