Direct observation of a quasiparticle band in CeIrIn5 : An angle-resolved photoemission spectroscopy study

We have performed a high-resolution angle-resolved Ce 4d-4f resonant photoemission experiment on the heavy fermion superconductor CeIr In5. We have observed a quasiparticle band, which has an energy dispersion of ∼30 meV in the Ce 4f on-resonance spectra. The result suggests that although the 4f spectra are dominated by the localized and/or correlated character, the small itinerant component is responsible for the superconductivity in this compound