Topological Spin Textures in Chiral Magnets

Chiral magnets are materials in which a lack of spatial inversion symmetry gives rise to an antisymmetric exchange interaction that promotes the formation of non-collinear spin configurations. Among these, magnetic skyrmions and hopfions represent distinct classes of topological solitons. Skyrmions appear as two-dimensional swirling vortices of magnetisation that can extend through the thickness of a sample to form tubular strings. Hopfions are their three-dimensional counterparts, realised by twisting and closing a skyrmion string into a loop. The stability of these structures is endowed by a quantised topological charge, rendering them robust against moderate perturbations and making them promising candidates for energy‐efficient spintronic devices. Recent advances have elucidated nucleation pathways, manipulation strategies using electric currents and thermal gradients, and three-dimensional imaging techniques. Progress in both bulk crystals and multilayer systems has deepened our understanding of topological transitions, defect interactions and dynamical responses, paving the way towards practical applications in data storage, logic architectures and neuromorphic computing.

Research from Nature Portfolio

Recent studies have directly observed hopfion rings in single crystals of a cubic chiral magnet using transmission electron microscopy. By coupling Lorentz imaging with electron holography and micromagnetic simulations, researchers have demonstrated reproducible nucleation and a unified homotopy classification of skyrmion–hopfion transformations. In another development, three-dimensional skyrmion strings in MnSi have been dynamically bent under orthogonal thermal gradients, revealing magnon friction effects and suggesting an additional degree of freedom for skyrmion manipulation. Complementing these insights, small-angle neutron scattering tomography has provided bulk visualisation of a disordered skyrmion lattice in Co8Zn8Mn4, uncovering monopole-driven branching and segmentation pathways that underpin topological transitions in three dimensions.

Topological Spin Textures in Chiral Magnets publication trend

The graph below shows the total number of articles in topological spin textures in chiral magnets across all publications each year (not limited to Nature Index journals).

Technical terms

Skyrmion: A two-dimensional topological spin vortex characterised by a continuous magnetisation winding that forms tubular strings in three dimensions.

Hopfion: A closed three-dimensional topological soliton formed by twisting and looping a skyrmion string, carrying an integer linking number.

Chiral magnet: A magnetic material lacking inversion symmetry, in which the Dzyaloshinskii–Moriya interaction stabilises non-collinear spin textures.

Dzyaloshinskii–Moriya interaction: An antisymmetric exchange interaction favouring orthogonal spin alignment and the formation of rotating magnetisation structures.

Topological charge: A quantised integer (or half-integer) that measures the winding or linking of a spin texture, conferring stability against continuous deformations.

References

1. Hopfion rings in a cubic chiral magnet. Nature (2023).
2. Bending skyrmion strings under two-dimensional thermal gradients. Nature Communications (2024).
3. Three-dimensional neutron far-field tomography of a bulk skyrmion lattice. Nature Physics (2023).
4. Realization and Current‐Driven Dynamics of Fractional Hopfions and Their Ensembles in a Helimagnet FeGe. Advanced Materials (2023).
5. Soft X-Ray Phase Nanomicroscopy of Micrometer-Thick Magnets. Physical Review X (2024).