Observation of Kondo resonance in valence-ordered YbPd

摘要

We performed a point-contact spectroscopy study of intermediate valence compound YbPd, in which two Yb sites are ordered with the valence values of 3+ and 2.6+. Differential conductance spectra exhibit a dip structure at around zero bias with an asymmetric background, which can be reproduced by the summation of two Kondo resonances. Fitting with the Fano equation, the Kondo temperature of the 3+ site is estimated to be similar to 30K, while that of the 2.6+ site is similar to 800K. Additionally, the dip amplitude exhibits -lnT dependence below similar to 25K and saturates at similar to 1K. These results provide direct evidence for the screening of magnetic moments at the valence ordering sites owing to the Kondo effect.