Spin-Wave Emission from Vortex Cores under Static Magnetic Bias Fields

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2021-02-24

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en

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7

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Nano Letters, Volume 21, issue 4, pp. 1584−1590

Abstract

We studied the influence of a static in-plane magnetic field on the alternating-field-driven emission of nanoscale spin waves from magnetic vortex cores. Time-resolved scanning transmission X-ray microscopy was used to image spin waves in disk structures of synthetic ferrimagnets and single ferromagnetic layers. For both systems, it was found that an increasing magnetic bias field continuously displaces the wave-emitting vortex core from the center of the disk toward its edge without noticeably altering the spin-wave dispersion relation. In the case of the single-layer disk, an anisotropic lateral expansion of the core occurs at higher magnetic fields, which leads to a directional rather than radial-isotropic emission and propagation of waves. Micromagnetic simulations confirm these findings and further show that focusing effects occur in such systems, depending on the shape of the core and controlled by the static magnetic bias field.

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Funding Information: We would like to thank Joachim Gräfe, Michael Bechtel and Joe Bailey for their support during the STXM beamtimes, Matthias Kronseder and Christian Back for their help with the sample fabrication, and Roland Mattheis for providing the magnetron sputter deposition of the SFi. The STXM measurements were carried out at the MAXYMUS end station of the BESSY II synchrotron radiation facility of Helmholtz-Zentrum Berlin. We thank HZB for the allocation of synchrotron radiation beamtime. Additional measurements were performed at the PolLux end station at SLS, PSI, Villigen PSI, Switzerland. The PolLux end station was financed by the German Ministerium für Bildung und Forschung (BMBF) through contracts 05K16WED and 05K19WE2. This project received funding from the Swiss National Science Foundation (Grant Agreement 172517). A.H. was funded by the European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie Grant Agreement 794207 (ASIQS). Publisher Copyright: © 2020 American Chemical Society. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

magnetization dynamics, magnonics, spin waves, vortex cores, X-ray microscopy

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Citation

Mayr, S, Flajšman, L, Finizio, S, Hrabec, A, Weigand, M, Förster, J, Stoll, H, Heyderman, L J, Urbánek, M, Wintz, S & Raabe, J 2021, ' Spin-Wave Emission from Vortex Cores under Static Magnetic Bias Fields ', Nano Letters, vol. 21, no. 4, pp. 1584−1590 . https://doi.org/10.1021/acs.nanolett.0c03740