Impact of the Ce 4f states in the electronic structure of the intermediate-valence superconductor CeIr₃

Abstract

The electronic structure of the f-based superconductor C e I r 3 was studied by photoelectron spectroscopy. The energy distribution of the C e 4 f states were revealed by the C e 3 d − 4 f resonant photoelectron spectroscopy. The C e 4 f states were mostly distributed in the vicinity of the Fermi energy, suggesting the itinerant character of the C e 4 f states. The contribution of the C e 4 f states to the density of states (DOS) at the Fermi energy was estimated to be nearly half of that of the I r 5 d states, implying that the C e 4 f states have a considerable contribution to the DOS at the Fermi energy. The C e 3 d core-level and C e 3 d x-ray absorption spectra were analyzed based on a single-impurity Anderson model. The number of the C e 4 f states in the ground state was estimated to be 0.8 − 0.9 , which is much larger than the values obtained in the previous studies (i.e. 0 − 0.4 ).