A magnet is an object that produces its own permanent magnetic field without the application of a magnetic field. But most materials need to generate a magnetic field in response to an applied magnetic field - this phenomenon is called magnetic. We call this kind of material that can react to the magnetic field in some way as magnetic material.
According to the structure of the material, the overall magnetic behavior of the material can vary greatly. According to the magnetic properties of the material in the external magnetic field, it can be divided into diamagnetic material, paramagnetic material, ferromagnetic material, antiferromagnetic material and ferrimagnetic material. Several forms of magnetic behavior have been observed in different materials, including:
Ferromagnetic and ferrimagnetic materials are generally considered to be magnetic materials; they are attracted to a sufficiently strong attraction and can feel attractive. These materials are the only materials that can remain magnetized and become magnets; a common example is the traditional refrigerator magnets.
Paramagnetic materials, such as platinum, aluminum, and oxygen, are weakly attracted to either pole of the magnet. This attraction is several hundred thousand times weaker than ferromagnetic materials, so it can only be detected by using sensitive instruments or using very powerful magnets.
Antimagnetism means being repelled by two poles. Carbon, copper, water and plastics are easily rejected by magnets. The permeability of the diamagnetic material is less than the vacuum permeability. Although the force applied to a magnetic object by ordinary magnets is too weak, when extremely powerful superconducting magnets are used, diamagnetic objects (such as lead blocks and even mice ) can be suspended so that they float in midair.
There are various other types of magnetism, such as rotating glass, superparamagnetism, supermagnetic heterogeneity, and supermagnetism.