Kondo effect versus Jahn-Teller effect: A new class of quantum impurity problems

TL;DR

This paper explores the complex interplay between the Kondo effect and Jahn-Teller instability in orbitally degenerate impurity ions within metals, revealing a transition from perturbative regimes to a coherent state involving phonons and electrons.

Contribution

It introduces a new class of quantum impurity problems that combine Kondo and Jahn-Teller effects, analyzing their behavior across different coupling regimes.

Findings

Transition from perturbative to coherent phonon-electron states

Identification of a complex intermediate regime

Insights into impurity behavior in orbitally degenerate systems

Abstract

Impurity ions with orbitally degenerate ground electronic configuration embedded in metals are subjects to both the Kondo effect and the Jahn-Teller instability. While increasing the Jahn-Teller coupling, one passes, from the region of parameters where the perturbation theory is applicable, through a complicated intermediate region, to a region where phonons, localized electrons and conduction electrons form a coherent state.