EXCITON MAGNETIC POLARONS IN SEMIMAGNETIC QUANTUM-WELLS WITH NONMAGNETIC AND SEMIMAGNETIC BARRIERS

We report on the optical study of exciton magnetic polarons in structures with semi-magnetic Cd1-yMnyTe quantum wells sandwiched between nonmagnetic Cd1-xMgxTe or semimagnetic Cd1-xMnxTe barriers. We have found magnetic polarons with energy of 9 meV formed from quasi-two-dimensional excitons in Cd0.9Mn0.1Te/Cd0.7Mg0.3Te quantum wells with thicknesses varying from 18 to 100 angstrom, but no polaron formation has been found for quasi-three-dimensional excitons situated in quantum wells thicker than 300 angstrom. The experimentally established effect of the dimensionality of the system on the stability of exciton magnetic polarons is in qualitative agreement with theoretical predictions. In Cd1-yMnyTe/Cd1-xMnxTe structures contributions of the carrier exchange with Mn spins located in the well and in the barrier layers are responsible for the process of magnetic polaron formation. Relation of these contributions has been demonstrated to be controlled by the quantum well width.