Bias-Engineered Synthetic Antiferromagnets Hosting sub-20 nm Zero-Field Skyrmions at Room Temperature

TL;DR

This paper introduces a novel synthetic antiferromagnetic bias system that stabilizes sub-20 nm zero-field skyrmions at room temperature, advancing spintronic device potential.

Contribution

The study presents a new SAF bias system enabling stable, zero-field skyrmions and demonstrates the smallest SAF skyrmions reported to date through experimental and modeling techniques.

Findings

Reliable zero field skyrmion formation demonstrated.

Sub-20 nm SAF skyrmions directly observed.

SAF bias system suppresses domain formation and maintains uniform exchange field.

Abstract

Synthetic antiferromagnetic skyrmions (SAFsk) are nanoscale, topologically protected spin textures with strong potential for spintronic technologies because of their high stability and the absence of the skyrmion Hall effect. However, robust zero field stabilization remains a central challenge. Here, a synthetic antiferromagnetic (SAF) bias system is introduced as a novel strategy to stabilize both ferromagnetic skyrmions (FMsk) and SAFsk at zero field. Ferromagnetic (FM) and SAF multilayers are designed, fabricated and integrated with the SAF bias system to enable controlled skyrmion stabilization and polarity setting via multilayer design and a preparatory field cycle. Combining quantitative and high-sensitivity magnetic force microscopy (MFM) with micromagnetic modeling, reliable zero field skyrmion formation is demonstrated and sub 20nm SAFsk are directly observed, the smallest SAFsk reported to date. Moreover, the SAF bias system concept introduced here offers a robust and scalable route to bias future skyrmion multilayers, as its compensated nature suppresses domain formation and preserves a uniform exchange field.