A geometry-independent moment correction method for the MPMS3 SQUID-based magnetometer

Modern superconducting quantum interference device (SQUID) magnetometers enable fully automated measurements with currently unmatched sensitivity. The measured moment values are, however, prone to deviations from their actual value due to geometric effects, namely sample size, shape, and radial offset. The current procedure to correct these geometric effects, for the magnetic property measurement 3 (MPMS3) magnetometer, is based on an available simulation tool, valid for both SQUID-VSM and DC-scan 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. There is no established solution to correct geometry effects of irregularly shaped samples or unknown radial offsets. In this work, we find a systematic relation between the difference of SQUID-VSM and DC-scan measurements and their corresponding correction factors for the MPMS3. This relation follows a clear trend, independent of sample geometry and radial offset, for a given pair of DC-scan length and SQUID-VSM amplitude values. Exploiting this trend, a geometry-independent correction method is presented and validated by measurements of two different geometries of the same Al piece, two different radial offsets of a Ni square, and metallic Fe powder using a far from optimal sample mounting.

Automated summary

This study presents a geometry-independent correction method for magnetic moment measurements, based on a systematic relation between the differences of SQUID-VSM and DC-scan measurements and their respective correction factors. The method is applicable to samples of different shapes and radial offsets, and has been validated by experimental measurements on various samples.