Kondo breakdown in a spin-1/2 chain of adatoms on a Dirac semimetal

TL;DR

This paper investigates the Kondo breakdown phenomenon in a spin-1/2 chain of adatoms on a Dirac semimetal, identifying a phase transition and critical point through theoretical and computational methods, with implications for experimental detection.

Contribution

It introduces a comprehensive analysis of Kondo breakdown in a spin chain coupled to Dirac fermions, combining RG, large-N, and QMC methods to reveal a new phase and critical behavior.

Findings

Existence of a Kondo-breakdown phase and critical point

Identification of a heavy Fermi liquid phase

Potential experimental signatures in tunneling conductance

Abstract

We consider a spin-1/2 Heisenberg chain coupled via a Kondo interaction to two-dimensional Dirac fermions. The Kondo interaction is irrelevant at the \textit{decoupled} fixed-point, leading to the existence of a Kondo-breakdown phase and a Kondo-breakdown critical point separating such a phase from a heavy Fermi liquid. We reach this conclusion on the basis of a renormalization group analysis, large-N calculations as well as extensive auxiliary-field quantum Monte Carlo simulations. We extract quantities such as the zero-bias tunneling conductance which will be relevant to future experiments involving adatoms on semimetals such as graphene.