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Flexible electronic devices extended abilities of humans to perceive their environment conveniently and comfortably. Among them, flexible magnetic field sensors are crucial to detect changes in the external magnetic field. State‐of‐the‐art flexible magnetoelectronics do not exhibit low detection limit and large working range simultaneously, which limits their application potential. Herein, a flexible magnetic field sensor possessing a low detection limit of 22 nT and wide sensing range from 22 nT up to 400 mT is reported. With the detection range of seven orders of magnitude in magnetic field sensor constitutes at least one order of magnitude improvement over current flexible magnetic field sensor technologies. The sensor is designed as a cantilever beam structure accommodating a flexible permanent magnetic composite and an amorphous magnetic wire enabling sensitivity to low magnetic fields. To detect high fields, the anisotropy of the giant magnetoimpedance effect of amorphous magnetic wires to the magnetic field direction is explored. Benefiting from mechanical flexibility of sensor and its broad detection range, its application potential for smart wearables targeting geomagnetic navigation, touchless interactivity, rehabilitation appliances, and safety interfaces providing warnings of exposure to high magnetic fields are explored. [ABSTRACT FROM AUTHOR]

Layered perovskite-like oxides with the Aurivillius phase's structure are promising for high-technology industries such as magnetoelectronics, photonics, and catalysis. This work reports the synthesis condition and magnetic properties of the Sr-doped ceramic materials (BSFTO) based on four-layer Aurivillius phase Bi5FeTi3O15. (Bi1−xSrx)5FeTi3O15−δ (x = 0–0.14) ceramics were synthesized by a solid-state reaction method, and their structure (XRD), morphology (SEM, helium pycnometry), elemental composition (EDX), and sintering (dilatometry) were investigated. The XRD/EDX measurements show that the single-phase materials based on BSFTO solid solutions were synthesized with x = 0.0–0.1, which corresponds to the content of strontium 0–50 mol.%. The optimal synthesis regimes of the obtained materials and their sintering temperatures were determined. At x < 0.1, field dependent magnetization indicates a possible low-temperature magnetic ordering, and they have nonzero magnetization at RT. The results of the present work confirm the possibility of successful synthesis of pure-phase BSFTO materials that can have promising functional applications. [ABSTRACT FROM AUTHOR]

Materials with a layered perovskite-like structure of the Aurivillius phase type are important for technology fields such as magnetoelectronics and photocatalysis. Features of phase formation during the synthesis of nano- and macrocrystalline materials based on Bi6Fe2Ti3O18 with the five-layer Aurivillius phase structure are described. Samples were characterized by powder XRD, DSC/TG, dilatometry, and SEM/EDX. The temperatures of the beginning of formation, the Curie point, the beginning of decomposition and activation of sintering of the obtained materials, and the value of the coefficient of linear thermal expansion were determined. The technological possibility of controlling the dispersion of the obtained materials by changing the synthesis conditions is shown. [ABSTRACT FROM AUTHOR]

Based on magneto‐electric (ME) effect and spin Hall effect (SHE), the authors propose a novel spin logic device named MESH‐SLD. In MESH‐SLD, the charge current is transmitted in the channel by employing inverse SHE, which solves the dissipation problem of spin current in the channel of all‐spin logic device (ASLD). By using a magnetization‐dynamics/spin‐transport hybrid model, the authors have investigated the influence of working voltage, channel lengths, and materials on the performance of the MESH‐SLD. And the simulation results show that the energy dissipation of the MESH‐SLD only increases approximately linearly with the increase of channel length, while the switching delay remains almost unchanged. In addition, with the increase of the spin Hall angle of the channel material, the energy dissipation and the minimum working voltage of the MESH‐SLD decrease significantly. Most importantly, compared with conventional ASLD, the proposed MESH‐SLD improve the switching delay and the energy dissipation by about 2.5 times and 851.8 times, respectively. [ABSTRACT FROM AUTHOR]

With the merits of high sensitivity, high stability, high flexibility, low cost, and simple manufacturing, flexible magnetic field sensors have potential applications in various fields such as geomagnetosensitive E-Skins, magnetoelectric compass, and non-contact interactive platforms. Based on the principles of various magnetic field sensors, this paper introduces the research progress of flexible magnetic field sensors, including the preparation, performance, related applications, etc. In addition, the prospects of flexible magnetic field sensors and their challenges are presented. [ABSTRACT FROM AUTHOR]

Abstract Based on magneto‐electric (ME) effect and spin Hall effect (SHE), the authors propose a novel spin logic device named MESH‐SLD. In MESH‐SLD, the charge current is transmitted in the channel by employing inverse SHE, which solves the dissipation problem of spin current in the channel of all‐spin logic device (ASLD). By using a magnetization‐dynamics/spin‐transport hybrid model, the authors have investigated the influence of working voltage, channel lengths, and materials on the performance of the MESH‐SLD. And the simulation results show that the energy dissipation of the MESH‐SLD only increases approximately linearly with the increase of channel length, while the switching delay remains almost unchanged. In addition, with the increase of the spin Hall angle of the channel material, the energy dissipation and the minimum working voltage of the MESH‐SLD decrease significantly. Most importantly, compared with conventional ASLD, the proposed MESH‐SLD improve the switching delay and the energy dissipation by about 2.5 times and 851.8 times, respectively.

Since the resurgence of multiferroics research, significant advancement has been made in the theoretical and experimental investigation of the electric field control of magnetization, magnetic anisotropy, magnetic phase, magnetic domains, and Curie temperature in multiferroic heterostructures. As a result of these advances, multiferroic heterostructures are on a trajectory to impact spintronics applications through the significantly reduced energy consumption per unit area for magnetization switching (1–500 μJ cm−2) when compared to that of current-driven magnetization switching (0.2–10 mJ cm−2). Considering this potential impact, it becomes necessary to understand magnetoelectric switching dynamics and characteristic switching times. The body of experimental work investigating magnetoelectric switching dynamics is rather limited, with the majority of room temperature converse magnetoelectric switching measurements reported having employed relatively long voltage pulses. Recently, however, the field has started to consider the kinetics of the switching path in multiferroic (and ferroelectric) switching. Excitingly, the results are challenging our understanding of switching processes while offering new opportunities to engineer the magnetoelectric effect. Considering the prospects of multiferroics for beyond-CMOS applications and the possible influence on operational speed, much remains to be understood regarding magnetoelectric switching kinetics and dynamics, particularly at reduced dimensions and under the influence of boundary effects resulting from strain, electrostatics, and orientation. In this article, we review magnetoelectric switching in multiferroic heterostructures for the electric field control of magnetism. We then offer perspectives moving toward the goal of low energy-delay spintronics for computational applications. [ABSTRACT FROM AUTHOR]

Till now application of printed magnetoelectronics is hindered by lack of large area exchange coupled metallic multilayers required to produce printable magneto‐sensory inks. Large‐scale roll‐to‐roll (R2R) fabrication process is an attractive approach owing to its capabilities for high volume, high throughput, and large area manufacturing. Precise and high performance R2R sputtering technology is developed to fabricate large area giant magnetoresistive (GMR) thin‐films stacks that contain 30 metallic bilayers prepared by continuous R2R sputtering of Co and Cu sequential on a hundred meters long polyethylene terephthalate (PET) web. The R2R sputtered Co/Cu multilayer on a 0.2 × 100 m2 PET web exhibits a GMR ratio of ≈40% achieving the largest area exchange coupled room temperature magneto‐sensitive system demonstrated to date. The prepared GMR thin‐film is converted to magnetosensitive ink that enables printing of magnetic sensors with high performance in a cost‐efficient way, which promotes integration with printed electronics. An average GMR ratio of ≈18% is obtained for 370 printed magnetic sensors. The realized precise R2R sputtering approach can also be extended to a wide range of hybrid thin‐film material systems opening up a path for new functional inks applied with printing technologies. [ABSTRACT FROM AUTHOR]

Active magnetic motion sensing relies on a combination of magnetic sensors and actuators to indirectly sense a time-varying change in position and orientation. Based on our previous work on a 1D setup with magnetoelectric (ME) sensors, we introduce a concept for a full 6D sensing system, which is positioned as a modular setup for human movement pattern capture with regard to neurodegenerative diseases. In this paper, we implemented an inverse model based on ideal triaxial sensors and coils. We then included results from the previous experiments to estimate the prospective performance in a physical setup. We obtained a spatial error of a few cm and approx. 10° with focus on superimposed sinusoidal movements of 1, 5, and 10 Hz. [ABSTRACT FROM AUTHOR]

We report the magnetic field dependence of the threshold electric field Eth for the magnetoelectric switching of the perpendicular exchange bias in Pt/Co/Au/Cr2O3/Pt stacked films using a reversible isothermal electric tuning approach. The Eth values for the positive-to-negative and negative-topositive switching are different because of the unidirectional nature of the interfacial exchange coupling. The Eth values are inversely proportional to the magnetic-field strength, and the quantitative analysis of this relationship suggests that the switching is driven by the nucleation and growth of the antiferromagnetic domain. We also find that the magnetic-field dependence of Eth exhibits an offset electric field that might be related to the uncompensated antiferromagnetic moments located mainly at the interface. [ABSTRACT FROM AUTHOR]

With the merits of high sensitivity, high stability, high flexibility, low cost, and simple manufacturing, flexible magnetic field sensors have potential applications in various fields such as geomagnetosensitive E-Skins, magnetoelectric compass, and non-contact interactive platforms. Based on the principles of various magnetic field sensors, this paper introduces the research progress of flexible magnetic field sensors, including the preparation, performance, related applications, etc. In addition, the prospects of flexible magnetic field sensors and their challenges are presented.

Crack difficulties are important research topics for multiferroic composite media, which offer a lot of potential for producing multifunctional devices. It is put into consideration the magneto-electro-thermo-elastic coupling effect. The two crack surfaces are symmetrically loaded by a combination of homogeneous thermal, magnetic, electric, and mechanical loadings. Only the shallower region of a deep flaw in the wall structure inside the skin-depth layer impacts the initial temperature Induction Thermography (IT) response while assessing ferromagnetic constructions, but the deeper part has zero influence. This paper provides an exhaustive overview of these crack behavior studies as well as proposes a course of action for future exploration. Based on the literature, three types of crack behavior, which are magnetoelastic, ferromagnetic, and piezoelectric (PE), were explored significantly. Literature reviews have indicated that the magnetoelastic crack studied is popular among researchers around the world. Besides, the procedure and conditions are easier and faster compared to ferromagnetic and PE. Future research should therefore concentrate on the investigation effects of the magnetoelastic crack. [ABSTRACT FROM AUTHOR]

The dynamic response of an anisotropic multilayer magneto-electro-elastic (MEE) plate due to an external excitation is investigated in this work, using the stiffness matrix approach. A parametric study is performed by varying the stacking sequence, polarization direction, boundary conditions, and interlayer thickness. The proposed method yields the numerical estimation of the dispersion curve and the free vibration of the Lamb waves for different crystallographic orientations and magneto-electric boundary conditions. It is demonstrated that the anisotropy highly affects the dispersion curve and the non-dimensional frequency, and also decreases the interlayer thickness of the magneto-electro-elastic multilayer and raises the phase velocity of the fundamental symmetric Lamb mode vibration. The key outcomes of this research can serve as a reference in the design and analysis of new smart magneto-electro-elastic structures. [ABSTRACT FROM AUTHOR]

Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

The spin-transfer torque magnetic tunneling junction (MTJ) technology may pave a way to a universal memory paradigm. MTJ devices with perpendicular magnetic anisotropy have the potential to have high thermal stability, high tunneling magnetoresistance, and low critical current for energy-efficient current-induced magnetization switching. Using devices fabricated through focused ion beam etching with Ga-and Ne-ion beams, this paper aimed to understand the size dependence of the current/voltage characteristics in the sub-10 nm range. The switching current density drastically dropped around 1 MA/cm2 as the device size was reduced below 10 nm. A stability of over 22 kT measured for a 5 nm device indicated a significantly reduced spin relaxation time.

We have examined a dynamical spin injection in a CoFeB/Pt/CoFeB trilayered structure. Although the contribution of the spin pumping was eliminated by the symmetric spin injection from the upper and lower CoFeB layers, a clear voltage change due to the inverse spin Hall effect has been observed. We find that the observed signal can be quantitatively explained by considering the thermal spin injection due to the heating effect during ferromagnetic resonance (FMR). This innovative demonstration indicates the significant contribution of FMR heating in the dynamical spin injection. [ABSTRACT FROM AUTHOR]

The micromagnetic domain structure of MnAs films gave place to an intense research activity in the last few years due to its potential application in magneto-electronic devices such as domain-wall track memories and logic circuits. These applications require a full knowledge of miniaturization effects on the magnetic properties of the material. In this work, X-ray photoemission electron microscopy has been used for imaging magnetic domains in lithographically fabricated MnAs ribbons, addressing the dependence of the domain configuration on film thickness and ribbon width. Our experiments show a transition from head-on to regular stripe domains below a critical width/thickness ratio wc ≈ 6. Micromagnetic simulations suggest that this transition is correlated to the magnetic structure of the surface plane. Depending on the ribbon width and thickness, the magnetic configuration is shown to evolve from flux-closure domain structure to a state of almost homogeneous magnetization, observed for narrower ribbons. The evolution of the domain structure, magnetic fraction, and magnetization with temperature has been studied across the ferromagnetic/paramagnetic transition. Our experiments show that the magnetic configuration in ribbons exhibits higher stability to temperature variations than in as-cast films. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME) coupling by acoustic waveguide was developed. A very strong axial ME response was observed. The dependences of the sample size and the frequency of the ac field on the ME coupling were investigated. Several resonant points were observed in the frequency range applied (<50 kHz). Analysis shows that the standing waves transmitted in the waveguide were responsible for those resonances. And the resonant frequencies were closely influenced by the geometrical size of the waveguide. A resonant condition related to the size of the sample was obtained. The axial (or longitudinal) and transversal ME coefficients were observed to be up to 62 and 6 (V cm-1 Oe-1) at resonant points, respectively, indicating that the axial ME effect in this device was much higher than its transversal ones. A series of double-peak curves of axial ME coefficient versus magnetic field were observed. The significance of the double-peak curves was discussed. [ABSTRACT FROM AUTHOR]

A size effect of magnetic FeCo clusters in Na0.5Bi0.5TiO3/FeCo composites is presented, which is embodied by a strong size‐dependent magnetostrictive effect and magnetoelectric (ME) coupling effect. The size evolution of magnetic clusters induces the change of elastic energy in the magnetic phase, which is the key reason for the tunable magnetostrictive and mangetoelectric effects. An interface stress transferring mode is used to describe the coupling effect of the composites. This work explores a route to modulate ME materials by amorphous alloy clusters, which is of great significance to the development of magnetoelectronics. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication and characterization of a new type of magnetoelectric polymer nanocomposite that exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of high aspect ratio ferromagnetic iron nanowires embedded inside a ferroelectric co-polymer poly(vinylindene fluoride-trifluoroethylene), P(VDF-TrFE). The nanocomposite has been fabricated via a simple low temperature spin coating technique. Structural, ferromagnetic, ferroelectric, and magnetoelectric properties of the developed nanocomposite have been characterized. The nanocomposite films showed isotropic magnetic properties due to the random orientation of the iron nanowires inside the film. In addition, the embedded nanowires did not hinder the ferroelectric phase development of the nanocomposite. The developed nanocomposite showed a high magnetoelectric coupling response of 156 mV/cmOe measured at 3.1 kOe DC bias field. This value is among the highest reported magnetoelectric coupling in two phase particulate polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Electronic skins (e‐skins) have established themselves as a versatile technology to restore or enhance human perception, and potentially enable softer robotics. So far, the focus has been mostly on reproducing the traditional functions associated with human skin, such as, temperature, pressure, and chemical detection. New developments have also introduced nonstandard sensing capabilities like magnetic field detection, to spawn the field of magnetosensitive e‐skins. Adding a supplementary information channel—an electronic sixth sense—allows humans to utilize the surrounding magnetic fields as stimuli for touchless interactions. Due to their vectorial nature, these stimuli can be used to track motion and orientation in 3D, opening the door to various kinds of gestural control for interactive devices. This approach to tracking provides an alternative or complement to optic‐based systems, which usually rely on cameras or infrared emitters, that cannot easily capture fine motion when objects are far from the source or the line‐of‐sight is obtruded. Here, the background, fabrication techniques, and recent advances of this field are reviewed; covering important aspects like: directional perception, geomagnetic field detection, on‐site conditioning, and multimodal approaches. The aim is to give the reader a general perspective and highlight some new avenues of research, toward artificial magnetoception. [ABSTRACT FROM AUTHOR]

The realization of mechanically compliant spintronic elements relies on magnetic thin films prepared on flexible polymeric foils. Due to the strong difference in the mechanical properties of the magnetic thin film and the polymeric support, strong effects of heterogeneous strain emerge, which govern the magnetic response of the magnetic nanomembrane. Herein, the effect of the heterogeneous strain in a prototypical magnetic nanomembrane of Ni on the application‐relevant polyimide foil is studied. The distribution of the magnetoelastic field in the case of the heterogeneous strain is taken into account and compared with the case of the free‐standing Ni thin film. It is shown that the reversal process is strongly influenced by the heterogeneity at the early stages. Indeed, the reversal is characterized by two modes in the heterogeneous case, due to the strain localization in the nanomembrane, whereas the homogeneous case is characterized by a single mode. In contrast, the strain heterogeneity does not change significantly the postreversal oscillations as well as the equilibrium configuration for a given mean strain. These results are strongly relevant for a broad magnetism community working in the field of curvilinear magnetism, shapeable magnetoelectronics, and straintronics. [ABSTRACT FROM AUTHOR]

Controlling the chiral degree of freedom in matter has long been an important issue for many fields of science. The spin-spiral order, which exhibits a strong magnetoelectric coupling, gives rise to chirality irrespective of the atomic arrangement of matter. Here, we report the resonantly enhanced natural optical activity on the electrically active magnetic excitation, that is, electromagnon, in multiferroic cupric oxide. The electric field control of the natural optical activity is demonstrated through magnetically induced chirality endowed with magnetoelectric coupling. These optical properties inherent to multiferroics may lead to optical devices based on the control of chirality. [ABSTRACT FROM AUTHOR]

In this work, magnetoelectric properties of a co-sintered bilayered composite of non-lead based piezoelectric 0.97(Bi0.5Na0.5TiO3)-0.03(K0.47Na0.47Li0.06Nb0.74Sb0.06Ta0.2O3) and magnetostrictive Co0.6Zn0.4Fe1.7Mn0.3O4 are presented. Similar optimal sintering conditions of the individual components lead to a very clean interface as evidenced in the scanning electron microscopy, angle dispersive X-ray diffraction, and energy-dispersive X-ray (EDX) results. Clean interface results in strong intimate mechanical coupling between both components and causes a maximum transfer of induced strain, leading to a large magnetoelectric coupling ~142 mV/cm.Oe measured in longitudinally magnetized-transversely polarized configuration (L-T mode). Remnant polarization ~32 μC/cm2, remnant magnetization ~0.50 emu/g, and sufficiently high self biased magnetoelectricity ~135 mV/cm Oe (L-T mode) were observed for this composite. [ABSTRACT FROM AUTHOR]

Multiferroic nanostructures of Ni0.6Zn0.4Fe2O4-BaTiO3 (NZF/BT) have been prepared by two synthesis routes, i.e., chemical combustion (CNZF/BT) and hydrothermal (HNZF/BT). The synthesis of CNZF/BT results in nanoparticles of average size 4 nm at 500 °C annealing. However, the synthesis of HNZF/BT with hydrolysis temperature 180 °C/48 h shows nanowires of diameter 3 nm and length >150 nm. A growth mechanism in the fabrication of nanoparticles and wires is given. X-ray diffraction is used to identify the crystalline phase. The transmission electron microscopy shows the dimensions of NZF/BT nanostructures. The ferromagnetism, ferroelectricity, and magnetoelectric coupling show more enhancements in HNZF/BT nanowires than CNZF/BT nanoparticles. The observed polarization depends upon shape of nanostructures, tetragonal phase, and epitaxial strain. The tension induced by the surface curvature of nanowire counteracts the near-surface depolarizing effect and meanwhile leads to unusual enhancement of polarization. The ferromagnetism depends upon superficial spin canting, spin pinning of nanocomposite, and oxygen vacancy clusters. The magnetoelectric coefficient as the function of applied dc magnetizing field under ac magnetic field 5 Oe and frequency 1093 Hz is measured. The nanodimensions of NZF/BT are observed dielectric constant up to 120 MHz. The optical activity of NZF/BT nanostructures is shown by Fluorescence spectra. [ABSTRACT FROM AUTHOR]

In this Letter, we investigate the magnetic and multiferroic properties of a W-type hexaferrite SrZn1.15Co0.85Fe16O27. Due to the strong planar contribution to the anisotropy provided by Co2+ ions, this hexaferrite shows a spin reorientation transition from easy-axis to easy-cone at 302K, which is different from the onset temperature of ferroelectric polarization, 275K. By applying magnetic field, a remarkable drop of polarization is observed, suggesting a large magnetoelectric effect in this multiferroics. The difference between spin reorientation and ferroelectric phase transition temperature as well as the origin of magnetoelectric effect are discussed. [ABSTRACT FROM AUTHOR]

In this Letter, we investigate the magnetic and multiferroic properties of a W-type hexaferrite SrZn1.15Co0.85Fe16O27. Due to the strong planar contribution to the anisotropy provided by Co2+ ions, this hexaferrite shows a spin reorientation transition from easy-axis to easy-cone at 302K, which is different from the onset temperature of ferroelectric polarization, 275K. By applying magnetic field, a remarkable drop of polarization is observed, suggesting a large magnetoelectric effect in this multiferroics. The difference between spin reorientation and ferroelectric phase transition temperature as well as the origin of magnetoelectric effect are discussed. [ABSTRACT FROM AUTHOR]

For the tri-layer symmetric magnetoelectric (ME) laminated composites made of giant magnetostrictive materials and piezoelectric materials, we chose the nonlinear magnetostrictive constitutive with variable coefficients and the linear piezoelectric constitutive to obtain the vibration equation for the laminated composites. The surface force and displacement speed were equivalent to the circuit voltage and current in the equivalent circuit for the laminated composites. According to the equivalent circuit, a model of the static magnetoelectric field coefficient for the strong nonlinear thermo-magneto-electro-mechanical coupling was obtained. Without considering the pre-stress, the comparisons of the static ME coefficient versus temperature curves for the experimental and theoretical results were in good agreement both qualitatively and quantitatively for low and moderate magnetic fields. The theoretical results were smaller than the experimental results under high magnetic fields. This model was adopted to predict variations in the ME coefficients in the laminated composites under different bias magnetic fields, temperatures, and stresses. This showed that the laminated composites had the strongest magnetoelectric effect at 0 °C; a large compressive stress effectively suppressed the magnetoelectric effect attenuation caused by high temperatures; an appropriate tensile stress improved the maximum magnetoelectric coefficient and lowered its bias magnetic field near room temperature. These results provide a theoretical basis for the design and application of high-performance and miniaturized magnetoelectric devices, operating under extreme temperature conditions. [ABSTRACT FROM AUTHOR]

Laminated magnetoelectric (LME) thin films have the ability of conversion between electric and magnetic energies. However, when coated on stiff substrates, their magnetoelectric (ME) effect will be suppressed evidently due to the clamping effect of substrates. In order to reduce the clamping effect, a compliant buffer layer method is proposed in this paper which can help in inducing wrinkles of LME thin films and effectively enhance the ME effect of clamped ones. A LME wrinkling model which is a combination of LME plate theory and energy analysis method is proposed to predict the wrinkling behaviours of LME thin films bonded on compliant buffer-layers with finite thickness. The theoretical results show that the wrinkled state is one of necessary conditions of ME effect of such LME thin film/buffer-layer/substrate system and the ME effect of this system can be evidently influenced by several factors: the pre-strain in the laminated thin film, the thickness and stiffness of buffer layer. Finite element method (FEM) simulations are also conducted to verify the proposed model. Both theoretical and numerical results show that the thin films bonded on more compliant or thicker buffer layer have better ME effect, and the compressive pre-strain in LME thin films can also help in inducing wrinkles and enhancing the ME effect. [ABSTRACT FROM AUTHOR]

A low-frequency magnetoelectric (ME) response model of magnetostrictive/piezoelectric laminate composites based on multi-parameter analysis is presented. This model, taken the shear effect as the basis, analyzes the stress and strain of the magnetostrictive and piezoelectric layers by the stress function. The interlayer shear stress and the low-frequency ME response characteristics of ME laminate composites are obtained by using Hamilton principle of minimum energy and in consideration of the influence of stored magnetic field energy of magnetostrictive layer. The theoretical results show that the ME voltage coefficient is related with the magnetic permeability, Poisson ratio, magnetomechanical coupling coefficient, thickness ratio of magnetostrictive material and the Poisson ratio and electromechanical coupling coefficient of piezoelectric material. The influence of these parameters is analyzed. The experimental results show that analytical results are also compared to experimental test data with excellent correlation and their errors are less than 6%. [ABSTRACT FROM AUTHOR]

• Innumerable spin gapless points identified in the stable materials Mg 2 VO 4. • Multiple nodal rings located exactly at Fermi level with all hourglass shape dispersions. • Very clean spin gapless band structures and nodal ring states with no other band interferences. • Strong robustness against both the spin orbit coupling effect and strain conditions. • A novel concept of nodal ring spin gapless semiconductor is defined. Spin gapless semiconductors (SGSs) and nodal ring states (NRSs) have aroused great scientific interest in recent years due to their unique electronic properties and high application potential in the field of spintronics and magnetoelectronics. Since their advent, all SGSs and NRSs have been predicted in independent materials. In this work, we proposed a novel type of material, nodal ring spin gapless semiconductor (NRSGS), which combines both states of the SGSs and NRSs. The synthesized material Mg 2 VO 4 has been detailed with band structure analysis based on first principle calculations. Obtained results revealed that there are gapless crossings in the spin-up direction, which are from multiple topological nodal rings located exactly at the Fermi energy level. Mg 2 VO 4 combines the advantages inherited from both NRSs and SGSs in terms of the innumerable gapless points along multiple nodal rings with all linear dispersions and direct contacts. In addition, Mg 2 VO 4 also shows strong robustness against both the spin orbit coupling effect and strain conditions. For the first time, we propose the concept of an NRSGS, and the first such material candidate Mg2VO4 can immediately advance corresponding experimental measurements and even facilitate real applications. [ABSTRACT FROM AUTHOR]

Abstract 4D printing is a newly emerging technique that shows the capability of additively manufacturing structures whose shape, property, or functionality can controllably vary with time under external stimuli. However, most of the existing 4D printed products only focus on the variation of physical geometries, regardless of controllable changes of their properties, as well as practical functionality. Here, a material combination concept is proposed to construct 4D printed devices whose property and functionality can controllably vary. The 4D printed devices consist of conductive and magnetic parts, enabling the integrated devices to show a piezoelectric property even neither part is piezoelectric individually. Consequently, the functionality of the devices is endowed to transfer mechanical to electrical energy based on the electromagnetic introduction principle. The working mechanism of 4D printed devices is explained by a numerical simulation method using Comsol software, facilitating further optimization of their properties by regulating diverse parameters. Due to the self‐powered, quick‐responding, and sensitive properties, the 4D printed magnetoelectric device could work as pressure sensors to warn illegal invasion. This work opens a new manufacturing method of flexible magnetoelectric devices and provides a new material combination concept for the property‐changed and functionality‐changed 4D printing.

A generalized lumped element modeling for electrically and magnetically dual-tunable coupled microstrip filters is established through the introduction of the coupling factor which stands for coupling between magnetoelectric layered structure and the input/output microstrip. Then, the lumped element modeling for an existing filter is established and used to predict the electric and magnetic tunability of the filter that manifests as a shift in pass-band. The results have a good consistency with the experimental data and the electromagnetic simulation results in quality and quantity. Then the effects of applied electric field, microstrip's size, substrate's size, and the ferrite-piezoelectric layered structure's size on the filter performance are analyzed by the lumped element modeling. The predicted results show that the performance of the filter can be effectively improved through the increase of microstrip's length and the structure's thickness in a certain range, or the decrease of structure's width and length and the distance between the microstrip and the structure appropriately. [ABSTRACT FROM AUTHOR]

In this paper, we show that electrically excited mechanical resonances can be tuned with a single dc magnetic field in strip-ring magnetoelectric composites, namely, ferrite-lead zirconate titanate (PZT) and nickel-zinc (Ni-Zn) ferrite. A theoretical model is presented to describe the magnetically tuned electromechanical resonances in the piezoelectric-magnetostrictive heterostructure, where the piezoelectric and magnetostrictive phases are coupled through normal stresses instead of shear stresses, which usually act in layered composites. As we have used only dc magnetic field that tuned electromechanical resonances, the adjustment manner can simplify application in transducers for magnetoelectric energy conversion. [ABSTRACT FROM AUTHOR]

Lead free magneto electrics with a strong sub resonant (broad frequency range) magneto electric coupling coefficient (MECC) is the goal of the day which can revolutionise the microelectronics and microelectromechanical systems (MEMS) industry. We report giant resonant MECC in lead free nanograined Barium Titanate-CoFe (Alloy)-Barium Titanate [BTO-CoFe-BTO] sandwiched thin films. The resonant MECC values obtained here are the highest values recorded in thin films/multilayers. Sub-resonant MECC values are quite comparable to the highest MECC reported in 2-2 layered structures. MECC got enhanced by two orders at a low frequency resonance. The results show the potential of these thin films for transducer, magnetic field assisted energy harvesters, switching devices, and storage applications. Some possible device integration techniques are also discussed. [ABSTRACT FROM AUTHOR]

This paper describes studies of the effect of electron tunneling on magnetic switching in single Co particles large enough to exhibit continuous energy spectra at mK-temperatures. The ground state spin S0, in units of h, is estimated to be ∼104 in these particles. The magnetic switching field decreases versus tunneling current, with the effective magnetic temperature at the switching field smaller by factor of 2-3 compared to that found previously in smaller Co particle where S0∼103. We show that this relatively weak size dependence confirms that the magnetic tunneling transitions in the particle are driven by mesoscopic fluctuations in magnetic anisotropy energy. [ABSTRACT FROM AUTHOR]

We employ ab-initio electronic structure calculations to study 60 LiMgPdSn-type (also known as LiMgPdSb-type) quaternary Heusler compounds. All compounds obey the Slater-Pauling rule with diverse electronic and magnetic properties. 41 compounds are found to be half-metals, 8 spin-gapless semiconductors, and 9 semiconductors. CoVTiAl and CrVTiAl compounds are identified as ferromagnetic and antiferromagnetic semiconductors, respectively, with large energy gaps in both spin directions. All magnetic compounds are expected to have high Curie temperatures making them suitable for spintronics/magnetoelectronics applications. [ABSTRACT FROM AUTHOR]

By constructing dynamic equations including electrons, holes and their pair densities, we calculate the magnetoconductance (MC) and the magnetoelectroluminescence (MEL) separately. It is indicated that MC and MEL may result from different response on the applied magnetic field. MC is from the scattering of polarons by magnetic field related triplet excitons, while MEL is mainly from magnetic field related conversion between singlet and triplet electron-hole pairs. Furthermore, we discuss the relation between MC and MEL. The theoretical calculations are well consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Driving nanomagnets by spin-polarized currents offers exciting prospects in magnetoelectronics, but the response of the magnets to such currents remains poorly understood. We show that an averaged equation describing the diffusion of energy on a graph captures the low-damping dynamics of these systems. From this equation we obtain the bifurcation diagram of the magnets, including the critical currents to induce stable precessional states and magnetization switching, as well as the mean times of thermally assisted magnetization reversal in situations where the standard reaction rate theory of Kramers is no longer valid. These results match experimental observations and give a theoretical basis for a Néel-Brown-type formula with an effective energy barrier for the reversal times. [ABSTRACT FROM AUTHOR]

The ab initio calculations based on the density functional theory (DFT) using the self-consistent full potential linearized augmented plane wave (FPLAPW) method were performed to explore the electronic structures, magnetic and thermoelectric properties of quaternary alloys RbCaCZ (Z = P, As, Sb) with quaternary Heusler structure. Results showed that FM-Y3 is the most favorable atomic arrangement. All the compounds are found to be half-metallic ferromagnetic materials with an integer magnetic moment of 2.00 µB, which predominantly derives from the strong spin polarization of p channels of C hybridized with Z elements. The predicted minority (half-metallic) band gaps were found to be 1.86 (0.87), 1.72 (0.78), and 1.78 (0.71) eV for Z = P, As, and Sb, respectively. Thermoelectric properties of the RbCaCZ (Z = P, As, Sb) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds demonstrates higher figure of merit. The half-metallic structures of these compounds with large band gaps and adequate Seebeck coefficients mean that they are suitable for use in spintronic and thermoelectric device applications. [ABSTRACT FROM AUTHOR]

This study proposes an input interface based on a magnetic tunnel junction (MTJ) to initialise the magnetisation directions of all‐spin logic (ASL) circuits. It is convenient to input logic 0 and logic 1 to ASL circuits by changing the current direction into the MTJ. The impacts of current density, tunnel magneto‐resistance (TMR), and resistance–area product (RA) on the input interface are studied. The results indicate that smaller TMR and RA of the materials are helpful in reducing the energy dissipation of the input interface without increasing the delay time, and the current density has a large range of options. Moreover, two kinds of output structures, single‐input multi fan‐out (SIMF) and multi‐input single fan‐out (MISF), are proposed to provide signals for subsequent ASL circuits. It is found that the SIMF structure is suitable for the condition of fewer output terminals, but the MISF structure is especially useful for large‐scale ASL circuits that contain many identical input ports. The above‐mentioned conclusions can provide guidelines for optimising the device materials and output structures of ASL circuits. [ABSTRACT FROM AUTHOR]

The present paper implements the novel generalized (G'/G)-expansion approach in solving the most popular nonlinear wave equations such as the longitudinal wave motion equation in a magneto-electro-elastic circular rod and the Drinfeld-Sokolov-Wilson equation. In this regard, we investigate the method to obtain new type of wave solutions of the studied models. New exact wave solutions are derived in the structures such as singular bright solition, compaction, singular bright periodic wave solitions, singular dark solition and singular dark periodic wave solition solutions of the studied models by using the novel generalized (G'/G)-expansion scheme. To draw the physical aspect of the got results, the 2D, 3D surfaces as well as the relating the contour plot surfaces of some acquired results are performed. The obtained results can assist to illustrate the physical application of the examined models and other nonlinear physical models appearing in mathematical physics. [ABSTRACT FROM AUTHOR]

This paper reports on frequency tunable MEMS magnetoelectric (ME) sensors. Different designs are studied in respect to ME voltage coefficient and frequency tunability. Compared to state-of-the-art ME sensors, the presented ME resonators display a highly reversible and linear frequency tuning, enabled by applying a DC voltage to piezoelectric actuators. A frequency shift of up to 0.2 Hz V−1 is demonstrated for a sensor with a limit of detection of 128 pT/Hz0.5 at resonance frequency of 13 kHz. This sensor type is of particular interest for vector field sensors and sensor arrays in bio-magnetic applications, where sensors with either identical resonance frequencies or precisely defined frequency spacing are required. [ABSTRACT FROM AUTHOR]

Simultaneous effects of Na and Mn co-dopants on either site of LaFeO3 on the structural, magnetic, and low-temperature dielectric properties are studied in detail. The nanoparticles are prepared using a modified wet chemical route. The X-ray diffraction pattern is consistent with the formation of monophase with the distorted orthorhombic crystal structure. The average particle size is measured to be around 34 nm. The temperature and field dependent magnetization data reveals a drastic magnetic phase change of the modified co-doping system than LaFeO3 which is otherwise canted antiferromagnetic. This phase change is attributed to the mixed valence state of Mn ions present in the system due to substitutions. Several orders of change in the dielectric order parameter are found in the doped system. The low-temperature impedance spectra of the doped samples show dominant grain boundary relaxation as evidenced by modulus spectra. The conduction mechanism has been identified by calculating activation energies of relaxation from grain boundary and grain resistances as well as from ac conductivity analysis which are in good agreement. The typical calculated values are evidence of small polaronic hopping conduction mechanism in the sample. [ABSTRACT FROM AUTHOR]

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4D printing is a newly emerging technique that shows the capability of additively manufacturing structures whose shape, property, or functionality can controllably vary with time under external stimuli. However, most of the existing 4D printed products only focus on the variation of physical geometries, regardless of controllable changes of their properties, as well as practical functionality. Here, a material combination concept is proposed to construct 4D printed devices whose property and functionality can controllably vary. The 4D printed devices consist of conductive and magnetic parts, enabling the integrated devices to show a piezoelectric property even neither part is piezoelectric individually. Consequently, the functionality of the devices is endowed to transfer mechanical to electrical energy based on the electromagnetic introduction principle. The working mechanism of 4D printed devices is explained by a numerical simulation method using Comsol software, facilitating further optimization of their properties by regulating diverse parameters. Due to the self‐powered, quick‐responding, and sensitive properties, the 4D printed magnetoelectric device could work as pressure sensors to warn illegal invasion. This work opens a new manufacturing method of flexible magnetoelectric devices and provides a new material combination concept for the property‐changed and functionality‐changed 4D printing. [ABSTRACT FROM AUTHOR]

A filtering magnetoelectronic dipole antenna (MEDA) with quasi-elliptic gain response and wide operating band is investigated. Different from the conventional MEDA, the antenna studied here is fed by fork-shaped microstrip line aperture-coupled excitation. The intrinsic radiation null of the MEDA at the lower passband edge is utilized, and a mathematical model is first put forward to demonstrate its working mechanism. Four driven stubs connected to the shorted walls of MEDA are used to excite the planar dipole arms. The parasitic inductor and the coupling capacitor introduced by driven stubs form an equivalent low-pass filter network, leading to a radiation null at higher frequency. Furthermore, a third radiation null is generated by introducing two quarter-wavelength U-shaped shorted stubs to improve the out-of-band suppression. Besides, due to the introduction of multiple coupling structure, including the fork-shaped microstrip line coupling slot and driven stubs, a wide operating band can be realized while maintaining a low profile of 0.15 wavelength. The experimental results show that an impedance bandwidth of 53.5% (2.95–5.1 GHz) is achieved and an out-of-band suppression level higher than 17.9 dB is obtained. What is more, an average gain of 8 dBi and good radiation patterns are realized over the whole operating band. [ABSTRACT FROM AUTHOR]

We present the fabrication and characterization of an array of microbridge-structured magnetoelectric (ME) thin film sensors which are constructed by an ME composite consisting of a 1 $\mu \text{m}$ PZT film and a 1 $\mu \text{m}$ amorphous FeCoSiB film deposited on a partially thinned Si substrate. Characterization of the sensor showed a large ME coefficient of $16.87~\text {V/cm}\cdot \text {Oe}$ in resonance at 7.9 kHz without a charge amplifier. The sensitivity was enhanced by 1.65 times when three identical sensors were connected in series. The resonant frequency of the sensor was precisely regulated by adjusting the etched area of the substrate, and the 3 dB bandwidth of the resonant frequency was doubled after two adjusted sensors were connected in parallel. [ABSTRACT FROM AUTHOR]