Stochastic skyrmion dynamics under alternating magnetic fields

Magnetic skyrmions are topological spin textures that have attracted significant attention owing to their diverse physical characteristics. Recently, various applications utilizing the Brownian motion of skyrmions have been reported. However, the diffusion of skyrmions is suppressed by pinning sites in magnetic thin films, which can limit computing speed. In this paper, we explore the stochastic dynamics and diffusion coefficient of skyrmions under a perpendicular alternating current (AC) magnetic field. The skyrmion diffusion coefficient increased exponentially as the AC magnetic field was increased owing to the stretching motion of the string-shaped skyrmions. This study may provide a technological framework for the realization of low-power-consumption Brownian devices.