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An air gap Fabry–Perot fiber interferometric magnetic field sensor based on magnetostrictive effect is proposed. The sensor is composed of single mode fiber (SMF), silica capillary and magnetostrictive material, forming the Fabry–Perot cavity of "single mode fiber-air gap-single mode fiber". With the change of external magnetic field, the magnetic volume of magnetostrictive material changes, the length of gas chamber changes, resulting in the change of optical path difference. Therefore, changes in the magnetic field can be obtained by monitoring the wavelength of the reflection spectrum. Within the magnetic field range of 3.68mT-5.72mT, the magnetic field sensitivity and linearity of the sensor are 0.299 nm/mT and 0.99767, respectively. In addition, temperature changes can also affect the sensor. At 51–56 °C, its temperature sensitivity is 0.163 nm/°C, and its linearity is 0.99831. The temperature cross sensitivity coefficient of the sensor is 0.545mT/℃. This simple, low-cost, and high-performance sensor is a promising candidate for magnetic field monitoring. [ABSTRACT FROM AUTHOR]

For realizing ultrasonic elliptical vibration-assisted cutting, a single excitation elliptical vibration system was proposed in this work, which was composed of a giant magnetostrictive transducer and an asymmetrical stepped ultrasonic horn with arc transition (ASUH). The dynamic simulation of the vibration system was carried out using ANSYS, the output end of the vibration system produced longitudinal and transverse vibrations simultaneously due to the ASUH at the resonant frequency, and the influence of the transition arc of the ASUH on the elliptical vibration performance of the vibration system was studied. The impedance, elliptical vibration trajectory of the output end, and output amplitude of the vibration system were tested experimentally. The results show that the actual resonant frequency of the vibration system was 20.708 kHz, the mechanical quality factor was 106, and the longitudinal amplitude was slightly greater than the transverse amplitude of the output end. The theoretical calculations coincide with the experimentally tested results. [ABSTRACT FROM AUTHOR]

In recent years, ultrasonic machining has been developing rapidly, and it is used in areas such as abrasive machining, cleaning, and welding. In this research, a magnetostrictive device with pure nickel conical core with cone angle of 30° was constructed. The observed sound pressure level was used as a measure of transducer performance. Also, the ability of the device to reduce the residual pesticide on cucumber surface due to cavitation was evaluated. The results showed that the sound pressure from simulation by JMAG-Designer software is almost the same as the sound pressure produced in the constructed transducer. To assess the performance of the device in removing residual pesticide from cucumber surface and evaluate the changes in peel texture of cucumber, the gas chromatography (GC) and scanning electron microscope (SEM) methods were used, respectively. The GC results showed that with 20 min treatment, the removal of pesticide based on height and chromatogram area was 75% and 83%, respectively. The SEM results showed that by increasing the treatment time, the stomatal pore area reduced from 144.74 μ m 2 (reference) to 30.56 μ m 2 (20 min treatment). These results are promising; hence, further research is suggested towards enhancing the device for commercial use in biomaterials processing operations such as cleaning and removing pesticides from fruits and vegetables. [ABSTRACT FROM AUTHOR]

A numerical study of the delay in the excitation of oscillations of a magnetostrictive transducer in the frequency multiplication mode based on the model of coupled oscillators is presented. The non-stationary nature of the oscillations excited after the amplitude jump is revealed. The phenomenon is interpreted on the basis of the dynamic potential model. A numerical study of the development of oscillations in time has been carried out, and phase portraits of oscillations have been constructed. The fractal-like nature of non-stationary oscillations is established, which manifests itself in the preservation of the degree of their chaoticity with a change in the value of the calculation step in time. [ABSTRACT FROM AUTHOR]

The article addressed the heat exchange efficiency of an antifreeze flow, used as the working substance in a refrigeration system and filled with a magnetostrictive intermetallic alloy. A dynamic two-dimensional gradient magnetic field was employed as a propulsion source for the magnetostrictive coolant. The regulation and control of the volume flow rate of the coolant were achieved by inducing the dynamic magnetic field, which influenced the orientation and size of the scale-shaped particles dispersed within the coolant. Replacing conventional pumps with magnetic field-based propulsion systems for the circulation of antifreeze in heat-exchange systems offers a reduction in energy consumption in technological systems. [ABSTRACT FROM AUTHOR]

In this work, the mask method is applied to design a variety of topological structures in the magnetic layer. Different topological Mo/FeGa/AlN magnetoelectric (ME) devices were fabricated. Controlling the stress conduction mode between the magnetostrictive phase and the piezoelectric phase is one of the goals that enables the coexistence of normal stress and shear stress. In order to improve the ME performance of devices, the second purpose is to induce the ME anisotropy of devices through the magnetostrictive anisotropy caused by the topological structure. The circular topological Mo/FeGa/AlN devices produce the largest ME coupling coefficient along the length direction (7071 mV/cm Oe), which is 1.84 times higher than that of the planar devices (3853 mV/cm Oe). The maximum ME anisotropy coefficient (4.612) is determined from the strip topology ME device, which is 2.45 times higher than that of the planar device. [ABSTRACT FROM AUTHOR]

We study steady-state three bipartite entanglements in a cavity magnomechanical system which is composed of magnon, two cavities, and mechanical resonator. The two cavities are connected by an optical fiber, one of cavities couples to the magnon via the magnetic dipole interaction, at the same time, the magnon couples to the mechanical resonator via magnetostrictive interaction. Making use of logarithmic negativity, magnon, cavity, and mechanical resonator are entangled with each other by selecting appropriately the parameter. We find that the steady-state entanglements in the magnon–mechanical resonator subsystem and in the magnon–cavity subsystem are very sensitive to the effective magnomechanical coupling strength. Moreover, the entanglement is robust with respect to the certain environment temperature. [ABSTRACT FROM AUTHOR]

Air-coupled ultrasonic excitation is a relatively poorly studied method of nondestructive testing of polymer and composite materials. The combination of noncontact ultrasonic stimulation in conjunction with laser vibrometry can provide an assessment of the quality of the product without external influence on the tested material. This work is devoted to the study of an ultrasound diagnostic system based on the combined use of a noncontact magnetostrictive transducer and scanning laser Doppler vibrometry for nondestructive testing of polymer and composite materials. We believe that such combination can provide sufficient power for rapid detection of defects, while the optimization of the experimental conditions increased the efficiency of testing results. Measurement of the directional diagram of the magnetostrictive transducer has made it possible to determine the features of the radiation of the magnetostrictor in an assembly with a titanium step-type waveguide. [ABSTRACT FROM AUTHOR]

Delta-E effect sensors are based on magnetoelectric resonators that detune in a magnetic field due to the delta-E effect of the magnetostrictive material. In recent years, such sensors have shown the potential to detect small amplitude and low-frequency magnetic fields. Yet, they all require external magnetic bias fields for optimal operation, which is highly detrimental to their application. Here, we solve this problem by combining the delta-E effect with exchange biased multilayers and operate the resonator in a low-loss torsion mode. It is comprehensively analyzed experimentally and theoretically using various kinds of models. Due to the exchange bias, no external magnetic bias fields are required, but still low detection limits down to 350 pT / Hz at 25 Hz are achieved. The potential of this concept is demonstrated with a new operating scheme that permits simultaneous measurement and localization, which is especially desirable for typical biomedical inverse solution problems. The sensor is localized with a minimum spatial resolution of 1 cm while measuring a low-frequency magnetic test signal that can be well reconstructed. Overall, we demonstrate that this class of magnetic field sensors is a significant step towards first biomedical applications and compact large number sensor arrays. [ABSTRACT FROM AUTHOR]

Because the performance of giant magnetostrictive materials (GMMs) can vary at different temperatures, the positioning accuracy of a giant magnetostrictive actuator is affected by heat. In this work, a new simplified control strategy under compulsory water cooling is proposed to maintain a constant GMM temperature. Based on this strategy, a coupled turbulent flow field and temperature field finite element model is created for a GMM smart component. The model is simulated using COMSOL Multiphysics software version 5.3. Through simulations, the temperature field distribution of GMM smart components is analysed under different drive input currents and cooling water flow rates. Based on the obtained simulation results, a GMM intelligent component temperature control device is constructed. The experimental results are in good agreement with the simulation results; a thermostatic control effect is achieved in the thermostat of the giant magnetostrictive rod. Thus, the proposed temperature control strategy is proven effective via simulations and experiments. [ABSTRACT FROM AUTHOR]

The magneto-mechanical effect combines the magnetic field and stress σ, making it an important approach for detecting stress concentration and microscopic failure in electrical machines. Alloy sheets as Fe-Si3% used in mechanical structures are subject to the effect of both magnetic and mechanical constraints, but the effects of a mechanical stress on this type of alloy are not widely considered. In previous work, a theoretical approach was proposed, which was obtained by incorporating, in the classical effective field model given by Jiles-Atherton (JA), the effect of an equivalent stress demagnetizing field denoted Hdϭ. Presence of this parameter explains the asymmetry in the change of magnetization under the conditions of tensile and compressive stress. Stress concentration affects all properties of the material. The intermolecular interaction inside the sheet defined by the classical domain coupling factor α is one of more parameters which is affected and need to be modeled. This paper proposes to elaborate a new model based on the merits of the previous approach. An accurate model denoted αeff is thus developed. The evolution of αeff and the magnetostrictive behaviors are simulated at an average frequency f = 50 Hz under tensile stresses. The obtained results are compared with some reported ones; the tendency is shown to be in concordance with those published. [ABSTRACT FROM AUTHOR]

In this paper, a vibrational drilling tool using a magnetostrictive torsional transducer is designed and fabricated. The torsional transducer is a hollow cylinder, which is made up of "2 V permendur." Passing an alternating current through the material creates a variable circular magnetic field and exciting a coaxial coil with a direct current generates a constant axial field in the material. According to the Wiedemann effect, the magnetic domains of the material rotate helically in the direction of the external field and cause a shear strain in the material. To utilize the maximum torque and amplitude of the transducer as well as to maintain the transducer's resonance conditions, a wave transmitter is designed to connect the transducer to a drill bit. The dimensions of the vibrating tool are calculated theoretically and verified by the finite element software of COMSOL. Friction couplings are designed to connect the transducer, wave transmitter, and the drill bit. This torsional drilling tool is used for drilling of aluminum workpieces. The tests show that torsional vibrations reduce the required drilling torque by 60% in comparison to conventional drilling. In addition, usage of the torsional vibrations has the effect of the chip breaking, improving the accuracy of the hole size by 55.4%, and reducing the drilling surface roughness by the percent of 25.3% in comparison to conventional drilling. [ABSTRACT FROM AUTHOR]

Tb–Dy–Fe–Co thin films grown on Si 100 substrates at different substrate temperatures viz., room temperature, 300, 400 and 500 °C were investigated for structural, microstructural, magnetic and magnetostrictive properties. Grazing incidence X-ray diffraction studies showed presence of amorphous structure for the as-deposited film. Structural studies further indicated formation of (Tb,Dy)2(Fe,Co)17 and Fe–Co phases for the films grown at higher substrate temperatures. Magnetization measurements displayed presence of strong in-plane magnetic anisotropy for all the films. In addition to this, formation of out-of-plane magnetic anisotropy co-existing with in-plane magnetic anisotropy was noticed for the films grown at higher substrate temperatures. Accordingly, magnetic force microscopy studies indicated a strong out-of-plane magnetic contrast for the films grown at higher substrate temperatures. The magnetostriction estimated from tip deflection measurement was found to be negligibly small for the film grown at intermediate temperature viz., 300 °C. However, with subsequent increase in substrate temperatures the magnetostriction was found to increase. The presence of strong out-of-plane magnetic anisotropy co-existing with in-plane components was found to be detrimental for the development of magnetostriction. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) coupled magneto-elastic dynamic model of a giant magnetostrictive actuator (GMA) was built based on Maxwell’s equations, elasticity, and vibration theories. The general analytical expressions for the 3D internal magnetic field distribution of GMA were derived, and the corresponding analytical solutions were obtained. This analytical model is able to predict the internal magnetic field distribution and the output displacement of GMA system with different physical parameters under external excitations. The dynamic behaviors, such as the amplitude vs. frequency responses and the time domain waveforms of the GMA, were also studied. Analytical solutions showed that the internal magnetic field has a prominent end effect along the axial direction of a giant magnetostrictive material (GMM) rod, whereas a minimal skin effect along its radial direction, which are matched very well with the FEM results. The amplitude-frequency relationship exhibited prominent resonance and anti-resonance characteristic, which is a typical hysteresis feature of the GMA system. In order to testify the validity of the model prediction, a GMA testing system was also established. Excellent agreement was found between the experiment measurements and model predictions in the range of our research (frequency is lower than 300 Hz). The analytical results of the present study have potential applications in the fields of active vibration control and other precision machining of the GMA system. [ABSTRACT FROM AUTHOR]

Active vibration control to suppress structural vibration of the flexible structure is investigated based on a new control strategy considering structure-actuator interaction. The experimental system consists of a clamped-free rectangular plate, a controller based on modal control switching, and a magnetostrictive actuator utilized for suppressing the vibrations induced by external excitation. For the flexible structure, its deformation caused by the external actuator will affect the active control effect. Thus interaction between structure and actuator is considered, and the interaction model based on magnetomechanical coupling is incorporated into the control system. Vibration reduction strategy has been performed resorting to the actuator in optimal position to suppress the specified modes using LQR (linear quadratic regulator) based on modal control switching. The experimental results demonstrate the effectiveness of the proposed methodology. Considering structure-actuator interaction (SAI) is a key procedure in controller design especially for flexible structures. [ABSTRACT FROM AUTHOR]

These linear actuators with large displacement, high resolution and compact structure have played an important role in ultra-precision engineering and still attracted a lot of attentions for various applications. Thus, a new integrated linear actuator with above capacities, based on the principle of coarse-fine composite, is proposed and discussed in this paper. Owing to the integration of a new electromagnetic rotor drive (ERD) and a smart giant magnetostrictive drive (GMD), a larger displacement can be initially achieved and maintained by the driving of the ERD, whereafter a smaller displacement can be adjusted and refined by the GMD. The mechanism structure and working principle are presented and described detailedly. As the key part, mechanical analysis and dynamic modeling of the ERD are carried out and established, and structure optimization is also conducted for obtaining a better working environment. A prototype was manufactured and its main performance was tested through a series of experiments. The results confirm that with a compact size of $$\phi43 \times 95\, {\text{mm}}\, (L)$$ the maximum output displacement is 503 μm, and the movement resolution is up to 70 nm, proving the feasibility of precise positioning in ultra-precision engineering. [ABSTRACT FROM AUTHOR]

Composite structures which show magneto-electric (ME) coupling behavior have a wide range of engineering applications. In this work, a composite structure comprising of a ferroelectric and a magnetostrictive material is taken for investigation. First, the nonlinear responses of the ferroelectric material and the magnetostrictive material are studied separately by experiments. In order to predict the nonlinear response, a thermodynamically consistent macroscopic model is proposed for the ferroic materials. Model parameters are then estimated from the experimental data, and the simulated results based on the proposed model are presented. Results from the theoretical model are in agreement with the experimental data. Subsequently, a homogenization procedure is introduced to find out the nonlinear response of a layered ME composite structure, and the obtained results are discussed. [ABSTRACT FROM AUTHOR]

The nonlinear dynamic characteristics of Fe-Ga cantilever nanobeam subjected to stochastic excitation are studied in this paper where the nonlocal effect is considered. Nonlinear differential terms are introduced to explain the hysteretic phenomena of the Fe-Ga alloy's strain-magnetic field intensity curves, and the nonlinear dynamic model of Fe-Ga cantilever composite nanobeam subjected to stochastic excitation is developed. The system's nonlinear dynamic characteristics are discussed, and the optimal control strategy is proposed to enhance the system's reliability. Numerical simulations show that the nonlocal effect can influence the system's stochastic Hopf bifurcation; the boundary of the system's safe basin has fractal characteristics, the area of safe basin decreases when the intensity of the noise increases, and it increases again through stochastic optimal control. The results of this study are helpful for the application of Fe-Ga composite nanobeam in engineering fields. [ABSTRACT FROM AUTHOR]

Magnetostrictive materials that may alter their shape significantly in response to external magnetic fields are used in unidirectional motion and force actuators and linear motors. In this study, we present a linear magnetostrictive motor (LMM) powered through a pulse width modulation (PWM) drive, whose core is a waveform controller of DRV101T type. Mathematical modeling and numerical simulations (in the finite element method) are used in the design phase to optimally size the LMM and to predict its behavior in stationary and dynamic working conditions, for a duty cycle (percentage of time when the driving coil is active) $$k=70$$ % and the frequency $$f=1$$ kHz. The mechanical bias, provided by a spring system, is complemented with a bias coil, which is powered by a PWM stage too. This solution provides for enhanced and flexible control, while reducing the Joule losses to a minimum. LMM actuation is also provided through a second coil. The frequency of the voltage applied to the actuation coil is the same with the frequency of voltage applied to the bias coil. The concept of the LMM drive and its construction are validated through interferometry, vibration and thermal imager measurements. [ABSTRACT FROM AUTHOR]

A novel mass sensor resonator in anti-resonance mode to detect the particles in the order of picogram is proposed. The model is a cantilever beam composed of a PZT-5A layer as readout and Metglas 2605SC as a magnetostrictive material. The cantilever beam is exposed to harmonic magnetic field; once the Metglas experiences the magnetic field, undergoes mechanical strain and as a result the PZT-5A gives off electrical potential difference throughout the output circuit. The governing motion equations in the presence of the added distributed mass is derived and numerically integrated over the time. The voltage frequency response curves are determined. The results reveal that for small enough external loads in the output circuit between two successive natural frequencies, there exist an anti resonance region where the steady state response amplitude dramatically drops. Once the added mass is deposited on the micro beam the frequency response curve is shifted along the frequency domain and as a result the response amplitude suddenly jumps which is used as a measure of the added mass. [ABSTRACT FROM AUTHOR]

Magneto polymer matrix composites (MPMC) is a new class of magnetic polymer materials which are being developed and under investigation as potential materials for tomorrow’s aircraft structures. It encompasses magnetic, particulate strengthening (dispersion strengthening) as well as fiber reinforcement/strengthening characteristics which are sought out to be utilized toward making efficient future aerospace composite materials. Various types of ferrites including barium, cobalt, iron, and strontium were explored for being used in making new composites. Here a comprehensive review of the synthesis, structure, properties, thermodynamics, surface chemistry, and phase transformations of individual ferrites and clusters of ferrites as fillers is presented. In particular a discussion about the rational control of the mechanical, physical, thermal, electrical, and magnetic properties of magneto polymer matrix composites through surface functionalization, modification, emulsification/compounding/blending, heat treatment (phase transformation and separation), and control of processing conditions (temperature, pressure and geometry of mold) is provided. These smart materials have a wide range of potential applications in medicine, drug delivery, bio imaging, bio marking, tissue engineering, electromagnetic interference (EMI) and electromagnetic force (EMF) shielding, and as competent materials for aerospace structural applications. [ABSTRACT FROM PUBLISHER]

Of the many existing inspection or monitoring systems, each has its own advantages and drawbacks. These systems are usually comprised of semi-remote sensors that frequently cause difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites, so that embedding can be achieved in virtually any component part and periodically can be interrogated by a reading device. The 'reinforcement rich' processed areas can then be used to record properties such as strain, temperature, and stress state, to name a few, depending on the reinforcement material. Friction stir processing was used to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum matrix. The aim was to develop a composite that produces strain in response to a varying magnetic field. Reinforcements were distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer. A simple and cost-effective setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and the processing route was modified to improve the magnetic response. [ABSTRACT FROM AUTHOR]

We suggest a new hysteresis model that can describe rate and bias effects of the harmonic magnetic fields on hysteresis nonlinearities of a magnetostrictive actuator. The proposed model is constructed using the generalized rate-dependent Prandtl-Ishlinskii model that incorporates a rate-bias-dependent threshold and a memoryless functions. The results show that the proposed model can characterize the asymmetric hysteresis effects under different levels of input magnetic bias which are applied at different excitation frequencies. [ABSTRACT FROM AUTHOR]

The theoretical and experimental investigation of the direct magnetoelectric effect in the ring-type structures made of the bulk magnetostrictive-piezoelectric composites has been presented. The analytical expression for the magnetoelectric voltage coefficient has been obtained using the effective parameters method. The frequency dependence of this parameter is also analyzed. The dependence of the resonant frequency and the amplitude of this effect of the geometrical parameters of the ring for the first and second oscillation modes are presented. The experimental investigation of the direct magnetoelectric effect for the ring-type composite specimens consisting of the nickel ferrite spinel-PZT bulk composite is done. The obtained experimental data are in good agreement with the theoretical predictions. [ABSTRACT FROM AUTHOR]

The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the strain-induced anisotropy resulting from the anisotropic thermal expansion of the β-phase PVDF. The simulation based on modified Stoner-Wohlfarth model and the ferromagnetic resonance measurements confirms our results. The positive temperature coefficient of magnetic anisotropy is estimated to be 1.1 × 102 J m-3 K-1. Preparing the composite at low temperature can enlarge the temperature range where it shows the positive temperature coefficient of magnetic anisotropy. The present results may help to design magnetic devices with improved thermal stability and enhanced performance. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to investigate the biofilm removal capacity of two ultrasonic tips under standardized conditions using a multi-species biofilm model. Methods: Six-species biofilms were grown on hydroxyapatite discs for 64.5 h and were treated for 15 s with a standardized load of 40 g with a piezoelectric or magnetostrictive device. Tips were applied either with the tip end or with the side facing downwards. Detached bacteria were determined in the supernatant and colony-forming units (CFUs) counted after 72 h of incubation. Untreated specimens served as controls. Moreover, the biofilms remaining on the hydroxyapatite surface after treatment were stained using the Live/Dead stain, and the pattern of their detachment was assessed by confocal laser scanning microscopy (CLSM). Results: As compared to the untreated control, it was found that only a side application of the magnetostrictive device was able to remove efficiently the biofilm. In contrast, its tip application as well as both applications of the piezoelectric device removed significantly less bacteria from the biofilm structure. These findings were corroborated by CLSM observation. Conclusion: Both ultrasonic tips under investigations led to bacterial detachment, but the action mode as well as the tip configuration and adaptation appeared to be influenced by the biofilm removal effectiveness. Clinical relevance: Biofilm removal remains a main goal of ultrasonic debridement. This should be reflected in respective laboratory investigations. The presented combination of methods applied on a multi-species biofilm model in vitro allows the evaluation of the effectiveness of different ultrasonic scaler applications. [ABSTRACT FROM AUTHOR]

This paper proposes a pitch error compensation technique with decomposition of mechanical signals based on giant magnetostrictive actuator (GMA) to eliminate tool tracking errors and to reach a high machining precision. In ultra-precision cutting, grinding and nontraditional machining, there is a difficult problem for achieving long travel and high precision. Considering the characteristics of giant magnetostrictive materials (GMM), a micro-displacement GMA with a flexure hinge micro-motion table is designed, and used for error compensation. The inherent hysteresis nonlinearity of the GMA is controlled effectively by a sliding mode robust adaptive controller (SMC). Aiming at reducing the positioning error of a precision working table driven by an AC servo motor, the measurement of the dynamical characteristics of the system is carried out by a laser interferometer. The leadscrew pitch error, which accounts for most of the error detected, is separated out by an improved signal filter algorithm. Experimental results show that the positioning error is reduced to an extent within ±8 μm from ±20 μm after compensation, which demonstrates the feasibility of the control and compensation method. [ABSTRACT FROM AUTHOR]

We have studied a magnetoelectric (ME) effect that is nonlinear with respect to the alternating magnetic field. It is established that resonance excitation of an alternating electric field takes place in magnetostrictive-piezoelectric bilayer structures under the action of alternating magnetic field at a frequency that is half as small as the electromechanical resonance frequency. The nonlinear ME effect, in contrast to the linear one, does not depend on the constant (magnetizing) bias field and is quadratic with respect to the alternating magnetic field. [ABSTRACT FROM AUTHOR]

New metal-polymer composites based on mechanochemically synthesized magnetostrictive Fe-Ga phase particles with dimensions of up to 2 μm dispersed and spatially oriented in a polymer matrix have been studied. The polymer matrix for spatial anisotropic stabilization of particles was represented by modified polyurethane (PU). An increase in the magnetostrictive effect was achieved by directed orientation of particles in a magnetic field applied during polymerization of the PU matrix. The spatial anisotropy of the composite has been studied by the methods of conversion Mössbauer spectroscopy with resonant X-ray detection and scanning electron microscopy. It is shown that the mechanochemical synthesis is an effective method of obtaining particles with microstress-enhanced magnetostriction. The use of these particles for the formation of a functional elastomer composite provides a material with significant magnetostrictive effect, which can be several-fold increased due to orientation of particles in an applied magnetic field. The obtained anisotropic magnetostrictive composite is a promising material for the creation of smart functional components of positioning systems, attenuators, and sensors. [ABSTRACT FROM AUTHOR]

A theory of the magnetoelectric effect in a bilayer magnetostrictive-piezoelectric structure is presented. As objects of research, structures in the form of nickel-lead zirconate-titanate and permendur-lead zirconate-titanate based plates are chosen. Joint solution of the motion equation for a magnetostrictive and piezoelectric medium and of the constitutive equations yields an expression for the magnetoelectric voltage coefficient in the region of electromechanical resonance. [ABSTRACT FROM AUTHOR]

A binary switch is the basic building block for information processing. The potential energy profile of a bistable binary switch is a 'symmetric' double well. The traditional method of switching it from one state (one well) to the other is to tilt the profile towards the desired state. Here, we present a case, where no such tilting is necessary to switch successfully, even in the presence of thermal noise. This happens because of the built-in dynamics inside the switch itself. It differs from the general perception on binary switching that in a 'symmetric' potential landscape, the switching probability is 50% in the presence of thermal noise. Our results, considering the complete three-dimensional potential landscape, demonstrate intriguing phenomena on binary switching mechanism. With experimentally feasible parameters, we theoretically demonstrate such intriguing possibility in electric field induced magnetization switching of a shape-anisotropic single-domain magnetostrictive nanomagnet with two stable states at room-temperature. [ABSTRACT FROM AUTHOR]

[TbFe( x nm)/FeCoV( y nm)] multilayers were prepared by multitarget magnetron sputtering using a rotary turn-table technique in a stop-and-go mode. The multilayers were investigated using X-ray diffraction, field emission scan electron microscopy and vibrating sample magnetometry. The result shows that the coercive field drops abruptly with increasing number of bilayers, and it remains generally stable when the number of bilayers is 10 or higher. An excellent magnetic softness with a coercivity of 1.0 mT is obtained for x = 5 and y = 5 after annealing at 250°C. A crystalline state is observed in FeCoV layers before and after annealing by X-ray diffraction. [ABSTRACT FROM AUTHOR]

We have theoretically and experimentally studied the direct magnetoelectric (ME) effect in ring structures made of volume ferrite-piezoelectric composites based on lead zirconate titanate and nickel ferrite. Analytical expressions for the ME voltage coefficient are obtained by jointly solving elastodynamic and electrostatic equations. Results of theoretical calculations and experimental measurements for various geometric parameters of the ring structures are presented. [ABSTRACT FROM AUTHOR]

The coupling between electric, magnetic and elastic features in multiferroic materials is an emerging field in materials science, with important applications on alternative solid-state cooling technologies, energy harvesting and sensors/actuators. In this direction, we developed a thorough investigation of a multiferroic composite, comprising magnetocaloric/magnetostrictive Gd 5 Si 2.4 Ge 1.6 microparticles blended into a piezo- and pyroelectric poly(vinylidene) fluoride (PVDF) matrix. Using a simple solvent casting technique, the formation and stabilization of PVDF electroactive phases are improved when the filler content increases from 2 to 12 weight fraction (wt.%). This effect greatly contributes to the magnetoelectric (ME) coupling, with the ME coefficient α M E increasing from 0.3 V/cm.Oe to 2.2 V/cm.Oe, by increasing the amount of magnetic material. In addition, magnetic measurements revealed that the ME-coupling has influenced the magnetocaloric effect via a contribution from the electroactive polymer and hence leading to a multicaloric effect. These results contribute to the development of multifunctional systems for novel technologies. [ABSTRACT FROM AUTHOR]

The article reports on a study magnetotransport of electrons by Zuanming Jin and co-workers from Germany and Portugal, which found that ultrafast terahertz spectroscopy can unamboguously quantify the fundamental parameters of electron magnetotransport.

A correction to the article "Fe73.5Cu1Nb3Si15.5B7 Thin Films Deposited by HiPIMS: Magnetic and Magnetostrictive Behavior" that was published in the November 14, 2014 issue is presented.