Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 34: Magnetization / Demagnetization Dynamics III
MA 34.3: Vortrag
Mittwoch, 28. März 2012, 15:30–15:45, H 1012
Vortex core reversal by pulsed orthogonal magnetic fields of 100 ps duration and below — •Matthias Noske1, Markus Weigand1, Matthias Kammerer1, Markus Sproll1, Ajay Gangwar2, Hermann Stoll1, Georg Woltersdorf2, and Gisela Schütz1 — 1MPI for Intelligent Systems, Stuttgart — 2Department of Physics, Regensburg University
Recently it was demonstrated that the magnetic vortex core can be unidirectionally switched by exciting azimuthal spin wave modes at frequencies in the multi-GHz range [1]. Compared to core reversal by using the sub-GHz vortex gyromode [2], the increased excitation frequencies allow for shorter switching times. In the present talk we will demonstrate how to speed up spin wave mediated vortex core reversal down to 100 ps by applying pulsed orthogonal magnetic fields. Experiments have been performed by time-resolved scanning transmission X-ray microscopy at the MAXYMUS endstation at BESSY II, Berlin. At micron sized Permalloy discs unidirectional vortex core switching could be achieved at an excitation time of 135 ps. On smaller samples switching was achieved at 105 ps excitation time, but in this case the vortex core reversal was found not to be unidirectional. The experimental findings correspond to our micromagnetic simulations which show a strong dependence on sample geometry. In addition, our simulations indicate that unidirectional vortex core reversal will be feasible at excitation times of less than 100 ps for certain sample geometries.
[1] M. Kammerer et al., Nature Communications 2, 279 (2011)
[2] B. Van Waeyenberge et al., Nature 444, 461 (2006)