Excitonic spin states and radiative recombinations in Cd1−xMnxTe/Cd1−yMgyTe spin superlattices

The formation of a spin superlattice structure was realized in Cd0.95Mn0.05Te/Cd0.95Mg0.05Te under a magnetic field. The experimental evidence of the spin superlattice structure was found from time-resolved polarized magneto-photoluminescence measurements, in the Zeeman splittings and the exciton magnetic polaron formation. The Zeeman splitting directly indicates the spatial separation of spin-up and spin-down electrons and heavy holes, which are localized in the Cd0.95Mg0.05Te and Cd0.95Mn0.05Te layers, respectively. The formation of exciton magnetic polarons under a magnetic field can be attributed to the spin-dependent confinement where a large polaron binding energy of 3.5 meV has been observed in 2.5 T to be enhanced by the field-induced localization of the excitons.