Competition for graphene: graphynes with direction-dependent Dirac cones

Phys Rev Lett. 2012 Feb 24;108(8):086804. doi: 10.1103/PhysRevLett.108.086804. Epub 2012 Feb 24.

Abstract

The existence of Dirac cones in the band structure of two-dimensional materials accompanied by unprecedented electronic properties is considered to be a unique feature of graphene related to its hexagonal symmetry. Here, we present other two-dimensional carbon materials, graphynes, that also possess Dirac cones according to first-principles electronic structure calculations. One of these materials, 6,6,12-graphyne, does not have hexagonal symmetry and features two self-doped nonequivalent distorted Dirac cones suggesting electronic properties even more amazing than that of graphene.