We performed time-resolved x-ray resonant magnetic reflectivity measurements on a laser-excited ferromagnetic Fe thin film to simultaneously probe the transient structural and magnetic depth profiles with nanometer spatial and femtosecond temporal resolution. Our results show that during the first picoseconds after optical excitation, the magnetization of the Fe layer is strongly inhomogeneous, especially in the vicinity of the buried interface. By comparing our experimental results to predictions based on the microscopic three-temperature model and simulations of laser-induced spin-currents, we demonstrate that local and non-local angular momentum transfer phenomena take place simultaneously. After a few picoseconds, the magnetization relaxes back to equilibrium while the total thin film thickness starts oscillating periodically, with a maximum dilation of approximately 1.3% of the entire thin film thickness due to laser-induced stresses.
@article{arxiv.2603.11913,
title = {Depth-resolved magnetization dynamics in Fe thin films after ultrafast laser excitation},
author = {Valentin Chardonnet and Marcel Hennes and Romain Jarrier and Renaud Delaunay and Nicolas Jaouen and Marion Kuhlmann and Cyril Leveillé and Clemens von Korff Schmising and Daniel Schick and Kelvin Yao and Xuan Liu and Gheorghe S. Chiuzbăian and Jan Lüning and Boris Vodungbo and Emmanuelle Jal},
journal= {arXiv preprint arXiv:2603.11913},
year = {2026}
}