Kondo impurity on the honeycomb lattice at half-filling

TL;DR

This paper models a Kondo impurity on a honeycomb lattice like graphene, deriving an effective theory and analyzing critical couplings, magnetic susceptibility, and specific heat considering Coulomb interactions.

Contribution

It derives a continuum theory for a Kondo impurity on a honeycomb lattice and analyzes its critical properties including Coulomb interaction effects.

Findings

Reduced to a single-coupling pseudogap Kondo model under certain conditions

Calculated critical coupling in large-N expansion

Analyzed magnetic susceptibility and specific heat with Coulomb effects

Abstract

We consider a Kondo-like impurity interacting with fermions on a honeycomb lattice at half-filling, as in the case of graphene. We derive from the lattice model an effective one-dimensional continuum theory which has, in general, four flavors with angular momentum mixing in the presence of internode scattering processes and six couplings in the spin-isotropic case. Under particular conditions, however, it can be reduced to a single-coupling multichannel pseudogap Kondo model. We finally calculate, in the presence of an energy dependent Fermi velocity, induced by Coulomb interaction, the critical coupling in the large-N expansion, the magnetic susceptibility and the specific heat.