Bicircular laser field controlling spin-valley optical conductivity in buckled hexagonal lattice under strain

A two-dimensional hexagonal lattice features an additional degree of freedom, analogous to spin, arising from the K and K′ valleys in the Brillouin zone. These valleys offer promising opportunities for logic operations in quantum information processing, operating on few-femtosecond timescales. In this work, we develop a model to investigate the electronic and optical properties governing topological phases induced by a bicircular laser field. Our findings reveal that spin polarization emerges when the laser field orientation aligns with the lattice symmetry, giving rise to a non-zero quantum anomalous Hall effect due to time-reversal symmetry breaking. This effect is driven by the bicircular laser. Additionally, we introduce uniaxial strain along the armchair direction to induce anisotropy in electron transport. Analytical evaluations demonstrate that the constraint condition relating the longitudinal conductivities, σ_xx(ω) and σ_yy (ω), becomes strain-dependent. However, the DC transverse conductivity remains insensitive to strain. The valley degree of freedom can be distinguished through the sign of the Faraday angle. Notably, the analytical expressions presented in this work also imply that the fine-structure constant may be extracted via transmittance and Faraday rotation measurements.