Magnetization profile for impurities in graphene nanoribbons

TL;DR

This study investigates how transition-metal doping affects the magnetic properties of graphene nanoribbons, revealing that impurity-induced magnetism is more stable against edge disorder than edge-state magnetism.

Contribution

It provides a detailed analysis of impurity location effects on magnetization in doped GNRs using Hubbard and DFT methods, highlighting enhanced robustness of impurity-induced magnetism.

Findings

Impurity location significantly influences magnetic moments in GNRs.

Magnetic moments of dopants are stable despite edge disorder.

Impurity-induced magnetism is more robust than edge-state magnetism.

Abstract

The magnetic properties of graphene-related materials and in particular the spin-polarised edge states predicted for pristine graphene nanoribbons (GNRs) with certain edge geometries have received much attention recently due to a range of possible technological applications. However, the magnetic properties of pristine GNRs are not predicted to be particularly robust in the presence of edge disorder. In this work, we examine the magnetic properties of GNRs doped with transition-metal atoms using a combination of mean-field Hubbard and Density Functional Theory techniques. The effect of impurity location on the magnetic moment of such dopants in GNRs is investigated for the two principal GNR edge geometries - armchair and zigzag. Moment profiles are calculated across the width of the ribbon for both substitutional and adsorbed impurities and regular features are observed for zigzag-edged GNRs in particular. Unlike the case of edge-state induced magnetisation, the moments of magnetic impurities embedded in GNRs are found to be particularly stable in the presence of edge disorder. Our results suggest that the magnetic properties of transition-metal doped GNRs are far more robust than those with moments arising intrinsically due to edge geometry.