It is well known that the form of a piece of ferromagnetic metal is in general slightly changed by magnetization.
The property of being strongly attracted to either pole of a magnet. Ferromagnetic materials, such as iron, contain unpaired electrons, each with a small magnetic field of its own, that align readily with each other in response to an external magnetic field. This alignment tends to persists even after the magnetic field is removed, a phenomenon called hysteresis. Ferromagnetism is important in the design of electromagnets, transformers, and many other electrical and mechanical devices, and in analyzing the history of the earth's magnetic reversals. Compare diamagnetism, paramagnetism.
ferromagnetic adjective (fěr'ō-māg-nět'ĭk)