Ferrimagnets with a 'weak' magnetic sublattice

Measurements on the anomalous temperature behaviour of the spontaneous magnetisation in various ferrimagnets (N-, M-, and P-type Neel curves) are analysed and summarised. The concept of a 'weak' magnetic sublattice is applied to explain the anomalies as well as manifestations of the 'low-temperature point' T_B and the antiferromagnetic-type paraprocess. The paraprocess phenomenon causes sign anomalies in the magnetocaloric effect, magnetostriction, and the 'first' component of the isotropic magnetoresistance. It is suggested that in magnetite (Fe₃O₄) the role of a 'weak' sublattice is played by the spin-ordered subsystem of hopping electrons ('magnetoelectron' sublattice), and the appearing point T_B is nothing else but the low-temperature transformation point T_t(100-120 K).