AI 中文总结
该研究利用线偏振光的Floquet驱动调控d波交替磁体的拓扑相与磁光响应，实现陈数切换与自旋分辨带反转，可用于非接触式光学探测。
AI 中文摘要
我们研究线偏振光驱动的Floquet调控如何控制二维d波交替磁体的拓扑性质与磁光响应。在无偏振光场且自旋守恒的情况下，该系统在两个自旋通道中存在自旋陈数（量子自旋霍尔效应的类似物）符号相反的自旋陈相。辐照的光场会破坏自旋通道间的C₄z𝒯晶体反幺正对称性，这种对称性破缺源于与偏振相关的Peierls相位，其会沿两个轴对跳跃进行各向异性重整化。由此产生的自旋选择性能隙关闭会形成中间陈绝缘相，其陈数C=±1。驱动振幅A₀决定了反转阈值，而将偏振旋转π/2会交换自旋通道并反转陈数。我们利用久保公式计算了频率相关的纵向与霍尔电导率，并推导了自由 standing导电片对应的法拉第与克尔旋转。纵向响应跟踪Floquet重整化的带间阈值，而光霍尔响应与磁光旋转的符号可区分两种相反的贝利曲率手性。仅在狭窄的共振窗口内会出现显著的克尔角，需结合反射强度与克尔椭偏率进行解读。这些结果表明，线偏振光是一种用于自旋分辨带反转、陈数切换及d波交替磁体非接触式光学探测的对称性选择性调控手段。
英文摘要
We study how Floquet driving with linearly polarized light controls the topology and magneto-optical response of a two-dimensional (2D) $d$-wave altermagnet. In the absence of linearly polarized optical field and under spin conservation, we find that the system hosts a spin-Chern (a quantum-spin-Hall analog) phase with Chern numbers of opposite sign in the two spin sectors. The irradiated optical field breaks the $C_{4z}\mathcal{T}$ crystalline antiunitary symmetry between the spin sectors. Symmetry breaking originates from polarization-dependent Peierls phases, which renormalize hopping anisotropically along the two axes. The resulting spin-selective gap closures produce intermediate Chern-insulating phases with $C=\pm1$. The drive amplitude $A_0$ determines the inversion thresholds, while rotating the polarization by $π/2$ swaps the spin sectors and reverses the Chern number. Using the Kubo formalism, we compute the frequency-dependent longitudinal and Hall conductivities and derive the corresponding Faraday and Kerr rotations for a free-standing conducting sheet. The longitudinal response tracks the Floquet-renormalized interband thresholds, whereas the optical Hall response, together with the sign of the magneto-optical rotations, distinguishes the two opposite Berry-curvature chiralities. Sizable Kerr angles occur only within narrow resonant windows and should be interpreted together with the reflected intensity and Kerr ellipticity. These results identify linearly polarized light as a symmetry-selective handle for spin-resolved band inversion, Chern-number switching, and contact-free optical detection in $d$-wave altermagnets.
