Two-Dimensional Honeycomb B₂Se with Orthogonal Lattice: High Stability and Strong Anisotropic Dirac Cone

The Dirac cone structure provides massless Fermions, ultrahigh carrier mobility, and many other novel features that are significant for massless and dissipationless quantum devices. The anisotropic Dirac cone has the advantage of anisotropic Fermi velocity and carrier mobility, which is different from the isotropic Dirac cone. Here we report two different configurations of B₂Se monolayers with anisotropic Dirac cones. Fully optimized B₂Se, as a rare two-dimensional pure planar pristine honeycomb structure, can maintain good structural integrity at higher temperatures up to 1000 K in ab initio molecular dynamics simulation, Young’s modulus and Poisson’s ratio show high anisotropy, the Fermi velocity of 10⁶m/s is the same order of magnitude as graphene. Moreover, we analyze the rationality of the existence of Dirac cones in the structure through wave functions and symmetry. This work provides novel candidates for finding direction-dependent, massless, and dissipationless quantum devices.