A PSEUDO-2-DIMENSIONAL ISING-MODEL OF FERROELECTRICS

In this paper we consider an Ising bilayer as a chain of simple ladder s, characterized by intra-ladder and inter-ladder couplings, to study in detail the para- and ferroelectric behaviours (also considering the electrostrictive corrections in the intra-ladder direction of the pla ne) for different ratios of interaction constants and different values of electric field, by using a transfer matrix method for the intra-la dder interactions and the MF approximation for the inter-ladder intera ctions. In the particular case in which the interaction between two la yers (planes) is taken to be zero, our results reproduce entirely thos e obtained previously for a pseudo-one-dimensional Ising model, which explains the experimental data well for the thermodynamic properties o f 1D ferroelectrics such as CsD2PO4 (d-CDP).