Oscillating Grain Boundaries and Their Effects on Grain Growth: Observations in Skyrmion Bicrystals

Grain boundary migration is usually considered to occur through the consistent motion of grain boundaries toward their centers of curvature, ultimately leading to grain growth. However, we show that in 2D skyrmion bicrystals comprising individual grains of hexagonal symmetry, grain boundaries can undergo large amplitude oscillations while maintaining their basic geometric features. Wave-like boundary motion, triggered by individual and collective motion of particles at the grain boundaries, is a behavior that is not accounted for in traditional models of grain boundary migration. Our findings highlight the need for further investigation into the dynamics of grain boundaries during grain growth.