Charge Kondo effect toward a non-Fermi-liquid fixed point in the orbitally degenerate exchange model

TL;DR

This paper demonstrates the existence of a new non-Fermi-liquid fixed point in an orbitally degenerate Kondo model, characterized by residual charge degrees of freedom and anomalous electric and thermal properties, distinct from traditional models.

Contribution

It introduces a novel non-Fermi-liquid fixed point in an orbitally degenerate Kondo model, highlighting unique residual charge effects and differences from previous models like Coqblin-Schrieffer.

Findings

Identification of a new non-Fermi-liquid fixed point

Residual charge degrees lead to multi-channel Kondo effect

Anomalous electric and thermal behaviors observed

Abstract

We show that a Kondo-type model with an orbital degeneracy has a new non-Fermi-liquid fixed point. Near the fixed point the spin degrees of freedom are completely quenched, and the residual charge degrees of freedom lead to the multi-channel Kondo effect. Anomalous behavior appears in electric and thermal properties, but the magnetic susceptibility should show the local Fermi-liquid behavior. The non-Fermi-liquid fixed point becomes unstable against perturbations breaking the particle-hole symmetry. We derive these results using the third-order scaling for a spherically symmetric model with a fictitious spin. In contrast to the Coqblin-Schrieffer model, the present model respects different time-reversal properties of multipole operators.