We report on the observation of the coherent optical phonon in a hexagonal YMnO3 epitaxial film using a reflection-type pump-probe technique at various temperatures, excitation powers, and energies. We detected an oscillatory structure with a frequency of ∼5.1 THz, which is assigned to the coherent optical phonon with A1 symmetry, in a time-domain signal. It was found that the coherent optical phonon can be observed at temperatures from 10 K to room temperature, while the oscillation amplitude markedly decreases with an increase in temperature around ∼70 K corresponding to the Neel temperature. The temperature dependence of the oscillation amplitude indicates that the coherent optical phonon is sensitive to the spin-lattice coupling connected with the antiferromagnetic transition.

中文翻译：

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与六方 YMnO3 外延膜中的反铁磁跃迁相关的相干光学声子的超快动力学

我们报告了使用反射型泵浦探针技术在不同温度、激发功率和能量下观察六方 YMnO3 外延膜中的相干光学声子。我们在时域信号中检测到频率约为 5.1 THz 的振荡结构，该结构分配给具有 A1 对称性的相干光声子。发现在 10 K 到室温的温度下可以观察到相干光声子，而振荡幅度随着温度的升高而显着减小，大约 70 K 对应于尼尔温度。振荡幅度的温度依赖性表明相干光声子对与反铁磁转变相关的自旋晶格耦合敏感。