Curie Temperature
Definition and meaning of Curie Temperature in chemistry.
Curie temperature is the critical temperature above which a ferromagnetic or ferrimagnetic material loses its spontaneous magnetization and becomes paramagnetic.
In more detail
Below this temperature, exchange interactions lock neighboring atomic magnetic moments into aligned domains, giving the material strong, persistent magnetism. As temperature rises, increasing thermal (lattice) vibration disrupts this alignment, and at the Curie temperature the ordered domain structure collapses entirely in a second-order phase transition. Above it, the material's magnetic susceptibility still responds weakly to an external field but follows the Curie-Weiss law, with susceptibility falling off as temperature increases further. The concept is essential for designing magnets, transformers, and magnetic storage media that must retain their properties across operating temperatures.
Key facts
| Field | Physical Chemistry |
|---|---|
| Named after | Pierre Curie (1895) |
| Iron (Fe) Curie temperature | ~770 °C (1043 K) |
| Nickel (Ni) Curie temperature | ~354 °C (627 K) |
Iron has a Curie temperature of about 770 degrees C (1043 K); heated past this point, a piece of iron stops behaving as a permanent magnet and becomes paramagnetic.
Frequently asked questions
What happens to a magnet above its Curie temperature?
It loses its spontaneous, permanent magnetization and becomes paramagnetic, meaning it can still be weakly magnetized by an external field but shows no magnetism once that field is removed.
Is the Curie temperature the same for every magnetic material?
No, it depends on the strength of the exchange interaction between atomic moments; for example iron, cobalt, and nickel each have distinct Curie temperatures.