Temperature dependence of the Kondo resonance in YbAl₃

We report the observation of a strong temperature dependence of the Kondo resonance in the valence-band photoemission spectrum and of the 3d --> 4f white line in the x-ray absorption spectrum of YbAl3. The asymmetric Kondo resonance has a binding energy of approximately 35 meV with a approximately 50 meV width. The temperature dependence of the Yb 4f spectral features and valence are well reproduced by Anderson impurity calculations with a Kondo temperature of T(K) almost-equal-to 400 K, demonstrating that both spectroscopic and near ground state properties can be described within a unified theoretical framework