Theory of Defect-Induced Kondo Effect in Graphene: Effect of Zeeman Field

TL;DR

This paper investigates how a Zeeman field influences the defect-induced Kondo effect in graphene, revealing an unusual fixed point with unique entropy and spin properties through numerical analysis.

Contribution

It introduces a theoretical model for the Zeeman field's impact on the Kondo effect in graphene and analyzes it using numerical renormalization group methods.

Findings

Identification of an unusual fixed point at the boundary of spin polarized and Kondo-Yosida states

Discovery of a defect entropy of k_B ln2 at the fixed point

Observation of an expectation value of S_z^2 equal to 1/8

Abstract

The effect of the Zeeman field on the defect-induced Kondo effect in graphene is investigated. The effective model of the Kondo effect is derived, and is analyzed on the basis of the numerical renormalization group method. It is found that, under the Zeeman field, at the border of the spin polarized state and the Kondo-Yosida singlet state, there is an unusual fixed point where the entropy of the defect is k_B ln2 and the expectation value of S^2_z is 1/8.