Stabilization of ferromagnetic ordering in graphene-based systems up to room temperature remains an important challenge owing to the huge scope for applications in electronics, spintronics, biomedicine, and separation technologies. To date, several strategies have been proposed, including edge engineering, introduction of defects and dopants, and covalent functionalization. However, these techniques are usually hampered by limited temperature sustainability of ferromagnetic ordering. Here, we describe a method for the well-controlled sp3 functionalization of graphene to synthesize zigzag conjugated sp2 carbon chains that can act as communication pathways among radical motifs. Zigzag sp2/sp3 patterns in the basal plane were clearly observed by high-resolution scanning transmission electron microscopy and provided a suitable matrix for stabilization of ferromagnetic ordering up to room temperature due to combined contributions of itinerant π-electrons and superexchange interactions. The results highlight the principal role of sp2/sp3 ratio and superorganization of radical motifs in graphene for generating room-temperature nonmetallic magnets.
Keywords: 2D magnets; DFT calculations; density of states; fluorographene; hydroxofluorographene; hydroxyl; magnetic carbon; spintronics.