Confinement-controlled pathways to complex skyrmionic textures in Co/W/Pt multilayers

TL;DR

This study demonstrates how geometric confinement in Pt/Co/W multilayers can deterministically control the formation and transformation of complex skyrmionic textures at room temperature, enabling new spintronic applications.

Contribution

It reveals that geometric confinement acts as a universal control parameter for hierarchical transformation pathways of chiral spin textures in multilayer micro-tracks.

Findings

Labyrinth domains fragment into isolated skyrmions with increased confinement.

Skyrmioniums form via recombination and evolve into skyrmion bags in narrow tracks.

Skyrmion bags become the dominant state in the narrowest micro-tracks.

Abstract

Magnetic skyrmions and higher-order topological spin textures offer rich opportunities for multi-level information encoding, yet their deterministic stabilization and transformation under geometric confinement at room temperature remain poorly understood. Here, we demonstrate that geometric confinement acts as a robust and universal control parameter that governs a hierarchical transformation pathway of chiral spin textures in Pt/Co/W multilayer micro-tracks. As the confinement increases, extended labyrinth domains fragment into isolated skyrmions, followed by the systematic suppression of skyrmion pairs and the preferential stabilization of compact higher-order textures. We find that confinement strongly enhances the formation of skyrmioniums via recombination and promotes their subsequent evolution into uniform skyrmion bags by capturing additional skyrmions. Statistical analysis reveals a confinement-driven redistribution of topological populations, with skyrmion bags emerging as the dominant state in the narrowest tracks. Supported by micromagnetic simulations, our results establish geometric confinement as a deterministic selector of complex topological textures and reveal a previously unexplored route for engineering higher-order skyrmionic states at room temperature. These findings provide a scalable materials strategy for multistate skyrmion-based spintronic and memory architectures.