Symmetry and curvature effects on spin waves in vortex-state hexagonal nanotubes
| Autor: | István Kézsmárki, Markus Weigand, Lukas Körber, Helmut Schultheiss, Simone Finizio, Jörg Raabe, Sebastian Wintz, Michael Zimmermann, Christian H. Back, M. Kronseder, Jorge A. Otálora, Florian Dirnberger, Elisabeth Josten, Dominique Bougeard, Jürgen Lindner, Attila Kákay |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physics
Condensed Matter - Materials Science Condensed Matter - Mesoscale and Nanoscale Physics Condensed matter physics Hexagonal crystal system ddc:530 STXM Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Large scale facilities for research with photons neutrons and ions micromagnetic modeling hexagonal Curvature 530 Physik Vortex state Symmetry (physics) Spin wave curvature Mesoscale and Nanoscale Physics (cond-mat.mes-hall) dispersion spin wave symmetry |
| Zdroj: | Physical Review B 104(2021), 184429 Physical review / B 104(18), 184429 (2021). doi:10.1103/PhysRevB.104.184429 |
| DOI: | 10.1103/PhysRevB.104.184429 |
| Popis: | Analytic and numerical studies on curved magnetic nano-objects predict numerous exciting effects that can be referred to as magneto-chiral effects, which do not originate from intrinsic Dzyaloshinskii–Moriya interaction or interface-induced anisotropies. In constrast, these chiral effects stem from isotropic exchange or dipole-dipole interaction, present in all magnetic materials, which acquire asymmetric contributions in case of curved geometry of the specimen. As a result, for example, the spin-wave dispersion in round magnetic nanotubes becomes asymmetric, namely spin waves of the same frequency propagating in opposite directions along the nanotube exhibit different wavelenghts. Here, using time-resolved scanning transmission X-ray microscopy experiments, standard micromagntic simulations and a dynamic-matrix approach, we show that the spin-wave spectrum undergoes additional drastic changes when transitioning from a continuous to a discrete rotational symmetry, i.e. from round to hexagonal nanotubes, which are much easier to fabricate. The polygonal shape introduces localization of the modes both to the sharp, highly curved corners and flat edges. Moreover, due to the discrete rotational symmetry, the degenerate nature of the modes with azimuthal wave vectors known from round tubes is partly lifted, resulting in singlet and duplet modes. For comparison with our experiments, we calculate the microwave absorption from the numerically obtained mode profiles which shows that a dedicated antenna design is paramount for magnonic applications in 3D nano-structures. To our knowledge these are the first experiments directly showing real space spin-wave propagation in 3D nano objects. |
| Databáze: | OpenAIRE |
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