Search

Multiferroic materials can realize the mutual coupling between force, electricity, magnetism and other physical fields, and have important application prospects in the field of small size, fast response and low power consumption of magnetoelectric devices. GaFeO3 is a highly promising multiferroic material featuring high spontaneous magnetization and polarization beyond room temperature. In this study, Ferroelectric Mgx Ga1 - x FeO3 (x = 0. 02, 0. 05, 0. 07 and 0. 10) single crystals with a diameter of about 7 mm were grown by light floating zone method. The effect of Mg2 + on the saturation magnetization and magnetic transition temperature of GaFeO3 (GFO) crystals were studied. The structure and phase of the crystal were analyzed through XRD, the results show that all the prepared samples correspond to the diffraction characteristics of the standard crystal card library GFO (PDF#76-1005), and no other heterophase appears. The XRD refinement results indicate that, the crystal structure is orthogonal and its space group is Pna21. As the concentration of Mg2 + rises, the lattice constant and cell volume initially increase and subsequently decrease. Additionlly, the magnetic properties of the crystal were studied through a comprehensive physical property measurement system, the magnetic transition temperature and saturation magnetization of the grown crytals also increase firstly and then decrease with the increase of Mg2 + doping content. When the Mg2 + doping amount is 0. 07, the magnetic transition temperature and saturation magnetization reach the maximum values of 187. 82 K and 8. 75 emu/g, respectively, which achieves the purpose of doping modification. [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]

This article describes the use of Monte Carlo simulations to examine the magnetism of a planar striped Borophene-like nanostructure, which is made up of atoms with spin σ-1. We investigate how changes in the exchange coupling (Jσσ), external magnetic field (H), and crystal field (D) parameters affect the thermal changes in magnetization and susceptibility. We also analyze the changes in the blocking temperature (TB) based on variations in Jσσ, H, and D. Additionally, we discuss the hysteresis cycle and the effects of various physical parameters on the coercive field (Hc). The significant magnetic response of the striped Borophene-like nanostructure has potential applications for a variety of technologies that operate in low-temperature conditions. [ABSTRACT FROM AUTHOR]

The features of switching processes and electromechanical hysteresis in porous piezoceramics in the lead zirconate titanate system were studied in comparison with those in dense piezoceramics of the same composition. It was shown that the differences in switching behavior between the dense and porous piezoceramics are due to micro- and mesostructural features of the porous piezoceramics. [ABSTRACT FROM AUTHOR]

This study presents an analytical model for the drain-induced barrier lowering (DIBL) of a junctionless gateall-around FET with ferroelectric, utilizing a 2D potential model. A multilayer structure of metal-ferroelectric-metalinsulator-semiconductor is used as the gate, as well as the remanent polarization and coercive field values corresponding to HZO are used. The DIBLs obtained with the proposed model demonstrate good agreement with those obtained using the second derivative method, which relies on the 2D relationship between drain current and gate voltage. The results demonstrate that an increase in ferroelectric thickness leads to a negative DIBL value due to the ferroelectric charge. Additionally, there exists an inverse relationship between ferroelectric thickness and channel length to achieve a DIBL value of 0. This condition is satisfied only with the increase of the ferroelectric thickness as the channel radius and insulator thickness increase. The DIBLs increase with higher remanent polarization and lower coercive field, remaining constant when the ratio of remanent polarization and coercive field is maintained. [ABSTRACT FROM AUTHOR]

Poling and structuring of ferroelectric domains form the basis for developing prospective applications using materials from the lithium‐niobate (LN) family. Applications range from second harmonic generation to electro‐optic modulators or surface acoustic wave devices. In the work presented here, hysteresis measurements are used as a standard method to quantitatively determine the poling properties of these ferroelectrics, including their spontaneous polarization Ps as well as their forward and reverse coercive fields Ec,+ and Ec,−. Systematic measurements that depend on parameters such as the ramp rate R of the applied poling voltage and the waiting time twait between domain inversions are investigated and compared between the congruent variants of LN, lithium tantalate (LT), their magnesium‐doped analogues, and stoichiometric LN. For bulk magnesium‐doped LN, for example, it is found that the resulting coercive field strongly depends on the speed of the voltage ramp, with Ec$E_{\text{c}}$ values ranging from 11 to 21 kV mm−1. These investigations are used as fundamental input for poling ferroelectric lithium niobate‐tantalate solids (LNT), a system that offers a high potential for tuning the material parameters beyond what is possible for LN or LT. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of nanosized polymer polyvinylidene fluoride (PVDF) thin ferroelectric films (two-dimensional ferroelectrics) and their composites with graphene layers, using molecular dynamics methods to (1) study and calculate the polarization switching time depending on the electric field and film thickness, (2) study and calculate the polarization switching time depending on changes of the PVDF in PVDF-TrFE film, and (3) study the polarization switching time in PVDF under the influence of graphene layers. All calculations at each MD run step were carried out using the semi-empirical quantum method PM3. A comparison and analysis of the results of these calculations and the kinetics of polarization switching within the framework of the Landau–Ginzburg–Devonshire theory for homogeneous switching in ferroelectric polymer films is carried out. The study of the composite heterostructures of the "graphene-PVDF" type, and calculations of their polarization switching times, are presented. It is shown that replacing PVDF with PVDF-TrFE significantly changes the polarization switching times in these thin polymer films, and that introducing various graphene layers into the PVDF layered structure leads to both an increase and a decrease in the polarization switching time. It is shown that everything here depends on the position and displacement of the coercive field depending on the damping parameters of the system. These phenomena are very important for various ferroelectric coatings. [ABSTRACT FROM AUTHOR]

We have examined the dynamic hysteresis characteristics and phase transition behavior of permalloy nanodisk with three different shapes, which are controlled by a metric order parameter, using the OOMMF micromagnetic simulation program based on the solution of the Landau-Lifshitz-Gilbert equation by finite difference numerical method approach. The hysteresis loop area, remanent magnetization, and coercive field values of the permalloy disk have been obtained as functions of the frequency and amplitude of the external sinusoidal magnetic field. In accordance with the simulation results obtained, a transition from a dynamically disordered phase to a dynamically ordered phase has been observed after a certain frequency value, and the phase transition region moved towards higher frequency values with increasing field amplitude. The triggered dynamical orders in other directions than the field have been observed for different frequency intervals. According to the shape effect of soft magnetic material, permalloy disk on dynamic behavior has been slowly reflected when the shape is concave. [ABSTRACT FROM AUTHOR]

The Fe56.8–72.5Zr5.9–11.6N13.8–31.6O1.2–3.4 films were prepared by magnetron deposition. The metastable structural and phase state, which was formed upon deposition, is represented by either mixed (nanocrystalline αFe(Zr,N) + amorphous) or amorphous structure. During subsequent annealing (300–600°C), it slightly shifts toward the stable state due to partial crystallization of the amorphous phase and precipitation of the secondary phases (Fe4N, Fe3N, and ZrO2). The grain structure of the films (grains 3–12 nm in size) is characterized by thermal stability. The relatively low saturation magnetization Ms (870–1400 G) of the films is explained by the presence of the amorphous phase and αFe(Zr,N) solid solution, which remain in the film structure after annealing at all temperatures. The stochastic domain structure is formed in all films under study due to exchange interaction between grains and clusters in the amorphous structure. The strong dependence of the magnetic structure on the phase state and grain structure of the films is demonstrated. The combination of low local magnetic anisotropy and the highest stochastic domain size predetermines the lowest coercive field of the films, which varies in a range of 1 to 50 Oe. [ABSTRACT FROM AUTHOR]

An analytical SS model is presented to observe the subthreshold swing (SS) of a junctionless gate-all-around (GAA) FET with ferroelectric in this paper. For the gate structure, a multilayer structure of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) was used, and the SS was calculated in $15 \leqslant {P_r} \leqslant 30\,\mu C/c{m^2}$ and $0.8 \leqslant {E_c} \leqslant 1.5\,MV/cm$, which are the ranges of remanent polarization and coercive field suggested in various experiments in the case of HZO as the ferroelectric material. It was found that the SSs from the presented analytical SS model agree well with those derived from the relationship between drain current and gate voltage using a 2D potential distribution in the range of device parameters used for simulation. As a result of analyzing the SS of the junctionless GAA FET with ferroelectric using the analytical SS model presented in this paper, the SS decreased because the voltage across the inner gate decreased when the ferroelectric thickness increased. It was observed that the condition of SS < 60 mV/dec was sufficiently obtained according to changes in device parameters such as channel length, channel radius and ferroelectric thickness, and that the SS maintained a constant value according to the ratio of remanent polarization and coercive field Pr/Ec. As Pr/Ec increases, the SS increases as the ferroelectric capacitance increases. As the channel length becomes smaller, the change in SS according to Pr/Ec is more severe.

Abstract This work revealed the role of altering vanadium (V) content in Mn–Zn ferrites. We used the traditional solid-state reaction method to prepare the $${\mathrm{Mn}}_{0.5}{\mathrm{Zn}}_{0.5}{\mathrm{V}}_{\mathrm{x}}{\mathrm{Fe}}_{2-\mathrm{x}}{\mathrm{O}}_{4}$$ Mn 0.5 Zn 0.5 V x Fe 2 - x O 4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) ferrites. Powder X-ray diffraction was used to analyze the samples’ crystal structures, revealing the prepared sample’s spinal cubic crystal structure. With increasing Vanadium concentration, the lattice constant drops proportionately. We used Debye–Scherrer (D–S), Williamson–Hall (W–H) Plot, Halder–Wagner (H–W) Langford, and Size Strain Plot (SSP) methods to compare different structural properties. We also used the impedance analyzer to investigate the samples’ dielectric characteristics and AC conductivity at room temperature over a frequency range of 1 kHz–100 MHz. The magnetic properties, i.e., Saturation magnetization (Ms), Coercive field (Hc), and Remanent magnetization (Mr), were estimated from the ferromagnetic hysteresis behavior of the samples measured using a vibrating sample magnetometer (VSM). The saturation magnetization was observed to decrease with an increase in V content. The Mr and HC vary non-linearly with V contents. The prepared samples’ initial permeability was tested, and a reasonably constant complex permeability (µ') was recorded over a wide frequency range (~ 1000 Hz).

An analytical SS model is presented to observe the subthreshold swing (SS) of a junctionless gate-all-around (GAA) FET with ferroelectric in this paper. For the gate structure, a multilayer structure of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) was used, and the SS was calculated in 15 ⩽ P r ⩽ 30 μ C / c m 2 and 0.8 ⩽ E c ⩽ 1.5 M V / c m , which are the ranges of remanent polarization and coercive field suggested in various experiments in the case of HZO as the ferroelectric material. It was found that the SSs from the presented analytical SS model agree well with those derived from the relationship between drain current and gate voltage using a 2D potential distribution in the range of device parameters used for simulation. As a result of analyzing the SS of the junctionless GAA FET with ferroelectric using the analytical SS model presented in this paper, the SS decreased because the voltage across the inner gate decreased when the ferroelectric thickness increased. It was observed that the condition of SS < 60 mV/dec was sufficiently obtained according to changes in device parameters such as channel length, channel radius and ferroelectric thickness, and that the SS maintained a constant value according to the ratio of remanent polarization and coercive field P r / E c . As P r / E c increases, the SS increases as the ferroelectric capacitance increases. As the channel length becomes smaller, the change in SS according to P r / E c is more severe. An analytical SS model is presented to observe the subthreshold swing (SS) of a junctionless gate-all-around (GAA) FET with ferroelectric in this paper. For the gate structure, a multilayer structure of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) was used, and the SS was calculated in and , which are the ranges of remanent polarization and coercive field suggested in various experiments in the case of HZO as the ferroelectric material. It was found that the SSs from the presented analytical SS model agree well with those derived from the relationship between drain current and gate voltage using a 2D potential distribution in the range of device parameters used for simulation. As a result of analyzing the SS of the junctionless GAA FET with ferroelectric using the analytical SS model presented in this paper, the SS decreased because the voltage across the inner gate decreased when the ferroelectric thickness increased. It was observed that the condition of SS < 60 mV/dec was sufficiently obtained according to changes in device parameters such as channel length, channel radius and ferroelectric thickness, and that the SS maintained a constant value according to the ratio of remanent polarization and coercive field P r / E c . As P r / E c increases, the SS increases as the ferroelectric capacitance increases. As the channel length becomes smaller, the change in SS according to P r / E c is more severe. [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]

Recently, Kittel’s theory of ferromagnetic domains in thin films in one dimension, i. e. with the domains extended infinitely over one in-plane direction and with the anisotropy axis oriented perpendicular to the film was revisited by considering the film thickness and unbalanced domains with up and down magnetization, yielding to the computation of magnetic hysteresis [C. M. Teodorescu, Res. Phys. 46 (2023) 106287]. In this work, the above study is extended to samples featuring two-dimensional domain landscapes, for materials with strong magnetic anisotropy, typically characterized by a superunitary ratio between the anisotropy energy and the stray field energy densities. This allows one to compute the most stable structures for vanishing average magnetization 〈M〉 together with hysteresis curves for thin films with perpendicular magnetic anisotropy and two-dimensional rectangular domains and also for thin films with in-plane magnetic anisotropy. For two-dimensional films with perpendicular magnetic anisotropy, the most stable structure for 〈M〉 = 0 is found to be that with domains infinitely elongated along one in-plane direction, i. e. the one-dimensional case treated in the preceding work. For thin stripes with in-plane magnetization, the domain size l is approximately linear with the stripe lateral size d for low film thickness, while for large film thicknesses it follows a Kittel-like law, but as function of the stripe size l ∼ d1/2. For in-plane magnetized thin films of infinite lateral extent, the most stable structure is the single domain. As for hysteresis curves, the two-dimensional case with perpendicular magnetic anisotropy is shown to evolve from a 2D landscape derived from the checkerboard structure, but with unbalanced domains for magnetization near saturation, towards one-dimensional domain structures for lower magnetization. In some cases and depending also on the demagnetization factor, the one-dimensional case is not reached, and the film exhibit 2D structures on the whole range of the magnetization curve. The hysteresis obtained for thin magnetic stripes with in-plane magnetization also can exhibit a rich structure, with minor cycles on the wings of the magnetization curves evolving towards „normal” hysteresis (again, depending on the film thickness, stripe lateral size and demagnetization factor). An infinite thin film with in-plane anisotropy features a steplike magnetization dependence on the applied field.

This work revealed the role of altering vanadium (V) content in Mn-Zn ferrites. We used the traditional solid-state reaction method to prepare the Mn0.5Zn0.5VxFe2-xO4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) ferrites. Powder X-ray diffraction was used to analyze the samples' crystal structures, revealing the prepared sample's spinal cubic crystal structure. With increasing Vanadium concentration, the lattice constant drops proportionately. We used Debye-Scherrer (D-S), Williamson-Hall (W-H) Plot, Halder-Wagner (H-W) Langford, and Size Strain Plot (SSP) methods to compare different structural properties. We also used the impedance analyzer to investigate the samples' dielectric characteristics and AC conductivity at room temperature over a frequency range of 1 kHz-100 MHz. The magnetic properties, i.e., Saturation magnetization (Ms), Coercive field (Hc), and Remanent magnetization (Mr), were estimated from the ferromagnetic hysteresis behavior of the samples measured using a vibrating sample magnetometer (VSM). The saturation magnetization was observed to decrease with an increase in V content. The Mrand HC vary non-linearly with V contents. The prepared samples' initial permeability was tested, and a reasonably constant complex permeability (μ') was recorded over a wide frequency range (~ 1000 Hz). [ABSTRACT FROM AUTHOR]

The composition, structural features, surface morphology, roughness parameters, particle size, and magnetic features of nanostructured Fe‐Co‐Ni deposits manufactured on conducting indium tin oxide‐coated glasses at various electrolyte pH values are studied. The deposit produced at low electrolyte pH contains slightly higher Fe and Co contents but lower Ni content compared to deposits fabricated at high pH values. Further composition analysis confirms that the reduction rates of Fe2+ and Co2+ are higher than the Ni2+ reduction rate. The films consist of nano‐sized crystallites with a strong [111] preferred orientation. The results also reveal that the crystallization of the thin films is affected by the electrolyte pH. Surface analysis shows that the deposit surfaces are composed of nano‐sized particles with different diameters. The mean particle diameter and surface roughness decrease as the pH of the electrolyte decreases. The effect of the electrolyte pH on the morphology is also discussed in terms of surface skewness and kurtosis parameters. Magnetic analysis shows that the resultant deposits have in‐plane hysteresis loops with low and close SQR parameters ranging from 0.079 to 0.108. The results also reveal that the coercive field of the deposits increases from 29.4 Oe to 41.3 Oe as the electrolyte pH decreases from 4.7 to 3.2. LAY DESCRIPTION: The aim of this study is to investigate the impact of the electrolyte pH on the properties of nanostructured Fe‐Co‐Ni/ITO thin films. The chemical composition, structural features and magnetic characteristics of the samples were analyzed through EDX, XRD and VSM, respectively. SEM and AFM methods were used to characterize the surface morphology of the samples. The analysis results showed that the mean particle diameter and surface roughness of the films decreased as the pH of the electrolyte decreased. Besides, lowering the electrolyte pH led to the formation of some pinholes and cracks on the film surface. The change in the surface morphology caused by the pH of the electrolyte and its effect on the magnetic characteristics of the films are discussed in terms of the obtained results. [ABSTRACT FROM AUTHOR]

In 1946 and 1949, Charles Kittel proposed a simple model for the size of ferromagnetic domains that is still widely used nowadays [C. Kittel, Phys. Rev. 70 (1946) 965–971 and Rev. Mod. Phys. 21 (1949) 541–583], including for other ferroic systems, such as ferroelectrics and multiferroics. Kittel’s theory is revisited in this work, with a more detailed demonstration and emphasizing the main assumptions utilized, by using SI units instead of CGS units, as in the original Kittel’s works. The validity limits of the Kittel’s scaling law where the domain width varies with the square root of the sample thickness towards low thicknesses is derived, with the possibility of evolution towards large domains for ultralow thicknesses. Further, Kittel’s model is extended to the case where the sample has a non-vanishing net magnetization and it is shown how magnetization curves at zero temperature can be obtained. This is discussed by supposing constant width of a pair of neighboring domains with opposed magnetization, or by allowing this width to vary as function on the net magnetization of the sample. Though this latter assumption seems to be more reasonable from the point of view of the evolution towards a single domain state at saturation, it seems that the model able to yield most accurate vales of the coercive field is the domain with fixed width of the pair of domains, which justifies the assumption of „domain wall pinning”. The introduction of the demagnetization factor associated with the finite size of the film yields a maximum thickness up to which the films present hysteresis curves. The validity of this theory for ferrelectric domains is also briefly discussed.

The surface, size and ion doping effects on the magnetic, phonon and optical properties of ZnS nanoparticles are studied based on the s-d model including spin-phonon and Coulomb interaction, and using a Green's function theory. The changes of the properties are explained on a microscopic level, due to the different radii between the doping and host ions, which cause different strains—compressive or tensile, and change the exchange interaction constants in our model. The magnetization increases with increasing small transition metal (TM) and rare earth (RE) doping concentration. For larger TM dopants the magnetization decreases. The phonon energies increase with increasing TM, whereas they decrease by RE ions. The phonon damping increases for all doping ions. The changes of the band gap energy with different ion doping concentration is also studied. Band gap changes in doped semiconductors could be due as a result of exchange, s-d, Coulomb and electron-phonon interactions. We have tried to clarify the discrepancies which are reported in the literature in the magnetization and the band gap energy. [ABSTRACT FROM AUTHOR]

In this study, we experimentally and theoretically demonstrated a universal pathway of hysteresis evolution in polarization switching cycling in both antiferroelectric (AFE) and ferroelectric (FE) Hf xZr $_{\text {1-x}}\text{O}\,\,_{{2}}$ (HZO) thin films. AFE films can achieve sufficient remnant polarization and high endurance by engineering the evolution process of double hysteresis merge. Based on this, we propose a new strategy for realizing high-endurance AFE films in non-volatile memory devices. Additionally, a record high endurance >10 12 on 6 nm AFE HZO under full polarization switching conditions at 4.5 MV/cm and 1 MHz is achieved to demonstrate the potential of this strategy. [ABSTRACT FROM AUTHOR]

Investigating the magnetic nanoparticle size and the effective magnetic interactions that form the magnetic domain can lead us to nanoparticles with targeted applications, such as targeted drug delivery and higher resolution MRI imaging. In this study magnetic susceptibility and coercive field properties, and the structure size range of single-domain magnetic capsules with high magnetization were obtained by structural analysis of volumetric DLS properties. In this regard, the role of exchange, anisotropy, and magnetostatic interaction was investigated in the structure of a magnetic capsule containing Fe 3 O 4 nanoparticles (MCap-NPs). The stable capsules were synthesized in an emulsion solution with magnetic surfactants M(AOT) 2 (M = Co, Ni). Vibrating Sample Magnetometer (VSM) and capsule relative volume (CRV) of Dynamic Light Scattering (DLS) were used to determine the magnetic properties of the single-domain (SD) structure. The produced emulsion samples were found to have superparamagnetic properties property with saturation magnetization in the range of 2–6 × 10−3emu/g for NiCap-NPs, and 5-13 × 10−3emu/g for CoCap-NPs. The results show that nanoparticles have the most significant effect on magnetization. The coercive field, the anisotropy energy values, and the SD of M(AOT) 2 were determined using magnetic susceptibility distribution. The outcome results show that the surface of the magnetic capsule plays an essential role in forming a single-domain structure. It was also found that the saturation magnetization of the samples in the emulsion solution is proportional to the nanoparticle density and not to the mass of nanoparticles. All produced samples have distinct peaks in CRV versus capsule size, and each peak follows a log-normal distribution. For both samples, except for the samples with molar ratios ω of 23 (Co3 and Ni4 samples), the positions of the second and third relative volume peaks were constant at 269 ± 3 nm and 424±6 nm, respectively. The behavior of the CRV function normalized to the peak size showed a proportionality between the coercive field and the CRV. [Display omitted] • Magnetic capsules synthesized from M(AOT)2 surfactant containing Fe3O4 nanoparticles have superparamagnetic properties. • Magnetic anisotropy interaction plays an essential role in the formation of magnetic capsule structures containing Fe3O4 nanoparticles. • Magnetic surfactants on the capsule surface play a vital role in the interaction of anisotropy and the formation of single-domain structures. • The distribution of nanoparticles within a capsule affects its saturation magnetic values. [ABSTRACT FROM AUTHOR]

The effect of the dipolar interaction strength on the dynamical hysteresis behavior of the nanodisk is investigated within the Heisenberg model and Monte Carlo simulation. The system is under the effect of the dynamical periodic sinusoidal magnetic field. It has been shown that dipolar interaction strength can induce dynamical phase transition and the transition from the fully dynamically ordered ground state to the weak dynamically ordered ground state. Besides, it has been shown that rising dipolar interaction raises the hysteresis loop area for higher temperatures and a linear relationship between the peak positions of the hysteresis loop area and the temperature locations of the peaks obtained. • The effect of the dipolar interaction on the dynamic hysteresis of the nanodisc is investigated. • Dynamical phases of the according to the strength of the dipolar interaction of the system obtained. • The effect of the dipolar interaction on the hysteresis loop area has been obtained. [ABSTRACT FROM AUTHOR]

The datasets presented in this article are related to materials research on hard ferromagnet in TM-Fe-Si (TM=Ti, Zr, Hf, V, Nb, and Ta) ternary systems. The motivation for data collection is based on the research paper entitled “Novel hard magnetic phase with Zr11.5Fe53Si35.5 composition”. The datasets are composed of scanning electron microscope images, X-ray diffraction (XRD) patterns, and magnetization data for TM7Fe52Si41 annealed at 1050 °C. The chemical compositions of constituent phases were determined by an energy dispersive X-ray spectrometer (EDS). The phase analysis was performed using XRD and EDS results. The Curie temperature of each sample was obtained using magnetization data, and the coercive field was determined for hard ferromagnet samples Zr7Fe52Si41 and Hf7Fe52Si41. The datasets would be useful for developing an Fe-based rare-earth-free permanent magnet, which is one of the central issues of materials science.

Nowadays, spinel ferrites are the subject of research as their structural, magnetic, and dielectric properties are quite prominent for applications in the magnetic and electrical fields. In this work, nanoparticles of manganese-cobalt spinel ferrite (Mn0.7Co0.3LaxFe2−xO4), with 0–10% doping variation of lanthanum ions, are prepared by Sol–Gel auto-combustion route. The powder obtained from the synthesis was annealed in a muffle furnace at 600 °C for 4 h. XRD results confirmed the formation of the face-centered cubic (FCC) structure with a space group of Fd3m in La3+ doped Mn-Co based spinel ferrites. The crystallite size was calculated from the Scherrer formula, found in the 9–14 nm range. Surface morphology was performed using SEM, revealing that non-uniform spherical shape grains with agglomeration are observed with the La3+ ions doping. FTIR transmittance versus wave number pattern represents two absorption bands corresponding to tetrahedral and octahedral sites. The electrical properties are investigated in the 1 MHz to 3 GHz frequency range, and obtained results are described using the Maxwell–Wagner model. A decreasing trend in the impedance and dielectric constant is observed with the increasing applied frequency for all concentrations of La. The highest impedance value is found for the sample with La concentration x = 0.15. Electric modulus Cole–Cole plots showed grain and grain boundary contribution to the conduction process. The hysteresis loop from VSM data confirms that the prepared ferrites are soft magnetic materials. The increasing concentration of La3+ ions significantly declines the coercive field and remanent magnetization. According to the findings, the prepared ferrite materials are appropriate for microwave and charge storage applications. On the other hand, La-doped Mn-Co ferrites are an excellent choice for soft magnetic applications such as transformer cores and magnetic storage devices. [ABSTRACT FROM AUTHOR]

Pure nickel nanoparticles have been synthesized via easy solvothermal route at low temperature, with a high yield of 97%, in the absence of any surfactant, ligand, or external magnetic field. The samples were analyzed through FE-SEM/EDS, XRD, and magnetic measurements. The size of nickel nanoparticles was monitored by adjusting the annealing temperature. The lowest particle size (60 nm) was obtained for an annealing temperature of 130 °C. The XRD patterns exhibited an FCC crystal structure with lattice parameter value close to that of pure Ni (a = 3.525 A). The average anisotropic crystallite size was around 17 nm. The samples showed a soft ferromagnetic behavior with saturation magnetization values lower than pure bulk Ni. The coercivity was between 103 and 218 Oe. The variation of the magnetic parameters was correlated to particles size and morphology of the synthesized powders. [ABSTRACT FROM AUTHOR]

To improve the endurance and polarization switching speed of Hf1âˆ' x Zr x O2 (HZO) ferroelectric films, we designed a 10 nm Hf0.5Zr0.5O2 + ZrO2 (HZZ) nanolaminate structure. Three films with different ZrO2 interlayers thicknesses were compared to find the optimal condition to implement the effect of the topological domain wall which was proposed recently. The HZZ film were deposited by repeatedly stacking ten HZO (∼0.92 nm) and six ZrO2 (∼0.53 nm) layers; they exhibited a dramatic reduction of coercive field without an effective loss of remnant polarization. The endurance at operation voltage increased by more than 100 times compared with that of the solid solution HZO film, and the switching speed was increased by more than two times. The formation of the tetragonal phase-like spacer between the ferroelectric polar regions appears to be the main factor associated with the reduction of the switching barrier and leads to the acceleration of the switching propagation over multiple domains. [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.

In this paper we are communicating a Monte-Carlo based numerical study on the ABA type trilayered Ising spin system incorporating next nearest neighbour interactions. The ABA type system is of growing interest because of the existence of compensation temperature. The effect of next nearest neighbour interactions on compensation temperature and phase transition have been studied by focussing on thermal response of some thermodynamic quantities using the Metropolis algorithm. An effort also made to understand the role of intralayer and interlayer interactions in controlling compensation temperature and critical temperature within such a system. [ABSTRACT FROM AUTHOR]

Sc-doped aluminum nitride is emerging as a new piezoelectric material which can substitute undoped aluminum nitride (AlN) in radio-frequency MEMS applications, thanks to its demonstrated enhancement of the piezoelectric coefficients. Furthermore, the recent demonstration of the ferroelectric-switching capability of the material gives AlScN the possibility to integrate memory functionalities in RF components. However, its high-coercive field and high-leakage currents are limiting its applicability. Residual stress, growth on different substrates, and testing-temperature have already been demonstrated as possible knobs to flatten the energy barrier needed for switching, but no investigation has been reported yet on the whole impact on the dielectric and ferroelectric dynamic behavior of a single process parameter. In this context, we analyze the complete spectrum of variations induced by the applied substrate-RF, from deposition characteristics to dielectric and ferroelectric properties, proving its effect on all of the material attributes. In particular, we demonstrate the possibility of engineering the AlScN lattice cell to properly modify leakage, breakdown, and coercive fields, as well as polarization charge, without altering the crystallinity level, making substrate-RF an effective and efficient fabrication knob to ease the limitations the material is facing. [ABSTRACT FROM AUTHOR]

Exploring the structural, optical, dielectric and magnetic properties of rare earth samarium doped Ca-Mg based Ca 0.5 Mg 0.5 Fe 12−x Sm x O 19 ferrite nanoparticles. [Display omitted] • A series of Samarium (Sm) doped Ca/Mg hexaferrite samples were gabricated. • Structure reveals a consistent magnetoplumbite phase across all samples. • The higher concentrations of samarium resulted in reductions of dielectric loss (ε″) and dielectric constant (ε′). • The material possesses promising magnetic parameters falling within the ranges of 31.52–37.77 emu·g−1 for Ms, 18.16–21.53 emu·g−1 for Mr, and 2.088–2.243 kOe for Hc. The emergence of M-type hexaferrite presents an encouraging alternative to rare earth magnets, due to its economic feasibility and outstanding magnetic properties. This makes it a viable option for applications in the electric automotive and magnetic industry applications. In this study, we utilized a sol–gel auto-combustion technique to synthesize a series of samarium (Sm) doped calcium-magnesium (Ca-Mg) hexaferrite samples having chemical formula Ca 0.5 Mg 0.5 Fe 12−x Sm x O 19 (x = 0.00, 0.05, 0.10, 0.15, and 0.20). The XRD analysis confirmed the crystal structure of the synthesized materials, revealing a consistent magneto-plumbite phase across all samples. Scanning electron microscopy (SEM) investigations further confirmed the homogeneous distribution and agglomeration of nanostructures. FTIR analysis identified the presence of two primary absorption bands in Ca-Mg hexaferrites with both bands exhibiting a shift towards lower frequency ranges with increasing doping levels. The dielectric loss (ε″) and dielectric constant (ε′) were higher at lower frequencies but decreased as the frequency increased. Additionally, higher concentrations of samarium resulted in further reductions in both dielectric loss (ε″) and dielectric constant (ε′). Notably, saturation magnetization (M s) and remanence (M r) values demonstrated an increasing trend with higher degrees of Sm+3 substitution, while coercivity (H c) values exhibited relative stability. Our findings indicate that these materials possess promising magnetic parameters falling within the ranges of 31.52–37.77 emu·g−1 for Ms, 18.16–21.53 emu·g−1 for Mr, and 2.088–2.243 kOe for Hc, suggesting their potential utility across diverse applications including permanent magnets used in electric vehicle motors, storage devices, microwave components, and electromagnetic radiation absorbers. [ABSTRACT FROM AUTHOR]

This comparative Monte Carlo study compares the magnetic properties of β₁₂, χ₃, and striped Borophene structures to reveal differences in magnetization, susceptibility, blocking temperature, and coercive field for each lattice. Beyond merely exploring these properties, the study delves into the crucial influence of exchange coupling (J) and external magnetic field (H) on both blocking temperature and hysteresis cycles. The research sheds light on how the intricate geometry of 2D Borophene materials plays a pivotal role in shaping their magnetic responses. This emphasizes the broader significance of geometric considerations.This multifaceted analysis provides insights into the interplay between structural features and magnetic behaviors, advancing the utilization of Borophene for magnetic applications. [ABSTRACT FROM AUTHOR]

MoO2-Fe2O3 nanoparticle systems were successfully synthesized by mechanochemical activation of MoO2 and α-Fe2O3 equimolar mixtures throughout 0–12 h of ball-milling. The role of the long-range ferromagnetism of MoO2 on a fraction of more defect hematite nanoparticles supporting a defect antiferromagnetic phase down to the lowest temperatures was investigated in this work. The structure and the size evolution of the nanoparticles were investigated by X-ray diffraction, whereas the magnetic properties were investigated by SQUID magnetometry. The local electronic structure and the specific phase evolution in the analyzed system versus the milling time were investigated by temperature-dependent Mössbauer spectroscopy. The substantially shifted magnetic hysteresis loops were interpreted in terms of the unidirectional anisotropy induced by pinning the long-range ferromagnetic order of the local net magnetic moments in the defect antiferromagnetic phase, as mediated by the diluted magnetic oxide phase of MoO2, to those less defect hematite nanoparticles supporting Morin transition. The specific evolutions of the exchange bias and of the coercive field versus temperature in the samples were interpreted in the frame of the specific phase evolution pointed out by Mössbauer spectroscopy. Depending on the milling time, a different fraction of defect hematite nanoparticles is formed. Less nanoparticles supporting the Morin transition are formed for samples exposed to a longer milling time, with a direct influence on the induced unidirectional anisotropy and related effects. [ABSTRACT FROM AUTHOR]

Ni0.75Zn0.25Fe2O4 has been modified with Zr and Co in stoichiometry of Ni0.75Zn0.2ZrxCoxFe2-2xO4 (x = 0.00, 0.01, 0.02, 0.03, 0.04) in order to get improved electric and magnetic properties. The samples are synthesized by using sol–gel with auto-combustion method. The XRD patterns show their single-phase cubic spinel, and FT-IR spectra confirm F d 3 ¯ m ( O h 7 ) space group. The lattice parameter initially increased from 8.3253 to 8.3440 Å, thereafter decreasing to 8.3121 Å with increasing doping concentration. The crystallite size increased from 32.238 to 46.299 nm after that it decreased to 30.865 nm on commingle the Zr and Co ions in precursor material. The grain size initially increased from 59.9375 to 92.5675 µm; later gradual decrease was observed up to 56 µm on dilute the stoichiometric equation with Zr and Co ions. On inter-mix of Zr and Co ions in Ni0.75Zn0.25Fe2O4, the X-ray density shows the decreasing trend from 5.3938 g/cm3 to 5.3508 g/cm3. The overall porosity% was observed as in descending order from 11.6945% to 10.4506%. On devalue, the Fe3+ ions with Zr and Co ions in Ni0.75Zn0.25Fe2O4. The crystal catalysis activity (specific surface area) shows decreasing trend with raise of doping ions of Zr and Co in Ni0.75Zn0.25Fe2O4. The wave number for tetrahedral sites and octahedral sites are in increasing trend from 395 to 405/cm to 405/cm and 589 /cm to 603/cm, respectively, on surge of Zr and Co ions in precursor material. The corresponding force constant for tetrahedral sites and octahedral sites shows similar trend from 24.99 N/m to 25.59 N/m and 19.552 N/m to 20.554 N/m on augmentation of Zr and Co concentration. The dielectric constant increased from 1649 to 3210, and the corresponding loss factor shows exact trend from 0.07912 to 0.1965 by the application of external field. The AC conductivity also increased from -13.6970 to -13.0125 with increasing doping concentration. On escalation of adulterate, the saturation magnetization and net magnetic moment decreased from 122.6emu/gm to 74 emu/gm. The permeability is inflating from 67.54 to 139 on injecting of Zr and Co in stoichiometric equation of Ni0.75Zn0.25Fe2O4. The crystal shape anisotropy constant gradually decreased from 1357 erg/cm3 to 246erg/cm3on raising doping concentration in stoichiometric equation. On loading the Zr and Co concentration in sample, the coercive filed (Hc) diminish from 22.137 Os to 6.5705Os. The Y-K angles are raised from 14.66° to 27.19° on swarming the Zr and Co ions concentration in Ni0.75Zn0.25Fe2O4. [ABSTRACT FROM AUTHOR]

Improving the performance of electrical steels within the magnetic circuits is essential to save energy. The domain refinement through local surface treatment by laser is an effective technique to reduce the iron losses in grain-oriented iron silicon steels. To interpret the mechanism of this technique, we have quantitatively studied the impact of nanosecond pulse laser treatment on the magnetic properties of grain-oriented Fe(3%wt)Si sheets. We measured the total power loss and apparent permeability of the samples using a Single-Sheet Tester (SST). The laser treatment resulted in a loss reduction of up to 24% compared to the average power loss of standard samples at 50 Hz. At mid-induction levels, the reduction was also accompanied by an improvement in apparent permeability. A dynamic magnetic behavior law was used to identify a dynamic property A including information on density, surface area and wall mobility and another internal permeability property Λ representative of static field and magnetization characteristics. Lastly, we presented the behavior of these properties under different laser treatment. [ABSTRACT FROM AUTHOR]

Previous studies have suggested that the operating voltage and energy-delay properties of a nanoelectromechanical (NEM) system can be improved using the negative capacitance (NC) effect of ferroelectric materials. However, the advantages of using the NC effects alone have been utilized for perovskite ferroelectric materials, which is incompatible in complementary metal-oxide-semiconductor (CMOS) fabrication processes. In this work, a CMOS-compatible HfO2-based ferroelectric material is used for the NC + NEM system. The effects of the ferroelectric properties [i.e., remnant polarization (Pr) and coercive field (Ec)] on the NC + NEM system performance are studied in detail. The results show that the NC + NEM system can operate as a relay or a memory device depending on the Pr and Ec values. Moreover, the pull-in/out voltages of the NC + NEM system are more sensitively affected by Ec rather than Pr and decrease as Ec increases. The device design guideline with appropriate Pr and Ec values of the HfO2-based ferroelectric material is thus developed and discussed to improve the electrical characteristics of NC + NEM relay/memory devices.

A series ofCd0.45Co0.55Fe2-yEuyO4( y = 0.0, 0.1, 0.2, 0.3) spinel nanoferrites (SNFs) were synthesized using a self-igniting process and employed as electrode materials for supercapacitor applications. The results demonstrated the formation of a single SNFs phase, as shown by the XRD data. The crystallite size lies between the range of 29.30-51.12 nm. The porosity percentage is within the range of 31.37%-32.99%. Rietveld refinement of XRD and Raman analysis revealed the pure spinel phase and no secondary phase was observed. The saturation magnetization and magnetic anisotropy were also decreased with the addition of Eu 3+ in Cd-Co SNFs. The high coercive field was enhanced for Eu 3+ doping as compared to pure Cd-Co SNFs. The dielectric constant was improved with the substitution of Eu 3+ in Cd-Co SNFs. The dielectric tangent loss was reduced with the doping of Eu 3+ . The electrochemical performance of the Eu 3+ doped Cd-Co SNFs achieved an impressive maximum specific capacitance at a lower scan rate. Based on these findings, the outstanding electrochemical performance of the Eu 3+ doped Cd-Co SNFs suggests their potential as promising materials for high-frequency, magnetic ferrofluid, and supercapacitor electrodes., (© 2024 IOP Publishing Ltd.)

The surface, size and ion doping effects on the magnetic, phonon and optical properties of ZnS nanoparticles are studied based on the s-d model including spin-phonon and Coulomb interaction, and using a Green’s function theory. The changes of the properties are explained on a microscopic level, due to the different radii between the doping and host ions, which cause different strains—compressive or tensile, and change the exchange interaction constants in our model. The magnetization increases with increasing small transition metal (TM) and rare earth (RE) doping concentration. For larger TM dopants the magnetization decreases. The phonon energies increase with increasing TM, whereas they decrease by RE ions. The phonon damping increases for all doping ions. The changes of the band gap energy with different ion doping concentration is also studied. Band gap changes in doped semiconductors could be due as a result of exchange, s-d, Coulomb and electron-phonon interactions. We have tried to clarify the discrepancies which are reported in the literature in the magnetization and the band gap energy.

The gallium-doped hafnium oxide (Ga-HfO 2 ) films with different Ga doping concentrations were prepared by adjusting the HfO 2 /Ga 2 O 3 atomic layer deposition cycle ratio for high-speed and low-voltage operation in HfO 2 -based ferroelectric memory. The Ga-HfO 2 ferroelectric films reveal a finely modulated coercive field ( E c ) from 1.1 (HfO 2 /Ga 2 O 3 = 32:1) to an exceptionally low 0.6 MV/cm (HfO 2 /Ga 2 O 3 = 11:1). This modulation arises from the competition between domain nucleation and propagation speed during polarization switching, influenced by the intrinsic domain density and phase dispersion in the film with specific Ga doping concentrations. Higher E c samples exhibit a nucleation-dominant switching mechanism, while lower E c samples undergo a transition from a nucleation-dominant to a propagation-dominant reversal mechanism as the electric field increases. This work introduces Ga as a viable dopant for low E c and offers insights into material design strategies for HfO 2 -based ferroelectric memory applications.

Bismuth substituted nickel ferrite (NiFe2−xBixO4 at x = 0.0–1.0) nanoparticles are synthesised by co-precipitation method. The crystal structure, grain size, morphology and magnetic properties are analysed by using XRD, FTIR, SEM, and VSM. XRD confirm the crystalline nature with single-phase cubic spinel structure. The average crystallite size calculated using Debye Scherrer and modified Scherrer formula is in the range of 20–65 nm. SEM image manifests that the particles are agglomerated and with non-uniformity shape. The presence of elemental composition such as Ni, Fe, Bi and O has been confirmed by EDX. In FTIR spectra, tetrahedral (A) and octahedral (B) sites are found in the range of 525–620 cm−1 and 460–465 cm−1, respectively. Their magnetic properties are scrutinized using VSM. At x = 0, the prepared nanoparticles are very useful for magnetic targeting carriers. The coercivity, saturation magnetization, remanence, squareness ratio, Bohr magneton and Curie temperature values decrease as the bismuth content increases. M–T curve reveals the superparamagnetic behaviour at room temperature. [ABSTRACT FROM AUTHOR]