Characterization of the hybridized4fstates in YbAl3by high-energy spectroscopies

Abstract

The intermetallic compound Yb${\mathrm{Al}}_3$ has been studied by bremsstrahlung isochromat spectroscopy, x-ray photoemission, and high-resolution (<20 meV) uv photoemission using He i and He ii lines. The spectra analysis with the Anderson single-impurity model for $T=0\mathrm{}$ reveals a ground state with an important hybridization of $f$ states with band states, corresponding to an $f$ population $n_f=13.5\mathrm{}$. In contrast to all investigated metallic Ce systems which are in the Kondo regime, Yb${\mathrm{Al}}_3$ is found to be in the mixed-valence regime. A rough calculation provides an explanation for the comparable hybridization strengths observed in Ce and Yb systems.