Anomaly of the Specific Heat of Potassium Dihydrogen Phosphate at the Upper Curie Point

Abstract

THE dielectric properties of Rochelle salt, potassium dihydrogen phosphate and potassium dihydrogen arsenate, depend on the electric field in the same way that the properties of ferromagnetic substances depend on the magnetic field. The spontaneous polarization is large between the two Curie points and depends on temperature. Approaching the higher (normal) Curie point from lower temperatures, the spontaneous polarization vanishes. As a consequence the specific heat shows an anomaly, corresponding to the magneto-caloric effect in ferromagnetics.