Superconductivity in charge Kondo systems

TL;DR

This paper develops a theoretical framework for understanding superconductivity in charge Kondo systems, focusing on how charge fluctuations and impurities influence superconducting properties and transition temperatures.

Contribution

It introduces a novel theory describing superconductivity induced by charge Kondo impurities and explores their effects on pairing and impurity interactions.

Findings

Superconductivity can be induced by charge Kondo impurities.

Charge Kondo centers enhance superconducting pairing.

Implications for Tl-doped PbTe as a charge Kondo superconductor.

Abstract

We present a theory of superconductivity in charge Kondo systems, materials with resonant quantum valence fluctuations, in the regime where the transition temperature is comparable to the charge Kondo resonance. We find superconductivity induced by charge Kondo impurities, study how pairing of a superconducting host is enhanced due to charge Kondo centers and investigate the interplay between Kondo-scattering and inter-impurity Josephson coupling. We discuss the implications of our theory for Tl-doped PbTe, which has recently been identified as a candidate charge Kondo system.