Current-direction-controlled dynamics of skyrmion bags guided by a domain wall barrier

Skyrmion bags—composite spin textures consisting of a host skyrmion enclosing multiple inner skyrmions—are promising candidates for high-density magnetic storage. Due to the opposite topological charges of the host and inner skyrmions, their dynamics are considerably richer than those of isolated skyrmions. In this work, we find that during free motion, the Hall angle is nearly independent of the number of enclosed skyrmions N, for bags with nonzero total topological charge, with this near-independence becoming particularly pronounced in the large-N regime. To suppress the skyrmion Hall effect, we introduce a domain-wall barrier to guide the bag motion. When the current flows parallel to the domain wall, the bag velocity is independent of N; when perpendicular, the velocity increases monotonically with N. Thus, by tuning the current injection angle, the bag velocity can be continuously adjusted, while bags with smaller N exhibit greater stability against annihilation. Our results are in good agreement with Thiele-analysis predictions and may provide guidance for the design of skyrmion-based spintronic devices.