Exciton effects in a scaling theory of intermediate valence and Kondo systems

An interplay of the Kondo scattering and exciton effects ($d-f$ Coulomb interaction) in the intermediate valence systems and Kondo lattices is demonstrated to lead to an essential change of the scaling behavior in comparison with the standard Anderson model. In particular, a marginal regime can occur where characteristic fluctuation rate is proportional to flow cutoff parameter. In this regime the “Kondo temperature” itself is strongly temperature dependent which may give a key to the interpretation of controversial experimental data for heavy fermions and related systems.