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Ferroelectric materials play a pivotal role in various industrial and scientific applications due to their ability to exhibit spontaneous electric polarization above a critical temperature. The application of a sufficiently high external electric field can induce the switching of the spontaneous polarization, with the specific mechanism varying across different materials. Understanding the intrinsic switching mechanism is paramount for regulating polarization domains, thereby unlocking potential applications in nanoelectronic devices. Different types of switching mechanisms have been experimentally reported and various models have been developed, among them the nucleation-limited-switching (NLS) model, which is distinguished by nucleation and limited propagation. We investigate the intrinsic polarization switching mechanisms in PbTiO 3 and Pb(Zr,Ti)O 3 using molecular dynamics simulations. We found that both PbTiO 3 and Pb(Zr,Ti)O 3 exhibit the change of switching mechanisms as the field increases. At high electric field, they both follow homogeneous switching mechanism without the nucleation of domains. At weak electric fields, the NLS model effectively described the switching behavior of both PbTiO 3 and Pb(Zr,Ti)O 3 , although the atomistic details of their respective switching mechanisms diverge. We demonstrate that, for PbTiO 3 , the switching mechanism at weak fields involves the collective behavior near nuclei such as the formation of vortices, which is characterized by the hypertoroidal moment. We also report the substantial in-plane dipolar pattern of Pb(Zr,Ti)O 3 at low fields, independent of switching. This work contributes to a comprehensive understanding of ferroelectric switching and, thus, results in better prediction of designing new nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Ferroelectric materials play a pivotal role in various industrial and scientific applications due to their ability to exhibit spontaneous electric polarization above a critical temperature. The application of a sufficiently high external electric field can induce the switching of the spontaneous polarization, with the specific mechanism varying across different materials. Understanding the intrinsic switching mechanism is paramount for regulating polarization domains, thereby unlocking potential applications in nanoelectronic devices. Different types of switching mechanisms have been experimentally reported and various models have been developed, among them the nucleation-limited-switching (NLS) model, which is distinguished by nucleation and limited propagation. We investigate the intrinsic polarization switching mechanisms in PbTiO 3 and Pb(Zr,Ti)O 3 using molecular dynamics simulations. We found that both PbTiO 3 and Pb(Zr,Ti)O 3 exhibit the change of switching mechanisms as the field increases. At high electric field, they both follow homogeneous switching mechanism without the nucleation of domains. At weak electric fields, the NLS model effectively described the switching behavior of both PbTiO 3 and Pb(Zr,Ti)O 3 , although the atomistic details of their respective switching mechanisms diverge. We demonstrate that, for PbTiO 3 , the switching mechanism at weak fields involves the collective behavior near nuclei such as the formation of vortices, which is characterized by the hypertoroidal moment. We also report the substantial in-plane dipolar pattern of Pb(Zr,Ti)O 3 at low fields, independent of switching. This work contributes to a comprehensive understanding of ferroelectric switching and, thus, results in better prediction of designing new nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Hexagonal LuFeO3 is known as an improper multiferroic material because of its ferroelectric structural distortion, measured by the Γ 2 − polar mode, and is driven by a trimerization structural distortion represented by the K3 non-polar mode [Fennie and Rabe, Phys. Rev. B 72, 100103(R) (2005)]. The K3 mode is also the primary structural origin of net weak ferromagnetism, associated with the ferromagnetic coupling between the in-plane geometrically frustrated spins. Here, we study the magnetoelectric coupling in LuFeO3 using first-principles calculations and applied external electric fields. We find that the weak ferromagnetism responds to the electric field polarization through the K3– Γ 2 − coupling, which is an intrinsic characteristic of improper multiferroics. Interestingly, the magnetoelectric coupling exhibits strong asymmetry under positive and negative electric fields. This nonlinearity is due to the competition between the K3 and the Γ 2 − modes according to Landau's theory and is related to asymmetrical interatomic interactions at the atomic level. [ABSTRACT FROM AUTHOR]

We present a new methodology to calculate the strong light-matter coupling between photonic modes in microcavities and large molecular aggregates that consist of hundreds of molecular fragments. To this end, we combine our fragment molecular orbital long-range corrected time-dependent density functional tight-binding methodology with a generalized Tavis–Cummings Hamiltonian. We employ an excitonic Hamiltonian, which is built from a quasi-diabatic basis that is constructed from locally excited and charge-transfer states of all molecular fragments. To calculate polaritonic states, we extend our quasi-diabatic basis to include photonic states of a microcavity and derive and implement the couplings between the locally excited states and the cavity states and built a Tavis–Cummings Hamiltonian that incorporates the intermolecular excitonic couplings. Subsequently, we demonstrate the capability of our methodology by simulating the influence of the electric field polarization on the polaritonic spectra for a tetracene aggregate of 125 monomers. Furthermore, we investigate the dependence of the splitting of the upper and lower polaritonic branches on the system size by comparing the spectra of five different tetracene clusters. In addition, we investigate the polariton dispersion of a large tetracene aggregate for electric field polarizations in the x, y, and z directions. Our new methodology can facilitate the future study of exciton dynamics in complex molecular systems, which consist of up to hundreds of molecules that are influenced by strong light–matter coupling to microcavities. [ABSTRACT FROM AUTHOR]

Optical trapping is an effective tool for manipulating micrometer-sized particles, although its application to nanometer-sized particles remains difficult. The field of optical trapping has advanced significantly, incorporating more advanced techniques such as plasmonic structures. However, single-molecule trapping remains a challenge. To achieve a deeper understanding of optical forces acting on molecular systems, a first-principles approach to analyze the optical force on molecules interacting with a plasmonic field is crucial. In our study, the optical force and torque induced by the near-field excitation of C3H6 were investigated using real-time time-dependent density functional theory calculations on real-space grids. The near field from the scanning tunneling probe was adopted as the excitation source for the molecule. The optical force was calculated using the polarization charges induced in the molecule based on Lorentz force. While the optical force and torque calculated as functions of the light energy were in moderate agreement with the oscillator strengths obtained from the far-field excitation of C3H6, a closer correspondence was achieved with the power spectrum of the induced dipole moment using near-field excitation. Time-domain analysis of the optical force suggests that the simultaneous excitation of multiple excited states generally weakens the force because of mismatches between the directions of the induced polarization and the electric field. This study revealed a subtle damping mechanism for the optical force arising from intrinsic electronic states and the influence of beating. [ABSTRACT FROM AUTHOR]

PN junctions play important roles in semiconductor devices. Flexoelectricity, an electromechanical coupling between strain gradient and electric polarization, has non-negligible contributions in nano-devices. The thermoflexoelectric effect is a phenomenon in which temperature gradients generate inhomogeneous strains and further induce flexoelectric polarizations. Therefore, temperature gradients can affect carrier transport in PN junctions through the thermoflexoelectric effect. In this paper, a one-dimensional model of the PN junction under a uniform temperature change is established. Exact solutions for the electromechanical fields in the PN junction are obtained for the first time. The effects of the temperature gradient, doping level, and flexoelectric coefficient on the electromechanical behaviors of the PN junction are numerically analyzed. The results indicate that carrier concentrations in the p and n regions are sensitive to temperature gradients because of the screening effect of the mobile charge on the flexoelectric polarization induced by the temperature gradient. Meanwhile, the flexoelectric field and the initial built-in electric field in the depletion region jointly determine the magnitude of the potential barrier, and thus, the temperature-gradient-induced flexoelectric field can tune the switching characteristics of the PN junction. This study provides a theoretical basis for the tuning of the electromechanical behavior of the PN junction by thermally induced flexoelectric fields. [ABSTRACT FROM AUTHOR]

Some spinel chromium oxides with the chemical formula ACr2O4 exhibit magnetic-induced multiferroicity due to the special spiral spin order. However, because of the relatively low temperature of the ordered spiral phase, this kind of multiferroicity generally displays a limited coexistence of magnetic and ferroelectric orders in a narrow temperature range. The Jahn–Teller (JT) effect, serving as a crucial link between charge and orbit degrees of freedom, can facilitate efficient modulation of multiferroic properties. In this work, Ni1−xCuxCr2O4 (0 ≤ x ≤ 0.2) series are synthesized by occupying the same Wyckoff site with two kinds of JT ions. The microstructure and JT distortion can be distinctly influenced by varying the doping level of Cu2+ ions. Particularly, Ni0.85Cu0.15Cr2O4 (x = 0.15) presents the pronounced JT distortion, accompanied by observation of dielectric anomaly at ∼78 K, resulting from spin–orbit coupling. This implies that the JT effect can significantly promote the contribution of spin–orbit coupling in magnetoelectric correlation. Moreover, the magnetodielectric effect induced by intrinsic magnetoelectric coupling is confirmed in Ni0.85Cu0.15Cr2O4 over a wide temperature range of 10–200 K, which is much higher than the Néel temperature of ∼85 K. It indicates that spin–orbit coupling based on the JT effect could overcome the constraint of magnetic order to achieve effective control on electric polarization performance under an applied magnetic field, thereby showing broad application prospects. [ABSTRACT FROM AUTHOR]

There is no consensus among researchers regarding how phase transitions occur in antiferroelectric (AFE) epitaxial heterostructures, in particular, in heterostructures based on model AFE lead zirconate. The questions about the number of phase transitions in such films and by what mechanism they occur remain controversial. This paper presents a look at the phase transition scenario in two types of epitaxial heterostructures: PbZrO 3 /Ba[La–Sn]O 3 /MgO (001) thin films with thicknesses from 25 to 1000 nm and PbZrO 3 /SrRuO 3 /SrTiO 3 (001) thin film 100 nm thick using the diffuse x-ray scattering in the grazing incidence setup. We register the characteristic butterfly-shaped diffuse scattering (DS) intensity distribution in the H K pseudocubic planes, which corresponds to the anisotropic ferroelectric soft mode. No incommensurate soft mode was observed in the cuts of reciprocal space parallel to the film surface by diffuse scattering. We reproduce the shape of DS distribution at different temperatures by the model based on the dielectric stiffness and the electric polarization correlation tensor in the cubic approximation. Such modeling allows not only to characterize the DS parameters from the challengingly low signal-to-background data set, but also to extract experimentally the sensitivity of the materials with respect to inhomogeneous polarization. While the observed temperature evolution of DS is consistent with the dielectric measurements, the correlation between the DS and the phase transition sequence observed by superstructure reflections is yet to be understood better. [ABSTRACT FROM AUTHOR]

We have fabricated the ZnFe2O4/ZnO (ZFO/ZnO) heterostructure on a silicon substrate by pulsed laser deposition technique and studied the magnetization switching by the electric field in the ZFO/ZnO heterostructure using an indigenously developed optical cantilever beam magnetometer setup. The magnetization (M) vs electric field (E) curve reveals that the magnetization of the ZFO film has been switched by an electric field applied along the thickness of the ZnO film. The saturation magnetization is found to be 28.77 MA/m from the M–E curve. The emergence of electric field-driven magnetization switching in the ZFO/ZnO heterostructure is attributed to the strain-mediated magnetoelectric coupling between the electric polarization of the ZnO film and the magnetization of the ZFO film as evidenced by the butterfly-type hysteresis behavior of magnetization with the applied electric field. However, the realization of electric field-controlled magnetization switching in the ZFO/ZnO heterostructure is regarded as a potential aspect for the fabrication of energy-efficient spintronic devices such as magnetoelectric random access memory cells, highly sensitive magnetic field sensors, magneto-logic devices, and neuromorphic devices. [ABSTRACT FROM AUTHOR]

Element substitution of BaTiO 3 -based compounds has been demonstrated as a powerful way for designing novel electronic materials (such as polar metals and multiferroics). To trigger magnetism into ferroelectric BaTiO 3 , general substituted elements are magnetic transition metals (such as Mn, Fe, and Co). The doping effect of rare-earth elements (such as Dy) in BaTiO 3 -based compounds was barely investigated. Here, we report the coexistence of magnetism and electric polarization in epitaxial Dy 0.5 Ba 0.5 TiO 3 films. The single-crystalline films were synthesized by high-pressure magnetron sputtering. The crystal and electronic structures were characterized by high-resolution x-ray diffraction, x-ray photoemission spectroscopy, and resonant soft x-ray absorption spectroscopy. Room-temperature electric polarization was demonstrated by optical second-harmonic generation. Temperature-dependent magnetic hysteresis loops were measured to reveal the revolution of magnetism on temperature. Surprisingly, it is uncovered that the Curie temperature of electric-polarized Dy 0.5 Ba 0.5 TiO 3 films is around 100 K, far above the critical temperature of non-polarized DyTiO 3 (near 60 K). Our work provides another view to understand the magnetoelectric materials. [ABSTRACT FROM AUTHOR]

Dynamic responses of copper titanates to alternating electric fields with different strengths are characterized in terms of dielectric spectrums. This work extends the introduction of quasipolaron surface polarization (QSP). A collective of quasipolarons pinned at grain surfaces is involved in the electric polarization, which is confirmed by the quadratic polarization–permittivity relation. Because electric polarization is a macroscopic quantum effect, the QSP is described in terms of the density of states (DOS). As a sign of reverse ferroelectricity, dielectric hysteresis loops of reverse-S shape reveal that the characteristic remnant polarization is proportional to the DOS ratio of quasipolaron surface excited to ground states. Although the DOS of the surface ground state is dependent on the mole ratio of quasipolaron quantity, both the DOS and the energy levels of surface excited states show the intrinsic angular-frequency dependence in a power function manner. [ABSTRACT FROM AUTHOR]

Ferroelectrics and multiferroics have added flexibility in device design as they can couple with either electric or magnetic polarization. Here, we report a simple approach to observe ferroelectric and multiferroic behavior in BFO embedded Ti 3 C 2 T x MXene free standing film. Structural, morphological, optical and domain analyses were done using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy, and Piezoresponse Force Microscopy (PFM) respectively. The hysteresis polarization curves obtained at various frequencies, both with and without a static magnetic field, provide confirmation of the frequency-dependent ferroelectric behavior within BFO embedded Ti 3 C 2 T x MXene free standing film. Magneto-electric couplings have demonstrated the film's ability to manipulate electric polarization using a magnetic field. Recently, researchers have unveiled ferroelectric properties in Ti 3 C 2 T x MXene triggered through heat treatment because of oxidation. To investigate this phenomenon, we applied heat treatment to our film which resulted in an amplified polarization value and notably improved results. The fabricated composite film was used in tri-layered device consisting of heated BFO-embedded Ti 3 C 2 T x MXene as middle layer that showed excellent data storage capability controlled by ferroelectricity of the middle layer itself. The simultaneous presence of ferroelectric and multiferroic coupling highlights the promising application of MXene-assisted films in data storage applications. [ABSTRACT FROM AUTHOR]

In laser safety eyewear, due to the lack of complete blocking of ultraviolet and infrared rays, we proposed a structure based on one-dimensional multilayer composed of several layers of silicon dioxide and zirconium dioxide materials alternately behind polycarbonate lens. It is find out that the acceptance angle range to the photonic crystal is 0 to 39°. This incident angle range corresponds to the band gap of the photonic crystal. In the transverse electric polarization, with increasing incident angle, the width of the gap rises, while in the transverse magnetic polarization decreases. Our results show that in the transverse electric mode, the optical density gradually increases with increasing angle while it decreases in the transverse magnetic one. The higher optical density, the higher eye protection at specified wavelength. If the incident wavelength is placed in the band gap region, the field intensity gradually decays. Therefore, the proposed structure for laser safety eyewear can provide the maximum reflection on the surface of the lens. Our supposed structure for safety eyewear can be used in infrared lasers. [ABSTRACT FROM AUTHOR]

Electric polarization typically originates from non-centrosymmetric charge distributions in compounds. In elemental crystalline materials, chemical bonds between atoms of the same element favor symmetrically distributed electron charges and centrosymmetric structures, making elemental ferroelectrics rare. Compared to atoms, elemental clusters are intrinsically less symmetric and can have various preferred orientations when they are assembled to form crystals. Consequently, the assembly of clusters with different orientations tends to break the inversion symmetry. By exploiting this concept, we show that sliding ferroelectricity naturally emerges in trilayer quasi-hexagonal phase (qHP) C60, a cluster-assembled carbon allotrope recently synthesized. Compared to many metallic or semi-metallic elemental ferroelectrics, trilayer qHP C60's have sizable band gaps and several ferroelectric structures, which are distinguishable by measuring their second-harmonic generation (SHG) responses. Some of these phases show both switchable out-of-plane and in-plane polarizations on the order of 0.2 pC/m. The out-of-plane and in-plane polarizations can be switched independently and enable an easy-to-implement construction of Van der Waals homostructures with ferroelectrically switchable chirality. [ABSTRACT FROM AUTHOR]

Ferroelectrics are considered to be promising candidates for highly energy‐efficient electronic devices in future information technologies owing to their nonvolatile and low‐energy operation of spontaneous electric polarization. Driven by the pervasive and growing demands for miniaturization and energy efficiency in nanoelectronics, further reductions in the operating voltage of ferroelectric‐based devices are dispensable and thus have received immense attentions. Recent remarkable advances in atomic‐scale synthesis, cutting‐edge characterizations, and multiscale theoretical calculations of ferroelectrics have gained unprecedented insights into the manipulation of emergent functionalities in multiple length scales, which helps the discovery of nontrivial polar structures and designs of device architectures toward the promise of ultralow‐power consumption. Here, state‐of‐the‐art strategies for reducing operating voltage in ferroelectric materials and devices are reviewed. This article starts with a brief introduction and major achievements in ferroelectrics, and expounds on the techniques to probe the polarization‐switching process. Moreover, this article focuses predominantly on recent advancements in achieving low operating voltages through various prevalent strategies such as thickness scaling, defect engineering, chemical doping, surface and interfacial design, strain engineering. Finally, perspectives with scientific and technical challenges are discussed, aiming to facilitate the energy‐efficient applications of ferroelectric materials and devices in future information technologies. [ABSTRACT FROM AUTHOR]

To meet the needs for higher energy efficiency and a wide operating temperature range of electric vehicles, the low‐loss MnZn ferrites in a wide temperature range have been developed by optimizing the Fe content and the oxygen partial pressure (PO2) during the sintering process in this work. For the optimal sample, power loss at 300 kHz/100mT is 204 kW/m3 at 25°C and remains below 290 kW/m3 in the wide temperature range from ‐10 to 120°C. The loss separation method was employed to clarify the effects of the Fe content and PO2 on power loss. The equivalent circuit model has been employed to fit the complex impedance and it is found that the increase of PO2 enhances both the grain resistance Rg and the grain boundary resistance Rgb. The enhancement of Rgb is mainly responsible for the reduction of eddy current loss and consequently power loss. Dielectric permittivity is as large as about 15000 in this series of samples due to the electric polarization at the rich grain boundaries. Dielectric loss is very low between ‐50 and 150°C and has little contribution to the energy loss. [ABSTRACT FROM AUTHOR]

Spin-polarized edge states in two-dimensional materials hold promise for spintronics and quantum computing applications. Constructing stable edge states by tailoring two-dimensional semiconductor materials with bulk-boundary correspondence is a feasible approach. Recently layered NiI2 is suggested as a two-dimensional type-II multiferroic semiconductor with intrinsic spiral spin ordering and chirality-induced electric polarization. However, the one-dimensional spin-polarized edge states of multiferroic materials down to monolayer limit has not yet been studied. We report here that monolayer NiI2 was successfully synthesized on Au(111) by molecular beam epitaxy. Spin-polarized scanning tunneling microscopy/spectroscopy experiments visualize orientation-selective spin-polarized edge states in monolayer NiI2 islands. By performing first-principles calculations, we further confirm that spin-polarized edge states are selectively aligning along the Ni-terminated edges rather than the I-terminated edges. Our result will provide the opportunity to tune edge states by selected orientation and to develop spintronic devices in two-dimensional magnetic semiconductors. Spin-polarized edge states in two-dimensional materials hold promise for spintronics and quantum computing applications. Here, the authors reveal the orientation-selective spin-polarized edge states along the Ni-terminated edges in monolayer NiI2 islands. [ABSTRACT FROM AUTHOR]

Extending ferroelectric materials to two-dimensional limit provides versatile applications for the development of next-generation nonvolatile devices. Conventional ferroelectricity requires materials consisting of at least two constituent elements associated with polar crystalline structures. Monolayer graphene as an elementary two-dimensional material unlikely exhibits ferroelectric order due to its highly centrosymmetric hexagonal lattices. Here, we report the observations of electronic ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattice at the graphene/h-BN interface, in which the electric polarization stems from electron-hole dipoles. The polarization switching is probed through the measurements of itinerant Hall carrier density up to room temperature, manifesting as standard polarization-electric field hysteresis loops. We find ferroelectricity in graphene moiré systems exhibits generally similar characteristics in monolayer, bilayer, and trilayer graphene, which indicates layer polarization is not essential to observe the ferroelectricity. Furthermore, we demonstrate the applications of this ferroelectric moiré structures in multi-state nonvolatile data storage with high retention and the emulation of versatile synaptic behaviors. Our work not only provides insights into the fundamental understanding of ferroelectricity, but also demonstrates the potential of graphene for high-speed and multi-state nonvolatile memory applications. Monolayer graphene, with its highly centrosymmetric hexagonal lattice, is typically not considered ferroelectric. Here, the authors observe ferroelectricity in monolayer graphene by introducing asymmetric moiré superlattices, where polarization arises from electron-hole dipoles. [ABSTRACT FROM AUTHOR]

Displacement‐type ferroelectrics usually exclude magnetic d‐electron contribution. Applying a magnetic field thus can little change the electric polarization. Herein, a magnetic ionic driven displacement‐type perovskite ferroelectric CaFe3Ti4O12 is reported. In this compound, magnetic Fe2+ ions contribute to both ferroelectric and antiferromagnetic orders respectively at TC ≈107 and TN ≈ 3.1 K, resulting in coupled electric and magnetic domains. A moderate magnetic field can induce a metamagnetic transition toward ferromagnetic correlations. External magnetic fields can thus readily tune the magnetic and the joint ferroelectric domains, giving rise to exceptional magnetic‐field controllable displacement‐type polarization with a large magnetoelectric (ME) coupling coefficient. This study opens up a new avenue to find unprecedented ME effects in displacement‐type ferroelectrics for numerous applications. [ABSTRACT FROM AUTHOR]

The counterintuitive negative longitudinal piezoelectric effect (NLPE) occurs in those piezoelectric compounds whose electric polarizations are enhanced under the compression stress(strain) applied along the polar axis. Especially, piezoelectric materials with sizable NLPE responses suitable for electromechanical applications are highly desirable. Here, based on comprehensive first‐principles calculations and theoretical modeling, NLPE and substantial negative piezoelectric responses are demonstrated to be prevalently attained in various synthetic heteroanionic 2D van der Waals (vdW) layered materials with intrinsic out‐of‐plane polarizations. Depending on their interlayer spacing percentages and interlayer electronic coupling magnitudes, NLPE in most polar layered materials arise either from the domination of negative "internal‐strain" over positive "clamped‐ion" contributions, or negative "clamped‐ion" over "internal‐strain" contributions. As an exception, Sb2TeSe2 is predicted to have both negative "clamped‐ion" and "internal‐strain" terms in considerable magnitudes, contributing cooperatively to overall piezoelectric response and yielding a giant negative longitudinal piezoelectric coefficient d33 up to –32.666 pC N−1. Furthermore, piezoresponse force microscopy (PFM) measurements performed on Sb2TeSe2 crystal verify its non‐centrosymmetric structural character and sizable piezoelectric responses. Combining the comprehensive simulations and experimental characterizations, this work deepens the understanding regarding the unusual NLPE, and demonstrates a practical route for screening the polar vdW layered materials with substantial NLPE. [ABSTRACT FROM AUTHOR]

(1- x) BaTiO 3 – x Bi(Mg 0.25 Zn 0.25 Ti 0.5)O 3 (x = 0.00, 0.06, 0.12, 0.20,molar ratio) ceramics were prepared by solid sintering method. The effects of Bi(Mg 0.25 Zn 0.25 Ti 0.5)O 3 (BMZT) doping on microstructure, dielectric, ferroelectric and energy storage properties of BaTiO 3 (BTO) were studied. With BMZT addition, the sintering temperature gradually decreases, the grain size reaches a minimum at x = 0.12 and the phase structure changes from tetragonal to cubic. And dielectric properties changed from temperature-dependent to temperature-insensitive. Additionally, higher cubic phase content induced slim polarization and electric field (P-E) loop and low remnant polarization (P r). Therefore, 0.88 BaTiO 3 - 0.12 Bi(Mg 0.25 Zn 0.25 Ti 0.5)O 3 ceramics achieved recoverable energy storage density (W rec) of 702.7 mJ/cm3 and high energy efficiency of 87.3 % under electric field of 93 kV/cm. It exhibited optimum properties, including a minimum grain size (0.620 μm), superior dielectric properties (ε r = 1811.3, tanδ = 0.0552 at 1150 °C), a high maximum polarization strength (14.3 μC/cm2), and the maximum dielectric breakdown strength (93 kV/cm), as identified in the present study. It simultaneously maintains high energy storage density and efficiency over a wide electric field range and large temperature range (room temperature - 90 °C). Thus (1- x) BaTiO 3 – x Bi(Mg 0.25 Zn 0.25 Ti 0.5)O 3 ceramics are a promising material for energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Flexoelectricity incorporating electric polarization and strain gradients exists in all dielectrics. In the present work, the function of Hamilton's principle of the elastic dielectric materials considering the flexoelectric effect is established and its stationary conditions are also obtained. A bilayer beam composed of elastic and piezoelectric parts is modeled to investigate flexoelectricity under both mechanical and electrical loads. Based on Hamilton's principle, the governing equation and boundary conditions of a piezoelectric/elastic bilayer beam with generalized supporting ends are deduced. Accordingly, the analytical solutions to the horizontal displacements are derived. It is found that the flexoelectric effects depend on the size heavily, which is dominant for the structures at nanoscale but had hardly influence on the larger ones. Moreover, the piezoelectric/elastic bilayer beam behaves much better on controlling of the bending flexibility by adjusting the thickness ratio of the two parts. It's hopeful to provide guidance for designing and optimizing nanoscale electronic devices. [ABSTRACT FROM AUTHOR]

Recently, the noncollinear magnetic structure with varying Co/Zn ratios was reported in the W-type hexaferrites using neutron powder diffraction. It is believed that these noncollinear spin orderings may stimulate magnetoelectric (ME) effect in the W-type hexaferrite. Herein, we present distinct evidence of ME response through systematic investigation on the magnetic and ferroelectric properties in BaCoFe17O27. Magnetization exhibits two different anomalies at TC1 ∼ 350 K and TC2 ∼ 150 K, indicating the formation of long-range longitudinal spin configurations and the spin reorientation transition, respectively. We have found that the low field-driven electric polarization has been observed under the ME poling condition of E ⊥ (H ⊥ c, and c). Spin current mechanism is mainly considered as the physics origin in its ME response, corresponding to the other hexaferrites as reported early. In addition, the weak electric polarization observed with E(⊥c)//H(⊥c) suggests that the p–d hybridization mechanism should also be contributed to the ME response in this compound. Therefore, BaCoFe17O27 presents an intrinsic magnetoelectric effect and provides a thought for people to seek and study the more single-phase ME compounds from the viewpoint of foundational and applications. [ABSTRACT FROM AUTHOR]

The study presents a novel self‐powered ultraviolet (UV) photodetector harnessing both polarization fields and photovoltaic effects, enabling the realization of ultra‐low power, reconfigurable optoelectronic logic gates. The approach is demonstrated on a CuO/BaTiO3 heterojunction photodetector. The behavior of the photodetector is augmented by the poling effect, aligning the internal electric field of the BaTiO3 through the application of a robust external electric field, thereby facilitating the implementation of optoelectronic logic gates. In the unpoled state, the "XOR" and "OR" logic gates operated at voltages of 750 and −500 µV, respectively. However, upon poling up state, the "XOR" logic gate exhibits reduced operation voltage, operating at 500 µV, while the "OR" logic gate implements clarity at −500 µV. In the unpoled state the "AND" logic gate does not operate; however, upon poling in the downward direction, it operated at −500 µV. The achievement demonstrates successful ultra‐low‐power logic operations, utilizing voltages in the hundreds of micron scale, under a 310 nm wavelength and a light intensity of 0.52 mW·cm−2. Furthermore, controllable polarization electric fields in BaTiO3 enable the operation of "AND" logic gate in the unpoled state, presenting a promising avenue for future research in optoelectronic logic gate design. [ABSTRACT FROM AUTHOR]

The field of bioinspired iontronics, bridging electronic devices and ionic systems, has multiple biological applications. Carbon‐based ultracapacitive devices hold promise for controlling bioactive ions via electric double layers due to their high‐surface‐area and biocompatible porous carbon electrodes. However, the interplay between complex bioactive ions and porous carbons remains unclear due to the variety of structures of bioactive ions present in biological systems. Herein, we investigate the adsorption behavior of a series of bioactive ammonium‐based cations with varying alkyl chain lengths in nanoporous carbons. We find that strong physisorption results from the synergistic hydrophobic interaction and electrostatic attraction between porous carbons (with a negative zeta potential) and bioactive cations. Bioactive cations with varying alkyl chain lengths can be irreversibly physically adsorbed and confined within nanoporous carbons resulting in anion enrichment and depletion during electric polarization. This situation, in turn, results in a characteristic memristive behavior in all‐carbon capacitive ionic memristor devices. Our findings highlight the relationship between the resistance state of the memristor and ion adsorption mechanisms in all‐carbon capacitive devices, which hold potential for future transmitter delivery, biointerfacing, and neuromorphic devices. [ABSTRACT FROM AUTHOR]

In this work, an experimental study supported by numerical modeling that demonstrates the possibility of exciting Symmetry Protected‐Bound states In the Continuum (SP‐BICs) in a 1D silicon grating fabricated on a lithium niobate substrate is presented. bBoth transverse electric and magnetic polarization states are investigated, leading to the excitation of four quasi‐ Bound states In the Continuum (quasi‐BIC) resonances, exhibiting distinct behaviors. Under standard illumination conditions (plane of incidence perpendicular to the 1D grating lines), two of these resonances are highly sensitive to illumination conditions, while the other two resonances involving unconventional illumination directions (plane of incidence parallel to the grating lines) are more robust to the angle of incidence, but just as sensitive to external stresses in terms of resonance wavelength and quality factor. Additionally, temperature detection is experimentally demonstrated with a Sensitivity of ST = 0.81∼nm °C−1, a state‐of‐the‐art value achieved due to significant electromagnetic field enhancement inside the lithium niobate substrate at the quasi‐BIC resonance. These findings pave the way for their use in various sensing applications (such as biology, electromagnetic, and temperature sensing), as well as nonlinear applications like second harmonic generation, and electro‐ and acousto‐optic modulation. [ABSTRACT FROM AUTHOR]

The electrical characteristics of the ferroelectric field-effect transistors (FeFETs) are analyzed numerically and presented in this paper. The metal–ferroelectric–insulator–semiconductor field-effect transistor (MFISFET), among the primary structures, is taken into consideration. The nonsaturated hysteresis loop of the ferroelectric material is described by a novel analytical calculation for the relation of polarization against electric field (P–E). The combined impact of the nonuniform concentrations of electric field charge throughout the channel and the nonsaturated polarization of ferroelectric layers are considered to create a more realistic modeling. The proposed research work also provides an in-depth study of the electrical properties of the GAA-based Nanowire FeFET, exploring important variables including transconductance, subthreshold swing, as well as a threshold voltage. The analytical insights derived from the mathematical framework are consistent with the simulated results obtained with the ATLAS 3D simulator. [ABSTRACT FROM AUTHOR]

Developing efficient photo‐piezocatalytic systems to achieve the conversion of renewable energy to chemical energy emerges enormous potential. However, poor catalytic efficiency remains a significant obstacle to future practical applications. Herein, a series of unique Au@BaTiO3 (Au@BT) yolk‐shell nanostructure photo‐piezocatalyst is constructed with single Au nanoparticle (Au NP) embedded in different positions within ferroelectric BaTiO3 hollow nanosphere (BT‐HNS). This special structure showcases excellent mechanical force sensitivity and provides ample plasmon‐induced interfacial charge‐transfer pathways. In addition, the powerful piezoelectric polarization electric field induced by the enhanced ferroelectric polarization electric field via corona poling treatment in BT‐HNS further promotes charge separation, CO2 adsorption and key intermediate conversion. Notably, BT with single Au NP encapsulated into hollow nanosphere shell with reinforced polarization (Au@BT‐1‐P) shows synergistically improved photo‐piezocatalytic CO2 reduction activity for producing CO with a high production rate of 31.29 µmol g−1 h−1 under visible light irradiation and ultrasonic vibration. This work highlights a generic tactic for optimized design of high‐performance and multifunctional nanostructured photo‐piezocatalyst. Meanwhile, these yolk‐in‐shell nanostructures with single Au nanoparticle as an ideal model may hold great promise to inspire in‐depth exploration of carrier dynamics and mechanistic understanding of the catalytic reaction. [ABSTRACT FROM AUTHOR]

Two rheological Burgers–Faraday models and rheological dynamical systems were created by using two new rheological models: Kelvin–Voigt–Faraday fractional-type model and Maxwell–Faraday fractional-type model. The Burgers–Faraday models described in the paper are new models that examine the dynamical behavior of materials with coupled fields: mechanical stress and strain and the electric field of polarization through the Faraday element. The analysis of the constitutive relation of the fractional order for Burgers–Faraday models is given. Two Burgers–Faraday fractional-type dynamical systems were created under certain approximations. Both rheological Burgers-Faraday dynamic systems have two internal degrees of freedom, which are introduced into the system by each standard light Burgers-Faraday bonding element. It is shown that the sequence of bonding elements in the structure of the standard light Burgers-Faraday bonding element changes the dynamic properties of the rheological dynamic system, so that in one case the system behaves as a fractional-type oscillator, while in the other case, it exhibits a creeping or pulsating behavior under the influence of an external periodic force. These models of rheological dynamic systems can be used to model new natural and synthetic biomaterials that possess both viscoelastic/viscoplastic and piezoelectric properties and have dynamical properties of stress relaxation. [ABSTRACT FROM AUTHOR]

Magnons are viewed as local deviations from the ordered state. Usually, the spin magnetic moment of magnons is considered. In a 3D‐confined structure of a magnetic insulator with magnetodipolar mode (MDM) oscillations, an orbital angular momentum (OAM) as well as a spin angular momentum (SAM) can be observed along a static magnetic field. In such a confined structure as quasi‐2D ferrite disk, energy levels of MDM oscillations are quantized. Quantum confinement is characterized by a half‐integer internal OAM, which is also associated with a circulating energy flow. The observation of MDM resonances in the 3D‐confined structure of a magnetic insulator is due to the interaction of two subsystems: ferromagnetic and electric polarization orders. The coupling states of these two concurrent orders, caused by OAMs, are considered as magnetoelectric (ME) states. The near fields of MDM resonators are characterized by simultaneous violation of time reversal and inversion symmetry. This plays a significant role in the problems of strong light‐matter interaction regime and quantum atmosphere. The analysis of SAM and OAM in 3D‐confined magnetic insulators becomes very important for the realization of ME meta‐atomic structures. Current interest lies in considering such artificial systems as subwavelength ME quantum emitters of electromagnetic radiation. [ABSTRACT FROM AUTHOR]

BaTiO 3 /Ca 10 (PO 4) 6 (OH) 2 composite ceramic is an outstanding representative of piezoelectric biomaterials, with excellent biocompatibility and piezoelectric effect, and has potential applications in the field of bone tissue repair. In this work, vat photopolymerization 3D printing technology was used to fabricate triply periodic minimal surface structure BaTiO 3 /Ca 10 (PO 4) 6 (OH) 2 composite ceramic bone tissue scaffolds with different pore sizes and porosity, and their mechanical and electrical properties were studied. First, the ceramic slurry configuration process was optimized to obtain a ceramic slurry with high solid content (45 vol%) and excellent rheological properties. Then the effect of sintering temperature on microstructure, relative density, mechanical properties, and electrical properties is discussed. The results show that when sintering at 1300 °C, the BaTiO 3 /Ca 10 (PO 4) 6 (OH) 2 composite ceramic has the highest relative density (99.18 %), the highest compressive strength (44 MPa), large relative dielectric constant (379–389), and low dielectric loss. The polarization electric field strength of the BaTiO 3 /Ca 10 (PO 4) 6 (OH) 2 composite ceramic was set to 15 kV/cm through the test of the hysteresis loop. Finally, based on multi-physics coupled finite element simulation, the effects of different porosity and different pore sizes on stress distribution and piezoelectric potential were analyzed, and the relationship between them was explored through experiments. The results show that as the porosity increases and the pore size decreases, the mechanical properties of the scaffold decrease significantly, and its compressive strength ranges between 1.67 and 4.26 MPa; as the porosity increases and the pore size increases, the piezoelectric coefficient (d 33 ) of the scaffold showed a decreasing trend, and its d 33 ranged between 2 and 9 pC/N. The mechanical and electrical properties of the scaffold meet the performance requirements of cancellous bone. In summary, this work provides a strategy for the application of customized BaTiO 3 /Ca 10 (PO 4) 6 (OH) 2 composite ceramic scaffolds in new-generation orthopedic implants. [ABSTRACT FROM AUTHOR]

Some physical properties (structural, dielectric and optical) of a complex lead-free ceramic [ Bi 1 ∕ 2 Na 1 ∕ 2 ][ Fe 1 ∕ 2 W 1 ∕ 2 ]O3 have been thoroughly examined in different experimental conditions in this study. It was fabricated via a solid-state reaction method. The crystal structure is monoclinic, according to the detailed analysis of the X-ray diffraction pattern. Also, the functional vibrational bands can be observed in the FT-IR and Raman spectra, which support the creation of the molecular structure. Scanning electron microscope (SEM) images of the sample clearly show the effects of Na + and W 6 + incorporation in morphology, and energy dispersive X-ray spectroscopy (EDX) indicates the existence of all constituents. The non-overlapping small polaron tunneling (NSPT) and correlated barrier hopping (CBH) model conduction mechanisms are examined through Jonscher's power law. The contribution of the grain and grain boundary to the capacitive behavior is shown by Nyquist plots. According to a leakage current analysis, the compound exhibits Ohmic and space charge limited conduction (SCLC) conduction mechanisms. Electric field polarization was used to study the ferroelectric nature. The findings of this study show that the inclusion of Na + and W 6 + is an efficient technique to improve its dielectric and optical characteristics. [ABSTRACT FROM AUTHOR]

This paper investigates the role of coupled E‐ and F‐regions electrodynamics behind the rapid poleward extension of two dark fronts of an electrified medium‐scale traveling ionospheric disturbance (EMSTID). The fronts of EMSTID observed in O(1D) 630.0 nm airglow images extended poleward from the southern edge of the field‐of‐view to the location of the imager at Hanle (32.7°N, 78.9°E; Mlat. ∼ $\mathit{\sim }$ 24.1°N), India, on the geomagnetically quiet (Ap = 3) night of 09 June 2021. The existence of the fronts outside the southern edge of field‐of‐view before and during their extension was apparent from temporal fluctuations in the vertical total electron content. Additionally, favorable direction of thermospheric neutral wind to initiate Perkins instability existed beyond the southern edge of field‐of‐view prior to EMSTID's first appearance in the airglow images. Therefore, the observed EMSTID were likely generated outside the southern edge of field‐of‐view. Interestingly, the expected clockwise rotation of fronts with clockwise rotation of thermospheric neutral wind was not observed, although it was necessary to sustain the positive‐growth of Perkins instability. This indicates the involvement of E‐F coupling to sustain the positive‐growth of EMSTID since the presence of sporadic‐E layers was evident from the signal‐to‐noise ratio amplitude of L1 band and zonal wind profiles over the observation region. The enhanced polarization electric field caused due to E‐F coupling produced larger vertical E × B drift, which helped the EMSTID to sustain positive‐growth during the fronts' extension. Additionally, the enhanced northwestward E × B drift helped to maintain the northwest‐southeast orientation of EMSTID fronts, during the rotation of thermospheric neutral wind. Key Points: Rapid poleward extension of two dark fronts of EMSTID observed in O(1D) 630.0 nm airglow images over Hanle, IndiaSporadic‐E layers over the region was observed from the altitude profiles of zonal wind and signal‐to‐noise ratio amplitude of L1 bandModified electrodynamics due to E‐F coupling was plausible mechanism behind the poleward extension of EMSTID fronts [ABSTRACT FROM AUTHOR]

The effect of residual stress or heat on ferroelectrics used to convert photons into electricity was investigated. The data analysis reveals that when the PET-PZT piezoelectric transducer is UV-irradiated with a 405 nm wavelength, it becomes a photon–heat–stress electric energy converter and capacitator. Our objective was to evaluate the PET-PZT photon–heat–stress electric energy conversion performance and the role of the light's wavelength and intensity. Converting waste energy from energy-intensive processes and systems is crucial to reducing the environmental impact and achieving net-zero emissions. To achieve these, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. [ABSTRACT FROM AUTHOR]

A new type of fully polarimetric retrodirective array (RDA) using a PON-type structure is proposed in this paper. The fully polarimetric property is the result of the proposed phase conjugation circuits, which perform phase conjugation processing on the x, y, and z polarization electric field components of the incident wave when combined with a tri-polarized antenna array. It enables the retrodirective array to receive and retransmit an arbitrary polarized incident wave. The measured results of the monostatic radar cross-section (RCS) show that the −5 dB beam width of the array was greater than 95° at 9.6 GHz for different polarized incident waves. Furthermore, the proposed RDA has better retrodirectivity performance on arbitrary polarized incident waves when using a wide-beam antenna, and if we further incorporate modulation and demodulation into the circuits, it has the potential to be applied to the wireless communications field. [ABSTRACT FROM AUTHOR]

A series of novel lead-free tungsten bronze-structured Ba4(Dy2-xBix)Fe2Nb8O30 (x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25) were formulated by the traditional high-temperature solid-state method using ball milling for 30 hrs and calcined at 1115°C. The structural property was investigated using X-ray diffraction and Fourier transform infrared spectroscopy. The tetragonal structure with the P4bm space group was confirmed from Rietveld analysis. The scanning electron micrograph shows a uniform distribution of different-shaped grains with less porosity. The UV-vis analysis shows that the materials have band gaps in the range of 2.45–2.51 eV which makes them useful for photocatalytic applications. From photoluminescence analysis, it is confirmed that the samples can be used as violate-/blue light-emitting diodes. The impedance of the materials falls off with the rise in temperature showing their negative temperature coefficient behaviour. The variation of polarization with an electric field confirms the ferroelectric nature of the samples. [ABSTRACT FROM AUTHOR]

Atomically thin materials with coupled magnetic and electric polarization are critical for developing energy-efficient and high-density spintronic devices, yet they remain scarce due to often conflicting requirements of stabilizing both magnetic and electric orders. The recent discovery of the magnetoelectric effect in the 2D stripy antiferromagnet CrOCl highlights this semiconductor as a promising platform to explore electric field effects on magnetoresistance. In this study, we systematically investigate the magnetoresistance in tunneling junctions of bilayer and monolayer CrOCl. We observe that the transition from antiferromagnetic to ferrimagnetic phases in both cases induces a positive magnetoresistance at low bias voltages, which reverses to a negative value at higher bias voltages. This polarity reversal is attributed to the additional electric dipoles present in the antiferromagnetic state, as supported by our theoretical calculations. These findings suggest a pathway for the electric control of spintronic devices and underscore the potential of 2D magnets like CrOCl in advancing energy-efficient spintronic applications. [ABSTRACT FROM AUTHOR]

Thermoacoustic imaging (TAI) contrast comes from different electrical properties (EPs) of microwave absorption. However, the relationship between the permittivity distribution and the electric field polarization limits the application of TAI in some extent. Here, we present a polarimetric thermoacoustic imaging (pTAI) system based on a rotary waveguide. By optimizing a rotary waveguide (insertion loss < 0.2dB, return loss > 15dB at 3GHz), the excitation wave emitted from a horn antenna can rotate freely in the direction of polarization. The multi-polarization pulsed microwave signal is used to evoke the thermoacoustic signals (TAS) of samples in different polarimetric directions. The simulation for pTAI with a multi-directional sample is first obtained. Then, we rotated the rotary waveguide at 10∘/s and experimentally demonstrated the performance of pTAI by imaging three randomly placed soy sauce tubes and ex vivo beef. This study suggests that pTAI has potential for dielectric properties “diffusion” mapping, for example, provides conductivity tensor mapping of brain and muscle. [ABSTRACT FROM AUTHOR]

The flexoelectric effect is an electro-mechanical coupling between strain gradients and the electric polarization, and it is especially significant for nanoscale structures. Since the strain gradient scales up with the decrease in the sample's feature size, the flexoelectric effect is size dependent. Due to the stress concentration, large strain gradients can be found at the crack tip and result in significant flexoelectric effect. However, for micro- or nanoscale cracks, it is still not clear how the flexoelectric effect changes with the size of cracks. In practice, the crack tip has finite radius. So, in addition to the crack length, the crack tip radius is also one of the geometric parameters describing the size of nanocracks. In this work, using our collocation mixed finite element method (CMFEM), we study the size dependence of flexoelectricity around nanocracks through these two parameters. Numerical simulation results indicate that stronger flexoelectric field can be formed around the tip of cracks with either larger crack length or smaller tip radius. We also analyze the interplay of the crack length and the tip radius and show how the crack tip flexoelectric field varies when both of these two parameters are changing. [ABSTRACT FROM AUTHOR]

Manipulating the electronic structure and geometric coordination environment of single metal atoms has been considered as promising approach for enhancing dipole polarization and enriching electromagnetic attenuation mechanisms. However, achieving precise control of the dielectric polarization response at atomic scale remains a huge challenge. Herein, a metal‐acetate coordination complexes‐assisted strategy is proposed to prepare spatially isolated cobalt (Co) atoms embedded in accordion‐like nitrogen‐doped carbon (NC) matrix. The interactions between metal atoms and NC matrix are carefully tailored through the successive evolution of dispersion states of Co species, ranging from individual atoms to atomic clusters to nanoparticles. Density functional theory reveals that the orbital hybridization between the d electrons of embedded Co atoms and p electrons of coordinated N atoms induces the electron redistribution at N sites, enabling enhanced electric dipole polarization and robust room temperature magnetism (a saturation magnetization of 0.108 emu g−1 at 300 K). Consequently, Co‐SAs@NC exhibits optimal electromagnetic wave absorption properties with a minimum reflection loss of ‐54.4 dB and an effective absorption bandwidth of 8.4 GHz. This work demonstrates an efficient strategy for modulating electromagnetic response at atomic level and provides a novel insight into the d/p electrons orbital hybridization between single metal atoms and NC species. [ABSTRACT FROM AUTHOR]

Polarization grading in AlGaN/GaN‐based high‐electron‐mobility transistors (HEMTs) is a promising device design option that can improve linearity, speed, power, and noise performance for use in millimeter‐wave applications. This work investigates the potential of compositionally graded HEMT heterostructures to enhance device breakdown through lateral electric field engineering while maintaining a high device cutoff frequency (fT) due to reduced longitudinal optical (LO) phonon scattering. The impact of polarization grading on electric field profile is compared with conventional gate‐integrated mini‐field plates (mini‐FPs). It is also observed that polarization grading can augment the efficacy of gate‐connected FPs, further enhancing performance. Using physics‐based 2D device simulations, it is demonstrated that polarization engineering via polarization grading enhances breakdown (VBD) while preserving high fT, resulting in a Johnson's figure of merit (JFOM = fT × VBD), that is, ≈2.4× that of a conventional abrupt‐junction HEMT. This improvement represents a significant advancement over the ≈1.25× to ≈2× increase achieved with the use of mini‐FPs alone in HEMTs. [ABSTRACT FROM AUTHOR]

Zinc metal stands out as a promising anode material due to its exceptional theoretical capacity, impressive energy density, and low redox potential. However, challenges such as zinc dendrite growth, anode corrosion, and side reactions in aqueous electrolytes significantly impede the practical application of zinc metal anodes. Herein, 3‐(1‐pyridinio)‐1‐propanesulfonate (PPS) is introduced as a zwitterionic additive to achieve long‐term and highly reversible Zn plating/stripping. Due to the orientation polarization with the force of electric field, PPS additive with π–π conjugated pyridinio cations and strong coordination ability of sulfonate anion tends to generate a dynamic adsorption layer and build a unique water–poor interface. PPS with steric hindrance effect and strong coordination ability can attract solvated Zn2+, thereby promoting the desolvation process. Moreover, by providing a large number of nucleation sites and inducing zinc ion flow, the preferred orientation of the (002) crystal plane can be achieved. Therefore, the interfacial electrochemical reduction kinetics is regulated and uniform zinc deposition is ensured. Owing to these advantages, the Zn//Zn symmetrical cell with PPS additive exhibits remarkable cycling stability exceeding 2340 h (1 mA cm−2 and 1 mA h cm−2). The Zn//V2O5 full cell also delivers stable cycling for up to 6000 cycles. [ABSTRACT FROM AUTHOR]

We report an unexplored type-II multiferroic order in NiMn 2 O 4 , exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼ 100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼ 535 μ C/m 2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼ 21 %) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼ 100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound. [ABSTRACT FROM AUTHOR]

We report an unexplored type-II multiferroic order in NiMn 2 O 4 , exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼ 100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼ 535 μ C/m 2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼ 21 %) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼ 100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound. [ABSTRACT FROM AUTHOR]

Dual electric field and defect engineering induced multi-channel electron transfer promoted the hydrogen production of CZMOZIS heterojunction. [Display omitted] • A high efficient CZMOZIS heterojunction was synthesized by hydrothermal method. • The H 2 evolution rate of CZMOZIS was 9.7 times than that of ZIS. • The enhanced IEF of the CZMOZIS composites provided a strong driving force for charge transfer. • Dual electric field and defect engineering promoted the hydrogen production of CZMOZIS heterojunction. Serious recombination of photogenerated carriers is the bottleneck problem of achieving high-performance photocatalytic reaction. A high efficient Cu2+-doped ZnMoO 4 /ZnIn 2 S 4 (CZMOZIS) heterojunction was synthesized by hydrothermal method. The CZMOZIS heterostructure achieved hydrogen production of 11637.5 µmol g−1 within 5 h, which was 9.7 times higher than that of pure ZnIn 2 S 4. Comprehensive characterization and theoretical calculation demonstrated that the CZMOZIS composites exhibited broad light absorption, an increased specific surface area and an optimized Gibbs free energy. The presence of oxygen vacancies in CZMOZIS composites was confirmed by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy, revealing the formation of defect levels below the conduction band (CB) of ZnMoO 4. Kelvin probe force microscopy (KPFM) and Zeta potential demonstrated that the intrinsic electric field (IEF) of the CZMOZIS heterojunction was enhanced, which may be attributed to the generation of polarization electric field (PEF). The double electric field provided a robust driving force for the photogenerated carrier migration and separation. The electrons in the CB and defect levels of Cu2+-ZnMoO 4 could be coupled with the holes of ZnIn 2 S 4 , thereby forming a multi-channel electron transfer. This work provides a theoretical support for promoting charge transfer to improve photocatalytic performance by dual electric field and defect engineering. [ABSTRACT FROM AUTHOR]

Electro-optical modulation of a terahertz beam by drifting space-charge domains in n-GaN epilayers under pulsed electric field excitation was found and investigated at a temperature of 77 K. The free charge carrier contribution was observed as the attenuation of terahertz (THz) transmission whose value independently on THz beam polarization increased with the electric field, in the presence of drifting space-charge domains, up to 10%. The electro-optical contribution, on the other hand, was sensitive to beam polarization and demonstrated a nonlinear increase in THz transmission up to 50% under the external electric field up to 1.6 kV/cm, while higher field values led to an electrical breakdown of samples operating in the presence of drifting space-charge domain. [ABSTRACT FROM AUTHOR]