Deconstruction of the Kondo Effect near the AFM-Quantum Critical Point

TL;DR

This paper investigates the behavior of a magnetic impurity near an antiferromagnetic quantum critical point, revealing new fixed points and the persistence of spin-fluctuation coupling despite the disappearance of Kondo screening.

Contribution

It introduces a novel multichannel Kondo fixed point that does not require channel isotropy, advancing understanding of quantum criticality in heavy-fermion systems.

Findings

Discovery of a new stable fixed point without channel isotropy

Kondo screening vanishes at the fixed point

Coupling to spin-fluctuations persists at the critical point

Abstract

The problem of a spin-1/2 magnetic impurity near an antiferromagnetic transition of the host lattice is solved. The problem is shown to transform to a multichannel problem. A variety of fixed points is discovered asymptotically near the AFM-critical point. Among these is a new variety of stable fixed point of a multichannel Kondo problem which does not require channel isotropy. At this point Kondo screening disappears but coupling to spin-fluctuations remains. Besides its intrinsic interest, the problem is an essential ingredient in the problem of quantum critical points in heavy-fermions.