Band gap stability in CeRhSb

The electronic structure and magnetic properties of CeRhSb were investigate d by substituting Rh with 10% of Pd or Co, or Sb with 10% Sn. The 3d and 4d x-ray photoelectron spectroscopy (XPS) spectra show that CeRhSb and its al loys with Pd and Co are mixed valent. For Sn, the spectra are consistent wi th trivalence. Analysis of the f(2) weight in the 3d XPS spectra using Gunn arsson-Schonhammer theory suggests a hybridization constant of 140 meV for CeRhSb and about 170 meV for its alloys. Linearized muffin-tin orbital calc ulations give a pseudo-V-shape gap located at the Fermi level. This classif ies these materials as semimetals rather than semiconductors. The location of the pseudogap in CeRhSb varies with the number of valence electrons. We discussed the correlation between the gap at the Fermi level and the number of free electrons, the valence of Ce, and the f-d hybridization. [S0163-18 29(98)00644-4].