Kerr effect investigations of magnetic interlayer interactions in EuS-PbS multilayers

K err magnet ometr y was employe d to study the temp erature dependence of magnet izati on and magnetic hysteresis loops in ferromagnetic EuS{ PbS semiconductor multilayers in the temp erature range T = 3 À 35 K at low mag - netic Ùelds H ç 1 5 0 Oe. For EuS{PbS /K Cl( 100) structures with ultrathi n non- magnetic PbS spacer of 1 nm , we observed a maximum on the temp erature dep endence of magnetizati on at low Ùelds H ç 30 Oe. For higher Ùelds, we found for these structures a regular mean- Ùeld-li ke increase in magnetization with decreasing temp erature. T he same regular beha vior was also found for EuS{PbS/K Cl structures with thicker PbS spacer, as well as for all EuS{PbS/ Ba F2 (111) multilayers indep endently of spacer thickness. For qualitati ve interpretation of these Ùndings, we consider two magnetic contributions to the total energy of EuS{PbS multilayers : the Zeeman energy and the antif erromagnetic interlayer exchange coupling betw een ferromagnetic EuS layers via diamagnetic PbS spacer