On the theory of magnetic phase transitions. II: “Quasi phase transitions” the magnetic structure of vivianite

Abstract

The problem of appearance of peaks in the temperature dependence of the specific heat is examined on the basis of Landau's theory of second-order phase transitions. It is pointed out that not only real phase transitions but also called- “quasi phase transitions” cause peaks in the specific heat. The magnetic structure of vivianite is investigated, because it is possible that vivianite undergoes a “quasi phase transition”.