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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]

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]

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

We present a strategy for realizing the nonvolatile electrical control of noncollinear magnetism based on first-principles calculations. We confirm that the VAl2S4 monolayer, a rare two-dimensional type-II multiferroic material, shows an in-plane noncollinear 120°-ordered antiferromagnetic ground state and spin spiral order induced out-of-plane ferroelectricity. In VAl2S4 bilayers, we clarify the spin spiral chirality–sliding ferroelectricity locking effect, which enables flexible electrical switching of noncollinear magnetism and corresponding spin spiral chirality through interlayer sliding. Our work provides another perspective for the development of magnetoelectric physics and information storage devices. [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]

BiFeO3 is a multiferroic material, its tetragonality (T) phase usually exhibits large tetragonality (c/a ratio) and strong ferroelectricity. Unlike the commonly used method of strain engineering via substrate, here we present a general and practical approach for obtaining T-like phase BiFeO3 films through (Ba,Ca)TiO3 doping (BF-BCT). The BF-BCT film coherently grows on the La0.7Sr0.3MnO3/(La0.18Sr0.82)(Al0.59Ta0.41)O3 (001) substrate even at 180 nm thick, implying a very large critical thickness, and shows a large tetragonality of 1.12. Impressively, the films exhibit a giant remanent polarization (2Pr) of 320 μC/cm2, which is higher than the corresponding values of any other lead-free ferroelectric films reported to date. Cross-sectional scanning transmission electron microscopy measurements confirm the presence of the T-like phase in BF-BCT films, where the giant polarization might be attributed to the off-center B-site atom. The BF-BCT films are structurally homogeneous without any precipitation of the second phase. The giant polarization observed in the BF-BCT films indicate their great potential for application in next-generation storage and information devices. [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]

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]

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]

Thin-film ferroelectrics have been pursued for capacitive and nonvolatile memory devices. They rely on polarizations that are oriented in an out-of-plane direction to facilitate integration and addressability with complementary metal-oxide semiconductor architectures. The internal depolarization field, however, formed by surface charges can suppress the out-of-plane polarization in ultrathin ferroelectric films that could otherwise exhibit lower coercive fields and operate with lower power. Here, we unveil stabilization of a polar longitudinal optical (LO) mode in the n = 2 Ruddlesden-Popper family that produces out-of-plane ferroelectricity, persists under open-circuit boundary conditions, and is distinct from hyperferroelectricity. Our first-principles calculations show the stabilization of the LO mode is ubiquitous in chalcogenides and halides and relies on anharmonic trilinear mode coupling. We further show that the out-of-plane ferroelectricity can be predicted with a crystallographic tolerance factor, and we use these insights to design a room-temperature multiferroic with strong magnetoelectric coupling suitable for magneto-electric spin-orbit transistors. [ABSTRACT FROM AUTHOR]

Multiferroic materials have ignited enormous interest owing to their co-existence of ferroelectricity and ferromagnetism, which hold substantial promise for advanced device applications. However, the size effect, dangling bonds, and interface effect in traditional multiferroics severely hinder their potential in nanoscale device applications. Recent theoretical and experimental studies have evidenced the possibility of realizing two-dimensional (2D) multiferroicity in van der Waals (vdW) layered CuCrP2S6. However, the incorporation of magnetic Cr ions in the ferroelectric framework leads to antiferroelectric and antiferromagnetic orderings, while macroscopic spontaneous polarization is always absent. Herein, we report the direct observation of robust out-of-plane ferroelectricity in 2D vdW CuCrP2S6 at room temperature with a comprehensive investigation. Modification of the ferroelectric polarization states in 2D CuCrP2S6 nanoflakes is experimentally demonstrated. Moreover, external electric field-induced polarization switching and hysteresis loops are obtained in CuCrP2S6 down to ~2.6 nm (4 layers). By using atomically resolved scanning transmission electron microscopy, we unveil the origin of the emerged room-temperature ferroelectricity in 2D CuCrP2S6. Our work can facilitate the development of multifunctional nanodevices and provide important insights into the nature of ferroelectric ordering of this 2D vdW material. CuCrP2S6 is a potential candidate for realizing low-dimensional multiferroicity. Here, authors report direct observation of robust out-of-plane ferroelectricity in the two-dimensional van der Waals layered CuCrP2S6 at room temperature down to 2.6 nm and study its origin from an atomic perspective. (299 in total) [ABSTRACT FROM AUTHOR]

We study the structural, electronic, and magnetic properties of the SrCrO3/YCrO3 superlattice and their dependence on epitaxial strain. We discover that the superlattice adopts A-type antiferromagnetic (A-AFM) ordering in contrast to its constituents (SrCrO3: C-AFM; YCrO3: G-AFM) and retains it under compressive strain while becoming ferromagnetic (5 μB per formula unit) at +1% strain. The obtained ferroelectric polarization is significantly higher than that of the R2NiMnO6/La2NiMnO6 (R = Ce to Er) series of superlattices [Nat. Commun. 5, 4021 (2014)] due to a large difference between the antipolar displacements of the Sr and Y cations. The superlattice is a hybrid-improper multiferroic material with a spontaneous ferroelectric polarization (13.5 μC/cm2) approaching that of bulk BaTiO3 (19 μC/cm2). The combination of ferromagnetism with ferroelectricity enables multistate memory applications. In addition, the charge-order-driven p-type semiconducting state of the ferromagnetic phase (despite the metallic nature of SrCrO3) is a rare property and interesting for spintronics. Monte Carlo simulations demonstrate a magnetic critical temperature of 90 K for the A-AFM phase without strain and of 115 K for the ferromagnetic phase at +5% strain, for example. [ABSTRACT FROM AUTHOR]

Single-phase multiferroic materials of rare-earth orthoferrites with magnetism and ferroelectricity are of great technological importance in storage devices. However, the polarization (P) of these materials is generally weak (0.01 μC·cm−2), and the ferroelectricity is reported to exist below room temperature (25 ℃). Here, (Bi0.2La0.2Y0.2Dy0.2Tb0.2)FeO3 (BLYDTFO) high-entropy oxides that exhibit a saturation P of 5.3 μC·cm−2 at the electric field (E) of 45 kV·cm−1 at room temperature was designed and fabricated by the conventional solid-phase method. The results show that configurational entropy introduces atomic disorder and a larger tilt of BO6 octahedron, which facilitates non-centrosymmetric distortion and ferroelectricity at room temperature compared with other single components (LaFeO3, YFeO3, DyFeO3, and TbFeO3). This high-entropy approach expands the compositional window of the rare-earth orthoferrites to enhance the ferroelectricity in multiferroic applications.

The contrasting d-orbital occupation required for ferroelectricity vs ferromagnetism makes it difficult for their coexistence in two-dimensional materials, especially at high temperature. To resolve this intrinsic contradiction, we propose a layered MoCr2S6 multiferroics by alloying magnetic Cr element into the ferroelectric 1T phase of the MoS2 matrix. First-principles calculations disclose that a spontaneous symmetry breaking, depending on the Mo atom displacement, leads to a robust ferroelectricity, which coexists with a ferromagnetic order originated from two neighboring Cr atoms. The effect can be further enhanced by tensile strain to bring about a room-temperature multiferroicity. Our findings shed new light on the fundamental understanding of multiferroics and display promising applications in spintronics and multistate data storage. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) multiferroic materials with coexisting ferroelasticity (FA) and ferroelectricity (FE) have potential applications in high-density data storage and sonar detectors. Here, based on first-principles calculations, we predict a series of stable 2D FA-FE multiferroic structures, namely, γ-XOOH (X = Al, Ga, and In) monolayers. By analyzing the lattice symmetry and orientation distribution of hydroxyls, we find that XOOH monolayers possess both in-plane ferroelastic and ferroelectric polarization, as well as antiferroelectric ordering caused by the anti-parallel alignment of hydroxyls. Interestingly, the perpendicular reorientation of in-plane FE polarization accompanies 90° ferroelastic switching. Moreover, they show an unusual negative transverse piezoelectric effect originated from the clamped-ion term. The multiferroic properties of the XOOH monolayers provide an excellent platform to study electroelastic effects. [ABSTRACT FROM AUTHOR]

Multiferroic composites offer promising prospects for low-power multifunctional devices. Here, we report the structural, electrical, dielectric, magnetic, and magnetodielectric properties of the multiferroic composite material (1 − x)LiNbO3–xLa0.9Na0.1MnO3 (where x = 0.1, 0.2, and 0.3). Ferroelectric and magnetic phases were synthesized using citrate gel method and the conventional solid-state reaction method was used for the preparation of multiferroic composite material with different mixing percentage values of x. X-ray diffraction was used to confirm the crystalline purity and the crystal structure of the material. The microstructural and elemental composition analyses were done by FE-SEM, X-ray photon spectroscopic (XPS), and EDAX techniques. Dielectric studies and impedance analysis imply the dynamic behavior of charge carriers inside the composites. The maximum value of dielectric constant (5000) was obtained at x = 0.3 for xLa0.9Na0.1MnO3 phase. From impedance analysis method, the equivalent circuit of (1 − x)LiNbO3–xLa0.9Na0.1MnO3 (where x = 0.1, 0.2, and 0.3) composite was found out. The P–E hysteresis loop reveals the ferroelectric nature of the composite. Sample with x = 0.1 of xLa0.9Na0.1MnO3 phase gives the highest values for maximum polarization and remnant polarization. The enhanced magnetic properties of the composite material were substantiated with M–H hysteresis loop measurements. The magnetodielectric and magnetoelectric coupling measurements revealed the presence of ferroelectric and ferromagnetic coupling nature of the composite material. From all these analyses, the multiferroic composites with the composition x = 0.3(La0.9Na0.1MnO3) yields the maximum ferroelectric and magnetic coupling behavior. So, this composite material has wide applications in multifunctional nano devices. [ABSTRACT FROM AUTHOR]

One‐dimensional (1D) magnetoelectric multiferroics are promising multifunctional materials for miniaturized sensors, actuators, and memories. However, 1D materials with both ferroelectricity and ferromagnetism are quite rare. Herein, using first‐principles calculations, a series of fullerene‐based 1D chains, namely U2C@C80‐M (M = Cr, Mn, Mo, and Ru) 1D chains with both ferroelectric (FE) and ferromagnetic (FM) properties is designed. Compared to individual U2C@Ih(7)‐C80, the spontaneous polarization (Ps) in 1D chains is enhanced by about two to four times owing to the interaction between U2C@Ih(7)‐C80 fullerene and M (M = Cr, Mn, Mo, and Ru) atoms. Meanwhile, the introduction of transition metal atoms dopes electrons into U's 5f orbitals, leading to numerous intriguing magnetic properties, such as U2C@C80‐Cr and U2C@C80‐Mo as 1D ferromagnetic semiconductors, U2C@C80‐Ru as 1D ferrimagnetic (FiM) semiconductor, and U2C@C80‐Mn as 1D antiferromagnetic (AFM) semiconductor. Excitingly, it is found that magnetic ordering and electrical polarization can be modulated independently by linking different transition metal atoms. These findings not only broaden the range of 1D multiferroic materials, but also provide promising candidates for novel electronic and spintronic applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) multiferroic materials combining intrinsic ferroelectricity, ferromagnetism, and ferroelasticity, which promise piezo-magnetoelectric effects, are highly desired for their potential applications in high-density and multi-functional spintronic devices. However, a room-temperature 2D triferroic semiconductor has never been reported. Here, on the basis of first-principle calculations, we predict that the CrNCl monolayer is a potential 2D triferroic semiconductor with ferroelectricity, ferromagnetism, and ferroelasticity coexisting and strongly coupling at room temperature. The strong d-p hybridizations between Cr and N ions give rise to Cr–N dimerizations, leading to spontaneous symmetry-breaking and an in-plane electric polarization, as well as a remarkable enhancement of ferromagnetic super-exchange interactions. Moreover, the ferroelastic transition is accompanied by a 90° rotation of the in-plane electric polarization and the magnetic easy axis, suggesting a strong piezo-magnetoelectric effect. These findings provide insights into multiferroic behaviors in 2D systems and can help facilitate further advancements in spintronics. [ABSTRACT FROM AUTHOR]

Single‐phase multiferroics suffer from a fundamental contradiction between polarity and magnetism in d0 electronic configuration, motivating studies of unconventional ferroelectricity in magnetic oxides. However, low critical temperature and polarization still need to be overcome. Here, it is reported that the switchable polarization behavior at room temperature in [(La2NiMnO6)/(La2CoMnO6)]n double‐perovskite magnetic superlattice films is achieved by engineering a microstructure with gradient strains, and the ferromagnetic Curie temperature did not show a rapid decrease. The synergy of gradient strains and superlattice components plays a decisive role in inducing ferroelectricity via the tilting or rotation of various oxygen octahedra. Such distortion responses to gradient strains are accompanied by slight magnetic fluctuations, maximizing the preservation of the initial magnetic exchange interactions, which alleviates the contradiction of multiferroic coexistence to a certain extent. This work confirms the room‐temperature ferroelectricity in double‐perovskite superlattices and provides a preferred strategy for confronting the difficulty of multiferroic coexistence in single‐phase materials. [ABSTRACT FROM AUTHOR]

Improper ferroelectrics are a class of materials with the potential to design multiferroic properties. In this paper, we report on the effect of defect dipoles on the ferromagnetic and ferroelectric properties of Ca 3 Mn 2 O 7 improper ferroelectric thin films. Two kinds of defects dipoles, Mn3+-oxygen vacancy (Mn3+- V O ∙ ∙ ) and Li+-Al3+ doping, were studied. The experimental results show that both Mn3+- V O ∙ ∙ and Li+-Al3+ defect dipoles can introduce ferromagnetism in the films, and Li+-Al3+ defect dipole can also improve ferroelectricity with self-polarization. The first-principle calculations based on local density approximation demonstrate the local lattice distortion, including title MnO 6 octahedron and off-center displacement of Mn ion, plays crucial role in multiferroic properties of the film. This work gives an effective method to design the ferroelectricity and ferromagnetic properties in improper ferroelectric oxides with layered structure through constructing defect dipoles. [ABSTRACT FROM AUTHOR]

Multiferroic materials have attracted significant research attention due to their technological potential for applications as multifunctional devices. The scarcity of single-phase multiferroics and their low inherent coupling between multiferroic order parameters above room temperature pose a challenge to their further applications. We propose a 3BiFeO3/7BaTiO3 perovskite–perovskite composite that combines ferroelectricity and ferromagnetism. We demonstrate that the sintering temperature can tailor the ferroelectricity and ferromagnetism of the composites. The multiferroicity can be achieved at a low sintering temperature in the composite-like structure ceramics, and its multiferroic properties, especially the ferromagnetism, are superior to those of solid solutions. We also investigate the dynamic evolution of multiferroicity with sintering temperature. We adopt a nano–micro strategy to construct a composite-like microstructure, which results in optimized ferroelectric (1.62 μC cm−2) and ferromagnetic (0.16 emu/g) characteristics at a sintering temperature of 750 °C. We also found experimental evidence of the competition between antiferromagnetic and ferromagnetic interactions in the transition metal cation sublattice. Multiferroic BiFeO3/BaTiO3 composites with combined ferroelectric and ferromagnetic properties have significant potential for various applications. [ABSTRACT FROM AUTHOR]

Hydrogen is a potential future energy source that could replace conventional fuel and provide the necessary energy. Multiferroic materials are the most likely choices for water splitting due to their ferroelectric characteristics and ability to function as magnetically recoverable catalysts. Multiferroic terbium orthoferrite nanoparticles were synthesized at low temperature by the polymeric citrate precursor route to study the photocatalytic, electrocatalytic and photoelectrochemical activity towards hydrogen production. Powder X-ray diffraction revealed successful formation of orthorhombic TbFeO 3 nanoparticles. A larger aspect ratio of 3.9 and a bandgap of 2.13 eV were seen in the elongated TbFeO 3 nanoparticles, which contributes to the photo/electro-catalytic activity. Magnetic and ferroelectric studies revealed weak ferromagnetism and ferroelectric polarization of 0.037 μC cm−2 in TbFeO 3 nanoparticles, confirming multiferroicity. Visibly active and multiferroic TbFeO 3 nanoparticles showed notable hydrogen evolution of 1.44 mmol h−1 g−1. In electrocatalytic and photoelectrochemical water splitting investigations, TbFeO 3 nanoparticles demonstrated current densities of 30 and 60 mA cm−2, respectively. EIS, TRPL, transient photocurrent and Mott-schottky measurements were used to examine charge transfer kinetics. The high H 2 evolution and good OER/HER tests were attributed to increased charger separation efficiency due to ferroelectricity induced band bending. [Display omitted] • Multiferroic orthorhombic TbFeO 3 NPs stabilized by low temperature precursor route. • Morphological studies show elongated nanoparticles with aspect ratio of 3.9. • Significant photocatalytic H 2 evolution rate of 1.44 mmol h−1 g−1. • High OER/HER/photocurrent density in TbFeO 3 NPs is reported. [ABSTRACT FROM AUTHOR]

Sliding ferroelectricity (SFE) found in two-dimensional (2D) van der Waals (vdW) materials, such as BN and transition-metal dichalcogenides bilayers, opens an avenue for 2D ferroelectric materials. Multiferroic coupling in 2D SFE materials brings us an alternative concept for spintronic memory devices. In this study, using first-principles calculations, we demonstrate that MnSe multilayers constructed by the recently-synthesized MnSe monolayer have large sliding-driven reversible out-of-plane electric polarization (~10.6 pC m−1) and moderate interlayer sliding barriers superior to the existing 2D SFE materials. Interestingly, the intrinsic electric polarization is accompanied by nonzero net magnetic moments which are also switchable via lateral interlayer sliding. Additionally, both SFE and magnetoelectric coupling can be effectively regulated by external strain and/or hole doping. Our findings suggest the potential of MnSe multilayers in 2D multiferroic and spintronic applications. [ABSTRACT FROM AUTHOR]

Multiferroic materials with coexisting ferroelectric and ferromagnetic orders have attracted much attention due to the magnetoelectric coupling opening alternative prospects for electronic devices. Composite multiferroics containing separate ferroelectric and ferromagnetic components are a promising alternative to the single-phase counterparts. Composite multiferroic structures comprising HfO2-based ferroelectrics are potentially feasible for technological applications. Here, this study reports on the experiments aiming at the manifestation of magnetoelectric coupling at Fe/Hf0.5Zr0.5O2 (HZO) interface. Using synchrotron based 57Fe Mössbauer spectroscopy technique in operando, this study probes element-selectively the local magnetic properties of a nanometer-thick enriched 57Fe marker layer in functional Pt/57Fe/HZO/TiN capacitors and demonstrates the evidence of the ferroelectric polarization effect on the a-Fe magnetic response. Besides a-Fe exhibiting a magnetoelectric coupling, both ferromagnetic and superparamagnetic Fe3O4 components are found in the Mössbauer spectra, apparently originating from the oxygen or OH- ions penetrating ultrathin Pt overlayer during crystallization annealing of HZO. The observed effect as well as the electronic band lineup of the Fe/HZO interface elucidated from synchrotron based hard X-ray photoemission spectroscopy measurements are interpreted in terms of charge-mediated magnetoelectric coupling at the Fe/HfO2 interface driven by ferroelectric HZO polarization reversal. [ABSTRACT FROM AUTHOR]

Ca 3 (Ti 1- x Co x) 2 O 7 ceramics were prepared by a tartaric acid sol-gel method and sintered in an oxygen atmosphere. The introduction of Co2+/Co3+ as acceptor dopants leads to the formation of more oxygen vacancies and defect dipoles in Ca 3 (Ti 1- x Co x) 2 O 7 ceramics. Oxygen vacancy and defect dipoles lead to the transition of dielectric, leakage, and ferroelectric behaviors of Ca 3 (Ti 1- x Co x) 2 O 7 ceramics. The coexistence of hybrid improper ferroelectricity and ferromagnetism at room temperature in Ca 3 (Ti 1- x Co x) 2 O 7 ceramics has been successfully realized through the superexchange interaction of Co–O–Co. Ca 3 (Ti 1- x Co x) 2 O 7 ceramics exhibit superior ferroelectricity (the remnant polarization is 3.29 μC/cm2) and enhanced ferromagnetism (the remnant magnetization reaches 6.4×10−3 emu/g). This strategy based on the introduction of transition metal ions with unfilled 3d shells at B sites is an important approach to realize novel room-temperature single-phase multiferroic materials for Ca 3 Ti 2 O 7 -based materials. [ABSTRACT FROM AUTHOR]

BiFeO3 represents the most extensively investigated multiferroic due to its fascinating ferroelectric domain structures, large polarization, and multiferroic coupling, among many other emergent phenomena. Nevertheless, much less concern with the piezoelectricity has been raised while all these well addressed properties are identified in thin film BiFeO3, and bulk ceramic BiFeO3 has never been given priority of attention. In this paper, we report our experiments on the ferroelectric and piezoelectric properties as well as domain structures of BiFeO3 bulk ceramics synthesized by rapid hot-press sintering. It is revealed that these properties are strongly dependent on the microstructural quality, and the largest piezoelectric coefficient d33 = 55 pC/N with electric polarization as large as 45 μC/cm2 is obtained for the sample sintered at 800 °C, while they are only 30 pC/N and 14 μC/cm2 for the samples sintered in normal conditions at 800 °C. The two-level hierarchical stripe-like and irregular dendrite-like domain structures are observed in these hot-press sintered samples. It is suggested that the enhanced piezoelectric property is ascribed to the two-level hierarchical stripe-like domain structure which may respond more easily to electrical and strain stimuli than those irregular dendrite-like domains. The enhanced remnant polarization should be owing to the improved sample quality and large grains in the properly hot-press sintered samples. [ABSTRACT FROM AUTHOR]

Multiferroic composites of (1-x)GaFeO3-(x)Co0.5Zn0.5Fe2O4 with x = 0.0, 0.1, 0.2, and 1 were prepared using a conventional solid state reaction method. The X-ray diffraction patterns confirmed that the composites consisted of cubic spinel Co0.5Zn0.5Fe2O4 and orthorhombic GaFeO3 phases. The coexistence of both magnetic and ferroelectric orderings at ambient temperature was confirmed by measuring M-H and P-E loops. The inclusion of Co0.5Zn0.5Fe2O4 enhanced magnetization and dielectric constant, as well as improved the ferroelectric properties of GaFeO3. The leakage current (9.33 × 10−8 A/cm2) of composite (x = 0.20) is found to be much lower as compared to pure GaFeO3. The value of saturation magnetization increased to 30.6 emu/g at 300 K. This large enhancement of magnetization, as well as the presence of ferroelectricity, is promising for enabling future magnetoelectric applications. [ABSTRACT FROM AUTHOR]

Optical second harmonic generation (SHG) is a sensitive and powerful technique to probe various symmetry breaking, especially ferroelectric/magnetic domains, in artificial thin films or heterostructures. In a wide range of ferroelectric crystals, a non‐trivial broken symmetry will emerge at domain boundaries, however, the contribution of such symmetry breaking to SHG is often neglected due to its random orientation. Here, a co‐polarized SHG effect from the well‐aligned domain wall arrays is observed in BiFeO3 thin films. This SHG component is highly dependent on the local orientation of the wall arrays, and its polarization feature reveals the Néel‐like evolution of electric polar vectors in the wall region. Based on this intriguing effect, mixed‐phase patches with four possible orientations in the quasi‐tetragonal stripes are identified by polarization‐sensitive SHG mapping. These findings not only clarify a critical SHG contribution in this multiferroic material, but also demonstrate an optical approach for exploring phase‐determined function unit. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) materials provide the versatile playground to stack two or more vdW layers for creation of superior materials with desired properties. Here we theoretically adopt a twisted stack-engineering of two LaBr2 monolayers to break space inversion symmetry for ferroelectricity and ultimately multiferroism. The enhancement and reversal of electric polarization are accompanied with the transition from interlayer ferromagnetic and antiferromagnetic orderings, demonstrating an effective magnetoelectric coupling effect with a mechanism dissimilar to that of the conventional multiferroics. Magnetization dynamics simulations show that such magnetic phase transition can excite topologically protected bimeron, and the skyrmion Hall effect can be suppressed by bilayer-bimeron stabilized in both ferromagnetic and antiferromagnetic configurations. Moreover, in the small-angle twisted moiré superlattice, the uniform polarization will evolve into a staggered domain structure, accompanied with the appearance of bimeron, which forms a significant discrepancy with the non-twisted stack-engineered multiferroic LaBr2 bilayer. This work provides a strategy for 2D multiferroic materials by twisted stack engineering of magnetic single layers. [ABSTRACT FROM AUTHOR]

Ferroelectric and magnetic properties are investigated for Bi2Fe4O9 nanoparticles with different shapes (cuboid and sphere-like) synthesized by hydrothermal and sol-gel method. The magnetic study reveals that coercivity, Neel temperature and remanent magnetization strongly depend on shape of the particle. The nanoparticle with sphere-like shape exhibits magnetization curve of antiferromagnetic (AFM) ordering with ferromagnetic (FM) component. As the particle shape changes from sphere-like to cuboid, the AFM component is dominating over the ferromagnetic component. A small exchange bias is also observed at low temperature in both the sphere-like and cuboid nanoparticle. The coercivity, remanent magnetization and Neel temperature of sphere-like nanoparticle is greater than cuboid nanoparticle. Ferroelectric measurement shows the remanent polarization of cuboid is greater than sphere-like nanoparticle but the coercivity is almost same. This Bi2Fe4O9 nanoparticle shows a small change in polarization under magnetic field. The polarization value decreases with magnetic field increases. The magnetoelectric coupling-measured by change of remanent polarization under magnetic field are found to be greater in Bi2Fe4O9 sphere-like nanoparticles. These shape dependent magnetic and ferroelectric properties are coming because of shape anisotropy. [ABSTRACT FROM AUTHOR]

Multiferroic ceramics with composition (1 − x) BaFe12O19–(x)BaTiO3; (x = 0, 0.2, 0.5, 0.8 and 1) were fabricated through solid-state reaction. X-ray diffraction (XRD) analysis confirmed the synthesis of composite samples with the coexistence of ferroelectric and ferromagnetic phases. Rietveld refinement patterns revealed the presence of cubic phase besides tetragonal phase in pure ferroelectric (BaTiO3). Field emission scanning electron microscope (FESEM) with energy dispersive X-ray spectroscopy (EDX) used to have morphological studies and compositional analysis. Average grain size decreased and dielectric constant increased upon adding ferroelectric phase in hexaferrite. Both tangent loss (tanδ) and dielectric constant exhibited dispersion at high temperature and low frequency. P–E loop confirmed the introduction of ferroelectric properties in hexaferrite upon adding BaTiO3. M–H loop confirmed magnetic behavior with high coercivity in composites at room temperature. The composite with x = 0.2 has a maximum magnetoelectric coupling coefficient at Hac = 45 Oe. The developed composites confirmed to possess multiferroic behavior and can be utilized as fabricating materials for magnetic recording and memory storage devices. [ABSTRACT FROM AUTHOR]

Magnetic Weyl semimetals Mn3Sn compound have appealing prospects for spintronic applications due to their various crystal structures and magnetic properties for the design of reliable high-density memories. This work presents the effect of tensile and compressive strains on the structural, electronic, magnetic, ferroelectric, optic, and magneto-optical properties of the Mn3Sn compound. Firstly, the first-principles calculations reveal an enormous ferroelectric effect with metallic behaviour. Secondly, we perform an analysis of the magneto-optical Kerr effect (MOKE) at stained thin-film, an important MOKE effect was found in an antiferromagnetic (AFM) ground state following along the direction [001] which is in good agreement with the experimental studies. Our results improve the theoretical understanding of the Dzyaloshinskii–Moriya interactions (DM) induced a large magneto-optical Kerr effect (MOKE). Also, the relationship between ferroelectric and ferromagnetic was investigated and should provide a basis for the experimental application of spintronic devices based on the anomalous Hall effect. [ABSTRACT FROM AUTHOR]

Development of multiferroic materials with the capability of compatibility with the current semiconductor technology is of interest for practical applications. Recent experimental discovery of robust ferroelectricity in CMOS-compatible III-nitrides offers an alluring opportunity to construct multiferroic nitrides through chemical-doping engineering. We here reported the coexistence of ferroelectricity and ferromagnetism in Ni-doped Al0.7Sc0.3N thin films. It is found that apart from the promising ferroelectric properties, including a square-like polarization–electric field (P–E) hysteresis loop with a large coercive field (∼3 MV/cm) and high remanent polarizations (∼100 μC/cm2), the films also exhibit room-temperature ferromagnetism, with a saturation magnetization of ∼8 emu/cm3. Additionally, the magneto-dielectric effect has also been experimentally confirmed. Our work provides a reference for subsequent research on nitride multiferroic materials and related applications. [ABSTRACT FROM AUTHOR]

Its an absolute pleasure to be able to write this article to honor Professor John Goodenough on his 100th birthday. John, here is wishing you many more years of wonderful science with mirth and laughter! I have had the pleasure of knowing John for more than two decades and also following in his footsteps (albeit at a great distance from him), working on complex correlated oxides for my entire professional career, starting from the Hi-TC cuprates, manganites that display colossal magnetoresistance, ferroelectricity and most recently looking at the coupling between electricity and magnetism in multiferroics as well as the intricacies of spin transport in correlated oxides. This article is written on behalf of many colleagues, collaborators, and researchers in the field of complex oxides as well as current and former students and postdocs who continue to enable and undertake cutting-edge research in the field of multiferroics, magnetoelectrics, and broadly correlated electron materials physics as well as the pursuit of electric-field control of magnetism. What I present is something that is extremely exciting from both a fundamental science and applications perspective and has the potential to revolutionize the field of microelectronics. To realize this potential will require numerous new innovations, both in the fundamental science arena as well as translating these scientific discoveries into real applications. Thus, this article attempts to bridge the gap between fundamental materials physics and the actual manifestations of the physical concepts into real-life applications, a spirit that John’s entire career has embraced. [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]

Multiferroics, coupling magnetism with electric polarization, provides special opportunities for both fundamental research and device applications. The current multiferroic research in a two-dimensional lattice is invariably focused on d-orbital based systems. We alternatively show by first-principles calculations that ideal multiferroics is present in a p-orbital based lattice of single-layer SiN. Single-layer SiN is a semiconductor exhibiting intrinsic ferromagnetism and ferroelectricity simultaneously. Its magnetism correlates with the extended p–p interaction between unpaired p orbitals of N atoms. The buckled symmetry guarantees the existence of an out-of-plane electric dipole, giving rise to the ferroelectric order. More remarkably, the ferroic orders in single-layer SiN display strongly coupled physics, i.e., the spatial distribution of magnetic moments can be well controlled by the reversal of electric polarization, thereby establishing the long-sought multiferroics with strong magnetoelectric coupling. These findings not only enrich a two-dimensional multiferroic family, but also enable a wide range of device applications. [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]

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]

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]

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]

The Bi1−xBaxFeO3 (BiBaFeO3) multiferroic nanoparticles with different Ba molar concentrations were fabricated in reliance on the solid-state reaction technique. Nanostructures of the prepared samples were confirmed by X-ray diffraction (XRD) together with Fourier transforms infrared (FTIR) spectroscopy, whereas the ac conductivity, dielectric and ferroelectric features were examined depending on the RLC Bridge, and Sawyer–Tower circuit. XRD patterns displayed the creation of rhombohedral–hexagonal single-phase of BiBaFeO3. The formation of BiBaFeO3 multiferroic nanoparticles was confirmed by FTIR spectra. Curie temperature (TC) was observed around 1121–1189 K. Ferroelectric polarization was enhanced with remnant polarization of 88.8 μC cm−2 by Ba2+ ions substitution at x = 0.15 mol%. Besides, ac electrical conductivities as a function of frequency as well as temperature were reported for all BiBaFeO3 multiferroic nanoparticles, which exhibit a strong frequency dependence with conduction mechanism is the correlated barrier hopping (CBH) model. The obtained high polarization and Curie temperature enhance their use in information storage devices. [ABSTRACT FROM AUTHOR]

The study of the functional properties of the multilayer composite films of ferroelectric (Bi0.5Na0.5)0.945Ba0.055TiO3 (BNBT) and multiferroic BiFeO3 (BF) obtained by chemical solution deposition has been performed in this work. First, it has been observed a significant improvement of the remnant polarization of the multilayer composite with respect to the single phase film of BNBT: Pr=32 µC×cm-2, which is comparable with the values reported for bulk BNBT. This is a consequence of the stabilization of the ferroelectric domains of BNBT, although the relaxor character is still present. The leakage currents, which prevent the full exploitation of the properties of BF films, are reduced thanks to the combination with insulator BNBT layers. Besides, the magnetic behavior shows values of remnant magnetization at room temperature that makes this multilayer composites promising for multiferroic applications. [ABSTRACT FROM AUTHOR]

The study of the functional properties of the multilayer composite films of ferroelectric (Bi0.5Na0.5)0.945Ba0.055TiO3 (BNBT) and multiferroic BiFeO3 (BF) obtained by chemical solution deposition has been performed in this work. First, it has been observed a significant improvement of the remnant polarization of the multilayer composite with respect to the single phase film of BNBT: Pr=32 µC×cm-2, which is comparable with the values reported for bulk BNBT. This is a consequence of the stabilization of the ferroelectric domains of BNBT, although the relaxor character is still present. The leakage currents, which prevent the full exploitation of the properties of BF films, are reduced thanks to the combination with insulator BNBT layers. Besides, the magnetic behavior shows values of remnant magnetization at room temperature that makes this multilayer composites promising for multiferroic applications. [ABSTRACT FROM AUTHOR]

Investigation of crystal structure, microstructure, local ferroelectric, and magnetic properties of the aliovalent-doped Bi0.95Ca0.05Fe1-yByO3 (B=Ti and Mn; y=0, 0.05, 0.1) perovskites has been carried out at room temperature to illustrate the role of anion vacancies in the suppression of cycloidal antiferromagnetic order taking place in the polar (x⩽0.1) phase of Bi1-xCaxFeO3-2/x multiferroics upon Ca2+ substitution. The compounds have been shown to possess the noncentrosymmetric rhombohedral structure specific to the parent Bi0.95Ca0.05FeO2.975.B-site substitution eliminating the oxygen vacancies suppresses a weak ferromagnetic contribution characteristic of the low-doped Bi1-xCaxFeO3-2/x ferrites. Over-compensatory Ti4+ doping (resulting in the appearance of cation vacancies in the host lattice) restores the weak ferromagnetic phase. The lattice defects dramatically affect both microstructure and ferroelectric domain structure of the Bi0.95Ca0.05Fe1-yByO3 perovskites and tend to decrease an average size of crystal grains and ferroelectric domains. These observations pave the way for understanding the conditions favoring the coexistence of spontaneous magnetization and polarization in BiFeO3-based multiferroics. [ABSTRACT FROM AUTHOR]