Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Magnetization Dynamics I of 3
MA 33.3: Vortrag
Donnerstag, 14. März 2013, 10:00–10:15, H22
Tuning the timescale of ultrafast demagnetization in GdTb alloys through spin-lattice coupling — •Andrea Eschenlohr1,2, Muhammad Sultan1, Nicolas Bergeard1, Alexey Melnikov3, Jens Wieczorek1, Torsten Kachel2, Christian Stamm2, and Uwe Bovensiepen1 — 1Fakultät für Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen — 2Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH — 3Fritz-Haber-Institut der MPG, Berlin
Pure Gd and Tb show femtosecond laser-induced demagnetization in two steps, with the time constant of the second, slower step depending on the strength of coupling of the 4f magnetic moments to the lattice [Wietstruk et al., PRL 106, 127401 (2011)]. In time-resolved magneto-optical Kerr effect measurements on GdTb alloys, we see a decrease of this time constant from 33 ps to 9 ps with Tb content increasing from 0 to 70 %, due to the strong spin-lattice coupling of Tb. In time- and element-resolved x-ray magnetic circular dichroism measurements at the BESSY II Femtoslicing source concomitant dynamics of the Gd and Tb magnetization components is observed, revealing an increased coupling of the Gd 4f magnetic moments to the lattice via indirect exchange coupling to the neighboring Tb 4f moments, so that demagnetization of Gd in the alloy is accelerated compared to the pure material.
We acknowledge funding from BMBF Grant 05K10PG2 Femtospex and the DAAD-HEC Pakistan.