For both fundamental and application points of view, the switching time and behavior of a trilayer system consisting of a ferromagnetic/nonmagnetic/ferromagnetic trilayer is of utmost significance. In microstructured magnetic multilayer systems a clear view of the reversal dynamics has not yet been achieved experimentally because a technique is needed that offers at the same time a high temporal and lateral resolution. Time-resolved x-ray magnetic circular dichroism photoelectron emission microscopy (XMCD-PEEM) represents a state-of-the-art way of getting ultrafast time resolution in the low picosecond regime and simultaneously layer and spatially resolved magnetic information.
The local magnetization dynamics of different magnetic microstructures was studied at BESSY using this technique. Ultra-short magnetic field pulses were provided by electric current pulses flowing through a gold stripline underneath the microstructures, triggered by an optical switch by means of femtosecond laser pulses. This part of the technique, in combination with the length of the synchrotron bunch, is responsible for the time resolution of the experiment. Magnetic field pulses as short as 100 ps FWHM with rise times below the resolution of the synchrotron pulses of 50 ps have been obtained. The transient magnetic response of the sample is detected at fixed pump-probe delay times between the exciting field pulses and the detecting x-ray pulses, and the results compared to micromagnetic simulations.
Results were obtained in collaboration with J. Miguel, J. Kurde, J. Sanchez-Barriga, D. Bayer, B. Heitkamp, M. Piantek, F. Kronast, R. Weber, M. Aeschlimann, H. A. DŸrr, and L. Tati-Bismaths.
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