Current-driven dynamics of magnetic solitons: magnetic skyrmions and vortex-antivortex pairs

Abstract

Magnetic solitons, such as domain wall, vortices, Bloch lines and skyrmions have started to play an important role in modern magnetism. These solitons offer exceptional stability, making them promising for memory and logic devices. This study focuses on experimental findings related to dynamic magnetic solitons, particularly magnetic skyrmions and vortex antivortex pairs. We examine the scaling behavior of weakly driven magnetic skyrmions and compare it to that of magnetic domain wall creep. Surprisingly, skyrmions exhibit a hopping behavior rather than following the scaling law observed in the creep of domain walls. This behavior persists even when the topological charge of the skyrmion is removed. The hopping behavior arises from a bottleneck process induced by domain wall segments with diverging collective lengths in closed-shape spin structures. The study reveals that the structural topology of magnetic textures determines the universality class of their weakly driven motion, distinct from that of magnetic domain wall creep [1]. Additionally, we explore the current-driven dynamics of magnetic vortex-antivortex pairs, highlighting the generation and movement of multiple pairs using spin transfer torque. Furthermore, it indicates that magnetic vortices are more mobile than magnetic antivortices. The topological aspects of vortex-antivortex pair dynamics are also discussed. The findings contribute to a better understanding of the behaviour of magnetic solitons and their potential applications in various devices.