Temperature- and fluence-dependent carrier dynamics of the magnetic kagome metal Fe₃Sn₂ were studied using the ultrafast optical pump-probe technique. Two carrier relaxation processes and a laser-induced coherent optical phonon were observed. We ascribe the shorter relaxation (~1 ps) to hot electrons transferring their energy to the crystal lattice via electron–phonon scattering. The second relaxation (~30 ps), on the other hand, cannot be explained as a conventional process, and we attributed it to the unconventional (localized) carriers in the material. The observed coherent oscillation is assigned to be a totally symmetric A_1g optical phonon dominated by Sn displacements out of the kagome planes and possesses a prominently large amplitude, on the order of 10⁻³, comparable to the maximum of the reflectivity change (ΔR/R). This amplitude is similar to what has been observed for coherent phonons in charge-density-wave (CDW) systems, although no signs of such instability were hitherto reported in Fe₃Sn₂. Our results suggest an unexpected connection between Fe₃Sn₂ and kagome metals with CDW instabilities and a strong interplay between phonon and electron dynamics in this compound.

使用超快光泵浦探针技术研究了磁性 kagome 金属 Fe ₃ Sn ₂的温度和注量依赖性载流子动力学。观察到两个载流子弛豫过程和激光诱导相干光学声子。我们将较短的弛豫时间（~1 ps）归因于热电子通过电子声子散射将其能量转移到晶格。另一方面，第二次弛豫（~30 ps）不能解释为传统过程，我们将其归因于材料中的非常规（局部）载流子。观察到的相干振荡被指定为完全对称的A _{1 g}光学声子，主要由戈薇平面外的 Sn 位移主导，并且具有 10 ^-3量级的显着大幅度，与反射率变化的最大值（ΔR /R）。该振幅类似于在电荷密度波（CDW）系统中观察到的相干声子的振幅，尽管迄今为止在Fe ₃ Sn ₂中没有报道这种不稳定性的迹象。我们的结果表明 Fe ₃ Sn ₂和 kagome 金属之间存在意想不到的联系，具有 CDW 不稳定性以及该化合物中声子和电子动力学之间的强烈相互作用。