Theory of low frequency magnetoelectric coupling in magnetostrictive-piezoelectric bilayers

TL;DR

This paper develops a theoretical model for low-frequency magnetoelectric effects in magnetostrictive-piezoelectric bilayers, introducing an interface coupling parameter and analyzing different boundary conditions and field orientations.

Contribution

A novel theoretical framework incorporating an interface coupling parameter to predict magnetoelectric effects in bilayers with various boundary conditions and field orientations.

Findings

Predicted giant ME coupling in specific bilayer combinations.

Derived expressions for ME voltage coefficients under different conditions.

Analyzed effects of boundary conditions and field orientations on ME coupling.

Abstract

A theoretical model is presented for low-frequency magnetoelectric (ME) effects in bilayers of magnetostrictive and piezoelectric phases. A novel approach, the introduction of an interface coupling parameter k, is proposed for the consideration of actual boundary conditions at the interface. An averaging method is used to estimate effective material parameters. Expressions for ME voltage coefficients are obtained by solving elastostatic and electrostatic equations. We consider both unclamped and rigidly clamped bilayers and three different field orientations of importance: (i) longitudinal fields in which the poling field, bias field and ac fields are all parallel to each other and perpendicular to the sample plane; (ii) transverse fields for magnetic fields parallel to each other and perpendicular to electric fields, and (iii) in-plane longitudinal fields for all the fields parallel to each other and to the sample plane. The theory predicts a giant ME coupling for bilayers with cobalt ferrite (CFO), nickel ferrite (NFO), or lanthanum strontium manganite (LSMO) for the magnetostrictive phase and barium titanate (BTO) or lead zirconate titanate (PZT) for the piezoelectric phase.