Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 19: Spin-Dynamics/Switching I
MA 19.6: Talk
Wednesday, March 28, 2007, 16:30–16:45, H23
Picosecond spin dynamics of Gd(0001) studied by linear dichroism of 4f shell. A time-resolved experiment combined laser and synchrotron radiation — •Helena Prima Garcia1, Alexev Melnikov2, Martin Lisowski2, Roland Schmidt1, Uwe Bovensiepen2, and Martin Weinelt1,2 — 1Max-Born-Institute, Berlin, Germany. — 2Freie Universität , Berlin, Germany
We have studied ultrafast magnetization dynamics in Gd(0001) films alignment by time-resolved X-ray photoemission spectroscopy. Absorption of a 50 fs laser-pump-pulse at 800 nm leads to optical excitation of the Gd valence electrons. We probe the relaxation dynamics by linear dichroism in photoemission from the Gd 4f electrons using a 60 eV, 50 ps probe-pulse at the synchrotron user facility BESSY, Germany. Linear dichroism in photoemission is proportional to the magnetic moment of the 4f7 electrons. The breakdown of the magnetic ordering upon fs laser excitation has been reported based on magneto-optical studies to occur within 100 fs. The recovery of the equilibrium magnetization is driven by cooling of the lattice and spin-lattice interaction. It proceeds on a 100 ps time scale [2]. Here we show the breakdown of the magnetic moment after laser excitation within the probe pulse duration and the subsequent recovery to the equilibrium value. As linear dichroism is a measure of the alignment of the Gd 4f moments, its breakdown is a further proof of laser-induced desmagnetization.
[1] Oleg Krupin, Phd thesis, Fachbereich Physik Freie Universität Berlin, Germany.
[2] A. Vaterlaus, et.al. Phys. Rev. Lett. 67, (1991) 3314.