SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 46: Ultrafast Magnetization Effects II
MA 46.7: Vortrag
Freitag, 31. März 2023, 11:00–11:15, HSZ 02
Signature of spatial gradients in ultrafast demagnetization observed with angle-resolved complex magneto-optical Kerr-effect (CMOKE) — •Sanjay Ashok1, Jonas Hoefer1, Martin Stiehl1, Martin Aeschlimann1, Hans Christian Schneider1, Bärbel Rethfeld1, and Benjamin Stadtmüller1, 2 — 1Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Germany — 2Institute of Physics, Johannes Gutenberg-University Mainz, Germany
Understanding the laser-induced ultrafast magnetization dynamics of thick metallic films is even in simple materials still challenging due to different transport mechanisms contributing to the magnetization dynamics. While heat- and particle diffusion are slow processes, ballistic and superdiffusive transport lead to an ultrafast equilibration of spatial inhomogeneities. However, quantifying experimentally their impact on ultrafast demagnetization of bulk material is difficult, since surface-sensitive experimental techniques integrate the response of the material over a certain depth.
Our theoretical calculations reveal that the Kerr-rotation dynamics is nearly insensitive to gradients in magnetization. In contrast, we find a strong influence for the angle-resolved ellipticity dynamics. These findings are confirmed by CMOKE experiments on Nickel films of varying thicknesses. The probe-angle resolved CMOKE technique thus provides a method to study the presence of transient gradients in magnetization at ultrafast timescales.