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MA: Fachverband Magnetismus
MA 42: Posters Magnetism I
MA 42.22: Poster
Mittwoch, 18. März 2020, 15:00–18:00, P3
Time-resolved x-ray magnetic circular dichroism on Co/NiMn and Ni/NiMn bilayers — •Ivar Kumberg1, Rahil Hosseinifar1, Sakineh Ghaderi1, Evangelos Golias1, Sangeeta Thakur1, Niko Pontius2, Christian-Schuessler Langeheine2, and Wolfgang Kuch1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Helmholtz-Zentrum Berlin Albert-Einstein-Straße 15, 12489 Berlin, Germany
In order to achieve a better understanding of ultrafast demagnetization processes in coupled systems including transport and exchange coupling effects, we studied stacks of adjacent ferromagnetic and antiferromagnetic layers by time-resolved pump-probe x-ray magnetic circular dichroism. Measurements were done using 60 fs laser pump and 100 fs X-ray probe pulses provided by the FemtoSpeX facility at BESSY II. 15 monolayers (ML) Co/24 ML Ni30Mn70 and 15 ML Ni/15 ML Ni30Mn70 bilayers were grown by molecular beam epitaxy on Cu(001) and growth was monitored by medium-energy electron diffraction and Auger electron spectroscopy.
We interpret our data by using the two- and three-temperature model as well as a phenomenological description following the solution of these models. The aim is to extract the demagnetization times in dependence of temperature, laser fluence, and layer thickness. The demagnetization times are in the range of 100 to 170 fs and follow the expected temperature dependence.