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MA: Fachverband Magnetismus

MA 45: Magnetic Relaxation and Gilbert Damping

MA 45.5: Vortrag

Donnerstag, 12. März 2026, 10:30–10:45, POT/0351

Thickness-dependent modulation of magnetization dynamics in ultralow-damping Co₂MnSi Heusler alloys measured by ultrafast TR-MOKE — •Levi Geier¹, Anulekha De¹, Anna Maria Friedel^1,2, Philipp Pirro¹, Martin Aeschlimann¹, and Georg von Freymann^1,3 — ¹RPTU University Kaiserslautern-Landau — ²Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54000 Nancy, France — ³Fraunhofer Institute for Industrial Mathematics ITWM, Kaiserslautern

We measure the laser-induced ultrafast demagnetization and subsequent damped precession of the magnetization dynamics in Co₂MnSi Heusler alloys of varying thicknesses (4 nm - 18 nm). The study is performed by a time-resolved magneto-optical Kerr effect (TR-MOKE) setup based on an all-optical pump-probe approach. An ultralow effective damping down to an effective Gilbert damping constant α = 0.004 is measured for the 18-nm-thick sample, which increases with decreasing applied magnetic field and increasing pump fluence. We attribute this trend to the generation of incoherent magnons in addition to the coherent magnons after excitation by the laser pulse. Moreover, we observe a strong dependence of the effective damping parameter on the film thickness. The effective damping decreases significantly with increasing film thickness, presumably due to two-magnon scattering. Interestingly the quenching of the magnetization during the demagnetization does not change significantly with pump fluence.

Keywords: TR-MOKE; Heusler Alloys; Damping; Precession; Demagnetization