Magnetoelectric Laminate Research Articles

Theoretical model and tunability optimization of magnetoelectric voltage tunable inductor

Magnetoelectric voltage tunable inductor (ME-VTI) realizes the modulation of electric field to inductance based on magnetoelectric effect. Compared with other adjustable inductors, it has the advantages of low energy consumption, small volume, large tunability and continuity. However, previous reports on ME-VTI mainly focused on structure and magnetostrictive materials, resulting in the complexity of inductor structure and slight improvement of tunability. This study focuses on the influence of field-induced strain in piezoelectric materials on inductance tunability by constructing a theoretical model. The magnetoelectric laminate of Metglas/ PMN-PT single crystal /Metglas is employed as a magnetic core to design ME-VTI. The tunability is as high as 680% at 1 kHz, which is over 2.4 times larger than that of the Metglas/PZT/Metglas magnetic core. The quality factor of the PMN-PT based ME laminate reaches 15.6, which is 2.8 times higher than that of the PZT-based one. The proposed PMN-PT based ME-VTI provides an alternative approach for developing the integrated and miniaturized devices, and has an important prospect of application in the field of power electronics.

Theoretical optimization of magnetoelectric multilayer laminates

Magnetoelectric (ME) materials are becoming increasingly relevant in the development of new technologies for biomedical applications, sensors and actuators, among others. Mathematical models and simulations allow to optimize features and acquire fundamental knowledge on material properties to achieve innovative developments and devices. In this way, this work is focused on the simulation of both polymer-based and ceramic-based ME laminates, in order to evaluate the influence of their structure, mechanical, electrical and magnetic properties on the ME response. The effect of size and configuration has been evaluated in Vitrovac/poly (vinylidene fluoride)(PVDF) and Vitrovac/lead zirconate titanate (PZT) laminated composites. It has been established that the elastic properties and amorphous constitution of PVDF are key parameters governing its ME response, increasing its influence with increasing number of layers in the composite. Good agreement is established when comparing trends reported experimentally in the literature, presenting a curve that rapidly increases their αunit with increasing thickness ratio up to n = 0.3, when saturation is reached. Further, an optimal configuration for PZT multilayers is found, with external magnetostrictive phases and thickness ratio above 0.2, leading to a ME response of 86.7 V/cm. Finally, it has been established that PVDF configurations with external magnetostrictive phases (M-M configuration) show more stable behaviour (without the observation of random peaks) and trends over different number of layers, of about 11.5 V/cm, while P–P configurations present regions with random peaks, that is out of the expected trend and with a ME response (48 V/cm) that closer to the one obtained on ceramic multilayers.

Reducing the equivalent magnetic noise of Metglas/Mn-PMNT laminate composites via annealing treatment

The variation of dielectric loss in [1 1 0] -oriented Mn-doped 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (Mn-PMNT) single crystals after different annealing treatments, as well as their influence on equivalent magnetic noise (EMN) for magnetoelectric laminate composites, were investigated in this study. Dielectric loss can be reduced significantly in oxygen-sufficient atmosphere and high annealing temperature, and dielectric constant varies little in this annealing process, which is favorable to the decrease of the dielectric loss noise. The temperature dependence of dc conductivity was used to characterize the change of dc conductivity and activation energy, which indicated that oxygen vacancies in Mn-PMNT single crystals can be reduced by the annealing treatment, leading to the decrease of dielectric loss. For the influence of magnetoelectric laminate composites, the EMN is clearly reduced in low frequency range (10 < f < 100 Hz) after annealing treatment, which is in good agreement with the simulation results.

Enhancement of magnetoelectric (ME) coupling by using textured magnetostrictive alloy in 2-2 type ME laminate

Abstract In this study, we have investigated the effect of crystallographic orientation of magnetostrictive Galfenol (Fe83Ga17) on magnetoelectric (ME) coupling in 2-2 type ME laminates. (001) oriented Galfenol is fabricated by directional solidification method and textured along with two different directions, i.e., (001) along the length direction and (001) along the thickness direction and laminated with piezoelectric 32-mode PMN-PZT single crystal to form ME laminates. The length textured Galfenol shows 37% higher magnetostriction than that of thickness textured Galfenol. Similarly, ME laminate with length textured Galfenol (32-L) possesses higher ME coefficients than that of ME laminate with thickness textured Galfenol (32-T) at both the off-resonance and resonance conditions. At the resonance frequency, 32-L laminate showed around 150% higher direct and converse ME coefficients as compared to that of 32-T laminate owing to the higher magnetostriction of length textured Galfenol.

Structural and multiferroic properties of trilayer green magnetoelectric Co0.8Ni0.2Fe2O4/K0.25Na0.75NbO3/Co0.8Ni0.2Fe2O4 composite structure

We have investigated the structural, dielectric, magnetic-magnetostrictive, ferroelectric-piezoelectric and magnetoelectric (ME) properties of green (Pb-free) Co0.8Ni0.2Fe2O4/K0.25Na0.75NbO3/Co0.8Ni0.2Fe2O4 (CNFO/KNN/CNFO) trilayer laminate (2-2) multiferroic composite structure. Magnetostrictive Co0.8Ni0.2Fe2O4phase was synthesized by the solution combustion technique and the piezoelectric K0.25Na0.75NbO3 phase was synthesized by a solid-state method. The trilayer ME laminate composite structure of CNFO-KNN phases fabricated by silver epoxy adhesive bonding technique. The magnetostrictive Co0.8Ni0.2Fe2O4 phase exhibits a piezomagnetic coefficient of −0.029 ppm/Oe at 1500 Oe magnetic field. The piezoelectric K0.25Na0.75NbO3 showed a piezoelectric charge coefficient of d33 ~57 pC/N. The trilayer CNFO/KNN/CNFO laminate structure reveals the ME coefficient (αME) of 3.06 mV/Oe·cm which is relatively higher than the 0–3 connectivity composite structures. Here, we have discussed the fabrication technique for multiferroic laminate structures for the green magnetoelectric device having αME ~3.06 mV/Oe·cm with their magnetic/magnetostrictive and ferroelectric/piezoelectric properties.

Dimension effects of a magnetoelectric gyrator with FeCoSiB/Pb(Zr,Ti)O3 layered composites core for efficient power conversion

A Magneto-Electric (ME) gyrator with a superior power efficiency of 95 % has been achieved based on a two-phase solid-state ME laminate. This ME gyrator consists of a winding coil that generates a magnetic field as the first step to realize electromagnetic energy transfer. A magneto-electric composite, serving as the second step, then converts the power from magnetic to electric forms. The laminate consists of two iron-cobalt based amorphous alloy layers bonded to a lead zirconate titanate plate. It has a giant magneto-electric coefficient of around 2200 (V/cm)/Oe at its mechanical resonant frequency (≈ 44 kHz) in structure. Approaching methods based on maximum power transfer (MPT) efficiency theory and the equivalent loss factor (ELF) from the input port have been introduced to evaluate the power efficiency of the ME gyrator. The expected MPT efficiency is 96.5 % at a power volume density of 0.1 W/in3 (6.1 mWatt/cm3), and 93.2 % up to 20 W/in3 (1.22 W/cm3). The ELF explains that the magnetomechanical conversion efficiency is related to the volume of the magnetic phase which is the dominating term in the power efficiency.

Designing ferroelectric/ferromagnetic composite with giant self-biased magnetoelectric effect

We report a simple and effective method to obtain the magnetoelectric (ME) effect at zero magnetic bias field (HDC = 0), i.e., the self-biased ME (SME) effect, using an ME laminate composite clamped at its center with its free ends loaded with magnetic tip masses. The method exploits the shifting of the magnetic hysteresis loop of the ferromagnetic (FM) layer of the laminate induced by a preapplied magnetic field (Hp) along the longitudinal direction. The optimum magnetic-field strength corresponding to the maximum of the ME voltage coefficient (αME) vs HDC curve was calculated using equations derived from correlations of magnetic coefficients. In experiments involving the laminate with an FM/ferroelectric/FM symmetrical structure, the strength of Hp was tuned to the optimum value, shifting the αME vs HDC curve along the HDC axis enough to obtain the maximum αME at HDC = 0 (αSME). To further enhance αSME, an asymmetric configuration of the laminate was designed using two different FM materials having piezomagnetic coefficients with opposite signs. The ME laminate with the asymmetrical structure exhibited a large αSME of 55.7 V cm−1 Oe−1 at its bending resonance frequency.

A low-power and high-sensitivity magnetic field sensor based on converse magnetoelectric effect

Tremendous progress has been made in boosting the realization of magnetoelectric (ME) magnetometers based on the direct ME effect (DME) for bulk ME laminates. In this work, we studied the potential of an electrically driven bulk magnetic field sensor based on the converse ME effect (CME). Starting from a discussion about the dependence of the induced voltage from the pickup coil on coil parameters and the CME coupling process, we then experimentally measured the optimized bias field in the off resonance region and observed the double-peak phenomenon that occurred within the resonance window. More importantly, the optimization with respect to the sample's dimension, excitation voltage, and frequency was conducted to improve the sensing capability for low-frequency magnetic fields. It was experimentally found that a limit of detection (LoD) of ∼115 pT for a magnetic field of 10 Hz and ∼300 pT for a magnetic field of 1 Hz was achieved when exciting the ME laminate at 1 V without any bias field. In this case, the power consumption for the ME laminate is only 0.56 mW, which is much lower compared to tens of milliwatts (10–100 mW) for optically pumped or flux gate sensors (excluding the power consumption from the electronics) and also shows advantages over conventional ME magnetic field sensors based on DME with a current pump.

Enhanced self-bias magnetoelectric effect in locally heat-treated ME laminated composite

This study reports the improvement in the magnetoelectric (ME) coupling effect in a locally heat-treated FeBSi (Metglas)/Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 single crystal laminated composite under zero magnetic bias. The high-temperature pulse laser treatment could induce local crystallization along the laser scanning line, but adjacent domains remained still amorphous, which resulted in the thermal and lattice mismatch. Therefore, it could produce a residual stress between the crystalline and amorphous phases, which generated an internal bias field in the Metglas foil. The experimental results showed that the ME coefficient for the laser-treated laminate was enhanced to 1220 V/cm Oe at the resonance frequency of 23.32 kHz without a magnetic bias, which was two times higher than that of the untreated ME laminates. The induced ME voltage also showed a linear response to the applied AC magnetic field with an amplitude as low as 10−10 T at the resonance. The excellent ME performance could, therefore, serve as a promising and practicable application for highly sensitive magnetic field sensors under the zero bias field.

Undistorted 180° phase reversal of magnetoelectric coupling in bi-layered multiferroic laminate

A methodology of rotating the applied static magnetic field on Ni0.8Zn0.2Fe2O4 (NZFO)/PZT-8 magnetoelectric laminate, was introduced to realize 180° phase reversal with constant amplitude, which is invariably required for phase-based communication system, engineering technology and microelectronic devices. Through further decoding the phase information existed in magnetoelectric coefficient, we found that the undistorted 180° phase reversal can be achieved once the applied field was reversed. Moreover, piezomagnetic response can essentially track the magnetoelectric response under optimum bias with the variations of rotation angle, and then the origins can be well explained. Experimental results show that the maximum resonance ME voltage coefficient of +51.72 V/cm Oe and −51.93 V/cm Oe were obtained in angle of θ = 0° and 180°, respectively. These results provide great possibilities for practical applications in ME phase shifters and inverters.

Electric-field-controlled frequency tunability enhancement by samarium light doping in PZT/Ni–Zn ferrite/PZT magnetoelectric composites

Electric-field-controlled resonance tuning in tri-layer magnetoelectric laminate consisting of Ni–Zn ferrites (with/without Sm-doped) and PZT plates has been performed and systemically characterized. By applying the DC voltage on PZT plate, modulus of the sample will change in ferrite which is caused by mediated pre-stress from PZT plate, resulting in a resonance shifting without a sacrifice of MEVC decay. For the purpose of tuning range improvement, light doping of samarium was employed in spinel nickel–zinc ferrites to modify frequency responses properties. Experimental results showed that a nearly linear variation of resonance frequency with applied voltage varied from 0 to 6 kV/cm was obtained. Consequently, the resonance frequency can be precisely controlled by the pre-stress generated from DC electric field. In addition, the tunability of resonance frequency exhibits an approximately 3.68 times enhancement by samarium doping in the Ni–Zn ferrites. The pathway for resonance frequency tunable realization by applied DC voltage provides an accurate tuning method for the tunable resonator, which can be deployed extensively in signal generators, phase shifters and other electronic devices.

Effect of Structural Control on the Magnetoelectric Characteristics of Piezoelectric–Magnetostrictive Laminate Composite in Resonance and Off-Resonance Modes

In this study, it is reported that the magnetoelectric (ME) performance in the resonance mode and that in the off-resonance mode are reversed depending on the thickness fraction of the piezoelectric layer in a ME laminate composite composed of piezoelectric and magnetostrictive layers. The ME performance in the resonance mode increased as the thickness fraction of the piezoelectric layer was increased, while the ME performance in the off-resonance mode decreased. Based on the impedance spectrum analysis of fabricated ME laminate samples, it was confirmed that the thickness fraction of the piezoelectric layer had a significant influence on the mechanical loss of the device. The phase angle change and the mechanical quality factor at the anti-resonance frequency of the ME laminate were found to be useful for predicting the ME performance in the resonance mode. High aspect ratio of the laminate was favorable in both resonance and off-resonance modes.

Modeling of a Magnetoelectric Laminate Ring Using Generalized Hamilton's Principle.

The mathematical modeling of the magnetoelectric (ME) effect in ME laminates has been established for some simple structures. However, these methods, which are based on the differential equation approach, are difficult to use in other complex structures (e.g., ring structures). In this work, a new established approach based on the generalized Hamilton’s principle is used to analyze the ME effect in an ME laminated ring. Analytical expressions for ME voltage coefficients are derived. A comparison with the conventional method indicates that this approach is more convenient when the modeling analysis is performed on complex structures. Further, experimental data are also obtained to compare with the theoretical calculations in order to validate the new approach.

Self-biased magnetoelectric current sensor based on SrFe12O19/FeCuNbSiB/PZT composite

This paper presents a packaged current sensor based on a SrFe12O19/FeCuNbSiB/PZT self-biased magnetoelectric (ME) cantilever. The hard magnetic material of the SrFe12O19 ribbon with a large coercive field provides a huge internal magnetic field to bias the magnetostrictive FeCuNbSiB(Fe73.5Cu1Nb3Si13.5B9) layers, which can increase the magnetic moment reorientation of FeCuNbSiB layers. Consequently, by coupling the vortex magnetic field around a current-carrying cable, the proposed SrFe12O19/FeCuNbSiB/PZT sensor has a large output voltage and electric current sensitivity without additional DC bias magnetic field. Experimental results demonstrate that the presented sensor has a higher sensitivity of 198.91 mV/A at 50 Hz and the induced output voltage shows a good linear relationship to the applied 50 Hz current. Also, the SrFe12O19/FeCuNbSiB/PZT sensor can distinguish small step changes of ˜0.01 A current. These results provide a significant advancement toward promising application of the trilayer self-biased ME laminate for power-line electric monitoring.

Magnetic and magnetoelastic parameters affecting the magnetoelectric response in L-T mode working metallic glass/PVDF laminated composites

Abstract A deep study of magnetic and magnetoelastic parameters affecting the magnetoelectric response of laminated composites working on longitudinal-transverse (L-T) mode has been carried out. Parameters such as the piezomagnetic coefficient of the magnetostrictive ribbons and the quality factor of the laminates have been analyzed in 3, 2, 1 and 0.5 cm long Fe64Co21B15/polyvinylidene fluoride (PVDF)/Fe64Co21B15 magnetoelectric composites. The obtained results show that the product of piezomagnetic coefficient and the quality factor drives the magnetoelectric response in magnetoelectric laminates, as the theoretical equations predict. Furthermore, the magnetoelectric coupling factor has been deduced from the ratio between the experimental and the expected magnetoelectric coefficients, with maximum coupling values up to 0.89 obtained for the longest laminate.

Effects of remanent magnetization on dynamic magnetomechanical and magnetic-sensing characteristics in bi-layer multiferroics

Influences of remanent magnetization on dynamic magnetomechanical mechanisms in a bi-layer asymmetric magnetoelectric (ME) laminate consisting of lead zirconate titanate and samarium iron alloy has been studied systematically, and the underlying hysteresis physics involved in dynamic magnetomechanical process as well as its magnetic-sensing characteristics was intensively characterized. To appreciate the distinct magnetostriction and ferromagnetism simultaneously in samarium iron alloy, key magnetomechanical parameters of dynamic piezomagnetic coefficient, Young's modulus and mechanical quality factors exhibit hysteresis behaviors under magnetic field application. Consequently, high sensitivity in proposed bi-payer laminate for field detection can be reached without the facilitation of additional bias field. Experimental results show that the ME output has an approximately linear correlation with the applied AC magnetic field, and the low-frequency and the detection limits at 1 kHz and 120 kHz can reach 2.3 × 10−6 T and 2.2 × 10−8 T, respectively. These unique features provide such an asymmetric ME composite great potentials for weak magnetic field detection without DC bias field.

A passive isolator realized by magnetoelectric laminate composites

This work demonstrates a passive isolator realized by magnetoelectric laminate composites. The proposed isolator consists of a magnetoelectric gyrator, two impedance matching networks, and a load impedance. The equivalent circuit model of the isolator is developed. Good agreement has been obtained between the measured and computed results based on the proposed equivalent circuit model. The measured forward insertion loss and reverse isolation of the proposed isolator are 4.7 dB and 19 dB, respectively. A figure-of-merit which determines the performance of the isolator is proposed, which can be used to guide the design of such isolators.

Anomalous eddy-current effect of magnetostrictive-piezoelectric laminated composites in consideration of magnetic domain wall displacements

An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)- piezoelectric (PE) laminated composites taking consideration of anomalous eddy current effect resulted from the magnetic domain wall displacements in MS layer is proposed based on the equivalent circuit method. Numerical results show that: (1) the anomalous eddy-current loss deteriorates the ME coupling effect and reduces the optimal thickness ratio of MS phase to 0.3 in ME laminate. (2) the nonlinear effect between the ME coefficients and the thickness of ME laminate becomes stronger when considering the anomalous eddy-current loss. Furthermore, the proposed model can be reduced easily to the existing model considering of the classical eddy-current effect.

Rotating Magnetoelectric Sensor for DC Magnetic Field Measurement

Magnetoelectric (ME) sensors have a significant potential for detection of weak magnetic fields if the mechanical resonance is utilized. Generally, magnetic and electric modulations can be employed for frequency conversion during dc or small ac signal measurements. In this paper, we perform frequency conversion using a rotating ME sensor, which enables us to detect a dc magnetic field without any additional excitation. The sensor, consisted of L–T mode ME laminates whose magnetostrictive layers are magnetized along the length directions but piezoelectric layers are poled along the thickness directions, is more sensitive to a magnetic field along its longitudinal direction. By rotation, the dc magnetic field to be measured generates a sinusoid component in the direction of the sensor’s longitudinal axis, which is equivalent to applying an excitation. The experimental results are consistent with the theoretical calculations and demonstrate the feasibility of this proposed modulation method.

Effect of Dimension Control of Piezoelectric Layer on the Performance of Magnetoelectric Laminate Composite

Effect of Dimension Control of Piezoelectric Layer on the Performance of Magnetoelectric Laminate Composite