AI 中文总结
该研究通过光学光谱和第一性原理计算，在交替磁绝缘体La$_2$O$_3$Mn$_2$Se$_2$中观察到由暗激子与磁子耦合产生的镜像边带，确立了激子-磁子光谱学作为识别交替磁体的新方法。
AI 中文摘要
交替磁体（AMs）的非相对论自旋劈裂能够实现新奇的态、自旋电子学和磁光器件，尽管其光学特征仍然难以捉摸。在此，我们报道了激子-磁子发射与吸收：来自自旋禁戒暗激子的光学边带，这是交替磁对称性的直接结果。结合光学光谱和第一性原理计算揭示，La$_2$O$_3$Mn$_2$Se$_2$是一种交替磁绝缘体，拥有一个强束缚的自旋禁戒暗激子和一个更高能量的亮激子。光致发光（PL）和吸收光谱显示出镜像对称的边带，在发射中发生斯托克斯位移，在吸收中发生反斯托克斯位移，并围绕暗激子对称，其能量位移和光谱形状与通过非弹性中子散射独立测量的磁子能量尺度和态密度相匹配。PL强度追踪完整的等时自旋-自旋关联函数，结合了静态和动态贡献，并排除了其他过程。这直接将PL与磁性联系起来，为磁光器件提供了潜力。这些结果确立了激子-磁子光谱学作为光学识别和利用AMs的新途径。
英文摘要
Altermagnets' (AMs) non-relativistic spin splitting enables novel states, spintronic and magneto-optical devices, though their optical signatures remain elusive. Here, we report exciton-magnon emission and absorption: optical sidebands from a spin-forbidden dark exciton, a direct consequence of altermagnetic symmetry. Combined optical spectroscopy and first-principles calculations reveal that La$_2$O$_3$Mn$_2$Se$_2$ is an altermagnetic insulator, hosting a strongly bound, spin-forbidden dark exciton and a higher-energy bright exciton. Photoluminescence (PL) and absorption reveal mirror-image sidebands, Stokes-shifted in emission and anti-Stokes-shifted in absorption, symmetric about the dark exciton, whose energy shifts and spectral shapes match the magnon energy scale and density of states measured independently by inelastic neutron scattering. The PL intensity tracks the full equal-time spin-spin correlator, combining static and dynamical contributions, and rules out alternative processes. This directly couples PL to magnetism, with potential for magneto-optical devices. These results establish exciton-magnon spectroscopy as a new route for optically identifying and exploiting AMs.
