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An experimental and theoretical study of the magnetic polaron states of two-dimensional excitons in quantum wells based on semimagnetic semiconductors (Cd,Mn)Te is reported. It is shown that magnetic-polaron formation in in-plane magnetic fields leads to a lowering of the system symmetry, provided the fields are not too strong. The magnetic moment of the polaron thus formed is not parallel to the external magnetic field and contains a component normal to the quantum-well plane. This spontaneous lowering of the symmetry results in a change of the polarization characteristics of the luminescence from magnetic polaron states and in a weakening (compared to the three-dimensional case) in the efficiency of magnetic field-induced polaron suppression.

We report on growth by molecular beam epitaxy and magnetooptical investigations of digital alloys of diluted magnetic semiconductors. The digital alloys, i.e., very short-period superlattices, of interest here, were grown from nonmagnetic CdTe and magnetic Cd1−xMnxTe. In particular, quantum well structures containing the digital alloys in the regions of the quantum wells were fabricated. We searched for theoretically expected modifications of magnetic properties of digitally grown materials compared to those of random substitutional alloy counterparts. We monitored the magnetic behavior in our samples by studying their magnetooptical properties. We detected clear differences between magnetizations in random and digital alloys in samples grown along the 〈100〉 crystallographic direction. Unexpectedly, no modification of the spin-splitting (and, thus, of the magnetization) were observed in the case of digital quantum wells grown in the 〈120〉 crystallographic direction. On the other hand, exciton magnetic polaron binding energy in the latter structures was consistently greater by 10–20% than this quantity in similar samples grown along the 〈100〉 direction. The increase can be qualitatively understood in terms of the heavy hole mass anisotropy.