Editing Curie temperature (section)

=== Ferromagnetic ===
{{main|Ferromagnetism}}

Materials are only ferromagnetic below their corresponding Curie temperatures. Ferromagnetic materials are magnetic in the absence of an applied magnetic field.

When a magnetic field is absent the material has [[spontaneous magnetization]] which is a result of the ordered magnetic moments; that is, for ferromagnetism, the atoms are symmetrical and aligned in the same direction creating a permanent magnetic field.

The magnetic interactions are held together by [[exchange interaction]]s; otherwise thermal disorder would overcome the weak interactions of magnetic moments. The exchange interaction has a zero probability of parallel electrons occupying the same point in time, implying a preferred parallel alignment in the material.<ref name=Hall1>{{harvnb|Hall|Hook|1994|pp=220–21}}</ref> The Boltzmann factor contributes heavily as it prefers interacting particles to be aligned in the same direction.<ref name=Palmer>{{harvnb|Palmer|2007|pp=}}</ref> This causes [[Ferromagnetism|ferromagnets]] to have strong magnetic fields and high Curie temperatures of around {{convert|1000|K|C}}.<ref name=Hall3>{{harvnb|Hall|Hook|1994|p=220}}</ref>

Below the Curie temperature, the atoms are aligned and parallel, causing spontaneous magnetism; the material is ferromagnetic. Above the Curie temperature the material is paramagnetic, as the atoms lose their ordered magnetic moments when the material undergoes a phase transition.<ref name=Cusack/>