Probing 3D topological spin textures via multiple-dimension electron microscopy

Three-dimensional (3D) topological spin textures—such as skyrmion and antiskyrmion strings [1-2], hopfions [3], and monopole–antimonopole pairs [4]—exhibit emergent electromagnetic fields and nonreciprocal dynamics under electrical current excitation [3]. However, their direct experimental observation has remained challenging due to limitations in existing imaging techniques, particularly under cryogenic conditions. Here, we demonstrate cryogenic scalar and vector field electron tomography, which enables 3D mapping of spin textures with nanometer-scale resolution at temperatures well below room temperature [5]. This approach allows direct visualization of twisted skyrmion strings, cryogenically stabilized magnetic hopfions, and toron lattices in chiral magnets [6]. These results represent the first 3D reconstructions of such spin textures in real materials and underscore the capability of cryogenic vector/scalar field tomography to reveal complex internal spin configurations that were previously inaccessible. This work was carried out in collaboration with Yi-Ling Chiew, Nobuto Nakanishi, Fehmi Yashin, Yukako Fujishiro, Naoya Kanazawa, Naoto Nagaosa, and Yoshinori Tokura.

References

1. D. Wolf, et al. Nat. Nanotechnol. 17, 250 (2022).

2. F. Yasin, et al. Adv. Mater. 36, 2311737 (2024).

3. X. Z. Yu, et al. Adv. Mater. 35, 2210646 (2023).

4. C. Donnely, et al. Nature 547, 328 (2017).

5. X.Z. Yu, et al. Commun. Mater. 5, 80 (2024).

6. X. Z. Yu, et al. to be submitted.