Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 26: Ultrafast Magnetization Effects I
MA 26.10: Talk
Wednesday, March 19, 2025, 17:30–17:45, H16
Differentiating mechanisms that drive ultrafast magnetization precession — •Fried-Conrad Weber1,2, Maximilian Mattern3, Jasmin Jarecki3, Marwan Deb1, Dieter Engel3, Daniel Schick3, Alexander von Reppert1 und Matias Bargheer1,2 — 1Universität Potsdam — 2Helmholtz-Zentrum für Materialien und Energie, Berlin — 3Max-Born-Institut, Berlin
We use the time-resolved polar magneto-optical Kerr effect to measure the laser-induced magnetization precession of a 20 nm and 200 nm thin nickel film for different external magnetic field angles. We identify the role of quasi-static strain, strain pulses, and demagnetization for driving the precession in these samples. The magnetization response is modeled using the udkm1Dsim toolbox, which calculates the temperature, strain, and subsequent magnetization response with a modified Landau-Lifshitz-Gilbert equation that incorporates demagnetization. Contributions from the demagnetization-induced change in anisotropy, quasi-static strain, and propagating strain pulses are included in the time-dependent effective field. In the case of nickel, the quasi-static strain drives the effective field in the opposite direction to the demagnetization-induced change in anisotropy. For the samples and fluences measured, we identify the laser-induced strain and the subsequent change in the magnetoelastic field as the dominant mechanism controlling the precession. In a subsequent double-pulse excitation experiment, we balance the effect of the demagnetizationinduced change in anisotropy and the magnetoelastic contribution in a non-conventional coherent control scheme.
Keywords: Precession; Demagnetization; Magnetoelastic; trMOKE; Nickel