Nanoscale magnetometry of a synthetic three-dimensional spin texture

TL;DR

This paper demonstrates the use of nitrogen-vacancy scanning probe microscopy to perform quantitative, non-invasive nanoscale vector-field magnetometry on complex 3D spin textures in synthetic antiferromagnets, revealing detailed magnetic properties.

Contribution

It introduces the first quantitative vector-field magnetometry of multilayered synthetic antiferromagnets using NV-SPM under ambient conditions, enabling detailed analysis of nanoscale spin textures.

Findings

Detected GHz-range spin noise and stray fields of several mT.

Revealed domain and domain wall structures at the nanoscale.

Provided insights into thermal spin-wave magnetic noise.

Abstract

Multilayered synthetic antiferromagnets (SAFs) are artificial three-dimensional (3D) architectures engineered to create novel, complex, and stable spin textures. Non-invasive and quantitative nanoscale magnetic imaging of the two-dimensional stray field profile at the sample surface is essential for understanding the fundamental properties of the spin-structure and being able to tailor them to achieve new functionalities. However, the deterministic detection of spin textures and their quantitative characterization at the nanoscale remain challenging. Here, we use nitrogen-vacancy scanning probe microscopy (NV-SPM) under ambient conditions to perform the first quantitative vector-field magnetometry measurements in the multilayered SAF [(Co/Pt)$_5$/Co/Ru]$_3$/(Co/Pt)$_6$. We investigate nanoscale static and dynamic properties of antiferromagnetic domains with boundaries hosting ``one-dimensional'' ferromagnetic stripes with ~ 100 nm of width and periodic modulation of the magnetization. By employing NV-SPM measurements in different imaging modes and involving NV-probes with various crystallographic orientations, we demonstrated distinct fingerprints emerging from GHz-range spin noise and constant stray fields on the order of several mT. This provides quantitative insights into the structure of domains and domain walls, as well as, into magnetic noise associated with thermal spin-waves. Our work opens up new opportunities for quantitative vector-field magnetometry of modern magnetic materials with tailored 3D spin textures and stray field profiles, and potentially novel spin-wave dispersions--in a quantitative and non-invasive manner, with exceptional magnetic sensitivity and nanometer scale spatial resolution.