Effect of In-Plane Biaxial Strain on the Dirac Cone in α-Graphyne and Band Gap in α-BNyne

Abstract

Effects of strain on the electronic properties of α-graphyne and its BN analogues (α-BNyne) are investigated using density functional theory. It can be observed that, for both α-graphyne and α-BNyne sheets, under biaxial strain, the triple bonds show an insignificant change while the single bonds rise substantially. The band gap of α-BNyne decreases with in-plane biaxial strain. For α-graphyne under tensile strain, two linear bands cross at the Fermi level, the band energies still degenerate near the Fermi level and there is no shift in the position of Dirac points. Also, the tensile strain decreases the slope of the linear band. The results show that the in-plane biaxial strains do not affect the contribution of the out-of-plane pz orbitals for the Dirac cone. This insensitivity of the Dirac cone to such structural deformation suggests that α-graphyne is a promising two-dimensional material for future flexible electronic devices at the nanoscale.