Antiferromagnetism

When no external field is applied, the antiferromagnetic structure corresponds to a vanishing total magnetization.

[citation needed][3] The magnetic susceptibility of an antiferromagnetic material typically shows a maximum at the Néel temperature.

Various microscopic (exchange) interactions between the magnetic moments or spins may lead to antiferromagnetic structures.

Geometrical frustration or competing ferro- and antiferromagnetic interactions may lead to different and, perhaps, more complicated magnetic structures.

This fact is due to the contribution of the hysteresis loop,[4] which for ferromagnetic materials involves a residual magnetization.

The experiments, performed by Clifford Shull, gave the first results showing that magnetic dipoles could be oriented in an antiferromagnetic structure.

This provides the ability to "pin" the orientation of a ferromagnetic film, which provides one of the main uses in so-called spin valves, which are the basis of magnetic sensors including modern hard disk drive read heads.

Unlike ferromagnetism, anti-ferromagnetic interactions can lead to multiple optimal states (ground states—states of minimal energy).