When an ionic compound exhibits two sub-atomic lattices with equal magnetic moments, the material is said to be .

When an ionic compound exhibits two sub-atomic lattices with equal magnetic moments, the material is said to be antiferromagnetic

Explanation:

Antiferromagnetism is a type of magnetism in solids such as certain metals and alloys as well as some ionic solids, whereby the magnetic domains or moments of the materials ( atoms, molecules, ions) are aligned in opposite directions.

The magnetic domain or moment of a material is the region in which the magnetic fields of atoms are grouped together and aligned.

In antiferromagnetism, the magnetism from magnetic atoms or ions oriented in one direction are cancelled by magnetism of other magnetic atoms or ions aligned in the opposite direction. The magnetic moments are equal in magnitude but oppositely directed. In ionic compounds, two sublattices of identical ons have opposite spin directions. Thus, the net magnetic moment of an antiferromagnet is zero.

Heating the solids disrupts this antiparallel arrangement of atomic moments of the magnets, and above a certain temperature called the Néel temperature, the arrangement disappears completely.