Antiferromagnetism

Antiferromagnetism is a type of magnetic ordering, just like ferromagnetism and ferrimagnetism. In antiferromagnets the individual magnetic dipoles are oriented in a way such that the bulk of the material has a vanishing total magnetization. In the simplest model, as shown in the picture on the right, neighboring moments in an ordered lattice are oriented antiparallel to one another. Since there are multiple ways of arranging magnetic moments on a lattice (especially in three dimensions), there exist various types of antiferromagnetic ordering. The phenomenon of antiferromagnetism was first introduced by Lev Landau in 1933.

Generally, antiferromagnetic order may exist at sufficiently low temperatures, but vanishes at and above the Néel temperature – named after Louis Néel, who had first identified this type of magnetic ordering. Above the Néel temperature, the material is typically paramagnetic.