Resonant Magnetoelectric Coupling Research Articles

Performance analysis of acoustically actuated magnetoelectric antennas via equivalent circuit method

Acoustically actuated magnetoelectric (ME) antennas based on resonant magnetoelectric coupling within ferromagnetic/piezoelectric ME laminated composites have recently been considered as a promising solution for antenna miniaturization. However, its radiation performance has been theoretically overestimated, since the negative effects on performances due to the magnetization saturation and the nonlinear mechanical behavior that occur from high-field driving have not been paid enough attention. This work presents a unique equivalent-circuit-based numerical method to analyze the near-field resonance radiation performances of ME antennas driven by high electric fields. In this method, we establish an equivalent circuit of the converse magnetoelectric effect for a ME laminated composite to describe the operating principle of acoustically actuated electromagnetic radiation. The equivalent parameters related to resonance characteristics are determined by fitting the circuit model to the data from frequency response measurements of the near-field magnetic flux density. The validity of the model is verified by comparing the theoretical predictions with the experimental results, in the view of the volume fraction dependence of the mechanical resonance-related radiation characteristics of the fabricated ME composites. Based on the proposed model, the influence of driving voltage amplitude on near-field radiation performances is further analyzed by experimental fitting to the model, and the potential limiting factors of ME antennas are discussed according to the driving-amplitude dependence of parameters obtained from the fit. This work provides an effective and engineering-friendly approach to predict the evolution of ME antenna performances, leading a way to improve the performance limit for resonant magnetoelectric coupling.

Resonant Magnetoelectric Coupling of Fe-Si-B/Pb(Zr,Ti)O3 Laminated Composites with Surface Crystalline Layers.

The resonant magnetoelectric (ME) effect of Fe78Si9B13/Pb(Zr,Ti)O3 (FeSiB/PZT) composites with a surface-modified Fe78Si9B13 amorphous alloy has been studied. The surface-modified FeSiB can improve the ME coefficient at the resonant frequency by optimizing the magnetomechancial power conversion efficiency. The maximum ME coefficient of the surface-modified ribbons combined with soft PZT (PZT5) is two-thirds larger than that of the composites with fully amorphous ribbons. Meanwhile, the maximum value of the ME coefficient with surface-modified FeSiB ribbons and hard PZT (PZT8) is one-third higher compared with the fully amorphous composites. In addition, experimental results of magnetomechanical coupling properties of FeSiB/PZT composites with or without piezoelectric layers indicate that the power efficiency of the composites first decreases and then increases with the increase in the number of FeSiB layers. When the surface crystalline FeSiB ribbons are combined with a commercially available hard piezoelectric ceramic plate, the maximum magnetoelectric coupling coefficient of the ME composite reaches 5522 V/(Oe*cm), of which the electromechanical resonant frequency is 23.89 kHz.

Reduced resonance frequency and enhanced coupling coefficient in fishtailing magnetoelectric resonator

Reducing the resonance frequency of the first-order longitudinal vibration mode for a bulk magnetoelectric (ME) resonator has been a challenge for very low frequency (VLF) magnetic sensing and transmitting application. In this work, we design and fabricate a fishtailing ME resonator that reduces the anti-resonance frequency from 18.8 to 12.2 kHz and the resonance frequency from 18.2 to 11.5 kHz compared with conventional 1–1 typed resonator. Meanwhile, a significant enhancement of the resonant ME coupling coefficient [from ∼8271 to ∼11 400 V/(cm Oe)] is also realized. Finite element simulation and lumped mass method are used to calculate and analyze the principles of the reduced resonance frequency and the reasons for enhanced coupling performance. The geometry tailoring method in this work is believed to inspire applications of the resonant ME effect at very low frequency.

Nonlinear modeling of bending-mode magnetoelectric coupling in asymmetric composite structures with magnetization-graded ferromagnetic materials

The bending-mode magnetoelectric (ME) coupling in the asymmetric laminate composite with a magnetization-graded ferromagnetic material has been investigated in this paper. Based on the nonlinear constitutive relationships of the magnetostrictive material, the dynamic piezomagnetic models have been presented for magnetostrictive materials after considering the remanence, demagnetization, and flux concentration effects. In addition, the bending-mode resonant ME coupling model is developed based on the proposed dynamic piezomagnetic model, the motion equation of the ME composite, and the ME equivalent circuit method. The composite structures FeCuNbSiB/Ni/PZT with negative magnetostrictive Ni and FeCuNbSiB/FeNi/PZT with positive magnetostrictive FeNi have been used to confirm the validity and reliability of the theoretical model. The theoretical results show that the bending-resonant ME coefficients reasonably agree with the experimental results. This theoretical model is of importance for understanding the bending-mode ME response of the asymmetric structure with magnetization-graded ferromagnetic materials and designing the ME devices.

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.

Magnetoelectric coupling in strained strontium titanate and Metglas based magnetoelectric trilayer

Direct magneto electric coupling is observed with a magnetoelectric coupling coefficient (MECC) of 806 mV cm−1 Oe−1 at 750 Hz in strontium titanate (STO) - Metglas - strontium titanate (STO-Metglas-STO) trilayer thin films with a total thickness of 600 nm. The piezoelectricity in the strained STO layer, which is otherwise a paraelectric material, enabled the sandwiched magneto electric structure to exhibit a fair sub resonant magneto electric coupling. Theoretical models proposed by Bichurin et al. and Hasanyan et al. are employed to calculate the values of MECC at sub resonant condition for the system, which is noted as 853 mV cm−1 Oe−1. The frequency dependence of MECC coefficient is also calculated and the resonance frequency is estimated as 706 Hz.

The effects of the soft magnetic alloys’ material characteristics on resonant magnetoelectric coupling for magnetostrictive/piezoelectric composites

The resonant magnetoelectric (ME) effects are investigated in Terfenol-D/PZT laminates with various soft magnetic alloys (i.e. FeCuNbSiB, FeSiB and CoNiFeSiB). The soft magnetic alloys with high magnetic permeability and magnetization produces an additional magnetostatic field in the Terfenol-D, which changes the effective magnetic field distribution within the Terfenol-D and plays an important role at the large zero bias ME response. Meanwhile, the magnetostrictive strain of soft magnetic alloys can produce a pre-stress on the Terfenol-D layer due to its low saturation field, which enhances the maximum ME voltage coefficient and reduces the required optimal dc magnetic field Hopt,dc. The experimental results indicate that the largest zero bias ME voltage coefficient is obtained for Terfenol-D/PZT composite with FeCuNbSiB (i.e. the soft magnetic alloy with the highest magnetization), which is about 7.3 times more than that of Terfenol-D/PZT at zero bias. The maximum ME voltage coefficient is obtained for Terfenol-D/PZT composite with FeSiB (i.e. the soft magnetic alloy with the largest magnetostriction constant) at Hopt,dc = 175 Oe, which is about 1.15 times greater than that of Terfenol-D/PZT composite (at Hopt,dc = 598 Oe) and also happens at a much smaller bias field.

Strain induced giant magnetoelectric coupling in KNN/Metglas/KNN sandwich multilayers

A lead-free magnetoelectric composite with sandwich layers of K0.5Na0.5NbO3 (KNN)/Co76Fe14Ni4Si5B (Metglas)/KNN is fabricated as a cantilever and it is characterized for its magnetic, ferroelectric, and magnetoelectric properties. Giant magnetoelectric (ME) coupling is recorded under both resonant and sub resonant conditions and the data are presented here. The observed magnetoelectric coupling coefficient reaches a maximum of 1321 V/cm Oe at resonance (750 Hz) and 9.5 V/cm Oe at a sub-resonant frequency of 50 Hz. The corresponding theoretical calculations are provided for comparison. High magnetostriction as well as initial permeability, fairly good piezoelectric properties, and low dielectric constant cumulatively contribute to the giant magnetoelectric properties in the present system. The high resonance and sub resonance ME coupling voltages make the system ideal for transducers and energy harvesting device applications.

Layer thickness and sequence effects on resonant magnetoelectric coupling in Ni/Pb(Zr,Ti)O3 cylindrical composites

Ni/Pb(Zr,Ti)O3/Ni, Ni/Pb(Zr,Ti)O3 and Pb(Zr,Ti)O3/Ni cylindrical layered magnetoelectric (ME) composites with different Ni layer thickness were prepared by electrodeposition. The resonant ME effect was studied in both axial and vertical modes. The optimal DC magnetic field increases with Ni layer thickness and resonant ME voltage coefficients are maximum at intermediate Ni layer thickness for all cases. The resonant ME effect is also influenced by magnetostrictive and piezoelectric layer sequence. The Pb(Zr,Ti)O3/Ni cylinder has the best ME performance because of the highest axial ME voltage coefficient, almost highest vertical ME voltage coefficient and lowest optimal DC magnetic field in both modes. This work provides guidance to optimize ME performance in cylindrical layered ME composites.

Nonlinear resonant magnetoelectric coupling model for dual-peak phenomenon in magnetoelectric laminates

We investigated the dual-peak phenomenon in the response curve of the magnetoelectric (ME) coupling coefficient versus magnetic field for Terfenol-D/PZT/Terfenol-D tri-layer magnetoelectric laminated composites. Using nonlinear constitutive relations for the magnetostrictive material, an expression for the resonance ME coefficient that considers nonlinear resonance mechanical loss is established with the aid of the equivalent circuit method. The established model effectively predicts the complex behavior related to dual-peak phenomenon in regard to pre-stress, bias magnetic field, frequency of the alternating magnetic field, and nonlinear mechanical loss, and explains the origin of the dual peaks. The response curves obtained are consistent with experimental results. It can be found from the further predictions that in a given resonance frequency band, selecting an appropriate pre-stress can regulate two peaks in dual-peak curve, so that a giant ME coupling effect is obtained on the first peak, or a stronger resonance peak is achieved by adjusting stress to merge two peaks. With our resonance ME dual-peak model, we also demonstrate a giant ME coupling by regulating the dual-peak resonances by pre-stress engineering.

Nonlinear resonant magnetoelectric coupling effect with thermal, stress and magnetic loadings in laminated composites

Since the magnetostrictive strain and magnetization of giant magnetostrictive materials exhibit enhanced nonlinear magneto-elasto-thermal coupling characteristics under the influence of bias magnetic field, prestress and temperature, this paper adopted a 1D nonlinear magnetostrictive constitutive and the linear piezoelectric constitutive relations combined with the equivalent circuit method to establish a 1D enhanced nonlinear magneto-elasto-thermal coupling resonant magnetoelectric (ME) model for Terfenol-D/PZT/Terfenol-D laminated composites. Without considering prestress, the comparisons of curves of resonant ME coefficient peak and its corresponding resonant frequency versus temperature between the theoretical results and experimental results are in good agreement both qualitatively and quantitatively. On this basis, this paper predicted variations in resonant ME coefficient and resonant frequency under different bias magnetic fields, prestresses and temperatures. These results show that the exerted compressive stress can be reduced so as to increase the resonant ME coefficient and lower the required bias magnetic field to the maximum of ME coefficient at relatively low and stable ambient temperatures; however, in extreme temperature environment, a larger compressive stress can be exerted to suppress the dramatic attenuation of ME effect caused by extreme temperature increases. Moreover, as temperature is increased, the resonant frequency tends to increase monotonically under different prestresses.

The influence of low-level pre-stressing on resonant magnetoelectric coupling in Terfenol-D/PZT/Terfenol-D laminated composite structure

The resonant magnetoelectric coupling behavior in a Terfenol-D/PZT/Terfenol-D laminated composite structure is experimentally studied with specific interest in the dependence on the pre-applied low-level mechanical stress up to 1.25 MPa. A laminated composite consisting of two Terfenol-D plates and one transversely polarized sandwiched-in PZT plate is fabricated in lab followed by pre-stressing along the direction of length, width, and thickness, respectively. It is observed that resonant magnetoelectric coupling develops in such pre-stressed composite when magnetically excited in each of the orthogonal directions, and the longitudinal mode of principle vibration can be confirmed. The action of pre-stresses generally elevates the frequency of resonance through the ΔE effect in Terfenol-D. In the meanwhile, the increased pre-stress lowers the value of the resonance magnetoelectric coefficient. This is partly attributed to the decrease of the effective quality factor of the structure along the increase of pre-stress, and partly attributed to the piezomagnetic coefficient of Terfenol-D, which either decreases or remains constant depending on the magnetizing state. In addition to the resonant behaviors, the tunability of the magnetoelectric coefficient of the pre-stressed structure is examined at fixed excitation frequency. For the structure excited in the length or width direction, the magnetoelectric coupling can reach the maximum at an optimal bias field. When excited in thickness, however, the magnetoelectric coupling becomes very weak, and the value of the coefficient increases monotonically with the pre-stresses. The increase of the pre-stress causes degradation of the maximum magnetoelectric coefficient for the structure when excited in length or width direction. This observation can be explained via the upshift of the resonance frequency of the structure caused by increased pre-stresses. Alternatively, it can be viewed as the consequence of the change in the maximum piezomagnetic coefficient of Terfenol-D, which is observed to decrease upon the increase of pre-stresses.

Controllable resonance frequency in Ni/Pb(Zr,Ti)O3/FeCo cylindrical composites

Magnetoelectric (ME) Ni/Pb(Zr,Ti)O3/FeCo cylindrical layered composites with a negative magnetostrictive/piezoelectric/positive magnetostrictive structure have been prepared by electroless deposition. The magnetostrictive layers are in direct contact with the piezoelectric layer. The ME effect was measured by applying both constant and alternating magnetic fields parallel and perpendicular to the cylinder’s axis direction. The ME voltage coefficient increases, and the resonance frequency decreases as the cylinder diameter increases. The experimental resonance frequency is very close to the calculated ones. This characteristic of resonance frequency can be applied to design a kind of ME composites with the controllable resonance ME coupling.

Eddy-current effect on resonant magnetoelectric coupling in magnetostrictive-piezoelectric laminated composites

An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)-piezoelectric (PE) laminated composites in consideration of eddy-current effect in MS layer using equivalent circuit method is presented. Numerical calculations show that: (1) the eddy-current has a strong effect on ME coupling in MS-PE laminated composites at resonant frequency; and (2) the resonant ME coupling is then significantly dependent on the sizes of ME laminated composites, which were neglected in most previous theoretical analyses. The achieved results provide a theoretical guidance for the practice engineering design, manufacture, and application of ME laminated composites and devices.

Enhanced resonant magnetoelectric coupling in frequency-tunable composite multiferroic bimorph structures

We report on a giant tunable enhanced resonant magnetoelectric (ME) coupling in multiferroic magnetostrictive/piezoelectric composite bimorph structures. The approach uses a magnetic/electric field assisted stress-reconfigurable resonance to produce frequency tuning of up to 100%. The studies were performed by laser Doppler spectroscopy. We also show that this principle of a continuously tuned resonance might be used to improve sensitivity for ME magnetic sensors.

Large magnetoelectric effect and resonance frequency controllable characteristics in Ni–lead zirconium titanate–Ni cylindrical layered composites

Magnetoelectric (ME) Ni–PZT–Ni cylindrical layered composites have been prepared by electroless deposition. The ME effect was measured by applying both constant and alternating magnetic fields parallel and perpendicular to the cylinder axis direction. The ME voltage coefficient increases with cylinder diameter. Both experimental and calculated data indicate that the resonance frequency of Ni–PZT–Ni cylindrical layered composites decreases with increasing cylinder diameter. We can apply this characteristic of resonance frequency to design a kind of ME composites with the controllable resonance ME coupling.

Tunable resonance frequency of magnetoelectric layered composites

As magnetoelectric (ME) effect in the composites of piezoelectric and magnetostrictive phases is mediated by mechanical deformation, the ME effect is greatly enhanced at resonance frequency. To control the resonance frequency, the dimension of the layered ME Ni/PZT/Ni composites prepared by electroless deposition was adjusted. The consistency of the resonance frequencies of impedance and ME voltage coefficient suggests that the resonance ME coupling is associated with electromechanical resonance. The ME voltage coefficient increases as the length dimension increases. Both calculated and experimental data indicate that the resonance frequency of layered Ni/PZT/Ni composites decreases with increasing length. One can apply this characteristic of resonance frequency to design ME composites with tunable ME effects.

Low damping resonant magnetoelectric sensors

The signal of magnetic sensors based on resonant cantilevers comprised of elastically coupled piezoelectric and magnetostrictive materials increases as the damping decreases. Here, we demonstrate that air damping which normally is suppressed by evacuation can also be substantially reduced by lowering the resonance frequency. We show that a Si-cantilever structured to include a seismic mass features a resonant magnetoelectric coupling coefficient of 1.8 kV/cmOe at 330 Hz in air.

Enhancement of magnetoelectric coupling in a piezoelectric-magnetostrictive semiring structure

Studies on magnetoelectric (ME) coupling in a semiring of lead zirconate titanate (PZT) with a Terfenol-D insert reveal strong ME coupling at low frequencies and two orders of magnitude enhancement in the strength at resonance associated with a unique bending mode in PZT. A model is discussed for the resonance ME coupling that arises from radial and shearing displacements and theoretical estimates are in excellent agreement with the data. The model also predicts weak ME coupling in a full ring of PZT with Terfenol-D insert in agreement with the experiment. The results are of importance for ME composite based magnetic field sensors.

Resonant magnetoelectric coupling in trilayers of ferromagnetic alloys and piezoelectric lead zirconate titanate: The influence of bias magnetic field

We present the first data and theory for the bias magnetic field dependence of magnetoelectric coupling in the electromechanical resonance (EMR) region for ferromagnetic-piezoelectric heterostructures. Trilayers of Permendur, a $\mathrm{Co}\ensuremath{-}\mathrm{Fe}\ensuremath{-}\mathrm{V}$ alloy, and lead zirconate titanate were studied. Measurements of the magnetoelectric (ME) voltage coefficient ${\ensuremath{\alpha}}_{E}$ indicate a strong ME coupling in the low-frequency range and a giant ME effect due to EMR at $200--300\phantom{\rule{0.3em}{0ex}}\mathrm{kHz}$ for radial modes and at $\ensuremath{\sim}2.7\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$ for thickness modes. Data were obtained for the bias field $H$ dependence of two key parameters, the EMR frequency ${f}_{r}$ and the ME coefficient ${\ensuremath{\alpha}}_{E,R}$ at resonance. With increasing $H$, an increase in ${f}_{r}$ and a rapid rise and fall in ${\ensuremath{\alpha}}_{E,R}$ are measured. In our model we consider two mechanisms for the magnetic field influence on ME interactions: (i) a shift in the EMR frequency due to changes in compliance coefficients ($\ensuremath{\Delta}E$ effect) and (ii) variation in the piezomagnetic coefficient that manifests as a change in ${\ensuremath{\alpha}}_{E,R}$. Theoretical profiles of ${\ensuremath{\alpha}}_{E}$ vs frequency and estimates of frequency shift based on the $\ensuremath{\Delta}E$ effect are in excellent agreement with the data.