Exciton dynamics can be strongly affected by lattice vibrations through electron-phonon coupling. This is rarely explored in two-dimensional magnetic semiconductors. Focusing on bilayer CrI₃, we first show the presence of strong electron-phonon coupling through temperature-dependent photoluminescence and absorption spectroscopy. We then report the observation of periodic broad modes up to the 8th order in Raman spectra, attributed to the polaronic character of excitons. We establish that this polaronic character is dominated by the coupling between the charge-transfer exciton at 1.96 eV and a longitudinal optical phonon at 120.6 cm⁻¹. We further show that the emergence of long-range magnetic order enhances the electron-phonon coupling strength by ~50% and that the transition from layered antiferromagnetic to ferromagnetic order tunes the spectral intensity of the periodic broad modes, suggesting a strong coupling among the lattice, charge and spin in two-dimensional CrI₃. Our study opens opportunities for tailoring light-matter interactions in two-dimensional magnetic semiconductors.

激子动力学可以通过电子-声子耦合受到晶格振动的强烈影响。这在二维磁性半导体中很少被探索。关注双层 CrI ₃，我们首先通过温度相关的光致发光和吸收光谱显示强电子-声子耦合的存在。然后我们报告了在拉曼光谱中观察到高达 8 阶的周期性宽模式，这归因于激子的极化特性。我们确定这种极化子特性由 1.96 eV 处的电荷转移激子和 120.6 cm ^-1处的纵向光学声子之间的耦合决定. 我们进一步表明，长程磁序的出现将电子-声子耦合强度提高了约 50%，并且从分层反铁磁到铁磁序的转变调整了周期性宽模式的光谱强度，表明晶格之间存在强耦合，在二维 CrI _{3 中}充电和自旋。我们的研究为定制二维磁性半导体中的光-物质相互作用开辟了机会。