Regensburg 2013 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 22: Poster II
DF 22.50: Poster
Freitag, 15. März 2013, 10:30–13:30, Poster D
Influence of hot electrons on the ultrafast quench of magnetization in Ni and FePt — •Martin Lüttich1, Jakob Walowski1, Andreas Mann1, Johannes Mendil1, Markus Münzenberg1, Unai Atxitia2, and Oksana Chubykalo-Fesenko2 — 1I. Physikalisches Institut Georg-August-Universität Göttingen, Göttingen, Germany — 2Instituto de Ciencia de Materiales de Madrid, Madrid, Spain
Since the first investigation of ultrafast magnetization dynamics in 1996, the question on driving mechanism(s) is still not resolved entirely. According to the predicted superdiffusive spin transport, we investigate the influence of hot electrons on the relative demagnetization.
Magnetization dynamics of an in-plane magnetized Ni film and an out-of-plane magnetized FePt film is measured using the all-optical pump-probe technique for various pump pulse fluences. To clarify the influence of hot electrons on the relative demagnetization, experiments with temporarily stretched pump pulses from 50 fs up to 2.5 ps are performed. These results are compared to simulations based on the Landau-Lifshitz-Bloch equation, which is based on the thermal model, and featured by the consideration of two spin temperature dependent relaxation times τ|| and τ⊥. The electron temperature needed as input for the simulations is obtained from independent experiments on reflectivity dynamics. Compared to experiments, using ultrashort 80 fs pump pulses containing same energy per pulse, a lower maximum electron temperature is reached, but it is maintained for a longer time with the longer pump pulses.