Evolution from antiferromagnetic to paramagnetic Kondo insulator with increasing hybridization; XPS studies

We present the Ce 3d x-ray photoemission (XPS) spectra for CeM₂Al₁₀ (M=Ru, Os, Fe) from which we determined the on-site hybridization between the f and conduction electron states, Δ_cf, and the 4f-level occupancy, n_f. Those parameters have been obtained using the Gunnarsson-Schönhammer approach. We found Δ_cf stronger for the Kondo insulator CeFe₂Al₁₀ than for the remaining compounds with Ru and Os. We discuss the type of behaviour of CeM₂Al₁₀ on the base of the earlier theoretical phase diagram obtained within the Anderson-lattice model.