The Yb2+ component of the hybrid ground state and the temperature dependence of the Yb 4f occupation in YbAgCu4 and YbInCu4 was probed by using resonant inelastic X-ray scattering (RIXS) method. Temperature-dependent measurements on the normal Kondo system YbAgCu4 were equally illuminating while the intensity of the 2+ RIXS feature was found to decrease with increasing temperature. The results showed sharp valence transition in YbInCu4 and the characteristic temperature dependence of the 4f occupation in YbAgCu4 which provided strong evidence of a spectroscopic Kondo energy scale for valence fluctuators.
ASJC Scopus subject areas
- Physics and Astronomy(all)