The advent of free electron lasers has opened the opportunity to explore interactions between extreme ultraviolet (EUV) photons and collective excitations in solids. While EUV transient grating spectroscopy, a noncollinear four-wave mixing technique, has already been applied to probe coherent phonons, the potential of EUV radiation for studying nanoscale spin waves has not been harnessed. Here we report EUV transient grating experiments with coherent magnons in Fe/Gd ferrimagnetic multilayers. Magnons with tens of nanometers wavelengths are excited by a pair of femtosecond EUV pulses and detected via diffraction of a probe pulse tuned to an absorption edge of Gd. The results unlock the potential of nonlinear EUV spectroscopy for studying magnons and provide a tool for exploring spin waves in a wave vector range not accessible by established inelastic scattering techniques.

中文翻译：

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通过极紫外瞬态光栅激发和探测相干纳米级自旋波


自由电子激光器的出现为探索固体中的极紫外 （EUV） 光子和集体激发之间的相互作用提供了机会。虽然 EUV 瞬态光栅光谱（一种非共线四波混合技术）已经应用于探测相干声子，但 EUV 辐射在研究纳米级自旋波方面的潜力尚未得到利用。在这里，我们报告了在 Fe/Gd 亚铁磁性多层层中使用相干磁振子的 EUV 瞬态光栅实验。具有数十纳米波长的磁振子由一对飞秒 EUV 脉冲激发，并通过调谐到 Gd 吸收边缘的探针脉冲的衍射来检测。这些结果释放了非线性 EUV 光谱学在研究磁振子方面的潜力，并为在已建立的非弹性散射技术无法获得的波矢范围内探索自旋波提供了一种工具。