Magnetic materials are mainly composed of transition elements iron, cobalt, nickel and their alloys, which can produce magnetism directly or indirectly. Generally, magnetic materials refer to strong magnetic materials, which are ancient and widely used functional materials. The magnetism of materials was recognized and applied as early as 3000 years ago. For example, natural magnets were used as compass in ancient China. Modern magnetic materials have been widely used in our life, such as permanent magnetic materials used as motors, iron core materials used in transformers, magneto-optical discs used as memory, magnetic recording floppy disks for computers, etc. Magnetic materials are closely related to all aspects of informatization, automation, mechatronics, national defense and national economy. The importance of magnetic materials is self-evident.
Magnetic materials can be divided into soft magnetic materials and hard magnetic materials. The material that is easy to remove magnetism after magnetization is called soft magnetic material, and the material that is not easy to demagnetize is called hard magnetic material. Generally speaking, the remanence of soft magnetic materials is small and that of hard magnetic materials is large. The soft magnet comprises a silicon steel sheet and a soft magnet core; Hard magnets include alnico, SmCo, ferrite and NdFeB. Among them, the most expensive is SmCo magnets, the cheapest is ferrite magnet, and the highest performance is NdFeB magnets. However, the most stable performance and the best temperature coefficient is alnico magnet. Users can choose different permanent magnet according to different needs.
Magnetic materials can be divided into "metal and alloy magnetic materials" and "ferrite magnetic materials". Ferrite magnetic materials can be divided into polycrystalline structure and single crystal structure materials.
Magnetic materials are divided into: soft magnetic materials, permanent magnetic materials, magnetic recording moment magnetic materials, rotating magnetic materials and so on. There are both metal materials and ferrite materials in soft magnetic materials, permanent magnetic materials and magnetic recording moment magnetic materials; The rotating magnetic materials and high-frequency soft magnetic materials can only be ferrite materials, because the metal will produce huge eddy current effect at high frequency and microwave frequency, resulting in the unavailability of metal magnetic materials, while the resistivity of ferrite is very high, which will effectively overcome this problem and be widely used.
Magnetic materials include powder materials, liquid materials, block materials, film materials, etc.
English 
