We theoretically study the photoinduced topological phase transition of black phosphorene induced by laser light with moderate intensity, which can satisfy the experimentally realistic requirement to preserve the quality of the sample. By deriving the effective Floquet Hamiltonian in terms of pseudospin $S=1/2$ degrees of freedom, we calculate the Chern number and the optical conductivity of the system with varying laser frequency $\mathrm{\Omega }$. As one can expect from the photon-assisted transport, the longitudinal optical conductivity has a threshold frequency at $\mathrm{\Omega }=\mathrm{\Delta }/\hslash$, with $\mathrm{\Delta }$ being the band gap of black phosphorene. Unlike the longitudinal optical conductivity, the optical Hall conductivity sharply increases when $\hslash \mathrm{\Omega }$ goes beyond one-half of the band gap $\mathrm{\Delta }/2$. We also show that the Chern number changes from trivial to nontrivial upon increasing frequency $\mathrm{\Omega }$ beyond $\hslash \mathrm{\Omega }=\mathrm{\Delta }/2$.

中文翻译：

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黑色磷光体的光诱导拓扑相变和光导率

我们从理论上研究了中等强度的激光诱导的黑色phosphor的光诱导拓扑相变，可以满足保留样品质量的实验现实要求。通过根据伪旋转推导有效的Floquet哈密顿量$\mathrm{小号}=\mathrm{1个}/2$ 自由度，我们计算出随激光频率变化的系统的Chern数和光导率 $\mathrm{\Omega }$。正如人们从光子辅助传输中可以预期的那样，纵向光导率的阈值频率为$\mathrm{\Omega }=\mathrm{\Delta }/\hslash$，带有 $\mathrm{\Delta }$是黑色磷的带隙。与纵向光导率不同，霍尔光导率在$\hslash \mathrm{\Omega }$ 超出了带隙的一半 $\mathrm{\Delta }/2$。我们还表明，随着频率的增加，切恩数从平凡变为平凡$\mathrm{\Omega }$ 超越 $\hslash \mathrm{\Omega }=\mathrm{\Delta }/2$。