Investigation of the impact of a strain-induced pseudo-magnetic field on the magneto-optical absorption spectra of monolayer 8–Pmmn borophene

Abstract

The 8–$Pmmn$ borophene monolayer exhibits tilted and anisotropic Dirac energy dispersion cones. In this study, we theoretically investigate the magneto-optical absorption in the presence of a perpendicular static magnetic field and mechanical strain, which is treated as a pseudo-magnetic field under certain conditions. Using perturbation theory for a degenerate electron gas at low temperatures, we derive the magneto-optical absorption coefficient. Our results show that, in the absence of strain, Landau levels and absorption spectra in the K and $K^{\prime }$ valleys are identical, with no valley polarization. Valley polarization emerges only under strain and depends on the strain strength, external magnetic field, and tilt parameter. Notably, strain induces opposite shifts in the absorption spectra for the two valleys—redshift in the K valley and blueshift in the $K^{\prime }$ valley—while the absorption peak intensity changes accordingly. These findings suggest potential applications in valleytronics and strain-engineered optoelectronics.