Spin-current-mediated rapid magnon localisation and coalescence after ultrafast optical pumping of ferrimagnetic alloys

Iacocca, E.; Liu, T. M.; Reid, A. H.; Fu, Z.; Ruta, S.; Granitzka, P. W.; Jal, E.; Bonetti, S.; Gray, A. X.; Graves, C. E.; Kukreja, R.; Chen, Z.; Higley, D. J.; Chase, T.; Le Guyader, L.; Hirsch, K.; Ohldag, H.; Schlotter, W. F.; Dakovski, G. L.; Coslovich, G.; Hoffmann, M. C.; Carron, S.; Tsukamoto, A.; Kirilyuk, A.; Kimel, A. V.; Rasing, Th; Stöhr, J.; Evans, R. F.L.; Ostler, T.; Chantrell, R. W.; Hoefer, M. A.; Silva, T. J.; Dürr, H. A.

Abstract

Sub-picosecond magnetisation manipulation via femtosecond optical pumping has attracted wide attention ever since its original discovery in 1996. However, the spatial evolution of the magnetisation is not yet well understood, in part due to the difficulty in experimentally probing such rapid dynamics. Here, we find evidence of a universal rapid magnetic order recovery in ferrimagnets with perpendicular magnetic anisotropy via nonlinear magnon processes. We identify magnon localisation and coalescence processes, whereby localised magnetic textures nucleate and subsequently interact and grow in accordance with a power law formalism. A hydrodynamic representation of the numerical simulations indicates that the appearance of noncollinear magnetisation via optical pumping establishes exchange-mediated spin currents with an equivalent 100% spin polarised charge current density of 10 7 A cm −2 . Such large spin currents precipitate rapid recovery of magnetic order after optical pumping. The magnon processes discussed here provide new insights for the stabilization of desired meta-stable states.

Citation

Iacocca, E., Liu, T. M., Reid, A. H., Fu, Z., Ruta, S., Granitzka, P. W., …Dürr, H. A. (2019). Spin-current-mediated rapid magnon localisation and coalescence after ultrafast optical pumping of ferrimagnetic alloys. Nature communications, 10(1), Article 1756. https://doi.org/10.1038/s41467-019-09577-0

• Journal Article Type: Article
• Acceptance Date: Mar 13, 2019
• Online Publication Date: Apr 15, 2019
• Publication Date: Dec 1, 2019
• Deposit Date: Jun 16, 2022
• Publicly Available Date: Jun 20, 2022
• Journal: Nature Communications
• Electronic ISSN: 2041-1723
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 1
• Article Number: 1756
• DOI: https://doi.org/10.1038/s41467-019-09577-0
• Keywords: Magnetic properties and materials; Phase transitions and critical phenomena
• Public URL: https://hull-repository.worktribe.com/output/4015067