We study femtosecond spin transport in a Gd|Pt stack induced by a laser pulse. Remarkably, the dynamics of the spin current from Gd to Pt suggests that its dominant driving force is the ultrafast spin Seebeck effect. As the contribution of a transient spin voltage in the metal Gd is minor, Gd acts akin a magnetic insulator here. This view is supported by time- and spin-resolved photoemission, which indicates that a buildup of spin voltage is suppressed by exchange scattering, leading to similar amplitudes and relaxation rates of hot majority- and minority-spin electron populations.
@article{arxiv.2503.22483,
title = {Magnon-mediated terahertz spin transport in metallic Gd|Pt stacks},
author = {Oliver Gueckstock and Tim Amrhein and Beatrice Andres and Pilar Jiménez-Cavero and Cornelius Gahl and Tom S. Seifert and Reza Rouzegar and Ilie Radu and Irene Lucas and Marko Wietstruk and Luis Morellón and Martin Weinelt and Tobias Kampfrath and Nele Thielemann-Kühn},
journal= {arXiv preprint arXiv:2503.22483},
year = {2025}
}