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MA: Fachverband Magnetismus
MA 21: Ultrafast Magnetization II
MA 21.12: Vortrag
Dienstag, 17. März 2020, 12:30–12:45, HSZ 101
Thermally induced magnetic switching in GdFeCo using picosecond laser pulses - experiment vs theory — Florian Jakobs1, Thomas Ostler2, Jon Gorchon3, and •Unai Atxitia1 — 1Fachbereich Physik, Freie Universität Berlin Germany — 2Département de Physique, Universitè de Liege — 3Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, USA
There are still many open questions about the driving mechanisms behind ultrafast magnetic switching in GdFeCo alloys by a single femtosecond (fs) optical pulse. Phenomenological models suggest a fs-scale exchange relaxation between the sublattices, which would limit the stimuli time a fs-scale. However the recent observations of single-pulse switching with either optical, or electrical stimuli of up to ten picosecond, have questioned this previous understanding. In this work, we aim to bridge this gap of knowledge. To that end, we have studied single-pulse optical switching, both experimentally and theoretically, for a wide range of system parameters, such as composition, laser power and pulse duration. For the first time we have found excellent quantitative agreement between our atomistic spin model and experiments across a broad range of compositions and laser durations ranging from fs to ps. Furthermore we explore numerically the impact of various switching parameters, that are typically unaccessible to experiments. Such as Gd-concentration, element-specific relaxation parameter, pulse duration and fluence. In agreement with previous experiments, we find the conditions for switching up to pulse durations close to ten ps.