Band structure of borophene

Borophene is one of the latest elemental two-dimensional material realized experimentally [Mannix et al., Science 350, 1515 (2015); Feng et al., PRL 118, 096401 (2017)]. The band structure of the 8-Pmmn structure has been studied using ab initio techniques, revealing the presence of Dirac cones and ionicity in the bonds [Lopez-Bezanilla and Littlewood, PRB 93, 241405 (R) (2016)]. We present a k.p theory of the band structure in order to reveal electronic properties determined by symmetry, including in the presence of external perturbations such as strain and electric and magnetic fields. Comparison to phosphorene [ L. C. Lew Yan Voon, A. Lopez-Bezanilla, J. Wang, Y. Zhang and M. Willatzen, New J. Phys. 17, 025004 (2015)], another orthorhombic two-dimensional material, is given.