Spin waves excited by hard x-ray transient gratings
Abstract
Recent progress in ultrafast x-ray sources helped establish x-rays as an important tool for probing lattice and magnetic dynamics initiated by femtosecond optical pulses. Here, we explore the potential of ultrashort hard x-ray pulses for driving magnetic dynamics. We use a transient grating technique in which a spatially periodic x-ray excitation pattern gives rise to material excitations at a well-defined wave vector, whose dynamics are monitored via diffraction of an optical probe pulse. The excitation of a ferrimagnetic gadolinium bismuth iron garnet film placed in an external tilted magnetic field by x-rays at the Gd L3 edge results in both magnetic and non-magnetic transient gratings whose contributions to the diffracted signal are separated by polarization analysis. We observe the magnetization precession at both longitudinal acoustic and spin wave frequencies. An analysis with the Landau-Lifshitz-Gilbert equation indicates that the magnetization precession is driven by strain resulting from thermal expansion induced by absorbed x-rays. The results establish x-ray transient gratings as a tool for driving coherent phonons and magnons, with the potential of accessing wave vectors across the entire Brillouin zone.
Cite
@article{arxiv.2601.05941,
title = {Spin waves excited by hard x-ray transient gratings},
author = {Peter R. Miedaner and Alexei A. Maznev and Mykola Biednov and Marwan Deb and Carles Serrat and Nadia Berndt and Pietro Carrara and Cristian Soncini and Marta Brioschi and Daniele Ronchetti and Andrei Benediktovitch and Danny Fainozzi and Nupur Khatu and Eugenio Ferrari and Joan Vila-Comamala and Peter Zalden and Wojciech Gawelda and Martin Knoll and Paul Frankenberger and Ludmila Leroy and Talgat Mamyrbayev and Grigory Smolentsev and Simon Gerber and Alessandro Gessini and Filippo Bencivenga and Riccardo Cucini and Giorgio Rossi and Riccardo Mincigrucci and Ettore Paltanin and Majed Chergui and Claudio Masciovecchio and Stefano Bonetti and Yohei Uemura and Xinchao Huang and Han Xu and Frederico Alves Lima and Fernando Ardana-Lamas and Anders Madsen and Renato Torre and Luis Bañares and Jakub Szlachetko and Wojciech Blachucki and Matias Bargheer and Thomas Feurer and Robin Y. Engel and Martin Beye and Christian David and Urs Staub and Andrea Cannizzo and Cristopher Milne and Keith A. Nelson and Cristian Svetina},
journal= {arXiv preprint arXiv:2601.05941},
year = {2026}
}