Optical redshift and blueshift spectra in monolayer β12 -borophene: Inversion symmetry breaking effects

Abstract

We have calculated the optical conductivity of monolayer ${\ensuremath{\beta}}_{12}$-borophene in the presence of an inversion symmetry breaking (ISB) field. We theoretically formulate such a field to effectively be induced by a substrate through an orbital hybridization effect in the experimental growth process. In the electronic band structure, the effect of the ISB field on the anisotropic dispersion appears as a perturbed manipulation of the energy scale. Different orientations of dispersion of triplet and Dirac fermions in ${\ensuremath{\beta}}_{12}$-borophene cause anisotropic optical interband transitions. Simulated ISB-induced optical conductivity using the Kubo formula produces various optical redshift and blueshift spectra. The longitudinal (Hall) component of optical conductivity presents a pure redshift (blueshift) spectrum with the ISB field, whereas the coexistence of both redshift and blueshift spectra emerge for the transverse component. This paper is a handful for practical applications in two-dimensional-based optoelectronic devices.