Defect-Induced Kondo Effect in graphene: Role of Localized State of $\pi$ Electrons

TL;DR

This paper investigates how localized π orbitals around defects in graphene influence the defect-induced Kondo effect, revealing their role in the temperature sensitivity and magnetic response of the phenomenon through numerical and theoretical analysis.

Contribution

It demonstrates that localized π orbitals assist the Kondo effect in graphene and explores their magnetic field dependence, providing insights into the magnetic sensitivity of the Kondo effect in defective graphene.

Findings

Localized π orbitals enhance the Kondo effect in graphene.

The Kondo temperature depends on the broadening of the localized π orbital.

The spectral width of the π orbital increases with magnetic field, affecting the Kondo temperature.

Abstract

We discuss a role of the localized $\pi$ orbital, which exists around the defect, on the defect-induced Kondo effect in graphene by a numerical renormalization group study. We find that the localized $\pi$ orbital assists this Kondo effect, and the Kondo temperature is sensitive to the broadening of the localized $\pi$ orbital. Secondly, we focus on the negative magnetoresistance of this Kondo effect. In the experimental result, it has been shown that the negative magnetoresistance is ten times larger than the usual Kondo effect. In order to clarify the mechanism of the "magnetic sensitive" Kondo effect, as a first step, we study an orbital magnetic field dependence of the localized $\pi$ orbital by a tight-binding model with a Peierls phase. We find that as the magnetic field increases, the spectral width of the localized $\pi$ orbital increases and the local DOS at the Fermi level decreases. Since the Kondo temperature is strongly dependent of the broadening of the localized $\pi$ orbital, it is expected that this Kondo effect is sensitive to the orbital magnetic field as observed in the experiment.