Berlin 2018 – scientific programme
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MA: Fachverband Magnetismus
MA 43: Magnetic textures I
MA 43.1: Talk
Thursday, March 15, 2018, 09:30–09:45, EB 407
Topological defects and emergent electromagnetism in cylindrical nanowires — •Michalis Charilaou1, Hans-Benjamin Braun2, and Jörg F. Löffler1 — 1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich — 2School of Physics, University College Dublin
Magnetic switching in nanoparticles, particularly with cylindrical symmetry, is associated with curling-type processes but conventional wisdom neglects topological constraints that preclude a continuous complete reversal. In this work [1] we present evidence that in cylindrical nanowires the process of athermal magnetization switching is initiated by the formation of smooth topological defects in the form of skyrmion lines. As long as the magnetization evolves continuously the switching is prevented by the skyrmion lines, effectively acting like radial exchange springs. Switching becomes irreversible only after a skyrmion line breaks into a pair of hedgehogs, which move along the wire. Importantly, the movement of the hedgehogs produces an emergent electric field of circular polarization and substantial magnitude. Hence, by considering a generic case of cylindrical magnetic particles we show that irreversibility is directly linked to the formation and dynamics of topological point-defects.
[1] M. Charilaou, H.-B. Braun, J. F. Löffler, arXiv:1711.03511