Specific heat study of ferroelectric CsH2PO4and CsD2PO4

Abstract
For ferroelectric CsH2PO4 and CsD2PO4 the specific heat has been measured using an AC calorimeter. The singularity of the specific heat at the phase transition point is logarithmic. The most characteristic feature of the behaviour is the existence of an anomalous specific heat over the wide temperature region from Tc-60K to Tc+60K. This anomalous specific heat is considered to be due to the one-dimensional fluctuation of the polarisation in these materials. The authors also compare the experimental results with the pseudo-one-dimensional Ising model.