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MA: Fachverband Magnetismus

MA 20: POSTER Ib

MA 20.12: Poster

Tuesday, March 17, 2015, 09:30–13:00, Poster A

Ultrafast Magnetization Dynamics of Gd and Tb studied by XMCD — •Kamil Bobowski¹, Robert Carley^1,2, Björn Frietsch¹, Markus Gleich¹, Martin Teichmann^1,2, Christoph Trabant¹, Marko Wietstruk¹, and Martin Weinelt¹ — ¹Fachbereich Physik der Freien Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — ²European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany

Our recent time- and angle-resolved photoemission study [1] questions the ultrafast Gd 4f spin dynamics measured previously on sandwiched polycrystalline Gd films using X-ray magnetic circular dichroism (XMCD) in transmission [2]. To answer this question, we performed pump-probe experiments on single-crystalline Gd combining optical excitation and femtosecond XMCD in reflection. In a first preparatory beamtime, we showed the feasibility of this experiment by measuring simultaneously the reflection and absorption signal while varying the temperature from 100 K to above the Curie temperature. For comparative measurements, a Tb sample was investigated in the same way. Furthermore, we present preliminary results of the magnetization dynamics of the Gd 4f spins which were measured at the FEMTOSPEX beamline at BESSY II.

[1] B. Frietsch et. al., submitted.

[2] M. Wietstruk et. al., Phys. Rev. Lett. 106 25, 127401 (2011).