Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 11: Ultrafast magnetism II
MA 11.7: Vortrag
Montag, 12. März 2018, 16:45–17:00, EB 407
Influence of the stoichiometry in ferromagnetic alloys on the ultrafast demagnetization — •Simon Häuser1, Moritz Hofherr1, Jurij Urbancic1, Sakshath Sadashivaiah1, Sebastian Weber1, Justin Shaw2, Tom Silva2, Hans Nembach3, Daniel Steil2, Henry Kapteyn3, Margaret Murnane3, Mirko Cinchetti4, Bärbel Rethfeld1, Benjamin Stadtmüller1, Stefan Mathias2, and Martin Aeschlimann1 — 1University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany — 2Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 3Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA — 4Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
We investigate time- and element-resolved the fs demagnetization dynamics in a ferromagnetic Fe50Ni50 alloy using a transverse magnetooptical Kerr effect experiment at the M-edge. After the optical excitation, we observe an instant response of the Fe subsystem while the onset of the Ni demagnetization is delayed by 90fs. While this result is in qualitatively agreement to previous findings for permalloy (Fe20Ni80), the time different between the onsets of demagnetization of Ni and Fe is clearly larger for Fe50Ni50 compared to Fe20Ni80. Our experimental findings will be compared to theoretical model simulations which allows us to gain insight into the role of the transient Ni-Fe exchange coupling for the ultrafast demagnetization dynamics.