%0 Journal Article
%A Zheng, Fengshan
%A Kiselev, Nikolai S.
%A Rybakov, Filipp N.
%A Yang, Luyan
%A Shi, Wen
%A Blügel, Stefan
%A Dunin-Borkowski, Rafal E.
%T Hopfion rings in a cubic chiral magnet
%J Nature
%V 623
%N 7988
%@ 0028-0836
%C London [u.a.]
%I Nature Publ. Group
%M FZJ-2023-04806
%P 718 - 723
%D 2023
%X Magnetic skyrmions and hopfions are topological solitons1—well-localized field configurations that have gained considerable attention over the past decade owing to their unique particle-like properties, which make them promising objects for spintronic applications. Skyrmions2,3 are two-dimensional solitons resembling vortex-like string structures that can penetrate an entire sample. Hopfions4,5,6,7,8,9 are three-dimensional solitons confined within a magnetic sample volume and can be considered as closed twisted skyrmion strings that take the shape of a ring in the simplest case. Despite extensive research on magnetic skyrmions, the direct observation of magnetic hopfions is challenging10 and has only been reported in a synthetic material11. Here we present direct observations of hopfions in crystals. In our experiment, we use transmission electron microscopy to observe hopfions forming coupled states with skyrmion strings in B20-type FeGe plates. We provide a protocol for nucleating such hopfion rings, which we verify using Lorentz imaging and electron holography. Our results are highly reproducible and in full agreement with micromagnetic simulations. We provide a unified skyrmion–hopfion homotopy classification and offer insight into the diversity of topological solitons in three-dimensional chiral magnets.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 37993571
%U <Go to ISI:>//WOS:001169158300012
%R 10.1038/s41586-023-06658-5
%U https://juser.fz-juelich.de/record/1018431