Surface effects and size effects on ferroelectrics with a first-order phase transition

Abstract

For ferroelectrics with a first-order phase transition, the contribution of surface to the free-energy expression was examined using transverse Ising model with four-spin interactions taken into consideration. It was shown that a $P^4$ term should be added to the surface term in the free-energy expression. The surface and size effect on polarization and Curie temperature was studied using the newly developed free-energy expression. Experimental results in the literature were successfully explained using the free-energy expression.