Principle for Null Determination of Magnetization and Its Application to Cryogenic Measurements

Abstract

A principle of measurement of magnetization is described which uses a sample in a uniform magnetic field such that the sample does not affect the uniformity of the field and the sample itself is uniformly magnetized. The measurement is absolute in that it requires only a measurement of a current and dimensions. The method uses a cylindrical specimen on which a small pitch fine wire coil is wound. The proper current through the coil required to restore the uniformity of the field in all space gives a direct measurement of the magnetization. Uniformity of the field is detected by an induction technique. The method is suitable for most magnetic measurements but in the case of strongly ferromagnetic materials and superconductors requires currents in the coil that are too large. This principle has been incorporated in an apparatus for measurements of magnetizations from liquid helium temperatures to room temperature.