A novel carbon–nitrogen Dirac semimetal C5N4 monolayer

Abstract

Two-dimensional (2D) carbon–nitrogen materials have aroused a lot of interest due to their amazing performance and possible uses. However, only a few of them have been discovered to have semimetallic properties. Based on first-principles calculations, we predict a unique 2D Dirac semimetal C 5 N 4 with stable thermodynamics, dynamics, and mechanics. The Dirac cones in the system are rightly located at the Fermi level, and they are mostly contributed by the p z orbitals of C and N atoms. By examining the irreducible representations of related Bloch states, we discover that they are protected by the σ υ ( x ) and C 2 z symmetries. In addition, we establish a k ⋅ p model and an 18-band tight-binding (TB) model to investigate the formation and properties of Dirac points. Furthermore, we find that the Dirac points are robust to external strains. Finally, we propose a method for synthesizing this material. The C 5 N 4 monolayer is a novel potential material for high-performance electronic devices in the future.