Ferromagnetic transition in EuS-PbS multilayers

The magnetic properties of multilayers of ferromagnetic EuS intercalated with diamagnetic PbS were studied as a function of the EuS layer thickness (varying from 2 to 200 ML). The critical temperature TC of the paramagnet-ferromagnet phase transition was determined from magnetization vs temperature measurements and was found to depend on the underlying substrate [KCl (100) vs BaF2 (111)] as well as on the thickness of the EuS layer. For thick layers (dEuS˜200 ML), which mimic semibulk EuS, the TC values were found shifted with respect to the bulk EuS (about 1 K up for layers grown on KCl and about 3 K down for layers grown on BaF2). This effect is attributed to stress resulting mainly from the difference of thermal expansion coefficients between the substrate and the structure. For thin layers (dEuS2 Å magnetize in the plane of the structure