4forbital and spin magnetism in cerium intermetallic compounds studied by magnetic circular x-ray dichroism

Magnetic circular x-ray dichroism experiments at the ${\mathit{M}}_{4,5}$ absorption edges of cerium in the intermetallic compounds CeCuSi, ${\mathrm{CeRh}}_3$ ${\mathrm{B}}_2$, and ${\mathrm{CeFe}}_2$ are reported. By applying general sum rules, it is shown that these experiments are able to yield both the magnitude and the direction of the 4f magnetic moment on Ce. An estimation of the orbital contribution to those 4f moments is given. Our experiments demonstrate the existence of a 4f magnetic moment on Ce in ${\mathrm{CeFe}}_2$ and confirm the extreme sensitivity of the 4f orbital contribution to the degree of localization of the 4f electrons. This 4f orbital contribution is significantly higher than the one predicted from spin-resolved band-structure calculations.