Magnetism
XFEL investigations of ultrafast surface dynamics in magnetic materials
The properties of magnetic materials can be changed on time scales of 100 fs by an external stimulus such as IR laser pulses. We employ resonant magnetic scattering experiments at XFEL sources to investigate the spatial evolution of the spin system after IR laser excitation. Here we make use of the fact that X-ray photons when tuned to dichroic resonances can probe the magnetic state of a sample. We are especially interested in the spatial evolution of spin densities at surfaces or interfaces of magnetic materials which are currently being investigated in a DFG funded project.
Schematics of a pump-probe experiment. The sample is excited with a 70 fs IR pulse. A time delay dt later, the FEL radiation probes the properties of the excited state. The diffraction ring on the camera contains information about the structural properties of the sample.
B. Pfau et al.
Nature Communications 3, 1100 (2012)
Measurements of ultrafast spin-profiles and spin-diffusion properties in the domain wall area at a metal/FM film interfaceT. Sant, D. Ksenzov, F. Capotondi, E. Pedersoli, M. Manfredda, M. Kiskinova, H. Zabel, M. Kläui, J. Lüning, U. Pietsch and C. Gutt
Scientific Reports 7, 15064 (2017)
We are also interested in the nanoscale dynamics of hard condensed matter systems such as ferroelectric or magnetic materials. Here we study the (often intermittent) dynamics associated with the motion of domain walls under applied external stimuli such as electric fields or temperature.
Ferroelectric domain wall dynamics characterized with X-ray photon correlation spectroscopy
S. Gorfman, A. Bokov, A. Davtyan, M. Reiser, Y. Xie, Y. Ye, A. Zozulya, M. Sprung, U. Pietsch and C. Gutt
Proceedings of the National Academy of Science – PNAS 115 (29), 6680 (2018)
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