Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 23: Non-ultrafast magnetization dynamics
MA 23.3: Vortrag
Mittwoch, 14. März 2018, 10:00–10:15, H 0112
Analysis of magnetoelastic coupling in Co-Pt multilayer systems — •Norbert Weinkauf1, Peter Gaal1, Raanan Tobey2, Chia-Lin Chang2, and Hans Peter Oepen1 — 1Institute of Nanostructure and Solid State Physics, University of Hamburg, Germany — 2Faculty of Science and Engineering, University of Groningen, the Netherlands
We have measured optically excited magnetization precession on thin, in-plane Co-Pt multilayer systems on glass substrate. Using a three-temperature model the fast energy transfer from the electron and spin system to the lattice few picoseconds after optical excitation is explained. The initial lattice temperature after excitation is significantly lower than the Curie temperature of Cobalt. Hence we assume that demagnetization and the subsequent precession is instantly driven by shear strain and not heat. In addition we derive a quantitative model by the analytical solution of the Landau-Lifshitz equation.
Furthermore we use transient grating excitation on the same cobalt multilayers. The time-resolved measurement of Faraday rotation and of the diffraction from the transient grating yields information about the magnetoelastic coupling. Two distinct resonances were detected, one assigned to a surface acoustic wave, one to surface skimming longitudinal wave. These can be calculated by a parametric oscillator model and the Landau-Lifshitz equation.
In addition, similar measurements were performed for Co-Pt multilayer systems on 500nm SiNi-membranes. We observe distinct differences in the acoustic mode spectrum compared to bulk substrates.