Abstract Thermal interaction in an electron-phonon-magnon system in a ferromagnetic Ni film is investigated using a time-resolved pump-probe technique with thermoreflectance and magneto-optical Kerr effect. A nanoscale Au/Ni bilayer is used to induce thermal excitation of Ni in two ways: direct heating of Ni and indirect heating of Ni via Au. By comparing experiments and thermal modeling, we obtain the coupling parameters for electron-phonon, electron-magnon, and phonon-magnon pairs: 8.55 × 1017, 1.0–1.3 × 1017, and 0.8–1.1 × 1017 W m−3 K−1, respectively. In particular, we find that the phonon-magnon coupling parameter plays a significant role as a fast heat dissipation channel from magnon to phonon during the initial few picoseconds. In addition, both direct and indirect heating can be explained by similar coupling parameters with a variation less then 30%. Consequently, we conclude that the heat exchange between electron, phonon, and magnon is the dominant mechanism for the ultrafast demagnetization.

中文翻译：

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镍的电子、声子和磁振子之间的热耦合参数

摘要 使用具有热反射和磁光克尔效应的时间分辨泵浦探针技术研究了铁磁 Ni 膜中电子-声子-磁振子系统中的热相互作用。纳米级 Au/Ni 双层用于以两种方式诱导 Ni 的热激发：直接加热 Ni 和通过 Au 间接加热 Ni。通过比较实验和热建模，我们获得了电子-声子、电子-磁子和声子-磁子对的耦合参数：8.55 × 1017、1.0–1.3 × 1017 和 0.8–1.1 × 1017 W m−3 K−1 ， 分别。特别是，我们发现声子-磁振子耦合参数在最初的几皮秒内作为从磁振子到声子的快速散热通道起着重要作用。此外，直接和间接加热都可以用类似的耦合参数来解释，变化小于 30%。因此，我们得出结论，电子、声子和磁振子之间的热交换是超快退磁的主要机制。