Magnetic skyrmion bundles and their current-driven dynamics

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological charge (Q) is crucial for classifying non-trivial spin textures like skyrmions.
• Existing research primarily focuses on textures with |Q| ≤ 1, such as skyrmions and vortices.
• Multi-Q three-dimensional spin textures remain largely unexplored.

Purpose of the Study:

• To create and characterize novel magnetic skyrmion bundles, which are multi-Q three-dimensional spin textures.
• To investigate the dynamics of these bundles under electric current.
• To understand the influence of topological charge on their motion and associated phenomena.

Main Methods:

• Real-space imaging techniques were employed to create and observe magnetic skyrmion bundles.
• Experimental manipulation using electric currents was used to induce collective motion.
• Measurements of the skyrmion Hall effect were performed for bundles with varying topological charges.

Main Results:

• Successfully created and imaged magnetic skyrmion bundles with integer Q values up to 55.
• Demonstrated that electric currents drive the collective motion of these particle-like textures.
• Observed a significant skyrmion Hall effect (~62°) for bundles with Q ≠ 0, while Q=0 bundles (skyrmioniums) showed collinear motion (~0°).

Conclusions:

• The experimental observation of multi-Q skyrmion bundles expands the family of magnetic topological textures.
• These novel textures exhibit distinct dynamic behaviors influenced by their topological charge.
• The findings suggest potential applications for multi-Q spin textures in future spintronic devices.