Dirac Semimetals in Homogeneous Holey Carbon Nitride Monolayers

In this work, we propose four novel holey carbon nitride monolayer C7N3, C10N3, C13N3, and C19N3 stoichiometries intriguingly behaving as ideal 2D Dirac semimetals whose Dirac cones are rightly located at the Fermi level. Moreover, the results of Gibbs free energies, phonon dispersions, ab initio molecular dynamics, and linear elastic constants indicate that their stabilities are comparable with the already-synthesized 2D carbon nitride materials. The Dirac cones of the systems originate from the hopping between all pz orbitals of the C and N atoms. The theory of elementary band representation indicates that the Dirac cones of the systems come from the time-reversal forced twofold degeneracy at K and K′ points. Furthermore, we find that the Dirac cones of the systems are robust against the spin–orbit coupling and external strain. Considering their excellent conductivity as Dirac semimetals, the four holey carbon nitride monolayers are potential candidates for the applications in future high-performance electronic devices.