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MA: Fachverband Magnetismus

MA 27: Magnetization / Demagnetization Dynamics I

MA 27.3: Vortrag

Mittwoch, 18. März 2015, 10:00–10:15, EB 301

Laser-induced ultrafast demagnetization of Co₂MnGa Heusler alloy probed by femtosecond XMCD in reflection geometry — •Sergej Solopow¹, Alexander Kronenberg², Martin Jourdan², Loic Le Guyader¹, Niko Pontius¹, Torsten Kachel¹, Hans-Joachim Elmers², Ilie Radu¹, and Alexander Föhlisch¹ — ¹Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany — ²Institut für Physik Johannes Gutenberg Universität, Staudingerweg 7, 55128 Meinz, Germany

Being equally a science- and technologically-driven topic, the research on ultrafast demagnetization dynamics has witnessed an intense activity over the past decades. However, its microscopic origin remains highly elusive and equally debated. In this context, the half-metallic Heusler alloys are particularly interesting due to their peculiar band structure i.e. they are metallic for majority electrons while exhibiting a band gap for the minority ones. Here we report on ultrafast demagnetization investigations of the Co₂MnGa alloy using time-resolved XMCD in reflection geometry at the slicing facility of BESSY II Berlin. Upon tuning the pumping wavelength from visible to near-IR we were able to photo-excite k-specific and spin-selective electronic states and thus to trigger a band structure-specific demagnetization dynamics. The subsequent optical and magnetic responses of the alloy have been recorded for both Co and Mn elements, showing an intriguingly fast dynamics.