Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 2: Ultrafast Magnetization I

MA 2.3: Talk

Monday, March 16, 2020, 10:00–10:15, HSZ 101

Ultrafast magnetization dynamics of ferromagnets on thin metal films — •Jonas Hoefer, Martin Stiehl, Christopher Seibel, Laura Scheuer, Simon Häuser, Sebastian T. Weber, Sanjay Ashok, Philipp Pirro, Burkhard Hillebrands, Benjamin Stadtmüller, Bärbel Rethfeld, and Martin Aeschlimann — Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany

After the first observation of the ultrafast demagnetization process of ferromagnetic thin films, huge efforts were devoted to reveal the microscopic mechanism governing the ultrafast optically induced loss of magnetic order in ferromagnetic materials. It was soon realized that spin transport from a ferromagnetic into a non-magnetic metal can severely increase the speed of demagnetization of magnetic materials. So far, experimental studies focused on bulk-like non-magnetic thin films acting as a sink for the injected spins. In our study, we particular address the correlation between the demagnetization dynamics of a thin magnetic film and the thickness of a non-magnetic gold film underneath. Using time-resolved all-optical pump-probe MOKE experiments, we investigated the demagnetization time of a permalloy/gold bilayer systems for various Au film thicknesses. We find significantly longer demagnetization times for thin Au thicknesses compared to bulk-like Au films. These results will be discussed via theoretical model simulations describing the non-equilibrium dynamics of the optically excited spin carriers and their coupling through the interface.