Band Dependent Interlayer f -Electron Hybridization in CeRhIn5

A key issue in heavy fermion research is how subtle changes in the hybridization between the 4 f (5 f ) and conduction electrons can result in fundamentally different ground states. CeRhIn₅ stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn₅ , we demonstrate that the use of resonant angle-resolved photoemission spectroscopy with polarized light allows us to extract detailed information on the 4 f crystal field states and details on the 4 f and conduction electron hybridization, which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f electrons and identify two of the three Ce 4 f₅^{/2 1} crystal-electric-field levels and band-dependent hybridization, which signals that the hybridization occurs primarily between the Ce 4 f states in the CeIn₃ layer and two more three-dimensional bands composed of the Rh 4 d and In 5 p orbitals in the RhIn₂ layer. Our results allow us to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound.