Raman scattering spectra of bismuthene: A first-principles prediction

Recently, bismuthene is predicted a room-temperature quantum spin Hall materials, which can conduct dissipationless charge and spin current via the symmetry-protected gapless surface states, and has generated intensive research interest in condensed matter. In order to study the unique properties of ultrathin film, Raman spectroscopy is considered to be the simple detection methods. Herein, we systematically examined the evolution of frequencies and Raman peaks of phonon modes in bismuthene according to the various strain and layer number conditions. Due to the weakening of bond energy under different strains, the biaxial strains lead to clearer frequency shifts than that of uniaxial strains and also make the relative Raman intensity of in-plane modes be higher than that of out-of-plane. Meanwhile, it is important that there are new peaks of Raman scattering spectra in the multilayer structures, corresponding to the shear mode and breathing mode, whose vanish in Raman scattering spectra can detect the monolayer structure. The present results have guiding significance for the experiments of bismuthene.