Curie–Weiss law

The Curie -Weiss law (after Pierre Curie and Pierre -Ernest Weiss ) describes the magnetic properties of paramagnetic substances in which cause magnetic cooperative effects for the deviation from the ideal Curie behavior. Such cooperative effects occur due to the exchange interaction, the direct interaction of magnetic dipole moments of neighboring paramagnetic atoms plays a subordinate role. By this influence, it is below the Curie temperature ferromagnetism.

The Curie- Weiss law shows the temperature dependence of magnetic susceptibility of a ferromagnet in the high temperature phase, ie above the Curie temperature

With the Curie constants.

The equation states that the magnetic susceptibility in the para phase diverges as it approaches the temperature of above the Curie temperature.

Analog with ferrimagnetic and antiferromagnetic systems

At ferrimagnetic and antiferromagnetic systems the magnetic susceptibility above its phase transition temperature, the Neel temperature can be described by a slightly altered formula:

In this case, " diverges " the susceptibility of the high-temperature phase apparently against a negative temperature.