The permanent magnet can be a natural product, also known as a natural magnet, or it can be made by hand (the strongest magnet is a neodymium iron boron magnet).
When a non-permanent magnet is heated to a certain temperature, it will suddenly lose its magnetic properties. This is because the arrangement of many "meta-magnets" that make up the magnet is caused by order to disorder; the magnet that loses magnetism is placed in the magnetic field when the magnetization is When a certain value is reached, it is magnetized again, and the arrangement of "meta magnets" is from disorder to order. Basic Greeks and Chinese found that there is a natural magnetized stone in nature, called "the magnet." This stone can magically pick up small pieces of iron and always point in the same direction after swinging at will. Early voyagers used this magnet as their earliest compass to discern the direction at sea.
After thousands of years of development, today's magnets have become a powerful material in our lives. The same effect as the magnetite can be achieved by synthesizing alloys of different materials, and the magnetic force can also be increased. Man-made magnets appeared in the 18th century, but the process of making stronger magnetic materials was very slow until the 1920s when Alnico was made. Subsequently, Ferrite was fabricated in the 1950s, and rare earth magnets were produced in the 1970s [Rare Earth magnets including NdFeB and SmCo). At this point, magnetic technology has developed rapidly, and magnetic materials have also made components more compact.