Neutron diffraction and reflectivity studies of Eu chalcogenide based superlattices

Neutron diffraction and reflectivity experiments performed on a number of magnetic semiconductor superlattices (SL), in search for interlayer coupling, are presented. Antiferromagnetic (AFM) EuTe/PbTe SL's and ferromagnetic (FM) EuS-based multilayers, with narrow-gap semiconductor (PbS) as well as insulating (YbSe) diamagnetic spacers, were studied. Pronounced interlayer magnetic correlations have been revealed in EuTe/PbTe by neutron diffraction. In the FM multilayers it was proven by neutron diffraction and reflectivity experiments that consecutive EuS layers are antiferromagnetically coupled. The strength of the AFM IC in EuS-based systems, determined by neutron reflectivity measurements in applied magnetic fields, was compared with the predictions of a tight-binding model. The results of theoretical calculations have been found to be in good qualitative agreement with the experimental data. Finally, the in-plane anisotropy and the in-plane magnetic domain population were studied by polarized neutron reflectivity. It was established that the preferred orientation of domain magnetization in each system coincides with one of the two possible in-plane easy axes: namely, with [2 1 0] in EuS/PbS, and with [1 1 0] in EuS/YbSe.