Current-driven motion of magnetic domain-wall skyrmions

TL;DR

This paper theoretically explores how magnetic domain-wall skyrmions move under spin-polarized currents, revealing their dependence on current direction and proposing a racetrack memory design utilizing their dynamics.

Contribution

It provides a detailed theoretical analysis of DWSK motion driven by spin torques and introduces a novel racetrack memory architecture based on DWSKs.

Findings

DWSK motion depends on current direction and type of torque.

STT can drive DWSKs along domain walls with current parallel or perpendicular.

SOT-driven DWSKs can halt after sliding along the wall.

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.