Characterization of microscopic ferromagnetic defects in thin films using magnetic microscope based on Nitrogen-Vacancy centres

TL;DR

This paper demonstrates the use of a nitrogen-vacancy center-based magnetic microscope to characterize microscopic ferromagnetic defects in thin films, providing detailed magnetic field maps and potential for quality control in manufacturing.

Contribution

The study introduces a magnetic imaging technique using NV centers for detailed defect characterization in thin films, with potential for high-throughput quality control.

Findings

Identified ferromagnetic impurity islands affecting magnetic properties.

Mapped magnetic field amplitude and distribution of defects.

Correlated magnetic maps with optical images for comprehensive analysis.

Abstract

In this work we present results acquired by applying magnetic field imaging technique based on Nitrogen-Vacancy centres in diamond crystal for characterization of magnetic thin films defects. We used the constructed wide-field magnetic microscope for measurements of two kinds of magnetic defects in thin films. One family of defects under study was a result of non-optimal thin film growth conditions. The magnetic field maps of several regions of the thin films created under very similar conditions to previously published research revealed microscopic impurity islands of ferromagnetic defects, that potentially could disturb the magnetic properties of the surface. The second part of the measurements was dedicated to defects created post deposition - mechanical defects introduced in ferromagnetic thin films. In both cases, the measurements identify the magnetic field amplitude and distribution of the magnetic defects. In addition, the magnetic field maps were correlated with the corresponding optical images. As this method has great potential for quality control of different stages of magnetic thin film manufacturing process and it can rival other widely used measurement techniques, we also propose solutions for the optimization of the device in the perspective of high throughput.