Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 20: POSTER Ib
MA 20.11: Poster
Dienstag, 17. März 2015, 09:30–13:00, Poster A
Altering the spin wave frequency spectra in vortex structures by simultaneous excitations of the vortex gyromode — •Markus Härtinger1, Hans G. Bauer1, Hermann Stoll2, and Christian Back1 — 1Department of Physics, University of Regensburg, 93040 Regensburg, Germany — 2Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
In nano-sized ferromagnetic disks recent experiments and micromagnetic simulations of simultaneous excitations of both, the gyromode and spin wave modes, result in a significant reduction of the vortex core (VC) switching threshold[1]. By micromagnetic simulations H.G. Bauer et al.[2] revealed that two frequency excitation below the switching-threshold results in a frequency splitting of the lowest spin wave mode.
Here we report on an experimental verification by VNA-FMR measurements of the frequency spectrum of the azimuthal spin waves when the sub-GHz gyromode is resonantly excited simultaneously in Ni80 Fe20 disks, 1.6 µ m in diameter. Without excitation of the gyromode, the first two magnetostatic spin wave modes (n=1, m=±1) are observed at about 5 GHz and 6.5 GHz. After additional simultaneous excitation at the gyromode eigenfrequency (about 250 MHz) we observe a decrease and broadening of the lower frequency spin wave absorption peak for the increased gyro-excitation amplitude as predicted by micromagnetic simulations[2].
[1] M. Sproll et al. Appl. Phys. Lett. 104, 012409 (2014)
[2] H.G. Bauer et al. Phys. Rev. Lett. 112, 077201 (2014)