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 ...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.展开更多
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 pap...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.展开更多
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 longitudina...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.展开更多
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 magn...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.展开更多
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 magnetoele...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.展开更多
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 condition...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.展开更多
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 sourc...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−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.展开更多
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,...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.展开更多
The interfacial magnetoelectric interaction originating from multi-orbital hopping processes with ferroelectricassociated vector potential is theoretically investigated for complex-oxide composite structures.Large mis...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.展开更多
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 trans...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.展开更多
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 ...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.展开更多
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 magn...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.展开更多
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 ...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.展开更多
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 diffract...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.展开更多
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 i...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展开更多
A polyvinylidene-fluoride(PVDF)-based magnetoelectric torque(MET) device is designed with elastic layer sandwiched by PVDF layers, and low-frequency MET effect is carefully studied. It is found that elastic modulu...A polyvinylidene-fluoride(PVDF)-based magnetoelectric torque(MET) device is designed with elastic layer sandwiched by PVDF layers, and low-frequency MET effect is carefully studied. It is found that elastic modulus and thickness of the elastic layer have great influences on magnetoelectric(ME) voltage coefficient(α(ME)) and working range of frequency in PVDF-based MET device. The decrease of the modulus and thickness can help increase the α ME. However,it can also reduce the working range in the low frequency. By optimizing the parameters, the giant α(ME) of 320 V/cm·Oe(1 Oe = 79.5775 A·m^-1 at low frequency(1 Hz) can be obtained. The present results may help design PVDF-based MET low-frequency magnetic sensor with improved magnetic sensitivity in a relative large frequency range.展开更多
Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures....Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.展开更多
We report on the magnetic and magnetoelectric properties of the Y-type hexaferrite BaSrZnMgFe12O22,which undergoes transitions from a collinear ferrimagnetic phase to a proper screw phase at 310 K and to a longitudina...We report on the magnetic and magnetoelectric properties of the Y-type hexaferrite BaSrZnMgFe12O22,which undergoes transitions from a collinear ferrimagnetic phase to a proper screw phase at 310 K and to a longitudinal conical phase at 45 K.Magnetic and electric measurements revealed that the magnetic structure with spiral spin order can be modified by applying a magnetic field,resulting in magnetically controllable electric polarization.It was observed that BaSrZnMgFe12O22 exhibits an anomalous magnetoelectric memory effect:the ferroelectric state can be partially recovered from the paraelectric phase with collinear spin structure by reducing magnetic field at 20 K.We ascribe this memory effect to the pinning of multiferroic domain walls,where spin chirality and structure are preserved even in the nonpolar collinear spin state.展开更多
We comparatively investigate the influence of various high-permeability alloys on the hysteretic and remanent res- onant magnetoelectric (ME) response in a composite of magnetostrictive nickel (Ni) and piezoelectr...We comparatively investigate the influence of various high-permeability alloys on the hysteretic and remanent res- onant magnetoelectric (ME) response in a composite of magnetostrictive nickel (Ni) and piezoelectric Pb(Zrl_x, Tix)O3 (PZT). In order to implement this comparative research, Co-based amorphous alloy (CoSiB), Fe-based nanocrystalline alloy (FeCuNbSiB) and Fe-based amorphous alloy (FeSiB) are used according to different magnetostriction (2s) and saturation magnetization (μtoMs) characteristics. The bending and longitudinal resonant ME voltage coefficients (αME,b and αME,1) are observed comparatively for CoSiB/Ni/PZT, FeCuNbSiB/Ni/PZT, and FeSiB/Ni/PZT composites. The experimental data indicate that the FeSiB/Ni/PZT composite has the largest remanent self-biased aME,b and aME,1 due to the largest magnetic grading of λs and μ0Ms in the FeSiB/Ni layer. When the number of FeSiB foils is four, the maximum remanent aME,b and aME,I at zero bias magnetic field are 57.8 V/cm·Oe and 107.6 V/cm·Oe, respectively. It is recommended that the high-permeability alloy is supposed to have larger λs and μ0Ms for obtaining a larger remanent self-biased ME responses in ME composite with high-permeability alloy.展开更多
An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles ...An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles calculations,we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets,which proves this idea in multiferroic heterostructures of ferromagnetic La TiO_(3)and ferroelectric Bi FeO_(3).The results show that the magnetic properties and two-dimensional electron gas concentrations of La TiO_(3)films can be controlled by changing the polarization directions of Bi FeO_(3).The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3 d electrons,which is the fundamental reason for the changing of magnetic properties.This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFB3201800)Natural Science Foundation of China (Grant Nos. U22A2019, 91964109, 52372123)+3 种基金State Key Laboratory for Mechanical Behavior of Materials (No. 20222405)Innovation Capability Support Program of Shaanxi (Grant No. 2021TD-12)National 111 Project of China (B14040)support from the Instrumental Analysis Center of Xi’an Jiaotong University
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11172285 and 11472259)the Natural Science Foundation of Zhejiang Province,China(Grant No.LR13A020002)
文摘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.
基金Project supported by the Natural Science Foundation of Jiangsu Province of China (Grant No. BK2010505)the Funding of Jiangsu Innovation Program for Graduate Education (Grant No. CX10B 099Z)
文摘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.
基金supported by the National Natural Science Foundation of China(Grant No.11702202)the Fundamental Research Funds for the Central Universities,China(Grant No.JB210410)the the National Natural Science Foundation of China(Grant No.51805401)。
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant No.51725104)Beijing Natural Science Foundation,China(Grant No.Z180009)。
文摘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.
文摘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.
文摘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−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.
基金supported by the National Natural Science Foundation of China(11672265,11202182,11272281,11621062,and 11321202)the Fundamental Research Funds for the Central Universities(2016QNA4026 and 2016XZZX001-05)the open foundation of Zhejiang Provincial Top Key Discipline of Mechanical Engineering
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474138 and 11834005)the Fund from the Ministry of Science and Technology of China(Grant No.CN-SK-8-4)+1 种基金the Science Foundation from the Slovak Academy of Sciences(Grant No.2/0059/17)the Science Fund from the Slovak Research and Development Agency(Grant No.APVV SK-CN-2017-0004)
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374010 and 11434009the Fundamental Research Funds for the Central Universities
文摘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.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB932304 and 2009CB929501)the National Natural ScienceFoundation of China(Grant Nos.11174130 and U1232210)
文摘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.
基金the National Natural Science Foundation of China(Grant Nos.51672261 and 51373161)the National Key Research and Development Program of China(Grant No.2017YFA0701301).
文摘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.
基金supported by Higher Education Commission(HEC)of Pakistan through its IRSIP scholarship program(IRSIP 27 PS 28)
文摘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.
基金Funded by the National Natural Science Foundation of China(No.51172080)
文摘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
基金supported by the National Natural Science Foundation of China(Grant Nos.51525103,51522105,and 11304326)the National Key Technology Research and Development Program of China(Grant No.2016YFA0201102)+1 种基金Ningbo Municipal Science and Technology Innovation Team,China(Grant No.2015B11001)the Ningbo Municipal Major Science and Technology Projects,China(Grant No.2015B11027)
文摘A polyvinylidene-fluoride(PVDF)-based magnetoelectric torque(MET) device is designed with elastic layer sandwiched by PVDF layers, and low-frequency MET effect is carefully studied. It is found that elastic modulus and thickness of the elastic layer have great influences on magnetoelectric(ME) voltage coefficient(α(ME)) and working range of frequency in PVDF-based MET device. The decrease of the modulus and thickness can help increase the α ME. However,it can also reduce the working range in the low frequency. By optimizing the parameters, the giant α(ME) of 320 V/cm·Oe(1 Oe = 79.5775 A·m^-1 at low frequency(1 Hz) can be obtained. The present results may help design PVDF-based MET low-frequency magnetic sensor with improved magnetic sensitivity in a relative large frequency range.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52072102 and 11775224)It was also partially funded through the Open Foundation of the Hefei National Laboratory for Physical Sciences at the Microscale(Grant No.KF2020002).
文摘Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.
基金supported by the National Natural Science Foundation of China(Grant Nos.11534015 and 51371193)
文摘We report on the magnetic and magnetoelectric properties of the Y-type hexaferrite BaSrZnMgFe12O22,which undergoes transitions from a collinear ferrimagnetic phase to a proper screw phase at 310 K and to a longitudinal conical phase at 45 K.Magnetic and electric measurements revealed that the magnetic structure with spiral spin order can be modified by applying a magnetic field,resulting in magnetically controllable electric polarization.It was observed that BaSrZnMgFe12O22 exhibits an anomalous magnetoelectric memory effect:the ferroelectric state can be partially recovered from the paraelectric phase with collinear spin structure by reducing magnetic field at 20 K.We ascribe this memory effect to the pinning of multiferroic domain walls,where spin chirality and structure are preserved even in the nonpolar collinear spin state.
基金supported by the National High Technology Research and Development Program of China(Grant No.2012AA040602)the National Natural Science Foundation of China(Grant No.61374217)
文摘We comparatively investigate the influence of various high-permeability alloys on the hysteretic and remanent res- onant magnetoelectric (ME) response in a composite of magnetostrictive nickel (Ni) and piezoelectric Pb(Zrl_x, Tix)O3 (PZT). In order to implement this comparative research, Co-based amorphous alloy (CoSiB), Fe-based nanocrystalline alloy (FeCuNbSiB) and Fe-based amorphous alloy (FeSiB) are used according to different magnetostriction (2s) and saturation magnetization (μtoMs) characteristics. The bending and longitudinal resonant ME voltage coefficients (αME,b and αME,1) are observed comparatively for CoSiB/Ni/PZT, FeCuNbSiB/Ni/PZT, and FeSiB/Ni/PZT composites. The experimental data indicate that the FeSiB/Ni/PZT composite has the largest remanent self-biased aME,b and aME,1 due to the largest magnetic grading of λs and μ0Ms in the FeSiB/Ni layer. When the number of FeSiB foils is four, the maximum remanent aME,b and aME,I at zero bias magnetic field are 57.8 V/cm·Oe and 107.6 V/cm·Oe, respectively. It is recommended that the high-permeability alloy is supposed to have larger λs and μ0Ms for obtaining a larger remanent self-biased ME responses in ME composite with high-permeability alloy.
基金the National Natural Science Foundation of China(Grant No.12047517)the International Cooperation Project of Science and Technology of Henan Province,China(Grant No.182102410096)+1 种基金the Natural Science Foundation of Henan Province,China(Grant No.202300410069)the China Postdoctoral Science Foundation(Grant Nos.2020M682274 and 2020TQ0089)。
文摘An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles calculations,we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets,which proves this idea in multiferroic heterostructures of ferromagnetic La TiO_(3)and ferroelectric Bi FeO_(3).The results show that the magnetic properties and two-dimensional electron gas concentrations of La TiO_(3)films can be controlled by changing the polarization directions of Bi FeO_(3).The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3 d electrons,which is the fundamental reason for the changing of magnetic properties.This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.