Magnet
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Exchange spring magnet
The magnetic moment of a bulk material is the sum of all of its atomic moments. The atomic moments' interactions with each other and with the externally applied field determine the behavior of the magnet. Each atomic magnetic moment tries to orient itself so that the total magnetic energy reaches a minimum. There are generally four types of energy competing with each other to reach equilibrium: each is derived from the exchange coupling effect, magnetic anisotropy, the magnetiostatic energy of the magnet, and the magnet's interaction with external field.