Modulated Magnetic Nanowires for Controlling Domain Wall Motion: Toward 3D Magnetic Memories

TLDR

Cylindrical magnetic nanowires promise high domain‑wall velocity and dense fabrication, but effective control requires reliable, well‑defined pinning sites. The study demonstrates that alternating Ni and Co sections in modulated nanowires enable efficient domain‑wall pinning at their interfaces. Electron holography, micromagnetic simulations, and differential phase contrast imaging reveal that stray‑field interactions at Ni/Co interfaces pin domain walls, producing a 3‑D vortex structure with a Bloch point. The results confirm that Ni/Co modulated nanowires pin domain walls efficiently, creating a 3‑D vortex with a Bloch point and indicating promise for high‑density 3‑D magnetic memory.

Abstract

Cylindrical magnetic nanowires are attractive materials for next generation data storage devices owing to the theoretically achievable high domain wall velocity and their efficient fabrication in highly dense arrays. In order to obtain control over domain wall motion, reliable and well-defined pinning sites are required. Here, we show that modulated nanowires consisting of alternating nickel and cobalt sections facilitate efficient domain wall pinning at the interfaces of those sections. By combining electron holography with micromagnetic simulations, the pinning effect can be explained by the interaction of the stray fields generated at the interface and the domain wall. Utilizing a modified differential phase contrast imaging, we visualized the pinned domain wall with a high resolution, revealing its three-dimensional vortex structure with the previously predicted Bloch point at its center. These findings suggest the potential of modulated nanowires for the development of high-density, three-dimensional data storage devices.