A permanent magnet, or hard magnet, is a term used for objects made of a material that exhibits a wide magnetic hysteresis loop. This means that after applying a sufficient magnetic field to magnetize it, the atomic regions called magnetic domains will become aligned, and these ordered structures will not change after removing the field. This makes the material permanently magnetic, and its specific structure enables this. Characteristic features of a permanent magnet include the coercive force HcJ, which should be at least 24 kA/m. The greater the coercive force value, the higher the magnet's resistance to demagnetization by an opposing magnetic field, as in the case of motors and other electrical machinery and devices, as well as resistance to thermal demagnetization, which can occur at high or very high temperatures.
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