Resonant Magnetoelectric Response Research Articles

Nonlinear Stress dependent Resonant Studies on Press-fit ME Composites

Considering the wide applications of magnetoelectric (ME) composites in sensors, actuators, and microelectronic devices, optimizing them for the maximum ME coupling response has recently sought great attention among researchers. The coupling response of ME composites is maximum when operated in resonance conditions. In this article, a two-dimensional coupled in-plane formulation is proposed based on the in-plane vibrational theory to capture the resonant ME response of Press-fit ME composites. The study is extended to analyze the effect of stress and temperature on the resonant ME response of press-fit ME composites. The proposed theoretical formulation is validated experimentally and found to agree with each other. The numerical analysis is performed using the commercially available finite element software COMSOL® utilizing the Frequency Domain Perturbation study steps. The study reveals a nonlinear decrement in the peak resonant ME response with respect to both externally applied pre-stress and temperature conditions.

Modeling of resonant magnetoelectric response in press-fit embedded ring composite

Magnetoelectric (ME) effect is a product property arising out of the interactions between the piezoelectric and the magnetostrictive phase. Multi-phase ME composites being multifunctional materials find use in myriad of applications. In this work, epoxy free two phase and three phase embedded ring ME composites have been fabricated by the press-fit technique. For a comparative study, three phase conventional epoxy bonded ring shaped composite of same dimensions have also been fabricated. Dynamic ME experiment has been conducted at room and elevated temperatures on all the prepared composites. It is shown that the epoxy free composite by virtue of the absence of epoxy shows a better resonant ME response at all temperatures. The significance of the Electromechanical Resonance (EMR) in the resonance behavior of the composites has also been highlighted. An analytical model in cylindrical coordinate system incorporating the temperature effects on the individual composite constituents and their interface coupling has been developed based on the concentric ring approach to predict the dynamic ME behavior of the epoxy free ring composite at different temperatures. The model has been further used to study the effect of volume fraction of the constituents on the ME response.

Effects of Flexoelectricity and Surface Elasticity on the Nonlinear Magnetoelectric Coupling in Unsymmetric Composites

Flexoelectricity is the development of an electric field under an applied strain gradient. This effect is highly size-dependent and is significant at nanoscales. Unsymmetric magnetoelectric (ME) composites undergo bending deformations under a magnetic field that results in non-zero strain gradients. Hence, it is important to give due consideration to flexoelectricity, along with direct piezoelectricity in these composites. This article presents a finite-element model that predicts the static and dynamic behavior of ME nanobeams subjected to magnetic fields. The effect of material nonlinearity of the ferromagnetic phase and flexoelectricity in the ferroelectric phase on the ME coupling are determined, and the obtained results show agreement with the literature. It is found that flexoelectricity results in substantially higher static ME coefficients. However, the resonant ME response is weakened by flexoelectricity. The effect of surface elasticity on the ME coupling coefficient is also investigated by making use of the Gurtin–Murdoch theory. The surface effects are found to improve the ME coefficient at bending resonance, while its effect is trivial at static and axial resonant conditions. Furthermore, the effect of load resistance on the ME voltage and charge coefficients is determined. The results indicate clear changes in the trend between short-circuit and open-circuit conditions.

Effect of excitation mode on the magnetic field detection limit of magnetoelectric composite cantilevers

Magnetic field excitation of strain-coupled magnetoelectric composite cantilevers in different bending modes is investigated for magnetic field sensing, yielding the sensitivity, noise, and magnetic field detection limit. An analytic theory covering the resonant magnetoelectric response and thermal vibration noise of arbitrary bending modes and the Johnson–Nyquist noise from the composite and electronics is presented, and detection limit results of thin film FeCoBSi–Si–AlN composite cantilevers are calculated for the first three bound–free and free–free bending modes over a wide range of dimensions. We use size-scaling to yield the same 1 kHz resonance frequency for all modes and dimensions, constant quality factors Qf = 1000, and thickness-independent experimental material parameters. Magnetic field detection limits in the 1 pT/Hz1/2 to 100 fT/Hz1/2 range are predicted for practical cantilever dimensions, whereby higher modes are found to yield lower detection limits at similar functional layer thicknesses but a greater cantilever size. All detection limits are found to be thermal vibration noise limited and for different modes to display the same 1/size2 scaling behavior but require different FeCoBSi–Si–AlN layer thickness ratios.

Study on axial resonance magneto-electric (ME) effects of layered magneto-electric composites

An experimental investigation has been carried out to capture the magneto-mechanical behavior and material parameters of magnetostrictive material. Further, the experimental study is extended to capture the magnetoelectric (ME) coupling response of trilayered composites by applying both alternating and static magnetic fields. From the experiments, it is observed that the magnetostrictive material has a nonlinear hysteretic behavior. Hence, a three dimensional (3-D) nonlinear constitutive model has been proposed based on a thermodynamic framework and multisurface plasticity. In ME composites, it is also observed that a large ME coupling response can be obtained while operating near resonance frequencies. To capture the resonant ME effects, a theoretical formulation has been proposed based on axial vibrations theory and the proposed constitutive model has been incorporated in the formulation. The simulated resonant ME coupling response based on the proposed formulation is compared with the experimental data and found to be in agreement with each other. Further, a parametric study has been performed to address the variation of the resonant ME response as a function of various parameters such as axial compliance ratio, volume fraction of constituents, temperature, direction of magnetic loading and aspect ratio. This study reveals that the coupling response can be optimized by choosing the suitable parameters based on design requirement.

Resonant magnetoelectric response of composite cantilevers: Theory of short vs. open circuit operation and layer sequence effects

The magnetoelectric effect in layered composite cantilevers consisting of strain coupled layers of magnetostrictive (MS), piezoelectric (PE), and substrate materials is investigated for magnetic field excitation at bending resonance. Analytic theories are derived for the transverse magnetoelectric (ME) response in short and open circuit operation for three different layer sequences and results presented and discussed for the FeCoBSi-AlN-Si and the FeCoBSi-PZT-Si composite systems. Response optimized PE-MS layer thickness ratios are found to greatly change with operation mode shifting from near equal MS and PE layer thicknesses in the open circuit mode to near vanishing PE layer thicknesses in short circuit operation for all layer sequences. In addition the substrate layer thickness is found to differently affect the open and short circuit ME response producing shifts and reversal between ME response maxima depending on layer sequence. The observed rich ME response behavior for different layer thicknesses, sequences, operating modes, and PE materials can be explained by common neutral plane effects and different elastic compliance effects in short and open circuit operation.

Magnetoelectric coupling in nonidentical plasmonic nanoparticles: Theory and applications

We explore the optical properties of a meta-atom made of plasmonic nanopatches that possess an increasing degree of complexity. We show that if two nanopatches are strongly coupled and have a different geometrical footprint, the meta-atom exhibits a resonant magnetoelectric response, in addition to the anticipated resonant electric and magnetic response. Thus, it behaves similarly as the so-called omega particle, but with the unique advantage that frequency and strength of this magnetoelectric resonance can be independently tuned and modified with respect to the corresponding values of the electric resonance. This allows a metasurface of such meta-atoms to possess widely controlled reflection and transmission coefficients, e.g., the regimes of strongly asymmetric reflectance and perfect absorption become possible. Alternatively, an individual meta-atom of such kind can act as a directive nanoantenna with zero backscattered fields (Huygens' scatterer).

Theoretical investigation of magnetoelectric effect in multilayer magnetoelectric composites

The aim of this paper is the modeling of an arbitrary magneto–elasto-electric multilayer constitute by magnetostrictive, piezoelectric and elastic substrate layers under free–free boundary conditions. A dynamic theory corresponding to the driving frequency of magnetoelectric (ME) response coupled flexural and extensional oscillations was constructed. In the proposed model, the influence of thickness dependence of stress, strain and magnetic, electric fields within a sample stack are taken into account. The results of ME voltage coefficient dependent on driving frequency are obtained based on magnetostrictive, piezoelectric and elastic constitutive equations. As a demonstration, the numerical results are given for the Terfenol-D/PZT/Si material system with magnetic field excitation parallel and electric polarization perpendicular to the multilayer, which constituted by bilayer Terfenol-D/PZT placed on a Si elastic substrate. The theoretical model for static ME response in such structures is also established. Based on the model, some calculations on ME response are conducted and discussed. Our results show that in both the static and resonant ME response, the dimensional parameters of the layer sequence, piezoelectric fraction and substrate thickness essentially determined the ME voltage coefficient. Furthermore, the influences of load impedance on the magnetoelectric coupling coefficients are also investigated.

Resonant magnetoelectric response of cantilevers with magnetostrictive and piezoelectric layers on opposite sides of the substrate

A theory is derived for the bending-mode magnetoelectric coefficients at resonance for magnetostrictive and piezoelectric layers on opposite sides of a substrate. Results are given for the transverse ME coefficient in the Metglas-Si-AlN system with magnetic field excitation parallel and electric polarization perpendicular to the cantilever. The center-substrate layer sequence is found to produce about 50 % enhancement of the magnetoelectric effect compared to magnetoelectric bilayers on one side of a substrate. Up to about 10 % additional enhancement of the ME effect is predicted if the magnetostrictive and piezoelectric layers are separated from the substrate by spacer layers with lower Youngs modulus. Lowest order bending mode resonance frequencies are given.

Highly zero-biased magnetoelectric response in magnetostrictive/piezoelectric composite

The magnetoelectric (ME) coupling is investigated in laminated composites employing piezoelectric ceramic PZT (PZT-8), iron-nickel-based ferromagnetic alloy with constant elasticity (FeNi-FACE), and soft magnetic amorphous ribbon FeCuNbSiB (Fe73.5Cu1Nb3Si13.5B9). The two different ferromagnetic materials of FeNi-FACE and FeCuNbSiB result in built-in dc magnetic bias (Hdc) due to difference in their magnetic permeability and coercivity. In addition, the relatively high mechanical quality factors (Qm) for FeNi-FACE, PZT-8, and FeCuNbSiB enhance the resonant ME voltage due to an increased effective Qm of ME composite. Hence, a strong resonant ME response at zero-biased dc magnetic field can be obtained. The corresponding ME voltage coefficients (MEVC) at resonance for PZT/FeNi-FACE/FeCuNbSiB (FeFP) composite and FeCuNbSiB/FeNi-FACE/PZT/FeNi-FACE/FeCuNbSiB (FeFPFFe) composites achieve 2.19 V/Oe (27.375 V/cm Oe) and 3.37 V/Oe (42.125 V/cm Oe), respectively, which is ∼102 times higher than that of the previously reported NKNLS-NZF/Ni/NKNLS-NZF trilayer composite.

Theory of electromagnon resonances in the optical response of spiral magnets

The optical response of spiral magnets is studied, with special attention to its electromagnon features. We show that these features trace back to the resonant magnetoelectric response resulting from the spiral ordering (irrespective of any concomitant ferroelectricity). This response, being magnetoelectric in nature, not always can be reduced to an effective electric permittivity. We argue that electromagnons in spiral magnets can produce, in addition to the observed peaks in the optical absorption of multiferroics, a (dynamically enhanced) optical rotation and a negative refractive index behavior.

Resonant magnetoelectric response of magnetostrictive/piezoelectric laminate composite in consideration of losses

The magnetostrictive/piezoelectric (MP) laminate composite has dramatically enhanced magnetoelectric (ME) effect when operating around resonance. The theoretical analysis of the resonant ME effect is investigated using the equivalent circuit method, in which the eddy current loss, the mechanical loss and the electric loss are all taken into account. The results indicate that, the mechanical loss plays a primary role in dissipations in resonant status, and a strong bias magnetic field is essential to restrain eddy current loss and improve the ME conversion efficiency.

The resonant magnetoelectric response of magnetostrictive/piezoelectric laminated composite under the consideration of losses

The theoretical analysis of resonance magnetoelectric(ME) performances in longitude-transverse type magnetostrictive/piezoelectric laminated composite is presented in this paper based on the equivalent circuit method, and the formula of ME voltage coefficient is obtained, which is useful to the composite design and optimization. To evaluate the ME voltage coefficient near the resonance, the losses such as eddy-current loss, mechanical loss, and dielectric loss are considered and formulated, which indicates that the mechanical loss plays the key role in dissipation. The analysis, which takes losses into account, gives better explanations to current experimental values.