Crossover and splitting of the heat capacity peak

The fine structure of the peak of heat capacity C(p), which arises at the crossover point upon changing an external parameter p, is considered theoretically. If the hybridization of the states does not occur in the neighborhood of this point, then C(p) has the form of a double Schottky peak. The structure of the C(p) peculiarity becomes more complicated in the presence of the off-diagonal matrix elements and strongly depends on the relationship between temperature and the magnitude of the interaction between the levels. The experimental study of the phenomenon can give information about the relatively weak interatomic interactions in solids or molecules, e.g. about weak exchange interaction in paramagnets with an anisotropy of the “easy plane” type.