Transient level crossing of free and bound excitonic magnetic polarons in Cd1−xMnxTe

We report an experimental evidence of the existence of free excitonic magnetic polaron (FEMP) states from the study of the dynamics of free and bound excitons in View the MathML source by time-resolved photoluminescence measurements. We found, for the first time, that FEMP are more stable than the polarons formed from bound excitons. The polaron binding energy for the free excitons is evaluated to be View the MathML source, which is considerably larger than that of View the MathML source found for the magnetic polarons of the bound excitons; these values were determined from the suppression of the excitonic energy relaxation in high magnetic fields. As a consequence, the peak energies of the optical emissions of free excitons and donor-bound excitons cross in the time-resolved photoluminescence spectra.