TY  - JOUR
AU  - Zheng, Fengshan
AU  - Kiselev, Nikolai S.
AU  - Rybakov, Filipp N.
AU  - Yang, Luyan
AU  - Shi, Wen
AU  - Blügel, Stefan
AU  - Dunin-Borkowski, Rafal E.
TI  - Hopfion rings in a cubic chiral magnet
JO  - Nature
VL  - 623
IS  - 7988
SN  - 0028-0836
CY  - London [u.a.]
PB  - Nature Publ. Group
M1  - FZJ-2023-04806
SP  - 718 - 723
PY  - 2023
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - 37993571
UR  - <Go to ISI:>//WOS:001169158300012
DO  - DOI:10.1038/s41586-023-06658-5
UR  - https://juser.fz-juelich.de/record/1018431
ER  -