ESR OF GD3-VALENCE YBINCU4 AND ITS REFERENCE COMPOUND YINCU4( IN THE INTERMEDIATE)

Electron-spin-resonance (ESR) experiments on Gd3+ in the intermediate- valence phase (T < T-v) of YbInCu4 and in its reference compound YInCu 4 are interpreted in terms of an enhanced density of states at the Fer mi level for the Yb-based compound. The Korringa rate and g shift meas ured in ESR and the susceptibility data allowed us to extract the elec tron-electron exchange enhancement factor alpha for the Yb-based compo und. The exchange interaction between the Gd3+ local moments and the c onduction electrons (c-e) is c-e wave-vector dependent in both compoun ds.