Two-dimensional carbon materials with an anisotropic Dirac cone: high stability and tunable Fermi velocity.

Among two-dimensional (2D) materials, Dirac-cone materials have attracted much attention due to their extraordinary electrical properties. In this work, we propose a new 2D carbon allotrope, 2D 2, which consists of 5-, 6-, 7- and 11-membered rings, and all carbon atoms are in one plane. Phonon dispersion curve calculations indicate that 2D 2 is kinetically stable under ambient conditions. First-principles molecular dynamics simulations show that 2D 2 has excellent thermal stability, even up to 3000 K. Of most interest are the electronic properties of the 2 structure: it is a Dirac semimetal with highly anisotropic Dirac cones, and its Fermi velocity is of the same order of magnitude as that of graphene. Furthermore, the structure exhibits strain self-doping properties and an in-plane strain-tunable Fermi velocity. The structure of 2 reported here shows great application potential in future electronic products.