Quasi-Kondo Phenomenon due to Dynamical Jahn-Teller Effect

TL;DR

This paper proposes a non-magnetic Kondo effect mechanism arising from dynamical Jahn-Teller phonons in multiorbital systems, leading to quasi-Kondo behavior with potential relevance to filled skutterudites.

Contribution

It introduces a novel quasi-Kondo phenomenon driven by dynamical Jahn-Teller effects in multiorbital models, expanding understanding of non-magnetic Kondo effects.

Findings

Identification of a vibronic ground state with double degeneracy.

Observation of entropy release below a characteristic temperature.

Relevance to electronic properties of filled skutterudites.

Abstract

A mechanism of non-magnetic Kondo effect is proposed on the basis of a multiorbital Anderson model coupled with dynamical Jahn-Teller (JT) phonons. An electron system coupled dynamically with JT phonons has a vibronic ground state with double degeneracy due to clockwise and anti-clockwise rotational modes with entropy of $\log 2$. When a temperature is lower than a characteristic energy to turn the rotational direction, the rotational degree of freedom is eventually suppressed and the corresponding entropy $\log 2$ is released, leading to quasi-Kondo behavior. We discuss possible relevance of this quasi-Kondo phenomenon to electronic properties of filled skutterudites.