Large Fermi-level resonance in the electron-addition spectrum of CeRu2and CeIr2

Abstract
We report that the electron-addition spectra of superconducting CeIr2 and CeRu2, which are extreme examples of α-cerium-like behavior, display a very large peak of unresolved sharpness and position immediately above the Fermi level. We point out that such a peak is expected for a nonmagnetic system described by the Anderson Hamiltonian, and discuss its spectral weight and composition.