Ferromagnetic Heat Capacity in an External Magnetic Field near the Critical Point

Some thermodynamic principles useful for understanding the heat capacity of a ferromagnet in an external field near its critical (Curie) point are discussed, with special emphasis on the influence of demagnetizing effects. Two simple examples show the variety of behavior which may be expected, depending on the magnitude of the external field. The utility of considering low-field and high-field limits is pointed out, with particular reference to Ni and EuS.