Ferroelectrics and multiferroics

I. Magnetoelectric effect of mildly conducting magnetostrictive/piezoelectric particulate composites

A relatively simple model has been developed to study the magnetoelectric effect of magnetostrictive/piezoelectric dilute particulate composites. For illustrative purpose, we calculate the magnetoelectric voltage coefficients of particulate composites of NiFe2O4 and lead zirconate titanate. By treating the inclusion/matrix as mildly conducting materials, we have reproduced all the key experimental features of magnetoelectric behavior of the particulate composites. In addition, the qualitative dependence of the calculated magnetoelectric voltage coefficients on the constituent’s electrical conductivity is also in good agreement with recent experimental observations.

Research output: J. Appl. Phys., 100, 043910, 2006

II. Electrical conductivity enhanced dielectric and ferroelectric properties of interface-coupled ferroelectric superlattices

We have developed a model to theoretically study the interplay of the effects of interfacial coupling and electrical conductivity on the ferroelectric and dielectric properties of superlattices consisting of alternating ferroelectric and paraelectric layers based on the Landau-Ginzburg theory. The qualitative predictions of the model are compared with recent experimental results for “symmetric” and “asymmetric” superlattices. It is shown that the consideration of time-dependent space-charge-limited conductivity and “interface structure” can satisfactorily account for the enhancement of the overall ferroelectric and dielectric properties of ferroelectric-paraelectric superlattices.

Research output: J. Appl. Phys., 100, 024101, 2006