Observation of Itinerant Ce 4f Electronic States in CeIrSi3 Studied by Angle-Resolved Ce 3d→4f Resonance Photoemission Spectroscopy

Abstract

We have applied angle-resolved Ce 3 d →4 f resonance photoemission spectroscopy ( h ν∼882 eV) in the soft X-ray region to the analysis of the non-centrosymmetric pressure-induced superconductor CeIrSi 3 and obtained the 4 f band structure and Fermi surfaces. We have found that the Ce 4 f states are located mainly near the Fermi level and that the photoemission feature corresponding to the dispersive conduction bands across the Fermi level shows considerable resonant enhancement. In addition, the band structure and Fermi surfaces of CeIrSi 3 differ from those of the non- f reference compound LaIrSi 3 , and the differences are well explained by the band structure calculated within local density approximation, in which the Ce 4 f states are assumed to be itinerant. These results strongly suggest that the Ce 4 f electrons in CeIrSi 3 hybridized well with conduction bands and form itinerant electronic states.