SKM 2021 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Posters Magnetism IV

MA 15.15: Poster

Donnerstag, 30. September 2021, 13:30–16:30, P

Wavelength-dependent magnetization dynamics in Ni|Au bilayers — •Christopher Seibel, Marius Weber, Martin Stiehl, Sebastian T. Weber, Martin Aeschlimann, Benjamin Stadtmüller, Hans Christian Schneider, and Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, Germany

Existing experimental and theoretical studies of ultrafast demagnetization in ferromagnets rely mostly on only one fixed wavelength to excite the sample. However, recent experiments indicate that the dynamics of the demagnetization and remagnetization process depend on the wavelength of the exciting laser pulse [V. Cardin et al., Phys. Rev. B 101, 054430 (2020); U. Bierbrauer et al., JOP: Cond. Mat. 29, 244002 (2017)].

We extend the temperature-based µ T-model to describe the ultrafast magnetization dynamics of magnetic/non-magnetic bilayer systems. Our theoretical model relies on realistic densities of states of both materials. It includes energy and spin transfer at the interface as well as the layer and wavelength dependent absorption of the pump pulses.

For the exemplary case of a thin nickel layer on a gold substrate, we find a faster and larger loss of the magnetic order of Ni when increasing the wavelength from 360 nm to 800 nm. Our theoretical predictions are confirmed by time-resolved MOKE experiments. This allows us to discuss the influence of energy and spin transfer processes for the photon energy dependent magnetization dynamics of magnetic bi- and multilayer structures.