The development of extremely strong magnetic properties in certain materials which occurs when magnetic domains (regions at most 1 mm in dimension) become aligned in the absence of an applied field, below a temperature known as the Curie temperature. The net magnetization depends on the magnetic history (the hysteresis effect). Above the Curie temperature, these materials become paramagnetic. Iron, nickel, cobalt, and gadolinium are ferromagnetic at room temperature. Ferromagnetism is believed to be caused by magnetic fields generated by the electrons' spins in combination with a mechanism known as exchange coupling, which aligns all the spins in each magnetic domain.

Barkhausen Effect, Curie Temperature, Exchange Coupling, Ferroelectricity, Hysteresis Effect, Magnetic Domain, Magnetization, Paramagnetism