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Emergent Self-Propulsion of Skyrmionic Matter in Synthetic Antiferromagnets
Phys. Rev. Lett. 135, 086701 – Published 18 August, 2025
DOI: https://doi.org/10.1103/c2y9-3cc9
Abstract
Self-propulsion plays a crucial role in biological processes and nanorobotics, enabling small systems to move autonomously in noisy environments. Here, we theoretically demonstrate that a bound skyrmion-skyrmion pair in a synthetic antiferromagnetic bilayer can function as a self-propelled topological object, reaching speeds of up to a hundred million body lengths per second—far exceeding those of any known synthetic or biological self-propelled particles. The propulsion mechanism is triggered by the excitation of back-and-forth relative motion of the skyrmions, which generates nonreciprocal gyrotropic forces, driving the skyrmion pair in a direction perpendicular to their bond. Remarkably, thermal noise induces spontaneous reorientations of the pair and momentary reversals of the propulsion, mimicking behaviors observed in motile bacteria and microalgae.
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Viewpoint
Skyrmions as Active Matter
Pairs of skyrmions—tiny whirlpools that emerge in some magnetic materials—might be able to self-propel, a behavior reminiscent of that of active-matter systems such as motile bacteria.
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