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The B20 type chiral magnet FeGe exhibits the formation of skyrmion-lattice (SkL) phases in the vicinity of the magnetic ordering temperature. The SkL is a magnetic superlattice composed of vortex-type topological spin objects, and it has experimentally been known that its formation requires the existence of an intermediate (IM) phase between SkL and the paramagnetic (PM) phases. We take interest in how the crystal lattice experiences the formation of these topological spin texture. In this study, we observed the so-called spin–orbit coupling induced magnetostriction related to these topological spin texture formation, in addition to the ac magnetization anomalies. The temperature and magnetic field dependences of the lattice parameter reflected the transformation of phases, such as helimagnetic (HM), SkL, IM, conical (CM), and PM phases. In the PM region, a phase characterized as gaseous skyrmions was detected similarly to the case of the same B20 type MnSi. Furthermore, the HM, CM, and IM phases were also divided into two regions. Thus, the precise phase diagram near T c was reconstructed from the prospect of the magnetostriction such that we demonstrated that the stabilization of skyrmions needs a finite magnetic field. [ABSTRACT FROM AUTHOR]

The cellulose fibers that form washi are longer than those of regular paper made from wood pulp. Hence, the mechanical properties of washi can be higher than those of conventional paper. This study evaluated the magnetic, magnetostrictive, and tensile properties of negative magnetostrictive cobalt ferrite (CoFe2O4) particle dispersed handmade washi (washi−CoFe2O4). The CoFe2O4 additives magnetized the washi, which displayed negative magnetostriction with the fiber direction perpendicular to the magnetic field and in the parallel fiber direction. Concerning the mechanical properties, the washi−CoFe2O4 displayed an elongation of up to 77% after yielding. [ABSTRACT FROM AUTHOR]

In the current work, laser thermal treatment of the FeSiB amorphous foil with a single linear laser track was carried out. The resultant microstructure and phase evolution were examined with the aid of x-ray diffraction, differential scanning calorimetry, and site-specific transmission electron microscopy. The laser power was kept constant at 100 W, whereas, laser beam scanning speeds were varied in the range of 500–235 mm/s, generating corresponding laser fluences of 0.42–0.91 J/mm 2 on the sample surface. Laser fluences of up to 0.48 J/mm 2 structurally relaxed the FeSiB foil, retaining the amorphous structure. Laser fluences of higher than 0.48 J/mm 2 led to partial crystallization of FeSiB amorphous foils. The crystallite sizes were in the range of 11–31 nm (laser fluence of 0.49–0.91 J/mm 2). α -FeSi formed as a major phase of partial crystallization while its quantity steadily increased from 3.6 to 46 vol. % with laser fluence (laser fluence 0.49–0.91 J/mm 2). Fe 2 B formed in recognizable quantities (≥ 2%) for laser fluences ≥ 0.53 J/mm 2. Laser fluences leading to structural relaxation and evolution of predominantly α -FeSi phase exerted minimal effects on ratios of intrinsic coercivities to saturation compared to the as-cast FeSiB amorphous foil. On the contrary, formation of Fe 2 B in significant quantities (≥ 2 %) led to the steady increase in intrinsic coercivities and remanence to saturation ratios as a function of laser fluence indicating a loss in soft magnetic characteristics. Nonetheless, continuous increase in fractions of α -FeSi with laser fluence led to a steady improvement in saturation magnetostriction of the FeSiB foil. [ABSTRACT FROM AUTHOR]

Due to the magnetostriction effect, a magnetic material changes its dimensions when it is magnetized. In this work, we show how in a magnetostrictive bilayer structure comprising two materials with magnetostriction constants of opposite signs, the magnetic switching is affected by magnetoelastic coupling. While the layer with positive magnetostriction tries to elongate in the direction of the applied magnetic field, the layer with negative magnetostriction tries to contract. In the studied bilayers, the mechanical influence of each magnetostrictive layer on the other is of the opposite sign because of their opposite magnetostrictive constants. Since magnetoelasticity is not an interfacial interaction but an intrinsic property of magnetic materials, the mechanical strain promoted by the applied magnetic field affects the layers as a whole. The net effect is a simultaneous reversal of magnetization of the two layers regardless of their thicknesses. This behavior has been studied in bilayers with different thickness ratios comprising Ni90Fe10, negative magnetostriction and Fe70Ga30, positive magnetostriction. These results demonstrate the possibility of using this physical mechanism to beat the critical limit thickness imposed by interfacial interactions in magnetically coupled multilayers in such a way that the magnetization reversal is made in unison regardless of the layer thickness. [ABSTRACT FROM AUTHOR]

Magnetostrictive bimorphs consisting of positive and negative magnetostrictive materials such as FeGa and Ni respectively were made in the form of (a) multilayers containing Si/Ni/FeGa and (b) stacking consisting of Ni/Si/FeGa by sputtering technique on Si substrates. While the thickness of the FeGa film was maintained at 200 nm for all the films, Ni films were grown with two different thicknesses, viz., 100 and 200 nm. Magnetostrictive response of these bimorphs was compared with FeGa unimorph deposited on Si. Structural studies indicated FCC and BCC structure for Ni and FeGa films respectively. Magnetization studies showed a decrease in saturation magnetization with increase in Ni content owing to the lower magnetization of Ni when compared to FeGa. Considerable enhancement in tip deflection has been observed in the bimorph structure when compared with pure FeGa film. [ABSTRACT FROM AUTHOR]

Minimization or tailoring of magnetic anisotropies in the order of magneto-crystal, magneto-elastic and external field-induced anisotropies are effective way of improving soft-magnetism in nanocrystalline alloys. The recently developed Fe-rich nanocrystalline alloys have been found to exhibit positive magnetostriction behaviour and magnetic coercivity twice that of FINEMET alloys, after optimal annealing. This makes uniaxial tensile-stress annealing a promising method to improve the soft-magnetism of these alloys. In that direction, the present study investigates the influence of tensile stress annealing on structure, soft-magnetic, magnetostriction and core-loss properties of Fe-rich Fe83Si2B9P4Nb1Cu1 nanocrystalline ribbons. The samples were uniformly annealed at 480 °C for 4 min with varying uniaxial tensile stress ranging from 0 to 180 MPa. The XRD results showed that all annealed ribbons had a uniform nanocrystalline microstructure consisting of a BCC α-Fe(Si) phase with an average grain size of less than 20 nm, irrespective of the applied stress. However, the magnetic properties were highly sensitive to the magnitude of the tensile stress during nanocrystallization annealing. The optimal tensile stress ranging from 90-140 MPa resulted in the best combination of soft-magnetic properties (11–12 A/m) and high squareness ratio (0.8-0.9). These ribbons also depicted longitudinal anisotropy (Ku ≤ 0). On the other hand, tensile stress above 165 MPa resulted in the deterioration of magnetic properties (> 24 A/m) and transverse anisotropy behaviour (Ku > 0). The transformation of tensile stress-induced anisotropy from longitudinal to transverse was characterized by the reduction of the magnetostriction constant and change in the magnetization process. The core-loss plots (50-1000 Hz) showed a reduction for optimal stress-annealed (90-140 MPa) ribbons and a drastic increase for 165-180 MPa ribbons. The study highlights the beneficial role of controlled tensile stress annealing in improving the soft-magnetism of Fe-rich nanocrystalline alloys with positive magnetostriction. [ABSTRACT FROM AUTHOR]

Soft magnetoactive elastomers (MAEs) are currently considered to be promising materials for actuators in soft robotics. Magnetically controlled actuators often operate in the vicinity of a bias point. Their dynamic properties can be characterized by the piezomagnetic strain coefficient, which is a ratio of the time-harmonic strain amplitude to the corresponding magnetic field strength. Herein, the dynamic strain response of a family of MAE cylinders to the time-harmonic (frequency of 0.1–2.5 Hz) magnetic fields of varying amplitude (12.5 kA/m–62.5 kA/m), superimposed on different bias magnetic fields (25–127 kA/m), is systematically investigated for the first time. Strain measurements are based on optical imaging with sub-pixel resolution. It is found that the dynamic strain response of MAEs is considerably different from that in conventional magnetostrictive polymer composites (MPCs), and it cannot be described by the effective piezomagnetic constant from the quasi-static measurements. The obtained maximum values of the piezomagnetic strain coefficient (∼ 10 2 nm/A) are one to two orders of magnitude higher than in conventional MPCs, but there is a significant phase lag (35–60°) in the magnetostrictive response with respect to an alternating magnetic field. The experimental dependencies of the characteristics of the alternating strain on the amplitude of the alternating field, bias field, oscillation frequency, and aspect ratio of cylinders are given for several representative examples. It is hypothesized that the main cause of observed peculiarities is the non-linear viscoelasticity of these composite materials. [ABSTRACT FROM AUTHOR]

This paper presents an asymptotic two-dimensional (2D) finite-deformation theory for a thin magnetoelastic sheet starting from a three-dimensional (3D) variational form. This theory is used to model wrinkling phenomena under applied traction and external magnetic field. The resulting 2D potential energy is specialized to an isotropic, in compressible material, and the expressions for material constants, i.e., elasticity tensor, magnetoelastic coupling constant, and permeability, are obtained as a function of the applied magnetic field. The formulation is further simplified assuming reflection symmetry about the mid-surface of the sheet. Strong form of the resulting 2D governing equations are obtained by setting the first variation of potential energy functional to zero. The resulting governing equations are used to analyze wrinkling in a stretched rectangular sheet placed in a uniform magnetic field. Approximate analytical solutions are obtained by linearizing the 2D plate equation for small slopes. The effect of magnetic field and applied stretch on onset of wrinkling and amplitude of wrinkles is studied. [ABSTRACT FROM AUTHOR]

Reducing the saturation magnetostriction is an effective way to improve the performance of soft magnetic materials and reduce core losses in present and future applications. The magnetostrictive properties of binary Fe-based alloys are investigated for a broad variety of alloying elements. Although several studies on the influence of Cu-alloying on the magnetic properties of Fe are reported, few studies have focused on the effect on its magnetostrictive behavior. High pressure torsion deformation is a promising fabrication route to produce metastable, single-phase Fe-Cu alloys. In this study, the influence of Cu-content and the chosen deformation parameters on the microstructural and phase evolution in the Fe-Cu system is investigated by scanning electron microscopy and synchrotron X-ray diffraction. Magnetic properties and magnetostrictive behavior are measured as well. While a reduction in the saturation magnetostriction λs is present for all Cu-contents, two trends are noticeable. λs decreases linearly with decreasing Fe-content in Fe-Cu nanocomposites, which is accompanied by an increasing coercivity. In contrast, both the saturation magnetostriction as well as the coercivity strongly decrease in metastable, single-phase Fe-Cu alloys after HPT-deformation. [ABSTRACT FROM AUTHOR]

In this paper, we explore the benefits of using a magnetostrictive component in a variable reluctance energy harvester. The intrinsic magnetic field bias and the possibility to utilize magnetic force to achieve pre-stress leads to a synergetic combination between this type of energy harvester and magnetostriction. The proposed energy harvester system, to evaluate the concept, consists of a magnetostrictive cantilever beam with a cubic magnet as proof mass. Galfenol, Fe81.6Ga18.4, is used to implement magnetostriction. Variable reluctance is achieved by fixing the beam parallel to an iron core, with some margin to create an air gap between the tip magnet and core. The mechanical forces of the beam and the magnetic forces lead to a displaced equilibrium position of the beam and thus a pre-stress. Two configurations of the energy harvester were evaluated and compared. The initial configuration uses a simple beam of aluminum substrate and a layer of galfenol with an additional magnet fixing the beam to the core. The modified design reduces the magnetic field bias in the galfenol by replacing approximately half of the length of galfenol with aluminum and adds a layer of soft magnetic material above the galfenol to further reduce the magnetic field bias. The initial system was found to magnetically saturate the galfenol at equilibrium. This provided the opportunity to compare two equivalent systems, with and without a significant magnetostrictive effect on the output voltage. The resonance frequency tuning capability, from modifying the initial distance of the air gap, is shown to be maintained for the modified configuration (140 Hz/mm), while achieving RMS open-circuit coil voltages larger by a factor of two (2.4 V compared to 1.1 V). For a theoretically optimal load, the RMS power was simulated to be 5.1 mW. Given the size of the energy harvester (18.5 cm3) and the excitation acceleration (0.5 g), this results in a performance metric of 1.1 mW/cm3g2. [ABSTRACT FROM AUTHOR]

As a kind of magnetostrictive ceramics, cobalt ferrites are widely concerned because of its large magnetostriction and high resistivity, which are ideal for high-frequency applications. But, the high driving magnetic field due to the high magnetocrystalline anisotropy limits the practical applications of cobalt ferrites, thus, it is a still a challenge to find a balance between high magnetostriction properties and low driving magnetic fields. In this work, we investigated the effects of partially substitution of Ga3+ for Fe3+ on grain orientation and magnetic properties, attempting to maintain high magnetostriction while reducing the driving magnetic field. The CoFe 2-x Ga x O 4 (x=0, 0.05, 0.1, 0.15) with single-phase spinel structure were prepared by the conventional solid-state method. The saturation magnetization M S increased with the increase of Ga concentration, meanwhile the coercivity H c and magnetocrystalline anisotropy constant K 1 significantly decreased, which indicates the better soft magnetic characteristics of the Ga-doped cobalt ferrites. The oriented CoFe 2-x Ga x O 4 samples were obtained using magnetic field orientation technique during the powder forming process. The <001> preferred orientation was achieved in CoFe 2 O 4 samples. However, the <001> orientation degree decreased with the substitution of Ga, and the preferred orientation has changed into <111> at x=0.15. The Ga substitution affected the magnetocrystalline anisotropy and grain orientation, thereby affecting the magnetostrictive properties. As for the non-oriented samples, although the maximum magnetostrictive strain slightly decreased with Ga substitution, while there was a significant drop in the magnetostrictive saturation field. However, the magnetostriction of the oriented samples decreased significantly with the substitution of Ga due to the change of grain orientation from <001> to <111>. [ABSTRACT FROM AUTHOR]

The effect of plastic deformation on the structure, phase composition, and magnetic parameters of maraging steel 08Kh15N5D2T was studied. The hysteresis, electromagnetic, and magnetostrictive characteristics were measured both in a closed magnetic circuit using the Remagraph C-500 hysteresis graph and by means of attached magnetic transducers. The regions of plastic deformation are experimentally determined in which the behavior of the magnetic parameters and their relationship vary with changes in structure and phase composition. Informative parameters are proposed that can be used to control variations in the structure and phase composition of the studied steel. [ABSTRACT FROM AUTHOR]

We analytically investigate the Fano-type optical response and the four-wave mixing (FWM) process by exploiting the magnetoelasticity of a ferromagnetic material. The deformation of the ferromagnetic material plays the role of mechanical displacement, which is simultaneously coupled to both optical and magnon modes. We report that the magnetostrictively induced displacement leads to realization of Fano profiles in the output field and is effectively well-tuned through adjusting the system parameters, such as effective magnomechanical coupling, magnon detuning, and cavity detuning. It is found that the magnetoelastic interaction also gives rise to the FWM phenomenon. The number of the FWM signals mainly depends upon the effective magnomechanical coupling and the magnon detuning. Moreover, the FWM spectrum exhibits suppressive behavior upon increasing (decreasing) the magnon (cavity) decay rate. The present scheme will open new perspectives in highly sensitive detection and quantum information processing. [ABSTRACT FROM AUTHOR]

The current work presents the study of three alloys, (1) the binary Fe0.7Co0.3 alloy (atomic fraction), (2) the addition of 3 at. % of Ti, and (3) the addition of 3 at. % of Ti and 1% of Nb. The interest is to increase the permeability of this binary alloy due to the additions of Ti and Nb, since Fe–Co alloys with Co content in the range of 27–35 at. % have much lower permeability than the commercial equiatomic alloy. The advantage of low Co Fe–Co alloys is the lower price compared to the equiatomic one. The alloys were produced by arc melting and were subsequently hot rolled and annealed in the final thickness at 1200 °C over 24 h. Microstructure characterization revealed single α-phased alloys with body centered cubic structures. Positive results were observed in the magnetic and electric properties of the (Fe0.70Co0.30)97Ti3 alloy compared to Fe0.7Co0.3, meaning the decreasing saturation magnetostriction λs, and the growth of the maximum relative permeability by 24% and of the resistivity by 63%, occurred without a change in the coercive field and in the maximum magnetic induction. The (Fe0.7Co0.3)97Ti3 alloy's maximum magnetic relative permeability is μrmax = 855 and occurs at a field of only 160 A/m, this field being more than two times lower compared to the one of the binary alloy. On the other hand, the addition of Ti + Nb has improved the deformation performance of the (Fe0.7Co0.3)97Ti3 alloy at high temperatures and did not change the magnetostriction, nor the resistivity. The quaternary alloy presents a maximum magnetic relative permeability of μrmax = 270 at 1960 A/m and a maximum magnetic induction reduced by 14% compared to the other two alloys. [ABSTRACT FROM AUTHOR]

Abstract During geomagnetic storms, geomagnetically induced currents (GICs) occur in the power grid. GIC is a quasi‐direct current, which is represented by using a fixed DC current, the authors propose an approach that combines field‐circuit‐coupled and weakly coupled magneto‐mechanical models to investigate the magnetostriction characteristics of single‐phase, four‐column autotransformer cores excited by GICs. A non‐linear magnetostrictive constitutive model that considers the impact of stress and magnetisation intensity on ferromagnetic materials is introduced. The model reveals that the strain in the core initially increases as the magnetisation intensity increases; however, when the core begins to saturate, the magnetostrictive strain weakens as the magnetisation intensity increases. Moreover, the results of multiphysics finite‐element modelling are experimentally verified using a direct current bias platform. The results show that when excited by GICs, there is an enhancement in the vibration of the iron core, and the harmonic content of the vibration acceleration increases considerably, with the odd harmonics most significantly increasing in amplitude. The conclusion drawn is that GICs can exacerbate transformer vibration and significantly increase the content of harmonics, especially odd harmonics.

Magnetostrictive thin films, exhibit significant utility as functionalization materials for Surface acoustic wave sensors designed for magnetic field measurements. This research investigates the influence of annealing under vacuum and magnetic field at various temperatures on the magnetic properties of the FeCo/TbCo2 thin film and therefore on the sensitivity of shear and Rayleigh acoustic waveguides functionalized with these magnetic layers. The observed effects include a reduction in magnetic anisotropy field and an increase in magnetostriction. XPS and TEM coupled with EDS microanalysis provide insights into the variations in the properties of the nanostructured magnetic film. To safeguard the magnetic film, a thin layer of SiO2 is deposited on top, serving as a protective shield. The inclusion of this layer amplifies sensitivity to applied magnetic fields for modes with shear polarization while reducing sensitivity for Rayleigh mode. In ST‐cut Quartz, the shear waves become waveguided upon the incorporation of magnetic thin films, with further enhancement achieved by introducing a SiO2 layer. Rayleigh waves are evanescent modes, the penetration depth is in the order of wavelength, and the addition of SiO2 decrease the wave confinement and therefore the sensitivity. The findings are supported by a theoretical model and experimentally validated results. [ABSTRACT FROM AUTHOR]

In this paper, we establish the existence of global-in-time weak solutions for the Landau–Lifschitz–Gilbert equation with magnetostriction in the case of mixed boundary conditions. From this model, we derive by asymptotic method a two-dimensional model for thin ferromagnetic plates taking into account magnetostrictive effects. [ABSTRACT FROM AUTHOR]

This article focuses on the analytical investigation of strain-induced ultrafast magnetic domain wall motion in a bilayer structure composed of piezoelectric and magnetostrictive materials. We perform the analysis within the framework of the inertial Landau–Lifshitz–Gilbert equation, which describes the evolution of magnetization in cubic magnetostrictive materials. By employing the classical traveling wave ansatz, the study explores how various factors such as magnetoelasticity, dry-friction, inertial damping, chemical composition, crystal symmetry, and tunable external magnetic field influence the motion of the domain walls in both steady-state and precessional dynamic regimes. The results provide valuable insights into how these key parameters can effectively modulate dynamic features such as domain wall width, threshold, Walker breakdown, and domain wall velocity. The obtained analytical results are further numerically illustrated, and a qualitative comparison with recent observations is also presented. [ABSTRACT FROM AUTHOR]

Magnetostrictive biosensors can often consist of magnetostrictive transducers, functional coatings, signal excitation, bioprobes, and detection systems. These sensors can be used to generate and transmit the signals via magnetic field coupling. Among them, the magnetostrictive material can be subjected to the excitation of alternating magnetic fields during detection. Once the frequency of the magnetic field matches the natural frequency of sensors, the resonance can occur for an impedance signal. A direct current (DC) bias magnetic field can also be applied to amplify the signal. At the same time, the adsorption of pathogens can increase the mass of the sensor, leading to the variation in the resonance frequency. Some key factors (such as manufacturing costs, detection sensitivity, and efficiency) can significantly influence the performance of magnetostrictive biosensors. In this study, a series-connected magnetostrictive biosensor was developed to integrate two sensors with different sizes. A Fe-based amorphous soft magnetic alloy was selected with 25 µm thick as the transducer. The functional coating with a 350 nm thick was prepared as the polyvinyl alcohol (PVA) film from a 2.5% PVA solution. Single sensors were used with the dimensions of 3.6×0.6, 4.8×0.8, 6.0×1.0, 7.2×1.2, and 8.4 mm×1.4 mm as the control groups. Series connections were made as follows: 3.6×0.6 with 6.0×1.0, 4.8×0.8 with 7.2×1.2, and 6.0× 1.0 with 8.4 mm×1.4 mm. An impedance analyzer was applied with a 50 mV alternating current (AC) excitation and a 6V DC bias voltage. A comparative analysis was conducted on the resonance parameters of single- and series-connected sensors. The series-connected sensors were selected with the dimensions of 4.8 mm×0.8 and 7.2×1.2 mm to detect Escherichia coli (E. coli) suspensions with concentrations ranging from 10 to 108 CFU/mL with/without antibodies. The adsorption of pathogenic bacteria was analyzed on some shifts in resonance frequencies. Scanning electron microscopy (SEM) was used to observe the surface adsorption of pathogenic bacteria on sensors. A systematic investigation was made to explore the relationship between the resonance frequency shifts and immersion times when the E. coli was detected in the food solutions using series-connected magnetostrictive sensors. The results revealed that there was a close relationship between the resonance parameters and the size of single- and series-connected sensors. The resonance frequency decreased, as the sensor size increased, whereas, the resonance amplitude increased. The magnitude of the resonance amplitude was quantitatively analyzed using the resonance frequency. Additionally, the series-connected magnetostrictive biosensors demonstrated that there was nearly unchanged in the resonance frequencies, but there was an increase in the resonance amplitudes, compared with the single sensors. Therefore, an enhanced strength response was achieved as well. The frequency shift of resonance increased with the higher concentrations of E. coli suspensions. Antibody-loaded sensors exhibited significantly larger resonance frequency shifts than those without antibodies, due to the specific binding between antibodies and E. coli. The detection limit of the series-connected sensor was determined to be 10² CFU/mL. There were relatively close frequency shifts of resonance in the 4.8mm× 0.8mm and the 7.2mm×1.2mm sensors in the same loading conditions, due to the higher number of bacteria that adsorbed by the larger sensor (7.2mm×1.2 mm). The small difference in mass between the two sensors resulted in similar frequency shifts. SEM observations confirmed that the frequency shifts of resonance were caused by the adsorption of E. coli. The sensor demonstrated excellent detection. The sensor with the antibody loading adsorbed significantly more E. coli on the surface, compared with the sensor without antibodies. This finding was consistent with the measurements on the frequency shift of resonance. The sensor achieved stable detection within 20 minutes. The novel series-connected magnetostrictive biosensor can offer high sensitivity, strong signal strength, high detection efficiency, simple manufacturing, low cost, and ease of use. This finding can provide a strong reference to apply biosensors to safety detections in the food industry. [ABSTRACT FROM AUTHOR]

We analyze the behavior as t → ∞ of strong solutions of the initial-boundary-value problem for a system of semilinear equations of magnetoelasticity with dissipative term in exterior domains. The estimates of energy decay are obtained. For the vector of magnetic induction, the estimates of decay are established in the spaces L∞ and L2. [ABSTRACT FROM AUTHOR]

Inkjet printing of magnetic materials has increased in recent years, as it has the potential to improve research in smart, functional materials. Magnetostriction is an inherent property of magnetic materials which allows strain or magnetic fields to be detected. This makes it very attractive for sensors in the area of structural health monitoring by detecting internal strains in carbon fibre-reinforced polymer (CFRP) composite. Inkjet printing offers design flexibility for these sensors to influence the magnetic response to the strain. This allows the sensor to be tailored to suit the location of defects in the CFRP. This research has looked into the viability of printable soft magnetic materials for structural health monitoring (SHM) of CFRP. Magnetite and nickel ink dispersions were selected to print using the JetLab 4 drop-on-demand technique. The printability of both inks was tested by selecting substrate, viscosity and solvent evaporation. Clogging was found to be an issue for both ink dispersions. Sonicating and adjusting the jetting parameters helped in distributing the nanoparticles. We found that magnetite nanoparticles were ideal as a sensor as there is more than double increase in saturation magnetisation by 49 Am2/kg and more than quadruple reduction of coercive field of 5.34 kA/m than nickel. The coil design was found to be the most sensitive to the field as a function of strain, where the gradient was around 80% higher than other sensor designs. Additive layering of 10, 20 and 30 layers of a magnetite square patch was investigated, and it was found that the 20-layered magnetite print had an improved field response to strain while maintaining excellent print resolution. SHM of CFRP was performed by inducing a strain via bending and it was found that the magnetite coil detected a change in field as the strain was applied. [ABSTRACT FROM AUTHOR]

Establishing a reliable control of perpendicular magnetic anisotropy (PMA) is challenging but essential for the full utilization of rare‐earth iron garnets in spintronic devices. In this study, a feasible approach to enhance the PMA of ferrimagnetic thulium iron garnet (TmIG) films is presented. This approach involves precise adjustments in cation stoichiometry and epitaxial strain state. By fine‐tuning the pre‐ablation process and oxygen partial pressure during pulsed laser deposition, a series of high‐quality TmIG films can grow with variable cation stoichiometry, i.e., the Tm/Fe molar ratio. The finding reveals that cation stoichiometry plays a crucial role in determining the magnetic properties of the TmIG films. Particularly, the stoichiometric TmIG film has the strongest PMA due to the maximized magnetostriction coefficient. Combining this stoichiometry optimization and strain engineering, an unprecedented PMA strength of ≈30 kJ m−3 for TmIG is achieved. This achievement demonstrates a simple and effective method for harnessing the magnetic properties of rare‐earth iron garnet films, paving the way for their advanced applications in next‐generation spintronic devices. [ABSTRACT FROM AUTHOR]

During geomagnetic storms, geomagnetically induced currents (GICs) occur in the power grid. GIC is a quasi‐direct current, which is represented by using a fixed DC current, the authors propose an approach that combines field‐circuit‐coupled and weakly coupled magneto‐mechanical models to investigate the magnetostriction characteristics of single‐phase, four‐column autotransformer cores excited by GICs. A non‐linear magnetostrictive constitutive model that considers the impact of stress and magnetisation intensity on ferromagnetic materials is introduced. The model reveals that the strain in the core initially increases as the magnetisation intensity increases; however, when the core begins to saturate, the magnetostrictive strain weakens as the magnetisation intensity increases. Moreover, the results of multiphysics finite‐element modelling are experimentally verified using a direct current bias platform. The results show that when excited by GICs, there is an enhancement in the vibration of the iron core, and the harmonic content of the vibration acceleration increases considerably, with the odd harmonics most significantly increasing in amplitude. The conclusion drawn is that GICs can exacerbate transformer vibration and significantly increase the content of harmonics, especially odd harmonics. [ABSTRACT FROM AUTHOR]

Principal-internal joint resonance of an axially moving beam with elastic constraints is investigated, where the beam is located in magnetic field excited by current-carrying wires. Based on the magnetoelasticity theory and Hamilton principle, the nonlinear magneto-elastic vibration equations are derived. The displacement function is obtained by the elastic constraint boundary condition, and then the equation is discretized into 2-DOF ordinary differential equations using the Galerkin integral method. The method of multiple scales is employed for obtaining the amplitude–frequency response equations with coupling of the first two vibration modes. Through examples, amplitudes varying with frequency tuning parameter, axial velocity, current intensity, and external excitation force are exhibited. Results indicate that as current intensity increases, electromagnetic damping increases and the amplitude decreases; As external excitation force increases and axial velocity decreases respectively, the amplitude increases and the system changes from single periodic motion to quasi-periodic motion and then to single periodic motion; The lower-order modes are always dominant when the principle-internal resonance occurs. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for the fabrication of magnetoelectric composites aimed at enhancing cross-coupling between electrical and magnetic phases for potential applications in intelligent sensors and electronic components. Unlike previous methodologies known for their complexity and expense, our method offers a simple and cost-effective assembly process conducted at room temperature, preserving the original properties of the components and avoiding undesired phases. The composites, composed of PZT fibers, cobalt (CoFe2O4), and a polymeric resin, demonstrate the uniform distribution of PZT-5A fibers within the cobalt matrix, as demonstrated by scanning electron microscopy. Detailed morphological analyses reveal the interface characteristics crucial for determining overall performance. Dielectric measurements indicate stable behaviors, particularly when PZT-5A fibers are properly poled, showcasing potential applications in sensors or medical devices. Furthermore, H-dependence studies illustrate strong magnetoelectric interactions, suggesting promising avenues for enhancing coupling efficiency. Overall, this study lays the basic work for future optimization of composite composition and exploration of its long-term stability, offering valuable insights into the potential applications of magnetoelectric composites in various technological domains. [ABSTRACT FROM AUTHOR]

The work is devoted to the theoretical investigation of the quasi-static magnetoelectric interaction in three-layer structures consisting of a piezoelectric and two magnetic layers with positive and negative magnetostriction. Using the system of elasto- and electrostatics equations for the piezoelectric and magnetostrictive phases, expressions for the electrical response of the structure in a magnetic field are obtained. The contributions from longitudinal and bending deformations are taken into account in value of ME interactions. It is shown that the use of an asymmetric three-layer asymmetric structure leads to an increase in the magnitude of the ME interaction by almost an order of magnitude compared to a two-layer structure. The dependences of the effect magnitude on the thickness of the third layer for the nickel/lead zirconate titanate/metglas structure are presented. [ABSTRACT FROM AUTHOR]

Abstract: The valve Reactor (VR) is an indispensable protective element within High Voltage Direct Current (HVDC) system converters, susceptible to malfunctions such as overheating and localized deformation under the conditions of ultra-high frequency and discontinuous operational excitation. This work provides a comprehensive review of the latest research findings on the electrical, thermal, and vibrational properties of VR. Initially, this work utilizes circuit models to analyze the constituent components of various VR types and their electromagnetic properties under actual working conditions, with a profound exploration of the insulation technologies involving epoxy resin and insulated silicon steel coatings. Subsequently, this work incorporates finite element analysis (FEA) on the basis of loss calculation models and conventional thermal circuit models to explain the temperature properties of VR from a multi-physics perspective. Furthermore, this work integrates mechanical calculation models with FEA models to elaborate on the vibrational properties of VR under practical excitations and discusses optimization measures. Finally, this work envisions the future development directions of VR from the perspectives of electrical, thermal, and vibrational properties, and proposes optimization suggestions, providing valuable references for the improvement of VR design and condition evaluation.

Unlike a typical spin–phonon coupling, an exhibition of unconventional spin–phonon coupling, which is mediated via magnetostriction effect, is reported in a hole-doped double perovskite Pr1.5Sr0.5CoMnO6. Various investigations including electronic and crystal structures, spin structure, transport property, lattice dynamics, and theoretical density of states analysis by density-functional theory (DFT) have been performed. A substantial increase in the mean oxidation states of Co ions and a concurrent abrupt decrease in the resistivity upon Sr doping is observed, thus altering its underlying transport mechanism. An insulating and ferromagnetic (FM) ground state is predicted by DFT calculations. The neutron diffraction data analysis reveals a complex crystal structure of Pr1.5Sr0.5CoMnO6, which consists of B-site disordered monoclinic (P21/n) and orthorhombic (Pnma) structures, highlighting the presence of an anti-site disorder in the system. The analysis also suggests an overall FM ordering of Co/Mn spins below 150 K for the monoclinic phase, whereas no such magnetic ordering is found for the orthorhombic phase. More interestingly, the neutron powder diffraction study perceives the presence of a strong magnetostriction effect in the system. Raman spectroscopy unravels the presence of a spin–phonon coupling, which is essentially mediated by the magnetostriction effect. [ABSTRACT FROM AUTHOR]

Spin wave propagation over long distances in confined ferromagnetic strip lines exhibiting magnetoelasticity opens up promising perspectives for device applications. Domain walls as natural spin wave channels increase the spin wave propagation distance. We calculate the magnetic and elastic modes through micromagnetic simulations and the dispersion relation of strip lines containing a Néel wall. We show that at the crossing points in the dispersion relation, two behaviors are observed: an anticrossing gap when a strong coupling is present or a gapless point when the magnetoelastic feedback cycle is not fulfilled. For the Néel wall-confined magnetic mode, the magnetic and elastic waves oscillate independently forming a gapless crossing point. For the domain modes, both behaviors are found. We discuss the gap existence based on the symmetry of the eigenmodes. [ABSTRACT FROM AUTHOR]

Using density functional theory calculation and rigid band model, we investigate the electronic structure and magnetostrictive properties of transition heavy-metal doped Fe-based (Fe–Al, Fe–Si, Fe–B, and Fe–Be) alloys. It is found that a small amount of addition of 4d/5d heavy-metal atoms greatly enhances the coefficient of tetragonal magnetostriction of Fe-based alloys, reaching up to about 1000 ppm in Fe87.5Al6.25Pt6.25 and Fe75Al18.75Rh6.25 alloys. The underlying mechanism is mainly ascribed to combined factors of band narrowing induced by non-bonded states in pure Fe layer, strong spin–orbit coupling effect by heavy metals, and improved mechanical properties, through analysis of the electronic density of states near Fermi level and k-mesh resolved magnetocrystalline anisotropy energy in momentum space. These results provide useful guidance for optimizing the magnetostrictive performance of Fe-based alloys for practical application. [ABSTRACT FROM AUTHOR]

The magnetostriction of Fe–Ga thin sheets can be significantly improved by secondary recrystallization, but the effect of the nano-heterogeneity on the magnetostriction of Fe–Ga thin sheets with preferred texture is still an open question. This paper studies the feasibility of tailoring nano-heterogeneity to enhance the magnetostriction of -oriented Fe–Ga thin sheets by aging treatment. The secondary recrystallization of Goss ({110}) texture with magnetostriction of 220 ± 12 ppm is achieved in Fe81Ga19 thin sheets after annealing at 950 °C. The magnetostriction and magnetic properties exhibit nonlinear changes with the increase of aging temperature. A peak magnetostriction of 244 ± 5 ppm is obtained in Fe81Ga19 thin sheets after aging at 450 °C, about 11% more than that of Fe–Ga thin sheets after secondary recrystallization. The effect of aging treatment on the magnetostriction of Fe–Ga thin sheets depends on the characteristics of the nano-scale L60 phase and causes lattice distortion. The increase of the volume fraction of the nano-scale L60 phase at the aging temperature of 450 °C leads to a much larger distortion and enhancement of the magnetostriction. As the aging temperature is lower than 400 °C or higher than 550 °C, the decrease of volume fraction or the coarsening of L60 phases, respectively, results in the decrease in the distortion of the A2 matrix.

Nickel doped CoMn ferrites with high magnetization were synthesized by double sintering solid state route with compositions of Co0.7-xNixMn0.3Fe2O4 with x = 0, 0.05, 0.1 and 0.15. Theoretical Cation distribution for cubic spinel ferrites was suggested on basis of electrical configuration expectations and cation site preferences. Cation distribution suggested was in good agreement with experimental results obtained from VSM and XRD. Values of theoretically calculated magnetic moment, coercivity and magnetization are in good agreement with experimental data obtained from VSM. Maximum saturation magnetization of 37.7emu/gm is obtained for sample Co0.7Mn0.3Fe2O4 at magnetic field of 5K Oe. Magnetostriction was found to increase with increasing magnetic field (from 1KOe to 5KOe.) Maximum magnetostriction of 84ppm was observed for sample Co0.7Mn0.3Fe2O4 at 5KOe. Maximum magnetization of magnetoelectric composites with 30% Co0.7-xNixMn0.3Fe2O4 – 70% PbZr0.48Ti0.52 was found to be 7.4 emu/g for composition with x = 0.

Abstract Tooth wear and pain are the primary concerns of patients undergoing periodontal scaling. The aims of this study were to compare the effects of a new magnetostrictive ultrasonic scaler and a traditional piezoelectric ultrasonic scaler on tooth surface roughness and calculus removal and to determine their impacts on patient discomfort during supragingival cleaning. This article had two parts: an in vitro study and a clinical study. In the in vitro study, thirty teeth with subgingival calculus were randomly assigned to two scaling treatment groups: magnetostrictive scalers (n = 15) and piezoelectric scalers (n = 15). Surface roughness measurements were taken at baseline and after scaling, and the root samples were visualised by SEM after scaling. Additionally, a single-centre randomised split-mouth clinical trial was conducted. Eighty-five participants diagnosed with chronic gingivitis or periodontitis were randomly assigned to receive supragingival scaling. The magnetostrictive scaler was used in half of the mouths (n = 85), and the piezoelectric scaler was used in the other half of the mouths (n = 85). Data on pain, noise, and vibration were collected using a VAS questionnaire, and the operating time was recorded. In both in vitro and clinical studies, magnetostrictive scalers were reported to be more effective than piezoelectric scalers in removing dental deposits (P

Fe–Ga alloys, containing 18, 21, and 23 at.% of Ga, were prepared in bulk form. In their as-cast state, they display a small magnetostriction, that is strongly improved after annealing at 1000 ° C for 24 h, and subsequent rapid cooling. Multiple characterization techniques, such as x-ray diffraction, differential scanning calorimetry, Mössbauer spectroscopy, temperature-dependent magnetization curves, hysteresis loops, magnetic force microscopy, and magnetostriction measurements, were exploited in synergy to gain a deep understanding of the structure–property relationships in the studied alloys, before and after annealing. The A2 phase, which is favored in the lower range of compositions and is promoted at the expense of the D 0 3 one by annealing, is responsible for characteristic dendritic and maze magnetic domains, and for the strong improvement of the magnetostriction, which almost reaches 240 ppm (transverse configuration) in the alloys with 18 at.% of Ga, after annealing. [ABSTRACT FROM AUTHOR]

AbstractReactors produce noise that negatively impacts the environment during their operation. This study focused on vibration and noise reduction in shunt oil reactors through an enhanced design, aiming to mitigate these environmental consequences. Additionally, the precision of measuring vibroacoustic characteristics was enhanced by employing the finite element method. This study utilized the 110–750 kV reactor, POM-60000/525-У1. To minimize noise and vibrations from the active part to the tank, the rubber gaskets’ thicknesses, dimensions, and placements were carefully chosen, considering the magnetic system’s design specifics and pressing forces within the reactor frame. The reactor’s design underwent improvements through modeling and optimization. In the revised design, the number of radiators in the cooling system on both sides and the stiffeners on the reactor tank’s walls were increased, while the reactor’s overall dimensions were preserved. The isosurfaces derived from vibroacoustic testing on the reactor tank model facilitated the processing and visualization of results, thereby validating the model’s accuracy and effectiveness. The average background noise levels of the enhanced reactor were significantly lowered, with the noise difference between the reactor and its surroundings being nearly double that of its existing counterpart. Since noise from wall vibrations and the cooling system impacts reactor lifecycles, reducing these vibrations is crucial for extending the lifespan of the improved reactor.

FeGa-based alloys are potential candidates in magneto-mechanical transversion applications. It has been demonstrated that doping with certain elements results in the increase in λ100 and modification of the texture, both of which effectively enhance the magnetostriction of FeGa. However, the contribution of each factor is difficult to distinguish because of lacking an effective physical model. In this work, based on the independence of saturation magnetostriction ( λ s ) on magnetic domain distribution, a paradigm that combines the orientation distribution function and magnetostriction tensor of single crystals is employed to quantify effects of texture on magnetostriction and predict λ100. Then this paradigm is applied to Ag-doped FeGa and the results reveal that the enhancement of λ100 plays a more crucial role in the enhancement of λ s after Ag doping. Our work clarifies the contribution to magnetostriction enhancement from texture and λ100 in element-doped FeGa alloys, and may help develop more high-performance FeGa alloys. [ABSTRACT FROM AUTHOR]

Magnetoelastic micro-electromechanical systems (MEMS) are integral elements of sensors, actuators, and other devices utilizing magnetostriction for their functionality. Their sensitivity typically scales with the saturation magnetostriction and inversely with magnetic anisotropy. However, large saturation magnetostriction and small magnetic anisotropy make the magnetoelastic layer highly susceptible to minuscule anisotropic stress. It is inevitably introduced during the release of the mechanical structure during fabrication and severely impairs the device's reproducibility, performance, and yield. To avoid the transfer of residual stress to the magnetic layer, we use a shadow mask deposition technology. It is combined with a free-free magnetoelectric microresonator design to minimize the influence of magnetic inhomogeneity on device performance. Magnetoelectric resonators are experimentally and theoretically analyzed regarding local stress anisotropy, magnetic anisotropy, and the ΔE-effect sensitivity in several resonance modes. The results demonstrate an exceptionally small device-to-device variation of the resonance frequency < 0.2% with large sensitivities comparable with macroscopic ΔE-effect magnetic field sensors. This development marks a promising step towards highly reproducible magnetoelastic devices and the feasibility of large-scale, integrated arrays. [ABSTRACT FROM AUTHOR]

We present a macroscale constitutive model that couples magnetism with thermal, elastic, plastic, and damage effects in an Internal State Variable (ISV) theory. Previous constitutive models did not include an interdependence between the internal magnetic (magnetostriction and magnetic flux) and mechanical fields. Although constitutive models explaining the mechanisms behind mechanical deformations caused by magnetization changes have been presented in the literature, they mainly focus on nanoscale structure–property relations. A fully coupled multiphysics macroscale ISV model presented herein admits lower length scale information from the nanoscale and microscale descriptions of the multiphysics behavior, thus capturing the effects of magnetic field forces with isotropic and anisotropic magnetization terms and moments under thermomechanical deformations. For the first time, this ISV modeling framework internally coheres to the kinematic, thermodynamic, and kinetic relationships of deformation using the evolving ISV histories. For the kinematics, a multiplicative decomposition of deformation gradient is employed including a magnetization term; hence, the Jacobian represents the conservation of mass and conservation of momentum including magnetism. The first and second laws of thermodynamics are used to constrain the appropriate constitutive relations through the Clausius–Duhem inequality. The kinetic framework employs a stress–strain relationship with a flow rule that couples the thermal, mechanical, and magnetic terms. Experimental data from the literature for three different materials (iron, nickel, and cobalt) are used to compare with the model's results showing good correlations. [ABSTRACT FROM AUTHOR]

This study used DC magnetron sputtering technology to fabricate Sm-Fe films and systematically investigated the phase transition behavior of Sm-Fe films with different Fe ratios. It was found that at higher Fe content, the films consisted of Sm2Fe17 or SmFe7 phases; as Fe content decreased, the films were mainly composed of SmFe3 or SmFe2 phases; at higher Sm content, the films primarily consisted of Sm phase. Sm is prone to volatilization at high temperatures, so Ta was used as a capping layer to effectively suppress Sm volatilization, successfully synthesizing pure SmFe2 phase films at a nearly 1:2 ratio. The magnetic properties and magnetostrictive behavior of the SmFe2 films were investigated, revealing that pure-phase SmFe2 films exhibit good perpendicular magnetic anisotropy and magnetostriction properties. The larger stress along the perpendicular-to-film direction, resulting from the absence of substrate-induced constraints, contributes to the excellent perpendicular magnetic anisotropy of the films. This study successfully synthesized pure-phase SmFe2 films and discovered a new method for fabricating perpendicularly anisotropic films. The research findings are of great significance for the efficient synthesis of desired films with high phase formation temperatures containing volatile elements. [ABSTRACT FROM AUTHOR]

The effect of ionic radii sizes on magnetostriction is studied in relation to structural and magnetic properties. To explore the effect of the chemical pressure, nanoparticles of rare‐earth (RE) orthoferrites, SmFeO3, DyFeO3, HoFeO3, and LuFeO3 are studied using X‐ray diffraction, field emission scanning electron microscopy, and Raman spectroscopy. Magnetic and magnetostriction measurements are also performed. In these orthoferrites, the coordination of the RE ion is eightfold, whereas the RE ionic radii are significantly different, which directly influences the structural parameters. The distortion of FeO6 octahedra is observed as a result of changing chemical pressure within the lattice. The different magnitudes of magnetostriction in RE orthoferrites can be attributed to the different degrees of distortion of FeO6 octahedra, R–O dynamics, and spin–orbit interactions in the system. The maximum value of magnetostriction (∼ 19 ppm) and magnetization at 2 K (30.64 emu/g) is demonstrated by HoFeO3. Comparison of structural parameters of the samples to their respective bulk counterparts indicated relative structural distortion in nanoparticles. [ABSTRACT FROM AUTHOR]

Accurate measurement of magnetostriction is the basis for calculating the vibration of silicon steel laminated core. In this paper, a laser magnetostriction measurement system (MST500) is used to study the magnetostriction characteristics of silicon steel under sinusoidal, third harmonic, and DC bias magnetization. The magnetostrictive butterfly curves, time domain waveforms, and spectrum diagrams of silicon steel sheets under different excitations are compared and analyzed. The effects of different operating conditions on the magnetostrictive properties of silicon steel sheets were studied and analyzed, mainly including amplitude and spectrum analysis. Finally, the magnetostrictive peak to peak curves under different operating conditions were extracted, providing a data basis for the core vibration of power equipment. [ABSTRACT FROM AUTHOR]