Electronic structure of cage-type ternaries ARu2Al10 – Theory and XPS experiment (A = Ce and U)

The electronic structure of the isomorphic, orthorhombic URu2Al10 and CeRu2Al10 aluminides have been studied by X-ray photoelectron spectroscopy (XPS) and ab initio calculations using the fully relativistic full-potential local-orbital (FPLO) method within the local density approximation (LDA). The calculated data of the former system revealed fairly sharp triple-peaks of the U 5f states around the Fermi level (EF) and a large broad contribution from the Ru 4d states expanded from EF to about 6.5 eV of binding energy. Although the size and positions of the Ru 4d bands for the latter compound are quite similar to those of the U-based one, the double Ce 4f sharp peaks are placed almost completely above EF underlying their mostly localized character. We have also analyzed the Fermi surfaces (FSs) in these two aluminides. The calculated results of both ternaries were then compared with our experimental XPS data for URu2Al10 and with such data for CeRu2Al10 available in the literature. The results are in fairly good agreement between the theory and experiment. Especially, the fact that the spectrum weight of the Ce 4f electrons below EF turned out to be very much reduced, reflecting rather a small f–c hybridization of these electrons compared to considerably larger one in the U-based compound.

► Electronic structures of (U;Ce)Ru2Al10 probed by X-ray photoemission and ab initio.
► Good agreement between valence-band XPS and calculated (within LDA) spectra.
► More itinerant character of the U 5f than Ce 4f electrons in these compounds.
► Reduced Fermi surface of CeRu2Al10 compared with the U-based system.