Formation of zero-field Skyrmion arrays in asymmetric superlattices

TL;DR

This paper reports the creation of metastable zero-field skyrmion arrays in asymmetric multilayer films, influenced by magnetic field application and interfacial interactions, with potential implications for spintronic devices.

Contribution

It demonstrates a method to form and control zero-field skyrmion arrays in multilayer structures using in-plane magnetic fields and interfacial effects.

Findings

Skyrmion arrays are stabilized at zero magnetic field.

The skyrmion texture depends on field strength and orientation.

Opposite polarity skyrmions can coexist in close proximity.

Abstract

We demonstrate the formation of metastable N\'eel-type skyrmion arrays in Pt/Co/Ni/Ir multi-layers at zero-field following \textit{ex situ} application of an in-plane magnetic field using Lorentz transmission electron microscopy. The resultant skyrmion texture is found to depend on both the strength and misorientation of the applied field as well as the interfacial Dzyaloshinskii-Moriya interaction. To demonstrate the importance of the applied field angle, we leverage bend contours in the specimens which coincide with transition regions between skyrmion and labyrinth patterns. Subsequent application of a perpendicular magnetic field near these regions reveals the unusual situation where skyrmions with opposite magnetic polarities are stabilized in close proximity.