STRUCTURAL AND MAGNETIC-PROPERTIES OF LA FE MULTILAYERS/

The structural and magnetic properties of La/Fe multilayers were inves tigated by X-ray diffraction, RHEED, magnetometry and Fe-57 Mossbauer spectroscopy. Comparison is made with previous results obtained for Ce /Fe multilayers. Remarkably sharp interfaces are found, with roughness between 2 and 2.5 Angstrom. The magnetic interface in the Fe sublayer s resulting from the distribution of magnetic hyperfine fields distinc tly exceeds the extension of the structural interface and points to a magnetic proximity effect. This is discussed in relation to a strong 3 d-5d hybridization recently found in measurements of magnetic circular X-ray dichroism. Both the structural and magnetic La/Fe interface is less extended than the interface in Ce/Fe multilayers. Below a thickne ss of about 25 Angstrom, the individual Fe layers grow in an amorphous structure on the La layers. In this case, Curie temperatures are belo w 200 K and the Fe-layer saturation magnetization is reduced up to 50% , and there is evidence of a non-collinear spin structure. It is argue d that this mainly reflects the properties of pure amorphous Fe.