Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 16: Skyrmions I
MA 16.9: Talk
Tuesday, March 10, 2026, 11:45–12:00, HSZ/0004
Isolated Magnetic Hopfions — Xiaowen Chen1, •Nikolai S. Kiselev2, Filipp N. Rybakov3, Donghai Yang1, and Fengshan Zheng1 — 1South China University of Technology, Guangzhou, China — 2Forschungszentrum Jülich, Germany — 3Uppsala University, Sweden
Hopfions are three-dimensional topological solitons formed by closed loops of vortex strings. In magnetic crystals, hopfions have so far been observed only in unusual configurations in which they are linked to skyrmion strings [1]. Although theory predicts the existence of stable, isolated hopfions in frustrated magnets [2] and chiral magnets [3], their experimental realization has remained elusive. Here we report laser-induced nucleation and direct TEM observation of isolated magnetic hopfions in the B20-type FeGe crystal [4]. We map out the nucleation conditions as a function of laser fluence and external magnetic field. Good agreement between experimental data and micromagnetic simulations unambiguously confirms the emergence of isolated hopfions and reveals their detailed structure. We derive the relevant topological invariant for hopfions embedded in helical or conical backgrounds and calculate its integer values for the observed objects. We demonstrate that these hopfions are stable without geometrical confinement and can coexist and interact with other topological spin textures. [1] F. Zheng, et al., Nature 623, 718 (2023). [2] F. N. Rybakov et al., APL Mater. 10, 111113 (2022). [3] J.-S. B. Tai & I. I. Smalyukh, Phys. Rev. Lett. 121, 187201 (2018). [4] X. Chen, et al., preprint on Research Square https://doi.org/10.21203/rs.3.rs-7435743/v1
Keywords: hopfion,; skyrmion; topological soliton