Magneto-optic study of the interface in semimagnetic semiconductor heterostructures: Intrinsic effect and interface profile in CdTe-${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te

This paper is devoted to the description of the interface between a semimagnetic semiconductor (${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Te) and a nonmagnetic one (CdTe), and to the study of its magnetic and magneto-optical properties, as revealed through the enhanced Zeeman splitting of carriers confined in heterostructures. The model (proposed earlier on phenomenological bases) takes into account both the chemical profile of the imperfect interface and the enhanced magnetism due to the reduced number of magnetic neighbors at the interface. We first justify the model (for low Mn contents) by considering the statistics of Mn clusters at the interface or in a single ${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Te monolayer embedded in CdTe. We also show that the sensitivity of the Zeeman effect to the presence of two-dimensional islands at the interface rapidly decreases as the island width increases; i.e., the measure is sensitive to the presence of isolated magnetic ions and not (or less) to roughness, and it characterizes the interface on the scale of interatomic distance. Then we apply this tool to a wide series of samples with different nominal characteristics and different growth conditions.