We find unusually large cross-polarized (and antisymmetric) Raman signature of ${\mathrm{A}}_{\mathrm{g}}$ phonon mode in ${\mathrm{CrI}}_3$, in agreement with experiments. The signal is present only when the following three effects are considered in concert: ferromagnetism on Cr atoms, spin-orbit interaction, and resonant effects. Somewhat surprisingly, we find that the relevant spin-orbit interaction potential originates from iodine atoms, despite magnetism being mostly on chromium atoms. We analyze the Raman signature as a function of magnetic order, the direction of the magnetic moment, energy, and polarization of light used for Raman scattering, as well as carrier lifetime. In addition to a strong cross-polarized Raman signal, we also find unusually strong phonon modulated magneto-optical Kerr effect (MOKE) in ${\mathrm{CrI}}_3$.

中文翻译：

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CrI3中的大交叉极化拉曼信号：第一性原理研究

我们发现异常大的交叉极化（和反对称）拉曼信号 ${\mathrm{一种}}_{\mathrm{G}}$ 声子模式 ${铬}_3$，与实验一致。只有同时考虑以下三个效应时，才会出现信号：Cr原子上的铁磁性，自旋轨道相互作用和共振效应。出乎意料的是，尽管磁性主要集中在铬原子上，但我们发现相关的自旋轨道相互作用势源自碘原子。我们分析了拉曼信号随磁阶，磁矩方向，能量和用于拉曼散射的光的偏振以及载流子寿命的函数。除了强大的交叉极化拉曼信号外，我们还发现在光子晶体中有异常强的声子调制磁光克尔效应（MOKE）。${铬}_3$。