Topological pumping of bimerons in spiral magnets

Abstract

Precise positioning of topological defects is essential for racetrack memories, where their positions along a magnetic nanotrack encode information. Traditional methods achieve nanometric precision by engineering pinning landscapes that enforce discrete steps in defect motion. However, accessing each bit requires overcoming a depinning threshold, which increases power consumption. Here, we demonstrate that spiral magnets provide a natural ruler, enabling precise positioning of bimerons (topological spin textures analogous to skyrmions) without relying on engineered pinning sites. A rotating magnetic field couples directly to the bimeron position, displacing it by exactly one spiral period per full rotation of the field. Such quantized transport of skyrmionic textures, reminiscent of Thouless pumping, is topologically protected and remains robust against perturbations, positioning spiral magnets as a natural skyrmion racetrack. The findings establish a paradigm for topologically protected transport of spin textures.