Permanent magnet permanent magnet can be a natural product, also known as natural magnet, can also be made by hand (the strongest magnet is NdFeB magnet.) With a wide hysteresis loop, high coercivity, high remanence, once the magnetization That is, a material that maintains a constant magnetism. Also known as permanent magnetic materials, hard magnetic materials. In the application, the permanent magnet works on the second quadrant demagnetization part of the magnetic saturation loop and the magnetization return line after magnetization. Permanent magnet should have the highest possible coercivity Hc, remanence Br and maximum energy product (BH) m, in order to ensure maximum storage of magnetic energy and stable magnetic.