Magnetization reversal in weak ferrimagnets and canted antiferromagnets

In some ferrimagnets the total magnetization vanishes at a certain compensation temperature T*. In weak magnetic fields, the magnetization can change sign at T* (the magnetization reversal). Much rarer is observation of ferrimagnetic-like response in canted antiferromagnets, where the weak ferromagnetic moment is due to the tilting of the sublattice magnetizations. The latter phenomenon was observed in nickel (II) formate dihydrate Ni(HCOO)₂·2H₂O. The observed weak magnetic moment increases initially below T_N = 15.5K, equals zero at T* = 8.5K and increases again at lowering temperature. The sign of the low-field magnetization at any given temperature is determined by the sample's magnetic prehistory and the signs are opposite to each other at T < T* and T* < T < T_N.