Nano-engineering the evolution of skyrmion crystal in synthetic antiferromagnets

TL;DR

This paper demonstrates the tunable evolution of artificial skyrmion crystals in synthetic antiferromagnets, enabling control over skyrmion behaviors and multiple stable states for potential spintronic applications.

Contribution

It introduces a method to control skyrmion nucleation, deformation, and annihilation in nanostructured multilayers, advancing skyrmion-based device development.

Findings

Skyrmion nucleation and annihilation are controllable via nanodot size and spacing.

Increasing bottom layer thickness shifts skyrmion annihilation from ferromagnetic to antiferromagnetic textures.

Multiple non-volatile states are achieved at zero magnetic field.

Abstract

The evolution of skyrmion crystal encapsulates skyrmion critical behaviors, such as nucleation, deformation and annihilation. Here, we achieve a tunable evolution of artificial skyrmion crystal in nanostructured synthetic antiferromagnet multilayers, which are comprised of perpendicular magnetic multilayers and nanopatterned arrays of magnetic nanodots. The out-of-plane magnetization hysteresis loops and first-order reversal curves show that the nucleation and annihilation of the artificial skyrmion can be controlled by tuning the diameter of and spacing between the nanodots. Moreover, when the bottom layer thickness increases, the annihilation of skyrmion shifts from evolving into a ferromagnetic spin texture to evolving into an antiferromagnetic spin texture. Most significantly, non-volatile multiple states are realized at zero magnetic field via controlling the proportion of the annihilated skyrmions in the skyrmion crystal. Our results demonstrate the tunability and flexibility of the artificial skyrmion platform, providing a promising route to achieve skyrmion-based multistate devices, such as neuromorphic spintronic devices.