Electron spin resonance investigation of ultra-small double walled carbon nanotubes embedded in zeolite nanochannels

Zigzag sp2 Carbon Chains Passing through an 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 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.