Carrier-mediated long-range ferromagnetism in electron-doped Fe-C ₄ and Fe-N ₄ incorporated graphene

Graphene magnetism has been proposed but based on thermodynamically unstable zigzag edges and dangling electrons with broken sublattice symmetry. From results of first-principles calculations, we propose a way to realize thermodynamically stable graphene ferromagnetism by seamlessly incorporating transition metals into the graphene honeycomb network. An Fe atom substituting a carbon-carbon dimer of graphene can result in nearly square-planar covalent bonding between the spin-polarized Fe 3d orbitals and graphene dangling bond states. Dangling bond passivation of the divacancy pore with N and O strongly affects the Fe incorporation into the graphene network in terms of energetics and electronic structure. The Fe-N ₄ or Fe-C ₄ incorporated graphene is predicted to show long-range ferromagnetism particularly due to carrier mediation when electron doped.