Ferromagnetic semiconductor superlattices studied by polarized neutron reflectometry

The results of extensive neutron reflectometry studies of EuS-based ferromagnetic semiconductor superlattices (SL's) which exhibit interlayer exchange coupling (IEC) are presented. The SL's grown on two different substrates, (0 0 1)KCl and (1 1 1)BaF2, with two types of nonmagnetic spacer material, PbS (narrow gap) and YbSe (wide gap semiconductor), were investigated. Neutron reflectometry measurements revealed pronounced antiferromagnetic IEC in the systems grown on (0 0 1)KCl substrate, whereas in the EuS/PbS superlattices grown on (1 1 1)BaF2 a ferromagnetic IEC has been found. The in-plane magnetic anisotropy and the population of the magnetic domains were studied by polarized neutron reflectivity. The in-plane directions of easy-axes has thus been determined in the all investigated systems. A nonuniform distribution of domains magnetization directions among the easy in-plane axes has been found.