Fermi/non-Fermi mixing in SU($N$) Kondo effect

TL;DR

This paper investigates the SU(N) Kondo effect using conformal field theory, revealing a unique Fermi/non-Fermi mixing behavior at low temperatures and non-universal Wilson ratios for certain parameter regimes.

Contribution

It uncovers a novel Fermi/non-Fermi mixing phenomenon in SU(N) Kondo systems and shows the Wilson ratio's deviation from universality as an experimental signature.

Findings

Low temperature Fermi liquid behavior coexists with non-Fermi liquid IR fixed point.

Wilson ratio is non-universal for N > k > 1.

Fermi/non-Fermi mixing can be experimentally detected via Wilson ratio deviations.

Abstract

We apply conformal field theory analysis to the $k$-channel SU($N$) Kondo system, and find a peculiar behavior in the cases $N > k > 1$, which we call Fermi/non-Fermi mixing: The low temperature scaling is described as the Fermi liquid, while the zero temperature IR fixed point exhibits the non-Fermi liquid signature. We also show that the Wilson ratio is no longer universal for the cases $N > k > 1$. The deviation from the universal value of the Wilson ratio could be used as an experimental signal of the Fermi/non-Fermi mixing.