Sunday, July 21, 2013

1307.4548 (Markus Sproll et al.)

Low-amplitude magnetic vortex core reversal by non-linear interference
between azimuthal spin waves and the vortex gyromode

Markus Sproll, Matthias Noske, Hans Bauer, Matthias Kammerer, Ajay Gangwar, Georg Dieterle, Markus Weigand, Hermann Stoll, Christian H. Back, Gisela Schütz
We demonstrate a non-linear interference due to an active 'dual frequency' excitation of both, the sub-GHz vortex gyromode and multi-GHz magneto-static spin waves in ferromagnetic micrometer sized platelets in the vortex state. When the sub-GHz vortex gyromode is excited simultaneously a significant broadband reduction of the switching threshold for spin wave mediated vortex core reversal is observed in both, experiments and micromagnetic simulations. Consequently, the magnetic field amplitudes required for vortex core reversal can be lowered by nearly one order of magnitude. Moreover, additional spin wave resonance frequencies are found which emerge only if the vortex gyromode is actively excited simultaneously which can be explained by frequency doubling and by the broken symmetry of the vortex state.
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