Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices

Anthony K C Tan,Charles Reichhardt,James Lourembam,Lisen Huang,Hang Khume Tan,Anjan Soumyanarayanan,Pin Ho,Cynthia J O Reichhardt

doi:10.1038/s41467-021-24114-8

Abstract

Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices.

Highlights

Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements
Using magnetic force microscopy (MFM) imaging, we examine over 20,000 instances of skyrmion motion over a range of applied currents and fields, spanning three distinct dynamic regimes: stochastic creep, deterministic creep and plastic flow
This work was performed at room temperature (RT) on [Pt(3)/Co(1.2)/MgO(1.5)]15 multilayer films sputtered on Si/SiO2 substrates and patterned into 2 μm wide wire devices

Summary

Introduction

Magnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices. Skyrmion dynamics in sputtered multilayer wires may be affected on one hand by material granularity and defects[29,30], and on the other by interactions with the wire edge[31,32] These extrinsic effects are yet to be experimentally understood. Our results and insights establish a robust experimental framework to realize high-throughput skyrmion motion in wire devices for next-generation nanoelectronics

Methods

Results

Conclusion