  The newly synthesized two-dimensional polyaniline (C3N) is structurally
similar to graphene, and has interesting electronic, magnetic, optical, and
thermal properties. Motivated by the fact that point defects in graphene give
rise to interesting features, like magnetization in an all carbon material, we
perform density functional theory calculations to investigate vacancy and
Stone-Wales type point defects in monolayer C3N. We compare and contrast the
structural, electronic and magnetic properties of these defects with those in
graphene. While monovacancies and Stone-Wales defects of C3N result in
reconstructions similar to those in graphene, divacancies display dissimilar
geometrical features. Different from graphene, all vacancies in C3N have
metallic character because of altered stoichiometry, those which have
low-coordinated atoms have finite magnetic moments. We further investigate the
robustness of the reconstructed structures and the changes in the magnetic
moments by applying tensile and compressive biaxial strain. We find that, with
the advantage of finite band gap, point defects in C3N are qualified as good
candidates for future spintronics applications.
