IMPROVEMENT OF REPRODUCIBILITY OF MAGNETIC MOMENT DETECTED BY A SQUID MAGNETOMETER THROUGH RADIAL OFFSET MEASUREMENT ON A YIG SPHERE

Published

September 19, 2018

Author(s)

Cindi L. Dennis, Robert D. Shull, Nobuhiro Matsumoto

Abstract

We report here on the reproducibility of measurements on a commercial SQUID Magnetometer of two different yttrium iron garnet (YIG) spheres, both having a diameter of 1 mm: (1) the NIST magnetic moment standard reference material (SRM) and (2) a commercial sample. It has been suggested that rotating the sample rod around its axis can move the sample center towards the center of the second-gradiometer coil. The observed value of the magnetic moment will be theoretically a minimum when the radial offset is zero and this value will increase in a “quadratic” manner with the radial offset. When the magnetic moment of the SRM was repeatedly measured as a function of rotation angle ϕ from 0o to 360o, we observed a sinusoidal variation in the measured values. The radial offset dependence of the observed magnetic moment was experimentally confirmed by measurements of the commercial sphere placed in a hole in several cylindrical PTFE containers, wherein the distance between the center of the hole and the center of the container was r. The r dependence of the minimum from each ϕ-dependent measurement series is qualitatively consistent with the theoretical curve. When the ϕ-dependent measurements for the SRM in a capsule were repeated 12 times over 21 months, the relative standard deviation of the minimums improved up to 0.1%. Knowledge of these facts will be necessary for accurate measurement of the magnetic moment of other sample forms (e.g., powders).

Citation

IEEE Transactions on Magnetics

Pub Type

Journals

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Keywords

SQUID, reproducibility, YIG, calibration

Citation

Dennis, C. , Shull, R. and Matsumoto, N. (2018), IMPROVEMENT OF REPRODUCIBILITY OF MAGNETIC MOMENT DETECTED BY A SQUID MAGNETOMETER THROUGH RADIAL OFFSET MEASUREMENT ON A YIG SPHERE, IEEE Transactions on Magnetics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926214 (Accessed November 21, 2024)