Magnetic Phase Transition of CeSb Studied by Low-Energy Angle-Resolved Photoemission Spectroscopy

We have performed low-energy ultrahigh-resolution angle-resolved photoemission spectroscopy on CeSb to elucidate the bulk electronic structure responsible for the magnetic phase transition. By using a newly developed xenon-plasma discharge lamp, we clearly observed the splitting of Sb 5p(3/2) and Cc 5d bands near the Fermi level as well as their strong hybridization below the Neel temperature (T-N = 16 K). We also revealed distinct differences in the band structure between the antiferropara- and antiferromagnetic phases. These experimental results are discussed in terms of the p-f/p-d mixing effect, the exchange splitting, and the magnetic band-folding. The present result also explains the emergence of fine structures in the optical conductivity in the magnetic phase.