发表机构
Abrikosov Center for Theoretical Physics, Moscow Institute of Physics and Technology（莫斯科物理技术学院阿布里科索夫理论物理中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出宏观电动力学框架，分离铋取代铁石榴石磁光效应中磁偶极与电偶极贡献，发现红外波段二者交叉相等，并证明s偏振横向克尔效应完全由非对角磁导率驱动，可作为THz至MIR–NIR波段MD活性的稳健探针。
AI 中文摘要
本工作提出了一个全面的宏观电动力学框架，用于分离铋取代铁石榴石中磁光效应的磁偶极（MD）和电偶极（ED）贡献。通过严格纳入色散磁导率张量，证明了MD机制在太赫兹（THz）间隙中的主导地位。在中红外（MIR）到近红外（NIR）波段，揭示了一个基本的频谱交叉现象，其中MD和ED贡献的幅度恰好相等，从而否定了磁性贡献在红外频率下均匀消失的普遍假设。此外，研究表明界面相移独特地决定了这些竞争机制如何投影到可观测的旋转和椭偏率上，导致透射（法拉第）和反射（极向及纵向克尔）几何之间出现倒置的光谱层级。最值得注意的是，对于s偏振光，横向克尔效应被确立为完全由磁导率的非对角分量驱动。虽然在传统ED近似下严格为零，但s偏振横向克尔效应作为一种不受旋电贡献影响的MD活性探针，在THz和MIR–NIR波段表现稳健，其THz响应比p偏振对应物大两个数量级。
英文摘要
This work presents a comprehensive macroscopic electrodynamic framework isolating the magnetodipole (MD) and electrodipole (ED) contributions to the magneto-optical effects in bismuth-substituted iron garnet. By rigorously incorporating the dispersive magnetic permeability tensor, the dominance of the MD mechanism in the terahertz (THz) gap is demonstrated. In the mid-infrared (MIR) to near-infrared (NIR) domain, a fundamental spectral crossover is revealed where the magnitudes of the MD and ED contributions exactly equalize, invalidating the widespread assumption that magnetic contributions vanish uniformly at infrared frequencies. Furthermore, it is shown that interfacial phase shifts uniquely dictate how these competing mechanisms project onto observable rotation and ellipticity, yielding an inverted spectral hierarchy between transmission (Faraday) and reflection (polar and longitudinal Kerr) geometries. Most notably, the transverse Kerr effect for s-polarized light is established to be exclusively driven by the off-diagonal magnetic permeability. While strictly zero under the conventional ED approximation, the s-polarized transverse Kerr effect emerges as a robust, free of the gyroelectric contribution probe of MD activity in the THz and MIR--NIR regimes, yielding a THz response two orders of magnitude larger than its p-polarized counterpart.
