Theory of low-frequency magnetoelectric effects in ferromagnetic-ferroelectric layered composites

Abstract

A theoretical model is presented for low-frequency magnetoelectric (ME) effects in bilayers of magnetostrictive and piezoelectric phases. An approach is proposed for the consideration of actual boundary conditions at the interface. An averaging method is used to estimate effective material parameters. The model predicts the strongest ME effect in cobalt ferrite-lead zirconate titanate (PZT) among ferrite based composites. The ME voltage coefficient for transverse field orientation is estimated to be 25–50% higher than for the longitudinal case. Comparison with data for multilayer samples reveals poor interface coupling in cobalt ferrite-PZT and ideal coupling in nickel ferrite-PZT.

Dynamic magnetoelectric effects in bulk and layered composites of cobalt zinc ferrite and lead zirconate titanate

“…The ME voltage coefficients are directly proportional to the product of pseudopiezomagnetic coupling q=δλ/δH, where λ is the magnetostriction, and the piezoelectric coefficient d. The H-dependence in Fig.2 essentially follows the slope of λ vs H. When λ attains saturation, the loss of piezomagnetic coupling leads to the absence of ME effect. Other features in Fig.2, such as zerocrossing and sign reversal, are due to competing qd terms and their variation with H [8][9][10].…”

“…We introduced a coupling parameter k to describe the interface coupling, with k=1 for an ideal interface and k=0 for a frictionless case [9,10]. An averaging method was used to obtain the following expressions for the ME voltage coefficients: [4,13,15].…”

“…The coupling weakens for higher Zn substitution. These data have been analyzed using our recent model for a bilayer of ferrite-PZT [9,10]. A unique feature in the model is the introduction of an interface coupling parameter k, with k=1 for an ideal interface and k=0 for the frictionless case.…”

Ultrahigh magnetic field sensitivity in laminates of TERFENOL-D and Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals

“…Our configuration is significantly different than previous reports. [5][6][7][8][9][10][11][12][13][14][15]17 In our L -T laminate, because the piezomagnetic and piezoelectric layers are mutually coupled via strain S(z) and stress T(z), application of H along the length axis of the magnetostrictive layer puts the piezoelectric one into forced oscillation along this direction. A voltage is generated across the thickness or transverse direction of the piezoelectric layer, via the transverse piezoelectric constant d 31,p .…”

“…Prior analysis of magnetoestrictive/piezoelectric laminates has simply combined the magnetostrictive and piezoelectric constitutive equations. 7,9,12,[15][16][17] This is inadequate to understand energy coupling between layers under dynamic drive. In our analysis, we used an equation of motion to couple the two constitutive equations.…”