Phagraphene: A Low-energy Graphene Allotrope composed of 5-6-7 Carbon Rings with Distorted Dirac Cones

TL;DR

This paper introduces phagraphene, a new low-energy 2D carbon allotrope with 5-6-7 ring structures, exhibiting distorted Dirac cones and tunable electronic properties, promising for advanced material applications.

Contribution

The study presents the discovery and characterization of phagraphene, a novel carbon allotrope with unique structural and electronic features, using systematic evolutionary structure searching.

Findings

Phagraphene is energetically more favorable than many predicted 2D carbon allotropes.

It exhibits distorted Dirac cones with direction-dependent properties.

The electronic features are robust under external strain and can be tuned.

Abstract

Using systematic evolutionary structure searching we propose a new carbon allotrope, phagraphene, standing for penta-hexa-hepta-graphene, because the structure is composed of 5-6-7 carbon rings. This two-dimensional (2D) carbon structure is lower in energy than most of the predicted 2D carbon allotropes due to its sp2-hybridization and density of atomic packing comparable to graphene. More interestingly, the electronic structure of phagraphene has distorted Dirac cones. The direction-dependent cones are further proved to be robust against external strain with tunable Fermi velocities.