Anti ferromagnetic materials such as chromium have a small but positive susceptibility. They cannot possess any magnetization is the absence of an applied field, in contrast to ferromagnetism. Ant ferromagnetic materials possess a magnetic ordering. In that ordering, the magnetic moments of alternating atoms in the crystals align in opposite directions as depicted in this.

The opposite alignments of atomic magnetic moments are due to quantum mechanical exchanges forces. The net result is that in the absence of an applied field. Ant ferromagnetism occurs, below a critical temperature called the Neel temperature. Above these materials becomes paramagnetic.