Exchange interactions in CdMnTe/CdMgTe quantum wells under high magnetic fields

Abstract

The sp–d exchange interaction J sp–d and the exchange interaction between the nearest neighbor Mn ions J NN were studied by magneto-photoluminescence spectra of excitons in CdMnTe/CdMgTe quantum wells in pulsed high magnetic fields up to 45 T . The magnitude of J sp–d estimated from the observed Zeeman splitting was found to decrease as the quantum well width was decreased. The decrease is partly due to the penetration of the electron and the hole wave functions into the non-magnetic CdMgTe barrier layers, and partly due to the k-dependence of the exchange interaction. It was found that the latter effect is much larger than theoretically predicted. The observed features are well explained by a model assuming the interface disorder within some thickness near the interface. In contrast to J sp–d, the nearest neighbor interaction J NN estimated from the steps in the photoluminescence peak was found to be independent of the well width.