Robust Room Temperature Ferromagnetism In Cobalt Doped Graphene by Precision Control of Metal Ion Hybridization

Graphene-based magnetic materials exhibit novel properties and promising applications in the development of next-generation spintronic devices. Modern synthesis techniques have paved the way to design precisely the local environments of metal atoms anchored onto a nitrogen-doped graphene matrix. Herein, it is demonstrated that grafting cobalt (Co) into the graphene lattice induces robust and stable room-temperature ferromagnetism. These comprehensive experiments and first-principles calculations unambiguously identify that the mechanism for this unusual ferromagnetism is π-d orbital hybridization between Co d_xz and graphene p_z orbitals. Here, it is found that the magnetic interactions of Co–carbon ions are mediated by the spin-polarized graphene p_z orbitals, and room temperature ferromagnetism can be stabilized by electron doping. It is also found that the electronic structure near the Fermi level, which sets the nature of spin polarization of graphene p_z bands, strongly depends on the local environment of the Co moiety. This is the crucial, previously missing, ingredient that enables control of the magnetism. Overall, these observations unambiguously reveal that engineering the atomic structure of metal-embedded graphene lattices through careful d to p orbital interactions opens a new window of opportunities for developing graphene-based spintronics devices.