Current-driven motion of magnetic domain-wall skyrmions

Abstract: Domain-wall skyrmions (DWSKs) are topological spin textures confined within domain walls that have recently attracted significant attention due to their potential applications in racetrack memory technologies. In this study, we theoretically investigated the motion of DWSKs driven by spin-polarized currents in ferromagnetic strips. Our findings reveal that the motion of DWSKs is contingent upon the direction of the current. When the current is applied parallel to the domain wall, both spin-transfer torque (STT) and spin-orbit torque (SOT) can drive the DWSK along the domain wall. Conversely, for currents applied perpendicular to the domain wall, STT can induce DWSK motion by leveraging the skyrmion Hall effect as a driving force, whereas SOT-driven DWSKs halt their motion after sliding along the domain wall. Furthermore, we demonstrated the current-driven motion of DWSKs along curved domain walls and proposed a racetrack memory architecture utilizing DWSKs. These findings advance the understanding of DWSK dynamics and provide insights for the design of spintronic devices based on DWSKs.