Kondo scaling in the optical response of YbIn1-xAgxCu4.

Theoretical work on Kondo systems predicts universality in the scaling of observable quantities with the Kondo temperature, T(K). Here we report infrared-frequency optical response measurements of the correlated system YbIn(1-x)AgxCu4. We observe that x-dependent variations in the frequency and strength of a low-energy excitation are related to the x-dependent Kondo temperature. Comparison of the inferred trends with existing theory and a model calculation provides a framework in which to view these experimental results as scaling phenomena arising from local-moment/conduction electron hybridization.