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Multiferroic BaTiO 3 exhibiting ferroelectric and ferromagnetic behavior was synthesized via the high-energy ball milling of pure BaTiO 3 (BTO) powders for durations ranging from 15 to 60 min, followed by pressing and sintering at 1200 °C X-ray diffraction patterns of all synthesized samples predominantly revealed a BTO phase with a tetragonal structure and a secondary Ba 12 Fe 28 Ti 15 O 84 (BFTO) phase. The BFTO phase was formed after milling for more than 30 min because of chemical interactions between the BTO powder and milling media. Vibrating sample magnetometry confirmed the ferromagnetic nature of the sintered pellets. The specific magnetization increased with increasing milling duration, reaching a maximum value of 1.15 emu/g after 60 min of milling. This increase can be attributed to the distortion of the crystal structure and presence of a secondary phase, as confirmed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Additionally, electrical characterization revealed the dielectric nature of the materials, with relative permittivity ranging from 500 to 1800, maximum spontaneous polarization from 9.77 to 11.31 μC/cm2, coercive field from 3.86 to 11.12 kV/cm, and AC conductivity from 1 × 10−6 to 1 × 10−3 S/cm. The method described in this study is a simple and cost-effective approach to produce multiferroic materials with ferroelectric and relaxor ferroelectric behavior at room temperature, broadening their potential for technological applications. [ABSTRACT FROM AUTHOR]

The unique ability of multiferroic materials to display the effect of magnetoelectric coupling, ideally at room temperature, makes them an enormous source of technological application. La-doped Bi 0.9 FeO 3 is a well-known potential applicant to be operated in multiferroic applications but, weak magnetoelectric response is one of this material's limitations. To address this issue, a series of nanocomposites is presented here by combining them with optimized SrFe 12 O 19 contents. The SrFe 12 O 19 has a hexagonal crystal structure with space group P 6 3 / mmc while Bi 0.9 La 0.1 FeO 3 (BLFO) possesses a rhombohedral crystal structure with space group R 3 m , confirmed by structural analysis. A homogenous distribution of grains in bi/phase composites was seen. Using PE loops, the ferroelectric nature of this composite is determined, revealing significant polarization, remanent polarization, and efficiency. Recoverable energy and energy loss density from the charging and discharging curves demonstrate that the composite has potential for energy storage devices. Furthermore, fast switching capability of the composites make it more prominent because it consumes less energy while switching of the polarization. In addition, the magnetic properties of the composite also enhanced which make it potential candidate for utilization into multifunctional devices. [Display omitted] • Facile synthesis of multiferroic composites using low cost, non-toxic and time saving synthesis route. • Optimization of composite recipe to achieve considerable recoverable energy density. • Efficient and fast switching charge density. [ABSTRACT FROM AUTHOR]

Topological spin Hall effect (TSHE), promoted by coupling between noncoplanar spins and real‐space topology, is a significant phenomenon in condensed matter physics. However, the control of TSHE characteristics is missing due to its intrinsic robustness, and such fundamental difficulty prevents it from being used for spintronics up to now. Here, a rational design approach is demonstrated to engineer TSHE in a controllable and reversible fashion. Through symmetry and model analysis, it is unveiled that antiferromagnetic topological charge, as well as Lorentz forces, acted on conduction electrons, can be coupled with Dzyaloshinskii‐Moriya interaction chirality for antiferromagnetic bimerons in 2D multiferroic materials. Such coupling guarantees the ferroelectric control of TSHE. Using first‐principles calculations and atomic spin model simulations, the validity of this mechanism is further demonstrated in multiferroic monolayer CuCr2Se4 with experimental feasibility. The alter‐chirality of the Dzyaloshinskii‐Moriya interaction is found to play a crucial role in realizing this mechanism. This results extend TSHE to be used in spintronics and open a new direction for spintronics research. [ABSTRACT FROM AUTHOR]

Multiferroic fluids are novel fluid-based multiferroic composites in which particles can change their magnetization/polarization direction with an external field. In this study, CoFe2O4–PbZr0.52Ti0.48O3 (CFO-PZT) multiferroic fluids were prepared by the milling method, and the effects of PZT particle size on settlement stability and magnetoelectric properties were systematically investigated. Crystal structure analysis shows that pure-phase CFO and PZT particles were successfully prepared. The microscopic morphology analysis indicates that the PZT particle size decreases as the carbon template size increases. Settlement stability is better when the particle size is 1.36 ± 0.04 μm. As the particle size decreases, the dielectric constant first increases then decreases, and finally increases. The residual polarization intensity decreases with decreasing particle size, but the saturation polarization intensity first increases and then decreases. After the magnetic field is applied, dielectric characteristics and ferroelectric properties decrease, showing the "negative magnetoelectric effect". When the particle size is 1.89 ± 0.04 μm, the CFO-PZT multiferroic fluid has the maximum magnetodielectric and magnetoelectric coupling coefficients of 3.36% and − 3.39 V/(cm·Oe), respectively. Therefore, multiferroic fluids are expected to broaden the application fields of multiferroic materials. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) multiferroic materials are recognized as promising candidates for next-generation nanodevices due to their tunable magnetoelectric coupling and distinctive physical phenomena. In this study, we proposed a novel 2D multiferroic van der Waals heterostructure (vdWH) by stacking atomic layers of ferroelectric In2Se3 and ferromagnetic MnI3. Using first-principles calculations, we found that the MnI3/In2Se3 vdWH exhibit robust metallic conductivity across various spin and polarization states, preserving the distinctive band characteristics of isolated In2Se3 and MnI3. However, the alignment of Fermi levels causes the conduction band minimum (CBM) and valence band maximum (VBM) of In2Se3 and MnI3 to shift relative to their original band structures. Remarkably, the MnI3/In2Se3 with the upward polarization state of In2Se3 exhibits an Ohmic contact. Switching the polarization direction of In2Se3 from upward to downward can transform the MnI3/In2Se3 vdWH from an Ohmic contact to a p-type Schottky contact, while also modifying its dipole moment, magnetic strength and direction. Based on these properties of MnI3/In2Se3 vdWH, we designed the field-effect transistors (FETs) with high on/off rates and nonvolatile data storage device. Furthermore, the Schottky barrier heights (SBHs), magnetic moment, and dipole moment of MnI3/In2Se3 vdWH can also be effectively regulated by reducing the interlayer distance. With the continuous reduction of the interlayer distance of MnI3/In2Se3 vdWH, its easy magnetization axis is expected to shift from in-plane to out-of-plane. These findings offer new insights for the design and development of the next-generation spintronic and nonvolatile memory nanodevices. [ABSTRACT FROM AUTHOR]

Multiferroic materials have been intensively pursued to achieve the mutual control of electric and magnetic properties. The breakthrough progress in 2D magnets and ferroelectrics encourages the exploration of low-dimensional multiferroics, which holds the promise of understanding inscrutable magnetoelectric coupling and inventing advanced spintronic devices. However, confirming ferroelectricity with optical techniques is challenging in 2D materials, particularly in conjunction with antiferromagnetic orders in single- and few-layer multiferroics. Here, we report the discovery of 2D vdW multiferroic with out-of-plane ferroelectric polarization in trilayer NiI2 device, as revealed by scanning reflective magnetic circular dichroism microscopy and ferroelectric hysteresis loops. The evolution between ferroelectric and antiferroelectric phases has been unambiguously observed. Moreover, the magnetoelectric interaction is directly probed by magnetic control of the multiferroic domain switching. This work opens up opportunities for exploring multiferroic orders and multiferroic physics at the limit of single or few atomic layers, and for creating advanced magnetoelectronic devices. The authors find the coexistence of ferroelectric and antiferroelectric states induced by chiral degeneracy in helical magnetic order in trilayer NiI2, along with the emergence of exotic magnetoelectric coupling. [ABSTRACT FROM AUTHOR]

Improving the hardness and wear resistance of die cutting tools is an important issue in the study of the service life of die cutting equipment. Using laser cladding technology, nickel-based composite coatings with varying BiFeO3 contents were prepared on a 45 steel substrate, because BiFeO3 can have an effect on the dilution rate and microstructure of the sample; morover BiFeO3 is a new type of multiferroic material with certain magneto-electric coupling effects which can be prepared for the study of added magnetic fields. The microstructure and morphology were characterized to determine the optimal BiFeO3 content. Based on the optimal addition of BiFeO3, a comparative analysis was conducted to investigate the effect of different magnetic field strengths under a composite energy field on the microstructure, hardness, and wear resistance of Ni-based WC cladding layers. The results show that the optimal addition of BiFeO3 was 5 wt%. At this concentration, there were no significant porosity defects in the coating, and the dilution rate was appropriate (4.77%). Additionally, the interface bonding strength was also increased. With optimal BiFeO3 addition, stirring with different magnetic field strengths was applied to the cladding layer, and the results show that the aspect ratio of the cladding layer gradually increased with increasing the alternating magnetic field strength. When the magnetic field strength in the composite energy field was 40 mT, the microstructure was fine and uniform, the hardness of the cladding layer reached the highest level, about 925.2 HV1.0, the wear resistance was also the best, the friction coefficient of the cladding layer was about 0.54, and the width of the wear mark was about 0.53 mm. [ABSTRACT FROM AUTHOR]

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na 0.5 Bi 0.5 TiO 3) and Co–Ti substituted Barium Hexaferrite (BaFe 12-2x Co x Ti x O 19 ; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63 / mmc hexagonal phases corresponding to Na 0.5 Bi 0.5 TiO 3 and BaFe 12-2x Co x Ti x O 19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x ≠ 0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future. [ABSTRACT FROM AUTHOR]

Using a microscopic model and Green's function theory, we have investigated the co-doping effect on ferroelectric KNbO3 nanoparticles. Let us emphasize that while the doping with transition metal ions at the Nb site leads an increase in the ferromagnetism and a reduction the band gap, it also decreases the ferroelectricity. On the other hand, doping with La or Ba at the K site leads to enhanced polarization, but does not lead to the appearance of ferromagnetism and reduction in the band gap. Therefore, we have studied co-doping with La/Cr and La/Co ions, which leads to increasing the magnetization and polarization as well as to strongly decreasing the band gap energy. Thus, we observe a multiferroic material with room-temperature ferromagnetism and ferroelectricity as well as small band gap energy which can be tuned using various co-doping ions. There is a good agreement with the existing experimental data. [ABSTRACT FROM AUTHOR]

The ever-growing need for advancement in data storage technology demands materials that can be controlled by as many degrees as possible. In this regard, multiferroic materials that show response both in electric and magnetic dimensions are of great interest especially when being investigated in two-dimensional materials that have their potential applications. In this study, we have incorporated Lanthanum (La) doped Bismuth Ferrite (BLFO), and La and Selenium (Se) co-doped BFO (BLFSO) with two-dimensional layered titanium carbide (Ti 3 C 2 T x) from the class of MXene as hybrid composites. The structural, optical and morphological investigation validated the successful etching of MXene from MAX, successful hybrid formation with conserved crystal structure and new phases of titanium dioxide (TiO 2) detected when the samples underwent heat treatment. This heat treatment was performed in order to enhance the multiferroic properties owing to the presence of TiO 2. Our results showed that the heated BLFSO-embedded Ti 3 C 2 T x hybrid composite showed maximum remnant polarization and higher dielectric response when measured with respect to the varying electric field and at different frequencies. The prepared samples also exhibited tunable polarization response at an applied static magnetic field, unveiling their magnetoelectric properties. [ABSTRACT FROM AUTHOR]

This study aims to enhance the multiferroic properties of bismuth ferrite (BFO) by investigating the effects of substitution with erbium (Er) on the material's structural, optical, and magnetic characteristics. Er-substituted bismuth ferrite (Bi1−xErxFeO3) (x = 0, 0.04, 0.08, 0.12, 0.16) nanoparticles (NPs) were synthesized via the very cost-effective Pechini modified sol–gel method followed by auto-combustion. X-ray diffraction (XRD) patterns confirmed the crystallinity, structure, and purity of the phase, revealing the formation of single-phase materials. The bond structure of the prepared samples was examined using Fourier transform infrared (FTIR) spectroscopy, confirming the significant stretching and bending of bonds of perovskites. Electron paramagnetic resonance (EPR) findings suggested a broadening of the signal as well as a shift of the center of resonance to lower fields. The experimental findings revealed that Er doping has a significant effect on the magnetic ordering and saturation magnetization of BiFeO3. In addition, UV–Vis spectroscopy demonstrated that the energy bandgap in the prepared samples varies from 2.13 eV to 1.71 eV. This research contributes to an understanding of the enhanced structural, magnetic, and optical properties of Er-substituted BFO nanoparticles, which is useful for designing and developing multiferroic materials with enhanced magnetic functionality for next-generation magnetoelectric devices, optoelectronic devices, and photocatalysts. [ABSTRACT FROM AUTHOR]

A hydroelectric cell has been coined as an accomplished device keeping the ability to produce current just by adsorbing a few microliters of water. These cells are the new source of generating green energy which involves no evolution of toxic gases like NO2, SO2, CO, etc. Our current research focuses on studying how to increase the maximum output current (I) in the pure cobalt ferrites by doping with rare-earth ion, yttrium. The yttrium-doped cobalt ferrites with composition (CoYxFe2−xO4, x = 0.00, 0.10, and 0.20) have been prepared using a modified sol–gel citrate method. X-ray diffractogram (XRD) confirmed the formation of cubic crystal structures with crystallite size less than 30 nm. Energy dispersive x-ray (EDX) patterns confirmed the presence of elements (Y, Co, Fe, O) in the prepared compositions. The ionic diffusion mechanism confirmed the dissociation of water molecules by the cations present on the surface of the material at room temperature. Vibrating sample magnetometer (VSM) analysis revealed the increase in coercivity values from 948.81 Oe to 2580.09 Oe with the increase in the concentration of yttrium ions in the cobalt ferrite (CFO) lattice. The V–I polarization curves measured the maximum output current and voltage as around 8.6 mA and 1.1 V, respectively, for the 20% yttrium-doped CFO hydroelectric cells (area = 4 cm2). [ABSTRACT FROM AUTHOR]

Two-dimensional materials possessing intrinsic multiferroic properties have long been sought to harness the magnetoelectric coupling in nanoelectronic devices. Here, we report the achievement of robust type I multiferroic order in single-layer chromium trihalides by decorating transition metal atoms. The out-of-plane ferroelectric polarization exhibits strong atomic selectivity, where 12 of 84 single-layer transition metal-based multiferroic materials possess out-of-plane ferroelectric or antiferroelectric polarization. Group theory reveals that this phenomenon is strongly dependent on p–d coupling and crystal field splitting. Cu decoration enhances the intrinsic ferromagnetism of trihalides and increases the ferromagnetic transition temperature. Moreover, both ferroelectric and antiferroelectric phases are obtained, providing opportunities for electrical control of magnetism and energy storage and conversion applications. Furthermore, the transport properties of Cu(CrBr3)2 devices are calculated based on the non-equilibrium Green's function, and the results demonstrate outstanding spin-filtering properties and a low-bias negative differential resistance (NDR) effect for low power consumption. [ABSTRACT FROM AUTHOR]

Increasing demand for functional materials crucial for advancing new technologies has motivated significant scientific and industrial research efforts. High-entropy materials (HEMs), with tunable properties, are gaining attention for their use in high-frequency transformers, microwave devices, multiferroics, and high-density magnetic memory components. The initial exploration of HEMs started with high-entropy alloys (HASs), such as CrMnFeCoNi, CuCoNiCrAlxFe, and AlCoCrTiZn and paved the way for a multitude of HEM variations, including oxides, oxyfluorides, borides, carbides, nitrides, sulfides, and phosphides. In this study, we fabricated the high-entropy oxide (HEO) compound B i 0.5 L a 0.1 I n 0.1 Y 0.1 N d 0.1 G d 0.1 F e O 3 through the solid-state synthesis method. Magnetic measurements at 300 K show ferromagnetic behavior with significant coercivity. At the same time, this novel composition exhibits excellent dielectric properties and shows potential for electronic applications demonstrating that a high-entropy approach can expand the compositional range of rare earth multiferroics and improve the multifunctional properties in multiferroic applications. [ABSTRACT FROM AUTHOR]

Multiferroic materials are an exceptional class of magnetic materials where long-range magnetic and ferroelectric orders coexist, thus provoking the researchers' interest from both basic and practical points of view. The magnetoelectric multiferroics are materials that combine coupled electric and magnetic dipoles. Recently, research has focused on the occurrence of the magnetoelectric effect in some hexagonal ferrite types and the possibility of their use as single-phase multiferroic and magnetoelectric materials. For many years, various hexaferrites have been intensively studied as materials for permanent magnets, high-density recording media, microwave devices, biomedical applications, etc. The magnetic structure and especially the specific magnetic spin arrangement under certain conditions proved to be key factors for the realization of magneto-electric phases in hexaferrites. Here some recent advances in our studies of the magnetic phase transitions in the Y-type hexaferrites are overviewed. In particular, the influence of the replacement of non-magnetic Me2+ cations with magnetic cations and of magnetic Fe3+ cations with non-magnetic ones on the magnetic properties and occurring magnetic phase transitions in Y-type hexaferrites are exemplified with Ba0.5Sr1.5Zn2Fe12O22. [ABSTRACT FROM AUTHOR]

The search for new materials and compositions, in which the phenomena of ferrimagnetism and ferroelectricity are closely coupled, is of great technological interest. In the present study, composite systems of (BaTiO 3) (100- x)% /(CoNb 0 · 02 Fe 1 · 98 O 4) x % where x = 0, 2, 5, 10, 20, and 100% were produced. Initially, BaTiO 3 (BTO) was made by sol-gel combustion approach and CoFe 1 · 98 Nb 0 · 02 O 4 (CoFeNbO) was made by hydrothermal method. Both compounds were then combined via solid-state reaction route to form the composite systems. According to X-ray diffraction, the pristine BTO and CoNbFeO display tetragonal and cubic structures, respectively, and all composite systems consisted of the cubic phase for BTO and spinel phase for CoNbFeO. Scanning electron microscopy showed a decrease in grain size (from 0.552 μm to 0.194 μm) and porosity (from 18.65% to 4.57%) as the CoNbFeO content increases from x = 0 to x = 20%, respectively. The influence of magnetic CoNbFeO content on the magnetic, ferroelectric, magnetoelectric coefficient, electric, and dielectric properties of composite systems has been investigated. The ferromagnetic and ferroelectric natures of diverse composite systems are reflected via the registered M-H and P-E loops at ambient temperature. A steady increase in magnetic parameters such as saturation magnetization and remanent magnetization is observed as the spinel ferrite CoNbFeO content increases. Similarly, the values of the electric coercivity increased from 1.65 kV/cm for x = 0% to 3.99 kV/cm for x = 20%. The frequency-dependent dielectric and electrical measurements were also investigated at various temperatures. By raising the measurement temperature, the dielectric polarization was found to increase for composite systems with x > 2%. Interestingly, the tangent loss was reduced for different composite systems in comparison to pristine BTO and CoNbFeO materials. The lowest tangent loss values were noticed for x = 5% composite system. All composite systems revealed good magnetoelectric coupling with coupling coefficient magnitudes up to a maximum value of ∼22.5 mV/cm.Oe, indicating that they can be potential candidates for use in advanced multifunctional electric devices. [ABSTRACT FROM AUTHOR]

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This paper presents a novel approach for the fabrication of magnetoelectric composites aimed at enhancing cross-coupling between electrical and magnetic phases for potential applications in intelligent sensors and electronic components. Unlike previous methodologies known for their complexity and expense, our method offers a simple and cost-effective assembly process conducted at room temperature, preserving the original properties of the components and avoiding undesired phases. The composites, composed of PZT fibers, cobalt (CoFe2O4), and a polymeric resin, demonstrate the uniform distribution of PZT-5A fibers within the cobalt matrix, as demonstrated by scanning electron microscopy. Detailed morphological analyses reveal the interface characteristics crucial for determining overall performance. Dielectric measurements indicate stable behaviors, particularly when PZT-5A fibers are properly poled, showcasing potential applications in sensors or medical devices. Furthermore, H-dependence studies illustrate strong magnetoelectric interactions, suggesting promising avenues for enhancing coupling efficiency. Overall, this study lays the basic work for future optimization of composite composition and exploration of its long-term stability, offering valuable insights into the potential applications of magnetoelectric composites in various technological domains. [ABSTRACT FROM AUTHOR]

The multiferroic magnetoelectric 2–2 laminated composite systems with BaTiO3 and NiFe2O4 as the ferroelectric and ferrimagnetic phases were successfully fabricated by co-firing technique. For this phase, pure BaTiO3 and NiFe2O4 were successfully synthesized by sol–gel and polyol method, respectively. The structural, microstructural, multiferroic and magnetoelectric coupling properties of phase pure and co-fired systems were investigated using X-ray diffraction, HR-TEM, SEM–EDX, P–E Loop, VSM and magnetoelectric coupling analysis. The multiferroic and magnetoelectric coupling properties of the laminated systems were compared with the mixed system having similar weight percentage of BaTiO3 and NiFe2O4. The fabricated composite systems show good multiferroic and magnetoelectric properties. Compared to mixed composite systems, the laminated structure has an enhanced magnetoelectric (ME) coupling of 6.42 mV/cm.Oe. This variation in ME coupling is attributed to the low leakage current effects in the laminated systems. The ME coupling in the laminates varies with the nature and number of layers. For laminated composite systems, the ME coupling coefficient is found to increase from 6.42 mV/cm.Oe to 10.48 mV/cm.Oe with increase in the number of layers. [ABSTRACT FROM AUTHOR]

The discovery of novel two-dimensional (2D) multiferroic materials is attractive due to their potential for the realization of information storage and logic devices. Although many approaches have been explored to simultaneously introduce ferromagnetic (FM) and ferroelectric (FE) orders into a 2D material, the resulting systems are often plagued by weak magnetoelectric (ME) coupling or limited room-temperature stability. Here, we present a superlattice strategy to construct non-centrosymmetric AM2X4 multiferroic monolayers, i.e., intercalating transition metal ions (A) into the tetragonal-like vacancies of transition metal dichalcogenide bilayers (MX2). Starting from 960 intercalated AM2X4 compounds, our high-throughput calculations have identified 21 multiferroics with robust magnetic order, large FE polarization, low transition barrier, high FE/FM transition temperature, and strong ME coupling. According to the origin of magnetism, we have classified them into twelve type-a, seven type-b, and two type-c multiferroics, which exhibit different ME coupling behavior. During the switching of polarization, the reversal of skyrmions chirality, the transition of the magnetic ground state from FM to antiferromagnetic, and the changes in spin-polarized electron distribution were observed in type-a, type-b, and type-c 2D multiferroic materials, respectively. These results substantially expand the family of 2D ferroic materials and pave an avenue for designing and implementing nonvolatile logic and memory devices. [ABSTRACT FROM AUTHOR]

Direct conversion from terahertz photon to charge current is a key phenomenon for terahertz photonics. Quantum geometrical description of optical processes in crystalline solids predicts existence of field-unbiased dc photocurrent arising from terahertz-light generation of magnetic excitations in multiferroics, potentially leading to fast and energy-efficient terahertz devices. Here, we demonstrate the dc charge current generation from terahertz magnetic excitations in multiferroic perovskite manganites with spin-driven ferroelectricity, while keeping an insulating state with no free carrier. It is also revealed that electromagnon, which ranges sub-terahertz to 2 THz, as well as antiferromagnetic resonance shows the giant conversion efficiency. Polar asymmetry induced by the cycloidal spin order gives rise to this terahertz-photon-induced dc photocurrent, and no external magnetic and electric bias field are required for this conversion process. The observed phenomena are beyond the conventional photovoltaics in semi-classical regime and demonstrate the essential role of quantum geometrical aspect in low-energy optical processes. Our finding establishes a paradigm of terahertz photovoltaic phenomena, paving a way for terahertz photonic devices and energy harvesting. Authors discover that the spin excitations of multiferroics convert the terahertz photon to the unidirectional charge current through the quantum geometrical aspect of optical process, paving the way to the terahertz photonics. [ABSTRACT FROM AUTHOR]

In this work, h -RFeO 3 multiferroic high-entropy ceramics are designed by introducing high-entropy concept with four elements (Yb, Lu, In, Sc) for R site. (Yb 0.25 Lu 0.25 In 0.25 Sc 0.25)FeO 3 high-entropy ceramics are prepared by the standard solid-state reaction methods. The samples prepared with precursors were identified to crystalize in the pure hexagonal structure with polar space group (P 6 3 cm) at room temperature. By the analysis of the variable XRD patterns, it is speculated that the ferroelectric transition temperature of the sample is above 773 K. Meanwhile, three magnetic anomalies are determined for high-entropy ceramics, which is the antiferromagnetic transition at Néel temperature T Ñ 280 K, the spin-reorientation temperature T SR ∼145 K and the reasonable ferromagnetic-like clusters without long ordering in T N < T < T A (∼397 K). Besides, it is observed that the peak intensity of the pyroelectric current around T N can be tuned by magnetic field, which is indicated the magnetoelectric coupling effect in (Yb 0.25 Lu 0.25 In 0.25 Sc 0.25)FeO 3 high-entropy ceramics. These results indicate the ferroelectric and antiferromagnetic orders are coexist in the h- RFeO 3 high-entropy ceramics as promising near room temperature multiferroic materials, and it is an effective way to obtain a new type single-phase multiferroic materials. [ABSTRACT FROM AUTHOR]

Multiferroic materials, which simultaneously exhibit ferroelectricity and magnetism, have attracted substantial attention due to their fascinating physical properties and potential technological applications. With the trends towards device miniaturization, there is an increasing demand for the persistence of multiferroicity in single-layer materials at elevated temperatures. Here, we report high-temperature multiferroicity in single-layer CuCrSe2, which hosts room-temperature ferroelectricity and 120 K ferromagnetism. Notably, the ferromagnetic coupling in single-layer CuCrSe2 is enhanced by the ferroelectricity-induced orbital shift of Cr atoms, which is distinct from both types I and II multiferroicity. These findings are supported by a combination of second-harmonic generation, piezo-response force microscopy, scanning transmission electron microscopy, magnetic, and Hall measurements. Our research provides not only an exemplary platform for delving into intrinsic magnetoelectric interactions at the single-layer limit but also sheds light on potential development of electronic and spintronic devices utilizing two-dimensional multiferroics. The authors observe multiferroicity in a single-layer non van der Waals material, CuCrSe2. The coexistence of room-temperature ferroelectricity and ferromagnetism up to 120 K is corroborated by a set of comprehensive experimental techniques. [ABSTRACT FROM AUTHOR]

The exploration of multiferroic materials and their interaction with light at the nanoscale presents a captivating frontier in materials science. Bismuth Ferrite (BiFeO3, BFO), a standout among these materials, exhibits room-temperature ferroelectric and antiferromagnetic behaviour and magnetoelectric coupling. Of particular interest is the phenomenon of photostriction, the light-induced deformation of crystal structures, which enhances the prospect for device functionality based on these materials. Understanding and harnessing multiferroic phenomena holds significant promise in various technological applications, from optoelectronics to energy storage. The orientation of the ferroelectric axis is an important design parameter for devices formed from multiferroic materials. Determining its orientation in the laboratory frame of reference usually requires knowing multiple wavevector transfer (Q-Vector) directions, which can be challenging to establish due to the need for extensive reciprocal-space searches. Our study demonstrates a method to identify the ferroelectric axis orientation using Bragg Coherent X-ray Diffraction Imaging (BCDI) measurements at a single Q-vector direction. This method involves applying photostriction-inducing laser illumination across various laser polarisations. Our findings reveal that photostriction primarily occurs as a surface phenomenon at the nanoscale. Moreover, a photo-induced crystal length change ranging from 30 to 60 nm was observed, consistent with earlier findings on bulk material. [ABSTRACT FROM AUTHOR]

BiFeO3‐BaTiO3‐based ceramics are promising multiferroic materials for a wide range of applications. In this paper, the effects of different ionic valence state((Ga0.5Ta0.5)4+, Ta5+) doping on the structure and properties of 0.73BiFeO3‐0.27BaTi1‐y(Ga1‐xTax)yO3 ceramics were investigated. X‐ray diffraction analysis showed that all samples were determined by rhombohedral R3c phase and tetragonal P4mm phase. A frequency‐independent dielectric anomaly with obvious thermal hysteresis was detected in all samples, indicating the first‐order ferroelectric phase transition, and the Curie temperatures were all above 600°C. The ferroelectric analysis found that the doping of donor element Ta reduced the coercive field, with a slight decrease of remanent polarization, which can be attributed to the soft effect of Ta element. Meanwhile, the magnetic properties were enhanced for all samples, with a maximum in 15T (x = 1, y =.015) sample, where Mr =.13 emu/g. According to relevant analysis, high‐valence element substitution can enhance the magnetic properties and reduce the coercive field of BiFeO3, while low‐valence element substitution can reduce dielectric loss. This result points out a way for us to choose appropriate doping elements to improve the performance of BiFeO3 ceramics. [ABSTRACT FROM AUTHOR]

BiFeO3 is a rare single‐phase multiferroic which shows coupled ferroelectricity, ferroelasticity and antiferromagnetism at room temperature. Many fantastic properties of BiFeO3 are regulated by its domain structure. While (001) rhombohedral BiFeO3 thin films can possibly develop up‐to eight degenerate states of two‐variant 71° ferroelastic domain stripes, complete selective control of all possible switching paths between these states has not yet been achieved. Here, combining phase field simulations and scanning probe microscopy experiments, we demonstrated such a complete selective control. The tip bias and the built‐in field were shown to affect the volume fraction of the 71°, 109° and 180° switched domains in rhombohedral BiFeO3 thin films under single‐point loading. Meanwhile, tip scanning further broke the symmetry of the nucleated domains, leading to different switched domain patterns. We then grew BiFeO3 thin films with a specific two‐variant 71° ferroelastic domain state and showed that such a state could be deterministically switched into the other seven two‐variant domain states by collaborative controlling tip scanning and tip bias in scanning probe microscopy experiments. These results should deepen our current understanding on the domain switching kinetics in BiFeO3 thin films and indicate they are promising platforms for developing configurable electronic and spintronic devices. [ABSTRACT FROM AUTHOR]

Searching for multiferroic materials with ferromagnetic (FM) and ferroelectric (FE) properties holds promise for ultra‐high‐density and low‐energy‐consumption memory device applications, but 2D materials with both properties are rare. Herein, a general strategy to achieve nonvolatile electric field control of magnetism in the bilayer (BL) α‐In2Se3 by hole doping is proposed. By first‐principles calculations, it is demonstrated that hole doping can induce robust ferromagnetism in the bilayer α‐In2Se3 due to its unique flat Mexican‐hat‐shape valence band structure. Such band edges cause van Hove singularities (VHS), and proper hole doping can lead to time‐reversal symmetry breaking. The bilayer α‐In2Se3 exhibits ferromagnetism and ferroelectricity within a wide range of doping concentrations, resulting in an unexpected multiferroic phase. Furthermore, when the electrical polarization of α‐In2Se3 flips from downward to upward, it becomes non‐magnetic (NM) from ferromagnetic states in the As‐substituted bilayer α‐In2Se3, which can work as a nonvolatile magnetic storage unit. Remarkably, the As‐substituted bilayer α‐In2Se3 exhibits an enhanced magnetic moment of 1.2 μB per AsSe due to substantial charge transfer across the interface. Notably, the mechanism of electrically controlled magnetism is elucidated as the coupling among the Mexican‐hat‐like dispersion, ferromagnetism, and ferroelectricity. The findings offer a promising strategy for electrical writing and the magnetic reading memory device. [ABSTRACT FROM AUTHOR]

Bi0.8Ba0.1Er0.1Fe0.96Cr0.02Mn0.02O3 (BBEFCMO) multiferroic ceramic was synthesized through the sol-gel route. The impact of incorporating various dopants into both A and B sites of the BiFeO3 was investigated, and structural, Raman, dielectric, electric, and magnetic properties were studied. X-ray diffraction analysis and Raman spectroscopy revealed a rhombohedral structure with the R3c space group for the doped material (BBEFCMO). Dielectric properties were examined across a frequency range of 102–106 Hz. The present multiferroic material exhibits a colossal dielectric constant and minimal dielectric loss tangent, making it suitable for applications in energy storage. Furthermore, the Cole-Cole type of relaxation was deduced from the imaginary part of the modulus for both grain and boundary-grain contributions. Overall, this study indicates that substituting ions in both A and B sites of BiFeO3 significantly enhances its multiferroic properties, as evidenced by dielectric and magnetic measurements. [ABSTRACT FROM AUTHOR]

This study investigates the gas sensing capabilities of bulk Bi 2(1-x) La 2x Fe 4 O 9 with x = 0, and 0.05 systems (BFO 0, BLFO 5), using a fiber optic VOC sensor at room temperature. Structural and magnetic characterizations confirm the successful incorporation of La3+ into the Bi site of the BFO 0 lattice without altering the structure. BLFO 5 exhibits remarkable gas sensitivity towards benzene, with a normalized gas sensitivity of 47 counts/100 ppm. This enhanced sensitivity is attributed to the presence of oxygen vacancies, which contribute to BLFO 5's weak ferromagnetism. The rapid response (43 s) and recovery (51 s) times further demonstrate the promising potential of multiferroic materials for VOC detection. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to learn the morphological, structural, ferroelectric, dielectric, electromechanical, magnetoelectric, and magnetic properties, and DC conductivity of BaTiO3-Ni0.64Zn0.36Fe2O4 (BT-F) multiferroic composites compacted via the free sintering method. The influence of the ferrite content in ceramic composite materials on the functional properties is investigated and discussed. X-ray diffraction studies confirmed the presence of two main phases of the composite, with strong reflections originating from BaTiO3 and weak peaks originating from nickel-zinc ferrite. BT-F ceramic composites have been shown to exhibit multiferroism at room temperature. All studied compositions have high permittivity values and low dielectric loss, while the ferroelectric properties of the BT component are maintained at a high level. On the other hand, magnetic properties depend on the amount of the ferrite phase and are the strongest for the composition with 15 wt.% of F (magnetization at RT is 4.12 emu/g). The magnetoelectric coupling between BT and F phases confirmed by the lock-in technique is the largest for 15 wt.% ferrite. In the present work, the process conditions of the free sintering method for obtaining BT-F multiferroic composite with good electrical and magnetic properties (in one material) were optimized. An improved set of multifunctional properties allows the expansion of the possibilities of using multiferroic composites in microelectronics. [ABSTRACT FROM AUTHOR]

Controlling the direction of ferromagnetism and antiferromagnetism by an electric field in single-phase multiferroics will open the door to the next generation of devices for spintronics and electronics. The typical magnetoelectric coupling such as the linear magnetoelectric effect is very weak in type-I multiferroics and therefore the magnetoelectric switching is rarely achieved. Here, using first-principles simulations, we propose a magnetoelectric switching mechanism to achieve such highly desired control in orthorhombic multiferroics. One class of two-dimensional proper multiferroics (CrX2Se3 and MnX2Te3, X = Sn, Ge) and perovskite multiferroics (EuTiO3 and BiFeO3/LaFeO3 superlattice) are taken as examples to show the mechanism. In the ferroelectric switching process, the proper polarization rotates its direction by 180° and keeps its magnitude almost unchanged, the ferromagnetic or antiferromagnetic vector is rotationally switched by 180° following the rotation of ferroelectric polarization. This rotational magnetoelectric switching results from in-plane structural anisotropy and magnetic anisotropy, and the process of switching is governed by cosine functions from the phenomenological Landau-type models. This study addresses the challenge of magnetoelectric switching in type-I multiferroics by proposing a general magnetoelectric switching mechanism. [ABSTRACT FROM AUTHOR]

The magnetization mechanism of Co-doped BaTiO3 ultrathin films is a subject of debate, which results in difficulties with the design of new multiferroics based on BaTiO3 matrixes. With the aid of a first-principles approach, it was observed that when the interstitial site and Ti vacancy were filled with Co, the configuration behaved in a nonmagnetic manner, indicating the significance of the Co content. Moreover, in the case of Co substituting two neighboring Ti atoms, when a direct current field was applied in the [100] direction, the magnetic domains excluding those in the [100], [010], and [001] directions were directed away. Further, the magnetoelectric constant was evaluated at ~449.3 mV/cmOe, showing strong magnetoelectric coupling at room temperature. Clearly, our study indicates that strict control of Ba, Ti, O, and Co stoichiometry can induce an electric and magnetic field conversion in two-dimensional BaTiO3 and may provide a new candidate for single-phase multiferroics for application in next-generation multifunctional devices. [ABSTRACT FROM AUTHOR]

Multiferroic materials, where ferroelectric and magnetic orders coexist, have ignited substantial research interest due to the achievable manipulation of magnetic orders using external electric fields, a feature that has garnered serious interest for memory storage applications. Nonetheless, naturally occurring single-phase multiferroic materials are scarce, thus constraining options for practical use. Over the last decade, bismuth-based layered supercell (LSC) oxides have emerged as novel candidates for multiferroics, catalyzing extensive investigations in this domain. Additionally, these LSC systems are known for their anisotropic structures and optical properties, making them promising for application in optics such as polarizers, beam splitters, and modulators. This thorough review explores the development and current advancements in multiferroic bismuth-based LSC materials. It covers the diverse nature of LSCs, detailing their microstructure, properties, and the mechanics of self-assembly formation. It also highlights the remarkable multifunctional characteristics of LSC-based nanocomposites, with a particular focus on their applications in electronics and optics. Moreover, this review examines the significant potential of LSCs in practical applications, particularly through their integration onto silicon and flexible substrates via heteroepitaxy and film transfer techniques. Finally, it offers insights into potential future research avenues and the broader implications of these versatile LSC materials. [ABSTRACT FROM AUTHOR]

Due to the strong magneto-elastic coupling in ferromagnetic/ferroelectric heterostructures and the potential applications in low-power magnetoelectric nanodevices, ferroelastic domains and the corresponding dynamic evolution under external stimuli have attracted intense research interest. Using pulsed laser deposition method, we have successfully grown layered-perovskite Bi2WO6 thin films on SrTiO3 (001) substrates. Interestingly, for the as-grown thin films with step-flow morphology, the relationship between ferroelastic domain number and size shows a normal distribution, which is similar to the Boltzman distribution for confined gas molecules at equilibrium. In addition, with post-annealing, the thin films with as-grown island-like morphology can be optimized for layered morphology, and the initial small ferroelastic domains can grow into large domains. This study provides an effective strategy for ferroelastic domain engineering, which can be applied for the design of multiferroic heterostructures and low-power nanodevices. [ABSTRACT FROM AUTHOR]

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators. [ABSTRACT FROM AUTHOR]

In our studies, we combined two powdered materials, i.e., ferroelectric triglycine sulfate (TGS) and ferrimagnetic magnetite Fe3O4, to obtain a magnetoelectric composite. The ferroelectric (E) part, i.e., TGS, was a hybrid organic–inorganic crystal, which we obtained as a pure single crystal from an aqueous solution using a static water evaporation method. The magnetic (M) part of the composite was commercially available magnetite. The samples used for the dielectric and magnetoelectric measurements were cold-pressed and made in the form of a circular tablet. The measuring electrodes were made of silver-based conductive paste and were attached to the sample. We measured the temperature dependencies of selected electrical parameters (e.g., dielectric permittivity, electrical capacity, and loss angle tangent). We used the dynamic lock-in method to check whether magnetoelectric coupling existed between the E and M phases. In this paper, we present the dielectric properties of pure monocrystalline TGS as a reference sample and compare the results for TGS powder, TGS + carbon powder, and TGS + Fe3O4 powder. The magnetoelectric coupling presumably appeared for the composite TGS + 10 wt. % Fe3O4, as evidenced by the shift in the phase transition temperature in the TGS. Moreover, the theoretical interpretation of the effect is proposed. [ABSTRACT FROM AUTHOR]

Dense ceramic samples of wolframite-type MnMoO 4 (w -MnMoO 4) have been prepared by Cool-SPS (Spark Plasma Sintering) for the first time with the goal of investigating the magnetic, dielectric, and magneto-electric properties of this thermally fragile polymorph of MnMoO 4. Earlier studies found that w -MnMoO 4 converts to the structurally different α-MnMoO 4 phase if heated in air at 873 K, thus hindering fabrication of w -MnMoO 4 ceramics by conventional high-temperature sintering. Unsintered powder samples, which were prepared via a hydrothermal method, and dense ceramics elaborated by Cool-SPS have the same magnetic properties. Magnetic susceptibilities display Curie-Weiss behaviour, χ = C/(T-θ), with effective moments for Mn2+ ion μ eff ≈ 5.9 μ B /Mn-atom and negative Weiss temperatures θ ≈ - 96 to - 98 K. Unlike the isostructural multiferroic compounds MnW 1-x Mo x O 4 (0 ≤ x < 0.3) which exhibits at least two successive magnetic transitions below 15 K, w -MnMoO 4 undergoes only one paramagnetic-to-antiferromagnetic transition at T N ≈ 32 K. The field-dependent magnetization at 2 K shows a spin-flop transition at μ 0 H SF ≈ 2 T. Capacitance and dielectric losses obtained for a ceramic between 2 and 300 K in zero field and in a field of 9 T reveal several weak anomalies. Dielectric anomalies are observed at the magnetic phase transition, suggesting a magnetoelectric coupling. Qualitatively different dielectric and magnetodielectric behaviours occur in α-MnMoO 4 ceramics at low temperature. [ABSTRACT FROM AUTHOR]

Composite multiferroic materials were prepared using the conventional ceramic double sintering process, with composition of Ґ BaTiO3/(1 − Ґ) Cu0.3Ni0.1Zn0.6Fe2O4, where Ґ represents the mass fraction of the ferroelectric phase ranging from 0.3 to 0.9. The behavior of the bulk composites under external dynamic magnetic and electric fields was studied as a function of the ferroelectric phase content. The objective of this work is to establish a relationship between the irreversibility process and magnetic and electrical losses in composite magnetoelectric materials. Experimental measurements were correlated with the entropy production of materials. The results allow us to infer that in the explored frequency range (from 1 MHz to 1.8 GHz), entropy production not only decreases as the ferroelectric phase content increases but is also related to the magnetic losses. [ABSTRACT FROM AUTHOR]

This paper reports a multifunctional magnetic‐photoelectric laminate device based on the integration of spintronic material (La0.7Sr0.3MnO3) and multiferroic (Ni‐doped BiFeO3), in which the repeatable modulation effect on the photoelectric properties were achieved by applying external magnetic fields. More obviously, photocurrent density (J) of the laminate was largely enhanced, the change rate of J up to 287.6% is obtained. This sensing function effect should be attributed to the low‐field magnetoresistance effect in perovskite manganite and the scattering of spin photoelectron in multiferroic material. The laminate perfectly combines the functions of sensor and controller, which can not only reflect the intensity of environmental magnetic field, but also modulate the photoelectric conversion performance. This work provides an alternative and facile way to realize multi‐degree‐of‐freedom control for photoelectric conversion performances and lastly miniaturize multifunction device. The photoelectron transport process in BiFe0.9Ni0.1O3/La0.7Sr0.3MnO3 laminate thin film under external magnetic field. Here we reported on a magnetic‐photocurrent effect, which provides an optional way to manipulate photoelectric conversion properties in multiferroic thin films. [ABSTRACT FROM AUTHOR]

Lead iron niobate (PbFe 0.5 Nb 0.5 O 3 – PFN) thin films were synthesized by a modified sol-gel route, which offers the advantage of a rapid, simple and non-toxic reaction method. Polycrystalline perovskite-structured PFN thin films without pyrochlore phases were obtained on Pt/Ti/SiO 2 /Si substrates after sintering by rapid thermal annealing at 650 °C. TEM and AFM images confirmed the excellent quality of the sintered film, while EDS spectroscopy revealed the presence of oxygen vacancies near the film/substrate interface. Electric measurements show good dielectric properties and ferroelectric behavior, characterized by typical C–V curves and well-defined P-E ferroelectric loops at 1 kHz, with remanent polarization values of ∼12 μC/cm2. The polarization, however, increases with decreasing frequency, indicating the presence of leakage currents. I–V measurements show a significant increase in DC-conduction at relatively low fields (around 100 kV/cm). The films display ferromagnetic behavior at room temperature, with magnetic remanence around 30 emu/cm3 and a coercive field of 1 kOe. These values are significantly higher than those obtained for PFN powders fabricated by the same sol-gel route, as well as the magnetization values reported in the literature for epitaxial films. [ABSTRACT FROM AUTHOR]

• The indentation behaviors of multiferroic composite materials under an axisymmetric power-law shaped punch is investigated. • The full analytical solutions for the coupled physical fields at the surface of multiferroic half-space are obtained. • The explicit analytical expressions of load-displacement relationship are derived for the first time. • The shape index has a significant effect on both the load-displacement relationship and distribution of generalized stress fields. Nanoindentation technique has been widely employed to characterize various material properties of multiferroic composite medium, where the indenter tip may have more general profile rather than just three common simple shapes (flat, cone and sphere). In this paper, the frictionless indentation problem of a transversely isotropic multiferroic half-space punched by an axisymmetric power-law shaped indenter is investigated. By virtue of the Hankel integral transform, the stated mixed boundary value problem is reduced to dual integral equations, which are then solved analytically. Closed-form solutions for the coupled physical fields at the surface of multiferroic half-space under the action of the power-law shaped indenters with four different electromagnetic properties are obtained, which can include the existing results in literature as special cases. The explicit analytical expressions of load-displacement relationship for the power-law shaped indenter are derived for the first time, which provide the theoretical foundation for characterizing material properties of multiferroic composite medium. The effects of the shape index and electromagnetic properties of the indenter on indentation behaviors are discussed in detail. It is found that the shape index has a significant effect on both the load-displacement relationship and the distribution of the generalized stress fields. The analytical solutions derived from this work can serve as benchmarks for experimental test and characterization of multiferroic composite materials. [ABSTRACT FROM AUTHOR]

The preparation of 2D magnetoelectric (ME) nanomaterials with strong ME coupling is crucial for the fast reading and writing processes in the next generation of storage devices. Herein, 2D BaTiO3 (BTO)‐CoFe2O4 (CFO) ME nanocomposites are prepared through a substrate‐free coupling strategy using supercritical CO2. Such 2D BTO‐CFO with strong coupling is built through alternating in‐plane and out‐of‐plane epitaxy stacking, leading to remarkable mutual biaxial strain effects for spin‐lattice coupling. As a results, such strain effect significantly enhances the ferroelectricity of BTO and the ferrimagnetism of CFO, where an unexceptionally high ME coupling coefficient of (325.8 mV cm−1 Oe−1) is obtained for the BTO‐CFO nanocomposites. [ABSTRACT FROM AUTHOR]

Multiferroic materials offer a promising avenue for manipulating digital information by leveraging the cross-coupling between ferroelectric and ferromagnetic orders. Despite the ferroelectricity has been uncovered by ion displacement or interlayer-sliding, one-unit-cell of multiferroic materials design and wafer-scale synthesis have yet to be realized. Here we develope an interface modulated strategy to grow 1-inch one-unit-cell of non-layered chromium sulfide with unidirectional orientation on industry-compatible c-plane sapphire. The interfacial interaction between chromium sulfide and substrate induces the intralayer-sliding of self-intercalated chromium atoms and breaks the space reversal symmetry. As a result, robust room-temperature ferroelectricity (retaining more than one month) emerges in one-unit-cell of chromium sulfide with ultrahigh remanent polarization. Besides, long-range ferromagnetic order is discovered with the Curie temperature approaching 200 K, almost two times higher than that of bulk counterpart. In parallel, the magnetoelectric coupling is certified and which makes 1-inch one-unit-cell of chromium sulfide the largest and thinnest multiferroics. 2D multiferroic materials have garnered broad interests due to their magnetoelectric properties and multifunctional applications. Here, the authors discover a multiferroic feature in interfacial modulation synthesized wafer-scale one-unit-cell Cr2S3. [ABSTRACT FROM AUTHOR]

For the development of spintronic devices, the control of magnetization by a low electric field is necessary. The microscopic origin of manipulating spins relies on the control of orbital magnetic moments (morb) by strain; this is essential for the high performance magnetoelectric (ME) effect. Herein, electric-field induced X-ray magnetic circular dichroism (XMCD) is used to determine the changes in morb by piezoelectric strain and clarify the relationship between the strain and morb in an interfacial multiferroics system with a significant ME effect; the system consists of the Heusler alloy Co2FeSi on a ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 substrate. Element-specific investigations of the orbital states by operando XMCD and the local environment via extended X-ray absorption fine structure (EXAFS) analysis show that the modulation of only the Fe sites in Co2FeSi primarily contributes to the giant ME effect. The density functional theory calculations corroborate this finding, and the growth of the high index (422) plane in Co2FeSi results in a giant ME effect. These findings elucidate the element-specific orbital control using reversible strain, called the 'orbital elastic effect,' and can provide guidelines for material designs with a giant ME effect. Schematic illustrations of the changes in the magnetic anisotropy by an applied electric field (E) in the strain directions are displayed. Under an applied E, the piezoelectric stress in the ferroelectric PMN-PT could be introduced in the tensile and compressive directions using positive and negative bias voltages, respectively, resulting in the changes in the magnetic anisotropy in the Co2FeSi layer. The XMCD spectra of Fe and Co L-edges in Co2FeSi under applying E showed the line shape changes only in the Fe site, which corresponds to the changes of orbital magnetic moment in Fe, while that in Co remains unchanged. [ABSTRACT FROM AUTHOR]

Magneto-mechano-electric (MME) generators efficiently harness ubiquitous stray magnetic fields and convert them into electricity, capturing significant attention for powering innumerable wireless sensors. In this study, lead-free 0-3 particulate magnetoelectric (ME) nano-composite ceramics, specifically x(Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3)-(1-x)Ni 0.5 Zn 0.5 Fe 2 O 4 [x(BCT-BZT)–(1-x)NZFO], were synthesized using the sol-gel method. Subsequently, a flexible MME generator was designed, incorporating the optimized ME composite. Structural parameter calculations indicated higher tetragonal distortion of 0.4% in 0.4(BCT-BZT)-0.6NZFO, possibly due to uniform particulate distribution. The ME composites displayed uniform dual-phase microstructures, with 0.4(BCT-BZT)-0.6NZFO showing a higher NZFO concentration. The maximum values of the magnetodielectric (MD) and ME coupling coefficients have been determined to be -3.6% and 2.55 mV cm -1 Oe-1, respectively, for an x = 0.4 composite. The MME generator is designed using an optimized 0.4(BCT-BZT)-0.6NZFO ME composite with film thickness of 34 μm. This MME generator harvests a sinusoidal wave with a maximum output peak-to-peak voltage of 4.1 V when exposed to a weak AC magnetic field of 10 Oe at a frequency of 50 Hz. Additionally, the device demonstrates an exceptional optimal DC power density of 3.89 μW cm-3. The lead-free 0-3 particulate ME composite enables effective magnetic energy harnessing. As a result, it holds great promise as an efficient autonomous power supply for various Internet of Things based applications. [ABSTRACT FROM AUTHOR]

Using the free (pressureless) sintering method, multiferroic ceramic composites based on two ferroelectric materials, i.e., BaTiO3 (B) and Pb0.94Sr0.06 (Zr0.46Ti0.54)0.99Cr0.01O3 (P), and magnetic material, i.e., zinc–nickel ferrite (F) were obtained. Three composite compositions (BP-F) were obtained with a constant 90/10 content (ferroelectric/magnetic) and a variable content of the ferroelectric component (B/P), i.e., 70/30, 50/50, and 30/70. Crystalline structure, microstructural, DC electrical conductivity, dielectric, and ferroelectric properties of multiferroic composites were investigated. The concept of a composite consisting of two ferroelectric components ensures the preservation of sufficiently high ferroelectric properties of multiferroic composites sintered by the free sintering method. Research has shown that the percentage of individual ferroelectric components in the composite significantly affects the functional properties and the entire set of physical parameters of the multiferroic BP-F composite. In the case of the dielectric parameters, the best results were obtained for the composition with a more significant amount of BaTiO3; i.e., permittivity is 1265, spontaneous polarization is 7.90 µC/cm2, and remnant polarization is 5.40 µC/cm2. However, the most advantageous set of performance parameters shows the composite composition of 50BP-F. [ABSTRACT FROM AUTHOR]

Owing to their remarkable success in photocatalytic applications, multiferroic BiFeO3 and its derivatives have gained a highly promising position as electrode materials for future developments of efficient catalysts. In addition to their appropriate band gaps, these materials exhibit inherent intrinsic polarizations enabling efficient charge carrier separation and their high mobility without the need for additional co-catalysts. Here, we review the existing strategies for enhancing the photocatalytic performances of BiFeO3-based materials and we describe the physico-chemical properties at the origin of their exceptional photocatalytic behavior. A special focus is paid to the degradation of organic pollutants and water splitting, both driven through photocatalysis to unveil the correlation between BiFeO3 size, substitution, and doping on the one hand and the photocatalytic performances on the other hand. Finally, we provide practical recommendations for future developments of high-performing BiFeO3-based electrodes. [ABSTRACT FROM AUTHOR]

Engineering piezo/ferroelectricity in two-dimensional materials holds significant implications for advancing the manufacture of state-of-the-art multifunctional materials. The inborn nonstoichiometric propensity of two-dimensional transition metal dichalcogenides provides a spiffy ready-available solution for breaking inversion centrosymmetry, thereby conducing to circumvent size effect challenges in conventional perovskite oxide ferroelectrics. Here, we show the extendable and ubiquitous piezo/ferroelectricity within nonstoichiometric two-dimensional transition metal dichalcogenides that are predominantly centrosymmetric during standard stoichiometric cases. The emerged piezo/ferroelectric traits are aroused from the sliding of van der Waals layers and displacement of interlayer metal atoms triggered by the Frankel defects of heterogeneous interlayer native metal atom intercalation. We demonstrate two-dimensional chromium selenides nanogenerator and iron tellurides ferroelectric multilevel memristors as two representative applications. This innovative approach to engineering piezo/ferroelectricity in ultrathin transition metal dichalcogenides may provide a potential avenue to consolidate piezo/ferroelectricity with featured two-dimensional materials to fabricate multifunctional materials and distinguished multiferroic. Nonstoichiometric transition metal dichalcogenides break symmetry, enabling piezo/ferroelectric effects. Here, the authors propose an approach to integrate these properties with diverse 2D materials, advancing multifunctional materials and devices. [ABSTRACT FROM AUTHOR]

Multiferroic materials have recently attracted great attention for possible use in photovoltaic and photocatalytic devices. In this study, pure-phase BiFe 1- x Mn x O 3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) thin films were deposited on glass substrates via low-temperature sol-gel assisted spin coating procedure. We found that the thin films undergo a rhombohedral to cubic structural transition. From FESEM images, it was observed that different amount of Mn affects the surface morphology and grain size of the studied samples. For all samples, the absorption coefficient was in the range of 105 cm−1, and the refractive index and extinction coefficient of samples were about 1.15–1.50 and 0.2–0.9, respectively. BiFe 0.8 Mn 0.2 O 3 thin film has the lowest bandgap energy due to the highest absorption coefficient at the wavelengths of 400–1100 nm denoted by its lowest transmittance. Structural and magnetic results show the substitution of low-spin smaller Mn ions for high-spin larger Fe ions. The best photocatalytic activity was observed for BiFe 0.8 Mn 0.2 O 3 thin film with a removal efficiency of 78.83% in the photodegradation of methylene blue. [ABSTRACT FROM AUTHOR]