Changes of the Light-Hole Exciton Line in CdMnTe/CdMgTe Quantum Wells Under Resonant Excitation of the Heavy-Hole Exciton

Systematic studies of excitonic lines in the strong excitation regime were carried out by using a pump-probe method. Several samples containing quantum wells with different well widths (from 80 angstrom to 160 angstrom) were investigated. Most of the quantum wells were intentionally undoped but contained a 2D gas of free holes. The density of the free holes could be varied by changing the intensity of additional illumination. After resonant excitation of the heavy-hole exciton ground state by using an intense pump pulse we observed changes in the heavy- and the light-hole exciton lines. The resonant creation of a high population of e1hh1 excitons caused energetic blue shifts of the e1lh1 excitons. The blue shift in the experiment with opposite circularly-polarized pump and probe pulses could be explained as an interaction of electrons of the same spin bounded into the e1hh1 and the e1lh1 excitons. Model calculations of absorption showed qualitative agreement with the experimental data.