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Ever brighter x-ray laser sources give rise to the possibility of using ultrafast hard x-rays to directly drive nanoscale lattice and magnetic dynamics. Recently, hard x-ray excitation of phonons was demonstrated using the x-ray transient grating (XTG) technique [1], but driving of magnetic dynamics in this regime has remained unexplored. In this work, we use XTG to excite magnetic precession in the insulating ferrimagnet gadolinium bismuth iron garnet (GdIG). Using Talbot imaging of a phase grating, x-ray photoionization occurs in a spatially periodic pattern. This results in the excitation of both bulk acoustic waves and a step-like periodic strain, which act as sources of torque on the spin system through inverse magnetostriction. Magnetization precession at the acoustic and spin wave frequencies were observed via diffraction of time-delayed optical pulse.[2] A micromagnetic model based on the Landau-Lifshitz-Gilbert equation corroborates that the spin waves were driven by x-ray generated strain. XTG is further established as a powerful technique to drive coherent nanoscale lattice and magnetic dynamics throughout the Brillouin zone.
[1] J. R. Rouxel et al., Hard x-ray transient grating spectroscopy on bismuth germinate, Nat. Photonics 15, 499 (2021).
[2] P. R. Miedaner et al., Spin Waves Excited by Hard X-Ray Transient Gratings, Phys. Rev. Lett. 136, 176701 (2026).
| Scientific Topics | Solid State Physics |
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