Realizing high-velocity skyrmions via anisotropy engineering

Abstract

Skyrmion-based racetrack memories are expected to be operated by the motion of skyrmions through magnetic nano-wires made of metallic multi-layers with high spin–orbit coupling and Dzyaloshinskii–Moriya interaction. The current-driven skyrmions in a ferromagnetic system had limitations due to their higher Hall angles and lower velocity. We addressed this by interfacial anisotropy engineering, which helped us to stabilize skyrmions at a thickness of x = 0.65 nm of Cu in the HM–FM interface of perpendicularly magnetized Ta3nmPt3nmCuxCo0.5nmPt1nm. At x = 0.60 nm Cu, the system showed worm like structures, while at 0.70 nm of Cu, the system showed in-plane magnetization. This system with optimum magnetic anisotropy enabled one to achieve skyrmions with a velocity of 260 m/s and low skyrmion Hall effect at room temperature with driving current <3×1011A/m2.