EXCITON MAGNETIC POLARONS IN CDTE CD1-XMNXTE QUANTUM-WELLS WITH HIGH MANGANESE CONTENTS/

We report on optical studies of exciton magnetic polarons in CdTe/Cd1- xMnxTe quantum well structures with Mn contents 0.4 less than or equal to x less than or equal to 0.8. The magnetic polaron energies and for mation times are measured by cw- and time-resolved photoluminescence u nder selective excitation. We find an overall increase of the polaron energy with increasing Mn-concentration in the whole range of Mn conte nts studied and attribute it to diffusion induced changes of the Mn pr ofile at the interfaces between nonmagnetic and semimagnetic layers. I n addition, we find that in these quantum structures the formation tim e of the polaron is predominantly determined by the Mn content and not by quantum confinement effects. The large band gap discontinuity (up to 1.2 eV) causes large splittings between heavy- and light-hole-state s and leads to a strong anisotropy in the suppression of the magnetic polaron formation by magnetic fields applied parallel and perpendicula r to the structure growth aids. For both orientations of magnetic fiel d the polaron suppression is qualitatively described by model calculat ions.