We use transient absorption spectroscopy with circularly polarized x-rays to detect laser-excited hole states below the Fermi level and compare their dynamics with that of unoccupied states above the Fermi level in ferromagnetic [Co/Pd] multilayers. While below the Fermi level an instantaneous and significantly stronger demagnetization is observed, above the Fermi level the demagnetization is delayed by 35+/-10 fs. This provides a direct visualization of how ultrafast demagnetization proceeds via initial spin-flip scattering of laser-excited holes to the subsequent formation of spin waves.
@article{arxiv.2110.15615,
title = {State-resolved ultrafast charge and spin dynamics in [Co/Pd] multilayers},
author = {Loïc Le Guyader and Daniel J. Higley and Matteo Pancaldi and Tianmin Liu and Zhao Chen and Tyler Chase and Patrick W. Granitzka and Giacomo Coslovich and Alberto A. Lutman and Georgi L. Dakovski and William F. Schlotter and Padraic Shafer and Elke Arenholz and Olav Hellwig and Mark L. M. Lalieu and Bert Koopmans and Alexander H. Reid and Stefano Bonetti and Joachim Stöhr and Hermann A. Dürr},
journal= {arXiv preprint arXiv:2110.15615},
year = {2022}
}
Comments
10 pages, 4 figures. The following article has been submitted to Applied Physics Letters. After it is published, it will be found at https://publishing.aip.org/resources/librarians/products/journals/