Giant magneto-optical Faraday and Kerr effects in 8- monolayer Floquet borophene
Phys. Rev. B 113, 245403 – Published 1 June, 2026
DOI: https://doi.org/10.1103/7v1b-xbhc
Abstract
We systematically investigate the magneto-optical transport and the associated Faraday and Kerr rotations in 8-Pmmn monolayer borophene subjected to a perpendicular magnetic field and off-resonant Floquet driving. The interplay between Floquet band engineering, Landau quantization, and optical selection rules leads to distinct features in the magneto-optical response. In particular, the real part of the longitudinal magneto-optical conductivity exhibits a series of resonance peaks arising from optically allowed intra- and inter-Landau-level transitions, whereas the Hall conductivity is dominated by a single pronounced resonance peak associated with the lowest cyclotron-like transition. Consistently, the complex reflectivity spectra for right- and left-circularly polarized light display analogous structures: their real parts contain multiple resonant peaks reflecting the longitudinal response, while their imaginary parts show a single dominant resonance peak with opposite phases originating from the Hall contribution. As a consequence of the resulting circular birefringence and dichroism, the Faraday and Kerr rotation angles exhibit similar resonance characters but opposite spectral phases, reflecting the different electromagnetic boundary conditions of transmission and reflection geometries. These findings indicate that the combined effects of magnetic-field-induced Landau quantization and Floquet band engineering provide an efficient pathway to control magneto-optical responses in borophene, revealing its potential for tunable two-dimensional magneto-optical and optoelectronic devices.
