Hydrogen-induced magnetism in graphene: a simple effective model description

TL;DR

This paper presents a simple effective Anderson impurity model that accurately describes hydrogen-induced magnetism in graphene, capturing experimental phenomena and behaviors of hydrogen dimers with various configurations.

Contribution

The paper introduces a straightforward Anderson impurity model with an effective Coulomb interaction to explain hydrogen-induced magnetism in graphene, simplifying previous complex descriptions.

Findings

The model reproduces experimental magnetic behaviors of hydrogen adatoms on graphene.

It accurately describes the effects of Coulomb interactions on impurity resonance states.

The model applies well to various hydrogen adsorption configurations.

Abstract

Hydrogen adatoms induced magnetic moment on graphene has been observed in atomic scale in a recent experiment [Gonzalez-Herrero et al., Science 352, 437 (2016)]. Here, we demonstrate that all the experimental phenomena can be simply and well described by an equivalent Anderson impurity model, where the electronic correlations on both carbon and hydrogen atoms are represented by an effective on-site Coulomb interaction on hydrogen adatom $U_H$. This simple equivalent model works so well is because that the main effect of Coulomb interaction on both carbon and hydrogen atoms is just to split the impurity resonance states with different spin. This effective Anderson impurity model can also well reproduce all the behaviours of hydrogen dimer on graphene observed in experiment. We thus argue that it should be a general model to describe the hydrogen adatoms on graphene with various adsorption configurations, especially for their magnetic properties.