ω‐Graphene: A Graphene Allotrope with Desirable Auxeticity and Dirac Cone

Abstract A material generally contracts transversely when stretched along one direction. A few materials exhibit unusual auxeticity, which is rarely observed in planar two‐dimensional materials. Herein, a planar graphene allotrope ω‐graphene with a highly negative Poisson's ratio is proposed. ω‐Graphene possesses excellent mechanical properties and exhibits a unique highly negative Poisson's ratio of −0.17 along the crystallographic armchair direction, which is six times larger than that of graphene. Additionally, ω‐graphene exhibits intrinsic semimetallic characteristics with a Dirac cone located at 0.08 eV below the Fermi level. In particular, the Dirac cone of ω‐graphene persists throughout the entire strain range. A highly negative Poisson's ratio and semimetallic properties endow ω‐graphene with excellent potential for practical application to nanomechanical and nanoelectronic devices.