ON THE MAGNETIC 3-SUBLATTICE MODEL WITH 2 EQUIVALENT SUBLATTICES

The magnetic 3-sublattice model is analysed for the case that the 3 su blattices are coupled by a Heisenberg type of exchange interaction, an d 2 of the 3 sublattices are equivalent and coupled by equal exchange parameters with the third sublattice. The possible magnetic configurat ions of the 3-sublattice system in a magnetic field are derived, and a classification is given of the combinations of sublattice magnetizati ons and exchange parameters according to the type of zero-temperature magnetization curve to which the combination corresponds. Finally it i s proved that all phase transitions are of second-order type.