Spin interactions in decorated graphene nanoflakes with two localized spin-1/2 entities

Magnetic properties of graphene nanoflakes with designed edge shapes are theoretically analyzed by means of the first-principles calculation. As a starting point, we take a nanoflake with decorated zigzag edges where no magnetism is expected. Then, it is shown that removal of one decoration unit induces a well-defined localized spin-1/2 state. When two decoration units are removed, there arise two localized spin-1/2 states. Notably, when two spins are aligned in the same edge, the spin-spin interaction is ferromagnetic, while when two spins are aligned in the opposite edges, the spin-spin interaction is antiferromagnetic. This suggests that decorated nanoflakes form a promising playground for nanoscale spin devices with tunable spin-spin interactions by designing edge shapes. • Graphene nanoflakes hosting two spin-1/2 entities are theoretically proposed. • Nanostructure dependence of the spin-spin interactions is derived with the first-principles calculation. • The proposed nanoflakes can form a foundation for molecular spin devices.