Hidden Integrability of a Kondo Impurity in an Unconventional Host

TL;DR

This paper demonstrates that a spin-1/2 Kondo impurity in unconventional hosts with vanishing density of states can be exactly solved using Bethe ansatz, revealing hidden integrability despite nonlinear band dispersion.

Contribution

It proves the hidden integrability of the Kondo model in gapped and gapless unconventional hosts and provides an exact solution via Bethe ansatz.

Findings

Exact diagonalization of the model using Bethe ansatz.

Identification of hidden integrability in nonlinear band systems.

Applicability to systems with vanishing density of states.

Abstract

We study a spin-1/2 Kondo impurity coupled to an unconventional host in which the density of band states vanishes either precisely at (``gapless'' systems) or on some interval around the Fermi level (``gapped''systems). Despite an essentially nonlinear band dispersion, the system is proven to exhibit hidden integrability and is diagonalized exactly by the Bethe ansatz.