Evidence for the negative s-f interaction in a noble metal host

Electrical resistivity measurements on dillute alloys of Ce, Gd and Yb in Au are reported. Both Ce and Gd alloys show negligible temperature dependence in their excess resistivity at low temperatures whereas the Kondo effect is unambigously observed in the case of $\text{Au}\text{Yb}$. This result correlates with a negative exchange constant found for $\text{Au}\text{Yb}$ in the EPR experiment of Tao and co-workers.