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This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co3O4) or cobalt ferrite (CoFe2O4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co3O4@P3HB and CoFe2O4@P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co3O4 and CoFe2O4 NPs and the P3HB, Co3O4@P3HB and CoFe2O4@P3HB films. The optical band gap for Co3O4 and CoFe2O4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co3O4 and CoFe2O4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe2O4 nanoparticles and CoFe2O4@P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe2O4@P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles. [ABSTRACT FROM AUTHOR]

The present study reveals the synthesis of Iron oxide nanoparticles (IONPs) by varying the molar ratio of ferric (Fe3+) to ferrous (Fe2+) ions via chemical coprecipitation method for the study of cationic distribution of Fe‐ions and its potential application for magnetic hyperthermia therapy (MHT). X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS), were used to characterize the physicochemical properties. Several structural parameters were estimated using the Rietveld refinement, resulting in structural modelling verified by magnetic characteristics. A vibrating sample magnetometer (VSM) assessed the magnetic hysteresis loop at room temperature in a field range of ±15 kOe, revealing superparamagnetic behavior for the ratio Fe2+/Fe3+ 1:2. The saturation magnetization (Ms) of IONPs increased with the increasing Fe2+ concentration and attained a maximum value of 60.21 emu g−1 at a molar ratio of 2:1. The potential of the inductive heating capability of IONPs in an alternating current magnetic field (AMF) was studied to treat localized MHT. The changes in magnetic properties and inductive heating properties of IONPs are associated with the cationic distribution of Fe2+ at the tetrahedral (A) and octahedral (B) sites of crystal structure. The variation in cationic properties at the A and B sites may result in varying/tuneable magnetic properties, affecting the overall heating profiles of hyperthermia. [ABSTRACT FROM AUTHOR]

The structural and electromagnetic properties of various Ba1−x(Sr0.5Ni0.5)xTiO3 are extensively investigated. X‐ray diffraction and Rietveld refinement are used to perform a structural study. With doping substances, bulk and theoretical densities decrease. The crystallite size is calculated using Scherrer and Williamson–Hall method. The microstructural properties are examined using images from field‐emission scanning electron microscope. The observed values of dielectric constants are found to agree with the porosity‐corrected dielectric constants. The nonlinear modified Debye equation (NLMDE) displays a reasonable goodness of fit value for the first five samples. A small polaron hopping mechanism may be responsible for the frequency‐dependent AC conductivity observed in all samples confirming the Jonscher power law. It is discovered that permeability initially increases and then decreases with doping substances. Initial permeability, experimental data from the magnetic hysteresis (M–H) curve, and law‐of‐approach‐to‐saturation techniques show that Ba0.85(Sr0.5Ni0.5)0.15TiO3 and Ba0.75(Sr0.5Ni0.5)0.25TiO3 ceramics have enhanced electromagnetic properties. These ceramics are useful for fabricating electromagnetic sensors. [ABSTRACT FROM AUTHOR]

In this study, we report the biosynthesis of Nickel ferrite using Ocimum sanctum leaf extract (OSLE@NiFe2O4). The single-phase cubic spinel structure of the synthesized nickel ferrite was confirmed by powder X-ray diffraction (PXRD) analysis. Structural characteristics were further examined using FTIR analysis. Optical and morphological properties were investigated through UV–DRS and FESEM studies. The magnetic hysteresis loop (M-H loop) confirmed the superparamagnetic nature of OSLE@NiFe2O4 nanoparticles. The photocatalytic degradation of Congo Red (CR) dye by the synthesized OSLE@NiFe2O4 nanoparticles was explored, revealing a pseudo-first-order kinetic behavior with a degradation efficiency of 99.9% and a rate constant of 0.06min−1. These findings demonstrate the superior photocatalytic activity of the biosynthesized nickel ferrite nanoparticles, highlighting their significant potential for efficient dye removal. [ABSTRACT FROM AUTHOR]

Photocatalysts that combine with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. A series of Cd 0.4 Co 0.6 Dy X Ce X Fe 2-2X O 4 spinel nano ferrites (nFs) were synthesized by using a highly efficient low-temperature method of citrate sol-gel auto-combustion for Methylene Blue (MB) dye degradation photocatalysts under visible light irradiation that combines with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. The recycled MB is one of the hazardous textile dyes that is used extensively but causes risks for both humans and the environment. The prepared Dy3+ and Ce3+ doped Cd–Co nFs were polycrystalline with cubic structure, and crystalline size was increased from 15.78 to 21.02 nm with higher crystallinity, and the surface morphology changes from a spherical shape to a hexagonal shape with higher doping concentrations. The direct optical band gap values are increased. FTIR spectra reveal the stretching vibrations along the [M↔O] bond tetrahedral (A) and octahedral (B) sites. HRTEM results revealed that the prepared Cd–Co nFs have higher crystalline nature and high porosity. VSM indicates the sample's soft magnetic action and hysteresis loops showed the highest saturation magnetization (Ms) is 12.243 emu/g, and retentivity increases around 6.038 emu/g, decreasing the dielectric tangent loss, dielectric constant and dielectric loss. The AC conductivity raised with applied frequency. The PL gives a blue emission, and photocatalytic has the highest degradation activity 40.93 % of MB would be successful after 120 min irradiation of X = 0.07 Dy3+ and Ce3+ doped Cd–Co nFs. [Display omitted] [ABSTRACT FROM AUTHOR]

This study described a method for determining the magnetic field in transformer steel sheets for any magnetisation direction. In the proposed approach, limiting hysteresis loops for the rolling and transverse directions were used. These loops, which were determined separately in both directions, were modified depending on the direction of magnetisation. The assumed area of the magnetic field occurrence was divided into elementary segments, and the appropriate components of field strength and flux density were assigned to the edges and elementary segments of the grid dividing this area. The relationships between the flux density and field strength along both the rolling and transverse directions in the elementary segments were introduced into the equations of the magnetic field distribution, which were based on Maxwell's equations in the integral form. These equations facilitated the determination of changes in the magnetic field, considering the magnetic hysteresis. The correctness of these equations was validated through comparisons of the results of numerical calculations with the analogous results of measurements performed using a laboratory package of transformer sheets. [ABSTRACT FROM AUTHOR]

In this work, the Ni1-xMoxO, (x = 0.000, 0.025, 0.050, 0.075, 0.100, and 0.150) nanoparticles were prepared employing the coprecipitation method. The X-ray diffraction (XRD) confirmed that all the samples have a face-centered cubic (FCC) structure with no secondary phases by the effect of the Mo-doping. The Mo-dopants yielded smaller crystallites, reaching a size of 9 nm with x = 0.150. The transmission electron microscope (TEM) images revealed agglomerated NiO nanoparticles with nearly spherical shapes varied to elliptical-like shapes upon increasing Mo concentration. The energy dispersive X-ray (EDX) confirmed the purity of the synthesized samples. The XPS analysis confirmed the valence states of the presented elements in the samples as Ni2+, Ni3+, Mo6+, and O2− ions. The XPS detected the reduction of the nickel and oxygen vacancies, by studying the ratio of Ni2+/Ni3+ and lattice oxygen (OL) to vacant oxygen (OV) peaks. The Raman analysis demonstrated the active vibrational modes of NiO, for all the samples, along with stretching Mo = O bonds for the doped samples. The Photoluminescence (PL) spectroscopy was employed to study the near band edge and deep level emissions, giving insight to the defect levels within the band gap. The PL affirmed the decrease of the oxygen vacancies upon Mo-doping. Besides, the magnetic hysteresis measurements at room temperature revealed the superparamagnetic contribution embedded in the antiferromagnetic matrix of NiO. The magnetization was tuned by Mo doping concentration, where it affected the saturation magnetization, coercivity, and remnant magnetization. Mo dopant can modify the magnetic property of NiO nanoparticles and can be a potential candidate in biomedical field and data storage applications. [ABSTRACT FROM AUTHOR]

Soft magnetic films play a crucial role in numerous technological applications, such as magnetoelectronics, telecommunications, and magnetic recording, and the tuning of properties to obtain high-efficiency demands searching new materials and controlling thickness and compositions. In this regard, we report a systematic investigation of structural, morphological, electrical resistivity, and temperature-dependent magnetic properties of single-layer amorphous Fe70Co15Zr7B5Cu3 HITPERM (t = 5–100 nm) films deposited on a low-cost thermally oxidized Si substrate. Structural studies (XRD and TEM) reveal an amorphous nature in all as-deposited films. Surface morphology shows that the average roughness increases with increasing t up to 50 nm and then decreases at higher thicknesses. The electrical resistivity decreases rapidly as t increases from 5 to 10 nm and then is invariant for films with t ≥ 30 nm. Interestingly, the variation of resistivity follows the Boltzmann fitting. These films exhibit tunable magnetic properties between soft (t < 20 nm) and semi-hard (20 nm < t < 70 nm) properties with rectangular-type magnetic hysteresis loops having ~ 100% remanence ratios (Mr/Ms), low coercivity (Hc < 2.5 kA/m), and low saturation magnetic field (Hs < 3 kA/m) for t ≤ 70 nm. Transcritical hysteresis loop with a large Hc > 6.7 kA/m, high Hs > 26.5 kA/m, and reduced Mr/Ms ~ 55% is observed for t = 100 nm film. High-temperature thermomagnetization curves display two magnetic phase transitions (TC) corresponding ferromagnetic state to a paramagnetic state of the amorphous phase (at 820 K during warming) and nanocrystalline phase (at 1003 K during cooling). The observed results of HITPERM films with large TC naturally make it a potential choice for applications not only in magnetoelectronics at room temperature but also for aircraft power devices at higher temperatures. [ABSTRACT FROM AUTHOR]

Bi‒Sr‒Ca‒Cu‒O polycrystalline high-temperature superconductors with the 2–2-2–3 structure have been comprehensively studied, their properties have been described, and features of the small magnetic hysteresis in the investigated materials have been established. The small magnetic hysteresis is shown to be caused by the penetration of a magnetic flux into a superconductor and its capture in the region of boundaries between HTS crystallites and by Meissner currents flowing through these boundaries. It has been found that, at a certain magnetic prehistory, the small hysteresis collapses, i.e. its footprints disappear. This has been attributed to the interaction between two superconducting subsystems in the investigated polycrystalline HTS, specifically, the effect of the magnetic moments of HTS crystallites on the effective field in the regions of intercrystalline boundaries. The shape of the small magnetic hysteresis loop has been described within the critical state model. [ABSTRACT FROM AUTHOR]

Barium hexaferrite (BaFe12O19) and Ni–Zn ferrite (Ni0.6Zn0.4Fe2O4) powders were synthesized using the microwave hydrothermal method. Composite samples with varying ratios {x(Ni0.6Zn0.4Fe2O4) + (1 − x) (BaFe12O19)} (where x ranged from 0 to 1.0) were prepared through mechanical mixing. The pure and composite samples were subjected to a 4-h heat treatment at 800 °C. The structural characteristics of the pure samples were analyzed using X-ray diffraction (XRD), revealing the hexagonal structure of BaFe12O19 and the spinel structure of Ni0.6Zn0.4Fe2O4. Morphological properties were investigated using field emission scanning electron microscopy (FESEM). The results confirmed a hexagonal morphology for BaFe12O19, a spherical morphology for Ni0.6Zn0.4Fe2O4, and a mixed morphology for the composites, with grain sizes ranging from 50 to 200 nm. The optical properties were explored through UV–Vis absorption studies, and the optical energy gap values were determined using the Tauc plots. The magnetic behavior of the samples was studied by analyzing magnetic hysteresis loops. Pure samples exhibited a smooth hysteresis behavior, while composite samples displayed a step-like pattern. A possible relation between the magnetic interaction between the two different materials in the composites was investigated. [ABSTRACT FROM AUTHOR]

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Magnetic materials with zero hysteresis are posed to have a significant impact on sustainable energy conversion, electronics, and communication technologies. As the global market for soft magnetic materials continues to expand, driven by increasing demand in renewable energy, automotive, and power transmission sectors, it is important to design magnets that can be cycled under an external field reversibly and rapidly multiple times without a decay in magnetic response. However, designing magnets with small hysteresis has been a challenge because we do not fully understand its origins. In this article, I outline key research efforts investigating the fundamental mechanisms underpinning hysteresis in soft magnets and, highlight recent developments in the use of nonlinear analysis and nucleation barrier methods to predict coercivity in these materials. [ABSTRACT FROM AUTHOR]

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

Cobalt ferrite–silica–gold nanocomposite (CoFe2O4@SiO2@Au) is synthesized using a new method involving: i) the polyol method for cobalt ferrite nanoparticles (CoFe2O4), ii) the Stober method for silica coating, iii) surface functionalization with 3‐aminopropyl triethoxysilane (APTES), and iv) decoration with gold nanoparticles via tetrakis hydroxy‐methyl‐phosphonium (THPC) reduction. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) confirm the morphology of the nanoparticles and coatings for the nanocomposites. Ultraviolet–visible (UV–Vis) absorption spectra exhibit plasmon resonance peaks with tuned shifts, discuss in terms of the difference in dielectric permittivity in the core where gold nanoparticles are anchored. Magnetic hysteresis analysis reveals superparamagnetic behavior with reduced saturation magnetization for the nanocomposites. These findings are useful, as superparamagnetic behavior combined with control of plasmonic emission is highly relevant for several magneto‐plasmonic applications. [ABSTRACT FROM AUTHOR]

In this paper, we studied the spin-3/2 Ising model of diluted graphene-like monolayer under a non-equilibrium state by using Monte Carlo (MC) simulation. We conducted a comprehensive analysis of the temperature-dependent magnetization curves, susceptibility, critical temperature, and hysteresis loops taking into account various factors such as the anisotropy, exchange coupling, external magnetic field, and shell atom concentration. We also compared our findings to various existing theoretical works and obtained a strong quantitative alignment with certain theoretical predictions and experimental outcomes. [ABSTRACT FROM AUTHOR]

The influence of size on the dynamic magnetic hysteresis properties and dynamic phase transitions of Fe and F e 3 O 4 2D-circular nanodisks with varying diameters has been explored in the micromagnetic framework. This investigation is conducted under a sinusoidal dynamic magnetic field along the x-direction by solving the Landau-Lifshitz-Gilbert (LLG) equation with the OOMMF software at zero temperature. The dynamic hysteresis of nanodisks is profoundly impacted by both the frequency and amplitude of the applied external field, along with the particle size. As particle size decreases, there is an observed increase in the frequency values at which the transition to dynamic ordered frequency occurs in Fe nanodisks, whereas a decrease is noted in the transition frequency values of F e 3 O 4 nanodisks. [ABSTRACT FROM AUTHOR]

Formation of carbonates involve an interplay of processes, including climate, ocean circulation, marine organisms, sediment sources, transport, deposition and diagenesis. The Yucatan peninsula is characterized by a thick carbonate sequence, which has been studied by geological-geophysical surveys and drilling. Characterizing carbonate systems remains an important yet complex undertaking. Here, results of a magnetic susceptibility and X-ray fluorescence geochemical study are used to characterize the Paleogene carbonate sequence in the Tekax borehole of the Chicxulub Drilling Program. The carbonate sequence is ~222 m thick, formed by limestones, dolomites, carbonate breccias and evaporites. Changes in Si, Ca, Fe, Mg, Al, Ti and magnetic susceptibility correlate with lithology downcore. The Ca contents vary through the sequence with a trend around 24% and low discrete values. The upper unit shows higher Ca contents. The Si contents vary downhole, between about 0.03 to 38 %. The carbonates show weak magnetic susceptibilities associated with diamagnetic and paramagnetic minerals, characteristic of carbonate sediments and reduced terrigenous input. Magnetic hysteresis shows fine grained low coercivity magnetite and titanomagnetites, with PSD and MD domain states. Six units are identified through the lithological column. The carbonate sequence shows effects of varying dissolution, fracturing and dolomitization. The lower carbonate unit above the breccia contact shows evaporites, with gypsum and anhydrites. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) actuators represent an important class of semi-active devices that have received extensive investigation and deployment in the field of vibration reduction systems. Their notable features include a significant reduction in energy consumption, along with an impressive tunable range of continuously controllable damping forces. The force output of these devices is a complex function that involves two hysteretic mechanisms: magnetic and mechanical (i.e. hydraulic). While the total hysteresis mechanism of these devices has been the subject of considerable study, comparatively little attention has been paid to their magnetic hysteretic behavior. In this study, the authors examine the behavior of the dual coil MR actuator's control circuit and attempt to extract the magnetic flux information from the laboratory measurements of electrical signals applied to it. The study is further enhanced by the incorporation of the Bouc-Wen (B-W) hysteretic unit, which serves to replicate the flux-current (or magnetic) hysteretic relationship. The B-W model's parameters are identified through the use of a hybrid algorithm, namely the particle swarm optimization and fmincon hybrid optimizing strategy. It incorporates the advantages of both algorithms, resulting in an average improvement of 0.38% in standard deviation compared to fmincon, across 1A to 5A, when comparing the experimental and simulation data. This strategy is employed to fit the model predictions to the flux data, derived from the reconstructed flux and current in time histories. The findings of the study demonstrate that the B-W model is an effective tool for predicting the variation in magnetic flux in response to an exciting current. The results can be implemented for prototyping or validating a model-based controller for MR actuator systems. [ABSTRACT FROM AUTHOR]

This paper explores the effects and impacts of the metallurgical process of quenching on grain-oriented strips of electrical steel. Experimental findings reveal that quenching resulted in increased hardness and an increased Young's modulus. An analysis of the material structure post-quenching indicates significant alterations in grain spacing and reduced height differences between grains. However, the magnetic properties of the steel deteriorated following quenching. [ABSTRACT FROM AUTHOR]

Abstract After the publication of “Direct formation of hard‐magnetic tetrataenite in bulk alloy castings” Ivanov et al., Advanced Science 10 (2022) 2204315, the authors identified a potential misinterpretation of the experimental data. Further work confirms that the original conclusions cannot be supported, and accordingly the paper is retracted. X‐ray diffraction shows the presence of (Fe,Ni)3P, giving additional Bragg peaks that were previously attributed to tetrataenite. Extra Bragg reflections observed in transmission electron diffraction, and earlier considered to be superlattice reflections from tetrataenite, instead result from oxidation of the sample surface during preparation. Measurements of magnetic hysteresis show no regions of high coercivity of the kind expected when tetrataenite is present. It is concluded that as‐cast bulk samples of Fe‐Ni‐P‐(C) show no evidence of tetrataenite on any length scale. Nevertheless, the addition of phosphorus should remain of interest in ongoing efforts to manufacture tetrataenite.

We present an introductory review of concepts behind micromagnetic simulations, in which magnetic moments representing collections of atomic spins within a material evolve according to the Landau-Lifshitz-Gilbert equation, a generalized torque equation. This evolution is determined by a variety of interactions, including those arising from external fields, magnetostatic and exchange effects, and magnetic anisotropy. Anisotropy is a key ingredient in the Stoner-Wohlfarth model, which provides a quantitative basis for understanding magnetic hysteresis. In turn, hysteresis loops provide a basis for comparing simulations and experiments, and are important, for example, in quantifying the heating response of a sample to an oscillating external magnetic field. Micromagnetic simulations bear conceptual similarity to molecular dynamics (MD) simulations, but whereas in MD classical potentials are used to naturally model interactions between atoms and/or molecules, the choice of modelling length scale in micromagnetics is less obvious. If effective interactions are determined for, say, two crystallographic unit cells of a material, how interaction parameters should scale with micromagnetic simulation cell size, particularly at finite temperature, is still an area of research. Finally, we discuss the coupling of magnetic and mechanical degrees of freedom in simulating atomic and nanoparticle systems. This review is based, in part, on our own experience in modelling hysteretic heating of magnetite nanoparticles.

NiCo2O4 (NCO) films grown on MgAl2O4 (001) substrates have been studied using magnetometry and x-ray magnetic circular dichroism based on x-ray absorption spectroscopy and spin-polarized inverse photoemission spectroscopy with various thicknesses down to 1.6 nm. The magnetic behavior can be understood in terms of a layer of optimal NCO and an interfacial layer (1.2 ± 0.1 nm), with a small canting of magnetization at the surface. The thickness dependence of the optimal layer can be described by the finite-scaling theory with a critical exponent consistent with the high perpendicular magnetic anisotropy. The interfacial layer couples antiferromagnetically to the optimal layer, generating exchange-spring styled magnetic hysteresis in the thinnest films. The non-optimal and measurement-speed-dependent magnetic properties of the interfacial layer suggest substantial interfacial diffusion. [ABSTRACT FROM AUTHOR]

The Stoner–Wohlfarth model is a classical model for magnetic hysteresis of single-domain magnets. For two-dimensional (2D) magnets at finite temperatures, the Stoner–Wohlfarth model must be extended to include intrinsic strong spin fluctuations. We predict several fundamentally different hysteresis properties between 2D and 3D magnets. The magnetization switching diagram known as the astroid figure in the conventional Stoner–Wohlfarth model becomes highly temperature dependent and asymmetric with respect to the transverse and longitudinal magnetic fields. Our results provide new insights into the spintronics applications based on 2D magnetic materials. [ABSTRACT FROM AUTHOR]

Single-phase nanoparticles sample of Y2FeCrO6 double perovskite with an average particle size of 67 nm was prepared and its structural and magnetic behavior is reported. Magnetization vs temperature (M–T) study revealed that the Neel temperature, TN is 327 K, which is greater than the previous finding [Maiti et al., J. Phys. D: Appl. Phys. 46, 415303 (2013)]. Super-exchange interactions in Cr3+–O–Cr3+ and Fe3+–O–Fe3+ networks are responsible for AFM transition. Magnetization reversal (MR) with a high compensation temperature Tcomp = 192 K and sign reversal in both spontaneous and conventional exchange bias fields are observed. In addition, a spin reorientation is observed at TSR ∼ 30 K. At 5 K, a zero-field cooled spontaneous exchange bias (SEB) field of 265 Oe is observed. At the same temperature, after field cooling the sample at 0.5 T, the maximum value of the exchange bias field (CEB) is found to be 2.1 kOe. The SEB shows a sign reversal across TSR, and the CEB reverses its sign across Tcomp. The observed thermal hysteresis of magnetization indicates a first-order phase transition. The loop width of magnetic hysteresis as a function of magnetization exhibits a double peak confirming the multiple magnetic phase behavior. Bipolar switching of magnetization has been demonstrated at 50 K. The competition between single-ion anisotropy and Dzyaloshinsky–Moriya interaction is responsible for the above behaviors. [ABSTRACT FROM AUTHOR]

This research article reports the synthesis of polycrystalline cadmium manganese telluride (Cd1−xMnxTe, CMT with x = 0.08 & 0.12) using a homemade horizontal furnace and studies the influence of Mn concentration on the structure, optical, dielectric and magnetic properties of the polycrystalline material. The phase formation and structure were confirmed by powder X-ray diffraction. The optical characteristics were examined using UV-visible–NIR spectroscopy, which revealed a blueshift in cutoff wavelength (λco) and an increase in bandgap with the increase in Mn concentration. The material showed low absorption coefficients, beneficial for optical isolator applications, enabling efficient light transmission with minimal loss. The photoconductivity analysis indicated negative photoconductivity, demonstrating the material's potential for photodetector applications. Additionally, the resistivity of CMT polycrystals was found to be in the order of 107 to 108 Ω cm. The dielectric constant, dielectric loss and dielectric impedance for the respective ratios were discussed. The saturation magnetization value and magnetic hysteresis loop increase with Mn concentration. [ABSTRACT FROM AUTHOR]

The paper deals with the dynamics of a resistance spot welding system. At the core of this system is a transformer, which is powered on the primary side by a pulse-width modulated inverter and has a full-wave output rectifier on the secondary side that provides a direct welding current. The entire system is nonlinear, due to magnetic hysteresis and electronics. The electronics prevent the current from flowing in all parts of the welding transformer at separate time intervals during the voltage supply period; therefore, not all the parameters affect the dynamic of currents and voltages all the time so the system is also time-variant. To design a high-performance welding system and to predict the maximum possible welding current at a specific load, it is necessary to know the welding and primary currents. The leakage inductances of the system can reduce the maximum welding current significantly at higher frequencies and the same load. There are several methods to determine these currents, each with its drawbacks. Measurements are time-consuming, using professional software is expensive and requires time to learn and free open-source software has many limitations and does not guarantee the correctness of the results. The article presents a new, fourth option—a theoretical derivation of analytical expressions that facilitate straightforward and rapid calculation of the welding and primary currents of the resistance spot welding system with symmetrical secondary branches. The derivation of the mathematical expressions is based on the equivalent circuits that describe the system in different operating states. The results of the numerical simulations confirmed the derived expressions completely. [ABSTRACT FROM AUTHOR]

Soft magnetic composite cores were produced by spark plasma sintering (SPS) from Ni3Fe@ZnFe2O4 and NiFeMo@ZnFe2O4 pseudo-core-shell powders. In the Fe-Ni alloys@ZnFe2O4 pseudo-core-shell composite powders, the core is a large nanocrystalline Permalloy or Supermalloy particle obtained by mechanical alloying, and the shell is a pseudo continuous layer of Zn ferrite particles. The pseudo-core-shell powders have been compacted by SPS at temperatures between 500–700 °C, with a holding time of 0 min. Several techniques were used for the characterisation of the powders and sintered compacts: X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, magnetic hysteresis measurements (DC and AC), and electrical resistivity. The electrical resistivity is stabilised at values of about 7 × 10−3 Ω·m for sintering temperatures between 600–700 °C and this value is three orders of magnitude higher than the electrical resistivity of sintered Fe compacts. The best relative initial permeability was obtained for the Supermalloy/ZnFe2O4 composite compacts sintered at 600 °C, which decreases linearly for the entire frequency range studied, from around 95 to 50. At a frequency of 2000 Hz, the power losses are smaller than 1.5 W/kg. At a frequency of 10 kHz, the power losses are larger, but they remain at a reduced level. In the case of Supermalloy/ZnFe2O4 composite compact SPS-ed at 700 °C, the specific power losses are even lower than 5 W/kg. The power losses' decomposition proved that intra-particle losses are the main type of losses. [ABSTRACT FROM AUTHOR]

The effects of 180, 210, and 230°C reaction temperatures on the structural and magnetic properties of synthesized iron sulfide nanoparticles were studied. The Rietveld refinement analysis result of the X‐ray diffraction data indicated that greigite was the dominant phase in all samples. The sample was prepared at 210°C for 18 h and had a greater wt% ratio of the greigite phase. The crystallite and particle sizes increased with increasing reaction temperatures. Scanning electron microscope images confirmed the presence of aggregation of synthesized rod‐shaped nanoparticles. The magnetic hysteresis curves of all samples showed ferromagnetic behavior at room temperature. The magnetic saturation of three samples increases with increased reaction temperature, but the coercive force has the opposite behavior. Antioxidant activity and cytotoxicity of the sample synthesized at 210°C were investigated. This sample killed cancer cells at relatively moderate and high concentrations with high viability of normal cells, demonstrating the sample's suitability for use in killing cancer cells while avoiding normal cells. [ABSTRACT FROM AUTHOR]

Proportional pressure-reducing valve (PPRV) is widely used in brake circuits and pilot supply lines for directional control valves. The performance of PPRV can be degraded because of the effect of magnetic hysteresis, frictions, and other disturbances, which worsens the accuracy of the entire hydraulic system. This paper presents a high-performance pressure controller of a PPRV considering the model nonlinearities. A nonlinear phenomenological model based on the Hammerstein modeling method is first developed to describe the dynamics of a PPRV. A pressure-dependent damping ratio is carried out to handle the asymmetric nonlinearity at the starting process of pressure adjustments, and a series of experiments are conducted to verify the effectiveness of the model. A second-order adaptive robust controller is developed based on the Lyapunov theorem to guarantee the tracking performance in the presence of parameter uncertainties and uncertain nonlinearities. Comparative experiments show that the proposed second-order adaptive robust control algorithm together with the phenomenological model achieves a significant reduction in pressure-tracking error, compared with the one without the proposed plant model, or other existing controllers such as the feedforward proportional–integral–derivative (PID) controller and the first-order adaptive robust controller. [ABSTRACT FROM AUTHOR]

In this work, we study the magnetocaloric properties of half 5/2 and integer 3 mixed spin model on a square–hexagon «4-6» structures are studied by Monte Carlo simulations. The total magnetization and the magnetization of each sub-lattice of the mixed-spin lattice have been analyzed. The magnetic susceptibility, dM/dT and magnetic entropy changes are found. The magnetic hysteresis cycles under, with the temperatures, exchange interactions (S-S), (σ-σ) and (σ-S), and the crystal fields (Dσ and DS) has been discussed. [ABSTRACT FROM AUTHOR]

The molecular self‐assembly and the magnetic properties of two cyclooctatetraenide (COT)‐based single‐ion magnets (SIM) adsorbed on Ag(100) in the sub‐monolayer (ML) range are reported. Our study combines scanning‐tunneling microscopy, X‐ray photoemission spectroscopy and polarized X‐ray absorption spectroscopy to show that Cp*ErCOT (Cp* = 1,2,3,4,5‐pentamethylcyclopentadienide anion) SIMs self‐assemble as alternating compact parallel rows including standing‐up and lying‐down conformations, following the main crystallographic directions of the substrate. Conversely, K[Er(COT)2], obtained from subliming the [K(18‐c‐6)][Er(COT)2]·2THF salt, forms uniaxially ordered domains with the (COT)2− rings perpendicular to the substrate plane. The polarization‐dependent X‐ray absorption spectra reproduced by the multiX simulations suggest that the strong in‐plane magnetic anisotropy of K[Er(COT)2]/Ag(100) and the weak out‐of‐plane anisotropy of Cp*ErCOT/Ag(100) can be attributed to the strikingly different surface ordering of these two complexes. Compared to the bulk phase, surface‐supported K[Er(COT)2] exhibits a similarly large hysteresis opening, while the Cp*ErCOT shows a rather small opening. This result reveals that despite structural similarities, the two organometallic SMMs have strongly different magnetic properties when adsorbed on the metal substrate, attributed to the different orientations and the resulting interactions of the ligand rings with the surface. [ABSTRACT FROM AUTHOR]

The impact of film thickness and annealing temperature on the structural, electrical, magnetic, and mechanical properties of cobalt–iron–dysprosium (Co40Fe40Dy20) thin films deposited on Si(100) substrates have been investigated. X-ray diffraction (XRD) analysis confirmed the film's crystalline microstructure, featuring dysprosium oxide, Dy2O3(440), and cobalt oxide, Co2O3(422) and Co2O3(511), crystallographic phases. Surface energy measurements indicated a noticeable reduction in surface energy following annealing treatments, which could be ascribed to the alleviation of residual stress and enhanced atomic arrangement, resulting in a more stable film structure with reduced surface energy. The film exhibited a decreasing trend in hardness with increasing thickness, and film resistivity was significantly responsive to alterations in thickness and annealing temperature. Notably, the Co40Fe40Dy20 film demonstrated exceptional characteristics, featuring a high saturation magnetization (Ms) of 675 emu/cm3 and a low coercivity (Hc) of 9.5 Oe. Further analysis of magnetic domains and hysteresis loops revealed that larger and brighter domains were associated with higher Hc. To sum up, the surface roughness of CoFeDy films under various annealing temperatures played a pivotal role in shaping their magnetic, electrical, adhesive, and optical characteristics. An improved low-frequency alternating current magnetic susceptibility (χac) value was achieved by minimizing the pinning effect on domain walls through surface smoothing. Moreover, smoother surfaces displayed heightened carrier conductivity, resulting in a decrease in electrical resistance. On the whole, Co40Fe40Dy20 films exhibited outstanding soft magnetic properties, encompassing high saturation magnetization, low coercivity, exceptional mechanical attributes, and decreased surface energy. [ABSTRACT FROM AUTHOR]

Magnetic hysteresis measurements are routinely made in the Earth and planetary sciences to identify geologically meaningful magnetic recorders, and to study variations in present and past environments. Interpreting magnetic hysteresis data in terms of domain state and paleomagnetic stability are major motivations behind undertaking these measurements, but the interpretations remain fraught with challenges and ambiguities. To shed new light on these ambiguities, we have undertaken a systematic micromagnetic study to quantify the magnetic hysteresis behavior of room‐temperature magnetite as a function of particle size (45–195 nm; equivalent spherical volume diameter) and shape (oblate, prolate and equant); our models span uniformly magnetized single domain (SD) to non‐uniformly magnetized single vortex (SV) states. Within our models the reduced magnetization associated with SV particles marks a clear boundary between SD (≥0.5) and SV (<0.5) magnetite. We further identify particle sizes and shapes with unexpectedly low coercivity and coercivity of remanence. These low coercivity regions correspond to magnetite particles that typically have multiple possible magnetic domain state configurations, which have been previously linked to a zone of unstable magnetic recorders. Of all the hysteresis parameters investigated, transient hysteresis is most sensitive to particles that exhibit such domain state multiplicity. When experimental transient hysteresis is compared to paleointensity behavior, we show that increasing transience corresponds to more curved Arai plots and less accurate paleointensity results. We therefore strongly suggest that transient behavior should be more routinely measured during rock magnetic investigations. Plain Language Summary: Characterizing the magnetic properties and behavior of natural materials in the Earth and planetary sciences is key to identifying reliable magnetic recorders and variations in the environment. One standard method for achieving this is through room‐temperature measurements of magnetic hysteresis. However, the interpretation of magnetic hysteresis data remains one of the most challenging aspects of rock magnetism. To improve our understanding of magnetic hysteresis data, we have systematically investigated how the hysteresis properties of distributions of randomly oriented magnetite change as a function of particle size and shape and how this can help us quantify the contents of natural materials and identify rocks that may give unreliable magnetic signals. We model prolate, oblate and equant magnetite particles in the size range 45–195 nm. We show that magnetic hysteresis defines a clear boundary between simple uniform magnetic structures and more complex non‐uniform magnetic structures. We also identify the sizes and morphologies of magnetic particles that are likely to have unstable remanent magnetizations. These unstable particles are associated with distinctive hysteresis behavior, suggesting that hysteresis data can be used to identify rock samples dominated by such behavior. Key Points: Magnetic hysteresis is micromagnetically modeled for oblate, prolate and equant magnetite particles (45–195 nm)Hysteresis loop shape is highly dependent on particle size/shape due to complex switching behavior of single vortex statesTransient magnetic hysteresis is a powerful tool for identifying stable remanent magnetizations but is currently infrequently reported [ABSTRACT FROM AUTHOR]

The ability of rocks to hold a reliable record of the ancient geomagnetic field depends on the structure and stability of magnetic domain‐states contained within constituent particles. In paleomagnetic studies, the Day plot is an easily constructed graph of magnetic hysteresis parameters that is frequently used to estimate the likely magnetic recording stability of samples. Often samples plot in the region of the Day plot attributed to so‐called pseudo‐single‐domain particles with little understanding of the implications for domain‐states or recording fidelity. Here we use micromagnetic models to explore the hysteresis parameters of magnetite particles with idealized prolate and oblate truncated‐octahedral geometries containing single domain (SD), single‐vortex and occasionally multi‐vortex states. We show that these domain states exhibit a well‐defined trend in the Day plot that extends from the SD region well into the multi‐domain region, all of which are likely to be stable remanence carriers. We suggest that although the interpretation of the Day plot and its variants might be subject to ambiguities, if the magnetic mineralogy is known, it can still provide some useful insights about paleomagnetic specimens' dominant domain state, average particle sizes and, consequently, their paleomagnetic stability. Plain Language Summary: Ancient magnetic field recordings from rocks, provide information about the early habitability of Earth and formation of the Solar System. Key to understanding the reliability of these magnetic recordings is knowing the particle size and shape of a rock's constituent magnetic minerals. Small magnetite particles (⪅100 nm) are magnetically uniform, but as particle size increases the magnetic structures become non‐uniform and increasingly complex. These different types of structures are termed domain states, and yield different magnetic hysteresis responses, often summarized on a so‐called "Day" diagram—a commonly used diagnostic of domain state (or particle size). The position of particles in the size 100–1,000 nm on the Day plot is poorly quantified. This is a problem, as it has been shown in the last 5 years, that this particle size range carries the most stable magnetic recordings, lasting potentially longer than the age of the universe. These particles contain vortex‐like magnetic structures. Using a numerical micromagnetic algorithm, this is the first comprehensive study to quantify the magnetic response of vortex structures on the Day plot. We show that careful use of the Day plot can provide insight into the ability of a sample to retain recordings of the ancient geomagnetic field. Key Points: Vortex domain states for magnetite predominantly have pseudo‐single‐domain Day plot characteristicsIf the mineralogy is known, the Day plot can provide an estimate on the dominance of stable remanence carriers [ABSTRACT FROM AUTHOR]

Yttrium (1 mol %) -doped 0.49BiFeO3-0.20Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 ceramic at the morphotropic phase boundary was synthesized by a solid-state reaction via columbite precursor technique. X-ray diffraction (XRD) and FESEM analysis confirmed a perovskite phase in the P1m1 space group with a homogeneous microstructure sintered at 920 °C. Rietveld refinement yield lattice parameters a = 3.95984 Å, b = 3.93828 Å, c = 4.04466 Å, α = 90.000°, β = 89.970°, γ = 90.000°. Studies of dielectric permittivity and ferroelectric hysteresis at room temperature shows Y doping impact, exhibiting low dielectric loss and a saturated hysteresis loop. The synthesized sample remains fatigue-free over 104 cycles, with a high value of converse piezoelectric coefficient of d33* ̴ 723 pm/V. Weak ferromagnetism is observed in the magnetic hysteresis loop (M-H) at room temperature, suggesting potential applications in ferroelectric-based technologies. [ABSTRACT FROM AUTHOR]

In view of tuning different transitions, Co and V are substituted in Mn-rich Ni-Mn-Ga alloy. Ni41Co9Mn30V2Ga18 sample undergoes a coupled magnetostructural transition above room temperature with a low thermal and magnetic hysteresis and high sensitivity of martensite transition temperature (8 K/T) with the field. ∆SM is found to be a maximum of −2.33 J/kg-K for 3 T field change with a large RCP of 158 J/kg. The presence of intermartensite transition along with the magnetostructural transition widens the range of working temperature. [ABSTRACT FROM AUTHOR]

Various experimental methods are used to examine the effect of cooling rate on the magnetic properties of magnetic materials, such as melt spinning at different wheel speeds. To shed light on these experimental studies as a theoretical study, we used a mixed spin (1, 3/2) Ising system on a square lattice under an oscillating magnetic field within the path probability method. It is very advantageous to use the path probability method in such studies, because it explains the dynamic magnetic phase behaviors and dynamic hysteresis curves of the system depending on all system parameters, and one of the coupling parameters ( k 2 ) arising in this method corresponds to the wheel speed (rate constant) in the melt spinning method. In this study, dynamic hysteresis curves of a magnetic material were obtained for different k 2 parameters as well as other system parameters, namely reduced temperature, crystal field interaction, and angular frequency. In some magnetic materials, hard and soft magnetic hysteresis loop behaviors and single and multiple hysteresis loop behaviors have been obtained, which have been reported theoretically as well as experimentally. The results shed light on experimental workers who were unable to reach higher wheel speeds using the melt-spinning method. [ABSTRACT FROM AUTHOR]

The inorganic multiferroic compounds Bi0.9Sm0.1Fe1 − xVxO3 (x = 0.0, 0.015, 0.03, and 0.045) were prepared by the solid-state reaction method. X-ray diffraction analysis confirmed the rhombohedral perovskite-like structure with minor traces of the impurity phases Bi2Fe4O9 and Bi25FeO40. The lattice parameters a and c, and the volume of the hexagonal unit cell were extracted from the X-ray diffraction data and found to increase as the V5+ content is increased. The average crystallite size was estimated to be in the range 380–415 Å. Fourier transform infrared spectroscopy confirmed the rhombohedral perovskite-like structure via the vibration bands of the octahedral FeO6 group observed between 410 and 570 cm−1. A differential scanning calorimeter was used to record the thermal scans which revealed that the compounds have undergone crystalline phase transitions at temperatures in the range 300–320°C. A 4.5% V + 5 substitution has shifted the transition peak by 20°C. The magnetic hysteresis loops taken at room temperature with a vibrating sample magnetometer revealed the ordinary ferromagnetic behavior. The V5+ substitution enhanced the remanent magnetization, but the magnetic coercivity was found to fluctuate around an average value of about 1000 Oe. The compound Bi0.9Sm0.1Fe0.955V0.045O3 exhibited the maximum remanent magnetization. [ABSTRACT FROM AUTHOR]

In this work, the effect of the action of gamma quanta and neutrons on the magnetic properties of Ta/feromagnet/IrMn/Ta bilayer films with an exchange bias of the hysteresis loop is studied. The samples were fabricated by magnetron sputtering, and their structure was studied by small-angle X-ray reflectometry and X-ray diffractometry. The measurement of the magnetic hysteresis loops of the irradiated and non-irradiated samples was carried out by the methods of magneto-optical Kerr magnetometry. As a result, the effect of broadening of the magnetic hysteresis loop after irradiation was found. The maximum broadening of the hysteresis loop was observed in the NiFe/IrMn film under neutron irradiation; in this case, the loop width increased by more than 2.5 times. No noticeable change in the field of the exchange bias of the hysteresis loops was observed in the entire range of radiation exposure. [ABSTRACT FROM AUTHOR]

Co-precipitation method was used to fabricate Zr-Al substituted M-Type barium hexagonal ferrite with a unique composition Ba1-xZr0.5x Al0.3 Fe11.7 O19 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). The materials were characterized using Fourier Transform Infrared spectroscopy and a magnetic hysteresis loop. For each sample, the values of Ms, Hc, Mr, remanence ratios (Mr/Ms), and magneton number (nB) are determined using M-H loops. The Mr/Ms ratio of the synthesized hexaferrites particles is between 0.001017 and 0.143103, indicating a single magnetic domain. FTIR spectroscopy was used to study the inter-atomic forces and gives information about the absorption and emission spectrum for solids, liquids and gases. The results indicate that the synthesized compounds may have potential use as perpendicular magnetic recording media due to the growing trend in saturation magnetization, remanence, and coercivity. [ABSTRACT FROM AUTHOR]

Micromagnetic modeling allows the systematic study of the effects of particle size and shape on the first‐order reversal curve (FORC) magnetic hysteresis response for magnetite particles in the single‐domain (SD) and pseudo‐single domain (PSD) particle size range. The interpretation of FORCs, though widely used, has been highly subjective. Here, we use micromagnetics to model randomly oriented distributions of particles to allow more physically meaningful interpretations. We show that one commonly found type of PSD particle—namely the single vortex (SV) particle—has far more complex signals than SD particles, with multiple peaks and troughs in the FORC distribution, where the peaks have higher switching fields for larger SV particles. Particles in the SD to SV transition zone have the lowest switching fields. Symmetrical and prolate particles display similar behavior, with distinctive peaks forming near the vertical axis of the FORC diagram. In contrast, highly oblate particles produce "butterfly" structures, suggesting that these are potentially diagnostic of particle morphology. We also consider FORC diagrams for distributions of particle sizes and shapes and produce an online application that users can use to build their own FORC distributions. There is good agreement between the model predictions for distributions of particle sizes and shapes, and the published experimental literature. Plain Language Summary: In Earth, planetary and environmental sciences, magnetic methods are often used to rapidly measure the properties of rocks, sediments, meteorites, and soils. These magnetic properties can be proxies for environmental change or indicators of magnetic recording fidelity. The magnetic properties are dependent on the magnetic mineralogy and particle size and shape of the minerals within a sample. There is no single measurement that provides a unique interpretation; instead, a range of methods are applied, one of which is magnetic hysteresis analysis. First‐order reversal curves (FORCs) are an advanced type of hysteresis analysis, and the FORC response of a mineral depends on magnetic domain state, which is strongly controlled by both the size and shape of a particle. We understand the FORC response of very big (> ${ >} $1,000 nm) and very small particles (< ${< } $100 nm), but interpretation for particles in between, the so called pseudo‐single domain (PSD) state, has remained elusive. This is a problem as the magnetic signature of many rocks is dominated by PSD signals. In this paper we use numerical micromagnetic modeling to systematically study the effect of particle size and shape on particles that support a particular type of PSD FORC response—the single‐vortex. Key Points: We have modeled first‐order reversal curve (FORC) diagrams for single‐domain and single‐vortex sized magnetite for a range of particle sizes and morphologiesSingle‐vortex particles display complex structures in the FORC distribution with multiple peaks and troughsThe main peaks of the single‐vortex FORC distributions have higher coercivities than the single‐domain peak [ABSTRACT FROM AUTHOR]

Recently, we [J. Magn. Magn. Mater. 514 (2020) 167242] presented a study of the dynamic magnetic loop features of molecular-based magnetic materials and ferrimagnetism that were investigated by using a mixed spin 1/2 and spin-1 ferrimagnetic Ising system within the path probability method. We found several interesting dynamic magnetic hysteresis properties and observed that the obtained results are in qualitatively good agreement with some theoretical and experimental studies in magnetic materials. We extended our recent previous published work to study the dynamic magnetic hysteresis properties of molecular-based magnetic materials and ferrimagnetism utilizing the mixed spin (2, 5/2) ferrimagnetic Ising system on a hexagonal lattice employing the path probability method. The spin (2, 5/2) Ising system is one of the most suitable and most used prototypical systems to investigate many molecular-based magnetic materials and ferrimagnetic materials. We found more interesting dynamic magnetic hysteresis properties such as double, triple, quadruple and quintuple loop behaviors for the layer magnetization, and only double and triple loops for the total magnetization. We found that some of our obtained results are in qualitatively good agreement with some theoretical, experimental reported works, and the works on some magnetic materials as obtained by the melt-spinning technique. [ABSTRACT FROM AUTHOR]

Cerium doped cobalt ferrite nanoparticles with chemical formula CoFe 1·9 Ce 0·1 O 4 were synthesized at different annealing temperatures (600, 700, 800, 900 and 1000C°) via sol-gel auto-combustion method. Thermal analysis for sample annealed at 1000C° was examined through differential scanning calorimetry (DSC) and revealed the presence of exothermic peak at around 500C° attributed to crystallization of prepared nanoferrites. Structural analysis such as phase formation, crystallinity and morphology was investigated by x-ray powder diffraction (XRD) and high resolution transmission electron microscope (HRTEM). XRD study revealed higher dependence of grain size growth with annealing temperatures as compared to lattice parameter. HRTEM investigation confirmed that grains have almost uniform morphology with some agglomeration and confirmed values of lattice parameters and grain sizes calculated from XRD data. Magnetic hysteresis was studied by vibrating sample magnetometer (VSM) at room temperature with an applied field of 20 kOe. The results showed an increase in saturation magnetization and remanent magnetization with increasing of annealing temperature, whereas a decline in coercivity was observed. Distribution of cations at tetrahedral and octahedral sites was investigated using x-ray and magnetic parameters which confirmed the mixed spinel ferrite nature of samples. Dielectric properties were carried out at room temperature in the range 0.1Hz–3.0 MHz. Both dielectric constant and ac conductivity decreased with rising of annealing temperature. Variation of dielectric loss tangent, impedance, electric modulus and relaxation time with temperature were also investigated. The effect of annealing temperature on the structure and its impact on magnetic and dielectric properties has been examined and discussed. [ABSTRACT FROM AUTHOR]

Valence tautomeric complexes (VT) are promising systems for creating molecular devices. From this viewpoint, valence tautomeric complexes with a hysteresis loop on the magnetic curve are of special interest as potential memory elements. The hysteresis loop is a consequence of retarded structural rearrangements which investigation is an actual problem. Recently, we have described a new VT transition taking place in a bis-dioxolene cobalt complex with imino-pyridine having a TEMPO substituent (A. A. Zolotukhin, et al., Inorg. Chem., 2017, 56, 14751-14754). Valence tautomeric transformation occurs with a hysteresis loop and is accompanied by a phase transition. The phase transition taking place during cooling is accompanied by crystal destruction. This fact makes it impossible to monitor the structural changes responsible for the hysteresis loop. The current research attempts to resolve this problem. A nickel compound of the same composition (TEMPO-imino-pyridine)Ni(3,6-DBSQ)2 was synthesized and characterized. It was established to be isostructural with the cobalt complex. It was used as an inert matrix for the dilution of the VT cobalt complex. The number of solid solutions with Co/Ni ratios of 1: 1, 1: 2, 1: 4, and 1: 8 was obtained. Variable temperature magnetic susceptibility measurements show that VT transformation with a hysteresis loop takes place in all solid solutions. The hysteresis loop is shifted to low temperatures primarily due to the shifting of its low-temperature boundary with dilution. The hysteresis width does not change significantly with dilution. DSC detected that transformations are accompanied by phase transitions at different temperatures at cooling and heating. The phase transition at the first cooling occurs at slightly lower temperatures compared with subsequent cycles. These temperatures correspond to the transition temperatures detected from the magnetic curves. The phase transition during the first cooling is accompanied by crystal destruction. Physical destruction takes place in the crystals of all solid solutions. X-ray diffraction powder patterns confirm that phase transition is accompanied by considerable reorganization of the crystal structure typical for the first order transitions. The unit cell volume of solid solutions is larger than that of pure complexes. Especially calculated crystal invariom indicated that the "lattice energy" in a solid solution is the lowest compared with that in "pure" nickel and cobalt complexes. [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]

We investigated the debonding on-demand (DoD) of adhesively bonded hybrid dissimilar joints by applying electromagnetic induction heating to the joint overlap section, wherein the epoxy resin is reinforced with iron oxide (Fe3O4) particles. Ti-6Al-4 V adherends were bonded with CFRP or GFRP adherends using neat/modified epoxy adhesive. DoD tests revealed that eddy current heating of Ti-6Al-4 V was a dominant heating mechanism of the joints while both eddy current and magnetic hysteresis of CFRP and Fe3O4 acted as a secondary heating factor. A low content Fe3O4 and thinner composite adherend reduced the time to failure of the joints. Likewise, CFRP required a shorter time for debonding compared to GFRP due to its electromagnetic properties. Modifications with 2 and 5 wt.% Fe3O4 for CFRP and GFRP joints led to 31% and 37% time reduction which will be crucial for energy-saving when debonding large structures. Remarkably, sandblasting improved the electromagnetic induction capabilities of Ti-6Al-4 V, leading to a notable increase in the heating rate, which jumped from around 20°C/s to 80°C/s. Sandblasting enhanced the surface roughness of the adherends but only the water contact angle of GFRP decreased considerably. Fe3O4 modifications increased the epoxy residue on the Ti-6Al-4 V surface from 26% to 99%. DIC revealed the strain distribution of bulk materials to understand the thermomechanical mismatches between the materials and the adhesive joints exhibited high peel stresses at the overlap ends. The low weight content (2 and 5 wt.%) of Fe3O4 exhibited beneficial effects on the mechanical, thermal, thermomechanical, wettability and lap shear strength. [ABSTRACT FROM AUTHOR]

(Fe,Co)2(P,Si) quaternary compounds combine large uniaxial magnetocrystalline anisotropy, significant saturation magnetization and tunable Curie temperature, making them attractive for permanent magnet applications. Single crystals or conventionally prepared bulk polycrystalline (Fe,Co)2(P,Si) samples do not, however, show a significant coercivity. Here, after a ball-milling stage of elemental precursors, we optimize the sintering temperature and duration during the solid-state synthesis of bulk Fe1.85Co0.1P0.8Si0.2 compounds so as to obtain coercivity in bulk samples. We pay special attention to shortening the heat treatment in order to limit grain growth. Powder X-ray diffraction experiments demonstrate that a sintering of a few minutes is sufficient to form the desired Fe2P-type hexagonal structure with limited secondary-phase content (~5 wt.%). Coercivity is achieved in bulk Fe1.85Co0.1P0.8Si0.2 quaternary compounds by shortening the heat treatment. Surprisingly, the largest coercivities are observed in the samples presenting large amounts of secondary-phase content (>5 wt.%). In addition to the shape of the virgin magnetization curve, this may indicate a dominant wall-pining coercivity mechanism. Despite a tenfold improvement of the coercive fields for bulk samples, the achieved performances remain modest (HC ≈ 0.6 kOe at room temperature). These results nonetheless establish a benchmark for future developments of (Fe,Co)2(P,Si) compounds as permanent magnets. [ABSTRACT FROM AUTHOR]

The title radical R⋅, synthesized by reduction of the corresponding cation R+, is thermally stable up to ~380 K in the crystalline state under anaerobic conditions. With SQUID magnetometry, single‐crystal and powder XRD, solid‐state EPR and TG‐DSC, reversible spin‐Peierls transition between diamagnetic and paramagnetic states featuring ~10 K hysteretic loop is observed for R⋅ in the temperature range ~310–325 K; ΔH=~2.03 kJ mol−1 and ΔS=~6.23 J mol−1 K−1. The transition is accompanied by mechanical movement of the crystals, i. e. by thermosalient behavior. The low‐temperature diamagnetic P‐1 polymorph of R⋅ consists of R⋅2 π‐dimers arranged in (...R⋅2...)n π‐stacks; whereas the high‐temperature paramagnetic P21/c polymorph, of uniform (...R⋅...)n π‐stacks. With the XRD geometries, CASSCF and broken‐symmetry DFT jointly suggest strong antiferromagnetic (AF) interactions within R⋅2 and weak between R⋅2 for the (...R⋅2...)n stacks; and moderate AF interactions between R⋅ for the (...R⋅...)n stacks. The fully hydrocarbon archetype of R⋅ does not reveal the aforementioned properties. Thus, the fluorinated 1,3,2‐benzodithiazolyls pave a new pathway in the design and synthesis of metal‐less magnetically‐bistable materials. [ABSTRACT FROM AUTHOR]