Magnetoelectric Coupling Response Research Articles

Magnetoelectric coupling response of novel mullite coated Ni–Zn–Cu-ferrite nanocomposite

Novel multiferroic nanocomposite fabricated by Ni–Zn–Cu-ferrite (NZCF)-mullite is reported in this article. The crystallographic phases are confirmed by X-ray diffraction. The static magnetic properties are measured for both bare NZCF and mullite encapsulated NZCF nanocomposite which show the successful retention of the magnetic behaviors of the nanocomposites even at higher annealing temperature of 1200 °C. The dielectric response is estimated and high value of dielectric constant (∼210.7 at 100 Hz) is observed for the mullite encapsulated NZCF nanocomposite due to the formation of interfacial polarization in the nanocomposite. The temperature dependent dielectric response suggests the presence of dielectric polarization in the NZCF-mullite nanocomposite. Magnetocapacitance (MC) study of the NZCF-mullite nanocomposite sample is observed at room temperature (RT). The observed MC and its variation with magnetic field confirm the presence of strong interactions between the magnetic and ferroelectric order parameters in the nanocomposite sample.

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.

Nonlinear Stress dependent Resonant Studies on Press-fit ME Composites

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

Magnetoelectric coupling coefficient in multiferroic capacitors: Fact vs Artifacts

Multiferroic materials are characterized by their magnetoelectric coupling coefficient, which can be obtained using a lock-in amplifier by measuring the voltage developed across a multiferroic capacitor in a time-variable magnetic field, Hac cos(ωt), where Hac and ω are the amplitude and frequency of the applied magnetic field. The measurement method, despite its simplicity, is subject to various parasitic effects, such as magnetic induction, which leads to significant over-estimation of the actual magnetoelectric response. This article outlines the measurement theory for a multiferroic capacitor using the lock-in technique. It is demonstrated that the inductive contribution has linear proportionality with Hac, ω, and Hacω. It is shown that the true magnetoelectric coupling response is retrieved from the real component of the lock-in signal. Using a polymer-nanoparticle multiferroic composite, the internal consistency of the proposed measurement method is experimentally demonstrated, and it is shown that the actual multiferroic signal can be retrieved using the lock-in technique by removing the magnetic induction contribution from the signal. It is observed that the magnetoelectric voltage shows only a linear dependence with Hac, a saturating behavior with ω, and Hacω. Furthermore, a measurement protocol for reliable reporting of magnetoelectric coupling coefficient has been provided.

Strain mediated magnetoelectric coupling response in Ba0.85Ca0.15Ti0.9Zr0.1O3–CoFe1.95Mg0.05O4 particulate multiferroic composites

Strain mediated magnetoelectric coupling response in Ba0.85Ca0.15Ti0.9Zr0.1O3–CoFe1.95Mg0.05O4 particulate multiferroic composites

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.

Enhanced magnetoelectric coupling response in hot pressed BiFeO3 and polymer composite films: Effect of magnetic field on grain boundary and grain resistance

We report the effect of grain boundary resistance (GBR) and grain resistance (GR) on the magnetoelectric coupling in the multiferroic composite thick films of BiFeO3 (BFO) nanocrystalline powder and poly vinylidene-fluoride (PVDF) polymer. These composite thick films of thickness ∼ 0.2 mm were prepared via hot pressing with the weight ratio of BFO powder and PVDF polymer as 70:30 (abbreviated as BFO70), 60:40 (abbreviated as BFO60), 50:50 (abbreviated as BFO50) and 40:60 (abbreviated as BFO40), respectively. Impendence investigations (Cole-Cole plots) of these thick films demonstrate that the GBR is significantly changed on the application of magnetic field (8 kOe) in comparison to the GR. Our results indicate that the GBR plays an important role in strengthening of magnetoelectric (ME) effect in BFO-PVDF system. In addition, the ME coupling study indicates that the BFO50 sample shows better results (α33 ∼ 2.7 mV/cm-Oe) and may be suitable for device and sensor applications.

Structural, magnetic, magneto-dielectric and magneto-electric properties of (1-x) Ba0.85Ca0.15Ti0.90Zr0.10O3 – (x) CoFe2O4 lead-free multiferroic composites sintered at higher temperature

Here in this article synthesis of lead-free magnetoelectric composites (1-x) Ba0.85Ca0.15 Ti0.9Zr0.1)O3 - xCoFe2O3 (BCTZ-CFO, x = 0.4, 0.5, and 0.6) is reported. Structural, magnetic, dielectric, magnetodielectric and magnetoelectric properties of lead-free BCTZ-CFO composites sintered at higher sintering temperature have been systematically investigated. The piezoelectric (ferroelectric) phase has been synthesized using the sol–gel route, while Metallo-organic decomposition (MOD) route was employed to prepare piezomagnetic (ferrite) phase. The structural and microstructural properties were studied using X-Ray diffraction and Scanning electron Microscope respectively acknowledged the presence of two distinct phases as ferrite and ferroelectric in composite samples. The dense microstructure and larger average grain size were observed for samples with higher ferrite phase content. Long-range magnetic order was observed under magnetic study for all-composites. The magnetic properties enhanced for composites prepared with higher ferrite phase content. Dielectric properties were studied at room temperature and enhanced dielectric constant has been observed for samples with higher ferroelectric phase content, while minimum dielectric loss was observed for sample with 50/50 ferrite/ferroelectric phase composition. The magnetodielectric response has been also investigated for all ME composites. Leakage current characterization has been also discussed at and above the room temperature. The magneto-electric coupling response was measured of all composites. The higher value of magneto-electric coupling coefficient has been observed for 0.5BCTZ-0.5CFO composite due to maximum possible ferrite-ferroelectric hetero-structure phase contact area.

Relaxor (Pb0.7Bi0.3)(Mg0.231Nb0.462Fe0.3)O3 electronic compound for magnetoelectric field sensor applications

A solid solution between relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) and multiferroic BiFeO3 (BFO) has been synthesized by a solid-state chemical reaction route. The comprehensive x-ray diffraction studies of (1 − x)PbMg1/3Nb2/3O3–xBiFeO3 [(1 − x)PMN–xBFO] confirm the realization of stable and orthorhombic crystal systems. From the dielectric study, relaxor behavior has been observed, which is corroborated by a broadened peak and diffusive phase transition. The magnetoelectric (ME) properties have been explored through P–E loop, M–H loop, and magnetoelectric coefficient analyses. The simultaneous occurrence of polarization and magnetization reveals the ME coupling response of the PMN–BFO compounds. Excellent values of PS = 15.94 μc/cm2, Pr = 7.68 μc/cm2, MS = 12.96 emu/g, Mr = 1.25 emu/g, and ME coefficient value of 220 mV/cm Oe for x = 0.3 are obtained, which is helpful for magnetoelectric field sensor applications. To ascertain its sensing capability, a prototype has been developed, and the sensing behavior of the device has been established by placing it near a designed helical coil electromagnetic field generator structure.

Influence of Pr3+ and Lu3+ co-doping on the magnetoelectric coupling response in BiFeO3 mutiferroic ceramics

Perovskite-type bismuth ferrite (BiFeO3) multiferroic material is being considered as a potential candidate for magnetoelectric coupling and field-controlled multi-state memory applications. We report the Pr3+ and Lu3+ co-doping effect on the magnetoelectric coupling in BiFeO3 ceramics. In this study, Bi0.94Pr0.06FeO3 (BPO), Bi0.94Lu0.06FeO3 (BLO), and Bi0.94Pr0.03Lu0.03FeO3 (BPLO) ceramics were synthesized by conventional solid-state ceramic synthesis technique. The BPO sample displayed higher saturation magnetization as compared to BLO and BPLO samples which may be due to canting of spin cycloid of BFO and also due to the discrepancy between the antiparallel sublattice of Fe3+/Fe2+, the value of ferroelectric polarization of the BPO sample was found to be better than BLO and BPLO samples. However, the magnetocapacitance (MC) of the BPLO sample is found to be MC ~ 2.3% which is higher than that of BLO (MC ~ 1.4%) and BPO (MC ~ 1.7%) samples. In addition, the enhanced value of magnetoelectric coupling coefficient (αE) has been obtained for the BPLO sample. Overall, our results indicate that BPLO sample displays interesting magnetoelectric response for device applications.

Magnetoelectric composite films of La0.67Sr0.33MnO3 and Fe-substituted Bi4Ti3O12 fabricated by chemical solution deposition

Magnetoelectric composite layered films of La0.67Sr0.33MnO3 (LSMO) and Fe-substituted Bi4Ti3O12 (Bi4Ti3-xFexO12, BiTFx, x = 0.05, 0.10, 0.15 and 0.20) were fabricated on a LaNiO3-buffered silicon substrate by chemical solution deposition method. The LaNiO3 layer with c-axis orientation can not only induce the oriented growth of the overlaying LSMO and BiTFx layers, but also can act as an electrode material for electric measurements. The Fe-substituted content has a significant effect on the surface morphology of BiTFx phase, and leakage, dielectric and ferroelectric properties of the BiTFx/LSMO films. The BiTF0.10/LSMO composite film exhibits an improved leakage performance, the highest dielectric constant and the best ferroelectric properties. Furthermore, an interesting finding is that a weak ferromagnetism is present in the BiTF0.10 phase. The first-principle calculations suggest that the spin-resolved total density of states for BiTF0.10 are asymmetric, which can induce spin splitting and magnetic moments. The BiTF0.10/LSMO film also exhibits excellent magnetoelectric coupling performance, and its magnetoelectric coupling response is sensitive to AC magnetic frequency. The highest magnetoelectric coupling voltage coefficient can reach up to 47.5 V/cm·Oe without the presence of DC bias magnetic field.

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.

Room temperature multiferroic properties of rare-earth-substituted Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 ceramics

Polycrystalline rare-earth-substituted Bi5Ti3Fe0.7Co0.3O15 (BReFCT (Re = La, Nd and Ho)) ceramics were prepared by conventional solid-state reaction. The main four-layered Aurivillius structure was confirmed in the as-prepared ceramics by X-ray diffraction and Raman spectra analysis though a small amount of secondary phase consisting of magnetic Co and Fe elements was detected by SEM/EDS. The observed ferromagnetic behavior and magnetoelectric coupling response were attributed to the main Aurivillius phase. A maximum ME coefficient of 31.58 mVcm−1Oe−1 was achieved in BLaFCT ceramics. The magnetic and magnetoelectric coupling properties in BReFCT ceramics were discussed based on the radius difference of the rare earth ions and the induced distorted lattice structure. The enhanced magnetoelectric properties of the BReFCT ceramics are promising for novel magnetoelectric device applications.

Multiferroic magnetoelectric coupling effect of bilayer La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3 complex thin film

Magnetoelectric (ME) coupling effect of 2-2-type ferromagnetic/ferroelectric bi-layer multiferroic epitaxial thin film (La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3, LSMO/PZT) on SrRuO3 (SRO) substrate is investigated systematically by using Landau–Ginzburg–Devonshire (LGD) thermodynamic theory and modified constitutive equations. The calculating results clarify the detail relationships between ME coupling response and the residual strain, the volume fraction of constituent phases, the interface coupling coefficients, the magnetic field and the temperature. It also shows that improved ME coupling response can be modulated by these parameters. External magnetic fields (H1) induced ME coupling effect could be enhanced around Curie Temperature (Tc) of ferromagnetic phase and ME voltage coefficient (αE31) approaches a maximum at H1∼4.5 kOe near Tc. The remarkable variations of ME coupling response can be used to provide useful guidelines on the design of multifunctional devices.

Magnetoelectric polymer nanocomposite for flexible electronics

This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites.

Magnetoelectric coupling effect in transition metal modified polycrystalline BiFeO3 thin films

Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO3 (BFO) thin films have been deposited on Pt/TiO2/SiO2/Si substrate successfully through pulsed laser deposition (PLD) technique. Piezoelectric, leakage current and temperature dependent dielectric and magnetic behaviour were investigated for the films. Typical “butterfly-shaped” loop were observed in BSFCO films with an effective piezoelectric constant (d33) ~94pm/V at 0.6MV/cm. High dielectric constant ~900 and low dielectric loss ~0.25 were observed at room temperature. M–H loops have shown relatively high saturation magnetization ~35emu/cm3 at a maximum field of H ~20kOe. Enhanced magnetoelectric coupling response is observed under applied magnetic field. The multiferroic, piezoelectric, leakage current behaviours were explored. Such studies should be helpful in designing multiferroic materials based on BSFCO films.

Polarization conversion of reflected electromagnetic wave from topological insulator

Based on the special electromagnetic properties of a 3D strong topological insulator (TI), we discuss, theoretically, the reflection of electromagnetic wave at the interface between a dielectric and a TI, and focus on the polarization conversion between the incident field and reflected field. Two cases, linear polarization and elliptical polarization at oblique incidence are considered. We derive the conditions required for the complete polarization conversion from incident s polarization into reflected p polarization, and vice versa. Furthermore, elliptical polarization incidence also can be modulated to linear or circular polarization after reflection, under special conditions, and the corresponding reflectivity can approach 1. All these special polarization behaviors originate from the intrinsic topological magnetoelectric coupling response in TI. This work provides promising applications of TIs on polarized devices and the polarization splitters.

Ferroelectric, Ferromagnetic, and Magnetoelectric Properties of Multiferroic Ni0.5Zn0.5Fe2O4–BaTiO3 Composite Ceramics

Lead-free multiferroic composite ceramics xNi0.5Zn0.5Fe2O4–(1 − x)BaTiO3 (x = 0.2, 0.5, 0.8) with a 0–3-type connection structure have been prepared by a traditional ceramic process. The cubic spinel Ni0.5Zn0.5Fe2O4 phase and the tetragonal perovskite BaTiO3 phase were confirmed by x-ray diffraction. The effect of Ni0.5Zn0.5Fe2O4 ferrite content on ferroelectric and ferromagnetic behavior, and the magnetoelectric coupling effect of the composite ceramics is discussed. With increasing Ni0.5Zn0.5Fe2O4 ferrite content, the saturation magnetization of the composite ceramic increased and the saturation polarization decreased. The magnetoelectric coupling response voltage was observed to decrease rapidly for samples with x = 0.2, then 0.5, then 0.8. The highest magnetoelectric coupling response voltage, measured for 0.2Ni0.5Zn0.5Fe2O4–0.8BaTiO3, was 150 μV, which corresponds to a maximum magnetoelectric coupling voltage coefficient of 109 μV/cm Oe. When x = 0.5, the maximum magnetoelectric response voltage is only 8 μV, and when x = 0.8, no magnetoelectric response voltage is detected because of very large leakage current of the 0.8Ni0.5Zn0.5Fe2O4–0.2BaTiO3 composite ceramic.

Multiferroic properties of Bi 3.15Nd 0.85Ti 3O 12–CoFe 2O 4 bilayer films derived by a sol–gel processing

Multiferroic Bi 3.15Nd 0.85Ti 3O 12 (BNT)–CoFe 2O 4 (CFO) bilayer films with different preferential orientations and thickness fractions for the BNT layer were prepared on Pt/Ti/SiO 2/Si substrate by a sol–gel processing. The experimental results showed that the bilayer films with preferentially a-axis oriented and thicker BNT layer have better ferroelectric properties. The magnetoelectric coupling response is weak when the degree of a-axis orientation of the BNT layer is low or the leakage current is high, while it is mainly controlled by the thickness fraction in other cases.

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. An electric polarization is induced by a weak ac magnetic field oscillating in the presence of a dc bias field, and/or a magnetization polarization appears upon applying an electric field. So far, three kinds of bulk magnetoelectric composites have been investigated in experimental and theoretical, i.e., composites of (a) ferrite and piezoelectric ceramics (e.g., lead zirconate titanate), (b) magnetic metals/alloys (e.g., Terfenol-D and Metglas) and piezoelectric ceramics, and (c) Terfenol-D and piezoelectric ceramics and polymer. The elastic coupling interaction between the magnetostrictive phase and piezoelectric phase leads to giant magnetoelectric response of these magnetoelectric composites. For example, a Metglas/lead zirconate titanate fiber laminate has been found to exhibit the highest magnetoelectric coefficient, and in the vicinity of resonance, its magnetoelectric voltage coefficient as high as 102V∕cmOe orders has been achieved, which exceeds the magnetoelectric response of single-phase compounds by many orders of magnitude. Of interest, motivated by on-chip integration in microelectronic devices, nanostructured composites of ferroelectric and magnetic oxides have recently been deposited in a film-on substrate geometry. The coupling interaction between nanosized ferroelectric and magnetic oxides is also responsible for the magnetoelectric effect in the nanostructures as was the case in those bulk composites. The availability of high-quality nanostructured composites makes it easier to tailor their properties through epitaxial strain, atomic-level engineering of chemistry, and interfacial coupling. In this review, we discuss these bulk and nanostructured magnetoelectric composites both in experimental and theoretical. From application viewpoint, microwave devices, sensors, transducers, and heterogeneous read/write devices are among the suggested technical implementations of the magnetoelectric composites. The review concludes with an outlook on the exciting future possibilities and scientific challenges in the field of multiferroic magnetoelectric composites.