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

Abstract

Hydrogen adatoms induced magnetic moment on graphene has been observed in atomic scale in a recent experiment [González-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 UH . 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.

Local magnetic moment oscillation around an Anderson impurity on graphene

“…2(e)]. Note that, the local magnetic moment on sublattice A is very tiny, and an obvious decay of local magnetic moment can only be found on sublattice B. Interestingly, this sublattice dependent magnetic moment decay is very like the one observed in the recent STM experiment [37,38], where obvious local magnetic moment decay is only found on sublattice B around a hydrogen impurity. The corresponding charge density variation ∆n i is also given in Fig.…”

“…Our theory may offer some new understanding to the recent STM experiment about the hydrogen impurity on graphene [37]. In our recent work [38], we have illustrated that, for a hydrogen impurity on graphene, the effect of Coulomb interaction on both impurity and carbon atoms can be equivalently represented by an effective on-site U of the hydrogen impurity. From this point of view, in addition to the half filling case, it is reasonable to expect that local magnetic moment oscillation on both sublattice can be found around the hydrogen adatom with finite doping.…”

“…A recent STM experiment shows that a hydrogen impurity can induce atomically modulated spin texture in graphene around it, which extents several nanometers away from the hydrogen impurity [37]. In our recent paper [38], we have illustrated that the hydrogen adatom on graphene can be effectively viewed as an Anderson impurity, though the Coulomb interaction on carbon atoms plays an important role in making the local magentism around the adatom. To the best of our knowledge, there is still no a detailed analysis about the Anderson impurity induced FO and quasiparticle interference (QPI) in graphene, despite some interesting phenomena have been observed in experiment.…”

“…It is reasonable because that, when the Anderson impurity is magnetic, it can be viewed as an spin dependent local potential. Actually, in the presence of a magnetic Anderson impurity, electrons with up and down spin on graphene will form their own resonance states at different energy [27,38,[48][49][50][51].…”