INTERFACIAL MAGNETISM OF CE/FE AND CEH-SIMILAR-TO-2/FE MULTILAYERS STUDIED BY FE-57 MOSSBAUER-SPECTROSCOPY

The distribution of the magnetic hyperfine fields and the magnetic anisotropy of Ce/Fe and CeH approximately2/Fe multilayers have been studied by Mossbauer spectroscopy between 4.2 and 300 K. The extension of the Ce-Fe interaction defining a 'magnetic interface' exceeds the structural extension of the interface and is more than two times larger at the Ce/Fe than at the CeH approximately2/Fe interface. This is proposed to be a consequence of a strong hybridization between the Ce-5d and Fe-3d states that is suppressed by hydrogenation. From the relative intensity of the Mossbauer lines we show that for the CeH approximately2/Fe system with sufficiently thin Fe layers the orientation of the spontaneous magnetization is perpendicular to the film plane at low temperatures and switches to a parallel alignment at higher temperatures in a sharp transition. In contrast, the Ce/Fe system is spontaneously magnetized in the film plane.