Analysing Magnetism Using Scanning SQUID Microscopy

TL;DR

This paper discusses methods to improve quantitative analysis of magnetic fields using scanning SQUID microscopy, focusing on spatial resolution, data interpretation, and potential future applications.

Contribution

It provides a detailed analysis of interpreting SSM images, explores factors affecting spatial resolution, and introduces autocorrelation analysis for characterizing magnetic features.

Findings

Signal evolution with scan height and device parameters

Autocorrelation analysis reveals feature size and shape

Guidelines for quantitative SSM data interpretation

Abstract

Scanning superconducting quantum interference device microscopy (SSM) is a scanning probe technique that images local magnetic flux, which allows for mapping of magnetic fields with high field and spatial accuracy. Many studies involving SSM have been published in the last decades, using SSM to make qualitative statements about magnetism. However, quantitative analysis using SSM has received less attention. In this work, we discuss several aspects of interpreting SSM images and methods to improve quantitative analysis. First, we analyse the spatial resolution and how it depends on several factors. Second, we discuss the analysis of SSM scans and the information obtained from the SSM data. Using simulations, we show how signals evolve as a function of changing scan height, SQUID loop size, magnetization strength and orientation. We also investigated 2-dimensional autocorrelation analysis to extract information about the size, shape and symmetry of magnetic features. Finally, we provide an outlook on possible future applications and improvements.