Magnetic materials are widely used materials in production, life, defense science and technology. Such as the manufacture of various electric motors, transformers, various magnetic components in electronic technology and microwave tubes, filters and sensitizers in communications technology, magnetic mines in defense technology, electromagnetic guns, various household appliances, etc. . In addition, magnetic materials have also been widely used in geological exploration, marine exploration, and new technologies in information, energy, biology, and space. Magnetic materials are widely used. It is mainly to use its various magnetic properties and special effects to make components or devices; to store, transmit and convert electromagnetic energy and information, or to generate a magnetic field of a certain intensity and distribution in a specific space; sometimes directly in the natural form of the material. Use (such as magnetic fluid). Magnetic materials play an important role in the field of electronic technology and other science and technology.