Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Poster Session II
MA 48.17: Poster
Donnerstag, 10. März 2016, 15:00–18:00, Poster B1
Ultrafast magnetization dynamics of Gd studied by XMCD in reflection — •Kamil Bobowski1, Björn Frietsch1, Markus Gleich1, Niko Pontius2, Christian Schüßler-Langeheine2, Christoph Trabant1, Marko Wietstruk1, and Martin Weinelt1 — 1Fachbereich Physik der Freien Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany
We studied the ultrafast magnetization dynamics of a 10-nm thick single-crystalline Gd(0001) film at the M4 and M5 absorption edges using X-ray magnetic circular dichroism (XMCD) in reflection geometry. In a laser-pump X-ray-probe experiment we find a two-step demagnetization behavior which shows similar results to earlier XMCD measurements on polycrystalline Gd [1]. On the fast time scale below 4 ps, we observe an exponential decrease of the sample magnetization with increasing pump laser fluence, while on the slow time scale of 100 ps, the demagnetization is linearly dependent on the pump laser fluence. Here, a critical slowing down of the magnetization dynamics is observed for pump pulse fluences above 8 mJ/cm2. A simulation based on the microscopic three temperature model (M3TM) of Koopmans et al. [2] does not allow to quantitatively reproduce the first step of the magnetization dynamics.
[1] M. Wietstruk et. al., Phys. Rev. Lett. 106, 127401 (2011).
[2] B. Koopmans et. al., Nat Mater 9, 259-265 (2010).