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MA: Fachverband Magnetismus
MA 10: Magnetization Dynamics I
MA 10.7: Vortrag
Montag, 14. März 2011, 16:15–16:30, HSZ 403
Cherenkov-like spin wave emission by supermagnonic domain walls in ferromagnetic nanotubes — •Christian Andreas1, Ming Yan1, Attila Kákay1, Felipe Garcia-Sanchez1, and Riccardo Hertel1,2 — 1Institut für Festkörperforschung, Elektronische Eigenschaften, Forschungszentrum Jülich GmbH — 2Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504
The micromagnetic structure of vortex walls in nanotubes is comparable to that of
transverse walls in thin strips, since the orientation
of transverse walls corresponds to the vorticity of vortex walls
in nanotubes [1]. In spite of this similarity of their static structures,
we found that the dynamic properties of these domain walls (DWs) differ significantly.
Unlike DWs in thin strips, the
left-right symmetry of DW mobility is broken. While head-to-head DWs with left-handed chirality lead to a Walker breakdown [2] above a limiting velocity, those with right-handed chirality can reach propagation velocities beyond the phase velocity of spin waves (about 1000 m/s). As soon as the minimum spin-wave phase velocity is reached, tails
of spin waves are formed in front of and behind the DW. Such a spontaneous emission of spin waves is analogous to Cherenkov radiation emitted by charged particles moving in a dielectric medium at velocities above the speed of light. The moving DW with attached spin-wave tails reaches a dynamic equilibrium
and propagates as a topological soliton afterwards.
R. Hertel et al., J. Magn. Magn. Mater. 278 291 (2004)
N. L. Schryer and L. R. Walker, J. Appl. Phys. 45, 5406 (1974)