A two-dimensional magnetic carbon allotrope of hexagonally arranged fused pentagons

Abstract

A two-dimensional magnetic carbon allotrope of hexagonally arranged fused pentagons is theoretically predicted through the copolymerization of benzene and spiro[4.4]nonatetraene. The hexagonal spiro-graphene has ferromagnetic and antiferromagnetic phases as its respective ground and metastable states, the two states being almost degenerate in energy because the Dirac band at the Fermi level is narrow. The polarized electron spin is distributed throughout a hexagonal network of three-fold coordinated C atoms surrounded by four-fold coordinated C atoms. The sheet of these coordinated C atoms also possesses an electrostatic polarization normal to the atomic layer because the atomic arrangement along this direction is asymmetric.