Insight into the robust multiple Dirac-cones in perovskite R3¯c phase CuBO3 semimetal from first-principles.

Motivated by a related recent study (Jiao et al. PRL 119, 016403 (2017)), in this work, a new R3¯c type semimetal has been calculated based on the first-principles method. We observed that CuBO3 showed robust multiple Dirac-cones (DCs) near the Fermi level. Also, we found that these DCs were coming from the hybridization between O-p and Cu-d orbits. As a medium state between normal insulating state and topological insulating state, Dirac semimetal is a new class of materials due to its novel physical properties. Moreover, for CuBO3, the Dirac-like band crossings are dispersed in a linear pattern across a very large energy range. In order to guide the experiment, the thermal stability of CuBO3 has been studied through ab initio molecular dynamic simulations. Finally, we are keen to emphasize that the specific space of this group allows for the three-dimensional Dirac point to be used as a symmetric protection for degeneracy. There may be many other three-dimensional Dirac semimetals in the R3¯c phase of crystallization that have not yet been discovered. Thus, more attention to these materials is required in the future.