commonly referred to as magnetic materials, are ferromagnetic materials and are ancient and widely used functional materials. Modern magnetic materials have been widely used in our lives, such as the use of permanent magnet materials as motors, core materials for use in transformers, magneto-optical disks used as memories, magnetic recording floppy disks for computers, and the like. According to Big Bit, magnetic materials are closely related to all aspects of information technology, automation, mechatronics, national defense, and the national economy. It is generally considered that a magnetic material refers to a substance which can directly or indirectly generate magnetism by a transition element such as iron, cobalt, nickel, or an alloy thereof. Magnetic materials can be classified into soft magnetic materials and hard magnetic materials according to the difficulty of demagnetization after magnetization. A substance that is easy to remove magnetism after magnetization is called a soft magnetic material, and a substance that is not easily demagnetized is called a hard magnetic material. Generally speaking, the soft magnetic material has a small residual magnetization, and the hard magnetic material has a large residual magnetism.
Experiments have shown that any substance can be magnetized more or less in an external magnetic field, except that the degree of magnetization is different. According to the characteristics of substances in the external magnetic field, substances can be divided into five categories: paramagnetic substances, diamagnetic substances, ferromagnetic substances, submagnetic substances, diamagnetic substances.
According to the molecular current hypothesis, substances should exhibit substantially similar characteristics in magnetic fields, but here we are told that the properties of substances in external magnetic fields vary widely. This reflects the limitations of the molecular current hypothesis. In fact, the microstructure of various substances is different, and the difference in the structure of this substance is the cause of the difference in the magnetic properties of matter.
We refer to paramagnetic and diamagnetic materials as weak magnetic materials and ferromagnetic materials as ferromagnetic substances.
The so-called magnetic material refers to a ferromagnetic substance. Magnetic materials can be classified into soft magnetic materials and hard magnetic materials according to the difficulty of demagnetization after magnetization. A substance that is easy to remove magnetism after magnetization is called a soft magnetic material, and a substance that is not easily demagnetized is called a hard magnetic material. Generally speaking, the soft magnetic material has a small residual magnetization, and the hard magnetic material has a large residual magnetism.
