Electric field manipulation of multiple nonequivalent Dirac cones in the electronic structures of hexagonal CrB4 sheet**Project supported by the National Natural Sciences Foundation of China (Grant Nos. 11704294 and 11504281), the Natural Science Foundation of Hubei Province, China (Grant No. 2016CFB586), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 2017IVA078, 2018IVB017, 2017IB013, 2018IB009, and 2018IB011).

Abstract

Two-dimensional materials with Dirac cones have significant applications in photoelectric technology. The origin and manipulation of multiple Dirac cones need to be better understood. By first-principle calculations, we study the influence of external fields on the electronic structure of the hexagonal CrB4 sheet with double nonequivalent Dirac cones. Our results show that the two cones are not sensitive to tensile strain and out-of-plane electric field, but present obviously different behaviors under the in-plane external electric field (along the B–B direction), i.e., one cone holds while the other vanishes with a gap opening. More interestingly, a new nonequivalent cone emerges under a proper in-plane electric field. We also discuss the origin of the cones in CrB4 sheet. Our study provides a new method on how to obtain Dirac cones by the external field manipulation, which may motivate potential applications in nanoelectronics.