Quantitative study of the f occupation in Ce M In 5 and other cerium compounds with hard X-rays

We present bulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES) data of the Ce3d core levels and lifetime-reduced Ledge x-ray absorption spectroscopy (XAS) in the partial fluorescence yield (PFY) mode of the CeMIn 5 family with M = Co, Rh, and Ir. The HAXPES data are analyzed quantitatively with a combination of full multiplet and configuration interaction model which allows correcting for the strong plasmons in the CeMIn 5 HAXPES data, and reliable weights w n of the different f n contributions in the ground state are determined. The CeMIn 5 results are compared to HAXPES data of other heavy fermion compounds and a systematic decrease of the hybridization strength V eff from CePd 3 to CeRh 3 B 2 to CeRu 2 Si 2 is observed, while it is smallest for the three CeMIn 5 compounds. The f-occupation, however, increases in the same sequence and is close to one for the CeMIn 5 family. The PFY-XAS data confirm an identical f-occupation in the three CeMIn 5 compounds and a phenomenological fit to these PFY-XAS data combined with a configuration interaction model yields consistent results.