A unified geometric rule for designing nanomagnetism in graphene

Abstract

Based on the underlying graphene lattice symmetry and an itinerant magnetism model on a bipartite lattice, we propose a unified geometric rule for designing graphene-based magnetic nanostructures: spins are parallel (ferromagnetic (FM)) on all zigzag edges which are at angles of 0 degrees and 120 degrees to each other, and antiparallel (antiferromagnetic (AF)) at angles of 60 degrees and 180 degrees. The rule is found to be consistent with all the systems that have been studied so far. Applying the rule, we predict several novel graphene-based magnetic nanostructures: 0-D FM nanodots with the highest possible magnetic moments, 1-D FM nanoribbons, and 2-D magnetic superlattices.