Observation of Kondo resonance in YbAl3

Anderson Hamiltonian parameters for mixed-valence YbAl3 were determined from the magnetic susceptibility, photoelectron-spectroscopy, and bremsstrahlung-isochromat-spectroscopy data. The 4f/sup 13/→4f/sup 14/ electron affinity energy is ∼0.5 eV and the hybridization between Yb 4f and Al conduction electrons is ∼0.05 eV, both of which are larger than conventional estimates. This hybridization and the resulting Kondo resonance are considered to play important roles for the anomalous properties of valence-fluctuating Yb compounds, as in the case of Ce compounds