Angle-resolved and resonant photoemission spectroscopy on heavy-fermion superconductors Ce2CoIn8 and Ce2RhIn8

We have carried out high-resolution angle-resolved and resonant photoemission spectroscopy (RPES) on heavy-fermion superconductors Ce2CoIn8 and Ce2RhIn8 to study the electronic band structure and the nature of the Ce 4f electrons. We have experimentally determined the valence-band structure and compared them with the full-potential linear augmented plane-wave band calculations. We found that both compounds have quasi-two-dimensional cylindrical Fermi surfaces centered at the M(A) point in the Brillouin zone, which may be an essential parameter for the development of the superconductivity. Comparison with the band calculations based on the itinerant and localized models suggests that the Ce 4f electrons are essentially localized in both compounds at a measured temperature of 40K. RPES results have confirmed the localized character of the Ce 4f electrons in both compounds, with a relatively stronger localized nature in Ce2RhIn8 than in Ce2CoIn8. This difference in the strength of localized character well explains the difference in the magnetic properties between the two compounds.