  We predict from DFT based electronic structure calculations that a monolayer
made up of Carbon and Arsenic atoms, with a chemical composition (CAs3) forms
an energetically and dynamically stable system. The optimized geometry of the
monolayer is slightly different from the buckled geometric configuration
observed for silicene and germanene. The results of electronic structure
calculations predict that it is a semi-metal. Interestingly, the electronic
band structure of this material possesses a linear dispersion and a Dirac cone
at the Fermi level around the high symmetric K point in the reciprocal lattice.
Thus, at low energy excitation (up to 105 meV), the charge carriers in this
system behave as massless Dirac-Fermions. Detailed analysis of partial density
of state suggests that the 2pz orbital of C atoms plays vital role in
determining the nature of the states, which has a linear dispersion and hence
the Dirac cone, around the Fermi level. Thus, the electronic properties of CAs3
monolayer are similar to those of graphene and other group IV based monolayers.
In addition, we have also investigated the influence of mechanical strain on
the properties of CAs3 monolayer. The buckled configuration becomes the planar
configuration for a tensile strain beyond 18%. Our results indicate that the
monolayer possesses linear dispersion in the electronic band structure for a
wide range of mechanical strain from -12 to 20%, though the position of Dirac
point may not lie exactly at the Fermi level. The linear dispersion disappears
for a compressive strain beyond -12% & it is due to the drastic changes in the
geometrical environment around C atom. Finally, we wish to point out that CAs3
monolayer belongs to the class of Dirac materials where the behaviour of
particles, at low energy excitations, are characterized by the Dirac-like
Hamiltonian rather than the Schrodinger Hamiltonian.
