Tuning ultrafast demagnetization with ultrashort spin polarized currents in multi-sublattice ferrimagnetsShow others and affiliations
2025 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 16, no 1, article id 3097Article in journal (Refereed) Published
Abstract [en]
Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. Several microscopic mechanisms have been proposed to explain these observations, including the transport of ultrashort spin-polarized hot-electrons (SPHE). However, currently such ultrafast spin currents are only poorly characterized due to the measurement requirements for element and time resolution. Here, using time- and element-resolved X-ray magnetic circular dichroism alongside atomistic spin-dynamics simulations, we study the ultrafast transfer of the angular momentum from spin-polarized currents. We show that using a Co/Pt multilayer as a polarizer in a spin-valve structure, the SPHE drives the demagnetization of the two sub-lattices of the Fe74Gd26 film. This behaviour can be explained with two physical mechanisms; spin transfer torque and thermal fluctuations induced by the SPHE. We provide a quantitative description of the heat transfer of the ultrashort SPHE pulse to the Fe74Gd26 films, as well as the effect of spin-polarization of the SPHE current density responsible for the observed magnetization dynamics. Our work finally characterizes the spin-polarization of the SPHEs revealing unexpected opposite spin polarization to the Co magnetization.
Place, publisher, year, edition, pages
Springer Nature, 2025. Vol. 16, no 1, article id 3097
Keywords [en]
angular momentum, demagnetization, heat transfer, lattice dynamics, polarization, torque
National Category
Condensed Matter Physics
Research subject
Physics and Mathematics
Identifiers
URN: urn:nbn:se:his:diva-25004DOI: 10.1038/s41467-025-58411-3ISI: 001456731600007PubMedID: 40164666Scopus ID: 2-s2.0-105001649899OAI: oai:DiVA.org:his-25004DiVA, id: diva2:1951171
Funder
EU, Horizon 2020, Marie Skłodowska-Curie grant agreement number 847471Olle Engkvists stiftelseSwedish Research CouncilEU, European Research CouncilKnut and Alice Wallenberg FoundationSwedish Research Council, 2018-05973
Note
CC BY-NC-ND 4.0
© The Author(s) 2025
Correspondence Address: C. Boeglin; Institut de Physique et de Chimie des Matériaux de Strasbourg, UMR7504, CNRS et Université de Strasbourg, Strasbourg, France; email: christine.boeglin@ipcms.unistra.fr
We are indebted to R. Mitzner and M. Mawass for help and support during the femtoslicing experiments. This work was supported by funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 847471, by the “Agence Nationale de la Recherche” in France via the project ANR−20-CE42-0012-01 (MEDYNA), ANR−21-CE42-0004-01 (EXPERTISE) and by the German Ministry of Education and Research BMBF Grant 05K10PG2 (FEMTOSPEX). This work was financially supported by Olle Engkvist Foundation. Support from STandUP and eSSENCE is also acknowledged. O.E. also acknowledge support from the Swedish Research Council, the European Research Council (ERC) as well as the Wallenberg Initiative Materials Science for Sustainability (WISE) funded by the Knut and Alice Wallenberg Foundation (KAW), the Swedish Research Council and the Knut and Alice Wallenberg Foundation (KAW). Computations were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC/NAISS) at NSC, partially funded by the Swedish Research Council through grant agreement no. 2018-05973. R.A. acknowledge financial support by the German Federal Ministry of Education and Research BMFG project number 05K19WO61. This work was supported by the ANR through the France 2030 government grants PEPR SPIN – SPINMAT ANR-22-EXSP- 0007
2025-04-102025-04-102025-11-18Bibliographically approved