MAGNETIC-PROPERTIES OF REFE2, CEFE2, GDFE2, LUFE2 - COMPOUNDS STUDIED BY MAGNETIC-X-RAY DICHROISM

Magnetic X-ray dichroism (MXD) experiments have been performed on several REFe2 Laves phases compounds (RE: Ce, Gd, Lu), both at the K edge of iron and at the L(III) edges of the rare-earth elements. In all compounds large spin-dependent absorption effects are observed, below the Curie temperatures, at both the K edges of iron and the L(III) of the rare earth. In the case of CeFe2, the MXD signal observed at the Ce edges follows the same temperature dependence as the bulk magnetization and confirms that an ordered magnetic moment develops at the Ce sites in this mixed-valence compound. A special attention is given to the problem of final-state effects in the description of MXD experiments on cerium, particularly we show that the spin-dependent absorption cross-section reproduces the well-known <<double-bump>> structure, typical of cerium mixed-valence compounds.