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This article provides a summary of the basic properties and the essential phenomenology of application‐oriented soft magnetic materials. Starting from an introductory section, where the magnetization process and the involved energetic aspects are highlighted, the physical rationale for the soft magnetic behavior of the materials is discussed, and a comparative illustration of their main physical, mechanical, and magnetic parameters is provided, the materials are classified according to their composition. We start from pure iron, the historical benchmark for any magnetic material, and pass through the selected alloys and compounds displaying the right combination of properties, including abundance of raw elements and costs, making them attractive for applications. We thus illustrate preparation methods, physical and magnetic properties, and applicative attributes of the following materials: (i) pure iron and low‐carbon steels; (ii) nonoriented and grain‐oriented Fe–Si alloys; (iii) High‐Si, Fe–Al, and Fe–Al–Si alloys; (iv) soft magnetic composites; (v) amorphous alloys; (vi) nanocrystalline alloys; (vii) Ni–Fe and Co–Fe alloys; (viii) soft ferrites. For each material, we summarize (i) compositional features and intrinsic physical and magnetic properties; (ii) metallurgical aspects and preparation techniques; (iii) magnetization process and magnetic hysteresis; (iv) energy losses and their dependence on the magnetizing frequency; (v) dependence of the magnetic properties on temperature and stress; (vi) mechanical properties; (vii) applications.

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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.

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