Current-driven transformations of a skyrmion tube and a bobber in stepped nanostructures of chiral magnets.

Magnetic skyrmion tubes and bobbers are two types of different nanoscale spin configurations that can coexist in nanostructures of chiral magnets. They are then proposed to be utilized as binary bits to build racetrack memory devices. The ability to manipulate the two magnetic objects controllably by current in nanostructures is the prerequisite to realize the device. Here, we demonstrate by numerical simulations that a magnetic bobber and a skyrmion tube can be transformed to each other using spin-polarized current in nanostripes with stepped shape. We also show such stepped nanostructures can be readily applied as the write head for the skyrmion-bobber-based racetrack memory. [ABSTRACT FROM AUTHOR]