ESR of Gd3+ in the intermediate-valence YbInCu4 and its reference compound YInCu4

Electron-spin-resonance (ESR) experiments on Gd3+ in the intermediate-valence phase (T < T-v) of YbInCu4 and in its reference compound YInCu4 are interpreted in terms of an enhanced density of states at the Fermi level for the Yb-based compound. The Korringa rate and g shift measured in ESR and the susceptibility data allowed us to extract the electron-electron exchange enhancement factor alpha for the Yb-based compound. The exchange interaction between the Gd3+ local moments and the conduction electrons (c-e) is c-e wave-vector dependent in both compounds.5521016102