The mixed-valence state of Ce in the hexagonal CeNi₄B compound

Measurements of the magnetic susceptibility χ, x-ray photoemission spectra (XPS), electrical resistivity ρ and electronic structure calculations for CeNi₄B are reported. In the paramagnetic region, CeNi₄B follows the Curie–Weiss law with µ_eff = 0.52µ_B/fu and θ = −10.7 K. The effective magnetic moment is lower than the free Ce³⁺-ion value. The Ce(3d) XPS spectra have confirmed the mixed-valence state of Ce ions in CeNi₄B. The f occupancy, n_f, and the coupling Δ between the f level and the conduction states were derived to be about 0.83 and 85 meV, respectively. Both susceptibility data and XPS spectra show that Ce ions in CeNi₄B are in the intermediate-valence state. At low temperatures (below 12 K), the magnetic contribution to the electrical resistivity reveals a logarithmic slope characteristic of Kondo-like systems.