Self-biased Magnetoelectric Effect Research Articles

Modeling and performance analysis of resonant self-biased magnetoelectric transducers

Compared with single-phase multiferroic materials, magnetoelectric (ME) composites composed of piezoelectric and magnetostrictive materials have great ME coupling, and have received widespread attention in various application fields. The application of ME devices in wireless power transfer (WPT) is attractive due to their compactness and ability to operate at lower frequencies than conventional coils. However, traditional ME composites rely on permanent magnets or electromagnets to provide biased magnetic fields, thus leading to problems such as high noise, large size, and high cost, which significantly hinder the advancement of miniaturized and high-performance ME devices. To solve this problem, a self-biased ME laminated structure based on the magnetization grading effect is proposed in this work. Using the equivalent magnetization and nonlinear magnetostrictive constitutive relationship, a finite element simulation model for a self-biased ME transducer operating in L-T mode is constructed. The ME coupling performances without DC bias in bending vibration mode and stretching vibration mode are studied. Based on the model, the corresponding experimental samples are prepared for measurement. The measurement results are in agreement with the simulation data, thereby validating the accuracy and effectiveness of the model. The measured results show that the Metglas/Galfenol/PZT-5A structure can exhibit more significant self-biased ME effect under the stretching resonance mode than under bending resonance mode. Its ME coefficient attains a notable value of 10.7 V·cm<sup>–1</sup>·Oe<sup>–1</sup> at 99.4 kHz, while ME power coefficient reaches 5.01 μW·Oe<sup>–2</sup> at 97.9 kHz. Its on-load ME power coefficient can reach up to 4.62 μW·Oe<sup>–2</sup> at 99.3 kHz without impedance matching. When an external bias magnetic field of 25 Oe is applied, these performance indexes increase significantly to 47.06 V·cm<sup>–1</sup>·Oe<sup>–1</sup> at 99.4 kHz and 82.13 μW·Oe<sup>–2</sup> at 99.0 kHz, respectively. The simulation results further show that the performance of the self-biased ME transducer can be significantly improved by increasing the thickness of the high permeability layer. For example, by increasing the Metglas layer thickness from 30 μm to 90 μm, both the ME coefficient and ME power coefficient increase rapidly by 2.47 times and 6.96 times the original values, respectively. Self-biased ME transducers effectively reduce the dependence on external bias magnetic field, thereby providing a good approach for applying and developing ME composites in low-frequency WPT systems.

Self‐biased magnetoelectric composite for energy harvesting

AbstractThe wireless sensor network energy supply technology for the Internet of things has progressed substantially, but attempts to provide sustainable and environmentally friendly energy for sensor networks remain limited and considerably cumbersome for practical application. Energy harvesting devices based on the magnetoelectric (ME) coupling effect have promising prospects in the field of self‐powered devices due to their advantages of small size, fast response, and low power consumption. Driven by application requirements, the development of composite with a self‐biased magnetoelectric (SME) coupling effect provides effective strategies for the miniaturized and high‐precision design of energy harvesting devices. This review summarizes the work mechanism, research status, characteristics, and structures of SME composites, with emphasis on the application and development of SME devices for vibration and magnetic energy harvesting. The main challenges and future development directions for the design and implementation of energy harvesting devices based on the SME effect are presented.

Tunable self-biased magnetoelectric effect in magnetization-graded magnetoelectric composites

Magnetoelectric (ME) composites, which are magnetostrictive-piezoelectric composites, have garnered attention for use in various application fields owing to their large ME coupling compared with single-phase multiferroic materials. The maximum ME coupling is observed when an increased DC magnetic bias field is applied, which results in large devices with degraded sensitivity due to electromagnetic noise. To address this problem, a strong self-biased ME composite that generates the maximum ME response in a zero-bias field was proposed in this study. Highly self-biased ME composites were prepared by combining soft magnetic Ni and highly permeable Metglas magnetostrictive layers with a Pb(Mg1/3Nb2/3)O3–PbZrTiO3 piezoelectric single-crystal laminate structure and inducing a magnetization gradient. The maximum ME voltage value without a DC bias field was evaluated to be 4.2 V/cm∙Oe for an MMNPNMM (M: Metglas foil, N: nickel, P: PMN-PZT) structure, which is 625 % higher than that of conventional ME composites. Therefore, the relatively bulky means of the DC-bias application on ME materials could be eliminated, resulting in a simple ME device with a small volume using the magnetization gradient concept.

Giant magnetoelectricity in soft materials using hard magnetic soft materials

Imagine a material that will produce electricity via a contactless, wireless signal. Further, we hope that this material is capable of large deformation reminiscent of soft robots and is soft enough to conform to irregular or curved geometries. This would all be possible if soft magnetoelectric materials were available; paving the way for applications such as remote drug delivery, energy harvesting, soft robots, multiple state memories among others. Here, for the first time, using the concept of hard magnetic soft matter in combination with electrets, we design and create a soft magnetoelectric material that exhibits an extremely strong, self-biased magnetoelectric effect. Further, using programmable pattern of deposition of magnetic dipoles and charges, we report a giant magnetoelectric coefficient in an ultra-soft deformable material that retains its strength even under infinitesimal external fields and at low frequencies.

Self-biased Metglas/PVDF/Ni magnetoelectric laminate for AC magnetic sensors with a wide frequency range

In this work, an arc-shaped Metglas/polyvinylidene fluoride (PVDF)/Ni laminate is proposed, which exhibits a large self-biased magnetoelectric (ME) effect due to the internal magnetization gradient field between the two magnetic layers and the built-in stress formed from the arc-shaped structure. The ME coefficients reach 38.24 and 15.0 V cm−1 Oe−1 without a DC bias magnetic field at resonance and nonresonant frequencies, respectively. The sample shows a high sensitivity, resolution and linearity with values of 210.07 mV Oe−1, 1 nT and 0.9999 at the resonance frequency, respectively. The sample was then used to detect AC magnetic fields with different nonresonant frequencies (ranging from 1 to 25 kHz), resulting in the measured data being in good agreement with the actual data. Under a zero bias magnetic field and at frequencies of 40 and 1 Hz, the limit of detection can reach 2 and 8 nT, and the resolution can reach 1 and 4 nT, respectively. The results indicate that the arc-shaped Metglas/PVDF/Ni laminate shows a large self-biased ME effect and good AC magnetic sensing performance in the bending state, which provides a new way to develop a wide frequency range AC magnetic sensor.

Self-biased magnetoelectric switching at room temperature in three-phase ferroelectric–antiferromagnetic–ferrimagnetic nanocomposites

Magnetoelectric systems could be used to develop magnetoelectric random access memory and microsensor devices. One promising system is the two-phase 3-1-type multiferroic nanocomposite in which a one-dimensional magnetic column is embedded in a three-dimensional ferroelectric matrix. However, it suffers from a number of limitations including unwanted leakage currents and the need for biasing with a magnetic field. Here we show that the addition of an antiferromagnet to a 3-1-type multiferroic nanocomposite can lead to a large, self-biased magnetoelectric effect at room temperature. Our three-phase system is composed of a ferroelectric Na0.5Bi0.5TiO3 matrix in which ferrimagnetic NiFe2O4 nanocolumns coated with antiferromagnetic p-type NiO are embedded. This system, which is self-assembled, exhibits a magnetoelectric coefficient of up to 1.38 × 10–9 s m–1, which is large enough to switch the magnetic anisotropy from the easy axis (Keff = 0.91 × 104 J m–3) to the easy plane (Keff = –1.65 × 104 J m–3). A three-phase system that is composed of a ferroelectric Na0.5Bi0.5TiO3 matrix in which ferrimagnetic NiFe2O4 nanocolumns coated with antiferromagnetic p-type NiO are embedded exhibits self-biased magnetoelectric switching at room temperature.

Poly(vinylidene fluoride-trifluoroethylene)/cobalt ferrite composite films with a self-biased magnetoelectric effect for flexible AC magnetic sensors

With the rapid development of artificial intelligence and wearable devices, flexible magnetic sensors have attracted much attention in recent years. In this work, large self-biased 0–3 type poly(vinylidene fluoride-trifluoroethylene)/cobalt ferrite (P(VDF-TrFE)/CoFe2O4) flexible magnetoelectric (ME) composite films are proposed for the development of AC magnetic sensors. P(VDF-TrFE)/CoFe2O4 composite films with CoFe2O4 nanoparticle mass contents from 5 to 30% are successfully fabricated through the solution casting method. The results show that the nanoparticles are homogeneously dispersed in the P(VDF-TrFE) matrix, and the composite films have both excellent ferroelectric and ferromagnetic properties. The P(VDF-TrFE)/CoFe2O4 composite films all exhibit a large ME effect. The ME coefficient reaches 47.1 mV·cm−1·Oe−1 for the film with a CoFe2O4 nanoparticle mass content of 20% at resonance frequency. Moreover, the composite films have a large self-biased ME effect with a maximum value of 20.4 mV·cm−1·Oe−1, which is mainly due to the high remnant magnetization of CoFe2O4 nanoparticles. To evaluate the composite films for application in magnetic sensors, the response of the ME output voltage to an AC magnetic field without a bias DC magnetic field was measured. The good linear correlation coefficient, sensitivity and repeatability indicate that the proposed 0–3 type P(VDF-TrFE)/CoFe2O4 composite film is a promising material for flexible AC magnetic sensors.

Theoretical study on self-biased magnetoelectric effect of layered magnetoelectric composites

By introducing a high permeability material into the traditional magnetoelectric (ME) composite, a non-zero ME coefficient can be obtained when the external DC magnetic field is zero. This is called the self-biased ME effect. In this system, the high permeability material can be regarded as a special ferromagnetic material. A magnetic field will be generated around it, which affects the internal magnetic field distribution of the ferromagnetic phase in the ME composite. In this paper, we consider the multi-field coupling characteristics of the ME composites, the non-linear characteristics of the individual component materials, and the mechanical and magnetic properties of the high permeability material, to develop a theoretical model for such self-biased ME effect. Then the finite element method is employed to solve the Maxwell equations for this complex problem. The developed theory is highlighted with a direct comparison with experiments that shows their close agreement. It is also demonstrated that, with the addition of the high permeability material, the self-biased ME coefficient can account for 47% of the maximum ME coefficient. This remarkable outcome, and the detailed distributions of the magnetic field, electric field, and elastic field inside ME structures are also presented in detail. Finally, the influence of temperature on the ME effect of the two structures was also studied, and the results showed that the higher the temperature, the smaller the ME coefficient of the structures.

Giant Self-biased Magnetoelectric Effect in Pre-biased Magnetostrictive–Piezoelectric Laminate Composites

In this study, it is demonstrated that the giant self-biased magnetoelectric (SME) response can be achieved from a center-clamped magnetostrictive–piezoelectric laminate composite by employing magnetic tip masses. An asymmetric laminate structure consisting of two different magnetostrictive layers (Metglas and nickel) with opposite signs of piezomagnetic coefficient is introduced to promote structural bending resonance, and the effect of layout change of attaching the magnetic tip masses on SME responses is systematically investigated. The highest SME effect is observed when all magnetic tip masses are loaded on the Metglas layer and their magnetization directions are normal to the Metglas surface. It is proposed that not only the parallel magnetic domains to external magnetic field but also the non-parallel magnetic domains effectively contribute to the total magnetostriction. The fabricated SME laminates exhibit giant SME voltage coefficients ranging from 14.11 to 52.35 V cm−1 Oe−1, depending on the direction of the fields of the tip magnets. These high SME voltage output values and their controllability are promising for precision field sensors, magnetic energy harvesters and field-tunable devices.

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.

Electric field poling induced self-biased converse magnetoelectric response in PMN-PT/NiFe2O4 nanocomposites

In this letter, studies on structural transitions and the effect of electric field poling on magnetoelectric (ME) properties in 0.65Pb (Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT)/NiFe2O4 (NFO) nanocomposites are reported. The composite illustrates dramatic changes in the NFO crystal structure across ferroelectric transition temperature [Curie temperature (Tc) ∼ 450 K] of PMN-PT, while pure NFO does not exhibit any structural change in the temperature range (300 K–650 K). Synchrotron based X-ray diffraction analysis revealed the splitting of NFO peaks across the Tc of PMN-PT in the PMN-PT/NFO composite. Consequently, the anomalies are observed in temperature dependent magnetization of the NFO phase at the Tc of PMN-PT, establishing ME coupling in the PMN-PT/NFO composite. Furthermore, the composite exhibits drastic modification in ME coupling under electrically poled and unpoled conditions. A large self-biased ME effect characterized by non-zero ME response at zero Hbias was observed in electrically poled composites, which was not observed in unpoled PMN-PT/NFO. These results propose an alternative mechanism for intrinsic converse ME effects. The maximum magnetoelectric output was doubled after electrical poling. The observed self-biased converse magnetoelectric effect at room temperature provides potential applications in electrically controlled memory devices and magnetic flux control devices.

Integration of c-axis oriented Bi3.15Nd0.85Ti2.95Hf0.05O12/La0.67Sr0.33MnO3 ferromagnetic-ferroelectric composite film on Si substrate

A La0.67Sr0.33MnO3 (LSMO) ferromagnetic layer and a Nd3+/Hf4+ co-substituted Bi4Ti3O12 (Bi3.15Nd0.85Ti3-xHfxO12 (BNTHx, x = 0, 0.025, 0.05, 0.1 and 0.15)) ferroelectric layer were successively deposited onto the (00 l)-oriented LaNiO3 (LNO) layer buffered (001) Si substrate via all chemical solution deposition (CSD) method. As a result, the BNTHx/LSMO ferromagnetic-ferroelectric composite films integrated on Si substrate exhibit high c-axis orientation. The Nd3+/Hf4+ co-substituted BNTHx films have the lower leakage current and the better ferroelectric properties than the mono-substituted Bi4Ti3O12 (Bi3.15Nd0.85Ti3O12 and Bi4Ti2.95Hf0.05O12) films. In particular, the BNTH0.05/LSMO/LNO film has the lowest leakage current density of 2.5 × 10−7 A/cm2 at 200 kV/cm, and the highest remnant polarization (Pr) of 27.3 μC/cm2. The BNTH0.05/LSMO/LNO composite film also exhibits the soft ferromagnetism characteristics with a high saturated magnetization of 258 emu/cm3 at 300 K, and the excellent magnetoelectric (ME) effect. The variations of ME voltage coefficient αE values with DC bias magnetic field Hbias shows that the BNTH0.05/LSMO/LNO film has the high αE value at near zero Hbias. Moreover, at Hbias = 0 Oe, the αE value gradually increases from zero with the increasing of the AC magnetic field frequency, and eventually reaches about 18.9 V/cm·Oe at 100 kHz, suggesting the existence of self-biased ME effect.

Room temperature large self-biased magnetoelectric effect in non-lead based piezoelectric and magnetostrictive (0−3) particulate composite system

In this work, room temperature magnetoelectric properties of (0−3) particulate composites of non lead based piezoelectric BNTKNNLTS [0.97(Bi0.5Na0.5TiO3)–0.03(K0.47Na0.47Li0.06Nb0.74Sb0.06Ta0.2O3) and magnetostrictive CZFMO (Co0.6Zn0.4Fe1.7Mn0.3O4) are presented. Composite samples of (1-x)(BNTKNNLTS)-x(CZFMO), with x=0.1 and 0.5, are synthesized by solid state reaction route. X-ray diffraction confirms the single phase formation of parent phases and the presence of two phases in the composites. Similar sintering conditions of the two individual components lead to optimal ferroelectric and ferromagnetic properties in the composites. A large self-biased magnetoelectric (ME) coupling ~74mV/cm.Oe for the sample with x=0.1 (measured in longitudinally magnetized-transversely polarized configuration) is observed at room temperature.

A cost-effective self-biased magnetoelectric effect in SrFe12O19/Metglas/Pb(Zr,Ti)O3 laminates

By introducing the hard magnetic SrFe12O19 ribbon, a self-biased magnetoelectric laminate—SrFe12O19/Metgals/Pb(Zr,Ti)O3 was successfully designed. Without any external magnetic field, the laminates exhibit giant self-biased ME responses of 1 V (cm Oe)−1 at quasi-static condition, and up to 29 V (cm Oe)−1 at high-frequency resonance. The induced ME voltage shows a good linear relationship to the applied ac magnetic field with amplitude as low as 10−8 T at 1 kHz, and the self-biased ME property presents an outstanding stability in a time span of 12 months.

Self-biased magnetoelectric effect in (Pb, Zr)TiO3/metglas laminates by annealing method

FeBSiC metglas was annealed at an optimized condition (350°C, 5min) to achieve the mixed phases with pristine amorphous phase and crystallization phase. With such annealed metglas, a self-biased magnetoelectric (ME) laminate of metglas/Pb(Zr, Ti)O3/metglas was fabricated. Without any external magnetic field, the composite exhibits the ME coefficient αE31 of 103mV/(cm Oe) at 1kHz and 15.5V/(cm Oe) at electromechanical resonance frequency. The induced ME voltage shows a good linear relation to the applied AC magnetic field with amplitude as low as 10−7T at 1kHz. It is expected that such self-biased ME composites provide a practical application of economical and compact magnetic sensors.

A mechanical-thermo-magneto model for self-biased magnetoelectric effect in laminated composite

In this paper, a mechanical-thermo-magneto model for self-biased magnetoelectric effect in laminated composite with high-permeability materials is established. Considering the effects of demagnetization, pre-stress and temperature, the effective magnetic field and piezomagnetic coefficient of magnetostrictive layers are calculated. Then, the effects of temperature and pre-stress on ME effect are investigated. Finally, the combined effect of temperature and pre-stress on zero-bias ME voltage coefficient is discussed in detail to achieve a good ME conversion efficiency. The numerical results show that due to the occurrence of the additional magnetic field from high-permeability materials, available self-biased ME effect can be obtained in the proposed model. The operating temperature affects not only the peak value but also the initial value of ME voltage coefficient. Also, pre-stress can change the temperature effect on the zero-bias ME voltage coefficient obviously.

Enhanced self-biased direct and converse magnetoelectric effect in Pb(In1/2Nb1/2)O3–PbTiO3/NiFe2O4 bi-layer laminate composite

The direct magnetoelectric (DME) effect and converse magnetoelectric (CME) effect are investigated in bi-layer ferroelectric [0.65 Pb(In1/2Nb1/2)O3–0.35 PbTiO3]–ferrite [NiFe2O4] laminate composite prepared by epoxy bonding. The magnetoelectric (ME) properties of bi-layer composite is studied at low frequency (1 kHz) and at electromechanical resonance frequencies under external bias field (H dc ). The laminate composite shows a DME coefficient (α DME ) and CME coefficient (α CME ) of 103 mV/(cm Oe) and 0.04 (mG cm)/V respectively at 1 kHz with a H dc of 110 Oe. Moreover the α DME and α CME shows non-zero value in the absence of external bias field, which signifies the presence of self-biased ME effect in this laminate composite. Under resonance condition, ME coupling enhanced two orders of magnitude compared to low frequency value. A large self biased α DME of 8 V/(cm Oe) and α CME of 5 (mG cm)/V is achieved at electromechanical resonance.

Large self-biased effect and dual-peak magnetoelectric effect in different three-phase magnetostrictive/piezoelectric composites

We investigate magnetoelectric (ME) effects in various three-phase laminate composites of FeCuNbSiB/Terfenol-D/PZT(FeMP), FeCuNbSiB/iron–nickel-based ferromagnetic alloy with constant elasticity/PZT(FeFP) and FeCuNbSiB/Ni/PZT(FeNiP). Under the low frequency and resonant frequency condition, various composites exhibit hysteretic ME responses as a function of applied bias field. Both self-biased effect characterized by non-zero ME effect at zero bias and dual-peak ME effect are observed. Especially, self-biased ME properties are remarkably enhanced at resonance. The zero-biased ME coefficient for FeNiP with a high quality factor of 551.79 reaches 10.12V/Oe (126.625V/(cmOe)), which is 4.34 times and 19.84 times larger than those of FeFP (2.33V/Oe) and FeMP (0.51V/Oe) composites, respectively. These results provide the possibility of implementing self-biased ME effect in high-sensitivity magnetic-sensing devices.

Self-biased Dual-phase Energy Harvesting System

ABSTRACTIn this study, we report the design and fabrication of a dual-phase energy harvester which can synchronously harvest both mechanical and magnetic energy in the absence of DC magnetic field. The harvester consists of a magnetostrictive cantilever beam and a magnetostrictive/ piezoelectric (M/P) self-biased laminate composite structure. This structure allows us to utilize piezoelectric and self-biased magnetoelectric effect simultaneously. By combining these mechanisms together, a sum effect for harvesting both magnetic and vibration energy was realized under DC magnetic field free condition. The bilayer structure provides a simplified geometry that can be easily incorporated into MEMS devices. We demonstrate a hybrid synthesis method for fabrication of complex three-dimensional thin films using a cost-effective and mask-less aerosol jet deposition process. The combination of the hybrid aerosol jet process with dual phase harvester design provides the opportunity to fabricate small scale power sources required for structural health monitoring applications.

Tunable self-biased magnetoelectric response in homogenous laminates

In this study, we demonstrate self-biased magnetoelectric effect in homogenous two-phase magnetostrictive-piezoelectric laminates. Our results illustrate the method for tuning the magnitude of self-bias effect and provide understanding behind the hysteretic changes. We model this phenomenon by considering the magnetization hysteresis with shape-induced demagnetization effect. The self-biased response was found to be directly related to the nature of magnetization and can be tuned by variation in demagnetization state and the resultant differential magnetic flux distribution. These results present significant advancement toward development of AC magnetic field sensor and magnetoelectric composite based on-chip devices by eliminating the need for DC bias.