Electronic structure studies of CeRhSb with Rh substituted by Pd and Ni

We have investigated the influence of the valence of Ce ions on the gap formation in CeRhSb-type Kondo insulators. We present the 3d x-ray photoemission spectroscopy (XPS) spectra for CeRhSb, CeRh 1 - x Pd x Sb, and CeRh 1 - x Ni x Sb compounds. From the experimental Ce 3d XPS spectra we extracted the spectral weight of the different 3d 9 f 0 , 3d 9 f 1 , and 3d 9 f 2 final states. We used the Doniach-Sunjic method to separate the overlapping peaks in the 3d XPS spectra. Analysis of the 3d 9 f 2 weight using Gunnarsson-Schonhammer theory suggests a hybridization interaction A of about 150 meV for CeRhSb. The hybridization energy A obtained for CeNiSb and CePdSb is ∼3 times smaller than that of the Kondo insulating compound CeRhSb. Analysis of the 3d 9 f 0 component indicates a mixed valence of Ce in CeRhSb, and a stable configuration of Ce in the Ni or Pd alloys. The experimental results indicate the influence of atomic disorder on the magnetic behavior of CePdSb and CeNiSb.