Percolation Model of Magnetoelectric Effects in Ferrite/Piezoelectric Bulk Composite

A bulk composite consisting of ferrite-ferroelectric phases shows magnetoelectric (ME) effects that are product properties of the magnetostrictive deformation and piezoelectric charge generation$. $Bulk composites with strong ME effects are desirable over layered samples due to superior mechanical strength. Here we discuss a percolation approach for modeling the ME effect in bulk composite [1]. We calculated percolation threshold corresponding to structural phase transition of bulk composites from the state with ME interactions to a state with no ME interactions.Expressions for longitudinal and transverse low-frequency ME voltage coefficients have been obtained. Volume fractions corresponding to peak ME voltage coefficients are given. We obtained a piezoelectric volume fraction of 0.45 for maximum ME effect in bulk samples of lead zirconate titanate and nickel-cobalt ferrite. These estimates are in excellent agreement with data. supported by a grant from the NSF. \newline \newline [1] V. M. Petrov, M. I. Bichurin, V. M. Laletin, N. Paddubnaya, and G. Srinivasan, \textit{Magnetoelectric Interaction Phenomena in Crystals-NATO Science Series II. Vol. 164}, Eds. M. Fiebig, V. V. Eremenko, and I. E. Chupis (Kluwer Academic Publishers, London, 2004), p.65-70.