Zig-Zag sp2 Carbon Chains Passing through sp3 Framework - A Driving Force toward Room Temperature Ferromagnetic Graphene.

Stabilization of ferromagnetic ordering in graphene-based systems up to room temperature remains an important challenge owing to 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 zig-zag conjugated sp2 carbon chains that can act as communication pathways among radical motifs. Zig-zag 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 super-organization of radical motifs in graphene for generating room temperature non-metallic magnets.