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Perpendicular magnetic anisotropy (PMA) in magnetic thin films has attracted much attention due to its potential applications in spintronics devices. Here, we report the continuous strain-mediated PMA in epitaxial (111) CoFe 2 O 4 (CFO) thin films grown on (0001) LiTaO 3 substrates. A large variation in lattice strain (∼ 0.9 %) in a continuous way is realized in the CFO thin films by changing substrate temperature during deposition due to the difference in the thermal expansion coefficient between CFO and LiTaO 3. As a result, the PMA of the (111) CFO thin films can be continuously mediated by the strain with uniaxial magnetic anisotropy energy in the range of 0.12 - 14.69 × 10 6 erg/cm 3. Furthermore, the strain as well as the consequent PMA in the (111) CFO thin films can be maintained within the thickness of 25–205 nm, which is consistent with the scenario of the magnetoelastic effect. Our results reveal that the CFO/LiTaO 3 system can be regarded as an ideal platform to realize robust PMA and its continuous strain tuning in the (111) CFO thin films by virtue of strain-induced magnetic anisotropy. [ABSTRACT FROM AUTHOR]

Magnetoelastic biosensors have emerged as a promising technology for the sensitive and label-free detection of a wide range of biological analytes. These biosensors use the magnetoelastic effect, which describes how the mechanical properties of magnetostrictive materials change in response to a magnetic field. This effect is utilized to detect biological analytes by immobilizing specific recognition elements, such as antibodies or nucleic acids, on the magnetoelastic material's surface. The binding of target analytes to the recognition elements induces a mass change, leading to a shift in the resonance frequency of the magnetoelastic material. Magnetoelastic biosensors find applications across various fields, including medical diagnostics, environmental monitoring, and food safety. In medical diagnostics, they offer rapid and sensitive capabilities for detecting pathogens, biomarkers, and toxins. For environmental monitoring, they demonstrate the ability to detect pollutants and heavy metals. Furthermore, in ensuring food safety and quality, magnetoelastic biosensors detect allergens, pathogens, and contaminants effectively. Ongoing research and technological advancements suggest that these biosensors hold great potential for revolutionizing various fields, including healthcare, environmental monitoring, and food safety, contributing to improved disease diagnosis, environmental protection, and public health. This review article provides an overview of the principles, fabrication methods, diagnosis, bacterial density, food, and agricultural applications of magnetoelastic biosensors. [ABSTRACT FROM AUTHOR]

AbstractThe present paper discusses experimental results concerning the deformation-induced generation of electric potential difference in steel specimens. According to our observations, voltages in the order of 10 microVolts can be measured between points on the surfaces of steel bodies during mechanical deformation. Three different experimental set-ups were used to determine the properties of the phenomenon, carefully excluding the influence of possible external electromagnetic fields. In order to exclude thermoelectric effects, a special steel specimen was fabricated. Further experimental campaigns were conducted with long, thin metallic rods in two different set-ups: the generation of voltage was measured during the traveling of longitudinal shock waves and during bending vibrations of the specimens. The results indicate that the variation of the magnetization of the material – the magnetoelastic effect – plays an important role in the phenomenon, but thermoelectricity also contributes to the measurable voltage signals. The electromechanical effect identified in the present paper may have several applications in measurement technology. The most relevant advantage of the applied measurement methods is that these are essentially sensor-free, since the mechanical vibrations can be detected by simply soldering, welding, or pressing copper wires to the examined steel specimen. [ABSTRACT FROM AUTHOR]

We investigate the relationships between various magnetic and spintronic properties within AuPt/ferromagnet (FM) bilayers (FM = CoFe, CoFeB, Py, and Co). A linear correlation between the volume and surface magnetic anisotropies is identified, potentially influenced by the magnetoelastic effect. The FM thickness dependence of the magnetic damping indicates that spin-memory loss due to the interfacial spin–orbit coupling (ISOC) and spin pumping to the heavy-metal layer contribute little to the damping. Instead, a notable contribution from two magnon scattering to the damping is recognized in AuPt/(Co, CoFe, CoFeB) bilayers, possibly originating from a magnetic inhomogeneity due to the ISOC. In addition, in contrast to the magnetic damping, spin–orbit-torque efficiencies are unlikely related to the ISOC in AuPt/FM systems. This work offers valuable insights into the correlations among magnetic and spintronic parameters arising from the interfaces, ultimately aiding in the advancement of magnetic memory and information processing systems. [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]

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We report a first-principles investigation based on density functional theory with the Hubbard U correction to identify the mechanism behind the electric-field modulation, via a - c domain-wall motion, of the anisotropic magnetoresistance (AMR) ratio in C o 2 FeSi / BaTi O 3 heterostructures. The effects of BaTi O 3 (BTO) electric polarization in the [ 001 ], [ 00 1 ¯ ], and [ 0 1 ¯ 0 ] directions on the FeSi / Ti O 2 and CoCo / Ti O 2 interface terminations are taken into account. We show that the response of the interface geometric and electronic properties to the BTO polarization depends on the interface termination. For instance, the pinning of atoms at the FeSi -terminated interface inhibits the [ 001 ] polarization. Through the a - c domain-wall motion, interface hybridized 3 d y z states shift in energy and change the minority-spin density of states at the Fermi level, modifying the AMR through the α = ρ ↓ ρ ↑ component. A discussion of the results based on the Campbell–Fert–Jaoul model with s - s and s - d scattering is provided. The electronic states of C o 2 FeSi inner layers remained mostly unchanged upon the transition between the ferroelectric domains, which indicates that long-range magnetoelastic effects have a negligible influence on the AMR ratio. Hence, the results indicate that interface bonding effects are the origin of the electric-field modulation of the AMR via a - c domain-wall motion in C o 2 FeSi / BaTi O 3 heterostructures. [ABSTRACT FROM AUTHOR]

A two dimensional boundary value problem of magnetoelasticity for a semi-infinite moving crack situated between an orthotropic half-space and an orthotropic layer has been considered. Also, it has been considered that the crack is agitated by an anti-plane shear wave. The contemplated problem has been reduced to a typical Wiener–Hopf equation by employing Fourier integral transform to the convenient boundary condition. The accomplished Wiener–Hopf equation has been solved only for asymptotic case to get the analytical expression of stress intensity factor (SIF) and crack tearing displacement (CTD). The dependence of several parameters including the magnetoelastic coupling factor, material constants, crack propagation velocity and crack depth from the upper surface on the SIF and CTD have been illustrated using variety of graphs. [ABSTRACT FROM AUTHOR]

The dependence of differential magnetic susceptibility χac(T) of metallic biaxially textured NiWx ribbons with a tungsten content of x = 5.5, 6.0, 7.4, 7.7 at % on planar mechanical tensile and compressive stresses has been studied in the temperature range of 50–350 K. To create the tensile and compressive stresses, the thermal cycling procedure is applied to the ribbons glued to the substrates made of Si and aluminum alloy D16T, respectively. It is shown that the main peculiarities of the magnetic susceptibility behavior can be explained by magnetic orientation transitions and the occurrence of internal stresses σ(T) that exceed the elastic limit of NiWx. [ABSTRACT FROM AUTHOR]

In this paper, we report for the first time on the theoretical and experimental investigation of Fe77.5Si7.5B15 amorphous glass-coated nanowires by analyzing samples with the same diameters in both cases. The hysteresis curves, the dependence of the switching field values on nanowire dimensions, and the effect of the magnetoelastic anisotropy on the magnetization processes were analyzed and interpreted to explain the magnetization reversal in highly magnetostrictive amorphous nanowires prepared in cylindrical shape by rapid quenching from the melt. All the measured samples were found to be magnetically bistable, being characterized by rectangular hysteresis loops. The most important feature of the study is the inclusion of the magnetoelastic anisotropy term that originates in the specific production process of these amorphous nanowires. The results show that the switching field decreases when the nanowire diameter increases and this effect is due to the reduction in anisotropy and in the intrinsic mechanical stresses. Moreover, the obtained results reveal the importance of factors such as geometry and magnetoelastic anisotropy for the experimental design of cylindrical amorphous nanowires for multiple applications in miniaturized devices, like micro and nanosensors. [ABSTRACT FROM AUTHOR]

Magnetic skyrmions have great potential for developing novel spintronic devices. The electrical manipulation of skyrmions has mainly relied on current-induced spin-orbit torques. Recently, it was suggested that the skyrmions could be more efficiently manipulated by surface acoustic waves (SAWs), an elastic wave that can couple with magnetic moment via the magnetoelastic effect. Here, by designing on-chip piezoelectric transducers that produce propagating SAW pulses, we experimentally demonstrate the directional motion of Néel-type skyrmions in Ta/CoFeB/MgO/Ta multilayers. We find that the shear horizontal wave effectively drives the motion of skyrmions, whereas the elastic wave with longitudinal and shear vertical displacements (Rayleigh wave) cannot produce the motion of skyrmions. A longitudinal motion along the SAW propagation direction and a transverse motion due to topological charge are simultaneously observed and further confirmed by our micromagnetic simulations. This work demonstrates that acoustic waves could be another promising approach for manipulating skyrmions, which could offer new opportunities for ultra-low power skyrmionics. Skyrmions, a type of topological spin texture, have garnered interest for use in spintronic devices. Typically, these devices necessitate moving the skyrmions via applied currents. Here, Yang et al demonstrate the driving of skyrmions by surface acoustic waves. [ABSTRACT FROM AUTHOR]

It is well established that many material properties, such as multiferroicity, magnetoresistance, or magnetoelectricity, emerge from strong interactions of spins and lattice (phonons). An in-depth understanding of spin-phonon coupling is key to understanding these properties. We demonstrate strong spin-phonon coupling in HoCrO3 using powder X-ray diffraction measurements. Our investigations confirm magnetoelastic effects below antiferromagnetic phase transition, TN • 142 K. The lattice parameters and unit cell volume decrease normally with temperature up to ~ TN, but decrease anomalously below TN. By fitting the background thermal expansion for a non-magnetic lattice using the Debye-Grüneisen equation, we determined the lattice strain ΔVM due to the magnetoelastic effects as a function of temperature. We have also established that the lattice strain due to the magnetoelastic effect in HoCrO3 couples with the square of the ordered magnetic moment of the Cr3+ ion. [ABSTRACT FROM AUTHOR]

It is well established that many material properties, such as multiferroicity, magnetoresistance, or magnetoelectricity, emerge from strong interactions of spins and lattice (phonons). An in-depth understanding of spin-phonon coupling is key to understanding these properties. We demonstrate strong spin-phonon coupling in HoCrO3 using powder X-ray diffraction measurements. Our investigations confirm magnetoelastic effects below antiferromagnetic phase transition, TN • 142 K. The lattice parameters and unit cell volume decrease normally with temperature up to ~ TN, but decrease anomalously below TN. By fitting the background thermal expansion for a non-magnetic lattice using the Debye-Grüneisen equation, we determined the lattice strain ΔVM due to the magnetoelastic effects as a function of temperature. We have also established that the lattice strain due to the magnetoelastic effect in HoCrO3 couples with the square of the ordered magnetic moment of the Cr3+ ion. [ABSTRACT FROM AUTHOR]

This paper presents a newly proposed domain wall energy-based model of the 2D strain dependence of relative magnetic permeability in highly grain-oriented anisotropic electrical steels. The model was verified utilizing grain-oriented M120-27s electrical steel sheet samples with magnetic characteristics measured by an automated experimental setup with a magnetic yoke. The model's parameters, identified in the differential evolution-based optimization process, enable a better understanding of the interaction between stress-induced anisotropy and magnetocrystalline anisotropy in electrical steels. Moreover, the consequences of the simplified description of grain-oriented magnetocrystalline anisotropy are clearly visible, which opens up the possibility for further research to improve this description. [ABSTRACT FROM AUTHOR]

We present a non-invasive method of detecting stress below the elastic limit in magnetic steel elements. The method, based on well-known magnetoelastic effects, relies on mechanical stress-induced permeability modulation. It does not measure absolute values and hence results in suitable in situ measurements in situations where small position or vibration changes can change absolute values. [ABSTRACT FROM AUTHOR]

The main objective of this study is to investigate the vibration behavior of soft magnetoelastic plates mounted close to the rectangular conductors conducting current that can be efficiently applicable in structures. New relationships are derived for electromagnetic interaction forces with magnetoelastic plates using the general form of Maxwell's equations and Lorentz forces. Based on von-Kámán strain-displacement relations and Hamilton's principle, nonlinear differential equations are further derived for the plate through classical first-order shear deformation theory. This research numerically investigates how different parameters affect the resonance features of these plates by discretizing the nonlinear equations based on Galerkin method. The obtained results demonstrate that the intensity of the magnetic field and electric current profoundly affects the vibration behavior of the plates. Through these effects, loss of energy will happen in the plate which in turn results in a decrease in the oscillation amplitude over time. [ABSTRACT FROM AUTHOR]

Various mechanical antennas have emerged to overcome the inherently narrower bandwidth and degraded efficiency in electrically small antennas. Among them, multiferroic antennas are expected to realize high-frequency applications and maintain their performance, even with significantly reduced sizes. However, experimental proof of such radiation from multiferroic or magnetoelectric coupling in the GHz range deserves further examination. This paper designs and fabricates a series of multiferroic antenna samples with mechanical resonances at around 3.5 and 6 GHz, and their radiation transmissions are tested at these resonances. Nickel, a magnetoelastic material, consistently exhibits magnetically induced radiation at both resonances. However, magnetic material consisting of Permalloy (Ni78Fe22), known for its much weaker magnetoelastic effects, still shows similar transmission behaviors at 3.67 GHz and enhanced power absorption at 6.42 GHz. Our results indicate that the dynamic response of magnetoelastic materials in the GHz band should differ from their response at the MHz and below bands. This evidence calls for further investigations of the source of magnetoelectric radiation. [ABSTRACT FROM AUTHOR]

The influence of the thermally induced magnetoelastic effect on the magnetization reversal field in 0.9 × 0.3 × 0.03-μm Ni particles formed on a single crystalline lithium triborate (LiB3O5) substrate has been studied. It has been shown experimentally that this substrate can reduce the magnetization reversal field of particles by a factor of more than 1.5 as the temperature of the sample increases from 30 to 45°C. This reduction of the reversal field is due to magnetoelastic anisotropy induced in the particles by the difference between the thermal expansion coefficients of the substrate along different crystallographic axes. [ABSTRACT FROM AUTHOR]

This study presents an intelligent soft robotic system capable of perceiving, describing, and sorting objects based on their physical properties. This work introduces a bimodal self‐powered flexible sensor (BSFS) based on the triboelectric nanogenerator and giant magnetoelastic effect. The BSFS features a simplified structure comprising a magnetoelastic conductive film and a packaged liquid metal coil. The BSFS can precisely detect and distinguish touchless and tactile models, with a response time of 10 ms. By seamlessly integrating the BSFSs into the soft fingers, this study realizes an anthropomorphic soft robotic hand with remarkable multimodal perception capabilities. The touchless signals provide valuable insights into object shape and material composition, while the tactile signals offer precise information regarding surface roughness. Utilizing a convolutional neural network (CNN), this study integrates all sensing information, resulting in an intelligent soft robotic system that accurately describes objects based on their physical properties, including materials, surface roughness, and shapes, with an accuracy rate of up to 97%. This study may lay a robotic foundation for the hardware of the general artificial intelligence with capacities to interpret and interact with the physical world, which also serves as an interface between artificial intelligence and soft robots. [ABSTRACT FROM AUTHOR]

Acoustoelectric transformation (occurrence of electromagnetic radiation under the action of an elastic wave) in a FeSe0.925S0.075 crystal in the presence of an external magnetic field has been studied. It is shown that the application of the magnetic field along the direction of propagation of the elastic wave leads to a rotation of the plane of polarization of the emitted electromagnetic wave. The physical mechanism is that the elastic deformation leads to the appearance of a non-diagonal component of the magnetic susceptibility and to the generation of an additional alternating magnetic moment perpendicular to the external magnetic field and to the elastic displacement. The observed features are interpreted as a manifestation of the Villari effect. A phenomenological description of the experimental results is presented. The observed effect shows that the symmetry of the low-temperature FeSe1–xSx phase belongs to the triclinic syngony. [ABSTRACT FROM AUTHOR]

Acoustoelectric transformation (occurrence of electromagnetic radiation under the action of an elastic wave) in a FeSe0.925S0.075 crystal in the presence of an external magnetic field has been studied. It is shown that the application of the magnetic field along the direction of propagation of the elastic wave leads to a rotation of the plane of polarization of the emitted electromagnetic wave. The physical mechanism is that the elastic deformation leads to the appearance of a non-diagonal component of the magnetic susceptibility and to the generation of an additional alternating magnetic moment perpendicular to the external magnetic field and to the elastic displacement. The observed features are interpreted as a manifestation of the Villari effect. A phenomenological description of the experimental results is presented. The observed effect shows that the symmetry of the low-temperature FeSe1–xSx phase belongs to the triclinic syngony. [ABSTRACT FROM AUTHOR]

Antiferromagnetic materials promise improved performance for spintronic applications as they are robust against external magnetic field perturbations and allow for faster magnetization dynamics compared to ferromagnets. The direct observation of the antiferromagnetic state, however, is challenging due to the absence of a macroscopic magnetization. Here, we show that the spin Hall magnetoresistance (SMR) is a versatile tool to probe the antiferromagnetic spin structure via simple electrical transport experiments by investigating the easy-plane antiferromagnetic insulators α − Fe 2 O 3 (hematite) and NiO in bilayer heterostructures with a Pt heavy-metal top electrode. While rotating an external magnetic field in three orthogonal planes, we record the longitudinal and the transverse resistivities of Pt and observe characteristic resistivity modulations consistent with the SMR effect. We analyze both their amplitude and phase and compare the data to the results from a prototypical collinear ferrimagnetic Y 3 Fe 5 O 12 /Pt bilayer. The observed magnetic field dependence is explained in a comprehensive model, based on two magnetic sublattices and taking into account magnetic field-induced modifications of the domain structure. Our results show that the SMR allows us to understand the spin configuration and to investigate magnetoelastic effects in antiferromagnetic multi-domain materials. Furthermore, in α − Fe 2 O 3 /Pt bilayers, we find an unexpectedly large SMR amplitude of 2.5 × 10 − 3 , twice as high as for prototype Y 3 Fe 5 O 12 /Pt bilayers, making the system particularly interesting for room-temperature antiferromagnetic spintronic applications. [ABSTRACT FROM AUTHOR]

The field-dependence elastic modulus of magnetostrictive films, also called Δ E or Δ G effect, is crucial for ultrasensitive magnetic field sensors based on surface acoustic waves (SAWs). In spite of a lot of demonstrations, rare attention was paid to the frequency-dependence of Δ E or Δ G effect. In this work, shear horizontal-type SAW delay lines coated with a thin FeCoSiB layer have been studied at various frequencies upon applying magnetic fields. The change of shear modulus of FeCoSiB has been extracted by measuring the field dependent phase shift of SAWs. It is found that the Δ G effect is significantly enhanced at high-order harmonic frequencies close to the ferromagnetic resonance frequency, increasing by ∼82% compared to that at the first SAW mode (128 MHz). In addition, the smaller the effective damping factor of a magnetostrictive layer, the more pronounced Δ G effect can be obtained, which is explained by our proposed dynamic magnetoelastic coupling model. [ABSTRACT FROM AUTHOR]

Ferromagnetic van der Waals (vdW) materials are of large current interest for the fundamental study of low‐dimensional magnetism and for potential applications in multilayer heterostructures. Cr2Ge2Te6 (CGT) is particularly exciting because it is a ferromagnetic semiconductor with tunable electronic and magnetic properties. Controlling the magnetic domain structure of CGT is a requirement for understanding its novel interface physics and for tuning behavior for potential devices. Herein, cryo‐Lorentz transmission electron microscopy is performed in the temperature range of 12–50K to directly image the magnetic domain structures in CGT. A rich phase diagram of domain structures including stripe domains, magnetic bubble lattices of mixed‐chirality, and topologically‐protected lattices of homochiral magnetic bubbles is observed. The types and chiralities of the bubbles can be controlled by topographical changes in the CGT flakes. Additionally, it is observed that in‐plane strain and magnetoelastic coupling can align and organize both bubble lattices and stripe domains. This study provides insights into creating and controlling complex magnetic domain structures for integration into multilayer heterostructures and for future studies of 2D magnetism. [ABSTRACT FROM AUTHOR]

Ferromagnetic van der Waals (vdW) materials are of large current interest for the fundamental study of low‐dimensional magnetism and for potential applications in multilayer heterostructures. Cr2Ge2Te6 (CGT) is particularly exciting because it is a ferromagnetic semiconductor with tunable electronic and magnetic properties. Controlling the magnetic domain structure of CGT is a requirement for understanding its novel interface physics and for tuning behavior for potential devices. Herein, cryo‐Lorentz transmission electron microscopy is performed in the temperature range of 12–50K to directly image the magnetic domain structures in CGT. A rich phase diagram of domain structures including stripe domains, magnetic bubble lattices of mixed‐chirality, and topologically‐protected lattices of homochiral magnetic bubbles is observed. The types and chiralities of the bubbles can be controlled by topographical changes in the CGT flakes. Additionally, it is observed that in‐plane strain and magnetoelastic coupling can align and organize both bubble lattices and stripe domains. This study provides insights into creating and controlling complex magnetic domain structures for integration into multilayer heterostructures and for future studies of 2D magnetism. [ABSTRACT FROM AUTHOR]

Prestressed rebars are usually used to apply vertical prestress to concrete to prevent web cracking. The reduction of working stress will affect the durability of the structure. However, the existing working stress detection methods for prestressed rebars still need to be improved. To monitor the working stress of rebars, a magnetic resonance sensor was introduced to carry out experimental research. The correlation between rebar stress and the sensor's induced voltage was theoretically analyzed using the magnetoelastic effect and magnetic resonance theory. A working stress monitoring method for prestressed rebars based on magnetic resonance was proposed. Working stress monitoring experiments were carried out for 16 mm, 18 mm, and 20 mm diameter rebars. The results showed that the induced voltage peak-to-peak value and the rebar prestress were nonlinearly correlated under different working conditions. Correlations between the characteristic indicators and the rebar working stress were obtained using nonlinear and linear fit. The cubic polynomial segmented fit outperformed the gradient overall linear fit, with the goodness of fit R2 greater than 0.96. The average relative error values of working stress monitoring were less than 5% under different working conditions. This provides a new method for working stress measurement of vertical prestressed rebars. [ABSTRACT FROM AUTHOR]

In recent years, antiferromagnetic materials have been attracting increasing interest for their stability in high magnetic fields and ultrafast magnetization dynamics. Since the energy scale of an interlayer exchange coupling (IEC) in a synthetic antiferromagnet (SAF) consisting of ferromagnetic/nonmagnetic/ferromagnetic multilayers is relatively smaller than that of an exchange coupling in antiferromagnetic materials, magnetic ordering of a SAF can be potentially controlled by an electric field, which is promising for energy-saving spintronic memory devices. However, an electric field-induced magnetoelastic response of SAFs on ferroelectric materials has not been sufficiently understood due to the presence of IEC that complicates magnetization dynamics. In this study, we prepare Co/Ru/Co SAFs with various amplitude of IEC on ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 substrates and systematically investigate their electric field-induced magnetoelastic response. We demonstrate that the magnetoelastic response disappears at the boundary where a switching between the antiferromagnetic and ferromagnetic IEC coupling occurs. The result provides insight into the coupling of the magnetoelastic effect and IEC and is useful in designing spintronic memory devices based on SAFs. [ABSTRACT FROM AUTHOR]

This work aims to propose an implicit algorithm for solving the magnetoelastic wave propagation in a magnetostrictive actuator. This algorithm is built by combining meshless methods with the Newmark implicit time scheme. The mathematical formulation of vibrations of the actuator is performed by modeling the experimental actuator device by a monodimensional magnetostrictive cylindrical rod attached to an elastic spring, subjected to an axial magnetic field. The formulation of the problem is carried out using the rod model. The study is carried out taking into account mechanical and magnetic effects described by a linear model of strain-stress magnetoelastic relations, whose coefficients depend on the square of the magnetic field, elastic, magnetostrictive, and magnetoelastic characteristics of the elastomagnetic material of which the rod is made. The dynamic equation which describes the magnetoelastic wave propagation in the actuator is obtained by applying the Lagrangian formalism based on the least action principle. The wave propagation is governed by a spatio-temporal partial differential equation whose coefficients are a function of on elastic, magnetostrictive, and magnetic characteristics and implicitly depends on time. The resolution of the dynamic equation is made by adopting two numerical approaches developed by combining the mesh-free collocation methods, the Moving Least Squares (MLS), and the Radial Point Interpolation Method (RPIM) with the Newmark implicit scheme temporal integration. By performing the spatial discretization of the displacement, we obtain a system of linear second-order ordinary differential equations (ODEs), then transform it into a system of first-order ordinary differential equations after integrating Newmark's implicit time scheme. A comparison of results computed by the proposed numerical approaches RPIM and MLS with experimental data available in the literature is presented. The stability and the solutions qualities of two meshless methods, RPIM and MLS, are also studied. The influence of magnetical and mechanical parameters as well as the coupling coefficients on the performance of the magnetostrictive actuator is also made. [ABSTRACT FROM AUTHOR]

Strain and temperature are important physiological parameters for health monitoring, providing access to the respiration state, movement of joints, and inflammation processes. The challenge for smart wearables is to unambiguously discriminate strain and temperature using a single sensor element assuring a high degree of sensor integration. Here, a dual‐mode sensor with two electrodes and tubular mechanically heterogeneous structure enabling simultaneous sensing of strain and temperature without cross‐talk is reported. The sensor structure consists of a thermocouple coiled around an elastic strain‐to‐magnetic induction conversion unit, revealing a giant magnetoelastic effect, and accommodating a magnetic amorphous wire. The thermocouple provides access to temperature and its coil structure allows to measure impedance changes caused by the applied strain. The dual‐mode sensor also exhibits interference‐free temperature sensing performance with high coefficient of 54.49 µV °C−1, low strain and temperature detection limits of 0.05% and 0.1 °C, respectively. The use of these sensors in smart textiles to monitor continuously breathing, body movement, body temperature, and ambient temperature is demonstrated. The developed multifunctional wearable sensor is needed for applications in early disease prevention, health monitoring, and interactive electronics as well as for smart prosthetics and intelligent soft robotics. [ABSTRACT FROM AUTHOR]

In this paper, the steel internal damping due to both the thermoelastic and the magnetoelastic phenomena has been investigated through a formulation based on thermodynamical potential joints with a hysteretic damping model. With the aim of focusing on the temperature transient in the solid, a first configuration has been considered, which is characterized by a steel rod with an imposed alternating pure shear strain in which only the thermoelastic contribution was studied. The magnetoelastic contribution was then introduced in a further configuration, in which a steel rod in free motion was subjected to torsion on its ends in the presence of a constant magnetic field. A quantitative assessment of the influence of the magnetoelastic dissipation in steel has been computed according to the Sablik-Jiles model by giving a comparison between the thermoelastic and the prevailing magnetoelastic damping coefficients. [ABSTRACT FROM AUTHOR]

Thin films of a lead-free magnetoelectric compound AlFeO3 have been deposited using a pulsed laser deposition technique. X-ray diffraction, X-ray absorption spectroscopy, and reflectivity measurements established the orthorhombic structure and a material density of 4.5 g/cm3, which is comparable to the bulk AlFeO3. The polycrystalline AlFeO3 film showed a strong magnetoelastic coupling. The Raman study carried out at variable temperatures and under an applied magnetic field at room temperature showed spectacular results. One of the Raman modes corresponding to AlFeO3 was found to vanish completely when the magnetic field of 0.08 T was applied at room temperature. The mode was also found to vanish between the temperature window of 280 K–236 K in temperature dependent studies. The observation was further supported by the detailed analysis of magnetization studies, which showed a change in the magnetic order in the same temperature interval. The invisibility of the Raman phonon mode has been attributed to the lattice deformation caused by the magnetoelastic effect. Additionally, the phonon frequencies showed renormalization below 200 K demonstrating a strong spin-lattice coupling. [ABSTRACT FROM AUTHOR]

Magnetoelastic effect in R2Ni2In (R = Tb, Tm), associated with the antiferro- to paramagnetic phase transition at the Néel temperature TN equal to 40 K (R = Tb) or 4.8 K (R = Tm), has been investigated by neutron powder diffraction. Rietveld refinement reveals that the orthorhombic crystal structure, reported at room temperature, is stable down to low temperatures, including magnetically ordered state. Based on the diffraction data, thermal evolution of the lattice parameters a, b and c and the unit cell volume V have been determined. Both the lattice parameters as well as the unit cell volume show distinct jumps in the vicinity of the respective Néel temperatures, indicating presence of the magnetoelastic effect. The values of the lattice strains Δa, Δb, Δc and change of the unit cell volume ΔV, associated with the antiferro- to paramagnetic phase transition, are reported. [ABSTRACT FROM AUTHOR]

The need for Alpha2-Macroglobulin (α2-M) detection has increased because it plays an important role in the diagnosis of diabetic nephropathy (DN). However, few sensors can realize the high-sensitive detection for α2-M with characteristics of being fast, flexible, wearable and portable. Herein, a biosensor based on a MnFe2O4@chitosan/MWCNTs/PDMS composite film was developed for α2-M detection. Due to the excellent magnetoelastic effect of MnFe2O4 nanoparticles, the stress signal of the biosensor surface induced by the specific antibody–antigen binding was transformed into the electrical and magnetic signal. Chitosan-coated MnFe2O4 particles were used to provide biological modification sites for the α2-M antibody, which simplified the conventional biological functionalization modification process. The MnFe2O4@chitosan particles were successfully prepared by a chemical coprecipitation method and the property was studied by TEM, FT-IR and XRD. MWCNTs were employed to enhance electrical conductivity and the sensitivity of the biosensor. The detection limit (LOD) was reduced to 0.1299 ng·mL−1 in the linear range from 10 ng∙mL−1 to 100 µg·mL−1, which was significantly lower than the limit of health diagnostics. The biosensor is fabricated by a simple method, with advantages of being rapid and highly-sensitive, and having selective detection of α2-M, which provides a novel method for the early diagnosis of DN, and it has potential in the point of care (PoC) field. [ABSTRACT FROM AUTHOR]

We have prepared Fe-Ni-system bilayer ribbons with different magnetostriction (compositions) and investigated the improvement of soft magnetic properties using the magnetoelastic effect. A toroidal core with D = 10 mm was made from the Fe6Ni94/Fe56Ni44 bilayer ribbon, and the B-H loop of the core was measured. The shape of the hysteresis loop dramatically changed depending on the inner layer (inner magnetic phase). This result indicates that the direction of the anisotropy induced by bending stress was changed depending on the inner layer. The slope of the B-H loop and coercivity reduced when the Fe56Ni44 layer was on the inner side. From the experimental results, we found that domain rotation was dominant for the magnetization process. Consequently, the increase in the coercivity over frequency could be suppressed by controlling the magnetization process. From these results, we found that a thin bilayer ribbon with positive and negative magnetostriction constant is an attractive material for reducing iron losses under high frequency. [ABSTRACT FROM AUTHOR]

This study showcases the interfacial magnetoelastic effect observed in flaky FeSiAl alloy powder absorbents, aimed at enhancing permeability in the decimeter-wave band for better absorption performance through Cr doping via wet ball-milling and subsequent annealing processes. The wet ball milling process facilitates the formation of a lamellar structure by inducing slip along shear stress in DO 3 and α-Fe nanocrystals. During annealing, the introduced Cr element partially impedes the transition from the α-Fe phase to the DO 3 phase, thereby amplifying the difference in magnetostrictive coefficients between these phases. Consequently, the flaky FeSiAlCr powders exhibit notably increased initial permeability and resonance frequency, particularly around 3 GHz, owing to domain rotation in the DO 3 phase. In comparison to previously reported counterparts, the composite derived from these powders demonstrates a significant enhancement in the real part of effective permeability by approximately 66 %, alongside a 17 % reduction in density. Consequently, this composite exhibits a lowered reflection loss of below −5 dB within the frequency range of 0.7–3 GHz, reaching a minimum of −11 dB at 1.57 GHz, specifically with a thickness of 1.6 mm. These findings present an effective strategy for enhancing the magnetic permeability of alloy powders. The resultant microwave absorbing materials hold promising applications in stealth technology and wireless communication electronics. • Flaky FeSiAlCr alloy powder absorbents exhibit an interfacial magnetoelastic effect. • The effect generated a dual dispersion in permeability, in line with a stress model. • The 1.6 mm-thick-composite has a RL below −5 dB in 0.7–3 GHz with a minimum of −11 dB. [ABSTRACT FROM AUTHOR]

[Display omitted] • The flexible ME biosensor based on Tf-AuNCs was developed for 5-HT detection. • In order to improve the sensitivity, the "sandwich" structure was proposed. • By using clinical serum, the reliability and feasibility of biosensor has been verified. • The ME biosensor can realize multi-pattern signal recognition. • The biosensor can sensitively and specifically detect 5-HT with LOD of 0.33 ng/ml. 5-hydroxytryptamine (5-HT), a mono-amine neurotransmitter, plays an important role in regulating the dynamics of neural circuits in the central nervous system and enteric nervous system. Accurate and sensitive monitoring of 5-HT will provide critical information for diagnosing many psychiatric and neurological disorders. However, there are no superior clinical assays for the detection of 5-HT, and existing methods of gas chromatographs and mass spectrometers are expensive, limiting portable and real-time monitoring as diagnostic approaches in the clinical setting. Therefore, a convenient, rapid, and low-cost method for the detection of 5-HT is still in demand in current clinical medicine. Herein, a novel flexible magnetoelastic (ME) biosensor with "sandwich" structure is proposed for 5-HT detection based on transferrin encapsulated gold nanoclusters (Tf-AuNCs). Combined with the magnetoelastic effect of CoFe 2 O 4 , the excellent conductivity of silver nanowires (AgNWs), and the fluorescence properties of Tf-AuNCs, the ME biosensor designed in this paper can achieve multi-signal recognition. Rapid and sensitive detection of 5-HT is achieved by a biosensing process that converts surface stress signal into magnetoelectric signals. The biosensor is capable of detecting 5-HT with different concentrations in a linear range of 10 ng/mL-100 μg/mL (R2 = 0.97119) with a lower detection limit (LOD) of 0.33 ng/mL. The accurate measurement results of 5-HT in human serum of clinical samples demonstrated the feasibility of the biosensor for 5-HT detection. This flexible ME biosensor was prepared in a simple process with great specificity and stability, providing a portable analytical device for the rapid and sensitive detection of 5-HT, which is of great significance for the clinical research of various neurological diseases. [ABSTRACT FROM AUTHOR]

The magnetic, magnetocaloric, thermal expansion, magnetostriction, and heat capacity measurements of Gd5−xTixSi2Ge2 (x = 0, 0.05, 0.1) compounds have been carried out in a wide range of fields and temperatures. The Ti addition was found to increase the temperature of magnetic ordering and change the order of phase transition with preservation of high magnetocaloric effect values. At the same time, the large temperature and field hysteresis, observed for ΔT-effect in Gd5Si2Ge2, significantly decrease when Ti is added. The obtained results can be explained by the decoupling of magnetic and structural phase transition with Ti substitution. It is also shown that the magnetoelastic energy has a the strong influence on the type of phase transition for investigated compounds. [ABSTRACT FROM AUTHOR]

The magnetic, magnetocaloric, thermal expansion, magnetostriction, and heat capacity measurements of Gd5−xTixSi2Ge2 (x = 0, 0.05, 0.1) compounds have been carried out in a wide range of fields and temperatures. The Ti addition was found to increase the temperature of magnetic ordering and change the order of phase transition with preservation of high magnetocaloric effect values. At the same time, the large temperature and field hysteresis, observed for ΔT-effect in Gd5Si2Ge2, significantly decrease when Ti is added. The obtained results can be explained by the decoupling of magnetic and structural phase transition with Ti substitution. It is also shown that the magnetoelastic energy has a the strong influence on the type of phase transition for investigated compounds. [ABSTRACT FROM AUTHOR]

We consider some direct and inverse problems associated with the vibration of an elastic conductive body governed by the Lamé and Maxwell equations coupled through the nonlinear magnetoelastic effect. First, we prove the existence and uniqueness result for a mixed initial-boundary value problem. Uniqueness is proved under additional assumptions on the smoothness of the solution. Second, we prove the solvability of an inverse problem, which consists of identifying the unknown scalar function α (t) in the elastic force α (t) β (x , t) acting on the body when some additional measurement is available. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effects of temperature and magnetoelastic load, on the free vibration of an elastomer sandwich beam with magnetorheological (MR) core and functionally graded material (FGM) constraining lamina under high temperature environment. This sandwich beam is named FGMR beam in this paper. The material properties of the functionally graded material layers are assumed to be temperature-dependent and vary continuously through-the-thickness according to a simple power-law distribution in terms of the volume fractions of the constituents. Also, it is assumed that the beam may be clamped, hinged, or free at its ends and is subjected to one-dimensional steady-state heat conduction in the thickness direction. The classical Hamilton's principle and the assumed mode method are used to set up the equations of motion. The convergence of the method is examined and the accuracy of the results is verified by comparing the results with those available. In fact, the aim of this study is to investigate the effect of some parameters on the dynamic behavior of a sandwich beam with magnetorheological core and FGM constraining layers under temperature environment. First, the effects of magnetic field intensity on natural frequency and modal loss factor of the FGMR beam are studied. Subsequently the influence of temperature distribution on the vibration of FGMR sandwich beam is shown for different boundary condition and volume fraction index. Finally, the effect of the slenderness ratio on the fundamental frequency is presented. The results show that the modal characteristics are significantly influenced by the applied magnetic field, volume fraction index, temperature change, slenderness ratio, and the end support conditions. [ABSTRACT FROM AUTHOR]

Skin-integrated electronics that directly interact with machines are transforming our ways of life toward the emerging trend of the metaverse. Consequently, developing a wearable and skin-conformal interface that simultaneously features waterproofness, low cost, and low power consumption for human–machine interaction remains highly desired. Herein, a stretchable, inexpensive, and waterproof magnetoelastic sensor array has been developed as a secondary skin for self-powered human–machine interaction. The magnetoelastic sensor array utilizes the giant magnetoelastic effect in a soft system, which converts mechanical pressure to magnetic field variation and, when coupled with the magnetic induction, can generate electricity. In such a way, our magnetoelastic sensor array comprises the giant magnetomechanical coupling layer made up of nanomagnets and a porous silicone rubber matrix, and the magnetic induction layer, which are coils patterned by liquid metal. With programmable functionalities, the soft magnetoelastic sensor array can supply different commands by producing bespoke electric signals from human finger touch with an optimal signal-to-noise ratio of 34 dB and a rapid response time of 0.2s. To pursue a practical application, the soft magnetoelastic sensor array can wirelessly turn on and off a household lamp and control a music speaker via Bluetooth continuously in real time, even with contact with high-humidity environments such as heavy perspiration. With a collection of compelling features, the soft magnetoelastic sensor array puts forth a unique and savvy avenue of self-powered bioelectronic technology that practically enables a wider variety of applications for wearable human–machine interaction. [ABSTRACT FROM AUTHOR]

Magnetic skyrmions are vortex‐like spin textures, which can be manipulated by external stress or pressure via magnetoelastic effects. Herein, the observation of isostructural phase transition in a biskyrmion host hexagonal MnNiGa at pressure P ≈4 GPa using pressure‐dependent synchrotron X‐Ray powder diffraction (XRD) data analysis is presented. The XRD data reveals anisotropic compression behavior with pressure with different compression rates of the a‐axis in the basal plane and the c‐axis in the prismatic plane. However, the hexagonal symmetry remains unchanged for pressure up to 14 GPa. Fitting of unit cell volume with pressure using a second‐order Birch–Murnaghan equation of state reveals that the data fall into two distinct curves for those above and below 4 GPa. Herein, the understanding of crystal structure with the application of hydrostatic pressure in the biskyrmion host MnNiGa is contributed to, wherein the skyrmion textures can be manipulated by pressure due to their magnetoelastic character. [ABSTRACT FROM AUTHOR]

Electrical switching of antiferromagnets is an exciting recent development in spintronics, which promises active antiferromagnetic devices with high speed and low energy cost. In this emerging field, there is an active debate about the mechanisms of current-driven switching of antiferromagnets. For heavy-metal/ferromagnet systems, harmonic characterization is a powerful tool to quantify current-induced spin-orbit torques and spin Seebeck effect and elucidate current-induced switching. However, harmonic measurement of spin-orbit torques has never been verified in antiferromagnetic heterostructures. Here, we report harmonic measurements in Pt/α-Fe2O3 bilayers, which are explained by our modeling of higher-order harmonic voltages. As compared with ferromagnetic heterostructures where all current-induced effects appear in the second harmonic signals, the damping-like torque and thermally-induced magnetoelastic effect contributions in Pt/α-Fe2O3 emerge in the third harmonic voltage. Our results provide a new path to probe the current-induced magnetization dynamics in antiferromagnets, promoting the application of antiferromagnetic spintronic devices. Harmonic measurements have been used extensively in ferromagnetic/heavy metal heterostructures to characterize the magnetization dynamic; however, it has remained unclear about whether such techniques could be applied to antiferromagnetic devices. Here, Cheng et al demonstrate such a harmonic measurement approach in an antiferromagnet. [ABSTRACT FROM AUTHOR]

The magnetoelastic properties and behaviors arising from the flux-pinning effect are investigated for a long rectangular superconducting strip subject to a combination of applied transport current and magnetic field. Based on the Bean critical state model and linear elastic theory, the flux-pinning-induced stress in the superconducting strip is analytically obtained under the zero-field cooling condition. In particular, the magnetostriction performance for the strip with a one-sided restraint condition is then investigated. The results show that the trapped magnetic flux is distributed asymmetrically along the y-direction. A non-zero resultant force is consequently observed from the magnetization arising from the applied transport current and magnetic field. An obvious tension stress emerges around the constrained side of the strip along which the highest probability for cracking occurs and leads to a structural instability. The analytical results give insight into the flux-pinning-induced stress and magnetostriction response of the superconducting strip under both complex carrying-current and applied magnetic field conditions. These results may also provide helpful guidance in avoiding the breakdown of high-temperature superconductors. [ABSTRACT FROM AUTHOR]

Magnetic microswimmers, composed of hard and soft ferromagnets connected by an elastic spring, are modelled under low Reynolds number conditions in the presence of geometrical boundaries. Approaching a surface, the magneto-elastic swimmer's velocity increases and its trajectory bends parallel to the surface contour. Further confinement to form a planar channel generates new propagation modes as the channel width narrows, altering the magneto-elastic swimmer's speed, orientation, and direction of travel. Our results demonstrate that constricted geometric environments, such as occuring in microfluidic channels or blood vessels, may influence the functionality of magnetoelastic microswimmers for applications such as drug delivery. [ABSTRACT FROM AUTHOR]

Surface acoustic waves (SAWs) are elastic waves propagating on the surface of solids with the amplitude decaying into the solid. The well-established fabrication of compact SAW devices, together with well-defined resonance frequencies, places SAWs as an attractive route to manipulate the magnetization states in spintronics, all of which is made possible by the magnetostriction and magnetoelastic effects. Here, we review the basic characteristics of SAW devices and their interaction out-of-resonance and in-resonance with the magnetization in thin films. We describe our own recent results in this research field and closely related works and provide our perspectives moving forward. [ABSTRACT FROM AUTHOR]

Here, we report on a composite nanomechanical resonant magnetometer with magnetoelastic thin film integrated on the surface of a film bulk acoustic resonator (FBAR). By exploiting the delta-E effect of magnetoelastic thin film and resonance characteristic in piezoelectric thin film, we theoretically and experimentally demonstrate the capability to realize ultrahigh resonance frequency and excellent magnetic field sensitivity in such composite configuration, thereby greatly improving the limit of detection of weak magnetic field. The proposed FBAR-based resonant magnetometer achieves maximum magnetic sensitivity of 137 kHz/Oe in a proof-of-concept device without structural optimization, corresponding to a noise equivalent power as low as 7 nT/Hz1/2. Further study indicates that by optimizing the thicknesses of the magnetic sensitive layer and piezoelectric layer, an unprecedented sensitivity of 5 GHz/Oe with an exceptional limit of detection of weak magnetic field down to 190 ${f}\text{T}$ /Hz1/2 could be potentially achieved. Our work provides a forward new and exciting route toward ultralow magnetic field detection in civilian and military applications. [ABSTRACT FROM AUTHOR]

Efficient manipulation of antiferromagnetic (AF) domains and domain walls has opened up new avenues of research towards ultrafast, high-density spintronic devices. AF domain structures are known to be sensitive to magnetoelastic effects, but the microscopic interplay of crystalline defects, strain and magnetic ordering remains largely unknown. Here, we reveal, using photoemission electron microscopy combined with scanning X-ray diffraction imaging and micromagnetic simulations, that the AF domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects. We demonstrate that microtwin defects, which develop across the entire thickness of the film and terminate on the surface as characteristic lines, determine the location and orientation of 180∘ and 90∘ domain walls. The results emphasize the crucial role of nanoscale crystalline defects in determining the AF domains and domain walls, and provide a route to optimizing device performance. Antiferromagnets offer the potential for higher speed and density than ferromagnetic materials for spintronic devices. Here, Reimers et al study the domain structure of CuMnAs, demonstrating the role of defects in stabilizing the location and orientation of antiferromagnetic domain walls. [ABSTRACT FROM AUTHOR]

Magnetoelastic materials permit the development of remote-query strain sensors for use in situations of difficult access. In this work, we examined materials for a remote-query strain sensor based on the ΔE effect. An applied stress modifies the magnetic field produced by a transducer glued to the sample and thereby changes the resonant frequency of a vibrating amorphous ribbon. We considered several amorphous alloys for both the vibrating ribbon and the transducer. To eliminate the casting stress and improve the anisotropy, ribbons were annealed in a transverse magnetic field. This resulted in a dramatic improvement in the sensor performance when sensors were biased above the anisotropy field. For example, a Metglas 2826MB3 ribbon with resonant frequency of 62 kHz showed frequency shifts of up to 5 kHz for a deformation of 0.03%. These results are in good agreement with models for the ΔE effect. [ABSTRACT FROM AUTHOR]

In this paper, a fully coupled analytical model between elastodynamics with micromagnetics is used to study the switching energies using voltage induced mechanical bending of a magnetoelastic bit. The bit consists of a single domain magnetoelastic nano-ellipse deposited on a thin film piezoelectric thin film (500 nm) attached to a thick substrate (0.5 mm) with patterned electrodes underneath the nano-dot. A voltage applied to the electrodes produces out of plane deformation with bending moments induced in the magnetoelastic bit modifying the magnetic anisotropy. To minimize the energy, two design stages are used. In the first stage, the geometry and bias field (Hb) of the bit are optimized to minimize the strain energy required to rotate between two stable states. In the second stage, the bit's geometry is fixed, and the electrode position and control mechanism is optimized. The electrical energy input is about 200 (aJ) which is approximately two orders of magnitude lower than spin transfer torque approaches. [ABSTRACT FROM AUTHOR]