Magneto-photoluminescence spectroscopy of ZnMnTe/ZnMgTe spin superlattice

In this work, we studied the magneto-optical properties of ZnMnTe/ZnMgTe spin superlattices by using photoluminescence (PL) spectroscopy at low temperature. The circularly polarized PL measurements in an increasing magnetic field were performed. Detailed characteristics of the level crossing behavior for the spin-polarized excitonic states due to the giant Zeeman splitting were observed. The results show that an increase of the magnetic field transfers the spin superlattices from direct band gap system to indirect band gap system, and spatially separates the electrons and the holes by changing type-I band alignment to type-II band alignment. These features are confirmed by the behavior of the PL intensity in magnetic field, and agree well with the theoretical expectation basing on the sp–d exchange interaction.