SPIN SUPERLATTICE FORMATION IN ZNSE-BASED DILUTED MAGNETIC SEMICONDUCTOR HETEROSTRUCTURES

We have observed spin-polarized confinement of both electrons and holes in ZnSe-based single and multiple quantum well structures. The samples were grown by molecular beam epitaxy with 100 angstrom Zn0.99Fe0.01Se barriers and 100-200 angstrom ZnSe wells. In these systems, the band offsets are very small, so that the large spin-splitting of the diluted magnetic semiconductor levels dominates the alignment of both the conduction and valence bands, permitting magnetic field-tunable confinement. Magnetoreflectivity measurements show a pronounced asymmetry of the heavy hole spin-splitting, a signature of spin-dependent quantum confinement. The relative phase and near-unity intensity ratio of the "spin-up" and "spin-down" excitons confirm localization of spin-up carriers to the ZnSe wells and spin-down carriers to the ZnFeSe layers, producing a field-tunable "spin-superlattice." These results will be compared to those obtained for higher magnetic ion concentrations in the barriers.