Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer Process

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering.In recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations.Moreover,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical phenomena.In this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with 45.and 0.twist angles were assembled via water-etching and transfer process.The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO<110>.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°Sample.The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial anisotropy.This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

Clinical efficacy of magnetic vibration magnetoelectric therapy in the treatment of chronic prostatitischronic pelvic pain syndrome

BACKGROUND The prominent symptoms of chronic pelvic pain syndrome(CPPS)are urogenital pain,lower urinary tract symptoms,psychological problems,and sexual dysfunction.Traditional pharmacological treatments have poor efficacy and more untoward reaction and complications.Magnetic vibration magnetoelectric therapy is a non-invasive form of physiotherapy.Nevertheless,its effectiveness in improving urinary discomfort and relieving pain in patients requires further exploration.AIM To investigate the clinical efficacy of the magnetic vibration magnetoelectric therapy instrument in the treatment of chronic prostatitis(CP)/CPPS.METHODS Seventy patients with CP/CPPS were collected from the outpatient clinic and ward of the Department of Male Medicine,Jiangsu Province Hospital of Traditional Chinese Medicine,and were treated with magnetic vibration magnetoelectric therapy once a day for a period of 14 d.National Institutes of healthchronic prostatitis symptom index(NIH-CPSI),international index of erectile function 5(IIEF-5),premature ejaculation diagnostic tool(PEDT),generalized anxiety disorder(GAD),patient health questionnaire,the pain catastrophizing scale(PCS)and traditional Chinese medicine syndrome(TCMS)scores were performed before and after treatment.RESULTS The total effective rate of treatment was 58.5%,and the total NIH-CPSI score,pain symptoms,voiding symptoms,quality of life,IIEF-5,PEDT,GAD,PCS and TCMS scores all decreased significantly(P<0.05).CONCLUSION Magnetic vibration magnetotherapy is effective in improving urinary discomfort,relieving pain,improving quality of life,improving sexual dysfunction and relieving negative emotions such as anxiety in patients with CP/CPPS.

Magnetostatic Coupling in CoFe204/Pb（Zr0.53Ti0.47）O3 Magnetoelectric Composite Thin Films of 2-2 Type Structure

CoFe204/Pb（Zr0.53Ti0.47）O3 （CFO/PZT） magnetoelectric composite thin films of 2-2 type structure had been prepared onto Pt/Ti/SiO2/Si substrate by a sol-gel process and spin coat- ing technique. The structure of the prepared thin film is substrate/PZT/CFO/PZT/CFO. Two CFO ferromagnetic layers are separated from each other by a thin PZT layer. The upper CFO layer is magnetostatically coupled with the lower CFO layer. Subsequent scan- ning electron microscopy （SEM） investigations show that the prepared thin films exhibit good morphologies and compact structure, and cross-sectional micrographs clearly display a multilayered nanostructure of multilayered thin films. The composite thin films exhibit both good magnetic and ferroelectric properties. The spacing between ferromagnetic layers can be varied by adjusting the thickness of intermediate PZT layer. It is found that the strength of magnetostatic coupling has a great impact on magnetoelectric properties of composite thin films, i.e., the magnetoelectric voltage coefficient of composite thin film tends to increase with the decreasing of pacing between two neighboring CFO ferromagnetic layers as a result of magnetostatic coupling effect.

Lumped-equivalent circuit model for multi-stage cascaded magnetoelectric dual-tunable bandpass filter

A lumped-equivalent circuit model of a novel magnetoelectric tunable bandpass filter, which is realized in the form of multi-stage cascading between a plurality of magnetoelectric laminates, is established in this paper for convenient analysis.The multi-stage cascaded filter is degraded to the coupling microstrip filter with only one magnetoelectric laminate and then compared with the existing experiment results. The comparison reveals that the insertion loss curves predicted by the degraded circuit model are in good agreement with the experiment results and the predicted results of the electromagnetic field simulation, thus the validity of the model is verified. The model is then degraded to the two-stage cascaded magnetoelectric filter with two magnetoelectric laminates. It is revealed that if the applied external bias magnetic or electric fields on the two magnetoelectric laminates are identical, then the passband of the filter will drift under the changed external field; that is to say, the filter has the characteristics of external magnetic field tunability and electric field tunability. If the applied external bias magnetic or electric fields on two magnetoelectric laminates are different, then the passband will disappear so that the switching characteristic is achieved. When the same magnetic fields are applied to the laminates, the passband bandwidth of the two-stage cascaded magnetoelectric filter with two magnetoelectric laminates becomes nearly doubled in comparison with the passband filter which contains only one magnetoelectric laminate. The bandpass effect is also improved obviously. This research will provide a theoretical basis for the design, preparation, and application of a new high performance magnetoelectric tunable microwave device.

Magnetoelectric effect in layered composites with arc shape

Magnetoelectric （ME） layered Ni/PZT/Ni composites with arc shape have been prepared by using electroless deposition. The ME effect is measured by applying both constant and alternating magnetic fields in longitudinal and transverse directions. The longitudinal ME voltage coefficient is much larger than the transverse one. With the increase of arc length or decrease of curvature, the resonance frequency of layered arc Ni/PZT/Ni composites gradually decreases, while the maximum of the ME voltage coefficient of the composites increases monotonously. The influence of the arc length and the curvature on ME coupling is discussed. The flat interface between the ferromagnetic and the piezoelectric phases in layered ME composites is believed to provide large ME voltage coefficient.

Insights into the regulation mechanism of ring-shaped magnetoelectric energy harvesters via mechanical and magnetic conditions

This paper presents a theoretical model for predicting and tuning magnetoelectric(ME)effect of ring-shaped composites,in which stress boundary conditions are empoyed and the multi-field coupling property of giant magnetostrictive materials are taken into account.A linear analytical solutions for the closed-and open-circuit ME voltages are derived simultaneously using mechanical differential equations,interface and boundary conditions,and electrical equations.For nonlinear ME coupling effect,the nonlinear multi-field coupling constitutive equation is reduced to an equivalent form by expanding the strains as a Taylor series in the vicinity of bias magnetic field.Sequentially,the linear model is generalized to a nonlinear one involving the field-dependent material parameters.The results show that setting a stress-free condition is beneficial for reducing resonance frequency while applying clamped conditions on the inner and outer boundaries may improve the maximum output power density.In addition,performing stress conditions on one of the boundaries may enhance ME coupling significantly,without changing the corresponding resonance frequency and optimal resistance.When external stimuli like bias magnetic field and pre-stress are applied to the ring-shaped composites,a novel dual peak phenomenon in the ME voltage curve around resonance frequencies is revealed theoretically,indicating that strong ME coupling may be achieved within a wider bias field region.Eventually,the mutual coordination of the bias field and pre-stress may enhance ME coupling as well as tuning the resonance frequency,and thus is pivotal for tunable control of ME energy harvesters.The proposed model can be applied to design high-performance energy harvesters by manipulating the mechanical conditions and external stimuli.

Magnetoelectric effects in multiferroic Y-type hexaferrites Ba(0.3)Sr(1.7)CoxMg(2-x)Fe(12)O(22)

Y-type hexaferrites with tunable conical magnetic structures are promising single-phase multiferroics that exhibit large magnetoelectric effects. We have investigated the influence of Co substitution on the magnetoelectric properties in the Y-type hexaferrites Ba(0.3)Sr(1.7)CoxMg(2-x)Fe(12)O(22)(x = 0.0, 0.4, 1.0, 1.6). The spin-induced electric polarization can be reversed by applying a low magnetic field for all the samples. The magnetoelectric phase diagrams of BaBa(0.3)Sr(1.7)CoxMg(2-x)Fe(12)O(22) are obtained based on the measurements of magnetic field dependence of dielectric constant at selected temperatures. It is found that the substitution of Co ions can preserve the ferroelectric phase up to a higher temperature, and thus is beneficial for achieving single-phase multiferroics at room temperature.

Frequency dependence of the magnetoelectric effect in a magnetostrictive-piezoelectric heterostructure

The frequency dependence of the magnetoelectric effect in a magnetostrictive-piezoelectric heterostructure is theoretically studied by solving combined magnetic, elastic, and electric equations with boundary conditions. Both the mechanical coupling coefficient and the losses of the magnetostrictive and piezoelectric phases are taken into account. The numerical result indicates that the magnetoelectric coefficient and the resonance frequency are determined by the mechanical coupling coefficient, losses, and geometric parameters. Moreover, at the electromechanical resonance frequency, the module of the magnetoelectric coefficient is mostly contributed by the imaginary part. The relationship between the real and the imaginary parts of the magnetoelectric coefficient fit well to the Cole–Cole circle. The magnetostrictive-piezoelectric heterostructure has a great potential application as miniature and no-secondary coil solid-state transformers.

Design of driving wheel speed test device based on magnetoelectric sensor

In order to study the transmission efficiency of engine and optimize the structure of driving wheel,the rotational speed storage test device of driving wheel in tracked vehicle based on magnetoelectric sensor was designed.The device consisted of a mounting bracket,a sensor and a tester.The mounting bracket was installed in vehicle body after fixing the tester and sensor to mounting bracket beside the driving wheel.Using the storage test instrument,the wireless trigger technology was applied to synchronously record and stored the rotational speed data of the driving wheel in tracked vehicle.After the experiment was finished,the data was read out through the upper computer.Both valid data and satisfactory results were obtained through both simulated and actual vehicle tests.

Exact 3D Thermoelastic Solutions for a Penny-Shaped Crack in an Infinite Magnetoelectric Medium

Exact solutions of three-dimensional(3D)crack problems are much less in number than those of two-dimensional ones,especially for multi-field coupling media exhibiting a certain kind of material anisotropy.An exact3Dthermoelastic solution has been reported for a uniformly heated penny-shaped crack in an infinite magnetoelectric space,with impermeable electromagnetic conditions assumed on the crack faces.Exact 3Dsolutions for the penny-shaped crack subjected to uniform or point temperature load are further presented here when the crack faces are electrically and magnetically permeable.The solutions,obtained by the potential theory method,are exact in the sense that all field variables are explicitly derived and expressed in terms of elementary functions.Along with the previously reported solution,the limits or bounds of the stress intensity factor at the crack-tip for a practical crack can be identified.

Magnetic and Electric Charges in Physics and Technology of Electromagnetic and Magnetoelectric Induction

Experimental and theoretical researches performed by the author (period: 1969-present) showed that magnetic spinor particles (magnetic charges) are real structural components of atoms and substance and immediate sources of all magnetic fields and magnetic manifestations in Nature. Magnetic charges, that constitute together with electrical charges atomic shells got of title: magnetons and antimagnetons (respectively with charges g&minus;and g+ under fundamental condition: g = e). Furthermore, in addition to participating in structures of atomic shells, the magnetic charges exist in potential and even in real zones conduction of solids. The magnetic and electric spinor particles in atoms and substance exist in form such of the spinor associations as the magnetic and electric bispinors. Under influence of external magnetic field in conductor being implemented polarization of magnetic bispinors with formation of magnetic dipoles. Internal fields magnetic dipoles is directed against an external magnetic field and is a simple explanation of such a physical manifestation as diamagnetism. During the rotation of these dipoles in the conductor are formed of the vortex magnetic dipole fields, which and create an electromotive force, i.e. are responsible for the electromagnetic induction. Author proposed new magneto-electric technology called the magnetoelectric induction, as the result of which the permanent current of magnetic charges is created. However, such currents may be implemented solely in the superconductors. In the article presented the main reasons which more hundred year old hinder recognition and technical use of the real magnetic charges and their currents what considerably slow down the global scientific and technological progress.

Magnetoelectric effects in multiferroic laminated plates with imperfect interfaces

Two-dimensional （2D） equations for multiferroic （MF） laminated plates with imperfect interfaces are established in this paper. The interface between two adjacent sublayers, which are not perfectly bonded together, is modeled as a general spring-type layer. The mechanical displacements, and the electric and magnetic potentials of the two adjacent layers are assumed to be discontinuous at the interface. As an example, the influences of imperfect interfaces on the magnetoelectric （ME） coupling effects in an MF sandwich plate are investigated with the established 2D governing equations. Numerical results show that the imperfect interfaces have a significant impact on the ME coupling effects in MF laminated structures.

Dynamical anisotropic magnetoelectric effects at ferroelectric/ferromagnetic insulator interfaces

The interfacial magnetoelectric interaction originating from multi-orbital hopping processes with ferroelectricassociated vector potential is theoretically investigated for complex-oxide composite structures.Large mismatch in the electrical permittivity of the ferroelectric and ferromagnetic materials gives rise to giant anisotropic magnetoelectric effects at their interface.Our study reveals a strong linear dynamic magnetoelectric coupling which genuinely results in electric control of magnetic susceptibility.The constitutive conditions for negative refractive index of multiferroic composites are determined by the analysis of light propagation.

Magnetoelectric spin–orbit logic

Nature, 565, 35–42 (2019)In the last decade, transistor scaling has been enabled by direct improvements to the carrier transport and superior electrostatic control. Despite the successful scaling in the size of transistors, voltage and frequency scaling have slowed. In response, a considerable effort to invent, demonstrate and benchmark beyond-CMOS devices got underway.

The Electric-Field Controllable Non-Volatile 35° Rotation of Magnetic Easy Axis in Magnetoelectric CoFeB/(001)-Cut Pb(Mg_(1/3)Nb_(2/3))O_3-25%PbTiO_3 Heterostructure

Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical poling states is demonstrated in C040Fe40B20//（001）-cut Pb（Mgl/3Nb2/3）O3-25PbTiO3 （PMN-PT）. The specific magneto- electric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the （001）-cut PMN-PT substrate.

Modulation of magnetic properties and enhanced magnetoelectric effects in MnW_(1-x)Mo_xO_4 compounds

In this letter, we investigate the magnetic and ferroelectric properties of polycrystalline MnW1-xMoxO4 （x = 0, 0.05, 0.10, 0.20） compounds. The substitution of nonmagnetic Mo6＋ ions for W6＋ ions modifies the magnetic transition tem- peratures of MnW1-xMoxO4 by changing the Mn-O-Mn bond. As a result, distinct ferroelectric properties and enhanced magnetoelectric effects are observed in Mo6＋-doped MnWO4 compounds. The effects of substitution of Mo6＋ ions on magnetic properties and magnetoelectric coupling are discussed.

Frequency-dependent magnetoelectricity of CoFe_2O_4-BaTiO_3 particulate composites

CoFe2O4-BaTiO3 particulate composites were prepared by wet ball milling method,their magnetoelectric（ME） effect was studied as a function of their constituents and modulation frequency.The results show that the ME coefficient increases as a function of modulation frequency from 400 to 1000 Hz and the ME characteristics of ME curves are also modified because the electrical conductivity of the CoFe2O4 phase is sensitive to the increase in frequency between 400 and 1 000 Hz.The third phase Ba2Fe2O5 formed during the sintering tends to reduce the ME effect.

Enhanced ferromagnetism and magnetoelectric response in quenched BiFeO3-based ceramics

The piezoelectric,ferromagnetism,and magnetoelectric response of BiFeO3-BaTiO3 ceramics with the compositions around the morphotropic phase boundary(MPB)of the solid solution are systematically investigated after the ceramics have been quenched from a high temperature.We find that the ferromagnetism of the quenched ceramics is greatly enhanced.An enhanced piezoelectric response d33 larger than 200 pC/N,which could be sustained up to 350℃,is measured.As a result of enhanced ferromagnetism and piezoelectric response,a large magnetoelectric response^1.3 V/cm·Oe(1 Oe=79.5775 A·m^-1)is obtained near the mechanical resonance frequency of the quenched ceramic samples.Our research also shows that in addition to the ferromagnetism and piezoelectric response,the mechanical quality factor is another important parameter to achieve high magnetoelectric response because the physical effects are coupled through mechanical interaction in BiFeO3-based materials.Our work suggests that quenching is an effective approach to enhancing the magnetoelectric response of BiFeO3-based materials and the materials belong to single-phase multiferroic materials with high magnetoelectric response.

Magnetoelectric effect in multiferroic NdMn2O5

We have measured the dielectric constant for NdMn2O5 in an external magnetic field to map out the magnetoelectric phase diagram. The phase diagram corresponds well with the previously reported data of neutron diffraction and magnetic susceptibility. Our main finding is the observation of a dielectric anomaly in the low temperature phase with a strong magnetoelectric effect, which is attributed to the independent Nd^3＋ ordering. Moreover, the absence of the dielectric anomaly in the paramagnetic phase is discussed, keeping in view the exchange interaction and its dependence on the rareearth R^3＋ ionic radius.

Enhancement in the Response of Pb(Zr,Ti)O_3/Terfenol-D/Metglas Magnetoelectric Laminate Composites

The magnetic field response results on a five-layer structure given as Metglas/Terfenol-D/ Pb（Zr,Ti）O3frerfenol-D/Metglas were reported. Due to its high permeability, Metglas can be incorporated as the third phase into conventional Pb（Zr, Ti）OJTerfenol-D laminates, which results in a stronger magnetoelectric（ME） response. The increase in Metglas thickness significantly influences the ME response as well. The ME voltage coefficient for a structure with a 150 grn thick Metglas layer on both sides of Terfenol-D/Pb（Zr, Ti）O3 laminates at 1 kHz was found to be 1.2 V/cmOe at dc magnetic bias field of 590 Oe under an ac magnetic drive of 1 Oe, which was notably higher in comparison to similar structures with other different Metglas thickness. Key words： laminates composites; magnetoelectric response; magnetic field; Metglas thickness