The pulse withstand capability is beyond the structural phase diagram and the electronic structure of lead zirconate titanate family, although it is crucial for the safe and reliable operation. In this work, 15,000 engineering ceramic capacitors of ferroelectric, poled, and rhombohedral Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3, are utilized as an example, to perform the positive and high-voltage pulse withstand test, the impedance analysis and the electric polarization characterization. When the density of state is trap-like in the band gap of the electronic structure, the two energy structures of topological defect states in the gap are developed, to clarify the breakdown probability phenomenon in the test, which are in the quantitative agreement with all of the experiments. The structures highlight the macroscopic quantum nature, offering a failure mechanism for the single capacitor and a strategy of improving device yield rate.

This paper presents a bandwidth-enhanced, low-profile dual-polarization (dual-pol) patch antenna array with a height of only 0.03λ₀ for glass-enclosed mobile platforms in 5G-enabled IoT applications at the millimeter-wave band. The bandwidth improvement and low-profile characteristic are achieved through a single-layer radiating patch fed by closely positioned lateral microstrip resonators, forming a multi-resonance structure that expands bandwidth while reducing the overall height by minimizing vertical feeding components. Dual-pol performance is accomplished via common-mode excitation of back-to-back C-shaped quarter-wavelength resonators on one side of the patch for one polarization, and differential-mode excitation of folded line-shaped resonators symmetrically placed on opposite sides for the orthogonal polarization, achieving extended bandwidth and high isolation. Building on this antenna element, a 1×4 dual-pol phased array is implemented for beam steering, fabricated using high-density interconnect (HDI) technology. Measurements reveal an operating bandwidth of 25.56–28.04 GHz (a fractional bandwidth of 9.5%) for x-pol and 24.42–28.49 GHz (15.6%) for y-pol. Beam scanning across ±45° shows a gain degradation of less than 3 dB, with cross-polarization levels remaining below -20 dB within the main lobe at each scan angle. This design is intended for integration within the camera region of a mobile terminal and has been optimized for operation in an under-glass environment. Performance tests conducted with a glass cover confirm the robustness of the design as an effective under-glass antenna for terminal applications.

ABSTRACT Aiming to explore structurally stable and easily fabricable magneto‐optical (MO) platforms for potential refractive‐index‐sensing applications, this work investigates stacking‐number‐dependent low‐field‐enhanced polar magneto‐optical Kerr effect (P‐MOKE) in substrate/AlN buffer/[CoPt(3 nm)/AlN(22 nm)] N /CoPt(3 nm) multilayer structures. With increasing stacking number N , the magnetic hysteresis loops gradually evolved into pronounced step‐like behaviors, indicating the coexistence of two magnetically distinct regions with different coercivity ( H C ) values along the film thickness direction. Correspondingly, low‐field‐enhanced Kerr rotation ( θ K ) hysteresis loops were observed, where the θ K in the low‐field region exceeded that of the saturated state. To clarify the origin of this behavior, inverse MO Fresnel transfer matrix method analysis was performed by separating the multilayer structure into top and bottom CoPt regions with distinct magnetic reversal characteristics. The fitting results revealed that the two regions exhibit different complex Voigt vectors and contribute oppositely to the θ K hysteresis behavior. The observed low‐field‐enhanced P‐MOKE was interpreted as a consequence of the competition between opposite MO polarities and different H C values between these spatially separated magnetic regions along the film thickness direction. In addition, the extracted Voigt vector difference suggests that MO coupling may be influenced by the structural environment and residual‐stress‐related variations. Furthermore, the multilayer structures exhibited appreciable sensitivity to variations in the surrounding dielectric‐environment at 408 nm, indicating potential applicability in MO sensing.

Abstract A macroscopic transport mechanism for superconductivity is lacking. In this work, we performed a complete impeditivity spectrum analysis of a 122-family electron-doped pnictide, i.e. BaFe 2− x Ni x As 2 ( x = 0.065, 0.085, 0.1, 0.12, 0.15, 0.2, and 0.25). Below the critical temperature, the complex impeditivity exhibited in-plane anisotropy, with the AC resistivity as its real part and AC inductive reactivity as its imaginary part. In terms of electron duality, we emphasize the wave nature rather than the particle nature. The vortex waves of paired electrons propagated along the c axis of the single crystals to pass through series-connected nanoslabs in the ab -plane. In each nano-slab, the quantum nanodomains (QNs) of the magnetic flux in the Abrikosov sublattice were surrounded by a conducting region. The nano-slab was identified using the geometric-phase coefficient of a positive integer. Parallel nanodomains were the same in the nano-slabs, and all of them were characterized by the nano-slab coefficient when the conducting region was zero. The complex impeditivity plot revealed conducting heterogeneity between superconducting QNs and the conducting region. When the QN contained a magnetic flux quantum, the superconducting current was amplified, where the quantum number was dependent not only on the crystal axis but also on the dopant. When we predicted the ultimate superconductor with zero impeditivity, the other nanodomains exhibited a magnetic flux with left-hand spiral symmetry, which could be characterized by the geometric-phase coefficient of the negative integer. The co-doping of electrons and holes in an ultimate superconductor may be a solution for practical power transmission at room temperature.

Polar magneto-optical Kerr effect (P-MOKE) has found extensive applications in magnetic storage, magneto-optical sensors, and spintronic devices. In this study, we investigate the P-MOKE response of multilayer films composed of cobalt platinum (CoPt) alloys and aluminum nitride (AlN), fabricated via DC magnetron sputtering. We observe a magnetization-alignment-dependent behavior, with interference effects contributing to the overall Kerr rotation. Notably, a significant enhancement in P-MOKE is achieved in the substrate/AlN(20 nm)/CoPt(3 nm)/AlN(15 nm) structure, which is attributed to the interference effects induced by the AlN dielectric layer. Furthermore, a distinctive jump in the Kerr rotation hysteresis loop is observed in the substrate/AlN(20 nm)/CoPt(3 nm)/AlN(15 nm)/CoPt(3 nm) configuration, due to the antiparallel alignment of the magnetization between top and bottom CoPt layers. AlN-thickness-dependent behaviors in the P-MOKE signal have also been found in the CoPt/AlN/CoPt trilayer structure. The effective refractive index method and transfer matrix method are employed to quantitatively explain the anomalous Kerr rotation. This study highlights the exceptional sensitivity of P-MOKE to both magnetization configuration and multilayer structure, underscoring its potential for advanced magneto-optical applications.

In two-dimensional photonic crystals composed of the multiferroic terbium manganite (TbMnO3) crystal cylinders, we selected three-, four-, and six-fold spatial rotational symmetries to design the artificial lattice structure. Compared with two others, the six-fold symmetry opens and even widens the absolute bandgap in the far-infrared waveband at higher frequencies. When a static magnetic field is applied, it induces the broken time-reversal symmetry, which, in turn, arrows the bandgap. In all cases, the topological phase is robust. This symmetry engineering highlights an engineering strategy for photon-subclass far-infrared detectors, by magnetically manipulating the on-off state of absolute photonic bandgaps.

In this work, (NaBi)0.5−x(LiSm)xBi2Nb2O9 (NBN-xLS, x = 0.00–0.06) ceramics were fabricated by co-doping of LiSm into Na0.5Bi2.5Nb2O9. The traditional solid-phase technique was employed for the entire synthesis process. The impact of LiSm doping on the crystal structure, dielectric, ferroelectric, and piezoelectric properties, as well as the underlying conduction mechanisms in the NBN-xLS ceramics, was analyzed systematically. The XRD patterns and the Rietveld refinement revealed that lattice distortion reduced with an increase in the LiSm doping amount. The decrease in lattice distortion significantly contributed to its improved ferroelectric and piezoelectric characteristics. The results showed that the NBN-xLS ceramics were primarily p-type materials due to their bulk-limited conduction, with oxygen holes and vacancies acting as the conducting species, and the appearance of weak ion conduction at high temperatures. The NBN-0.04LS ceramic, in particular, displayed the highest performance, with Pr, Tc, and d33 values of 9.05 μC/cm2, 777 °C, and 25.2 pC/N, respectively. Additionally, the ceramic displayed remarkable thermal stability, with its d33 retaining 95.0% of its original value after annealing at 760 °C. These results demonstrate that LiSm co-doped Na0.5Bi2.5Nb2O9 ceramics have potential for use in high-temperature sensors.

The interface is an issue in the ferroelectric field effect transistor. In this work, the study presents a combined characterization of the subsurface structure and the electric polarization of (001)‐oriented and poled BaTiO 3 crystal sheets. The first layer is found from the last ≈1.22 Å of the crystal to its Ti─O surface, which holds the empty or partly‐filled pseudo excited states of high energy levels, to set up the potential well and trap compensation charges. The second layer from ≈2.45 to ≈1.75 Å beneath the surface, accommodates the distorted lattice, and particularly, the pairs of small polarons and O vacancies at the pseudo ground state and the pseudo excited states of low energy levels. As a concreteness of the depolarization field, the second layer generates the subsurface polaron‐type polarization of reverse ferroelectricity. Between these two layers, there is a gap of states with a thickness ≈0.53 Å. The state bilayer demonstrates a method to quantify the interface, proves the parasitic capacitance, validates the parallel‐plate capacitor configuration, and gives a telltale sign to the enhanced ferroelectric polarization, the surface proximity property, the flexoelectric effect, the insulating failure, and the photocatalytic phenomena.

In this article, compact millimeter-wave (mmWave) filtennas are proposed based on the multiparasitic structure incorporation technique to achieve high selectivity, and their working principle is systematically analyzed using equivalent lumped circuits. Initially, a single-polarized filtenna is designed in the form of a proximity-coupled stacked patch antenna. Cross and ring patches are employed to achieve compact size, while high selectivity is realized by incorporating multiparasitic structures, i.e., shorted stubs, ring patches, and C-shaped strips. Subsequently, the single-polarized filtenna is extended to a dual-polarized version by utilizing two sets of identical feeding structures, while maintaining high polarization isolation. Prototypes of both the single- and dual-polarized filtennas are fabricated and measured. The results indicate that the -10-dB impedance bandwidths of the filtennas cover a broad mmWave band ranging from 24.25 to 29.5 GHz, with out-of-band suppression exceeding 20 dB. Furthermore, two 1x4 arrays are constructed using the proposed single- and dual-polarized filtennas, respectively, incorporating essential decoupling structures to improve the port and polarization isolation. Experimental results confirm the exceptional scanning and filtering performances of the two arrays. The merits of all the proposed filtennas and arrays make them promising candidates for B5G/6G miniaturized wireless devices.

There is much interest regarding the “coupled ferroelectricity and superconductivity” in the two-dimensional material, bilayer Td-MoTe2; however, the value and the type of electric polarization are unknown. The device structure and the measurement method show that the measured material is the composite of the pseudo-bilayer quantum Hall system, with a thickness of about thirty-six nanometers. The derived dielectric hysteresis loops and the calculated electronic structure reveal that the condensed large polarons are responsible for the reverse ferroelectricity and the coupled superconductivity. The maximum value of polaron-type electric polarization is ~12 nC/μm2 or 1.2 × 104 μc/cm2.

We perform dielectric and impedance spectrums on the compressively-strained ceramics of multiferroic bismuth ferrite. The subsurface-nanolayer quasipolarons manifest the step-like characteristic of pressure-dependent transient frequency and, furthermore, pressure-dependency fails in the transformation between complex permittivity and electrical impedance, which is well-known in classic dielectric physics, as well as the bulk dipole chain at the end of the dissipation peak.

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.

MXenes are expected to exhibit excellent lithium-ion storage performance due to its good electron conductivity, tunable functional groups, and unique accordion-like structure. However, they suffer from low initial coulombic efficiency (ICE) caused by the trapping and the irreversible reaction between MXene nanosheets and lithium ions. In this work, we propose a facile d-band center regulation strategy via doping engineering to achieve tailorable surface chemistry of MXene, revealing the intrinsic effects of heteroatoms doping on surface chemistry and ICE. This strategy can be applied to various MXenes, which is verified in the case of V2-yCryC as well as TiNbC, and TiVC MXenes. Typically, the V1.8Cr0.2C MXene delivers a double lithium storage capacity in comparison to V2C MXene. Its ICE is improved from 60% to 86%, surpassing most state-of-the-art MXenes. Theoretical calculations reveal that the shift of the d-band center towards the Fermi level is induced by the introduction of Cr and responsible for the improved electrochemical performance. It increases its chemical affinity and absorbability for oxygen-containing functional groups and lithium ions, providing a favorable surface chemistry for efficient lithium storage. This work provides a new strategy to tailor the fine structures of MXenes for their further energy storage applications.

Tin monosulfide (SnS) serves as a promising anode material in lithium-ion batteries (LIBs) due to its high theoretical capacity. However, its low rate capability and cycle stability due to poor electrical conductivity and large volume change remain urgent issues to be resolved. Here, we provide an efficient and facile strategy to achieve three-dimensional (3D) freestanding sulfur and nitrogen co-doped SnS/graphene nanocomposite (SnS/3DSNG). Benefiting from excellent electronic conductivity, improved volume flexibility, short transport length, and numerous active sites, the nanocomposite exhibits high initial discharge capacity (1030 mA h g−1 at 1 A g−1), excellent cycling stability (530 mA h g−1 at 1 A g−1 after 500 cycles) and great rate performance. The pseudo-capacitance can be improved (93.9

With the development of electronic technology, flexible electromagnetic wave shielding materials have attracted considerable interests in various fields. However, multifunctional electromagnetic wave shielding materials with great flexibility, excellent efficiency, environmental-friendliness, and corrosion resistance are urgently needed to be investigated. Although several works have achieved such frameworks, the extremely complicated fabrication procedure largely restricts their broad application. Accordingly, we deliver a facile strategy to achieve flexible polypyrrole nanotube-polyethylene glycol-polyvinyl alcohol hydrogel (PPPg) for enhanced electromagnetic shielding behaviors. The shielding effectiveness of the prepared hybrid with a thickness of 2 mm can reach 21 dB from 8 to 12 GHz. Additionally, such a film provides excellent flexibility with an elastic deformation of 100.9% at 2.28 MPa. H-plasma processing further leads to the hydrophobic feature of the PPPg hydrogel, promoting its great corrosion resistance in the natural environment. Our hydrogel is expected to become a promising multifunctional flexible nanocomposite hydrogel for high-performance wearable devices.

MXenes have attracted wide attention in the field of energy storage due to their high electrical conductivity, good hydrophilicity and diversified surface terminals. Herein, Ti2C MXene film with good flexibility is successfully prepared which exhibits excellent gravimetric capacity in the currently reported MXene family. And the coupling mechanism of the surface terminations of Ti2C MXene in aqueous electrolytes on the capacitance behavior is proposed. The flexible Ti2C film directly used as electrode for supercapacitors shows good electrochemical performance with specific capacitance up to 382F g(-1) at 2 mV s(-1) and 265F g(-1) at 100 mV s(-1), indicating that it is a promising electrode material for supercapacitors.

The advanced spintronic devices demand a new routine of manipulating spin states effectively with low power consumption, fast switching, and non-volatility. Here, a photovoltaic heterojunction structure of (Cu, Ta)/Co40Fe40B20/(Ta, Cu) on a p-n junction Si wafer is proposed. The saturation magnetizations (M-s) tun -ability under sunlight illumination is decreased by & SIM;5-8 %. The first principle calculations reveal that the insert Cu or Ta layer promoted the photoelectron transmission, leading to a larger M-s tunability. Moreover, the Ta layer also generates a barrier between the p-n junction and CoFeB to keep the photoelectrons in the CoFeB layer, creating a non-volatility and sunlight/electrical dual-regulated tri-state magnetization change. Element-resolved X-ray magnetic circular dichroism (XMCD) measurement is also performed to determine the diminished intrinsic magnetism and corresponding non-volatility during sunlight illumination. These fundings explore a new method of magnetic modulation further to expand the non-volatile, low-power sunlight-driven spintronics.(c) 2022 Elsevier Ltd. All rights reserved.

With the introduction of a not fully screened polarization that leads to three magnetic subdomains nested in one ferroelectric domain, we identify it as the quasipolaron surface polarization in the electrode effect of bismuth ferrite. The remanent polarization at 40 Hz is about 439 mu C/cm2 in the dielectric hysteresis loop of a reverse S shape, accompanying the antiferromagnetic one of an S shape, which reveals that the surface is an indispensable part in spintronics.