Role of magnetic/nonmagnetic semiconductor interfaces in magneto-optical properties of small-offset superlattices

Zn_1-xMnₓSe/ZnSe superlattices (SL's) involving magnetic/nonmagnetic interfaces were investigated by magnetoabsorption spectroscopy. The Mn concentration in the Zn_1-xMnₓSe layers ranged from $x=0.10$ to 0.14, resulting in small band offsets between barriers and wells of the SL's. The data were analyzed using the eight-band k·p model and the finite element method, taking into account interdiffusion of elements across the interface. We found that the Zeeman shifts of the ground- and excited-state transitions observed in all superlattices can be successfully explained by a single common profile of the graded interface, that extends over about three monolayers. In addition, the data revealed the presence of antiferromagnetic coupling between Mn ions across thin (less than 18 {}) ZnSe layers in the above Zn_1-xMnₓSe/ZnSe multilayer structures.