Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 20: POSTER Ib
MA 20.13: Poster
Tuesday, March 17, 2015, 09:30–13:00, Poster A
Laser induced meta-stable magnetic structures probed by Lorentz microscopy — •Marcel Möller1, Jan Gregor Gratzmann1, Armin Feist1, Nara Rubiano da Silva1, Vladyslav Zbarsky2, Markus Münzenberg3, Claus Ropers1, and Sascha Schäfer1 — 1IV. Physical Institute, University of Göttingen, 37077 Göttingen, Germany — 2I. Physical Institute, University of Göttingen, 37077 Göttingen, Germany — 3Institut fur Physik, Greisfwald University, 17489 Greifswald, Germany
Ultrashort laser excitation allows for an all-optical control of magnetic structures [1]. On the micrometer-scale, laser-induced magnetic changes can be imaged using, for example, Faraday microscopy.
Here, we employ in-situ Lorentz microscopy to study meta-stable magnetic structures generated by femtosecond optical pulse pairs with variable polarization states. As a first example, we investigate homogenous iron thin-films and observe an optically triggered switching of ripple domains at low excitation fluence. For laser pulse energies above a well-defined threshold, new meta-stable magnetic structures are formed, consisting of a dense network of vortices and antivortices with a charateristic correlation length of about 500 nm. Furthermore, we present first results using Lorentz microscopy in an ultrafast transmission electron microscope (UTEM) utilizing sub-picosecond electron pulse probing.
[1] Mangin, S., et al. "Engineered materials for all-optical helicity-dependent magnetic switching." Nature materials 13.3 (2014): 286-292.