Universal scaling in the dynamical conductivity of heavy fermion Ce and Yb compounds

Dynamical conductivity spectra [sigma(omega)] have been measured for many heavy-fermion (HF) Cc and Yb compounds. A characteristic excitation peak has been observed in the infrared region of sigma(omega) for all the compounds, and has been analyzed in terms of a simple model based on conduction (c)-f electron hybridized band. A universal scaling is found between the observed peak energies and the estimated c-f hybridization strengths of these HF compounds. This scaling demonstrates that the model of c-f hybridized band can generally and quantitatively describe the low-energy charge excitations in a wide range of HF compounds.