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

TL;DR

This paper explores how exciton effects and Kondo scattering interplay in intermediate valence and Kondo systems, revealing a marginal regime with temperature-dependent Kondo temperature that could explain experimental anomalies.

Contribution

It introduces a modified scaling theory incorporating exciton effects, showing significant deviations from the standard Anderson model in heavy fermion systems.

Findings

Identification of a marginal regime with temperature-dependent Kondo temperature

Demonstration of altered scaling behavior due to exciton effects

Potential explanation for experimental controversies in heavy fermion systems

Abstract

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 fermion and related systems.