Temperature dependence of the Kondo resonance in YbAl3.

Abstract

We report the observation of a strong temperature dependence of the Kondo resonance in the valence-band photoemission spectrum and of the 3d\ensuremath{\rightarrow}4f white line in the x-ray absorption spectrum of ${\mathrm{YbAl}}_{3}$. The asymmetric Kondo resonance has a binding energy of \ensuremath{\sim}35 meV with a \ensuremath{\sim}50 meV width. The temperature dependence of the Yb 4f spectral features and valence are well reproduced by Anderson impurity model calculations with a Kondo temperature of ${\mathit{T}}_{\mathit{K}}$\ensuremath{\approxeq}400 K, demonstrating that both spectroscopic and near ground state properties can be described within a unified theoretical framework.