Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.37: Poster
Freitag, 4. April 2014, 10:30–13:30, P2
Ultrafast magnetization dynamics probed by Lorentz microscopy with temporally structured illumination — •Jan Gregor Gatzmann1, Vladyslav Zbarsky2, Markus Münzenberg2, Sascha Schäfer1, and Claus Ropers1 — 1IV. Physikalisches Institut, Universität Göttingen — 2I. Physikalisches Institut, Universität Göttingen
Combining transmission electron microscopy (TEM) with ultrashort sample excitation allows for the observation of ultrafast dynamics at the nanoscale. Whereas ultrafast laser-pump/ electron-probe experiments were recently developed, the benefits of temporally structured illumination with femtosecond pulse trains in a conventional TEM remain rather unexplored. Here, we use Lorentz microscopy to study the irreversible magnetization dynamics in iron thin-films triggered by femtosecond optical pulses. At low excitation fluence, we observe a laser-induced switching of ripple domains, with characteristic patterns shaped by pinned domain walls. At a well-defined fluence threshold, the generation of magnetic vortex-antivortex networks is initiated. The dynamical nature of these processes is investigated utilizing femtosecond pulse pairs with variable delay times.