Ultrafast spin transport as key to femtosecond demagnetization
- Irradiating a ferromagnet with a femtosecond laser pulse is known to induce an ultrafast demagnetization within a few hundred femtoseconds. Here we demonstrate that direct laser irradiation is in fact not essential for ultrafast demagnetization, and that electron cascades caused by hot electron currents accomplish it very efficiently. We optically excite a Au/Ni layered structure in which the 30 nm Au capping layer absorbs the incident laser pump pulse and subsequently use the X-ray magnetic circular dichroism technique to probe the femtosecond demagnetization of the adjacent 15 nm Ni layer. A demagnetization effect corresponding to the scenario in which the laser directly excites the Ni film is observed, but with a slight temporal delay. We explain this unexpected observation by means of the demagnetizing effect of a superdiffusive current of non-equilibrium, non-spin-polarized electrons generated in the Au layer.
Author details: | Andrea EschenlohrGND, Marco BattiatoORCiD, R. Maldonado, N. Pontius, T. Kachel, K. Holldack, Rolf MitznerORCiDGND, Alexander FöhlischORCiDGND, P. M. Oppeneer, C. Stamm |
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DOI: | https://doi.org/10.1038/NMAT3546 |
ISSN: | 1476-1122 |
Title of parent work (English): | Nature materials |
Publisher: | Nature Publ. Group |
Place of publishing: | London |
Publication type: | Article |
Language: | English |
Year of first publication: | 2013 |
Publication year: | 2013 |
Release date: | 2017/03/26 |
Volume: | 12 |
Issue: | 4 |
Number of pages: | 5 |
First page: | 332 |
Last Page: | 336 |
Funding institution: | German Ministry of Education and Research BMBF [05K10PG2 FEMTOSPEX]; Swedish Research Council (VR); European Community [214810 FANTOMAS, 281043 FEMTOSPIN]; Swedish National Infrastructure for Computing (SNIC) |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
Peer review: | Referiert |