Magnetic material
Before the advent of the electromagnet, the magnet is in the case of no external magnetic field and electric field can be persistent objects generating magnetic field. Only specific materials only this feature, but the majority of the material in an applied magnetic field, due to the applied magnetic field will produce a magnetic field, according to the type of material, the generated magnetic field causes the object is outside the magnetic field to attract or repel. Can be divided into the following categories:
The ferromagnetic and ferrous magnetic material is a magnetic material generally recognized, will be any one pole of a magnet to attract, and can feel its attractiveness. Only such substances can be applied magnetic field disappears remained its magnetization characteristic, and therefore can be used as a magnet. Like a refrigerator magnet magnetic because such material. Ferrous magnetic material ferrite and the first natural magnet magnetite and lodestone, magnetic and ferromagnetic material similar to, but slightly weaker magnetic. The difference of the magnetic force between the two is caused because of its microstructure.
Paramagnetic material, such as platinum, aluminum and oxygen, and other substances, will be weak magnet is a very attractive, but its attractiveness only tens of parts per million of a ferromagnetic material, so only with a precision instrument to measurement. The ferrofluid refers suspension many nanoscale size of the ferromagnetic powder, because they can not be magnetized. Sometimes regarded as a paramagnetic material.
Anti-magnetic material, such as carbon, copper, water and plastic-like substance will be any one pole of the magnet exclusion, the repulsive force is very weak. Most of the substances are anti-magnetic, its magnetic permeability is slightly smaller than the permeability of vacuum, the repulsive force is very small if the use of ships magnet. If you are using a powerful superconducting magnets, like lead weights and even mice because the magnetic levitation floating in the air. Superconductors will be affected by the exclusion of the magnetic field is strong anti-magnetic materials.
The magnetic properties of the material in addition to the several, such as spin glass, antiferromagnetic superparamagnetic.