Embedded Skyrmion Bags in Thin Films of Chiral Magnets

• Published in: Advanced materials (Weinheim) 2024-09, Vol.36 (36), p.e2403274-n/a
• Main Authors: Yang, Luyan, Savchenko, Andrii S., Zheng, Fengshan, Kiselev, Nikolai S., Rybakov, Filipp N., Han, Xiaodong, Blügel, Stefan, Dunin‐Borkowski, Rafal E.
• Format: Article
• Language: English
• Subjects: chiral magnet; Cube texture; Cubic lattice; Electron spin; Hypothetical particles; Magnetic fields; magnetic imaging; Magnetic properties; Magnets; Metastable state; Particle spin; Particle theory; skyrmion; Solitary waves; Stability; Thin films; Thin plates; Topology; transmission electron microscopy; Two dimensional analysis
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202403274

Magnetic skyrmions are topologically nontrivial spin configurations that possess particle‐like properties. Earlier research has mainly focused on a specific type of skyrmion with topological charge Q = −1. However, theoretical analyses of 2D chiral magnets have predicted the existence of skyrmion bags—solitons with arbitrary positive or negative topological charge. Although such spin textures are metastable states, recent experimental observations have confirmed the stability of isolated skyrmion bags in a limited range of applied magnetic fields. Here, by utilizing Lorentz transmission electron microscopy, the extraordinary stability of skyrmion bags in thin plates of B20‐type FeGe is shown. In particular, it is shown that skyrmion bags embedded within a skyrmion lattice remain stable even in zero or inverted external magnetic fields. A robust protocol for nucleating such embedded skyrmion bags is provided. The results agree perfectly with micromagnetic simulations and establish thin plates of cubic chiral magnets as a powerful platform for exploring a broad spectrum of topological magnetic solitons. This work reports the first experimental observations of magnetic skyrmion bags embedded within skyrmion lattices in thin plates of B20‐type FeGe. By utilizing Lorentz transmission electron microscopy, the extraordinary stability of embedded skyrmion bags, which remain stable even in zero or inverted external magnetic fields, is observed directly. A robust protocol for nucleating such embedded skyrmion bags is provided.