Spin dynamics of TmFeO, mainly induced by two different mechanisms, were investigated by time-resolved multicolor pump-probe spectroscopy using femtosecond laser pulses. The spin dynamics, caused either by spin-reorientation phase transition or optical polarization-dependent effect, were distinguished by investigating their dependencies on external magnetic field and optical polarization. Spectral-dependent magneto-optic studies of the spin phase transition-induced spin dynamics revealed that laser-induced nonthermal exchange interaction between the electron states of iron (Fe) and thulium (Tm) ions is crucial for subsequent spin dynamics. This exchange interaction is influenced by the population change of the 4f electron states of Tm ions, making the spin wave generation highly dependent on crystal temperature. However, spectroscopic studies of the polarization-dependent spin dynamics show that they are only related to the 3d electrons of Fe ions, therefore, the spin dynamics appear to be a universal effect over a wide temperature range. Our observation can be further applied to study extended orthoferrite systems with other rare earth atoms.

中文翻译：

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时间分辨多色光泵浦探针光谱研究 TmFeO3 自旋激发的微观起源

TmFeO 的自旋动力学主要由两种不同的机制引起，通过使用飞秒激光脉冲的时间分辨多色泵浦探针光谱进行了研究。通过研究自旋重定向相变或光学偏振相关效应引起的自旋动力学对外部磁场和光学偏振的依赖性，可以区分它们。自旋相变引起的自旋动力学的光谱相关磁光研究表明，激光引起的铁 (Fe) 和铥 (Tm) 离子电子态之间的非热交换相互作用对于后续的自旋动力学至关重要。这种交换相互作用受到Tm离子4f电子态布居变化的影响，使得自旋波的产生高度依赖于晶体温度。然而，对偏振相关自旋动力学的光谱研究表明，它们仅与 Fe 离子的 3d 电子有关，因此，自旋动力学似乎是在很宽的温度范围内的普遍效应。我们的观察可以进一步应用于研究与其他稀土原子的扩展正铁氧体系统。