Avalanches and Criticality in Driven Magnetic Skyrmions

Area of Science:

• Condensed matter physics
• Complex systems

Background:

• Skyrmions are topological spin textures with potential applications in data storage.
• Their motion in disordered media is crucial for understanding their behavior.

Purpose of the Study:

• To investigate the dynamics of driven Skyrmions interacting with random pinning.
• To analyze the statistical properties of Skyrmion avalanches.
• To explore the influence of the Magnus term on Skyrmion motion.

Main Methods:

• Numerical simulations of Skyrmion dynamics.
• Analysis of avalanche size, duration, and shape distributions.
• Investigation of the effect of varying the Magnus term to damping ratio.

Main Results:

• Skyrmion motion occurs via correlated jumps or avalanches.
• Avalanches follow power-law distributions for duration and size.
• Average avalanche shape scales to a universal function, indicating a nonequilibrium critical state.
• Increasing the Magnus term alters the universality class and leads to asymmetric avalanches.
• Individual avalanches exhibit motion perpendicular to their density gradient.

Conclusions:

• Skyrmion dynamics in random pinning exhibit critical behavior analogous to other driven systems.
• The Magnus term plays a significant role in modifying Skyrmion dynamics and universality class.
• These findings provide insights into the fundamental physics of topological defects in magnetic materials.