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Epitaxial films of BiAl x Fe 1 − x O 3 (xBAFO) were grown on SrTiO 3 (STO) and SrRuO 3 buffered STO substrates using pulsed laser deposition. To understand the effects of Al substitution at the Fe-site of BFO, we systematically investigated its impact on the material's crystal structure, surface morphology, ferroelectric properties, and magnetic properties. Our x-ray diffraction analysis revealed that phase-pure xBAFO films can be stabilized for Al concentrations between 0% and 35%, without the formation of secondary phases, due to the isotypic crystal structures of BiAlO 3 and BiFeO 3. This allowed the rhombohedral structure of BAFO to be preserved. We then characterized the ferroelectric properties of xBAFO (0 ≤ x ≤ 0.25) by analyzing polarization-voltage hysteresis loops, which exhibited a transition from a nearly square shape to a more slanted shape with increasing Al substitution. Additionally, piezoresponse force microscopy revealed that the domain growth mode, shape, size, dimension, and nucleation play a crucial role in the switching behavior of ferroelectric materials. Furthermore, we observed a modest enhancement in magnetization due to the modified spin ordering of Fe atoms with Al substitution. Notably, the optimal ferroelectric and magnetic properties were achieved at an Al concentration of 15%. These findings suggest that BAFO is a promising magnetoelectric material with desired functionalities for realizing BFO-based next-generation non-volatile memory devices. [ABSTRACT FROM AUTHOR]

This study investigates the out-of-plane magnetization component of electrodeposited Ni90Fe10 thin films grown under different applied magnetic field conditions. The formation of stripe domains is gradual, as there is a thickness range in which the transcritical shape appears in the hysteresis loops, while only magnetic ripples are measured in the magnetic force microscopy images. For instance, samples deposited under the residual magnetic field generated by the switched-off magnetic stirrer exhibit the transcritical shape in the in-plane hysteresis loops at a thickness of 400 nm, even though corresponding magnetic force microscopy images do not reveal the presence of stripe domains. When a perpendicular magnetic field of 100 Oe is applied during growth, stripe domains become visible in microscopy images, along with the transcritical shape in the hysteresis loop at 400 nm. This implies that the critical thickness for stripe formation can be reduced by applying a perpendicular magnetic field during electrodeposition. We have experimentally confirmed that the larger the magnetic field applied in the out-of-plane direction during growth, the smaller the critical thickness. These results underscore the importance of controlling the external magnetic field during electrodeposition for more effective tuning of the magnetic textures in electrodeposited Ni90Fe10 films. [ABSTRACT FROM AUTHOR]

The phenomenon of exchange bias has been extensively studied within crystalline materials, encompassing a broad spectrum from nanoparticles to thin-film systems. Nonetheless, exchange bias in amorphous alloys has remained a relatively unexplored domain, primarily owing to their inherently uniform disordered atomic structure and lacking grain boundaries. In this study, we present a unique instance of exchange bias observed in Fe–B–Nb amorphous thin films, offering insights into its origins intertwined with the system's spin-glass-like behavior at lower temperatures. The quantification of exchange bias was accomplished through a meticulous analysis of magnetic reversal behaviors in the liquid-helium temperature range, employing a zero-field cooling approach from various initial remanent magnetization states (±MR). At reduced temperatures, the appearance of asymmetric hysteresis, a hallmark of negative exchange bias, undergoes a transformation into symmetric hysteresis loops at elevated temperatures, underscoring the intimate connection between exchange-bias and dynamic magnetic states. Further investigations into the magnetic thermal evolution under varying probe fields reveal the system's transition into a spin-glass-like state at low temperatures. We attribute the origin of this unconventional exchange bias to the intricate exchange interactions within the spin-glass-like regions that manifest at the interfaces among highly disordered Fe-nuclei. The formation of Fe-nuclei agglomerates at the sub-nanometer scale is attributed to the alloy's limited glass-forming ability and the nature of the thin-film fabrication process. We propose that this distinctive form of exchange bias represents a novel characteristic of amorphous thin films. [ABSTRACT FROM AUTHOR]

Fe films with thicknesses between 17 and 95 nm were grown with a nano-sheet morphology, which enabled their high uniaxial magnetic, transport, and optical in-plane anisotropies. The top edge of the nano-sheets was directly visualized as nano-string-like structures of approximately 12.5–14 nm width and 100–300 nm length. The hysteresis loops showed a clear easy direction of magnetization in the longitudinal direction of the nano-sheets, whereas the hard direction loops were anhysteretic, with no remanence and zero coercive field. The anisotropy field exhibited values between 70 and 111 kA/m depending on the thickness of the films, with the maximum value corresponding to a 34 nm thick sample. The resistance of the films was also found to be highly anisotropic. The ratio (R⊥–R||)/R|| was ≈86%, with R|| and R⊥ being the resistances in the parallel and perpendicular directions of the nano-sheets, respectively. Likewise, the reflectivity of the samples behaved anisotropically; the ratio (IReflmax–IReflmin)/IReflmax of the intensity of reflected light by the films reached up to 61% for 34 nm thick samples, achieving the maximum value, IReflmax, when the plane of the incident light coincided with the direction of the nano-sheets and the minimum, IReflmin, when this plane was perpendicular to the direction of the nano-sheets. The origin of these anisotropic behaviors was established. These anisotropic films with high magnetization and high uniaxial anisotropies at the nanoscale can be useful for microelectronics applications, for devices such as magnetic sensors and transducers, or for ultrahigh frequency inductors. [ABSTRACT FROM AUTHOR]

NaNbO3(NN)-based lead-free materials are attracting widespread attention due to their environment-friendly and complex phase transitions, which can satisfy the miniaturization and integration for future electronic components. However, NN materials usually have large remanent polarization and obvious hysteresis, which are not conducive to energy storage. In this work, we investigated the effect of introducing CaTiO3((1−x)NaNbO3-xCaTiO3) on the physical properties of NN. The results indicated that as x increased, the surface topography, oxygen vacancy and dielectric loss of the thin films were significantly improved when optimal value was achieved at x = 0.1. Moreover, the 0.9NN-0.1CT thin film shows reversible polarization domain structures and well-established piezoresponse hysteresis loops. These results indicate that our thin films have potential application in future advanced pulsed power electronics. [ABSTRACT FROM AUTHOR]

Over the last fifteen years, ferroelectric (FE) and antiferroelectric (AFE) ultra-thin films based on fluorite-structured materials have drawn significant attention for a wide variety of applications requiring high integration density. AFE ZrO2, in particular, holds significant promise for nanosupercapacitors, owing to its potential for high energy storage density (ESD) and high efficiency (η). This work assesses the potential of high-performance Hf1−xZrxO2 thin films encapsulated by TiN electrodes that show linear dielectric (LD), FE, and AFE behavior. A wake-up effect is observed for AFE ZrO2, a phenomenon barely reported for pure zirconium oxide and AFE materials in general, correlated with the disappearance of the pinched hysteresis loop commonly observed for Zr-doped HfO2 thin films. ESD and η are compared for FE, AFE, and LD samples at the same electrical field (3.5 MV/cm). As expected, ESD is higher for the FE sample (95 J/cm3), but η is ridiculously small (≈55%) because of the opening of the FE hysteresis curve, inducing high loss. Conversely, LD samples exhibit the highest efficiency (nearly 100%), at the expense of a lower ESD. AFE ZrO2 thin film strikes a balance between FE and LD behavior, showing reduced losses compared to the FE sample but an ESD as high as 52 J/cm3 at 3.5 MV/cm. This value can be further increased up to 84 J/cm3 at a higher electrical field (4.0 MV/cm), with an η of 75%, among the highest values reported for fluorite-structured materials, offering promising perspectives for future optimization. [ABSTRACT FROM AUTHOR]

Magnetoelectric composite materials, which exhibit both ferroelectric and ferromagnetic properties simultaneously, have attracted considerable interest for their potential in various applications such as microelectronics, memory devices, and spintronics. In this study, we investigated the synthesis, structural, morphological, electrical, and magnetic properties of multiferroic CoFe2O4/0.65BiFeO3-0.35PbTiO3 (CFO/65BF-35PT) composite thin films. These films were prepared using a high ferroelectric, morphotropic phase boundary (MPB) composition, 65BF-35PT, combined with a high magnetostrictive compound, CFO. Multilayered CFO/65BF-35PT composite films were spin-coated onto fluorine-doped tin oxide (FTO)/glass substrates using the sol-gel method, with variation in the solution molarity to achieve different layer thicknesses. Structural analysis revealed a perovskite phase for 65BF-35PT and a spinal structure for CFO, with the presence of rhombohedral and tetragonal polymorphs confirming MPB composition. Scanning electron microscope images demonstrated uniform growth of 1 μm thick composite films. Ferroelectric hysteresis loops exhibited considerable leakage current at room temperature, increasing with higher CFO content, while current versus voltage plots revealed ohmic conduction at low applied fields and space charge limited current (SCLC) conduction at high fields in all composite films. The crossover field between ohmic and SCLC conduction decreased with increasing CFO content. Moreover, room-temperature magnetic hysteresis loops showed a decrease in saturation and coercive field with increasing CFO concentration, and the temperature-dependent magnetization response indicated a monotonic decrease, with magnetization vanishing around 800 K, confirming the magnetic order of CFO. Our findings demonstrate that stable ferroelectric and ferromagnetic phases can be achieved at low temperatures by depositing composite films containing CFO/MPB on a low-cost FTO substrate. [ABSTRACT FROM AUTHOR]

Calculations and measurements of polarization-dependent soft X-ray scattering intensity are presented during a magnetic hysteresis cycle. It is confirmed that the dependence of the intensity on the magnetic moment can be linear, quadratic or a combination of both, depending on the polarization of the incident X-ray beam and the direction of the magnetic moment. With a linearly polarized beam, the scattered intensity will have a purely quadratic dependence on the magnetic moment when the magnetic moment is parallel to the scattering plane. However, with the magnetic moment perpendicular to the scattering plane, there is also a linear component. This means that, when measuring the hysteresis with linear polarization during a hysteresis cycle, the intensity will be an even function of the applied field when the change in the magnetic moment (and field) is confined within the scattering plane but becomes more complicated when the magnetic moment is out of the scattering plane. Furthermore, with circular polarization, the dependence of the scattered intensity on the moment is a combination of linear and quadratic. With the moment parallel to the scattering plane, the linear component changes with the helicity of the incident beam. Surprisingly, in stark contrast to absorption studies, even when the magnetic moment is perpendicular to the scattering plane there is still a dependence on the moment with a linear component. This linear component is completely independent of the helicity of the beam, meaning that the hysteresis loops will not be inverted with helicity. [ABSTRACT FROM AUTHOR]

The study investigates the effects of doping on the leakage current and ferroelectric properties of bismuth ferrite (BiFeO3) thin film-based heterostructures. The spin coating method has been employed to deposit thin films of BiFeO3 and heterostructures of TiO2/BiFeO3 and TiO2/BiFe0.95Mn0.05FeO3 on fluorine-doped tin oxide substrates. The ferroelectric behavior of the TiO2/BiFe0.95Mn0.05FeO3 films exhibited better ferroelectric hysteresis loop compared to the other prepared films. The ferroelectric behavior reveals the TiO2/BiFe0.95Mn0.05FeO3 heterostructure showed a significantly lower leakage current density compared to both the BiFeO3 thin film and TiO2/BiFeO3 heterostructure, and the TiO2/BiFe0.95Mn0.05FeO3 heterostructures are likely suitable for solar cell applications. FTO/TiO2/BiFe0.95Mn0.05FeO3/Au heterostructure thin films prepared by spin coating method. Structure and optical properties of TiO2/BiFe0.95Mn0.05FeO3 heterostructure thin films were investigated. TiO2/BiFe0.95Mn0.05FeO3 heterostructure thin films showed a low optical energy band gap of 2.25 eV. Enhanced ferroelectric property in TiO2 thin film composited with BiFe0.95Mn0.05FeO3 thin films. [ABSTRACT FROM AUTHOR]

The exchange bias (EB) is a unidirectional anisotropy that occurs, e.g., upon field‐cooling ferromagnet/antiferromagnet systems. In many material systems, the EB field is reduced from one hysteresis loop to the next measurement. This so‐called training effect (TE) has been investigated in experiments and by means of theoretical efforts by many research groups. The reduction of the EB field as a result of subsequent magnetization reversal processes is often fitted by a power law, usually with the exception of n = 1, or with an equation based on the discretized Landau–Khalatnikov equation, as first suggested by Binek. Few other models, usually with more fitting parameters, have been proposed yet. Herein, it is shown that for large numbers of subsequent magnetization reversal processes in Co/CoO thin film samples, a modified power law or a logarithmic fit can model the TE in most cases as well as the abovementioned, commonly used models. [ABSTRACT FROM AUTHOR]

Multiferroic (BiFeO3)1−x-(PbTiO3)x (1−x)BF−xPT thin films exhibit very high electromechanical properties in the vicinity of the morphotropic phase boundary (MPB), making them important candidates for use in several modern device applications. However, preparing high-quality (1−x)BF−xPT thin films is challenging due to the high conductivity caused by oxygen vacancies produced during the synthesis process. This study aims to understand the effect of size and porosity density on the electrical properties of (1−x)BF−xPT thin films. A series of (1−x)BF−xPT solid solution thin films were fabricated using the spin-coating method on Pt/TiO2/SiO2/Si(100) substrates through chemical solution deposition. X-ray diffraction studies revealed a polycrystalline structure. Surface SEM images showed that the films have a uniform surface with average grain sizes ranging between 50 and 200 nm and an average film thickness of 1.5 μm. A decrease in average pore size and an increase in the number of pores were observed with the increase in PT concentration in the prepared films. Ferroelectric characterization revealed that the films exhibit room-temperature ferroelectric hysteresis loops. Sources of various contributions to polarization were extracted from hysteresis loops, including true ferroelectric switching and space charge contributions. Thin films with 0.30 < x < 0.45 show higher remanent and saturation polarization values, suggesting that these compositions exhibit the MPB. The highest remanent polarization value (PR = 16.68 μC/cm2) was observed for the thin film with x = 0.40. The correlation between the phase, composition, film morphology, and ferroelectric response is described and discussed. [ABSTRACT FROM AUTHOR]

In this study, electron beam evaporated tungsten oxide (WO3) thin film (TF) has been investigated for both capacitive and resistive switching memory devices. The fabricated samples underwent annealing at a temperature of 500 °C. Capacitance–voltage (C–V) and conductance–voltage were found to decrease with the increase in frequency for both the as-depo and annealed Au/WO3 TF/Si devices. The decrease in the interface trap density (Dit) from 1.27 × 1011 eV−1 cm−2 (as-depo WO3 TF) to 1.81 × 1010 eV−1 cm−2 (annealed WO3 TF) was attributed to the reduced number of defects. A large memory window of 9.76 V at ± 10 V was exhibited for annealed WO3 TF in the C–V hysteresis loop. A stable high resistance state and low resistance state were obtained for the annealed device up to 105 s without any distinct deterioration. The effects of crystallization are comprehensively explored to explicate the alteration in the resistive switching characteristics and its fundamental mechanism. The observed alterations in resistive switching behavior have been attributed to the processes of charge-trapping de-trapping and the migration of oxygen vacancies within the film. Our work offers insights into the charge-trapping mechanisms in WO3 TF-based nonvolatile memory devices, highlighting the impact of annealing on their performance. [ABSTRACT FROM AUTHOR]

The resistance hysteresis of vanadium dioxide (V O 2 ) is a key feature in revealing mechanisms of a phase transition as well as emerging applications. In this study, a dynamical model based on random-resistor networks is developed to simulate the transport properties of V O 2 thin films. The reversible metal–insulator phase transition of each microscopic domain is captured by a modified Landau-type functional. The proposed model enables analysis of not only the formation of conducting filaments driven by an electric field, but also the thermal-driving reversal curves of resistance hysteresis. It is shown that the appearance of a hysteresis loop as well as the aggregation of metallic domains can be tuned via the interactions of each domain with its neighbors and the substrate. The interaction effects are vital for the persistence of metallic domains, which can re-trigger the insulating-to-metallic transition by a subthreshold voltage bias with the delay time much longer than the transition switching time. These results are in agreement with experimental observations and can be helpful in developing V O 2 -based key components ranging from infrared bolometers to the volatile resistive switches for neuromorphic computing. [ABSTRACT FROM AUTHOR]

The effect of ferromagnetic CaMnO3 (CMO) addition to structural, magnetic, dielectric, and ferroelectric properties of BiFeO3 is presented. X-ray diffraction and Raman investigation allowed the identification of a single pseudocubic perovskite structure. The magnetic measurement showed that the prepared films exhibit a ferromagnetic behavior at a low temperature with both coercive field and remnant magnetization increased with increasing CMO content. However, a deterioration of magnetization was observed at room temperature. Ferroelectric study revealed an antiferroelectric-like behavior with a pinched P–E hysteresis loop for 5% CMO doping BFO, resulting in low remnant polarization and double hysteresis loops. Whereas, high remnant polarization and coercive field with a likely square hysteresis loop are obtained for 10% CMO addition. Furthermore, a bipolar resistive switching behavior with a threshold voltage of about 1.8 V is observed for high doped film that can be linked to the ferroelectric polarization switching. [ABSTRACT FROM AUTHOR]

Exchange bias (EB) is a unidirectional anisotropy caused by interface coupling between a ferromagnet and an antiferromagnet. It causes a preferential direction of magnetization in the ferromagnet, which manifests as a shift of the hysteresis loop along the magnetic field axis. Here, we demonstrate a large EB of over 1000 Oe at 20 K in a twinned Co(111)/Co3O4(111) thin film epitaxially grown on sapphire(0001) with sixfold rotational lattice symmetry, which is among the highest values reported for Co/Co1−yO systems. In such systems, the effect intensity is largest along the magnetic easy axes, which usually results in an anisotropy of the EB in epitaxial interfaces. However, we observed identical EB values for 0°, 15°, and 30° angles between the magnetic field and the nearest Co[002] magnetic easy axes. The measurements imply a relaxation of the magnetization to the nearest easy axis, suggesting increasingly isotropic EB fields with higher orders of rotational lattice symmetry. [ABSTRACT FROM AUTHOR]

AgNbO3-based materials have attracted extensive attention in energy storage due to their double hysteresis loops, but they suffer from low breakdown strength (Eb). AgNbO3 films with few defects and small thickness exhibit high Eb, which helps to improve the energy storage performance. In this work, we successfully prepared AgNbO3 thin films on (110) SrTiO3 substrate using pulsed laser deposition technology. The AgNbO3 film shows good crystalline and relaxor ferroelectric behavior. A high Eb up to 1200 kV/cm is obtained in AgNbO3 film, which contributes to good recoverable energy storage density Wrec up to 10.9 J/cm3 and energy efficiency η of 75.3%. Furthermore, the Wrec remains above 2.9 J/cm3 and the η varies between 72.5% and 82.5% in a wide temperature range of 30–150 °C. This work reveals the great potential of relaxor ferroelectric AgNbO3 film for energy storage. [ABSTRACT FROM AUTHOR]

Dysprosium oxide (Dy2O3) and Cu/Dy2O3 thin films of thickness 117.14 nm and 258.30 nm, respectively were successfully deposited via a well-known DC-magnetron sputtering technique. Field emission scanning electron microscopy clarifies the growth of uniform and fine granular particles on silicon substrate. The hexagonal closed pack structure for both the thin films has been observed by the x-ray diffraction analysis and it was observed that by inclusion of copper the HCP structure of thin film was retain with a slight shift in the main peak. The reduction from 3.9 eV to 3.8 eV in the energy band gap value was observed by incorporation of copper ions Dy2O3 thin films. The M-H loops obtained through Vibrating Sample Magnetometer (VSM) shows that Dy2O3 thin film behave ferromagnetically at low temperature with a saturation magnetization value of 2860 emu/cc and evolves through its phase transition temperatures and behave paramagnetically at room temperature. In Cu/Dy2O3 case, the diamagnetic response of Cu dominates and produces reverse hysteresis loop at both temperatures make it a suitable candidate for energy and memory storage devices applications.

Smart multifunctional materials such as vanadium dioxide (VO2), which exhibit a reversible semiconductor-to-metal transition (SMT), provide a new route toward engineering high speed switchable devices. Here, we present a detailed report on the modulation in the electrical properties of VO2/Si heterostructures by application of an external electrical field across VO2 thin films. Single-phase VO2 thin films have been deposited on an Si(111) substrate using the pulsed laser deposition technique. The electrical transport behavior across the VO2/Si heterostructure has been studied in the temperature range of 35–105 °C, and a reversible SMT can be seen at 68 and 63 °C for heating and cooling cycles, respectively. The temperature-dependent resistance of the device shows a hysteresis loop around the transition temperature of the VO2 thin film. In addition, the device shows a significant change in junction current when an external bias is applied on the VO2 thin film, and this phenomenon has been utilized to study the switching behavior of the device. Such behavior is due to the change in interfacial barrier height because of the bias dependent tilting of electronic energy bands of the VO2 thin film. Our results offer novel opportunities to externally control the electrical transport of vertical heterostructures and can be beneficial for extending the notion of electrical field modulation in electrical switches and sensors. [ABSTRACT FROM AUTHOR]

We investigate the magneto-optical (MO) polar Kerr enhancement of Fabry–Pérot cavities with perpendicular magnetic anisotropy for chemical and biological sensing applications. The MO cavities consist of stacked films with a half-mirrored surface layer, a dielectric interference layer, a total-reflection mirror, and a magnetic metal layer. Co80Pt20 and Al-doped ZnO (AZO) thin films were utilized as the magnetic and interference layers, respectively. The cavities produce two types of MO enhancement depending on the thickness of the magnetic layer. The sample with a thick magnetic layer as a total-reflection mirror generates a single peak in the polar Kerr spectrum. Contrarily, inserting a several-nanometer-thick CoPt layer into the AZO layer produces a resonant-type spectrum. Although both samples generate large MO enhancement factors (>50), the magnetic properties significantly differ. The AZO/CoPt/AZO interference layer controls the crystalline and interface conditions and produces a square-shaped out-of-plane hysteresis loop with a large Kerr rotation angle. Moreover, the use of an ultrathin CoPt film significantly reduces the saturation magnetization field. Thus, Fabry–Pérot cavities with a CoPt/AZO interference layer may serve as high-sensitivity, low-energy-consumption sensor elements. [ABSTRACT FROM AUTHOR]

A resistive switching ZnO n–n homojunction diode fabricated with a stack of two dissimilar ZnO thin films shows promising characteristics necessary to address the crosstalk problem in a crossbar memory array. The device has a characteristic I–V-hysteresis loop in forward bias, in conjunction with its n–n junction characteristics. In the ac frequency range of 10 Hz–15 kHz, the area inside the hysteresis loop initially increased, reaching a maximum at 1 kHz, and then decreased with increasing frequency. The maximum in the area of the hysteresis loop corresponds to the accumulation of space charge at the interface. The resistivity of the device was found to vary from 5 to 100 kΩ in the bias range of 0–10 V and in the range of 106 Ω when reverse biased; the ratio of high resistive state to low resistive state has its maximum (∼2.4) at 1 kHz ac signal at 3 V. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2), which exhibits a metal–insulator phase transition at 70 °C, is known to alter its physical properties according to its surface morphology and fabrication process. The systematic investigation of a new fabrication method could not only clarify the origin of its phase transition but also advance progress in applications employing VO2 nanostructures. Here, we demonstrate the drastic enhancement of both the surface morphology and hysteresis of VO2 nanostructures composed of nanoparticles, by applying a sputtering deposition fabrication process, followed by lamp annealing. We investigated different growth conditions for VO2, especially using metallic precursor oxidation under a controlled pressure and temperature, and found that each growth condition led to different morphologies, nanoparticle sizes, and phase transition properties (hysteresis width). Despite a slight increase in particle diameter with annealing time and O2 pressure, the particle aggregation was found to substantially decrease. The temperature width of the hysteresis loop obtained by infrared light reflection measurements increased as the aggregation of VO2 nanoparticles decreased. During the cooling procedure, the transition of slightly aggregated VO2 nanoparticles was revealed to be a two-step process, with the lower transition temperature decreasing with an increase in particle isolation. Our results have the potential to elucidate the hysteresis-inducing mechanisms in VO2 and to aid the materialization of novel devices such as passive thermal control and thermal memory devices. [ABSTRACT FROM AUTHOR]

BaTiO3 thin films with different annealing times were grown on LSMO/STO (001) substrates by pulsed laser deposition. An interesting phenomenon of loss-and-reappearance of the interfacial layer in BaTiO3 was detected in the x-ray diffraction results, and the ordered–unordered–ordered lattice transformation caused by oxygen vacancies' filling was thought to be the reason. The ferroelectric domain was also confirmed to form during such an annealing process according to the piezoresponse force microscopy, transmission electron microscopy, and phase-field simulation. A Ti-displacement-rotation region considered an intermediate structure during the domain formation was observed at the interfacial layer of the 5.5-min-annealing film. Because of the oxygen deficiency and the effect of ferroelectric domain modulation of the built-in barrier height, a good memristive behavior with a resistive switching ratio of 1916 was obtained in the 10-min-annealing BaTiO3 (BTO) film, offering an avenue toward the application of oxygen-deficient BTO in neural network applications. [ABSTRACT FROM AUTHOR]

Exchange bias (EB) is a unidirectional anisotropy occurring in exchange-coupled ferromagnetic/antiferromagnetic systems, such as thin films, core–shell particles, or nanostructures. In addition to a horizontal shift of the hysteresis loop, defining the exchange bias, asymmetric loops and even vertical shifts can often be found. While the effect is used in hard disk read heads and several spintronics applications, its origin is still not fully understood. Especially in nanostructures with their additional shape anisotropies, interesting and often unexpected effects can occur. Here, we provide an overview of the most recent experimental findings and theoretical models of exchange bias in nanostructures from different materials. [ABSTRACT FROM AUTHOR]

Magnetic properties of Y0.67Sr0.33MnO3 (YSMO) and La0.67Sr0.33MnO3 (LSMO) thin films heterostructures (YSMO/LSMO) deposited on single-crystalline (001) SrTiO3 (STO), (001) LaAlO3 (LAO) and MgO substrates using pulsed laser deposition technique were investigated. Magnetization (M) vs. the applied field (H) measurements revealed shift in hysteresis loop showing the exchange bias effect of about 80 Oe for the heterostructures on LAO substrate, which was absent for those on STO substrates. In order to investigate this, single-layer LSMO layers were deposited on these substrates. X-ray diffraction patterns revealed significant compressive strain and a weaker tensile strain for LSMO films on LAO and STO substrates, respectively. Raman spectroscopy measurements further confirmed the lattice mismatch-induced strain in LSMO layer on LAO substrate. These different strain conditions in LSMO films on both the substrates are suggested to be contributing to the emergence of different magnetic ground states in these systems, which could be leading to pinning of spins at the interface and resulting in a significant exchange bias effect (EBE) on LAO substrate. [ABSTRACT FROM AUTHOR]

Unusual substitutional and interstitial solid solutions were observed in (1−x)Ba(Zr0.35Ti0.65)O3-xZnO thin films, where one Zn2+ cation substituted one B-site Zr4+/Ti4+ site and two Zn2+ cations substituted one A-site Ba2+ site simultaneously. Such a hybrid solid solution with an appropriate ZnO content remarkably increases both the electric breakdown strength (Eb) by widening the bandgap and the energy storage efficiency (η) by suppressing the hysteresis of the ferroelectric loop. As a result, the films with x = 0.2 show superior energy storage performance with a recoverable energy storage density (Wrec) of 130.3 J/cm3 and η of 89.1%. This work confirms the feasibility of forming an unconventional hybrid solid solution, which may shed light on further work on perovskite oxides with improved ferroic functionalities. [ABSTRACT FROM AUTHOR]

Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-BT) thin films were prepared via both chemical solution (CSD) and pulsed laser deposition (PLD). The structural, dielectric, and ferroelectric properties were investigated. High stability of the dielectric permittivity or TCC (∆ε/ε (150 °C) ≤ ±15%) over a wide temperature range from room temperature to 300 °C was obtained. Distinctly, the CSD film showed high TCC stability with variation of ±5% up to 250 °C. Furthermore, the CSD film showed an unsaturated ferroelectric hysteresis loop characteristic of the ergodic relaxor phase. However, the PLD one exhibited an almost saturated loop characteristic of the coexistence of both ergodic and non-ergodic states. The energy storage properties of the prepared films were determined using P–E loops obtained at different temperatures. The results show that these films exhibited a stable and improved energy storage density comparable to ceramic capacitors. Moreover, the CSD film exhibited more rigidity and better energy storage density, which exceeded 1.3 J/cm3 under a weak applied field of 317 kV/cm, as well as interesting efficiency in a large temperature range. The obtained results are very promising for energy storage capacitors operating at high temperatures. [ABSTRACT FROM AUTHOR]

The time-resolved magneto-optical Kerr effect in epitaxial thin films of the FePt compound and the FePt0.84Rh0.16 solid solution with the perpendicular magnetic anisotropy on MgO (001) substrates has been studied. The evolution of hysteresis loops at short (100 fs–1 ns) and long (1–20 ms) time scales after the excitation by a femtosecond light pulse has been studied. Long-lived nonthermal reduction of the coercive field has been detected. The coercive field is recovered in several milliseconds. It has been proposed to explain the observed phenomenon by the excitation of high-Q-factor acoustic resonances in the substrate/film system and to the strong magnetoelastic interaction in FePt and FePt0.84Rh0.16 films. [ABSTRACT FROM AUTHOR]

In this article, we examined the electromechanical behavior of Sn-substituted Lead Bismuth Zirconate Titanate thin films (PBZST thin films). Using the pulsed laser deposition technique (PLD), the thin film growth parameters of bismuth-doped PZST close to MPB were adjusted by varying the ∼(Zr, Sn)/Ti ratios. Thin films (∼250 nm) with the stoichiometric formula Pb0.985Bi0.01(Zr0.7Sn0.3)xTi1 –xO3, (x = 0.935, 0.940, 0.945, and 0.950) were grown on a Pt/TiO2/SiO2/Si substrate using PLD technique at optimized conditions. P-E loop confirms that MPB is near x = 0.945, and further PFM measurements also confirmed the same. Analyzing the PFM phase and amplitude hysteresis loops, local piezo-electric coefficient and remnant strain values were computed as d33 = 330 pm/V and 0.33 at the MPB composition (x = 0.945). [ABSTRACT FROM AUTHOR]

A ferroelectric memristor has attracted much attention due to convenient controlling by polarization switching, but the resistive switching has been attributed to the drift or charge trapping of defects. To distinguish the resistive switching mechanism between ferroelectric polarization switching and the normal resistive switching mechanism such as the drift or charge trapping of defects, BaTiO3 (BTO) thin films were grown on a (001) Nb:SrTiO3 single crystal substrate by pulsed laser deposition with high and low laser energy density. Based on a piezoelectric force microscope, ferroelectricity is found in BTO thin films grown at high laser energy density. X-ray photoelectron spectroscopy further confirms the existence of defects in the BTO films grown at low laser energy density. The high energy sample with low density of defects exhibits a resistance hysteresis loop but little current hysteresis loop, while the low energy sample with high density of defects shows a significant resistance and current hysteresis loop simultaneously. These results provide a deep understanding about the resistive switching from ferroelectric polarization switching and the drift or charge trapping of defects. [ABSTRACT FROM AUTHOR]

Domain configuration in epitaxial antiferroelectric films has been studied by X‐ray nanoscopy, with the extraction of information about the domain sizes beyond the beam‐size limit. The objective of this article is to understand how film thickness (the cases of 50 and 1000 nm are explored) and temperature (20 and 200°C) affect the nanodomain configuration of PbZrO3/SrRuO3/SrTiO3 thin films. It is found that the majority of antiferroelectric domains in both films are too small to be directly mappable, because many of them are simultaneously illuminated by the nanobeam (60 × 100 nm) most of the time. Nevertheless, these small sizes can be studied by analysing the diffraction peak width, which is, in the simplest approximation, inversely proportional to the domain size. With this approach it is identified that the characteristic (most probable) domain size does not depend on the film thickness and is ∼13 nm, while the scarcer larger domains do depend on it. An increase of the temperature to 200°C (just below the nominal antiferroelectric‐to‐cubic transition temperature) results in a slight increase in the characteristic size. These results are compared with those in ferroelectric films, where domain sizes are pronouncedly thickness dependent, and the relevant methodological question on the possibility of neglecting the interference of X‐ray waves scattered by different nanodomains in the nanodomain assembly is also discussed. [ABSTRACT FROM AUTHOR]

Fe-Ni-based nanocrystalline coatings with unique magnetic properties are widely used as soft magnetic materials and usually act as the core component in electronic devices. Nanocrystallized particles and thin films have become a popular contemporary research direction. Electrical explosion, characterized by an ultrafast atomization and quenching rate (dT/dt ~ 109–1011 K/s) for the material, is a unique approach for the rapid "single-step" synthesis of nanomaterials and coatings. In this study, experiments were carried out with intertwined wire under a directional spraying device in atmospheric Ar ambience. Two load systems of Fe-Ni and Fe-Ni-Co were considered in this work. Electrical parameters and high-speed camera images were obtained to reveal the physical mechanism and dynamic process of explosive spraying. The morphologic and crystallographic results were characterized by SEM and XRD. The magnetic properties were measured via VSM equipment, and the parameters of saturation magnetization Ms, residual magnetization Mr, and coercivity Hc were emphasized in the hysteresis loop pattern. The experimental results indicate that a dense coating was prepared with extremely low porosity, and the morphology of the coating surface shows different regions characterized by solidified chunks and loose particles. XRD patterns showed that crystalline structures were discrepant under two load systems with different Ni weight proportions. Magnetic measurements gave a thin and narrow hysteresis loop, which represents loops with good soft magnetic properties. Quantitatively, coercivity Hc decreased from 59.3 to 52.6 and from 121.0 to 49.9 for the coatings not containing and containing Co under parallel and perpendicular fields, respectively. [ABSTRACT FROM AUTHOR]

The longitudinal spin Seebeck effect (LSSE) has been investigated in ZnFe2O4 (ZFO) thin films on different substrates, such as Si (111), MgO (100), and SrTiO3 (100). The LSSE voltage signal exhibited a linear dependence on the temperature difference between both sides of the samples. The spin Seebeck coefficients were highly sensitive to the thermal conductivities of the magnetic layer and substrate, with values from 3 nV/k to 110 nV/K. Charge currents ( J c ) and spin currents ( J s ) densities were estimated. J s values are similar for the samples deposited on MgO and STO. The saturation magnetic field for the LSSE signal was reached with a magnetic field lower than its bulk counterpart. These results were related to the lattice mismatch between the ZFO films and the substrate, the magnetic response, and the anisotropies present in the samples since a twofold in-plane anisotropy was observed for the sample deposited on Si, while the samples deposited on MgO and SrTiO3 showed a fourfold in-plane anisotropy. Moreover, the presence of a notable perpendicular magnetic anisotropy in the thin films may be a consequence of the lattice mismatch and at the same time, it can cause the saturation in the LSSE voltage hysteresis loop measured as a function of the external magnetic be reached with a low magnetic field. [ABSTRACT FROM AUTHOR]

BiFe1-xZnxO3 (BFZO) (x = 0, 2%, 4%, 6%) thin films were successfully prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. The effect of Zn doping on the structure, surface morphology, leakage current density, ferroelectric and ferromagnetic properties of BiFeO3 (BFO) thin films were investigated systematically. XRD patterns show that all samples match well with the perovskite structure without impurity phase. SEM images show that BFZO thin films with x = 4% exhibit uniform fine grains and higher density, which is instrumental for the improvement of leakage current density. The leakage current density curve shows that BiFe0.96Zn0.04O3 thin films have the lowest leakage current density (J = 1. 56 x 10-6 A/cm²) under the electric field strength of 300 kV/ cm, which is three orders of magnitude lower than that of pure BFO thin films. Furthermore, BiFe0.96Zn0.04O3 thin film exhibits the largest remnant polarization (2Pr = 20. 91 μC/cm²) at room temperature, which is more than four times as large as that of pure BFO (2Pr = 4. 96 μC/cm²). Additionally, compared with BFO thin film, Zn doping also enhances the ferromagnetic properties of BFO thin films, and as Zn doping concentration increases, the saturation magnetization of BFZO thin films is significantly enhanced, which provides potential applications in information storage. [ABSTRACT FROM AUTHOR]

Polarization and breakdown strength as two sides of one coin are difficult to balance in one dielectric material, and so hierarchical heterostructure would be a good way to combine the advantages of each material enhancing energy density. In this work, high polarization Bi(Mg 0.5 Zr 0.5)O 3 (BMZ) and high breakdown strength Ba(Zr 0.25 Ti 0.75)O 3 (BZT) are chosen to prepare 1BMZ/4BZT/1BMZ (Type-A), 3BMZ/3BZT (Type-B) and 3(BMZ/BZT) (Type-C) hierarchical heterostructures thin films on Pt/Ti/SiO 2 /Si substrate via sol-gel method. Microstructure characteristics of thin films indicate that they possess well density, no crack and smooth surface. Thin films with Type-B structure possess a high dielectric constant of ∼500, which exceeds ∼150 of that with Type-A and Type-C structures. For energy storage properties, Type-B and Type-C thin films achieve high recoverable energy density W rec of 85.6 J/cm3 and 85.7 J/cm3 at low field of 2545 kV/cm and high field of 4980 kV/cm, respectively. The design of hierarchical heterosrtucture would break the limitation of low energy density in single material, and provide a new thinking for the applications of dielectric energy storage materials. Synergistic function of hierarchical heterostructure design and chemical composition selection to enhance energy storage properties at different electric fields. [Display omitted] [ABSTRACT FROM AUTHOR]

The magneto-optic Kerr effect can probe the process of magnetization reversal in ferromagnetic thin films and can, thus, be used as an alternative to magnetometry. The Kerr effect is wavelength-dependent and the Kerr rotation can reverse sign, vanishing at particular wavelengths. We investigate the epitaxial heterostructures of ferromagnetic manganite, La0.7Sr0.3Mn0.9Ru0.1O3, by using the polar Kerr effect and magnetometry. The manganite layers are separated by or interfaced with a layer of nickelate, NdNiO3. The Kerr rotation hysteresis loops of trilayers, with two manganite layers of different thicknesses separated by a nickelate layer, have intriguing humplike features when measured with light of 400 nm wavelength. By investigating additional reference samples, we disentangle the contributions of the individual layers to the loops: we show that the humps originate from the opposite sense of the Kerr rotation of the two different ferromagnetic layers, combined with the additive behavior of the Kerr signal. The change of sign of the Kerr rotation for the thinner manganite layer is most likely caused by optical interference. [ABSTRACT FROM AUTHOR]

The effect of epitaxial strain on the electrical properties of ferroelectric films has been widely investigated. However, this kind of strain is generally attributed to the substrate clamping constraints and is easily relaxed when the thickness of films is over 100 nm. In this work, a vertically epitaxial strain was introduced into lead-free piezoelectric K0.5Na0.5NbO3 films to improve the electrical properties of ferroelectric films. Two-phase, vertically epitaxial composite KNN-ZnO thin films were grown on the (001) STO substrate using a pulsed laser deposition (PLD) method. The highly (001) preferentially oriented KNN phase and (11 2 ¯ 0)-oriented ZnO phase were orderly arranged. Two types of morphologies of "square-like" and "stripe-looking" grains were observed in the surface image. An asymmetric "square" out-of-plane phase hysteresis loop and a "butterfly" displacement loop were exhibited in the KNN phase, whereas the ZnO phase showed a closed phase hysteresis loop and a slim displacement-voltage loop. Two different kinds of polarization behaviors for domains were also observed under applied electric fields, in which the domain of the KNN phase is easily switched to the opposite state, whereas the ZnO phase keeps a stable domain state when applying a DC bias of ±50 V. the vertically epitaxial growth of the KNN-ZnO composited films in this work provides a new way to fabricate complex nanoscale materials. [ABSTRACT FROM AUTHOR]

The critical‐element‐free ε‐Fe2O3 ferrimagnet exhibits giant magnetic coercivity even at room temperature. It is thus highly attractive material for advanced applications in fields such as spintronics, high‐density data storage, and wireless communication. However, a serious obstacle to overcome is the notoriously challenging synthesis of ε‐Fe2O3 due to its metastable nature. Atomic layer deposition (ALD) is the state‐of‐the‐art thin‐film technology in microelectronics. Herein, it is demonstrated that it has also true potential for the fabrication of amazingly stable in situ crystalline and high‐performance ε‐Fe2O3 thin films from simple (FeCl3 and H2O) chemical precursors at a moderately low deposition temperature (280 °C). Standard X‐ray diffraction and Fourier transfer infrared spectroscopy characterization indicates that the films are of high level of phase purity. Most importantly, precise temperature‐dependent 57Fe Mössbauer spectroscopy measurements verify that the hematite (α‐Fe2O3) trace in the films is below 2.5%, and reveal the characteristic low‐ and high‐temperature transitions at 208–228 K and ≈480 K, respectively, while magnetization measurements confirm the symmetric hysteresis loops expected for essentially phase‐pure ε‐Fe2O3 films. Excitingly, the highly c‐axis oriented film growth, the overall film quality, and the unique magnetic properties remain the same, independently of the substrate material used. [ABSTRACT FROM AUTHOR]

Structural, ferroelectric, and magnetic properties of lead-free bilayer composite films with composition (K, Na, Li) NbO3-CoZnFe2O4 (P-S) and CoZnFe2O4-(K, Na, Li) NbO3 (S-P) layers deposited on Pt/Si substrates by a pulsed laser deposition technique have been studied. Structural analysis carried out by X-ray diffraction and Raman scattering confirmed the formation of individual phases of perovskite and spinel without any intermediate/secondary phase. To probe the stoichiometric elemental composition and cationic distribution at the interstitial sites, X-ray photoelectron spectroscopy measurement was carried out, which confirmed the mixed state of Fe-ions valence, while the Zn2+ state was retained. Ferroelectric and ferromagnetic behavior of the bilayered films was observed concurrently depending upon the growth sequence adopted. Magnetic properties of the film with spinel on the top layer exhibited higher saturation magnetization. Dielectric permittivity follows the Maxwell–Wagner polarization caused by thermally agitated carriers. Appreciable ferroelectric properties were achieved in S-P films while the P-S film exhibited a lossy ferroelectric hysteresis loop, which is attributed to a high leakage current value. [ABSTRACT FROM AUTHOR]

An ilmenite structure was maintained with better crystalline characteristics which were determined from structural examinations employing x-ray diffraction of thermally evaporated NiTiO3 (NTO) thin films on Si (100) substrates. NiO6 and TiO6 octahedra are arranged in alternating layers in the lattice structure of NTO. Atomic force microscopy, which highlights the structure of the film surface, was used to assess the thin film microstructure and surface roughness. NTO preferentially absorbs ultraviolet radiation below 360 nm, visible light in the wavelength range from 420 nm to 540 nm and above 700 nm. NTO displays a band gap of 2.17 eV and exhibits direct band gap semiconductor characteristics. Corresponding to photon energy of 2.7 eV, 2.5 eV and 1.5 eV, NTO shows clear absorbance peaks at 448 nm, 502 nm and 743 nm, respectively. It is hypothesized that the peaks of NTO's visible light absorbance result mostly from the charge transfer transitions d → d of Ni inside its valence band. The films have been further characterized by x-ray photoemission spectroscopy and valence band spectroscopy, with a range of photonic energy resulting in the phenomenon of resonance photoemission spectroscopy (RPES) in accordance to find out the electronic spectra of NTO which eliminates the possibility of metal clusters in NTO films. The RPES spectra indicate that the Ti 3d (Ti3+ defect states) and O 2s are strongly hybridized. The magnetic hysteresis loop demonstrated that the NTO films may exhibit superparamagnetic behavior at 300 K. These characterization techniques help to understand its electronic and magnetic properties, which are important in photocatalytic devices. [ABSTRACT FROM AUTHOR]

In condensed matter physics, oxide materials show various intriguing physical properties. Therefore, many efforts are made in this field to develop functional oxides. Due to the excellent potential for tin‐based perovskite oxides, an expansion of new related functional compounds is crucial. This work uses a heteroepitaxial approach supported by theoretical calculation to stabilize PbSnO3 thin films with different orientations. The analyses of X‐ray diffraction and transmission electron microscopy unveil the structural information. A typical antiferroelectric feature with double hysteresis and butterfly loops is observed through electrical characterizations consistent with the theoretical prediction. The phase transition is monitored, and the transition temperatures are determined based on temperature‐dependent structural and electrical characterizations. Furthermore, the microscopic antiferroelectric order is noticed under atomic resolution images via scanning transmission electron microscopy. This work offers a breakthrough in synthesizing epitaxial PbSnO3 thin films and comprehensively understanding its anisotropic antiferroelectric behavior. [ABSTRACT FROM AUTHOR]

A high-speed and high-power current measurement instrument is described for measuring rapid switching of ferroelectric samples with large spontaneous polarization and coercive field. Instrument capabilities (±200 V, 200 mA, and 200 ns order response) are validated with a LiTaO3 single crystal whose switching kinetics are well known. The new instrument described here enables measurements that are not possible using existing commercial measurement systems, including the observation of ferroelectric switching in large coercive field and large spontaneous polarization Al0.7Sc0.3N thin films. [ABSTRACT FROM AUTHOR]

This paper describes two perovskite high entropy oxide (PHEO) compositions: Pb(Hf0.2Zr0.2Ti0.2Nb0.2Mn0.2)O3 (Mn PHEO) and Pb(Hf0.2Zr0.2Ti0.2Nb0.2Al0.2)O3 (Al PHEO). Powders are prepared by conventional solid state sintering by first pre‐reacting the B‐site oxides, then adding PbO. Phase pure Mn PHEO powder is obtained following calcination of the mixed powders at 750 °C for 240 min; however, secondary phases persisted in Al PHEO for heat treatments from 750 °C to 1200 °C. The Mn PHEO undergoes an entropy‐driven phase transformation. Thin films of these compounds are synthesized by pulsed laser deposition (PLD) on a lead zirconate titanate seed layer on Pt‐coated SiO2/Si. The dielectric response of the Mn PHEO films show some contribution from space charge polarizability; in contrast, the Al PHEO films show a slim ferroelectric hysteresis loop and relaxor‐like characteristics. The Al PHEO has a dielectric permittivity of ≈2000 with a loss tangent <0.05 from 100 Hz to 100 kHz; it has a dielectric maximum at 105 ± 0.5 °C and a Burns' temperature of 234 ± 0.5 °C. Indirect measurements based on the Maxwell‐relations yielded a maximum electrocaloric temperature change of 8.4 K at 180 °C under the applied electric field of 1186 kV cm−1. [ABSTRACT FROM AUTHOR]

The multiferroic properties of BiCrO3 (BCO) bulk and thin films are investigated for the first time using a microscopic model. The influence of ion doping on the multiferroic properties of BCO is also studied because the doping process changes the physical properties and can be used for potential applications in magnetoelectronic devices. The magnetization M increases by Mn and decreases by Ga‐ion doping whereas the Néel temperature TN decreases in both cases. There are some discrepancies by polarization whether it is ferroelectric or antiferroelectric. It is shown that bulk pure BCO is antiferroelectric because the electric field dependence of polarization P shows a double hysteresis loop and the dielectric constant has no anomalies at TN. In Ga‐, Mn‐ or Ti‐doped BCO a ferroelectric polarization appears. The specific heat shows a peak at TN for BCO. By Ga doping, this peak vanishes with increasing x. The multiferroic behavior of BCO is demonstrated in the magnetic field dependence of the dielectric constant. In BCO thin films, ferroelectric and ferromagnetic behavior is observed. [ABSTRACT FROM AUTHOR]

A Faraday rotation spectroscopy (FRS) technique is presented for measurements on the micrometer scale. Spectral acquisition speeds of about two orders of magnitude faster than state‐of‐the‐art modulation spectroscopy setups are demonstrated. The experimental method is based on charge‐coupled‐device detection, avoiding speed‐limiting components, such as polarization modulators with lock‐in amplifiers. At the same time, FRS spectra are obtained with a sensitivity of 20 µrad (0.001°\[0.001{\bm{^\circ }}\]) over a broad spectral range (525–800 nm), which is on par with state‐of‐the‐art polarization‐modulation techniques. The new measurement and analysis technique also automatically cancels unwanted Faraday rotation backgrounds. Using the setup, Faraday rotation spectroscopy of excitons is performed in a hexagonal boron nitride‐encapsulated atomically thin semiconductor WS2 under magnetic fields of up to 1.4 T at room temperature and liquid helium temperature. An exciton g‐factor of −4.4 ± 0.3 is determined at room temperature, and −4.2 ± 0.2 at liquid helium temperature. In addition, FRS and hysteresis loop measurements are performed on a 20 nm thick film of an amorphous magnetic Tb20Fe80 alloy. [ABSTRACT FROM AUTHOR]

The current approach to achieving superior energy storage density in dielectrics is to increase their breakdown strength, which often incurs heat generation and unexpected insulation failures, greatly deteriorating the stability and lifetime of devices. Here, a strategy is proposed for enhancing recoverable energy storage density (Wr) while maintaining a high energy storage efficiency (η) in glassy ferroelectrics by creating super tetragonal (super‐T) nanostructures around morphotropic phase boundary (MPB) rather than exploiting the intensely strong electric fields. Accordingly, a giant Wr of ≈86 J cm−3 concomitant with a high η of ≈81% is acquired under a moderate electric field (1.7 MV cm−1) in thin films having MPB composition, namely, 0.94(Bi, Na)TiO3‐0.06BaTiO3 (BNBT), where the local super‐T polar clusters (tetragonality ≈1.25) are stabilized by interphase strain. To the knowledge of the authors, the Wr of the engineered BNBT thin films represents a new record among all the oxide perovskites under a similar strength of electric field to date. The phase field simulation results ascertain that the improved Wr is attributed to the local strain heterogeneity and the large spontaneous polarization primarily is originated from the super‐T polar clusters. The findings in this work present a genuine opportunity to develop ultrahigh‐energy‐density thin‐film capacitors for low‐electric‐field‐driven nano/microelectronics. [ABSTRACT FROM AUTHOR]

We have studied magnetic tunnel junction (MTJ) thin-film stacks using the First Order Reversal Curve (FORC) method. The FORC distribution of these MTJs has very sharp features, unlike most particulate systems or patterned films. These features are hard to study using conventional FORC analysis programs that require smoothing because this washes out the features. We have used a new analysis program (FORC+) that is designed to distinguish fine-scale features from noise without the use of smoothing, to identify these features and gain information about the switching mechanism of the stack. [ABSTRACT FROM AUTHOR]

Tuning and stabilizing a large imprint in epitaxial relaxor ferroelectric thin films is one of the key factors for designing micro-electromechanical devices with an enhanced figure of merit (FOM). In this work, epitaxial 500 nm-thick 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 (PMN–33PT) films, free from secondary phases and with extremely low rocking curves (FWHM < 0.05°), are grown on ScSmO3 (SSO) and DyScO3 (DSO) substrates buffered with SrRuO3 (SRO). The PMN–33PT is observed to grow coherently on SSO substrates (lattice mismatch of −0.7%), which is c-axis oriented and exhibits large tetragonality compared to bulk PMN–33PT, while on DSO substrates (lattice mismatch of −1.9%), the PMN–33PT film is almost completely relaxed and shows reduced tetragonality. Due to the compressive epitaxial strain, the fully strained PMN–33PT film displays typical ferroelectric P–E hysteresis loops, while the relaxed sample shows relaxor-like P–E loops. Samples present large negative imprints of about −88.50 and −49.25 kV/cm for PMN–33PT/SRO/SSO and PMN–33PT/SRO/DSO, respectively, which is more than threefold higher than the coercive field. The imprint is induced by the alignment of defect dipoles with the polarization and is tuned by the epitaxial strain. It permits the stabilization of a robust positive polarization state (Pr ∼ 20 μC/cm2) and low dielectric permittivity (<700). In addition, the relaxed PMN–33PT film shows improved piezoelectric properties, with a 33% enhancement in d33,eff relative to the fully strained sample. The obtained low dielectric permittivity and the high piezoelectric coefficients at zero electric field in the studied PMN–33PT films hold great promise to maximize the FOM toward applications in piezoelectric devices. [ABSTRACT FROM AUTHOR]

Epitaxial strain modifies the physical properties of thin films deposited on single-crystal substrates. In a previous work, we demonstrated that in the case of La2/3Ca1/3MnO3 thin films the strain induced by the substrate can produce the segregation of a non-ferromagnetic layer (NFL) at the top surface of ferromagnetic epitaxial La2/3Ca1/3MnO3 for a critical value of the tetragonality τ, defined as τ = |c − a|a, of τC ≈ 0.024. Although preliminary analysis suggested its antiferromagnetic nature, to date a complete characterization of the magnetic state of such an NFL has not been performed. Here, we present a comprehensive magnetic characterization of the strain-induced segregated NFL. The field-cooled magnetic hysteresis loops exhibit an exchange bias mechanism below T ≈ 80 K, which is well below the Curie temperature of the ferromagnetic La2/3Ca1/3MnO3 layer. The exchange bias and coercive fields decay exponentially with temperature, which is commonly accepted to describe spin-glass (SG) behavior. The signatures of slow dynamics were confirmed by slow spin relaxation over a wide temperature regime. Low-energy muon spectroscopy experiments directly evidence the slowing down of the magnetic moments below ~100 K in the NFL. The experimental results indicate the SG nature of the NFL. This SG state can be understood within the context of the competing ferromagnetic and antiferromagnetic interactions of similar energies. [ABSTRACT FROM AUTHOR]

We investigate the magnetic phase transition in a thin film with an antidote lattice by computer simulation. A lattice of non-magnetic antidotes is present in a thin film of several atomic layers. The antidotes form a rectangular lattice. We are looking at two forms of antidotes. The Ising model and Wolf' cluster algorithm simulate the system's magnetic behavior. Antidotes act on additional surfaces of the system. This results in a change in the Curie temperature of the system. Dependence of phase transition temperature on holes size and shape is obtained. The phase transition temperature depends on the size of the hole by logarithmic law. The Curie temperature for triangular holes is lower than for square holes. We investigated the magnetization of a thin film with an antidote lattice and constructed a hysteresis loop. The hysteresis loop expands as the hole size decreases. Coercive force depends on the size and shape of the holes. Coercive force varies by nonlinear law. [ABSTRACT FROM AUTHOR]

CoNi films were elaborated by electrodeposition onto FTO substrates using a chloride bath with a metallic ion molar ratio [Co2+]/[Ni2+] equals 1/1. Three samples were elaborated for different potentials ranging from −1.6 to −1.5 V. The structure and the morphology of CoNi films were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The chemical compositions are obtained using energy dispersive X-ray (EDX) and the magnetic properties were studied using a vibrating sample magnetometer (VSM). From X-ray diffraction, we have shown the presence of the FCC phase of CoNi binary alloy with a well-pronounced texture along the < 111 > , < 200 > , and < 220 > planes for all samples. We have found that the applied potential has an influence on crystallite sizes. Besides, a moderate change in the lattice parameter has been observed with increasing applied potential. The AFM images show that the applied potential changes the morphology and the surface roughness of CoNi films. In addition, the SEM images confirm the granular morphology of CoNi deposits and show a good relationship between voltage and grain size. The EDX spectrums confirm the deposition of the cobalt and the nickel on the FTO substrate and show the precedence deposition of Co compared with Ni. The extracted coercive field Hc and squareness from the hysteresis loops explained the good correlation between the magnetic and structural properties of CoNi thin films. [ABSTRACT FROM AUTHOR]