Spin and valley-polarized Faraday rotation in irradiated buckled Xene materials

This study delves into the theoretical exploration of Faraday rotation and ellipticity in light beams transmitted through buckled Xene materials. These materials undergo topological phase transitions (TPTs), shifting from topologically non-trivial to trivial systems under the influence of an off-resonance irradiated laser field or a staggered electric potential. Specifically, we investigate the manifestation of these phenomena when the buckled Xene material is exposed to an off-resonant laser and staggered sublattice potential. Using the Kubo formula, we derive the optical conductivities of the buckled Xene material to analyze transmission spectra through Fresnel’s transmission coefficients. Additionally, we calculate the spin and valley-dependent Faraday rotation angles and ellipticities of the buckled Xene by selecting suitable parameters for the circularly polarized off-resonant laser field and staggered electric potential across distinct topological quantum phases. Our findings reveal a high sensitivity of Faraday rotation and ellipticity to the topological invariants. In particular, we find that due to the broken time-reversal symmetry (TRS), the amount of the maximum spin and valley polarized Faraday rotation angle and ellipticity in irradiated buckled Xene material without magnetic field are ≊±0.53 ∘ and ≊±0.2 ∘ , respectively. Our results suggest possible techniques for probing topological numbers and topological phase transitions in buckled Xene materials by Faraday rotation.