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Effect of the Yb dopant on the structural, magnetic, and electrical properties of the multiferroic BiFeO3 have been studied. The structural properties of sol-gel derived Bi1-xYbxFeO3 (x=0.0, 0.1, and 0.2) nanoparticles reveal the formation of a rhombohedrally distorted perovskite in XRD and a reduction in the average grain size have been observed with an increase in the Yb concentration. Microstructural studies exhibited the formation of sphere like morphology with decreasing particle size with increase in the dopant concentration. The effective doping also resulted in larger magnetization as well as coercivity with the maximum of 257 Oe and 1.76 emu/g in the Bi0.8Yb0.2FeO3 nanoparticles. Ferroelectric as well as dielectric properties of the nanoparticles were also improved on doping. The best results were obtained for the BiFeO3 nanoparticles having Yb concentration x=0.2. [ABSTRACT FROM AUTHOR]

With the development of electronic information technology, the miniaturization of lightweight devices and their integration have increased the requirements for materials, and two-dimensional composite multiferroic materials have become a major research hotspot in recent years. However, it is difficult for traditional solid multiferroic material to directly switch the magnetic/polarization direction under the action of an applied electric/magnetic field, limiting the improvement of the magnetoelectric coupling coefficient. In this study, a series of BiFeO 3 (BFO)/CoFe 2 O 4 (CFO) composite film multiferroic materials were prepared by changing the annealing routes and annealing atmosphere, the microstructure, ferroelectric properties, dielectric properties, photovoltaic properties, magnetic properties, and magnetoelectric coupling properties of composite films were routeatically studied. The results showed that under the slow annealing route, the composite film has obvious ellipsoidal grains with distinct grain boundaries and better crystallinity. Moreover, the performance of the film after annealing in different atmospheres of the slow annealing route was improved compared with that of the rapid annealing route after annealing in different atmospheres. Simultaneously, by changing the annealing atmosphere of the composite film, the film exhibited better magnetic optical properties and coupling properties after annealing in oxygen. In addition, this study showed that the dielectric constant and residual polarization value of the film increase under the action of magnetic field and illumination, and the maximum photomagnetic dielectric response (3.19%) and photomagnetic response (1.58%) are observed in the annealed film under the oxygen atmosphere of the slow annealing regime, indicating that the magnetoelectric coupling effect of the film is improved under the action of applied light. • Under the slow annealing system, the composite films have grain boundaries and better crystallinity. • The properties of the films annealed under the slow annealing regime are good under different atmospheres. • Films show better magnetic, optical and coupling properties after annealing in oxygen. • The dielectric constant and residual polarization of the film increase under the action of magnetic field and illumination. • Large photomagneto-dielectric responses (3.19%) and photomagneto-electric responses (1.58%) were observed. [ABSTRACT FROM AUTHOR]

Multiferroic materials have attracted significant attention due to their potential to revolutionize logic and memory devices by reducing energy consumption or increasing information density. Barium monoferrite (γ-BaFe 2 O 4 or BaFeO) is a promising lead- and bismuth-free multiferroic material with a stuffed tridymite-like structure, exhibiting both ferroelectricity and antiferromagnetism at room temperature. BaFeO thin films with engineered grain orientation, composition, elastic strain, and magnetic interlayer couplings could open new avenues for novel devices. However, synthesizing the stoichiometric "1–2–4" phase in the BaO-Fe 2 O 3 system remains a challenge. This study focuses on the deposition of pure and crystalline γ-BaFe 2 O 4 thin films using the Pulsed Electron Deposition (PED) method. An analysis of the plasma plume revealed that two main mechanisms govern the dynamics of BaFeO deposition: a congruent ablation process occurring far from thermodynamic equilibrium and an incongruent low-energy evaporation process. The regions of the film with maximized ablative/evaporative ratios are free from the secondary Ba 2 Fe 2 O 5 phase, suggesting that the thermal evaporative contribution is the primary factor responsible for the out-of-stoichiometry composition. The influence of the substrate type on the structural properties of BaFeO films was also evaluated. It was confirmed that (h00)-oriented BaFeO tends to grow on amorphous quartz and polycrystalline Pt-coated quartz in the 700–800°C temperature range. Conversely, the growth on SiO 2 /Si leads to the preferential grain orientation along the (0k0) and (0kl) directions by increasing the temperature. These findings demonstrate the potential of PED for producing high-quality γ-BaFe 2 O 4 polycrystalline thin films. A fully heteroepitaxial (h00)-BaFeO/(111)-MgO system was even achieved by depositing on a single-crystal MgO substrate. This unprecedented result paves the way for utilizing such thin films in multiferroic applications, where phase purity, structural orientation, and defect-free structures can be exploited to enhance the magnetoelectric properties of the device. • γ-BaFe 2 O 4 (BaFeO) thin-films are deposited by Pulsed Electron Deposition (PED). • BaFeO growth involves congruent ablation and incongruent evaporation of the target. • Incongruent evaporation promotes the formation of Ba 2 Fe 2 O 5 secondary phase. • The substrate type has a significant influence on the structural properties of BaFeO thin films. • Pure and epitaxial (h00)-BaFe 2 O 4 films on (111)-MgO substrates are grown by PED. [ABSTRACT FROM AUTHOR]

• Mn 0.5 Zn 0.5 Fe 2 O 4 -PbZr y Ti 1-y O 3 multiferroic fluids were prepared by the ball milling method. • The polarization intensity of PbZr y Ti 1- y O 3 particles reaches its maximum of 2.55 μC cm−2. • Aa high dielectric constant of 4.6 and a saturation polarization intensity of 15.69 nC cm-2 were obtained. • All specimens present obvious magnetodielectric response. • The maximum longitudinal magnetoelectric coupling coefficient α E33 is 11.49 V cm−1 Oe-1. The Mn 0.5 Zn 0.5 Fe 2 O 4 -PbZr y Ti 1-y O 3 multiferroic fluids were prepared by the ball milling method, and the polarization intensities of PbZr y Ti 1-y O 3 particles on the magnetoelectric coupling (ME) effect were investigated. X-ray diffraction analysis (XRD) results indicate that the pure phase Mn 0.5 Zn 0.5 Fe 2 O 4 and PbZr y Ti 1-y O 3 particles (y = 0, 0.25, 0.5, 0.75, and 1) were successfully prepared. When y = 0.5, the polarization intensity of PbZr y Ti 1- y O 3 particles reaches its maximum of 2.55 μC cm−2. At this time, the Mn 0.5 Zn 0.5 Fe 2 O 4 -PbZr y Ti 1-y O 3 multiferroic fluids possess a high dielectric constant of 4.6 and a saturation polarization intensity of 15.69 nC cm−2. After applying the magnetic field, it shows a better magnetodielectric response (56.12 %), while the ferroelectric properties are also significantly improved. When the polarization intensity reaches its maximum value, the maximum longitudinal magnetoelectric coupling coefficient α E33 is 11.49 V cm−1 Oe-1. It provides a new approach to achieving the strong magnetoelectric coupling effect in multiferroic fluids. [ABSTRACT FROM AUTHOR]

• In this work, our creative points are in two aspects. One is the importance of inter-chain interaction is included in our model, that is not found in literature. • Another one is our reformed method, e. g. quantum Green's functional approach [25,26] by mapping spin operator into creative or annihilate field one. • A random phase approximation (RPA) is used for quasi-particle interactions to replace the Hartree-Fock one. • Our calculations show both spin transverse fluctuation and longitudinal fluctuation are equally importance in Green's function equation of motion. [ABSTRACT FROM AUTHOR]

Magnetic skyrmions can be generated, destroyed and driven to motion by electric spin currents in metals based on the spin transfer torque (STT) mechanism. However, the STT technique does not work in insulating materials because no electric currents can pass through. Fortunately, the magnetoelectric (ME) interaction that is present in multiferroic insulators makes it possible to manipulate magnetic skyrmions by applying electric fields. We have recently simulated ferroelectric (FE) skyrmionic crystals (or skyrmionic lattices so that skyrmionic crystals can be abbreviated as SkLs) formed in two-dimensional (2D) ferromagnetic (FM) multiferroic materials. Antiferromagnets are more abundant in nature. For this reason, we employ here a quantum computational method which we have developed in recent years to investigate the magnetic and polarized electric dipole textures of a 2D antiferromagnetic (AM) multiferroic system. Consequently, we observe in simulations that antiferroelectric (AE) and AM skyrmionic crystals can be generated simultaneously in a broad temperature and magnetic field phase region. Each of these AM and AE SkLs can be decomposed into two ferromagnetic or ferroelectric lattices which are FM or FE SkLs respectively, an FE skyrmion in one FE SkL is an electric dipole complex formed around the interstitial site of another FE SkL. The topological charges of the FE skyrmions are quantized to be integers, half integers or the odd multiples of ± 0. 25 especially within subsequently normally applied electric fields. In a strong external magnetic field, AE SkL and AM vortical crystal (VL) usually coexist. A subsequently applied perpendicular electric field is able to stabilize or destroy the both sorts of SkLs, and considerably elevate the coexisting temperatures of the AE SkL and AM VL textures even the electric field is very weak. • A quantum computational method is utilized here to simulate a multiferroic system. • Antiferroelectric and antiferromagnetic skyrmionic crystals appear simultaneously. • The two sorts of skyrmionic crystals can be manipulated by applied electric fields. • Antiferroelectric skyrmionic crystal can be decomposed into ferroelectric sublattices. • The topological charges of decomposed ferroelectric skyrmions are quantized. [ABSTRACT FROM AUTHOR]

The present work deals with the rare earth Erbium-based double perovskite. The chemical precipitation route was adopted followed by calcination at 700 °C for the synthesis of Er 2 FeCrO 6 (EFCO). The phase identification was performed using Rietveld refinement. Morphological analysis shows the formation of nanoparticles of EFCO having an average size of ∼15 nm. The M − H curve recorded at 10 K shows the weak ferromagnetic nature of the sample. Temperature variation of magnetization illustrates that EFCO nanoparticles undergo ferromagnetic transition at T c = 14 K. Temperature-dependent P-E studies display ferroelectric behaviour with a ferroelectric transition temperature (T CE = 453 K) which is beyond room temperature. The simultaneous existence of magnetic and electric orders may introduce EFCO as a new multiferroic oxide and a good alternative to the popular compound BiFeO 3. [Display omitted] • Nanostructured Er 2 FeCrO 6 has been synthesized using a solid-state route. • First-time multiferroic properties have been obtained with Er 2 FeCrO 6. • Weak ferromagnetic nature shows ferromagnetic transition at T c = 14 K. • P-E studies show the ferroelectric behaviour with a ferroelectric transition at 453 K. [ABSTRACT FROM AUTHOR]

This paper reports a systematic study of the electrical, multiferroic and magnetoelectric coupling properties of Co–Ti substituted Barium hexaferrites, having the chemical composition BaFe 12-2x Co x Ti x O 19 (x = 0–2.0; in steps of 0.5), synthesized using the sol gel auto-combustion method. X-ray Diffraction (XRD) studies and Rietveld refinement confirmed the successful incorporation of Co–Ti ions in the hexaferrite lattice with all the samples displaying Pb63/mmc space group single phase structure. Scanning Electron Microscope (SEM) images revealed the inhibition of crystal growth in a particular direction with Co–Ti substitution. The conduction mechanisms of the samples were analysed from the conductivity measurements and were found to follow Jonschers power law. The complex impedance spectroscopy analysis and the Cole-Cole plot fitted diagrams of the samples indicated the enhancement of bulk resistivity and grain boundary resistivity with substitution. Saturation magnetizations of the substituted samples decreased and were ascribed to the replacement of Fe ions by Co–Ti ions at different crystallographic sites. The observed reduction in anisotropy constant indicated the disturbance in the magnetic axis. The multiferroic nature of the substituted samples at room temperature was confirmed from the soft ferroelectric loops. Room temperature magnetoelectric coupling coefficient was found to be largely enhanced with substitution, achieving an exceptionally high value of 182mV/cmOe for the x = 1.5 sample. This may prove useful for potential use in emerging device applications as a single phase room temperature multiferroic material. • Co–Ti substituted Barium hexaferrite was synthesized using the sol gel auto-combustion method. • XRD and Rietveld refinement confirmed the formation of single phase structure with P63/mmc space group. • Resistance of the substituted samples were enhanced upto 3 orders in magnitude. • Ferroelectric loops were obtained confirming the multiferroic nature of the substituted samples. • A large magnetoelectric coupling coefficient of 182mV/cmOe was obtained in one of the substituted samples. [ABSTRACT FROM AUTHOR]

• we have synthesized Ni 0.5 Co 0.5 Fe 2 O 4 (NCFO) and BaTiO 3 (BTO) core–shell (12 % NCFO − 88 %BTO) multiferroic nanopowder by hydrothermal method and sol–gel method, respectively. • The core–shell like morphology is clearly observed in the SEM analysis. • The sample 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 W rec (17.78 mJ/cm3). • From the magnetic measurements it is revealed that the sample shows lower saturation magnetization (1.33 emu/g) with coercivity (430 Oe) and magneto-crystalline anisotropy of (595.7 erg/g). • A moderate magnetoelectric coefficient of 18.34 mV/cm*Oe is observed on the higher field side than the value obtained on the lower field side (32.62 mV/cm*Oe). In this report, we have synthesized Ni 0.5 Co 0.5 Fe 2 O 4 (NCFO) and BaTiO 3 (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 W rec (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. [ABSTRACT FROM AUTHOR]

Adhesion control is a critical aspect of various applications, from industrial adhesion devices to the locomotion of insects on ceilings and walls. Multi-ferroic materials, which encompass mechanical, electrical, and magnetic properties, offer approaches for reversible adhesion control. This study presents a comprehensive theoretical framework for adhesive contact in multi-ferroic composite materials when subjected to axisymmetric rigid indenters with arbitrary profiles. We analytically derive the physical fields for various contact models, including Hertz contact, Johnson–Kendall–Roberts (JKR), and Maugis–Dugdale (MD) adhesive models. The obtained energy release rates indicate that the electric and magnetic potentials can modulate adhesion strength. The Griffith energy balance relation is employed to derive the indentation forces and penetration depths, which can be extended to a range of common indenters. Notably, the classical approximations fail when using small spherical indenters, but the study provides valid alternatives. The influence of amplitude and wavelength on contact behavior is explored, with greater effects observed for larger or smaller values. For cosine-shaped indenters, equivalence to flat-ended cylindrical punches is established under specific conditions. The study also reveals that the power indices for power-law-shaped indenters change the influence of electric and magnetic potentials on pull-off forces. These findings provide a theoretical fundament associated with the biomimetic and artificial adhesive systems and the modern testing techniques. • The general theory for an indenter with arbitrary profiles is developed. • The physical fields for the Hertz, JKR and MD model are analytically obtained. • The electric and magnetic potentials can modulate adhesion strength. • The physical quantities for a range of common indenters are derived. • Influence of geometrical shape on the contact behaviors is numerically quantified. [ABSTRACT FROM AUTHOR]

Structural analysis, spectroscopic studies and multiferroic properties of Zn 1- x Ni x O (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15) nanoparticles are reported here. Ni-doped ZnO nanoparticles were synthesized through a simple chemical growth route using hydroxyoxalate type materials. The hexagonal wurtzite structure of prepared compounds has been ascertained through X-ray diffraction. High Resolution Transmission Electron Microscopy (HRTEM) reveals the particle size and lattice growth direction of the nanoparticles. The expected doping concentration of nickel was confirmed by Energy Dispersive X-ray (EDX) spectroscopy. The excitonic peaks observed from absorption spectra of the prepared nanoparticles exhibit blue shift for nickel doping. Ni-doped ZnO explore superior photocatalytic response and are controlled by three factors: band gap, crystallite size and surface defect. To be specific, 12 % Ni doping results in 7.8 times increase in the photocatalytic degradation efficiency. The samples exhibit characteristic P -E and M − H loops. The obtained remnant polarization for 9 % and 15 % Ni doping are 9 × 10−3 and 6 × 10−3 μC/cm2 respectively. The multiferroicity perceived in the synthesized Ni-doped ZnO nanoparticles with the ME coefficient at around 1.1mV/cm-Oe have important application potentiality in electromagnetic coupled devices. • Ni-doped ZnO nanopowders for tuning the physical properties as multiferroicity. • Prominence of absorption in UV-VIS due to exciton-exciton collision. • Superior sunlight-driven photocatalytic effect of Ni-doped ZnO nanoparticles. • Signature of multiferroic behavior in nickel doped ZnO materials. • Magnetic and magnetoelectric properties of nickel doped ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

X-ray absorption spectroscopic (XAS) and Mössbauer investigations have been carried out to obtain information on the local environment of Fe ions in Pb 2 FeSbO 6 (PFS) samples with different degree of the Fe3+ and Sb5+ ordering. Analysis of Mössbauer spectra shows, that the fraction of doublet component in the spectrum of the disordered PFS sample is significantly larger, than that of the ordered one, however singlet component still persists, indicating the presence of the compositionally ordered regions. The Fe K -spectrum absorption for the ordered PFS sample exhibits the lowest pre-edge intensities, indicating that Fe position is close to the oxygen octahedron center. The higher amplitude of this peak for the disordered sample provides evidence for structural distortions, involving Fe displacement off the octahedra centers. Additional support to this conclusion provides the structure of absorption spectra, which gave substantially higher Debye-Waller factor of Fe–O shell for disordered sample as compared to the ordered one. [ABSTRACT FROM AUTHOR]

• The influence of different Nd and PbTiO 3 compositions on the magnetic and magnetoelectric features of (1-y)Bi 1-x Nd x FeO 3-y PbTiO 3 solid solutions, were investigated. • The degree of magnetization is found to increase with increasing Nd doping due to the modification in spiral spin structure and by affecting Fe-O-Fe bending's. • The splitting of the ZFC and FC branches in M-T plots with increasing Nd doping indicate the change of antiferromagnetic to ferromagnetic behavior of solid solutions which is also confirmed by M-H characterization of solid solutions. • The splitting of the ZFC and FC branches in M-T plots with increasing Nd doping indicate the change of antiferromagnetic to ferromagnetic behavior of solid solutions which is also confirmed by M-H characterization of solid solutions. • The splitting of the ZFC and FC branches in M-T plots with increasing Nd doping indicate the change of antiferromagnetic to ferromagnetic behavior of solid solutions which is also confirmed by M-H characterization of solid solutions. Magneto-electronic devices applications of room-temperature multiferroics have been made possible by recent developments. But the potential use of pure BFO in multifunctional devices is constrained by its antiferromagnetic nature and need substitution-induced modification to improve magnetic and magnetoelectric properties. In the present paper, attempt has been made to improve the magnetic and magnetoelectric properties of the BiFeO 3 -PbTiO 3 solid solution by incorporating Bismuth cation with Lead(II) ion and Ferric cation with Titanium cation into the formulation of Nd doped,(1- y)Bi 1- x Nd x FeO 3 - y PbTiO 3 where x = 0.05,0.10,0.15,0.20 and y = 0.1, 0.2,0.3 and 0.4. The impact of different PbTiO 3 and Nd compositions on magnetoelectric and magnetic characteristics of solid solution has been investigated. The results showed that, degree of magnetization continuously increases with increasing Nd doping by affecting Fe-O-Fe angles. However, the magnetization drops as the volume of PbTiO3 rises, that may be attributed to a rise in the tetragonal phase of solid solutions. The improvement of the magnetoelectric coupling coefficient and change of antiferromagnetic behaviour to ferromagnetic behaviour of solid solutions has been observed with increasing Nd doping. This enhance the ferromagnetic behaviour of the compound. [ABSTRACT FROM AUTHOR]

The primary order parameter of hybrid improper ferroelectricity (HIF) is not spontaneous polarisation but nonpolar modes such as oxygen octahedral rotations (OORs), antipolar, or even Jahnâ€"Teller distortions; therefore, the HIF mechanism may be applied as an effective pathway to tune electronic bandgaps, control orbitals, and create multiferroicity. Most of the current experimental research on HIF is focused on layered perovskite oxides; therefore, this review focuses on the recent progress of experimental studies on HIF materials with the Ruddlesdenâ€"Popper (Râ€"P) and Dionâ€"Jacobson (Dâ€"J) structures. Experimental research on double-layered Râ€"P oxides is included, and the linear relationship between the Curie temperature and tolerance factor has been established. Moreover, the coexistence of polar and weak ferromagnetic phases has been observed in iron-based double-layered Râ€"P oxides at room temperature. The recent discovery of ferroelectricity in A-site cation-ordered triple-layered Râ€"P oxides has significantly expanded the HIF field. HIF has also been confirmed in caesium- and rubidium-based double-layered Dâ€"J oxides, and complex OOR modes have been observed in Dâ€"J oxides. Although significant progress has been achieved for HIF materials in layered perovskite oxides, extensive research is required to reveal the mysteries of HIF and to create single-phase multiferroics in HIF materials. [ABSTRACT FROM AUTHOR]

The use of lead-free ceramic film materials with positive temperature coefficient of resistivity (PTCR) is widespread in temperature heaters and sensors in micro-electromechanical systems. In this research, the out of plane transport properties of the BiFeO3 (BFO) films have been studied. Surprisingly, PTCR was found in the BFO ceramic films due to the strongly correlated interaction between the multiferroic material BFO and the superconductor YBCO perovskite oxides. To our knowledge, this is the first report on the PTCR effect of BFO films. The BFO/YBCO interface and the bulk conductivity of BFO are important for the PTCR effect, as they make it possible to compare the transport properties of Au/BFO/YBCO- and YBCO/BFO/YBCO-type structures. PTCR was observed in Au/BFO/YBCO at a bias voltage of more than 2 V, but not in the YBCO/BFO/YBCO, even with a 40 V bias voltage. PTCR was found after BFO breakdown of a YBCO/BFO/YBCO capacitor. This indicated that the conductivity of BFO is critical for PTCR. The dependence of PTCR on the superconducting transition temperature illustrates that a cooper-pair can be injected into BFO. Our work presents a method by which to produce a lead-free ceramic film material with PTCR. [ABSTRACT FROM AUTHOR]

Multiferroic is the future of the next generation memory devices; because of its advantages over the single-phase ferroelectric and ferromagnetic memory systems. In conventional ferroelectric memory system fatigue effect lowers the storage capacity. Other side high magnetic energy is essential for writing the data in ferromagnetic-based memory system. Considering these facets and taking environmental issue in the account we developed lead-free Na0.5Bi0.5TiO3 (NBT)–CoFe2O4 (CFO) multiferroic system via two wet chemical methods. To check the feasibility of the system for device application various physical measurements were carried out. The structural analyses have been done by XRD, FTIR and FESEM which confirm the coexistence of bi-phase in these composites. The dense microstructure was observed for composite sample with highest CFO concentration. In comparison to pure ferrite phase, the composite exhibit low leakage current density, high dielectric constant with low dielectric losses. Interestingly, the CFO affected the phase transition temperature of the NBT as evidenced by the dielectric behaviour as a function of temperature. Also, multiferroic studies were influenced by the content of CFO/NBT phases in composite system. Furthermore, the highest value of ME coupling (~ 64 μV/Oe-cm) was observed for the 50CFO/50NBT composite system. [ABSTRACT FROM AUTHOR]

Multiferroic composites are getting the spotlight in scientific community because of their versatility in various room temperature applications including the spintronics devices, actuators, sensors, and other multifunctional memory devices. Multiferroic 4-phase polymer-ceramic composites in the form of (1 − x)[0.9(0.3CoFe2O4-0.7BiFeO3)-0.1Pb(Zr0.52,Ti0.48)O3]-xPVDF (BFO-CFO-PZT/PVDF) have been synthesized by a sol–gel and hot-pressed combined low-temperature process. The impact of the PDVF addition with different volume on the structure, morphology, ferroelectric, dielectric, magnetic, and magnetoelectric features are investigated. XRD analysis shows the presence of 4 distinct phases of CFO, BFO, PZT, and PVDF. The dielectric loss and remanent polarization were found to reduce proportionally to the addition of PVDF. In the mean time, the magnetoelectric coupling retain similar large values irrelevant with the addition of PVDF. It is then concluded that the introduction of PVDF polymer matrix is able to overcome the flaws of BFO-CFO-PZT composite while retain its exceptional multiferroic properties. [ABSTRACT FROM AUTHOR]

Methods for controlling (by magnetic field, changing temperature, and optical pumping) the properties of nanoregions forming due to self-organization during phase separation in Eu0.8Ce0.2Mn2O5 multiferroics are studied. Such nanoregions are superlattices (semiconductor heterostructures). The dynamically equilibrium states of superlattices (their long-lived ground states) are formed during cycling under magnetic field. Such states of superlattices are electrically neutral and consist of ferromagnetic layers. A set of ferromagnetic resonances from superlattices layers make it possible to distinguish the states of superlattices. The optical pumping of various powers allows controlling both the magnetic and electrical properties of superlattices. [ABSTRACT FROM AUTHOR]

Multiferroic solid solution of (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3, and BiFeO3, with stoichiometry 1−x(0.98BCZT-0.02BFO)xCuO; (0.0 ≤ x ≤ 4.0 wt %) were prepared via mixed oxide solid-state reaction (MOSSR) route sintered at 1075 °C. All samples were analyzed by X-ray diffraction, Fourier transform infrared spectrometer, field emission scanning electron microscopy, and impedance spectroscopy, respectively. XRD results confirmed the formation of a stable solid solution in pure composition with tetragonal symmetry, while the addition of CuO shows tetragonal to pseudocubic transformation. Absorption peaks in FT-IR spectra confirmed the presence of phases. SEM study revealed that dopant addition improved densification with the evolution of coarse grains. High-temperature impedance studies suggested that both grain and grain boundaries contribute to the impedance, while the addition of CuO promotes change defects at grain boundaries. Moreover, negative thermal coefficient resistance (NTCR) behavior with thermally activated dielectric relaxation is observed which makes these compositions suitable for thermal sensor applications. [ABSTRACT FROM AUTHOR]

0.9Bi1-xNdxFeO3 − 0.1PbTiO3 solid solution with x = 0.05, 0.10, 0.15 and 0.20 were success fully synthesized by the standard solid-state reaction method. The effect of Nd3+ion substitution on structural, micro structural, ferroelectric, magnetic and dielectric properties of 0.9BiFeO3-0.1PbTiO3 have been investigated. The XRD analysis for the samples under study revealed distorted rhombohedral structure with R3C space group. 0.9Bi1-xNdxFeO3 − 0.1PbTiO3 i.e. (BNFPT)x with x = 0.05, 0.10, 0.15 and 0.20 compounds crystallized as single-phase materials with the same structure as the parent BiFeO3 compound. The SEM study revealed the uniform grain scattering for all prepared samples. Raman spectroscopy showed disappearance of some Raman modes indicated a structural phase transition with substitution of Nd dopants at Bi site and also confirmed the distorted rhombohedral perovskite structure of (BNFPT)x compounds with R3c symmetry. Dielectric measurements reveals that, around Neel temperature, all the samples exhibit magneto-electric coupling and also improved dielectric properties with addition of dopants in BiFeO3(BFO) compound. All the prepared samples exhibit weak ferro-magnetic character at room temperature. However, the variation in linear behavior and enhancement in magnetization is found at 5 K which shows gradual increase in remnant magnetization from 0.00785 emu/g to 0.37513 emu/g with increase in Nd doping for all (BNFPT)x samples. Nd doping reduces leakage current by three orders of magnitude, from 10−4 to 10−7. Ferroelectric study revealed the pinning effect in hysteresis loops with low remnant polarization and coercive field which can be related to the energy storage performance of the samples. [ABSTRACT FROM AUTHOR]

The study of the magnetic dynamics of some magnetic crystals with 3d ions having different symmetries reveals phase separation domains. They turn out to be similar to phase separation domains in RMn2O5 multiferroics with charge ordering. This apparently occurs because flexoelastic magnetoelectric inhomogeneities with an increased electron density appear in domain walls of the studied crystals; this electron density changes the charge composition of ions in such walls. In this case, change in the valences of 3d ions at which their charge ordering occurs becomes energetically favorable. As a result, phase separation similar to that formed in RMn2O5 multiferroics appears in the domain walls of these crystals. [ABSTRACT FROM AUTHOR]

Multifunctional materials with high magnetic, electrical, and magnetoelectric (ME) characteristics play an important role in development of data storage devices. Herein, multi-phase ($0.95- x$)Ba0.9Ca0.1TiO3 (BCT)-0.05Na0.5Bi0.5TiO3 (NBT)- $x$ CoFe2O4 (CFO) ceramics were prepared by a two-stage mechanochemical activation technique. The objective of this study is to develop a multifunctional material with improved multiferroic characteristics. The structural analysis by the Rietveld method shows the presence of heterogeneous structure without any impurity phase. The incorporation of CFO in 0.95BCT-0.05NBT has resulted in significant improvement in magnetic and ME characteristics without significantly hampering the electrical properties. The sample with $x =0.11$ has shown high saturation magnetization of 8.26 emu/g along with moderately high ME coefficient of 5.411 mV/cm $\cdot $ Oe. In addition, the energy storage performance of all the studied samples has also been investigated and the optimized sample $x =0.11$ presents a large discharge energy density of 2.249 J/cm3 and moderately high energy efficiency of 63.8% at 388 kV/cm. The results obtained in this work suggest a significant influence of CFO substitution on the magnetic characteristics of BCT-NBT ceramics, which subsequently indicate their potential applications in spintronics, magnetic memory storage, and electrical energy storage devices. [ABSTRACT FROM AUTHOR]

Neutron diffraction study of Nd0.8Tb0.2Mn2O5 single crystal has been performed using both non-polarized and polarized neutron diffraction. Low temperature set of magnetic satellites corresponding to two magnetic ordered phases witnesses about the magnetic phase separation. One of those phases with propagation vector $k_{1} = (0.5\,\,0\,\,k_{z1})$ bears features of magnetic order in TbMn2O5 with ordering temperature $\text {TN} \approx 37$ K. Another one with propagation vector $k_{2} = (0.5\,\,0\,\,k_{z2})$ and Neel temperature of $\text {TN2} \approx 30$ K has a great similarity to magnetic order of NdMn2O5. Both of them are chiral at low temperatures. Difference in chiral domain population could be controlled by the external electric field of few kV/cm. Two additional magnetic phases with $k_{3,4} = (0.5\,\,0\,\,k_{z3,4})$ were observed in the short intermediate temperature range 20–28 K. Significant temperature hysteresis of 6–8 K for all magnetic phases was observed in dependence of cooling/heating temperature evolution. Results are discussed in the frame of competing magnetic interactions. [ABSTRACT FROM AUTHOR]

Ceramic samples of BiFeO3-based perovskite solid solutions with the highly ordered complex perovskites PbFe 1 / 2 Sb 1 / 2 O3(PFS) and SrFe 1 / 2 Sb 1 / 2 O3 (SFS) were obtained using high-pressure synthesis at 4–6 GPa. Mössbauer studies revealed that BiFeO3-SFS compositions are characterized by a larger compositional inhomogeneity as compared to BiFeO3-PFS ones. In line with this result, concentration dependence of the magnetic phase transition temperature T N for BiFeO3-SFS compositions is close to the T N (x) dependence for BiFeO3solid solution with disordered perovskite PbFe 1 / 2 Nb 1 / 2 O3(PFN). In contrast to this T N (x) dependence for BiFeO3-PFS compositions nicely follows the theoretical T N (x) dependence calculated for the case of the ordered distribution of Fe 3 + and non-magnetic Sb 5 + ions in the lattice (chemical ordering). [ABSTRACT FROM AUTHOR]

This work presents the results of studying the electrophysical properties of the YCu 0. 1 5 Mn 0. 8 5 O3 solid solution in the range of temperatures of T = 26–400 ∘ C and frequency range of f = 102–105 Hz. A model description of the revealed dispersion of dielectric parameters in the material is made. The nonclassical modified Havriliak–Negami model written for complex electrical conductivity was used as an approximation model. It is shown that the application of this model almost exactly describes the frequency behavior of the dielectric constant ′ / 0 (f) , the dielectric loss tangent tg δ (f) as well as the real and imaginary parts of complex conductivity γ ′ (f) and γ ′ ′ (f). The results of this work are an important step in identifying the opportunities and understanding the applications of this model. [ABSTRACT FROM AUTHOR]

Perovskite materials based on BiFeO3‐PbTiO3 (BFPT) solid solutions are promising for various applications thanks to the extremely large spontaneous polarization (Ps) and existence of multiferroic morphotropic phase boundary. For applications in piezoelectric and memory devices, complete switching of Ps is needed, which is hard to achieve practically. In this work, a simple modified mixed‐oxide reaction method is developed allowing to prepare Dy‐ and Sm‐modified BFPT ceramics with significantly improved properties. The MPB compositions demonstrate well‐saturated ferroelectric hysteresis loops with large switchable remanent polarization of 60 µC cm−2 and enhanced piezoelectric properties with a large‐signal piezoelectric coefficient d33* = 214 pm V−1 and a direct piezoelectric coefficient d33 = 128 pC N−1, which is one and a half times larger than the best d33 value reported for the BFPT ceramics so far. The Curie temperature reaches 539 °C, suggesting a potential for high‐temperature applications. The domain structure is studied by piezoresponse force microscopy. It is found that the enhanced dielectric/piezoelectric properties are mainly due to polarization rotation/extension (intrinsic) mechanism, while the extrinsic contributions of the interphase and domain walls are virtually absent. The strategies for improvement of properties of BFPT and related materials are proposed. [ABSTRACT FROM AUTHOR]

The materials which exhibit coupled electric, magnetic, and structural order parameters, yield simultaneous effects of ferroelectricity, ferromagnetism, and ferroelasticity are referred as multiferroics. Multiferroic properties like ferromagnetism and ferroelectricity of BiFeO3 (BFO) have been reported to be enhanced by forming solid solution with BaTiO3 (BT) designated by BFO-BT. In the present investigations, a solid solution of (1-x)BFO-xBT (x = 0, 0.05, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.85, 0.90, and 1.0) single phase have been synthesized by solid state ceramic route. Structural, magnetic and electrical properties of single phase solid solution of BFO-BT have studied in detail to understand their multiferroic properties. In powder X-ray diffraction confirms the formation of single phase solid solution of BFO-BT. The structural change from rhombohedral to tetragonal is observed with MPB. Decrease in distortion of rhombohedral lattice is observed with BaTiO3 addition. All the samples show weak ferromagnetic behavior at room temperature due to a residual magnetic moment caused by canting spin magnetic structure having low coercivity and high saturation magnetization. The polar lattice of BiFeO3/BaTiO3 is retained throughout the solid solutions as observed from the polarization study. The ferroelectricity is observed throughout the solid solutions. [ABSTRACT FROM AUTHOR]

Solid state reaction was employed to synthesize the Bi1−xSrxFe1−xMnxO3 (x = 0.05, 0.10, 0.20, 0.25) ceramic materials. XRD reveals the single-phase rhombohedral structure with R3c space group of the prepared materials. The FTIR spectra have been used to calculate the Fe–O bond length. The UV–Visible diffuse reflectance spectra was used for the calculations of the band gaps, which are found to decrease from 2.02 to 1.83 eV on increasing the Sr and Mn co-doping in BFO. P-E loops were recorded for the samples to determine ferroelectric nature at various applied fields. M-H hysteresis loops show a significant change in remnant magnetization (Mr), saturated magnetization (Ms) and coercive field, (Hc) with Sr–Mn substitution in BiFeO3. From FESEM images revealed agglomerated particles in the samples investigated and an increase in grain size is observed with increase in co-doping in BiFeO3. Out of all the prepared samples, Bi0.90Sr0.10Fe0.90Mn0.10O3 with modified values of multiferroic parameters among the Bi1−xSrxFe1−xMnxO3 (x = 0.05, 0.10, 0.20, 0.25) may be useful as a promising multiferroic material for applications of actuators, sensors and multistate memory devices. [ABSTRACT FROM AUTHOR]

For the investigation of the exchange bias effect and magneto-optical properties of Bi0.8Re0.2(Re = Nd and Sm)FeO3 (BNFO and BSFO) nanofibers were synthesized via the electrospinning technique. The crystal structure was changed from rhombohedral phases of space group R3c before undoping shift to orthorhombic phases of space group Pbam and Pnma after doping of Nd3+ and Sm3+ ions, respectively, by the Rietveld refinement results. Analysis of the magnetic hysteresis loops demonstrated that the remanent magnetization especially coercivity of BNFO and BSFO nanofibers at 10 K and 300 K exhibited obviously variation, which was attributed to the lower temperature suppressed the fluctuation of magneto-caloric and valence state. The XPS and EDS results displayed the Nd3+ and Sm3+ ions were successfully doped into BFO nanofibers. Meanwhile, the lattice distortion induced the suppression of antiferromagnetic ordered spin modulation, which played an important role to enhance the magnetic properties. It was observed that the exchange bias effect (HEB) of BNFO nanofibers was higher than those of BSFO nanofibers. UV–vis spectra measurements revealed the band gap of BNFO and BSFO nanofibers was 1.87 eV and 1.85 eV, respectively, and the absorption edges of BSFO nanofibers occurred a slightly red shift. The MO degradation rates of BNFO and BSFO nanofibers reached about 89.4% and 78.6%, respectively, which could be a potential candidate in photo-electron devices and the semiconductor industry. [ABSTRACT FROM AUTHOR]

Multiferroics are a unique class of materials where magnetic and ferroelectric orders coexist. The research on multiferroics contributes significantly to the fundamental understanding of the strong correlations between different material degrees of freedom and provides an energy‐efficient route toward the electrical control of magnetism. While multiple ABO3 oxide perovskites are identified as being multiferroic, their magnetoelectric coupling strength is often weak, necessitating the material search in different compounds. Here, the observation of room‐temperature multiferroic orders in multi‐anion SrNbO3−xNx thin films is reported. In these samples, the multi‐anion state enables the room‐temperature ferromagnetic ordering of the Nb d‐electrons. Simultaneously, ferroelectric responses that originate from the structural symmetry breaking associated are found with both the off‐center displacements of Nb and the geometric displacements of Sr, depending on the relative O‐N arrangements within the Nb‐centered octahedra. The findings not only diversify the available multiferroic material pool but also demonstrate a new multiferroism design strategy via multi‐anion engineering. [ABSTRACT FROM AUTHOR]

Electron‐doped La0.9Hf0.1MnO3 thin films are epitaxially integrated onto 0.7Pb(Mg1/3Nb2/3)O3−0.3PbTiO3 single‐crystalline ferroelectric substrates to construct multiferroic heterostructures. By applying a light field and not just changing temperature, the relative magnitude of the electric‐field‐generated lattice strain effect and interfacial charge effect is identified to be controllable. Moreover, the electric field can enhance the photoresistance effect by 26%. This, accompanied by light‐tunable electroresistance effect, intimate interaction between the electric‐field‐generated and light‐generated effects is demonstrated. Herein, a route to achieve low‐power multifield (light and electric field) control of electronic transport in electron‐doped perovskite manganites is provided. [ABSTRACT FROM AUTHOR]

Magnetoelectric materials that allow magnetic-field control of electric polarization are promising candidates for high-density data storage and spintronic devices. In this paper, the ferroelectric, magnetic, and magnetoelectric properties of NiFe2O4/PbZ0.5T0.5O3, CoFe2O4/PbZ0.5T0.5O3, NiFe2O4/PbZ0.5T0.5O3/CoFe2O4, and NiFe2O4/PbZ0.5T0.5O3/NiFe2O4 heterostructures have been carried out using the Monte Carlo simulation in the framework of the Heisenberg model. The effects of the temperature on magnetization, electric polarization, and their susceptibilities were examined. The calculated interfacial magnetoelectric coupling interaction Jme for NiFe2O4/PbZ0.5T0.5O3 and CoFe2O4/PbZ0.5T0.5O3 interfaces permitted to predict the magnetoelectric voltage coefficient for these heterostructures and controlling the polarization via a magnetic field. Interestingly, a high magnetoelectric voltage coefficient of 650 and 1405 mV cm−1 Oe−1 was predicted in NiFe2O4/PbZ0.5T0.5O3/CoFe2O4 and NiFe2O4/PbZ0.5T0.5O3/NiFe2O4, respectively. Moreover, the effect of Jme on M-H and P–H hysteresis loops and the magnetoelectric voltage coefficient was studied. [ABSTRACT FROM AUTHOR]

The effect of grain size was not fully explored in composites containing ferroelectric and magnetic phases including the independent properties of each phase. Aiming to study the dependence of ferroic and multiferroic properties with average grain size in composites this work reports preparation method and electric, magnetic and magnetoelectric properties of particulate composites with distinct combination of grain size of each phase. A new sintering method was applied to prepare a group of samples with distinct configuration of grain size distribution. With this method it was possible to densify ceramics avoiding grain growth using spark plasma sintering. It was observed that the all ferroic and multiferroic properties were correlated with the setup of grain size of each phase in the composite, by example the dependence of magnetic properties with the electric phase grain size. Besides it was noticed that is possible to improve magnetoelectric coefficient by changing grain size of both phase, even inducing the self-biased effect by decreasing the grain size of the ferroelectric phase. [ABSTRACT FROM AUTHOR]

This Perspective highlights the promise of magnetoelectrics for potential memory and other applications, e.g., sensors and energy harvesters, noting the challenges posed by current magnetoelectric materials and potential solutions to these challenges. While single phase materials do give strong enough magnetoelectric coupling, interface coupled composite systems show unique advantages. From the viewpoint of these composite materials and devices, we review the current status and present an outlook on possible future research directions, with particular emphasis on 3-1 type nanocomposites which are arguably the most promising composite form. [ABSTRACT FROM AUTHOR]

Beside playing a keystone role in spin-field-effect transistor, electrical control of spin transport is also of fundamental and practical importance for many other spintronic devices due to the advantages of energy efficiency and versatility. In this work, we demonstrate a significant electrical modulation of spin transport in the PMN-PT/LiFe5O8/Pt heterostructures. The key spin transport parameters, including the spin Hall angle, spin diffusion length, and spin mixing conductance, were extracted through the thickness dependence of spin Hall magnetoresistance. It is found that the spin Hall angle decreases with the decrease in temperature, while the spin diffusion length keeps invariant with temperature, revealing the dominance of D'yakonov–Perel' type spin transport in LiFe5O8/Pt. Remarkably, by applying the electric field onto the piezoelectric PMN-PT substrate, the spin Hall angle of Pt can be modulated 28% and exhibits a nonvolatile hysteresis relationship with the applied electric field, which primarily originates from the modulation of Pt resistivity induced by the strain coupling through the ferroelastic domain switching of the ferroelectric PMN-PT substrate. Our results elucidate the spin transport characteristics in PMN-PT/LiFe5O8/Pt heterostructures and pave the way toward novel spintronic devices with electrically tunable spin current generation and transport processes. [ABSTRACT FROM AUTHOR]

The paper reviews scientific studies on the synthesis and properties of magnetic nanocrystals based on ferrites and diluted magnetic semiconductors that have been reported mostly in the past 10–15 years. New data on controlling the characteristics of these materials by doping and practical applications are discussed. [ABSTRACT FROM AUTHOR]

Multiferroic materials composed of ferromagnetic and ferroelectric components are interesting for technological applications due to sizable magnetoelectric coupling allowing the control of magnetic properties by electric fields. Due to being compatible with the silicon-based technology, HfO2-based ferroelectrics could serve as a promising component in the composite multiferroics. Recently, a strong charge-mediated magnetoelectric coupling has been predicted for a Ni/HfO2 multiferroic heterostructure. Here, using density functional theory calculations, we systematically study the effects of the interfacial oxygen stoichiometry relevant to experiments on the magnetoelectric effect at the Ni/HfO2 interface. We demonstrate that the magnetoelectric effect is very sensitive to the interface stoichiometry and is reversed if an oxidized Ni monolayer is formed at the interface. The reversal of the magnetoelectric effect is driven by a strong Ni−O bonding producing exchange-split polarization-sensitive antibonding states at the Fermi energy. We argue that the predicted reversal of the magnetoelectric effect is typical for other 3d ferromagnetic metals, such as Co and Fe, where the metal-oxide antibonding states have an opposite spin polarization compared to that in the pristine ferromagnetic metals. Our results provide an important insight into the mechanism of the interfacial magnetoelectric coupling, which is essential for the physics and application of multiferroic heterostructures. [ABSTRACT FROM AUTHOR]

GdFexMn1-xO3 (x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) nanoparticle series was synthesised using sol–gel auto-combustion technique. Rietveld refinement of x-ray diffraction (XRD) patterns revealed that all samples are crystallized in a single phase with (Pnma) space group No.62. The FC–ZFC measurements showed an increase in the antiferromagnetic (AFM) to paramagnetic (PM) transition Néel temperature (TN) with the increase of Fe3+ content, reaching a value of 344 K at 50% of Fe doping. The inclusion of Fe also induced spin reorientation temperature (TSR) at x = 0.5 and x = 0.7. 57Fe mössbauer spectroscopy measurements were carried out at room temperature (RT⁓295 K) and liquid nitrogen (LN⁓78 K) temperature. Both RT and LN mössbauer spectra were fitted with paramagnetic doublet for low Fe content (x < 0.5), whereas for higher Fe content (x > 0.5), the spectra were fitted with magnetic sextet. Isomer shift values confirms the dominance of Fe in its high oxidation state (Fe3+). [ABSTRACT FROM AUTHOR]

BiMnO3 (BMO) ceramics was synthesized and sintered by mechanochemical method. Effect of sintering on the structure and multiferroic was investigated by XRD, FESEM, HRTEM, ferroelectric and magnetic study. These studies synchronously exhibited the formation of distinct nanostructured monoclinic perovskite (C2 space group) phase with crystallite size range from 5 to 40 nm. The dielectric study revealed a significant dependence of εr and tanδ with the change in sintering temperature. P-E loop and magnetization studies revealed a trend of increase in Pr (0.396 μC/cm2 to 0.50 μC/cm2) and decrease in Ms (0.125 to 0.085) respectively with the rise in sintering temperature. [ABSTRACT FROM AUTHOR]

Hexagonal rare‐earth ferrites (h‐RFeO3) have attracted much scientific attention due to their room‐temperature multiferroicity. However, it is still a hard job to obtain h‐RFeO3 bulk materials because of the meta‐stability of such hexagonal phase, and the evaluation of room‐temperature ferroelectric and magnetoelectric characteristics in such materials is also a challengeable issue. In the present work, Yb1−xInxFeO3 ceramics with the stable hexagonal structure were obtained by introducing chemical pressure, where the unique ferroelectric domain structures of sixfold vortex combined with tenfold vortex with a typical size of ~400 nm were determined. Symmetry of the present system evolved from centrosymmetric orthorhombic Pbnm (x = 0–0.4) to non‐centrosymmetric hexagonal P63cm (x = 0.5 and 0.6) with a ferroelectric polarization up to 3.2 μC/cm2, and finally to centrosymmetric hexagonal P63/mmc (x = 0.7 and 0.8). The Curie point decreased monotonically from 723 K to a temperature below room temperature with increasing x, and the antiferromagnetic phase transition above room temperature was determined for all compositions. Meanwhile, a large linear magnetoelectric coefficient (αME) up to 0.96 mV/cm Oe was obtained at room temperature, and this indicated the great application potential for magnetoelectric devices. [ABSTRACT FROM AUTHOR]

The well‐known ferromagnetic oxide, NiFe2O4, was studied as a potential candidate for room‐temperature Type II magnetoelectrics. A spin canting as one of the essential requirements for Type II multiferroics was induced by breaking the stoichiometry, that is, intentionally subtracting Fe ions. We observed that Fe ions were first subtracted exclusively from the tetrahedral sites, leading to an increase in the magnetoelectric coupling owing to an increasing degree of spin canting. The enhancement in the magnetoelectric coupling culminated beyond the subtraction level of ~30 at.%, at which Fe ions started to be removed from the octahedral sites. Alongside, we observed that the subtraction of Fe ions gives rise to a ferroelectricity due to the formation of defect complexes that establish an internal bias field. [ABSTRACT FROM AUTHOR]

Multiferroic materials with flexibility are expected to make great contributions to flexible electronic applications, such as sensors, memories, and wearable devices. In this work, super‐flexible freestanding BiMnO3 membranes with simultaneous ferroelectricity and ferromagnetism are synthesized using water‐soluble Sr3Al2O6 as the sacrificial buffer layer. The super‐flexibility of BiMnO3 membranes is demonstrated by undergoing an ≈180° folding during an in situ bending test, which is consistent with the results of first‐principles calculations. The piezoelectric signal under a bending radius of ≈500 µm confirms the stable existence of electric polarization in freestanding BiMnO3 membranes. Moreover, the stable ferromagnetism of freestanding BiMnO3 membranes is demonstrated after 100 times bending cycles with a bending radius of ≈2 mm. 5.1% uniaxial tensile strain is achieved in freestanding BiMnO3 membranes, and the piezoresponse force microscopy (PFM) phase retention behaviors confirm that the ferroelectricity of membranes can survive stably up to the strain of 1.7%. These super‐flexible membranes with stable ferroelectricity and ferromagnetism pave ways to the realizations of multifunctional flexible electronics. [ABSTRACT FROM AUTHOR]

BaFe12O19 (BaM) powders and their corresponding ceramics were prepared by the sol–gel method at different solution concentrations (0.195–0.325 mol/L). The effects of solution concentration on microstructure, surface morphology, electrical properties, and magnetic properties of BaM powder BaM ceramics were systematically studied. XRD results show that the powders are pure BaM phase. SEM results show that with the increase in solution concentration, the grain size of ceramic increases, and the grain size of hexagonal sheet structure decreases gradually. At room temperature, when the solution concentration is 0.195 mol/L, ceramics' saturation polarization intensity and residual polarization intensity reach the maximum, which are 0.528 μC/cm2 and 0.297 μC/cm2, respectively. When the solution concentration is 0.325 mol/L, the ferroelectric properties of ceramic deteriorate due to the influence of leakage current. The ferroelectric hysteresis loop and magnetic hysteresis loop of ceramics show the multiferroic properties of ceramics at room temperature, which provides a new choice for single-phase multiferroic materials and lays a foundation for the multi-functionalization of BaM devices. [ABSTRACT FROM AUTHOR]

Ni-Mn-X (X = group IIIA-VA elements) Heusler alloys have been seen to exhibit multiferroic effects such as magnetic/metamagnetic shape memory (MSM/MMSM), magnetocaloric (MC), direct energy conversion etc. and have a large potential for diverse applications in actuation, magnetic refrigeration and conversion of low grade waste heat into electricity. Beneath the multifunctional potential of these alloys is a magnetostructural coupling encompassing structural and magnetic transformations, which in turn depends on alloy compositions. As compositions are varied different crystal structures are evolved and it becomes essential that the structures are accurately characterized for their microstructures. This paper provides a short review of characterization techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) with examples from our work as well as literature. Emphasis is laid on XRD, TEM and DSC, which are very important for microstructural characterization. [ABSTRACT FROM AUTHOR]

A low cost and simple auto combustion method was used to prepare the Bi1-xSrxFeO3 (x=0.0, 0.04, 0.08, 0.12, 0.16) multiferroics samples. X-ray diffraction patterns confirms the integration of BFO pure phase nanoparticles with a perovskite structure of ABO3 type having space group R3c. Spherical structure with little agglomeration was observed during the morphological studies of the prepared samples. Sr2+ substituted at the A-site produces expansion in Raman modes and increased variations in cation site occupancy. Impedance analyzer was used to examine the frequency dependent dielectric parameters (ε', tanδ), electric conductivity (σac), impedance (Z) and electric modulus (M' and M") of the samples in frequency between 20 Hz and 20 MHz). Maximum value of dielectric constant was observed at very low frequency for x=0.0 samples and it decreases by increasing concentration. Resonance peak was observed in tangent loss for high content of strontium. Maximum value of Impedance was observed at low frequency and it decreases by increasing frequency which is due to the grain and grain boundary contributions. It is observed that ac conductivity of the samples is found to be frequency dependent and it varies with doping of Sr in BFO. Improved polarization was examined in P-E loop of Sr doped BFO nanoparticles. [ABSTRACT FROM AUTHOR]

The Bi5Ti3(Fe1−xCox)O15 (x = 0, 0.4, 0.5, 0.6, 0.7) ceramics synthesized by solid state reaction are investigated. The microstructures are Aurivillius phase with perovskite layered structure, which were analyzed by X-ray diffraction and Raman spectroscopy test. The temperature-dependent magnetization was systematically investigated for all samples with different Co doping ratios. The magnetization reversal effects were found in both ZFC and FC curves with one or two compensation temperature. And the compensate temperatures change with different x. The temperature-induced magnetization reversal may attribute to the competition between the super-exchange interaction of Fe3+-O-Fe3+ and Co3+-O-Co3+, the DM interaction of Fe3+-O-Co3+ chains, and the magneto-crystalline anisotropy. This competition can be affected by the contents of Fe ions to Co ions. The study of multiferroic material Bi5Ti3(Fe1−xCox)O15 ceramics with magnetization reversal effects has important significance in the Information Security Engineering, for the switch effect with different magnetizations and temperatures. [ABSTRACT FROM AUTHOR]

2D van der Waals (vdW) multiferroic heterostructures have potential applications in novel 2D spintronic devices. Here, the electronic structure and magnetic anisotropy of 2D vdW multiferroic Mn2CFCl/CuBiP2Se6 heterostructures are investigated systematically by first‐principles calculations. Ferroelectric material CuBiP2Se6 has a built‐in electric field. Mn2CFCl is a half‐metallicity with ferromagnetic. The plane average potential difference of Mn2CFCl/CuBiP2Se6 heterostructures is 0.02 eV in P↓ state and 0.39 eV in P↑ state. The magnetic anisotropy of P↑ and P↓ states is shown perpendicular magnetic anisotropy (PMA). The P↑ state exhibits metallic character with the biaxial strain of 4%, −6%, while the P↓ state demonstrates half‐metallicity at a strain of 2%, 4%, 6%. The P↑ state shows PMA at the different biaxial strain. However, the P↓ state shows PMA at biaxial strain of −2%, −4%, and 6%, which shifts PMA to in‐plane magnetic anisotropy at −6%, 2%, and 4%. These tunable electronic structure and magnetic anisotropy suggest that the 2D multiferroic Mn2CFCl/CuBiP2Se6 vdW heterostructures have potential applications in spintronic devices. [ABSTRACT FROM AUTHOR]

The use of additives as a sintering aid for promoting densification is well-known in processing structural ceramics. In leaky ferroelectric ceramics (e.g., BiFeO 3 -based systems), additives are also used to reduce the leakage current, improve the poling efficiency and the piezoelectric response of a material. A less investigated aspect is how additives affect the multiferroic (ferroelectric and magnetic) features of BiFeO 3 -based ceramics. In this work, we report a systematic study of the effect of different additives viz, MnO 2 , CuO, K 2 CO 3 and KMnO 4 on the microstructural, electromechanical, and magnetic properties of Dy-modified BiFeO 3 –PbTiO 3. We found that all the additives help in the precipitation of the ferrimagnetic dysprosium iron garnet phase. The additives containing potassium (K) tend to suppress the grain size. We found that the best combination of ferroelectric and ferromagnetic behaviour was found in a mixture of additives. [ABSTRACT FROM AUTHOR]

The realization of antiferromagnetic multiferroics is of great significance both for fundamental perspective and for potential use in nanoscale devices. Although almost all the known multiferroics in three-dimensional systems are antiferromagnetic, antiferromagnetic multiferroics is rarely explored in 2D lattice. Here, using first-principles calculations, we report the identification of 2D antiferromagnetic ferroelastic multiferroics in single-layer transition-metal oxyhalides VOX (X = Cl, Br). Both systems are robust antiferromagnetic semiconductors with a wide bandgap and exhibit an in-plane magnetization orientation. Also they possess extraordinary ferroelasticity with high ferroelastic transition signal and moderate switching barrier. Moreover, the antiferromagnetic and ferroelastic orders in them can be coupled together, leading to the exotic ferroelastic control of in-plane magnetic anisotropy. These phenomena and insights are useful for the fundamental research in antiferromagnetic multiferroics and would enable a wide range of applications in nanodevices. [ABSTRACT FROM AUTHOR]