Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 11: Ultrafast magnetism II
MA 11.1: Vortrag
Montag, 12. März 2018, 15:00–15:15, EB 407
Ultrafast Dynamics of Spin and Orbital Moments upon Demagnetization in GdFeCo alloys — •Martin Hennecke1, Ilie Radu1, Radu Abrudan2, Torsten Kachel2, Karsten Holldack2, Rolf Mitzner2, Christian Schüßler-Langeheine2, Arata Tsukamoto3, and Stefan Eisebitt1 — 1Max-Born-Institut, Berlin, Germany — 2Helmholtz-Zentrum Berlin, Germany — 3College of Science and Technology, Nihon University, Funabashi, Chiba, Japan
Recent studies of ferrimagnetic GdFeCo alloys have revealed an ultrafast laser-induced magnetization reversal mediated by a transient ferromagnetic-like state [1]; such switching was purely thermally-driven without the need of any other external stimulus [2]. However, the ultrafast angular momentum transfer from and into the spin system during demagnetization and switching events still remains unclear.
Here, we report on time-resolved XMCD measurements performed at the slicing facility of BESSY II that aim at revealing the angular momentum flow during femtosecond laser-induced demagnetization of ferrimagnetic GdFeCo alloy. The magneto-optical sum rules analysis of the fs-XMCD data allowed us to monitor and disentangle the dynamics of elemental spin and orbital moments at Fe and Gd sites. Within the experimental accuracy, we observe a non-equal magnitude change of spin and orbital momenta on Fe sites during the first hundreds of femtoseconds which suggests a direct transfer of angular momentum to the lattice.
[1] I. Radu et al., Nature 472, 205-208 (2011)
[2] T. Ostler et al., Nature Communications 3, 666 (2012)