Controlled Formation of Skyrmion Bags

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Magnetic skyrmions are topologically non-trivial spin textures with potential applications.
• Stabilizing complex, higher-order magnetic skyrmion textures beyond simple skyrmions has been a significant challenge.

Purpose of the Study:

• To experimentally demonstrate the stabilization of isolated higher-order skyrmion bags in ferromagnetic thin films.
• To investigate methods for controlled generation of various skyrmion bag types with different topological charges.

Main Methods:

• Artificial anisotropy defects were engineered using local ion irradiation.
• Field- and ultrafast laser-induced nucleation of skyrmion bags were employed.
• High-resolution X-ray imaging and micromagnetic simulations were used for observation and analysis.

Main Results:

• Controlled generation of skyrmionium (2π), target skyrmions (3π), and variable topological charge skyrmion bags was achieved.
• Engineered defects acted as preferential nucleation sites.
• Ultrafast laser pulses showed a higher conversion rate for skyrmion bag formation compared to magnetic fields.
• Defect geometry, particularly diameter, was crucial for stabilizing closed-loop domain textures.

Conclusions:

• The study successfully stabilized and characterized complex magnetic skyrmion bags.
• Engineered defects provide a pathway for controlling topological spin textures.
• Findings expand experimental possibilities for skyrmion research and suggest applications in spintronics.