SKM 2021 – scientific programme
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MA: Fachverband Magnetismus
MA 5: Posters Magnetism II
MA 5.13: Poster
Tuesday, September 28, 2021, 10:00–13:00, P
Real-Space Observation of Topological Defects in Extended Skyrmion-Strings — •Jan Masell1, Xiuzhen Yu1, Fehmi S. Yasin1, Kosuke Karube1, Naoya Kanazawa2, Kiyomi Nakajima1, Takuro Nagai3, Koji Kimoto3, Wataru Koshibae1, Yasujiro Taguchi1, Naoto Nagaosa1,2, and Yoshinori Tokura1,2 — 1RIKEN CEMS, Wako, Japan — 2University of Tokyo, Tokyo, Japan — 3National Institute for Materials Science, Tsukuba, Japan
Skyrmions are whirls in the magnetization which are characterized by a 2d topological winding number. Due to their topology, large skyrmions are protected by a high energy barrier [1] which makes them interesting objects for potential future applications. However, in 3d bulk materials or thin films, skyrmions are strings (SkS) which can have singular topological defects [2], known as Bloch points.
We use Lorentz Transmission Microscopy (LTEM) on thin films of chiral magnets to obtain a sideview of SkS that extend in the film plane. We obtain high resolution images of various defects, including Bloch points which terminate SkS or fuse them, but also SkS which annihilate smoothly by escaping through the surface. These objects can be discerned by comparing them to the results of micromagnetic simulations. [3]
[1] B. Heil, A. Rosch & J. Masell, Phys. Rev. B 100, 134424 (2019)
[2] P. Milde et al., Science 340, 1076-1080 (2013)
[3] X.Z. Yu*, J. Masell* et al., Nano Lett. 20, 7313-7320 (2020)