发表机构
IIT Madras; Indian Institute of Science（印度理工学院马德拉斯分校; 印度科学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过考虑长程偶极-偶极相互作用，准确计算了交替磁体$\alpha$-MnTe的声子带结构，揭示了隐藏拉曼模式，解释了实验与理论拉曼光谱的差异，并阐明了各争议峰的起源。
AI 中文摘要
在本研究中，我们探讨了交替磁体$\alpha$-MnTe的实验与理论观测拉曼光谱之间差异这一看似悬而未决的问题。我们确定，考虑长程（LR）偶极-偶极相互作用对于准确估算声子带结构，从而捕捉每个实验观测到的拉曼特征至关重要。LR修正给高频光学模式及其群论表示带来了实质性变化。具体而言，对于备受争议的约175 cm$^{-1}$拉曼峰，除了拉曼静默的B$_{1u}$模式外，LR修正还引入了拉曼活性的纵向光学A$^{\prime}$和A$_1$模式，以及横向光学A$_1$模式。总体而言，计算得到的拉曼光谱表明，在纯净系统中这些模式的强度较弱，而某些特定畸变可以增强其强度。实验观测到的约140 cm$^{-1}$拉曼峰被确定为源于高阶拉曼过程，由区域离中心贡献产生，而另一个有争议的120 cm$^{-1}$峰则同时具有区域中心和区域离中心的贡献。
英文摘要
In this study, we address the seemingly open question of disparity between the experimentally and theoretically observed Raman spectra for the altermagnetic $α$-MnTe. We establish that the consideration of long range (LR) dipole-dipole interaction is crucial to accurately estimate the phonon band structure and thereby capturing each of the experimentally observed Raman signatures. The LR correction brings about substantial changes to the high-frequency optical modes and their group-theoretical representations. Specifically, for the highly debated Raman peak around 175 cm$^{-1}$, alongside the Raman silent B$_{1u}$ mode, the LR corrections introduce Raman-active longitudinal optical A$^{\prime}$ and A$_1$, and transverse optical A$_1$ modes. Overall, the calculated Raman spectra suggest that the intensity of these modes is weak in the pristine system, while certain prescribed distortions can increase their intensity. The Raman peak around 140 cm$^{-1}$, as observed experimentally, is identified to be emerging from a higher-order Raman process due to zone off-center contributions, while the other debated 120 cm$^{-1}$ peak has both the zone center and off-center contributions.
Comments7 pages, 5 figures
