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MA: Fachverband Magnetismus
MA 59: Posters Magnetism III
MA 59.17: Poster
Freitag, 20. März 2020, 09:00–12:00, P2/EG
Current-induced instabilities of magnetic skyrmions due to spin-transfer torques; speed limits for skyrmions — Jan Masell1,2, •Benjamin F. McKeever3, Davi R. Rodrigues3, and Karin Everschor-Sitte3 — 1Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany — 2RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan — 3Institute of Physics, Johannes Gutenberg-Universität, 55128 Mainz, Germany
Magnetic skyrmions in chiral ferromagnets can be efficiently moved by spin-polarized electric currents, and controllable motion at high speeds is particularly desirable for spintronics applications. Upon increasing the current strength, however, skyrmions deform from their trademark circular shape, which limits their utility. We analyze single skyrmions in motion for different micromagnetic parameters and driving currents, due to spin-transfer torques for smooth magnetic textures, and systematically map out how the skyrmion shape distorts. For compact skyrmions at uniaxial anisotropies far above the critical anisotropy for a uniform ground state, we find that at large current densities the skyrmion assumes a non-circular shape with a tail, reminiscent of a shooting star. For larger, softer, skyrmions closer to the critical anisotropy, we observe a critical current density above which skyrmions become unstable and elongate to an arbitrary extent; however, above a second critical current density the shooting star solution can also be recovered for these skyrmions.
[1] J. Masell, B.F. McKeever et al. (in preparation), (2020)