Is Curie-Weiss law valid in every ferro-to-para transition?

The Curie-Weiss law is obeyed where there is a change in the order parameter and the symmetry of molecules at the transition temperature (T-c) of ferro-to-para phase. The ferroelectric transition is not strictly governed by the Curie-Weiss law. In fact, a number of solid ferroelectrics show deviation from the Curie-Weiss law. It has been shown in the present letter that the de-Vries electroclinic liquid crystals, with a wide smectic A (Sm-A) phase and a high electroclinic effect, do not obey the Curie-Weiss law. The nonlayer shrinkage leads to symmetry conservation that makes the observance of soft mode impossible and hence the deviation. (c) 2005 American Institute of Physics.