M. I. Bichurin

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

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

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.

Magnetoelectric microwave phase shifter

An electric field tunable yttrium iron garnet (YIG)-lead zirconate titanate (PZT) phase shifter based on ferromagnetic resonance (FMR) is designed and characterized. The electric field control of the phase shift δφ arises through magnetoelectric interactions. The piezoelectric deformation in PZT in an electric field E leads to a shift in the FMR frequency in YIG and a phase shift. For E=5–8kV∕cm applied across PZT, δφ=90°–180° and an insertion loss of 1.5–4dB are obtained. Theoretical estimates of δφ are in excellent agreement with the data.

Theory of magnetoelectric effect for bending modes in magnetostrictive-piezoelectric bilayers

In a magnetostrictive-piezoelectric bilayer the interaction between the magnetic and electric subsystems occurs through mechanical deformation. A model is discussed here for the resonance enhancement of such magnetoelectric (ME) interactions at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The frequency dependence for longitudinal and transverse ME voltage coefficients have obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end. It is shown that the bending resonance and consequent enhancement in ME coupling occurs at the lowest frequency for a bilayer that is fixed at one end and free at the other end. The model is appli...

Magnetoelectric gyration effect in Tb1−xDyxFe2−y∕Pb(Zr,Ti)O3 laminated composites at the electromechanical resonance

A giant current-to-voltage (I-V) gyration effect was found in magnetostrictive Tb1−xDyxFe2−y and piezoelectric Pb(Zr,Ti)O3 laminated composites. An equivalent circuit theory was developed for magnetoelectric gyration, which predicted that I-V conversion is reduced by a frequency transfer function ZR(f) and that the maximum occurs at resonance. A giant conversion coefficient up to 2500V∕A was predicted and confirmed.

Present status of theoretical modeling the magnetoelectric effect in magnetostrictive-piezoelectric nanostructures. Part I: Low frequency and electromechanical resonance ranges

Mechanical deformations of a magnetostrictive-piezoelectric bilayer result in the interaction between the magnetic and electric subsystems. This review reports the models for describing the distinctive features of magnetoelectric (ME) interactions in ferrite-piezoelectric nanostructures at low-frequencies and in electromechanical resonance region. Expressions for ME coefficients are obtained using the solution of elastostatic/elastodynamic and electrostatic and magnetostatic equations. The ME voltage coefficients are estimated from known material parameters. The models take into account the clamping effect of substrate, flexural deformations, and the contribution of lattice mismatch between composite phases and substrate to ME coupling. Lattice mismatch effect has been taken into account by using the classical Landau–Ginsburg–Devonshire phenomenological thermodynamic theory. For a nickel ferrite-lead zirconate titanate nanobilayer on SrTiO3 substrates, the strength of low-frequency ME interactions is show...

Large magnetoelectric susceptibility: The fundamental property of piezoelectric and magnetostrictive laminated composites

The magnetoelectric (ME) susceptibility (αme) is the fundamental property that describes the coupling between the polarization and magnetization of a ME media. It is a complex quantity (αme*) which has rarely been studied. Here, we report investigations of the ME susceptibility for various ME laminated composites, which demonstrates that αme is on the order of 10−7s∕m for these materials, which is dramatically larger than that of single phase materials.

Giant magnetoelectric effect in composite materials in the region of electromechanical resonance

The magnetoelectric effect in multilayer ferrite-piezoelectric composites has been theoretically and experimentally studied. Using the method of effective parameters, an expression for the magnetoelectric coefficient is determined and its frequency dependence is analyzed. It is shown that, in the region of electromechanical resonance, the magnitude of the effect exceeds a low-frequency value by more than an order of magnitude. The results of calculations obtained for a nickel ferrite spinel-PZT composite are in good agreement with the experimental data.

A quasi(unidirectional) Tellegen gyrator

We show that magnetoelectric (ME) laminate composites have characteristics of a previously conjectured, but unfound, fifth network circuit element—the Tellegen gyrator. Our findings establish that ME laminate composites (i) are nonreciprocal electrical elements, (ii) have significant nondissipative I-V conversion near a resonance frequency, and (iii) act like a unidirectional gyrator, i.e., an ideal Tellegen gyrator connected with a capacitor on one side and an inductor on the other.

Modeling of Magnetoelectric Effect in Ferromagnetic/Piezoelectric Multilayer Composites

A theoretical model is presented for of magnetoelectric effect in bilayer and multilayer composites. A novel approach to take into account the actual boundary conditions in multilayer composites is proposed. An averaging method is used for deriving effective material parameters in composites. The effect of dielectric and magnetic parameters on the magnetoelectric susceptibility is studied. The estimated magnetoelectric coupling constants are compared with data for nickel ferrite and lead zirconate titanate composite.