Soft x-ray energy-dependent angle-resolved photoemission study of CeIrIn5

Soft x-ray energy-dependent angle-resolved photoemission measurements are performed on the heavy-fermion superconductor CeIrIn5 to study the Fermi surface (FS) and the electronic structure near the Fermi level in the ΓMZA plane. The non-dispersive band designated as the Ce 4f7/21 final state is found at 280 meV along with the main body of the valence band consisting of highly dispersive In 5p bands, which are in good qualitative agreement with the band structure calculation based on the itinerant 4f electron model. Furthermore, we found two electron-like and one hole-like cylindrical FSs at the M (A) and Γ (Z) points. The Fermi momenta of the observed FSs are consistent with the de Haas–van Alphen experiment, while they contradict the stronger anisotropy of the FS along the kz direction predicted by the band calculation. The results suggest stronger two-dimensionality of the electronic structure of CeIrIn5 and point to the need for its theoretical verification.