A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. These materials are called ferromagnetic or ferrimagnetic . They include the elements iron, nickel, and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone .
Permanent magnets are made from hard ferromagnetic materials such as Alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize .
Unlike electromagnets, permanent magnets produce a persistent magnetic field without the need for any external source of magnetism or electrical power .
There are five families of magnetic materials that you can choose from. These are, in order of increasing magnetic strength, the Flexible, Ceramic, Alnico, Samarium Cobalt, and Neodymium types . The information below summarizes the properties of each type to help you decide what you might need:
| Magnet Type | Magnetic Strength | Curie Temperature | Max Operating Temperature | Corrosion Resistance | Cost |
| Flexible | Low | 858°F (458°C) | 392°F (200°C) | Poor | Low |
| Ceramic | Low | 842°F (450°C) | 392°F (200°C) | Good | Low |
| Alnico | Medium | 1472°F (800°C) | 1022°F (550°C) | Good | High |
| Samarium Cobalt | High | 896°F (480°C) | 572°F (300°C) | Good | High |
| Neodymium | Very High | 590°F (310°C) | 302°F (150°C) | Poor | High |