Opposing sublattices explain more than one kind of magnet
Néel developed descriptions of antiferromagnetism and ferrimagnetism using coupled magnetic sublattices. Equal opposing moments can cancel in an antiferromagnet; unequal opposing sublattices can leave a net moment in a ferrimagnet.
His 1948 ferrimagnetic theory helped explain ferrites. The 1970 award recognized both antiferromagnetism and ferrimagnetism, rather than treating every magnetic material as a ferromagnet with a smaller signal.
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Temperature response reveals coupling
Susceptibility above an ordering temperature and the development of sublattice order below it constrain the interactions. A small total moment can hide large ordered sublattice moments. Compensation of the total moment need not mean the internal order has vanished.
Sources: [1]
Structure needs a spatial probe
Neutron diffraction can respond to ordered magnetic moments and their spatial arrangement. Together with susceptibility, it distinguishes candidate sublattice structures more sharply than a magnetization curve alone. A molecular-field model remains an approximation to correlations and fluctuations.
Spin order and spin transport are separate questions
The spin-chain Lab follows correlations in a finite model. The GMR Lab follows transport when two layer magnetizations change their relative angle. Neither is a direct reconstruction of a measured ferrite, and a resistance contrast alone does not establish its atomic magnetic structure.