Measurements of magnetic materials

Major methods to measure the magnetic properties of materials are systematically discussed in the light of the general phenomenology of magnetism in matter and its physical interpretation. Attention is paid to the problems of measurement traceability and reproducibility and the related standards. While the discussion is focused on the characterization of the soft and hard ferromagnetic materials relevant for electromagnetic applications, brief consideration is given to the special problems posed by measurements on feebly magnetic materials. It is stressed how geometrical and physical properties can often combine to make the determination of the true magnetic properties of materials a somewhat elusive goal. Measurement reproducibility can nevertheless be attained under the guidance provided by written standards. Recent evolution of the magnetic measuring techniques has occurred in response to the digital revolution and the development of novel high-performance materials (e.g. extra-hard rare-earth based magnets, multilayers, micro/nanostructures, etc). It is stressed, however, that the drive to progress in measurements ultimately stems from the search for new fundamental phenomena in materials and their understanding.