K.P. Belov Lomonosov Moscow State University, Department of Physics, Leninskie Gory 1 build. 2, Moscow, 119991, Russian Federation
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’ TB 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 TB is nothing else but the low-temperature transformation point Tt(100-120 K).