Electric field driven magnetic phase transition in graphene nanoflakes

Within the framework of Hubbard model, a bowtie-shaped graphene nanoflake is identified to undergo an electric-field induced phase transition from an antiferromagnetic ground state. Unlike the case of half-metallic graphene nanoribbons, the electric field here leads to a non-magnetic state instead of ferromagnetic state after destructing the antiferromagnetic ordering. Because the spin is polarized on different sublattices of the nanodot in the antiferromagnetic phase, the transition occurs when the applied field breaks the sublattice symmetry and induces enough energy splitting among the originally degenerate zero-energy states. (C) 2013 AIP Publishing LLC.