Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 12: Superconductivity – Topological Defects in Superconductors and Magnets (joint session TT/MA)
MA 12.1: Vortrag
Montag, 12. März 2018, 15:00–15:15, HFT-FT 101
Topological domain walls in helimagnets — •Laura Köhler1, Peggy Schönherr2, Jan Müller3, Naoya Kanazawa4, Yoshinori Tokura4,5, Achim Rosch3, Dennis Meier6, and Markus Garst1 — 1Institut für Theoretische Physik, TU Dresden, Dresden, Germany — 2Department of Materials, ETH Zürich, Zürich, Switzerland — 3Institut für Theoretische Physik, Universität zu Köln, Köln, Germany — 4Department of Applied Physics, University of Tokyo, Tokyo, Japan — 5RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan — 6Department of Materials Science and Engineering, NTNU, Trondheim, Norway
The Dzyaloshinskii-Moriya interaction in chiral magnets stabilizes a magnetic helix with a wavelength set by the spin-orbit coupling. We study domain walls of helimagnetic order both theoretically and experimentally using micromagnetic simulations and magnetic force microscopy studies on surfaces of FeGe. We find that such domain walls are distinctly different from those in ferromagnets and rather similar to grain boundaries of liquid crystals. Three
types of domain walls are realized depending on the relative domain orientation: a curvature wall, a zig-zag disclination wall and a dislocation wall. Disclinations are vortex defects in the helix axis orientation, and they can be combined to form dislocations. We discuss the topological skyrmion charge associated with these dislocations which can be finite. This leads to an emergent electrodynamics and thus a coupling to spin currents as well as to a contribution to the topological Hall effect.
P. Schönherr et al. arXiv1704.06288 (2017).