Magnetic and thermodynamic properties of EuS/SrS multilayers at low temperatures

The magnetization, susceptibilityX and specific heatC of epitaxially grown EuS/SrS multilayers measured at low temperatures is reported.C changes with decreasing thickness of the individual EuS and SrS layers, i.e. decreasing modulation length, from the behavior of nearly pure EuS(CT^3/2) to a behavior resembling that of spin-glass samples of Eu_xSr_1–xS (approximatelyC T). For multilayers with increasing thickness ratior =d_M/d_N (M=EuS,N=SrS),C decreases towards pure EuS, thus showing a transition from spin-glass to ferromagnet. The paramagnetic Curie temperature obtained fromX is reduced with respect to that of pure EuS for layers with small EuS layer thickness. All these effects can be explained by the formation of Eu_xSr_1–xS intrrmediate diffusion layers of a fewnm thickness during the evaporation process. Reduction of the substrate temperature results in a much smaller diffusion layer.Dedicated to Prof. Dr. G. von Minnigerode on the occasion of his 60th birthday