We have measured the hot-electron induced demagnetization of a [Co/Pt]2 multilayer in M(x nm)/Cu(100 nm)/[Co(0.6 nm)/Pt(1.1 nm)]2 samples depending on the nature of the capping layer M and its thickness x. We found out that a Pt layer is more efficient than [Co/Pt]X, Cu or MgO layers in converting IR photon pulses into hot-electron pulses at a given laser power. We also found out that the maximum relative demagnetization amplitude is reached for M(x) = Pt (7 nm). Our experimental results show qualitative agreement with numerical simulations based on the superdiffusive spin transport model. We concluded that the maximum relative demagnetization amplitude, which corresponds to the highest photon conversion into hot-electrons, is an interplay between the IR penetration depth and the hot-electron inelastic mean free path within the capping layer.
@article{arxiv.2006.07005,
title = {Tailoring femtosecond hot-electron pulses for ultrafast spin manipulation},
author = {Nicolas Bergeard and Michel Hehn and Karel Carva and Pavel Baláž and Stéphane Mangin and Gregory Malinowski},
journal= {arXiv preprint arXiv:2006.07005},
year = {2021}
}