LAUSR

Abstract Ferroelectric Liquid crystals (FLCs) are increasingly used not only in displays but also in the preparation of new materials with unconventional properties. Among these FLC-based materials, magnetoelectric FLCs are of significant interest, due both to their fundamental properties as well as their many applications in the industry. This is primarily because their electric and magnetic properties can be varied by applying external fields. Magnetoelectric FLCs, as a mixture of magnetic nanoparticles and FLCs, exhibit ferroelectricity and ferromagnetism simultaneously, and hence, offer promising benefits for many applications in the industry. We present a theoretical study of the magnetic behavior of these new soft magnetoelectric materials, under time-varying external fields. We have obtained the complex permeability of the system as a function of temperature and the frequency of applied fields, in the vicinity of Isotropic-Smectic C* (I-SmC*) transition point. We have performed the calculations based on the phenomenological Landau theory and a modified form of free energy. The results show the first order characteristics of I-SmC* phase transition of a magnetic FLC nanosuspension. It is also shown that the magnetic permeability will decrease with increasing frequency of the field. We have also investigated the effect of magnetic nanoparticle concentrations on the FLC's magnetic permeability. Our results show that increasing the nanoparticle concentrations will lead to increased permeability, as long as the nanoparticles are small enough not to disturb the ordering of layer spacing, and as long as the strength of the applied field is lower than the unwinding critical field.