Magnetoelectric Performance Research Articles

Impact of PbZr0.5Ti0.5O3 Particle Size on the Ferroelectric and Magnetoelectric Properties of Mn0.5Zn0.5Fe2O4–PbZr0.5Ti0.5O3 Multiferroic Fluids

Herein, the impact of varying particle sizes of PbZr0.5Ti0.5O3 (PZT) powders on the ferroelectric and magnetoelectric properties of Mn0.5Zn0.5Fe2O4–PbZr0.5Ti0.5O3 multiferroic fluids is investigated. The PZT ferroelectric powders with different particle sizes (0.36, 0.28, 0.31, 0.75, 1.20 μm) are successfully prepared by altering the ball milling time. The multiferroic fluids demonstrate overall good sedimentation stability. The study finds that the dielectric constant first decreases and then increases with the reduction in particle size. The ferroelectric properties improve with the decrease in particle size and the application of a magnetic field. The multiferroic fluids with a particle size of 0.36 μm exhibit the highest polarization change (960.37%) under an electric field of 2000 Hz, 20 kV cm−1, and a magnetic field of 700 Oe. Furthermore, the magnetoelectric coupling coefficient first increases and then decreases with the reduction of the ferroelectric particle size. The multiferroic fluids with a particle size of 0.36 μm demonstrate the highest magnetoelectric coupling coefficient of 17.22 V cm−1 Oe−1 at 2000 Hz, indicating superior magnetoelectric coupling performance. These findings provide valuable insights into optimizing multiferroic fluids for applications requiring a high magnetoelectric coupling effect.

Effect of leakage current on magnetoelectric effect of 0-3 multiferroic composites based on an equivalent circuit model

In 0-3 multiferroic composites, the content of ferromagnetic particles with conductive properties significantly influences their magnetoelectric (ME) performance. The occurrence of leakage current (Lc) at high contents is a crucial factor affecting the ME properties of such composites. Establishing a rational and effective theoretical model to analyze and predict the impact of Lc on their ME performance is of paramount theoretical significance for expanding the applications of these composites. In pursuit of this objective, by introducing conduction currents, magneto-electric-mechanical/electro-magnetic-mechanical coupling factor, and resistive components, an equivalent circuit model is built to analyze the direct and converse ME effects of this composites. Meanwhile, the general analytical expressions of various effective properties are obtained. By introducing factors with combined exponential and linear decay characteristics into the piezoelectric coefficient, our theoretically calculated results quantitatively agree with experimental data. On this basis and considering the effects of displacement current and conduction current, we utilized our equivalent circuit model to calculate the ME coefficients, which showed high consistency with experimental results. Especially at high volume fractions, our computed results accurately reflected the sharp decline characteristics of the ME coefficients caused by Lc. This demonstrates the accurate and reasonable explanation provided by our model for such ME problems. In addition, the optimal set of volume fractions and magnetic fields that maximize the direct ME coefficient is obtained. This study fills a theoretical gap in the equivalent circuit method for 0-3 multiferroic composites and gives an analytical solution for the ME coefficients and provides theoretical guidance and support for the application of this composites.

Structural evolution and enhanced multiferroicity in BiFeO3-based ceramics via rare earth element co-substitution

In this study, multiple rare earth elements were introduced to modify the multiferroic properties of BiFeO3. The effects of co-substitution on the structural evolution and properties were thoroughly investigated. With increasing substitution content, the ceramics underwent a symmetry transition from R3c to Pna21 and finally to Pbnm. Co-substitution significantly enhanced the ferroelectric properties, with the highest remanent polarization of 33.14 μC/cm² observed at x = 0.10. Due to the symmetry evolution, ferromagnetism was released from the cycloidal spin structure, and the hysteresis loop gradually saturated, with the highest remanent magnetization (Mr) of 0.25 emu/g observed at x = 0.16. The concurrent improvement in ferroelectricity and ferromagnetism resulted in substantial magnetoelectric coupling performance, with αME = 3.50 mV/(cm·Oe). Moreover, direct current poling significantly induced the reverse transition from R3c to Pna21, indicating the potential for electrically controlled magnetism. This study provides a new perspective for modifying the magnetoelectric properties of BiFeO3.

Consistent c-axis orientation and reinforced magnetoelectric coupling performance in bulk BaSrCo2Fe11AlO22

Consistent c-axis orientation characteristics toward the direction of applied pressure of Y-type BaSrCo2Fe11AlO22 (BSCFAO-θ) were successfully prepared by the strategy of hot pressing. The samples’ magnetoelectric coupling performance was greatly enhanced by the strategy of hot pressing than that of the traditional solid reaction method. The magnetoelectric current of BSCFAO-θ (θ = 0°) (12.06 μA/m2) was nearly 5 times higher than BSCFAO-SS (2.24 μA/m2). The magnetoelectric polarization of BSCFAO-θ (θ = 0°) (32.82 μC/m2) was nearly 4 times higher than that of BSCFAO-SS (8.31 μC/m2). The magnetoelectric coupling coefficients of BSCFAO-θ (θ = 0°) (1880 ps/m) were nearly 4 times higher than those of BSCFAO-SS (404 ps/m). The enhancement of magnetoelectric polarization of BSCFAO-θ (θ = 0°) can be attributed to the uniform c-axis orientation, which reinforced magnetoelectric polarization compared with none orientation that eliminated the magnetoelectric polarization on grain boundaries. The magnetoelectric coupling performance of BSCFAO-θ presented a gradually decreasing trend with the angle changing from 0° to 90° for the changing of orientation. Compared with traditional solid reaction methods, the strategy of hot pressing inhibits grain growth and increases grain boundaries, thus facilitating the enhancement of grain boundaries’ resistivity, and the electrical resistivity of BSCFAO-θ (3.08 × 1010 Ω cm) was nearly 10 000 times higher than that of BSCFAO-SS (2.5 × 106 Ω cm), which also benefits the magnetoelectric polarization performance of BSCFAO-θ. Therefore, the hot-pressing strategy can contribute to the forming of oriented ceramics and enhance the grain boundaries’ resistivity to improve magnetoelectric coupling performance.

Optimizing energy storage and magnetoelectric performance through core–shell engineering: A study on Ni0.5Co0.5Fe2O4-BaTiO3 multiferroic composite materials

In this report, we have synthesized Ni0.5Co0.5Fe2O4 (NCFO) and BaTiO3 (BTO) core–shell (12 % NCFO − 88 %BTO) multiferroic nanopowder by hydrothermal method and sol–gel method, respectively. The structural, morphological, ferroelectric, and magnetoelectric properties of the as- prepared sample was investigated in detail. X-ray diffraction results revealed that no secondary phase is obtained. As investigated from the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis, the grains are almost spherical, which depicts the core–shell like morphology and the presence of all the constituent elements in the prepared sample. FTIR analysis gives information about the formation of two individual phases and the different chemical compositions present in the sample. The prepared core–shell composite exhibits a notable energy storage density W (38.25 mJ/cm3), accompanied by a slightly lower energy storage efficiency η (46.50 %) and energy loss density Wrec (17.78 mJ/cm3). Magnetic characterization revealed that the sample shows lower saturation magnetization (1.33 emu/g) with coercivity (430 Oe) and magneto-crystalline anisotropy (595.7 erg/g). A moderate magnetoelectric coefficient of 18.34 mV/cm*Oe is observed on the higher field side, surpassing the value on the lower field side 32.62 mV/cm*Oe. Anisotropy in the system leads to varying magnetoelectric coefficients in different directions. These findings provide valuable insights for enhancing the magnetoelectric response in core–shell multiferroic composites.

The effect of mechanical energy loss and bonding layer on magnetoelectric performance for metglas/PVDF laminated composites

The effect of mechanical energy loss and bonding layer on magnetoelectric performance for metglas/PVDF laminated composites

Tunable synthesis of magnetoelectric CoFe2O4-BaTiO3 core-shell nanowires.

A template-assisted synthesis approach was employed to tune the structure and properties of CoFe2O4-BaTiO3 core-shell magnetoelectric nanowires. By adjusting the composition of the nanowires, we achieved control over the magnetic anisotropy in the CoFe2O4 core phase. This work highlights the potential for enhanced magnetic anisotropy to improve magnetoelectric performance.

Enhanced magnetoelectric coupling performance in CoFe2O4 @BaTiO3 multiferroic liquid by tuning the CoFe2O4 morphology

Multiferroic materials are identified as a newly emerging area of research because of their obvious magnetoelectric effects between ferroelectric and ferromagnetic orders. This paper uses the ball milling method to prepare CoFe2O4 @BaTiO3 (CFO@BTO) multiferroic liquids with different CoFe2O4 (CFO) particle morphologies. The settling stability and magnetoelectric properties of the CFO@BTO multiferroic liquids with different CFO particle morphologies have been systematically studied. XRD analysis confirmed that the crystal structure of the powders was consistent with that of standard cards, and the CFO powders exhibited irregular spherical shapes, well-dispersed rectangular shapes, and uniform nanowires. TEM images revealed a core-shell structure of the formed particles. The study found that as the CFO particle morphology changed from spherical to rectangular and then to nanowire, both the residual magnetization intensity (Mr) and saturation magnetization intensity (Ms) of both CFO powder and CFO@BTO composite powder increased gradually. The settling rate of the multiferroic liquids with spherical CFO morphology was observed to be 4.6% with good settling stability after resting for 48 h. The dielectric constant and dielectric loss showed similar trends in the presence and absence of magnetic fields. With the change in CFO particle morphology, the maximum polarization strength (Pmax), residual polarization strength (Pr), and coercivity field strength (Ec) of the multiferroic liquids gradually increased. The magnetoelectric coupling coefficient of the multiferroic liquids was found to be the largest when the CFO morphology was rectangular, measuring 23.93 V/(cm·Oe). The study provides insights into improving the magnetoelectric coupling effect of multiferroic materials and opens up new possibilities for further research in this area.

Correlation between meso-structures and magnetoelectric properties in 0-3 magnetoelectric composites

The quantitative characterization of macroscopic properties of 0-3 polymer-based magnetoelectric (ME) composites is the basis of their application, and the meso-structure is the source that affects their macroscopic properties. In this study, theoretical models consistent with the meso-structures of the composites are developed to address scenarios involving random, chain, and agglomeration particle distributions. The focus is on investigating the nonlinear mechanical behavior of multi-field coupling. The validity and rationality of the theoretical model are confirmed by comparing the theoretical results with existing experimental data. Based on this, the distribution characteristics of elastic field, electric field and magnetic field of 0-3 polymer-based ME composites with different particle arrangements are analyzed. Additionally, the influence of several factors on the ME properties, such as magnetic field strength and direction, particle proportion and frequency, is discussed. The results indicate that the ME performance is optimized when the direction of the densest chain row of particles aligns with the direction of the applied magnetic field. Furthermore, the phenomenon of current leakage is examined when the direction of the chain row of ferromagnetic particles coincides with the direction of polarization. To mitigate this leakage effect, a solution is proposed by adding thin layers of piezoelectric polymer to the surface of the composite, resulting in a 62.6% increase in ME performance. The research findings reveal the response mechanisms and essence of 0-3 polymer-based ME composites under applied magnetic fields, establishing a connection between meso-structures and macro properties. This provides guidance for the design and optimization of mesomorphic structures and performance, and serves as a foundation for the design, fabrication, and development of a new generation of ME devices.

PVDF based flexible magnetoelectric composites for capacitive energy storage, hybrid mechanical energy harvesting and self-powered magnetic field detection

Here we develop YFeO3-poly(vinylidene fluoride) (YFO-PVDF) based composite systems (with varied concentration of YFO in PVDF) and explore their multifunctional applicability including dielectric, piezoelectric, capacitive energy storage, mechanical energy harvesting, and magnetoelectric performances. The 5 wt% YFO loaded PVDF (5 YF) film has exhibited the highest polar phase percentage of ∼85%. On the other hand, the study of energy storage performance has shown the highest energy storage density for 3 wt% YFO loaded PVDF (3 YF) film. Owing to its highest polar phase and space charge polarization, the 5 YF film has shown the highest mechanical energy harvesting performance with open circuit voltages of ∼10 and 74 V and power densities of ∼2 and 47 μW/cm2 from the corresponding piezoelectric and piezo-tribo hybrid devices, respectively. The fabricated composite films have also shown good magnetoelectric (ME) properties with an ME coupling coefficient (α33) of ∼5.2 mV cm−1 Oe−1 (at 1 kHz frequency and 0.8 kOe applied DC field) for the poled 5 YF film. The application of an external magnetic field has shown the ability to tune the mechanical energy harvesting performances of both the piezoelectric and piezo-tribo hybrid devices which suggests their future application in self-powered magnetic field sensing.

Grain size and piezoelectric effect on magnetoelectric coupling in BFO/PZT perovskite-perovskite composites

Magnetoelectric multiferroics are provoking much research activity for their potential applications in novel multifunctional devices. Compared with single-phase multiferroics, magnetoelectric composites have competitive advantages. The magnetoelectric coupling of composites is heavily influenced by composition and grain size. We prepared BFO/PZT composites with separate phases via the solid-state sintering method. We show that equal molar ratio composition has a better magnetoelectric coupling response than other compositions. The composites with nano bismuth ferrite have better magnetoelectric coupling performance, and these with both nano grain sizes present the highest magnetoelectric voltage coefficients (αE = 16.9 mV cm−1 Oe−1). The strain-mediated mechanism was confirmed via a comparison between strain response and polarization of nano/micro type composites with the composition of 3:7. We found that the magnetoelectric voltage coefficient αE positively correlates with strain response instead of polarization in BFO/PZT composites, which provides experimental evidence for the strain-mediated ME composite theory.

Magnetic, mechanical, electrical properties and coupling effects of particle reinforced piezoelectric polymer matrix composites

The 0-3 polymer-based magnetoelectric (ME) composites have the advantages of easy preparation, low cost, good flexibility, environmental friendliness and biological affinity, etc., and have a wide range of applications prospect in the biomedical field, such as the biological microelectronics, nanomedicine technology treatment, bone tissue healing and so on. The ME performance of this composite is jointly contributed by the properties of its component and microstructure. In this work, considering the impact of interphase effect, and the relationship between the effective properties of 0-3 ME composites and its microstructure is established, and the expressions of the Young's modulus, permeability, dielectric coefficient, piezoelectric coefficient, piezomagnetic coefficient and ME coefficient are obtained respectively. The effects of interphase properties and particle sizes on the effective properties of ME composites are discussed. By comparison, our theoretical results are in good agreement with experimental data. Then the influence of some factors on its effective performance is discussed. The results show that the effective properties of 0-3 ME composites are strongly dependent on the volume fraction ratio and size of the particles, the applied magnetic field. There is an optimal volume ratio and magnetic field to maximize ∂ α E 33 /∂ H 3 .

Multiferroic nitride perovskites with giant polarizations and large magnetic moments

Multiferroics with coupling between ferroelectricity and magnetism have been pursued for decades. However, their magnetoelectric performances remain limited due to the common trade-off between ferroelectricity and magnetism. Here, a family of nitride perovskites is proposed as multiferroics with prominent physical properties and nontrivial mechanisms. Taking GdWN$_3$ as a prototype, our first-principles calculations found that its perovskite phases own large polarizations (e.g. $111.3$ $\mu$C/cm$^2$ for the $R3c$ phase) and a magnetic moment $7$ $\mu_{\rm B}$/Gd$^{3+}$. More interestingly, its ferroelectric origin is multiple, with significant contributions from both Gd$^{3+}$ and W$^{6+}$ ions, different from its sister member LaWN$_3$ in which the ferroelectricity almost arises from W$^{6+}$ ions only. With decreasing size of rare earth ions, the A site ions would contribute more and more to the ferroelectric instability. Considering that small rare earth ions can be primary origins of both proper ferroelectricity and magnetism in nitride perovskites, our work provides a route to pursuit more multiferroics with unconventional mechanisms and optimal performances.

Three-dimensional finite element simulation of magnetic-mechanical-electrical coupling in layered cylindrical multiferroic structures

The excellent magnetoelectric (ME) performance of multiferroic structures under room temperature has inspired a wide range of applications in smart devices like energy collectors, ME transducers, neo-antennas, etc. Starting from the constitutive equations of ferroelectric and ferromagnetic materials, a three-dimensional (3D) finite element simulation model was set up to investigate the ME behaviors of the cylindrical structures consisting of Terfenol-D and lead zirconate titanate (PZT). Then the solid mechanical module, electrostatic module and the magnetic module are coupled to calculate the mechanical, electrical and magnetic properties of the components and the structures. The calculated ME coefficients were in good agreement with the experimental data. The results show that P/T and T/P structures reach the maximum of ME coefficients at different bias magnetic fields, approximately 2.5×104 A/m for P/T structure and 4.8×104 A/m for T/P structure. The maximum value of αE31 in the P/T structure is twice that of T/P structure. Moreover, the distribution of magnetic, mechanical, and electrical fields of the composites are also analyzed. The results show that the magnetization of the ferromagnetic material exhibits a non-uniform distribution at low magnetic field, the stress concentration occurs at the Terfenol-D and PZT interface, and the electric potential of piezoelectric material is non-uniform in the plane. Finally, the influence of the interface characteristics on the ME effect is also studied. It is found that, the thicker the interface and the lower the Young's modulus, then the smaller the corresponding ME coefficient for the P/T structure.

Study on FeSiAl magnetic powder core coated with nano-Y2O3 and its influence on magnetic properties

The microstructure and magnetic properties of the FeSiAl /phosphoric acid/nano-Y2O3/kaolin soft magnetic composites were investigated in this article. The morphology and structure were characterized by SEM, EDS, XRD, DSC, and XPS. The surface of FeSiAl powder particles was densely and uniformly coated with a phosphoric acid/nano-Y2O3/kaolin insulating coating. It was discovered that nano-Y2O3 played a dominant role in the coating process. Using a precision magnetic analyzer and lossy power tester, the effective permeability, quality factor, DC bias performance, and the core loss of the FeSiAl/phosphoric acid/nano-Y2O3/kaolin SMCs after pressing and annealing were computed and examined. The results show that nano-Y2O3 can improve the quality factor and DC bias performance of the powder core, but leads to a reduction in magnetic permeability and the core loss is also a little high. This behavior may be caused by the competition mechanism: nano-Y2O3 lowers the magnetic coupling between FeSiAl particles, resulting in a decrease in permeability and an increase in the core loss. When the content of nano-Y2O3 is 5 wt%, the comprehensive magnetoelectric performance is good (ue=21.04, at f =100 kHz; Pcv = 1555.13 mW/cm3, at f = 50 kHz; Q = 150.25, at f = 70 kHz; at Bm = 1000 Gs). The effects of nano-Y2O3 coating on the permeability and the loss of FeSiAl SMCs will be a major focus of future research and development.

Optimal magnetoelectric coupling performance of Terfenol-D/PZT composites in resonance state under bias magnetic field

Laminated magnetoelectric (ME) composites with various thickness ratios were optimized, fabricated and experimentally investigated in this work. The Terfenal-D/PZT specimens with optimal thickness ratio between the magnetostrictive phase and piezoelectric phase, and two other values were tested for their ME coupling performance. The coupling voltage output increases linearly with the increase of DC bias magnetic field. The ME voltage coefficient increases more than 100 times in the resonance state for the optimal laminate. The DC bias magnetic field affects the ME voltage coefficient significantly, and also has little effect on the resonant frequency. The strength of AC magnetic field also slightly affects the ME voltage coefficient in resonance state, but does not affect the resonant state under which the same DC magnetic field is required. The experimental results can help understand the coupling performance of ME composite under bias magnetic field and prompt the application of ME devices.

Computer Simulation of Magnetoelectric Antenna and Performance Comparison With Micro-Loop

Electromagnetic radiation can be produced using functional materials such as magnetoelectric (ME) composites, in which the magnetoelasticity and piezoelasticity of material are involved. The mechanical nature of the vibrations is used to miniaturize the ME antenna to micro-scale size. The antenna performance evaluation requires a multiphysics analysis of the structure. An ME antenna design and simulation is detailed using the finite element method (FEM) in COMSOL Multiphysics® in which the structural mechanics, electrostatics, and magnetic field physics are coupled together to address the simulation needs. An antenna size of 250 μm × 50 μm × 1 μm is simulated within a static magnetic bias field of 20 mT. The nonlinear isotropic model is used for magnetostrictive material definition in which the prestress is defined by the magnetic bias. The model is linearized for radio frequency (RF) simulations to account for the AC simulation. The antenna farfield radiation pattern and the gain are computed using finite difference time domain (FDTD) by incorporating the extracted nearfield of the ME antenna in COMSOL. The simulated antenna impedance, radiation pattern and antenna gain are compared to an equivalent micro-loop magnetic antenna. In addition, electromagnetic computations are used to evaluate the coupling performance between the ME antenna and a larger loop antenna over a distance up to 20 mm in free space and biomedical tissues to address the potential of using ME antenna in medical implants for wireless communication and wireless power transfer.

Low magnetic-field induced high temperature dynamic magnetoelectric coupling performances in Z-type Sr3Co2Fe24O41

Magnetic-field induced dynamic magnetoelectric coupling effects and polarization performance of Z-type Sr3Co2Fe24O41 (SCFO) ceramic has been investigated. Results found that SCFO’s transverse tapered magnetic structure can induce electric polarization, and its electric polarization direction will not change under external magnetic effects. First-order dynamic magnetoelectric coupling coefficient (α) and second-order dynamic magnetoelectric coupling coefficient (β) of SCFO exhibited strong response main in magnetic structural phase transition region. The magnetoelectric structural phase transition position appeared in low magnetic field, and the magnetic moment vector and its corresponding electric polarization vector of SCFO exhibited the most unstable state near its equilibrium position, which is beneficial for inducing strong dynamic magnetoelectric coupling response. When the applied magnetic fields to SCFO increased, the magnetic moment stability near the equilibrium position increased, and the dynamic magnetoelectric coupling response decreased. Results showed that the dynamic magnetoelectric coupling response of SCFO can bear T 1 = 370 K high temperature. The dynamic magnetoelectric coupling response induced by low magnetic fields in SCFO contributes to its actual application in next generation magnetoelectric information storage devices.

On the magnetoelectric performance of multiferroic particulate composite materials

In the current work, quantitative analysis of magnetoelectric particulate composite material system explicated the main mechanisms responsible for the below-optimal performance of this class of materials. We considered compliant particulate composite materials, with constituents relevant to technological and scientific interest, leading to 0–3 Terfenol-D/PVDF–TrFE composite samples. To this objective, thick Terfenol-D/PVDF–TrFE films (10–15 µm) were fabricated and analyzed for chemical, mechanical, and magnetic properties to demonstrate their suitability for energy applications in harsh environmental conditions. The vigorous experimental characterization of the composite exemplified the multifunctional properties, quantifying the interrelationship between the composition and performance. We observed that the addition of magnetic particles to the electroactive copolymer matrix resulted in improvement in the mechanical and electrical properties since the particles acted as pinning sites, hindering the deformation of the chains and enhancing polarization. The effective modulus model was amended to account for the crystallization-induced change in material stiffness. We also measured and computed the magnetic particles motion to explicate the detrimental effect of mobility and migration on the overall magnetoelectric coupling performance of the composite. Thereby, we derived an analytical model based on the magnetic force due to the co-presence of alternating and constant magnetic fields, and the viscous drag force due to the viscoelastic properties of the electroactive copolymer matrix. We demonstrated that the mobility of the particles plays a crucial role in the short and long term performance of magnetoelectric coupling in multiferroic particulate composites, uncovering the underpinnings of the dichotomy in performance between experimentally measured and analytically predicted coupling coefficients, thus allowing for the proposal of new approaches to realize the scientific potential of magnetoelectric particulate composites in energy applications.

Spin-Dependent Transport at 2D Solids: From Nonmagnetic Layers to Ferromagnetic van der Waals Structures

Spintronics is a promising alternative to the conventional silicon transistor-based electronics that are gradually approaching their physical limitations. Ultrathin two-dimensional van der Waals (vdW) materials (2D materials) with controllable spin degrees of freedom are recognized as extremely promising spintronic materials in architectures for the post-Moore era. In this Perspective, we review recent progress on spin-dependent transport behaviors (SDTBs) confined at the 2D scale, which are the mainstream paradigms for spintronic devices. We first present the mechanism and the key factors of SDTBs in 2D nonmagnetic materials-based hybrid devices. Then, some chemical modulation strategies for inducing short-range magnetic order and magneto-electric performance into 2D nonmagnetic materials are discussed. Furthermore, we concentrate on introducing intriguing SDTBs in 2D long-range ferromagnetic materials-based vdW devices. Finally, we highlight the current challenges in the study of spin-dependent transport of 2D modified materials and 2D material-based spintronic devices, in the hope of accelerating their applications.