Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 19: Spin-Dynamics/Switching I
MA 19.10: Talk
Wednesday, March 28, 2007, 17:30–17:45, H23
Slow recovery of magnetic anisotropy following ultrafast optical excitation of a spin-reorientation transition — •Thomas Eimüller1, Andreas Scholl2, Edward Amaladass3, Bernd Ludescher3, Gisela Schütz3, Michael Binder4, and Christian Back4 — 1Ruhr-University of Bochum, Junior Research Group Magnetic Microscopy — 2Advanced Light Source, LBNL, Berkeley, CA, USA — 3Max-Planck-Institute for Metals Research, Stuttgart — 4University of Regensburg, Experimental and Applied Physics
Multilayered Fe/Gd systems, showing a spin reorientation transition (SRT) from in-plane to out-of-plane magnetization with rising temperature, have been studied by x-ray photoemission electron microscopy (X-PEEM). We found a continuous, i.e., second order transition between in-plane and out-of-plane domains, with a coexistence of both types in a temperature interval of about 25 K. The dynamics of this SRT has been investigated in an optical pump - x-ray-probe experiment. A short laser pulse raises the temperature of the sample by about 25 K. By scanning the delay time between 0 and 8 ns the dynamic response of the Fe and Gd magnetic moments has been recorded with X-PEEM, resulting in a temporal resolution below 100 ps and a spatial resolution below 100 nm. We found large time dependent XMCD effects generated by a damped spin precession, superposed to a slow relaxation (> 8 ns) of the easy axis back into the sample plane. This relaxation is way longer than the measured and simulated heat diffusion time and may shade new light into the transport of torque form the spin into the lattice system.