Magnetoelectric Properties Research Articles

Enhanced Stability of the Multiferroic Phase in Cr-Doped Y -Type Hexaferrite Single Crystals

The material family of $Y$-type hexaferrites is among the most promising candidates for magnetoelectric memory applications. The magnetoelectric properties in this class of magnets are dominated by a multiferroic phase, termed the FE3 phase, where spin-driven polarization can be switched by a magnetic field, and, conversely, a full magnetic moment can be reversed by an electric field. In this study, we discuss the effect of Cr doping on the stability of competing magnetic and multiferroic phases in the $Y$-type hexaferrites ${\mathrm{Ba}\mathrm{Sr}\mathrm{Co}}_{2}{\mathrm{Fe}}_{12\ensuremath{-}x\ensuremath{-}\ensuremath{\delta}}{\mathrm{Al}}_{x}{\mathrm{Cr}}_{\ensuremath{\delta}}{\mathrm{O}}_{22}$ with $x=0.9$ and $\ensuremath{\delta}=0.00$, 0.05, and 0.10. We find that Cr doping increases the stability of the multiferroic FE3 phase; while in the Cr-free compound the alternating longitudinal conical (ALC) and proper screw phases are stabilized as zero-field-cooled magnetic phases, the FE3 phase appears besides the ALC phase as a stable zero-field-cooled phase in the $\ensuremath{\delta}=0.05$ and 0.10 compounds. Moreover, a spin-induced large polarization is observed at and above room temperatures with antisymmetric magnetic field dependence. The magnetoelectric properties, in particular the coupling between polarization and magnetization, are investigated via the measurements in the simultaneous presence of electric and magnetic fields. We find the enhanced stability of the magnetoelectic responses from the multiferroic FE3 phase upon Cr doping, while the coupling between the polarization and magnetization is preserved.

Effect of sintering temperature on magnetoelectric properties of barium ferrite ceramics

Effect of sintering temperature on magnetoelectric properties of barium ferrite ceramics

The study of CoFe2O4/Ba0.85Ca0.15Zr0.1Ti0.9O3-laminated composite ceramic on dielectric, relaxation, ferroelectric, and magnetoelectric coupling properties

The study of CoFe2O4/Ba0.85Ca0.15Zr0.1Ti0.9O3-laminated composite ceramic on dielectric, relaxation, ferroelectric, and magnetoelectric coupling properties

Unravelling the magnetodielectric characteristics of strain-coupled PMN-PT/FSMA multiferroic heterojunction toward flexible MEMS applications

Flexible microelectromechanical (MEMS) devices are poised to scaffold technological innovations in the fields of wearable sensors, implantable health monitoring systems and touchless human-machine interaction. Here, we report the magnetoelectric properties of cost-effective and room-temperature sensitive 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3/Ni50Mn35In15 (PMN-PT/ferromagnetic shape memory alloy (FSMA)) multiferroic heterostructure integrated on flexible stainless steel substrate via RF/DC magnetron sputtering technique. The growth of the pure perovskite phase of PMN-PT without any pyrochlore impurity is confirmed by the dominant (002) orientation of the tetragonal PMN-PT. The double logarithmic plot of current density with electric field validates the Ohmic conduction mechanism with low leakage current density of ∼10−6 A cm−2. The anomaly observed in temperature-dependent dielectric and ferroelectric characteristics of the heterostructure overlap with the martensite transformation regime of the bottom Ni–Mn–In (FSMA) layer. The PMN-PT/Ni–Mn–In multiferroic heterostructure exhibits a significant magnetodielectric effect of ∼3% at 500 Oe and can be used as an ultra-sensitive room-temperature magnetic field sensor. These results have been explained by an analytical model based on strain-mediated magnetoelectric coupling between interfacially coupled PMN-PT and Ni–Mn–In layers of the multiferroic heterostructure. Furthermore, the excellent retention of magnetodielectric response up to 200 bending cycles enhances its applicability towards flexible MEMS devices. Such PMN-PT based multiferroic heterostructures grown over the flexible substrate can be a potential candidate for piezo MEMS applications.

CO2 gas sensor based on Pt-, Ag-, Au- and Pd-doped InSe monolayer: a first-principles study

Through a first-principles study based on density functional theory, a physical model of CO2 gas molecule adsorption on an InSe monolayer was designed and built. The geometric structures of the InSe monolayer doped with different transition metal elements were optimized, and the spin-polarized energy band structure and magnetoelectric properties, such as the density of states, semimetallicity and magnetic moment of nanosheets with stable adsorbed phases, were calculated. The microscopic mechanism of these properties was analyzed by crystal field theory, and it was found that InSe monolayers are typical semiconductors, but transition metal–InSe monolayers can conduct electricity and are typical semi-metallic nanosheets. Second, the adsorption mechanism of CO2 gas molecule adsorption on InSe monolayers is studied. The calculation results show that when the O atom of the CO2 gas molecule is adsorbed on the surface of an InSe monolayer, the adsorption structure is relatively stable. The surface adsorption is mainly due to the transition of electrons on the InSe monolayer surface to the CO2 gas molecule. The doping of metal atoms gives CO2 gas molecules strong adsorption energy, promotes the magnetic properties of the adsorption system, and completes the transition from semiconductor to metal. The change of the work function of the adsorption system before and after doping indicates that this doping method can also enhance the sensitivity of the InSe monolayer to CO2 gas molecules.

Anti-Electromagnetic Interference Design of Rail Transit Vehicles Based on the Magnetic Induction and Magnetoelectric Characteristics of Ferroelectric Ceramics

The various properties of ferroelectric ceramics bring extremely rich colors to life. Its various properties such as dielectric properties, electromagnetic properties, and anti-magnetic interference properties have been successively studied in various fields, except for stone carvings, outdoor environmental sculptures, ornamental ceramics, etc. Because of its superior performance, it can also be used in aircraft manufacturing, anti-interference materials for train tracks, and can even realize unmanned driving, workshop networks and other environments, which can meet the normal operation of electronic equipment in the car under the state of preventing external electromagnetic interference. This requires the superior electromagnetic properties of ferroelectric ceramics. Dielectric properties, dielectric relaxation, and ferromagnetic effects all need to be optimized. This article first introduces the performance test methods of ferroelectric ceramics, and describes the dielectric relaxation through Debye equation He phenomenon, test dielectric loss and dipole interaction, magnetic coupling effect and multiferrocity, and carry out electromagnetic coexistence, based on MATLAB/Simulink rail vehicle dynamics model, composed of sensors, control center and bogie, forming a coupling The functioning anti-roll structure makes the magnetic potential energy evenly distributed in the track span, forming a single suspended electromagnet modular transportation train dynamic model, which can carry the load force of the air and the gravity of the module itself. The traditional solid-phase method is used to dope at the A site. As the doped sample gradually increases, the peak value of the derivative peak changes, causing the original diamagnetic sample to carry a certain degree of ferromagnetism, and the doping amount and ferromagnetism are positively correlated. Then, experiments were performed on the composite ferroelectric ceramic materials doped with ion pairs, and the tests were carried out at different temperatures and different doping amounts. The conclusions about the coupling of dielectric constant, dielectric loss, magnetic properties and magneto electric properties were obtained and obtained the anti-magnetic interference ability. The application in the anti-magnetic interference of rail trains has a certain guiding effect. The results show that when the doping amount reaches m = 0.02, the dielectric loss is reduced by 22.58 times. The impedance change rate of the ferroelectric ceramic material with no doped Al3 +-Li + ion pair under 9 kOe is 3.95%, while at m = 0.015 Al3+ With -Li + doping, the impedance change rate of ferroelectric ceramics is 14.45%, which is 3.17 times the original.

Enhanced magnetic properties and magnetodielectric effects in Bi2Fe4O9/BaTiO3 composite

The magnetoelectric properties of Bi2Fe4O9 were improved by compounding with BaTiO3. The magnetic results showed enhanced magnetization in Bi2Fe4O9/BaTiO3 composite compared with Bi2Fe4O9, which originated from the substitution of some Fe atoms in the Ti position of BaTiO3. Bi2Fe4O9/BaTiO3 possessed dielectric relaxation in the temperature range of 120–250 K, which was ascribed to the electron hopping process asymmetrically between Fe2+ and Fe3+. Bi2Fe4O9 and Bi2Fe4O9/BaTiO3 composite both exhibited magnetodielectric effects with an applied magnetic field, indicating magnetoelectric coupling. The maximum coupling coefficient Δε/ε in Bi2Fe4O9/BaTiO3 was approximately − 4.43 % (H = 4000 Oe, f = 0.1 MHz), which was 10 times higher than that of Bi2Fe4O9. The magnetodielectric effects in Bi2Fe4O9 were from the spin-lattice coupling, and the enhanced results in Bi2Fe4O9/BaTiO3 mainly affected by the dielectric relaxation were related to the spin-orbit coupling. In Bi2Fe4O9/BaTiO3, the applied magnetic field altered the energy level of electrons for the Fe2+ (3d6) ion in FeO6 octahedron and then changed the state of electron polarization, which finally gave rise to a change in the dielectric constant. In addition, the stress transfer between the interfaces of Bi2Fe4O9 and BaTiO3 in the composite under a magnetic field also contributed to the magnetodielectric effects.

BaTiO3/(Co0.8Ni0.1Mn0.1Fe1.9Ce0.1O4)x composites: Analysis of the effect of Co0.8Ni0.1Mn0.1Fe1.9Ce0.1O4 doping at different concentrations on the structural, morphological, optical, magnetic, and magnetoelectric coupling properties of BaTiO3

In the present study, composite samples of BaTiO3/(Co0.8Ni0.1Mn0.1Fe1.9Ce0.1O4)x (noted as BTO/(CNMFCO)x) were prepared and their structural, morphological, optical, magnetic, and magnetoelectric coupling properties were investigated. Firstly, the BaTiO3 and spinel ferrite CNMFCO phases were prepared separately through the sol-gel auto-combustion route, then, the composite samples BTO/(CNMFCO)x were made via the solid-state reaction method. The structural, morphological, optical, magnetic, and magnetoelectric coupling properties were examined using X-rays diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), scanning electron microscope (SEM) coupled with EDX spectrometer, UV–visible diffuse reflectance spectrophotometer (UV–vis DRS), vibrating sample magnetometer (VSM) techniques, and lock-in amplifier, respectively. The successful preparation of biphasic samples was confirmed by XRD and SEM studies. From SEM images, a compact structure with good density was observed. The mean size of BTO grains decreases with increasing the concentration of the magnetic phase. The optical properties have been explored in the UV–visible light range. The extracted band gap energy (Eg) values showed a reduction with the rising of the magnetic phase content. The analysis of magnetization measurements revealed the magnetic character of different composites. It is found that the saturation (Ms) and remanent (Mr) magnetizations are increasing with the rise in the concentration of the magnetic CNMFCO phase (x %). High magnetoelectric voltage coefficients (αME) were attained for different composites with the highest αME value of about 22.8 mV/cm.Oe reached in composite with x content of 20%. The high ME coupling in these composites makes these composites promising candidates to be used in multifunctional devices.

Magnetic and magnetoelectric properties of NixCu1–xFe2O4–PbZr0.52Ti0.48O3 single and multilayered thick films

Magnetic and magnetoelectric properties of NixCu1–xFe2O4–PbZr0.52Ti0.48O3 single and multilayered thick films

Anomalous Response in the Orbital Magnetic Susceptibility of 2D Topological Systems

2D compounds with nonzero Berry curvature are ideal systems to study exotic and technologically favorable thermoelectric and magnetoelectric properties. Within this class of materials, the topological trivial and nontrivial regimes have to present very different behaviors, which are encoded for the orbital susceptibility and magnetization. To try to reveal them, it is found that it was necessary to introduce a k‐dependent mass term in the relativistic formalism of these materials. Thus, while a topologically trivial insulator is predicted to have a very limited response, in the nontrivial regime, a singular contribution to the orbital magnetic susceptibility, which is inversely proportional to the square of the quantum magnetic flux is unveiled. In this scenario, besides determining the measurement conditions a new route for enhancing the intrinsic orbital magnetism of topological materials widening the range of temperatures and magnetic fields without involving tiny bandgaps is found.

Electric-Field-Tunable Transport and Photo-Resistance Properties in LaMnO3−x/PMN-PT Heterostructures

Multiferroic heterojunctions are promising for application in low-power storage and spintronics due to their magnetoelectric coupling properties. Controlling the magnetic and transport properties of magnetic materials by external stimuli and then realizing advanced devices constitute the key mission in this field. We fabricated a multiferroic heterostructure consisting of a ferroelectric single-crystal (001)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 substrate and an epitaxial 40 nm LaMnO3−x film. By applying dc electric fields to the ferroelectric substrate, the resistance and the photo-resistance of the LaMnO3−x film could be significantly modulated. With the electric field increasing from 0 to +4.8 kV/cm, the photo-resistance increased by ~4.1% at room temperature. The curve of photo-resistance versus the cycling electric field has a butterfly shape due to the piezoelectric strain effect. Using in situ X-ray diffraction measurements, the linear relationship of the strain and the electric field was quantitatively studied.

Influence of Eu3+ substitution on structural, magnetic and dielectric properties of Bi0.9La0.1FeO3

Enhanced magneto-electrical (ME) properties of BiFeO3 multiferroics are attained by the modification of structural morphology that is essential for the possible applications in multifunctional devices like miniaturization. This study focused on the improvement of the magnetic and dielectric properties in an ideal BiFeO3 achieved by the gradually substitution of Eu3+in place of Fe3+ (B-site) with slight addition of La3+ replacing Bi3+ (A-Site). In this regards the composition Bi0.9La0.1Fe1-xEuxO3 (x = 0, 0.02, 0.05, 0.07, 0.10 and 0.15) were synthesized by solid state reaction method. XRD patterns indicate the samples crystallize with the normal distorted rhombohedral phase (R3c space group) and oxygen vacancies are significantly suppressed by the increase of Eu3+ amount. The lowest porosity (1.9%) is observed in the sample for x = 0.07. The crystallite sizes are increased due to 15% Eu doping. The average size of the grains are observed to be increased in the micrograph for Eu doping compared to the undoped one. The strongest absorbance peak around 560 cm−1 in FTIR spectroscopy for all the samples confirm the octahedral FeO6 bonding while a pair of feeble peaks around 370 cm−1 and 440 cm−1 confirm the existence of BiO6 octahedral phase adjacent with FeO6 group. The magnetic saturation (Ms) is 0.89 emu/g for the undoped Bi0.9La0.1FeO3 and Ms increases for Eu3+ substitution at the Fe-site of the compound. The maximum Ms (1.58 emu/g) is observed in the sample for x = 0.07. The permeability (μ) and permittivity (ε) are highly affected by the reformed structure with various grain sizes and porosities (%) which have been reported in this work. The composition for 7% Eu3+ doping shows an excellent matching between μ’ and ε’ (μ’/ε’=0.9) with lower magnetic loss (tanδμ = 0.0133) over the frequency range from 1 MHz to 100 MHz.

Room-temperature surface multiferroicity in Y2NiMnO6 nanorods

We report observation of surface-defect-induced room-temperature multiferroicity---surface ferromagnetism (${M}_{S}$ at 50 kOe $\ensuremath{\approx}0.005$ emu/g), ferroelectricity (${P}_{R}\ensuremath{\approx}2\phantom{\rule{0.16em}{0ex}}\mathrm{nC}/{\mathrm{cm}}^{2}$), and significantly large magnetoelectric coupling (decrease in ${P}_{R}$ by $\ensuremath{\approx}80%$ under $\ensuremath{\approx}15$ kOe field)---in nanorods (diameter $\ensuremath{\approx}100$ nm) of double perovskite ${\mathrm{Y}}_{2}{\mathrm{NiMnO}}_{6}$ compound. In bulk form, this system exhibits multiferroicity only below its magnetic transition temperature ${T}_{N}\ensuremath{\approx}$ 70 K. On the other hand, the oxygen vacancies, formed at the surface region (thickness $\ensuremath{\approx}10$ nm) of the nanorods, yield long-range magnetic order as well as ferroelectricity via Dzyloshinskii-Moriya exchange coupling interactions with strong Rashba spin-orbit coupling. Sharp drop in ${P}_{R}$ under magnetic field indicates strong cross coupling between magnetism and ferroelectricity as well. Observation of room-temperature magnetoelectric coupling in nanoscale for a compound which, in bulk form, exhibits multiferroicity only below 70 K underscores an alternative pathway for inducing magnetoelectric multiferroicity via surface defects and, thus, in line with magnetoelectric property observed, for example, in domain walls or boundaries or interfaces of heteroepitaxially grown thin films which do not exhibit such features in their bulk.

Crystal structure and magnetoelectric properties of CrFeO3-doped BaZr0.1Ti0.9O3 multiferroic ceramics

Chromium ferrite-doped barium zirconate titanate multiferroic materials in (1-x)BaZr0.1Ti0.9O3 – (x)CrFeO3; BZT-CF) system, when x = 0, 2, 4, 6, 8 and 10 mol%, were prepared by the solid-state reaction technique. Phase formation, lattice parameter, and electronic state of materials were characterized by x-ray diffraction (XRD) and x-ray absorption near-edge spectroscopy (XANES) techniques. It was found that the undoped BZT ceramic showed a single tetragonal phase without the secondary phase. However, CF-doped BZT ceramic at 2–10 mol% reveals that the tetragonal phase was changed to the orthorhombic phase. Lattice parameter and dislocation density have increased with increasing CrFeO3 content, representing the crystal structure's imperfection in interesting material. The magnetic and magnetoelectric of materials were characterized by the vibrating sample magnetometer (VSM) technique. It was found that all-ceramic exhibits a paramagnetic behavior. However, all doped ceramics showed a magnetic field response value better than undoped, with a maximum magnetodielectric coefficient (ME) of 18.3 × 10−3 at 2 mol% of CF-doped.

Phase evolution and enhanced piezoelectric, multiferroic, and magnetoelectric properties in Cr–Mn co-doped BiFeO3–BaTiO3 system

Phase evolution and enhanced piezoelectric, multiferroic, and magnetoelectric properties in Cr–Mn co-doped BiFeO3–BaTiO3 system

Evolution of microstructure and properties in BT-based lead-free magnetoelectric composite

Owing to the excellent conversion properties between magnetic and electric properties, magnetoelectric composites have been widely used in devices. With the growing concerns about the environment, developing environmentally friendly lead-free magnetoelectric composites with high performance are very important. Here, (1-x)0.82Ba(Ti0.89Sn0.11)O3-0.18(Ba0.7Ca0.3)TiO3-xCoFe2O4 [(1-x)BTS-BCT-xCFO] magnetoelectric composites are synthesized by solid-state method, and the effect of CFO on the microstructure and magnetoelectric properties is systematically studied. The perovskite type piezoelectric phase and spinel structured piezomagnetic phase in diffraction patterns are independent of each other. Due to the inhibiting effect of CFO on grain size for BTS-BCT, the grain size of magnetoelectric composites is dominated by CFO. The electric properties deteriorate, and magnetic properties increase with increasing CFO. Meanwhile, the optimal ME coefficients (αE31∼8.12 mV/cm∙Oe and αE33∼7.84 mV/cm∙Oe) are obtained in the (1-x)BTS-BCT-xCFO with x = 0.20, which are superior or comparable to that of some lead-based and lead-free magnetoelectric composites. Therefore, (1-x)BTS-BCT-xCFO material systems have a promising prospect in application.

Analysis of magnetoelectric properties of Cu-PZT layered composite structure for passive sensing

With the construction of the energy internet, the demand for various sensing devices is increasing. Most of sensing devices need power source which limits their application in the wide spread distributed nodes of sensor network. Therefore, there is an urgent need to develop passive sensing devices which is more intelligent and convenient. This paper studies the magnetoelectric effect of layered magnetoelectric composites. Firstly, the physical process is analyzed by using the finite element method. Secondly, magnetoelectric response of the eddy current in the Cu-PZT layered composite material is investigated. Finally, the voltage variations of circular and rectangular samples are compared. It can be seen from the results that under the action of the eddy current, there is a u-shaped curve relationship between the induced voltage and the magnetic field. The energy conversion of metal-piezoelectric composite material without power source provides an effective path for developing passive magnetic sensor.

Multiferroic and energy harvesting characteristics of P(VDF-TrFE)-CuFe2O4 flexible films

Ferroelectric polymer-based multiferroics are very promising candidates for a wide variety of applications. To realize such a composite material with remarkable multiferroic behavior, we have developed CuFe 2 O 4 nanoparticles loaded poly (vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) films by a solvent casting approach. Different weight percentages (2, 4, 8 and 16) of CuFe 2 O 4 nanoparticles were achieved in the P(VDF-TrFE) matrix. Remarkable improvement in the multiferroic behavior has been observed with the addition of the magnetic nanoparticle. Through this approach, by adjusting the filler content we could vary the magnetoelectric coupling coefficient from 6.12 to 26.31 mVcm −1 Oe −1 . The piezoelectric energy harvesting performances of the prepared multiferroic materials were also studied. The energy harvesting devices based on the developed materials were produced output voltages between 3 and −3 V during repeated pressure imparting. • CuFe 2 O 4 nanoparticles loaded P(VDF-TrFE) films were developed by a solvent casting approach. • Dielectric, magnetic and magnetoelectric properties of the composites were enhanced with CuFe 2 O 4 nanoparticles loading. • The highest ME coefficient of 26.31 mVcm −1 Oe −1 was noticed for the composite film with 16 wt% of CuFe 2 O 4 nanoparticles. • Developed PEHDs produced output voltages between 3 and −3 V during repeated pressure imparting.

Influence of gamma radiation on magnetoelectric properties of extruded samples of solid solution Bi85Sb15〈Te〉 modified ZrO2

The electrical and thermal properties of extruded samples of Bi[Formula: see text]Sb[Formula: see text] [Formula: see text] modified with ZrO2 were investigated depending on the dose of gamma radiation in the temperature range [Formula: see text] K and magnetic field strength (H) [Formula: see text] A/m. It was found that an increase in the mobility in the irradiated modified Bi[Formula: see text]Sb[Formula: see text] [Formula: see text] is associated with the radiation introduction of acceptor (negatively charged) centers, which at low doses are generated mainly in the regions of the efficiency of impurity scattering of charge carriers and partially neutralized centers and, accordingly, to a certain increase in the mobility. In the extruded modified samples of the Bi[Formula: see text]Sb[Formula: see text] solid solution, irradiation with gamma quanta results not only in the generation of radiation defects (RDs) (centers), but also accompanied by their rearrangement. This causes a change in the spectrum of localized states and the electron scattering process, which leads to corresponding changes in the presented electrical and thermal parameters.

Tunable excitons in rhombohedral trilayer graphene

Trilayer graphene is receiving an increasing level of attention due to its stacking--dependent magnetoelectric and optoelectric properties, and its more robust ferromagnetism relative to monolayer and bilayer variants. Additionally, rhombohedral stacked trilayer graphene presents the possibility of easily opening a gap via either an external electric field perpendicular to the layers, or via the application of external strain. In this paper, we consider an external electric field to open a bandgap in rhombohedral trilayer graphene and study the excitonic optical response of the system. This is done via the combination of a tight binding model with the Bethe--Salpeter equation, solved semi--analytically and requiring only a simple numerical quadrature. We then discuss the valley--dependent optical selection rules, followed by the computation of the excitonic linear optical conductivity for the case of a rhombohedral graphene trilayer encapsulated in hexagonal boron nitride. The tunability of the excitonic resonances via an external field is also discussed, together with the increasing localization of the excitonic states as the field increases.