Magnetic correlation effects by the topological zero mode in a hydrogenated graphene vacancy $V_{111}$

TL;DR

This paper theoretically investigates the electron correlation effects caused by the topological zero mode in hydrogenated graphene vacancies, revealing the emergence of the Kondo effect due to anti-ferromagnetic screening.

Contribution

It introduces a Kondo model derived from density functional theory for hydrogenated graphene vacancies, highlighting the role of the zero mode in electron correlations and Kondo physics.

Findings

Finite on-site correlation energy allows zero mode half-filling and spin formation.

Anti-ferromagnetic Kondo screening dominates in dilute vacancy limit.

Kondo effect is expected at low temperatures due to two-body interactions.

Abstract

Electron correlation effects caused by the topological zero mode of a hydrogenated graphene vacancy, $V_{111}$, with three adsorbed hydrogen atoms is discussed theoretically. A Kondo model is derived from the multi-reference representation of the density functional theory, where exchange scattering processes between the zero mode and low-energy modes in the Dirac cones are estimated. Even when the Dirac cone is slightly off from the charge neutral point, a finite on-site correlation energy, $U_0$, for the zero mode of an isolated $V_{111}$ allows the half-filling of the localized level giving a spin $s=1/2$. The anti-ferromagnetic Kondo screening mediated by higher order scattering processes becomes dominant in the dilute limit of the vacancies. Our estimation of relevant two body interactions certifies appearance of the Kondo effect at low temperatures.