Localized Spins on Graphene

TL;DR

This paper investigates magnetic impurities on graphene using numerical renormalization group methods, revealing spin-dependent scattering, potential for spin-polarized currents, and Kondo screening effects at low temperatures.

Contribution

It provides a detailed analysis of impurity-induced magnetic and transport properties in graphene, highlighting spin-dependent scattering and magnetoresistance effects.

Findings

Impurity scattering becomes strongly spin dependent.

Spin polarized currents can be injected using STM.

Kondo screening occurs at low temperatures in gated graphene.

Abstract

The problem of a magnetic impurity, atomic or molecular, absorbed on top of a carbon atom in otherwise clean graphene is studied using the numerical renormalization group. The spectral, thermodynamic, and scattering properties of the impurity are described in detail. In the presence of a small magnetic field, the low energy electronic features of graphene make possible to inject spin polarized currents through the impurity using a scanning tunneling microscope (STM). Furthermore, the impurity scattering becomes strongly spin dependent and for a finite impurity concentration it leads to spin polarized bulk currents and a large magnetoresistance. In gated graphene the impurity spin is Kondo screened at low temperatures. However, at temperatures larger than the Kondo temperature, the anomalous magnetotransport properties are recovered.