Magnetoelectric Behavior Research Articles

The effect of interface strains induced by various ferroelectric top layers on the magnetoelectric behavior for bilayer heterostructure

The effect of interface strains induced by various ferroelectric top layers on the magnetoelectric behavior for bilayer heterostructure

Investigating the multiferroic properties within triphasic systems to comprehend the mechanisms of water splitting

In the present study, a triphasic-based system was prepared using constituents such as Lanthanum Calcium Manganite (LCM), Cobalt Ferrite (CF), and Barium Titanate (BT) in different proportions. The composition (1-x)LCM: x(0.7CF-0.3BT), where x = 0, 0.1, 0.2, 0.3, and 1, was employed to produce the triphasic system-based materials using a solid-state reaction technique. X-ray diffraction results confirmed the development of the triphasic phase in the composites through the JCPDS card number of the major peaks. The average crystallite size calculated from XRD data was found to vary with increasing 0.7CF-0.3BT concentration in LCM. FTIR spectroscopy indicates alterations in the main peaks with an increase in content of 0.7CF-0.3BT, suggesting the formation of triphasic composites. The upward trend in dielectric permittivity suggests the successful occurrence of Maxwell-Wagner polarization, indicating relaxor behavior at lower frequency values. Impedance spectroscopy reveals dielectric relaxation and the contribution of charge carriers in triphasic composites, along with the impact of grain and grain boundaries. Magnetization analysis at room temperature approves an increase in saturation magnetization in composites i.e., 0.7LCM-0.3(0.7CF-0.3BT) triphasic material exhibiting a maximum saturation magnetization of 13.04 emu/g. Magnetoelectric behaviour is observed in triphasic materials at different AC magnetic fields. The 0.9LCM-0.1(0.7CF-0.3BT) triphasic hydroelectric cell achieved a peak current of 1.29 mA and showed enhanced stability over time. Its I-V characteristics revealed a short-circuit current of 3.5 mA, an open-circuit voltage of 0.85 V, and an off-load power output of 2.97 mW. The triphasic system demonstrates improved structural, electrical, and hydroelectric cell (HEC) performance offering promising prospects for use in magnetoelectric and hydroelectric devices.

Magnetoelectric, dielectric, and magnetic investigations of multiferroic NixCo1−xFe2O4−SryBa1−yNb2O6 composites

Magnetoelectric (NixCo1−xFe2O4)0.3−(SryBa1−yNb2O6)0.7 composites with a 0–3 connectivity and different cation stoichiometries were synthesized via a classical mixed-oxide method. XRD patterns of all ceramics show reflections of the target phases SryBa1−yNb2O6 and NixCo1−xFe2O4. The influence of stoichiometry of the ferrimagnetic and ferroelectric phase on the magnetoelectric behavior was studied on composites with composition of (NixCo1−xFe2O4)0.3−(Sr0.5Ba0.5Nb2O6)0.7 and (NiFe2O4)0.3−(SryBa1−yNb2O6)0.7. The magnetic Curie temperature increases with nickel content. However, the saturation magnetizations as well as the Curie temperatures of the composites are always lower than the ones of bulk NixCo1−xFe2O4 samples. The maximum magnetoelectric coefficient (αME) rises with increasing nickel content from 40 (x = 0) to 180 µV Oe−1 cm−1 (x = 1) in accordance with the dynamic magnetostriction coefficient. The evolution of αME of (NiFe2O4)0.3−(SryBa1−yNb2O6)0.7 composites shows an increase with strontium content up to y 0.5. Higher strontium content leads to a significant reducing of αME.

Recent Developments of Nontraditional Single-Molecule Toroics.

Single-molecule toroics (SMTs), defined as a type of molecules with toroidal arrangement of magnetic moment associated with bi-stable non-magnetic ground states, are promising candidates for high-density information storage and the development of molecule based multiferroic materials with linear magneto-electric coupling and multiferroic behavior. The design and synthesis of SMTs by arranging the magnetic anisotropy axis in a circular pattern at the molecular level have been of great interest to scientists for last two decades since the first detection of the SMT behavior in the seminal Dy3 molecules. DyIII ion has long been the ideal candidate for constructing SMTs due to its Kramer ion nature as well as high anisotropy. Nevertheless, other LnIII ions such as TbIII and HoIII ions, as well as some paramagnetic transition metal ions, have also been used to construct many nontraditional SMTs. Therefore, we review the progress in the studies of SMTs based on the nontraditional perspective, ranging from the 3D topological to 1D&2D&3D polymeric SMTs, and 3d-4f to non Dy-based SMTs. We hope the understanding we provide about nontraditional SMTs will be helpful in designing novel SMTs.

Role of crystal and magnetic structures in the magnetoelectric coupling in CaMn7O12

We investigate the magnetoelectric coupling in CaMn7O12 (CMO) through a comprehensive spectroscopic analysis combining inelastic neutron scattering (INS), x-ray absorption spectroscopy (XAS), and synchrotron-based powder x-ray diffraction (PXRD). CMO's intricate interplay between magnetism and ferroelectricity is dissected to uncover its underlying mechanisms. XAS reveals a mixed valency of Mn ions in CMO, reflecting the presence of Mn3+ and Mn4+ ions, which contributes to its magnetoelectric properties. The double structure in Mn-K near-edge absorption spectra reinforces multiple Mn sites as well as the mixed valency of the compound. Synchrotron-based PXRD experiments conducted over a range of temperatures unveil structural distortions near the magnetic transition temperatures of CMO. These distortions coincide with anomalies in lattice parameters and bond lengths, shedding light on the link between structural modulations and magnetoelectric behavior. Furthermore, INS measurements identify specific energy bands (E1, E2, and E3) associated with distinct exchange interactions between Mn ions. This work advances our understanding of magnetoelectric coupling mechanisms and showcases the potential of multifunctional materials for applications in spintronics and related fields. Published by the American Physical Society 2024

Unleashing the potential: Multifunctionality of PVDF-HFP based ternary nanocomposite films - magnetoelectric, energy harvesting and impact sensing performance

Multifunctional materials are proving to be highly promising for advancing various technologies, including magneto-mechano-electric energy harvesting devices and flexible sensors. This study focused on synthesizing a polyvinylidene fluoride-hexafluoropropylene-metal-oxide-layered silicate nanocomposite system using a cost-effective solution casting technique. The performance of the system was evaluated in terms of magnetoelectric behaviour, energy harvesting capabilities, and impact sensing. The nanocomposite films demonstrated a peak-to-peak voltage of 12.2 V with a filler loading of 15 wt% and an applied force of 9 N, along with a magnetoelectric coupling coefficient of 20.6 mVcm−1Oe−1. The device's ability to scavenge biomechanical energy during body movements like foot stamping, arm bending, finger flexing, and wrist bending was successfully verified. Furthermore, rigorous durability testing was conducted through repeated energy harvesting studies, proving the device's practicality and resilience. Notably, the developed device powered up six LEDs and a digital clock, while the impact sensor exhibited a linear relationship between output voltage and impact force. These findings highlight the remarkable potential of the polyvinylidene fluoride-hexafluoropropylene-metal-oxide-layered silicate nanocomposite system for multifunctional applications in various technological fields.

Imaging of voltage-controlled switching of magnetization in highly magnetostrictive epitaxial Fe-Ga microstructures.

The magnetoelectric behavior of epitaxial Fe-Ga microstructures on top of a (001)-oriented PMN-PT piezoelectric substrate is imaged with magnetic X-ray microscopy. Additionally, the micron-scale strain distribution in PMN-PT is characterized by X-ray microdiffraction and examined with respect to the results of the Fe-Ga magnetoelectric switching. The magnetic reorientation of Fe-Ga is found to be strongly correlated with size, shape, and crystallographic orientation of the microstructures. In the case of square-shaped structures, size dictates the influence of the strain distribution on both the initialization of the ground state and on the magnetic reorientation during application of voltage. On the other hand, elliptical microstructures demonstrate completely different magnetic responses depending on the relative orientation of their long axis with respect to the crystallographic directions of the PMN-PT. This study demonstrates that engineering the behavior of highly magnetostrictive epitaxial microdevices is possible. It further elucidates that voltage-induced actuation can be largely tuned to achieve the desired type of magnetic switching ranging from vortex circulation reversal, domain wall motion, to a large rotation of magnetization. Because of the outstanding properties of the investigated material system, the reported findings are expected to be of great interest for the realization of next-generation energy-efficient magnetic memory and logic devices.

Magnetoelectric behaviour of Pb-free Na0.5Bi0.5TiO3-Ni0.5Co0.5Fe2O4 particulate novel ceramic composites

Magnetoelectric (ME) multiferroic composites are more promising candidates for low-power consumption devices, next-generation spintronic devices, and multistate memory devices since they exhibit significantly higher Magnetoelectric interaction over single-phase multiferroics. In this regard magnetic behaviour, dielectric, and magnetoelectric characteristics of a novel Pb-free (1-x) Na0.5Bi0.5TiO3-(x) Ni0.5Co0.5Fe2O4, (x = 0, 0.2, 0.4, 0.6, 0.8 & 1) particulate composites were explored. Solid-state synthesis was adopted to prepare the single-phase Na0.5Bi0.5TiO3 (NBT), Ni0.5Co0.5Fe2O4 (NCFO), and their composites. The presence of rhombohedral NBT and cubic inverse spinel NCFO in the composites were confirmed with X-ray diffraction (XRD) patterns. Microstrain (ε) induced in the prepared samples was estimated by using the Williamson-Hall (W-H) method. The piezoelectric NBT phase shows the tensile strain and the ferromagnetic NCFO shows the comprehensive strain. Among all the composites 0.8NBT-0.2NCFO shows a higher strain value of 0.012%, and the decrement in the strain values was observed upon increases in ferrite concentration. Backscattered scanning electron microscope (BS-SEM) images revealed the existence of highly dense uniformly distributed elements and Energy dispersive spectroscopy (EDS) confirmed the existing elements in the composites. UV–vis absorbance spectra disclosed a rise in energy gap values from 1.14 eV to 3.0 eV with increasing NBT percentage. Variations of dielectric permittivity and dielectric loss with respect to AC frequency were studied at room temperature (RT), and the 0.2NBT-0.8NCFO sample shows a high dielectric permittivity of 8500 at ∼100Hz. M − H (Magnetization-Magnetic field) hysteresis loops demonstrate the pure ferrite phase has a coercive field (Hc) = 578 Oe, remnant magnetization (Mr) = 21.43 emu/g and saturation magnetization (Ms) = 71.29 emu/g. The Ms and Mr values in the composites are enhanced with increasing ferrite percentage. Studies on ME behaviour of (1-x) NBT-(x) NCFO, (x = 0.2,0.4,0.6 & 0.8) show the coupling effect between both the phases at room temperature and the highest coupling coefficient value 3.16mV/Cm. Oe was observed for the 0.8NBT-0.2NCFO further the reasons and mechanisms are discussed.

Probing magnetoelectric effect in the spin-modulated magnet Fe2GeO4

The distinct spin amplitude wave was reported in a highly frustrated magnetic compound Fe2GeO4, which is very different from observations on other members of the M2GeO4 (M = Fe, Co, and Ni) family, raising interest in this compound for some additional emergent phenomena. In particular, this non-uniform spin order allows the intrinsic connection between ferroelectric polarization and magnetically gradient structure to probe the potential linear magnetoelectric (ME) effect. In this work, we address this issue and investigate the magnetism of Fe2GeO4 single crystal that hosts two successive anomalies at antiferromagnetic (AFM) Néel temperatures T N1 ∼ 7.5 K and T N2 ∼ 6.7 K, respectively. Our results reveal a remarkable metamagnetic transition in the magnetization as a function of the magnetic field, occurring at a critical magnetic field H c ∼ 4.1 T when applied along the [110] and [1–10] directions, while such transition along the [001] direction is pointedly absent. Further exploration uncovers two predominant off-diagonal ME coefficients αyz and αzy in the incommensurate AFM phase between T N1 and T N2. Additionally, all components of the linear ME tensor remain non-vanishing in the canting AFM phase below T N2. This indicates the ME mechanisms for the two phases that may be driven by different magnetic structures. All these presented results are sufficient for us to draw a non-trivial ME phase diagram, which is beneficial to understanding the ME behavior of Fe2GeO4. Therefore, our study implies that Fe2GeO4, an unusual frustrated magnet, provides a platform for manipulating the fascinating ME effect in the spinel structure.

Magnetic Properties of M-Type Hexagonal Ferrite: Mechanical Applications

As the information era continues to advance at a rapid pace, M-type strontium ferrite and other magnetic materials are finding more and more traditional uses. Numerous industries rely on it as a permanent magnet material because of its inexpensive cost, ease of preparation, and outstanding overall performance in areas including electronics, national defense, and communication. In this paper, we investigate some the magnetoelectric coupling properties at room temperature by solid phase method and sol-gel method. The phase structure was determined using an X-ray diffractometer, and the samples were all single-phase polycrystalline with a spatial group of P63/mmc. Observing the surface morphology using field emission scanning electron microscopy, it was found that the composition distribution of the samples prepared by solid-phase method was uneven and there was a "scandium rich phase". The samples prepared by the sol gel method have uniform composition distribution, hexagonal grain shape, and grain size of about 3-5 μ M. The magnetic properties of the samples prepared by the sol gel method and the solid phase method were studied, respectively. The results showed that the phase transition occurred in the solid phase method at about 250K, and the hysteresis loop at room temperature did not show the magnetoelectric coupling behavior. The magnetic phase transition of the sample prepared by the sol gel method occurred near 330K. Combined with the research on the hysteresis loops of the temperature above and below this phase transition point, it shows that this phase transition corresponds to the change of the ferromagnetic to the conical magnetic structure. The similar relationship between magnetic capacitance and magnetization intensity with magnetic field indicates that this conical magnetic structure can induce ferroelectric polarization, which can be understood based on the inverse Dzyaloshinskii-Moriya model.

Magnetoelectric nanoparticles shape modulates their electrical output.

Core-shell magnetoelectric nanoparticles (MENPs) have recently gained popularity thanks to their capability in inducing a local electric polarization upon an applied magnetic field and vice versa. This work estimates the magnetoelectrical behavior, in terms of magnetoelectric coupling coefficient (αME), via finite element analysis of MENPs with different shapes under either static (DC bias) and time-variant (AC bias) external magnetic fields. With this approach, the dependence of the magnetoelectrical performance on the MENPs geometrical features can be directly derived. Results show that MENPs with a more elongated morphology exhibits a superior αME if compared with spherical nanoparticles of similar volume, under both stimulation conditions analyzed. This response is due to the presence of a larger surface area at the interface between the magnetostrictive core and piezoelectric shell, and to the MENP geometrical orientation along the direction of the magnetic field. These findings pave a new way for the design of novel high-aspect ratio magnetic nanostructures with an improved magnetoelectric behaviour.

Investigations on low temperature magnetic and magnetoelectric properties of multiferroic-NiO nanocomposites

Multiferroic BiFeO3-NiO (BFO-NiO) nanocomposites have been synthesized using sol-gel route and investigated via. the first principle DFT calculations, multiferroic-magnetoelectric response, and extremely low-temperature magnetic analysis. Powder X-ray diffraction (XRD) patterns along with Rietveld refinement data confirmed the phase purity viz. rhombohedral distorted perovskite BiFeO3- rock salt type NiO crystal structure and composite formation. Temperature dependent magnetic measurements confirmed the enhancement in the magnetism and the exchange bias effect due to the antiferromagnetic (AFM) and ferromagnetic (FM) exchange coupling interactions. Zero field cooled (ZFC) and field cooled (FC) magnetic results demonstrate the observation of typical superparamagnetic (SP) behavior for all the samples at room temperature whereas at low temperature a transition is reported from SP to quantum superparamagnetic (QSP) state through quantum tunneling of magnetic moment for all samples. Maximum polarization of 5.7μC/cm2 is observed for BFO-20% NiO composition. The noticeable change in the ferroelectric P vs E loops in the presence of external magnetic field confirm the evidence of multiferroic and magnetoelectric coupling behavior in the BFO-NiO nanocomposites. The DFT calculations have been done using WIEN2k software and found in well agreement with the reported experimental results. Further, the suitable temperature dependent magnetic squareness, evidence of considerable magnetoelectric coupling, exchange bias effect and SP nature make the BFO-NiO nanocomposites considerable suitable for various device applications such as information storage, magnetic random access memory, targeted drug delivery, magnetic resonance imaging (MRI), bio-sensing and tailoring other photocatalytic applications.

Flexible magnetoelectric PVDF–CoFe2O4 fiber films for self-powered energy harvesters

Integrating the concept of magnetoelectric in the mechanical energy harvesters through the magneto-mechano-electrical (MME) nanogenerators has been explored to realize the self-powered devices. The magnetoelectric interaction enabled the output performance of the MME nanogenerator under magnetic stimulus of the active components of the energy harvesters. In this perspective, we fabricated a flexible biomechanical and MME nanogenerator using PVDF/CoFe2O4 fibers composite films. CoFe2O4 fibers were synthesized by the electrospinning technique and the process parameters were optimized to achieve uniform and bead-free fibers. The structural and morphological properties were investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The structural and morphology revealed the fibers calcined at 800 °C with a heating rate of 2 °C/min produced bead-free continuous fibers with a fiber diameter of 210 nm with cubic spinel crystalline structure with a crystallite size of 34 nm. These highly crystalline fibers were used to fabricate PVDF/CoFe2O4 fibers composite films. The magnetoelectric behaviour of the films verified through polarization vs. electric field (P-E) loops under magnetic field. The leakage current density and mechanism of the composite films were investigated, and it was discovered that the mechanism was due to Schottky emission. Further the energy harvesting performance of the composite films were estimated where the nanogenerator achieved an output voltage of 13 V under biomechanical tapping force while the MME nanogenerator produced 3.5 V under a low frequency stray magnetic field of 6 Oe with a power density of 28 μW/m2.

Enhanced multiferroicity of Ho0.95Co0.05Fe0.95Ti0.05O3 by co-doping in HoFeO3 nanoparticle system

Nanocrystalline HoFeO3 is a potential multiferroic and will be more useful if its multiferroicity can be enhanced by improving the magnetic and electric ordering. In this regard, co-doping with Co and Ti, was considered in HoFeO3 (HFO) to enhance its magneto-electric behavior and thus synthesize a new monophasic multiferroic, Ho0.95Co0.05Fe0.95Ti0.05O3 (HCFTO). Both the pristine and doped HFO nanoparticles were synthesized in sol–gel route. Rietveld analyses of X-ray diffractograms, confirmed the formation of pure orthorhombic (Pnma) phase of both bare and doped HFO. Presence of the canted antiferromagnetism of bare HFO at room-temperature with antiferromagnetic transition at ∼ 637 K was confirmed in susceptibility vs. temperature variation and by the nature of MH loops. Interestingly, substantial enhancement of magnetism was observed in HCFTO compared to that of bare one, where the room-temperature maximum magnetization is enhanced by 73%. Dielectric strength of HFO (∼48) is also enhanced highly (∼3.4 times) in HCFTO (∼165), and the loss factor is lowered to nearly half. Current density vs. electric field (J-E) curve suggests the presence of polarization at room temperature with negligible leakage loss. Lower leakage loss of HCFTO indicates better multiferroicity than HFO. Direct measurement of ferroelectric loop shows the room-temperature ferroelectricity of bare HFO (Pmax ∼ 0.0041 µc/cm2) well improved (∼1.5 times) in the doped HCFTO (Pmax ∼ 0.0061 µc/cm2) with lower hysteresis loss. Room-temperature magnetoelectric coupling measurements, shows a high value (∼2.47%) of magnetocapacitance in the doped system, which is much higher (∼4.94 times) than the bare one (∼0.5%). All these properties of the sample clearly confirm the co-doping in the HoFeO3 nanoparticle system results in a considerable improvement in its magnetoelectric behavior, and this co-doped Ho0.95Co0.05Fe0.95Ti0.05O3 system can be a promising and potential magnetoelectric multiferroic for device applications.

Room temperature multiferroicity of hexagonal LuFeO3 and its enhancement by co-doping in Lu0.9Co0.1Fe0.9Ti0.1O3 nanoparticle system

Antiferromagnetic LuFeO3 can be good multiferroic by having ferroelectricity in its non-centrosymmetric hexagonal phase. But, it is hard to stabilize this metastable phase, preventing the stable orthorhombic phase. In this work, metastable hexagonal LuFeO3 (LFO) nanoparticle was stabilized in chemical sol-gel route in pure phase and co-doped with Co and Ti in the same route to synthesize Lu0.9Co0.1Fe0.9Ti0.1O3 (LCFTO) nanoparticles. Room temperature multiferroicity of bare LFO was established through relevant characterization. And motive behind the co-doping is to enhance the magnetoelectric behavior of the bare system to synthesize a new monophasic type II magnetoelectric multiferroic. Structural investigation by thorough Rietveld analyses of the recorded X-ray diffractograms, confirmed the formation of pure hexagonal (P63cm) phase of both bare and doped LFO. However, deviations in various structural & microstructural parameters were observed in the doped system, which is mainly responsible for the enhancement of magnetic and electric properties of the sample. Presence of antiferromagnetic transition at ∼604 K confirmed the room temperature magnetic ordering of bare LFO. Interestingly, LCFTO shows a drastic enhancement of magnetic property than the bare one in all concerns, where the maximum magnetization at the maximum applied field is enhanced by nearly 36 times at room temperature. Detailed high-temperature dielectric investigation shows, good dielectric strength (∼261) of LFO gets enhanced highly in LCFTO (∼1053) and a high relaxation time having negligible loss factor with an indication of ferro to paraelectric transition above room temperature. Current density vs. electric field (J-E) curve suggests the presence of polarization at room temperature with negligible leakage loss. Direct measurement of ferroelectric loop shows the ferroelectricity (Pmax∼0.064 µc/cm2) of bare LFO at room temperature and a well improvement in the doped LCFTO (Pmax∼0.151 µc/cm2). The presence of room temperature magnetoelectric coupling, confirmed by magnetocapacitance measurements, results in a high value (∼5 %) of magnetocapacitance in the doped system which is also much higher than the bare one (<∼1 %) as expected. All these properties confirm the magnetoelectric multiferroicity of bare h-LuFeO3 at room temperature. And, co-doping in hexagonal LuFeO3 nanoparticle system results in a considerable improvement in its magnetoelectric behavior, so this co-doped system can be a promising and potential magnetoelectric multiferroic for the future generation magnetoelectric devices.

Magnetic ordering and chirality in multiferroic Dy1-xHoxMnO3 (x = 0.2)

Effect of substitution Dy by Ho on the magneto-electric behavior of the compound Dy0.8Ho0.2MnO3 was investigated by the different methods of polarized and classical neutron diffraction and macroscopic methods. It is shown that substitution by Ho of 20% on the position of Dy do not change overall crystal symmetry of compound. It remains of Pbnm type down to the very low temperatures. Magnetic ordering, its temperature and field evolution was determined by the use of single crystal neutron diffraction and magnetization measurements. Chiral type of magnetic structure on Mn subsystem is confirmed below Tc ≈ 16 K. Using polarized neutron diffraction the 3-component character of rare earth magnetic ordering in Dy0.8Ho0.2MnO3 in contrast to DyMnO3 could be revealed. It was shown that doping by 20% Ho suppresses the spontaneous rare-earth ordering with its own propagation vector and provides the situation when two magnetic subsystems, manganese and rare earth ones have a coherent incommensurate spatial propagation. The influence of the external electric field on the magnetic chirality could be directly evidenced, proving strong magneto-electric coupling in multiferroic phase. The study of the electric polarization under similar temperatures and fields on the same samples provides the direct correlation between the results of the microscopic and macroscopic investigations.

Effect of Poly‐Crystallinity on the Magnetoelectric Behavior of TiN/AlN/Ni MEMS Cantilevers Investigated by Finite Element Methods

Herein, magnetoelectric microelectromechanical system (MEMS) cantilevers are investigated on basis of a TiN/AlN/Ni laminate derived from experimental sensors using finite‐element simulations. With the anisotropic ΔE effect as an implication of the magnetocrystalline anisotropy, the lateral sensitivity of the sensor is studied for different nickel layer thicknesses and boundary conditions. It is found that above 60% of the cantilever length, the nickel is effectively not contributing to the sensor sensitivity anymore which is supported by the investigation of sensors with partial nickel coverage. The boundary condition of the magnetostrictive layer is found to affect the sensitivity of thick layers while it is negligible for thinning layers. Further investigations on basis of polycrystalline untextured nickel with slightly preferred orientations reveal a stronger effect on thin layers than on thicker ones. It is found to arise from relatively large crystals in the high‐sensitivity region near the clamping of the sensor. For thicker polycrystalline layers, the ΔE effect reproduces a characteristic based mainly on the (110) and (111) orientations while the (100) orientation appears to be underrepresented.

Strong modulation effects on magnetoelectric behavior of Co-ferrite nanoparticles incorporated in ZnO medium in nano-regime synthesized in chemical routes

Strong modulation effects on magnetoelectric behavior of Co-ferrite nanoparticles incorporated in ZnO medium in nano-regime synthesized in chemical routes

Direct magnetoelectric and magnetodielectric studies of electrospun Ba2Ni2Fe12O22–Pb(Zr0.52Ti0.48)O3 core–shell nanofibers

This article reports the synthesis of barium nickel hexaferrite-lead zirconium titanate (Ba2Ni2Fe12O22-Pb(Zr0.52Ti0.48)O3) core-shell nanofibers through sol-gel electrospinning method. Direct magnetoelectric and magnetodielectric coupling studies were performed on the synthesized electrospun core-shell nanofibers. The structure, functional, morphological, magnetic, dielectric, leakage current, and ferroelectric properties were also analyzed. X-ray diffraction studies revealed the hexagonal crystal structure of the core and the tetragonal structure of the shell. The Fourier transform infrared spectroscopy analysis showed the fundamental functional groups present in the nanofibers. Scanning electron microscopy studies showed that the diameter of the nanofibers was 404 nm, and elemental analysis by energy-dispersive X-ray spectroscopy showed the stoichiometric formation of Ba2Ni2Fe12O22 and Pb(Zr0.52Ti0.48)O3 in the composite. Microstructure studies using a transmission electron microscope revealed the formation of core-shell nanofibers with a clear interface between the magnetic Ba2Ni2Fe12O22 (BNFO) core and the ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) shell. Selected-area electron diffraction analysis showed the Ba2Ni2Fe12O22 and Pb(Zr0.52Ti0.48)O3 phases to be highly crystalline. At room temperature, the synthesized nanofibers exhibited well-defined ferroelectric and magnetic hysteresis loops. Dielectric and leakage current studies were performed. Direct magnetoelectric and magnetodielectric studies were also performed to study the cross-coupling between the ferroic orders of the nanofiber. Moreover, using Landau’s energy expression, the type of magnetoelectric coupling was proved to be biquadratic. The enhanced magnetoelectric behavior of the Ba2Ni2Fe12O22–Pb(Zr0.52Ti0.48)O3 core–shell nanofiber confirms that the nanofiber is a potential candidate for high-performing magnetic field sensors, magnetically tuned capacitors, multimedia transducers, and spintronic devices.

Modeling of core-shell magneto-electric nanoparticles for biomedical applications: Effect of composition, dimension, and magnetic field features on magnetoelectric response.

The recent development of core-shell nanoparticles which combine strain coupled magnetostrictive and piezoelectric phases, has attracted a lot of attention due to their ability to yield strong magnetoelectric effect even at room temperature, thus making them a promising tool to enable biomedical applications. To fully exploit their potentialities and to adapt their use to in vivo applications, this study analyzes, through a numerical approach, their magnetoelectric behavior, shortly quantified by the magnetoelectric coupling coefficient (αME), thus providing an important milestone for the characterization of the magnetoelectric effect at the nanoscale. In view of recent evidence showing that αME is strongly affected by both the applied magnetic field DC bias and AC frequency, this study implements a nonlinear model, based on magnetic hysteresis, to describe the responses of two different core-shell nanoparticles to various magnetic field excitation stimuli. The proposed model is also used to evaluate to which extent realistic variables such as core diameter and shell thickness affect the electric output. Results prove that αME of 80 nm cobalt ferrite-barium titanate (CFO-BTO) nanoparticles with a 60:40 ratio is equal to about 0.28 V/cm∙Oe corresponding to electric fields up to about 1000 V/cm when a strong DC bias is applied. However, the same electric output can be obtained even in absence of DC field with very low AC fields, by exploiting the hysteretic characteristics of the same composites. The analysis of core and shell dimension is as such to indicate that, to maximize αME, larger core diameter and thinner shell nanoparticles should be preferred. These results, taken together, suggest that it is possible to tune magnetoelectric nanoparticles electric responses by controlling their composition and their size, thus opening the opportunity to adapt their structure on the specific application to pursue.