A geometry-independent moment correction method for the Magnetic Property Measurement 3 Superconducting Quantum Interference Device-Vibrating Sample Magnetometer

TL;DR

This paper introduces a new correction method for SQUID magnetometers that eliminates the need for detailed sample geometry information, simplifying accurate magnetic moment measurements especially for irregular samples.

Contribution

A novel, geometry-independent correction method for SQUID magnetometers that does not require precise sample shape or size data.

Findings

The correction method is validated with measurements of metallic Fe powder.

It shows a systematic relation between VSM and DC measurements independent of sample geometry.

The method improves measurement accuracy for irregularly shaped samples.

Abstract

The sensitivity and automation capabilities of modern superconducting quantum interference device (SQUID) magnetometers are currently unmatched. The measured moment values are, however, prone to deviations from their actual value due to geometric effects, namely sample size, shape, and radial offset. This is well known, and a knowledgeable operator will correct measured moment values taking these effects into account. The current procedure for the Magnetic Property Measurement 3 (MPMS3) magnetometer is based on an available simulation tool, valid for both Vibrating Sample Magnetometer (VSM) and Direct Current (DC) methods. Still, determining the correction factor requires samples with well-defined geometric shapes together with accurate sample dimensions and the usually difficult to determine radial offset. Additionally, at the moment, there is not a proper solution to correct geometry effects of irregular shaped samples. In this work, we find a systematic relation between the difference between the VSM and DC measurements and their corresponding correction factors for MPMS3 SQUID-VSM device. This relation follows a clear trend, independent of sample size, shape or radial offset, for a given pair of DC scan length and VSM amplitude values. Exploiting this trend, a geometry-independent correction method is here presented and validated by measurements of metallic Fe powder using a far from optimal sample mounting.