Topological pumping of bimerons in spiral magnets

TL;DR

This paper demonstrates that spiral magnets can naturally and precisely position bimerons using a rotating magnetic field, enabling topologically protected, quantized transport without engineered pinning sites, advancing skyrmion racetrack technology.

Contribution

The study introduces a novel method for topologically protected, quantized transport of bimerons in spiral magnets driven by a rotating magnetic field, eliminating the need for engineered pinning landscapes.

Findings

Bimerons can be displaced by exactly one spiral period per rotation.

Transport of bimerons is topologically protected and robust.

The method enables precise, energy-efficient positioning of spin textures.

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.