A suspended layer made up of ferromagnetically ordered spins could be created between two- monolayer or multilayer graphene through intercalation. Stability and electronic structure studies show that, when fluorine molecules are intercalated between two mono/multilayer graphene, their bonds get stretched enough $(\sim 1.9\text{–}2.0\AA )$ to weaken their molecular singlet eigenstate. Geometrically, these stretched molecules form a pseudoatomized fluorine layer by maintaining a van der Waals separation of $\sim 2.6\AA$ from the adjacent carbon layers. As there is a significant charge transfer from the adjacent carbon layers to the fluorine layers, a mixture of triplet and doublet states stabilizes to induce local spin moments at each fluorine site and in turn form a suspended two-dimensional spin lattice. The spins of this lattice align ferromagnetically with nearest-neighbor coupling strength as large as $\sim 100\mathrm{meV}$. Our finite-temperature ab initio molecular dynamics study reveals that the intercalated system can be stabilized up to a temperature of 100 K with an average magnetic moment of $\sim 0.6{\mu }_B/\mathrm{F}$. However, if the graphene layers can be held fixed, the room-temperature stability of such a system is feasible.

• Received 9 February 2020
• Accepted 19 June 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.074411