Classification of Materials
Diamagnetic: P < 1, thus?? and ? are negative (and small)
Paramagnetic: P > 1, thus ? and ? are positive
Ferromagnetic: P >> 1, and large values of ? and ?
Antiferromagnetic: P > 1, ? and ? are positive (similar or smaller than for paramagnetic compounds)
Ferrimagnetic: Same as antiferromagnetic, but different ions involved so do not cancel out.