Hierarchical quasiparticle dynamics in antiferromagnets revealed by time- and momentum-resolved X-ray scattering
Abstract
Energy flows among coupled subsystems are essential for ultrafast dynamics and high-speed technologies. In magnetic materials, spin fluctuations -- magnons -- mediate these flows in ultrafast magnetism. Yet momentum-resolved access to low-energy magnons governing the microscopic dynamics has been lacking. Using time-resolved resonant diffuse scattering alongside complementary time-resolved X-ray techniques and quantum-kinetic simulations, we unveil the hierarchical energy pathways among correlated systems in the photoexcited antiferromagnet CuO. Above-bandgap excitation triggers near-instantaneous spin disorder, generating non-thermal magnons throughout reciprocal space within femtoseconds. Real-time momentum-resolved tracking reveals picosecond magnon quasi-thermalization, followed by nanosecond recovery via momentum-selective magnon-phonon scattering. The quasiparticle dispersion mismatch creates recovery bottlenecks that control non-equilibrium lifetimes. This microscopic framework transcends phenomenological models and generalizes across materials, establishing design principles for ultrafast control of material properties.
Keywords
Cite
@article{arxiv.2602.13113,
title = {Hierarchical quasiparticle dynamics in antiferromagnets revealed by time- and momentum-resolved X-ray scattering},
author = {Arnau Romaguera and Elizabeth Skoropata and Yun Yen and Biaolong Liu and Abhishek Nag and Shih-Wen Huang and Ludmila Leroy and Katja Sophia Moos and Gian Parusa and Serhane Zerdane and Ritwika Mandal and Celine Mariette and Matteo Levantino and Eugenio Paris and Luc Patthey and Ekaterina Pomjakushina and Urs Staub and Monica Ciomaga Hatnean and Michael Schueler and Elia Razzoli and Hiroki Ueda},
journal= {arXiv preprint arXiv:2602.13113},
year = {2026}
}
Comments
57 pages, 21 figures