Converse Magnetoelectric Effect Research Articles

Performance optimization for magnetoelectric antennas based on a multi-field coupling analysis model

This paper presents a multi-field coupling model for magnetoelectric (ME) antennas, encompassing a ME film, electrode layers, and a substrate featuring a cavity structure. This model accounts for the nonlinear magnetoelastic coupling within the radiation layer and employs a combined DC and AC simulation methodology to capture the antenna's radiation mechanism. Leveraging this multi-field coupling model, performance differences between the ME antenna and an ideal ME composite film are analyzed. By exploring optimization schemes based on multi-physics fields, electrode materials, and structural design, the ME antenna's radiation performance is significantly enhanced. The findings demonstrate that the complete antenna structure, with its increased thickness and cavity design, exhibits a lower resonance frequency and a higher converse ME (CME) coefficient compared to the ideal ME film. The optimal CME effect is achieved under proper external stimuli, leading to a broader 3 dB bandwidth. Expanding the cavity dimensions enhances the CME coefficient by 42% and reduces the resonance frequency due to decreased acoustic wave loss. Adopting electrode materials with higher acoustic impedance elevates the CME coefficient, yet narrows the bandwidth. Conversely, using silver (Ag) electrodes promotes a broader bandwidth. Additionally, ME antenna arrays are designed to broaden the bandwidth by 300%.

Optimal polarization and susceptibility profiles of a half-filled open magnetoelectric Fermi-Hubbard optical dimer

Magnetoelectric materials, such as thin films and magnetoelectric antennae, exhibit tunable magnetic polarization using external electric field and electric polarization using external magnetic field at room temperature by introducing strain, for instance. A more straightforward method to optimize magnetoelectric effect is by adjusting the applied electromagnetic fields in systems modeled by the Fermi-Hubbard dimer. In this study, direct and converse magnetoelectric effects are theoretically observed in an open Fermi-Hubbard dimer by tuning the external electromagnetic fields. Results show that an external magnetic field can enhance the electric polarization and susceptibility of the dimer particles without the necessity of mechanical strain. Conversely, gradients in an external electric field modulate the magnetic polarization and susceptibility. This striking behavior in the Fermi-Hubbard dimer can serve as a physical model for developing quantum control of complex materials such as in biosensors, biomedical processes, and energy harvesting.

Preparation of BaTiO3/Y3Fe5O12 bilayers and their ferroelectric/magnetic properties

The converse magnetoelectric effect in the ferroelectric/ferrimagnetic bilayers shows a great promise for realizing energy efficient, dense, and fast information storage and processing. In this study, we prepare the hybrid structures consisting of a ferroelectric layer BaTiO3 (BTO) and a ferrimagnetic insulator layer Y3Fe5O12 (YIG) via magnetron sputtering technique and post-annealing procedure. A visible ferroelectricity hysteresis loop for the BTO film and an apparent magnetic hysteresis loop for the YIG film are obtained. Moreover, by capping a platinum layer on the hybrid structures and performing longitudinal spin Seebeck measurements, a detectable spin-charge conversion voltage is observed, and even significant manipulation of this conversion in BTO/YIG/Pt trilayers is achieved by electrical means. These results show great potential for the development of tunable YIG-based devices and are instructive for future artificial multiferroic heterostructures devices applications.

Electric field control of 180° magnetization reversal in a spin-valve multiferroic heterostructure

Electrical tuning of magnetism, rather than a spin current or magnetic field, has attracted much attention due to its great potential for designing energy-efficient spintronic devices. However, pure electric field (E-field) control of 180° magnetization reversal is still challenging. Thus, we report an E-field-controlled 180° magnetization reversal in a spin valve (SV)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) multiferroic heterostructure. Via the converse magnetoelectric coupling effect in CoFe/PMN-PT heterostructures, the magnetic anisotropy and coercive field of the CoFe film can be tremendously modulated by an E-field. We fabricated an optimized SV grown on the PMN-PT substrate, in which the magnetic moments of the free and pinned layers are parallel to each other at the initial state. By applying an E-field, the coercive field of the free layer was enhanced, exhibiting an antiparallel configuration between the free and pinned layers. Based on the theoretical and experimental results, a complete 180° magnetization reversal of the free layer can be obtained without a magnetic field. Accordingly, an E-field-controlled giant, reversible and repeatable magnetoresistance modulation can be achieved. This work proposes a feasible strategy to achieve E-field-controlled 180° magnetization reversal, which is critical for exploring ultralow power consumption magnetic memory devices.

Performance analysis of acoustically actuated magnetoelectric antennas via equivalent circuit method

Acoustically actuated magnetoelectric (ME) antennas based on resonant magnetoelectric coupling within ferromagnetic/piezoelectric ME laminated composites have recently been considered as a promising solution for antenna miniaturization. However, its radiation performance has been theoretically overestimated, since the negative effects on performances due to the magnetization saturation and the nonlinear mechanical behavior that occur from high-field driving have not been paid enough attention. This work presents a unique equivalent-circuit-based numerical method to analyze the near-field resonance radiation performances of ME antennas driven by high electric fields. In this method, we establish an equivalent circuit of the converse magnetoelectric effect for a ME laminated composite to describe the operating principle of acoustically actuated electromagnetic radiation. The equivalent parameters related to resonance characteristics are determined by fitting the circuit model to the data from frequency response measurements of the near-field magnetic flux density. The validity of the model is verified by comparing the theoretical predictions with the experimental results, in the view of the volume fraction dependence of the mechanical resonance-related radiation characteristics of the fabricated ME composites. Based on the proposed model, the influence of driving voltage amplitude on near-field radiation performances is further analyzed by experimental fitting to the model, and the potential limiting factors of ME antennas are discussed according to the driving-amplitude dependence of parameters obtained from the fit. This work provides an effective and engineering-friendly approach to predict the evolution of ME antenna performances, leading a way to improve the performance limit for resonant magnetoelectric coupling.

Self-Biased Magneto-Electric Antenna for Very-Low-Frequency Communications: Exploiting Magnetization Grading and Asymmetric Structure-Induced Resonance.

VLF magneto-electric (ME) antennas have gained attention for their compact size and high radiation efficiency in lossy conductive environments. However, the need for a large DC magnetic field bias presents challenges for miniaturization, limiting portability. This study introduces a self-biased ME antenna with an asymmetric design using two magneto materials, inducing a magnetization grading effect that reduces the resonant frequency during bending. Operating principles are explored, and performance parameters, including the radiation mechanism, intensity and driving power, are experimentally assessed. Leveraging its excellent direct and converse magneto-electric effect, the antenna proves adept at serving as both a transmitter and a receiver. The results indicate that, at 2.09 mW and a frequency of 24.47 kHz, the antenna has the potential to achieve a 2.44 pT magnetic flux density at a 3 m distance. A custom modulation-demodulation circuit is employed, applying 2ASK and 2PSK to validate communication capability at baseband signals of 10 Hz and 100 Hz. This approach offers a practical strategy for the lightweight and compact design of VLF communication systems.

Modeling the Converse Magnetoelectric Effect in the Low-Frequency Range.

This article is devoted to the theory of the converse magnetoelectric (CME) effect for the longitudinal, bending, longitudinal-shear, and torsional resonance modes and its quasi-static regime. In contrast to the direct ME effect (DME), these issues have not been studied in sufficient detail in the literature. However, in a number of cases, in particular in the study of low-frequency ME antennas, the results obtained are of interest. Detailed calculations with examples were carried out for the longitudinal mode on the symmetric and asymmetric structures based on Metglas/PZT (LN); the bending mode was considered for the asymmetric free structure and structure with rigidly fixed left-end Metglas/PZT (LN); the longitudinal-shear and torsional modes were investigated for the symmetric and asymmetric free structures based on Metglas/GaAs. For the identification of the torsion mode, it was suggested to perform an experiment on the ME structure based on Metglas/bimorphic LN. All calculation results are presented in the form of graphs for the CME coefficients.

Magnetic-Field-Assisted Electric-Field-Induced Domain Switching of a Magnetic Single Domain in a Multiferroic/Magnetoelectric Ni Nanochevron/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-PT) Layered Structure.

We report the magnetic-field-assisted electric-field-controlled domain switching of a magnetic single domain in a multiferroic/magnetoelectric Ni nanochevrons/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-PT) layered structure. Initially, a magnetic field was applied in the transverse direction across single-domain Ni nanochevrons to transform each of them into a two-domain state. Subsequently, an electric field was applied to the layered structure, exerting the converse magnetoelectric effect to transform/release the two-domain Ni nanochevrons into one of two possible single-domain states. Finally, the experimental results showed that approximately 50% of the single-domain Ni nanochevrons were switched permanently after applying our approach (i.e., the magnetization direction was permanently rotated by 180 degrees). These results mark important advancements for future nanoelectromagnetic systems.

Metastable Co3Mn/Fe/Pb(Mg1/3Nb2/3)O3–PbTiO3 multiferroic heterostructures

Using a molecular beam epitaxy technique, we experimentally demonstrate a multiferroic heterostructure consisting of metastable ferromagnetic Co3Mn on piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT). Inserting a 2-nm-thick Fe layer between Co3Mn and PMN-PT(001) allows the formation of bcc Co3Mn layers even at an extremely low growth temperature of ∼80°C. Upon increasing this temperature to 200 °C, a bcc Co3Mn/Fe/PMN-PT(001) multiferroic heterostructure with a relatively large saturation magnetization of ∼1680 kA/m and an atomically flat interface is obtained, resulting in an obvious converse magnetoelectric (CME) effect. The large CME effect originates mainly from the strain-induced modulation of the magnetic anisotropy energy, supported by the first-principles calculations.

Lattice‐mediated room temperature magnetoelectric effect in (1‐y)BiFe1‐xCrxO3‐yBaTi1‐xMnxO3 solid solutions

AbstractElectric field (E) control of magnetism is a persistent challenge in low‐power consumption spintronic devices. A promising way to realize this control is to use the converse magnetoelectric (ME) effect in insulating multiferroics. Here, we report considerable and repeatable E‐modulated magnetization (M) at room temperature and even at 350 K via the significantly enhanced converse ME effect near the morphotropic phase boundary (MPB) of the Cr‐Mn co‐doped (1‐y)BiFe1‐xCrxO3‐yBaTi1‐xMnxO3 (0.15 ≤ y ≤ 0.33, 0 ≤ x ≤ 0.03) solid solutions. In situ X‐ray diffraction and Raman scattering experiments at different applied E for the sample near the MPB (i.e., y = 0.27, x = 0.03) show E‐induced shift, broadening, and splitting in the {002}PC reflection, as well as a nearly monotonous variation in intensity of several phonon modes with E, reminiscent of the E‐dependent M behavior. These results indicate that both E‐induced lattice distortion and phase transformation dominate the converse ME effects in these samples. Our demonstration of the E‐regulation of magnetism via the E‐sensitive crystal structures in designed insulating multiferroics near MPB may suggest a potential route to obtain efficient low‐power spintronic devices.

Control of magnetism at low electric fields in multiferroic 0.58BiFeO3–0.42Bi0.5K0.5TiO3 single crystal near morphotropic phase boundary

Electric field (E) control of magnetism (M) via the converse magnetoelectric (ME) effect in insulating multiferroics is promising in energy-efficient spintronic devices. However, strong ME coupling together with relatively low electric fields for E control of M is still challenging in practical applications. Here we report considerable and reproducible E control of M with E even much lower than the ferroelectric (FE) coercive field (EC) at room temperature (RT) in the multiferroic 0.58BiFeO3–0.42Bi0.5K0.5TiO3 (BF-BKT) single crystals residing in the tetragonal region, but next to the morphotropic phase boundary (MPB). The E controlled M can be substantially suppressed by high magnetic fields (H). It is revealed that the E controlled M can be rather ascribed to both the E-induced lattice distortion and phase transformation than to FE domain switching in BF-BKT. The weakened converse ME effect at high H is attributed to the H-induced suppression of phase transformation. Our results demonstrate that the converse ME effect mediated by E-sensitive lattice structures in multiferroics near MPB might be promising in achieving ultralow power spintronic devices.

Магнитоимпеданс в планарной магнитоэлектрической гетероструктуре аморфный ферромагнетик-пьезоэлектрик: модуляция электрическим полем

The magnetoimpedance effect and the converse magnetoelectric effect in a planar heterostructure consisting of mechanically bonded layers of amorphous ferromagnet FeBSiC and piezoelectric lead zirconate titanate are studied. Magnetoimpedance was observed in the frequency range of 0.1-40 MHz and bias dc magnetic field of 0-300 Oe; the maximum magnitude of the effect at a frequency of 10 MHz reached 12%. The converse magnetoelectric effect was observed in magnetic fields of 0-50 Oe; the maximum value of the effect at the structure acoustic resonance frequency of 40 kHz was 1.45 G/(V/cm). Amplitude modulation of the magnetoimpedance by an electric field at the resonance frequency of the structure with a coefficient of ~1∙10─2 is found. Modulation occurs as a result of a combination of the piezoelectricity and magnetostriction of the layers, which leads to a change in the transverse magnetic permeability and the thickness of the skin-layer of the ferromagnet.

A two-dimensional multi-field coupling model for converse magnetoelectric effect in acoustically actuated antennas

The radiation performance of acoustically actuated magnetoelectric (ME) antennas is originated from converse magnetoelectric (CME) effect that converts the electric field to magnetic field due to strain coupling. This paper presents a two-dimensional model for the CME effect of ME antennas with considering a fully magneto-elastic coupled characteristic of magnetostrictive materials. The nonlinear magnetostrictive relation is equivalent to a linear-like form using the equivalent parameter method. The coupled effects of magnetic bias and pre-stress on the CME coupling are discussed. The prediction for the CME coefficient shows a good agreement with the experimental data. The results indicate that pre-stress and magnetic bias have a strong-coupled effect on the CME effect. In addition, optimal loading modes are obtained for improving the CME effect. The radiations of ME antennas have not yet been obtained. Nevertheless, the results in this work may provide a basis for further investigation on the radiations.

Converse magnetoelectric coupling coefficient greater than [formula omitted] s/m in perpendicularly magnetized Co/Pd multilayers on Pb(Mg[formula omitted]Nb[formula omitted])O3-PbTiO3

Multiferroic heterostructures consisting of Co/Pd multilayers on Pb(Mg1/3Nb2/3)O3-PbTiO3(011) substrates are experimentally investigated. The converse magnetoelectric (CME) effect is characterized by anomalous Hall effect measurements with application of an electric field (E). The remanent magnetization state for the [Co(0.8 nm)/Pd(2 nm)] multilayer is significantly modulated by the application of E. The room-temperature CME coupling coefficient (αE) is estimated to be 1.0–1.1 × 10−6 s/m, which is the largest among those of multiferroic heterostructures with perpendicular magnetic anisotropy.

Low-frequency resonant magnetoelectric effects in a planar heterostructure of ferromagnetic yttrium iron garnet film and piezoelectric quartz

Low-frequency resonant magnetoelectric (ME) effects in a planar heterostructure containing a 50 μm thick single-crystal film of yttrium iron garnet (YIG) and a crystalline quartz platelet were studied. The ME effects in the mechanically coupled composite arise due to a combination of magnetostriction of the YIG film and the piezoelectric effect in quartz. The effects manifest as mutual transformation of ac magnetic and electric fields. When the layered composite was excited by an ac magnetic field (direct ME effect) at a planar acoustic resonance frequency of 128 kHz, the ME field conversion coefficient was 8.8 V/(Oe∙cm). When excited by an ac electric field (converse effect), the ME conversion coefficient was 0.32 G/(V/cm). Nonlinear ME effects caused by the nonlinear magnetostriction of the YIG film were observed as frequency doubling upon excitation of the direct ME effect by a magnetic field at a frequency equal to half the resonant frequency, as well as at the converse ME effect upon excitation by an electric field at the frequency of the resonance of the structure. In spite of weak magnetostriction for YIG, the resonant ME effects in the YIG-quartz composite are comparable in magnitude to the effects in composites with high magnetostriction materials, show high quality factor of Q ∼ 2200 and are observed in weak magnetic fields H ∼ 0–60 Oe. These results demonstrate the potential for YIG film-quartz composites application in electronic devices.

Enhanced electric field control of magnetism in ternary BiFeO3-based ceramics

We report an unambiguous observation of a room temperature (RT) converse magnetoelectric effect (CME) in ternary BiFeO3-based systems near a morphotropic phase boundary (MPB). The results of in situ XRD diffraction at different applied electric fields reveal that the lattice distortion and phase transitions dominate the RT CME in the samples near the MPB. Our results provide an experimental proof and an explanation for the electric-field control of the magnetism effect obtained at the MPB, which may provide an effective way to design multiferroics for potential applications in magnetoelectric devices with low power consumption.

Display of converse and direct magnetoelectric effect in double perovskite LaYFe2O6

This work reports the simultaneous observation of converse magnetoelectric (CME) and direct magnetoelectric (DME) effects in LaYFe2O6. The structural, magnetic, and magnetoelectric properties of LaYFe2O6, prepared by the sol-gel auto-combustion method and sintered at various temperatures, have been studied. The x-ray powder diffraction study suggests the double perovskite structure with symmetries P21nm (∼90%) and Pbnm (∼10%). The alternate ordering of La and Y ions is confirmed by the neutron powder diffraction (ND) study, which also suggests the antiferromagnetic (AFM) ordering of spins. AFM behavior is also manifested by the magnetic field-dependent magnetization (M) measurement. A higher P21nm phase content is desirable in the context of magnetoelectricity. Magnetic transition (∼700 K) is asserted in the temperature-dependent M measurement. The isothermal magnetization study shows weak ferromagnetism probably due to gradually increasing spin canting with temperature until the transition temperature. The highest CME coefficient (∼2.26 mOe cm/V) as well as DME coefficient (∼0.45 mV/cm Oe) in this material are recorded. True magnetoelectricity for temperature as high as 400 K opens up a new avenue on the playground of magnetoelectric (ME)-based applications.

Near-field coupling and wireless signal transmission using a magnetoelectric laminated composite antenna

Magnetoelectric (ME) antennas utilize the direct or converse ME effects at acoustic resonance to receive or transmit electromagnetic (EM) signals, making ultra-compact antennas feasible. This work presents a miniaturized ME antenna working at very low frequency (VLF) band. A piezoelectric wafer and magnetostrictive foils are bonded together to form the 12×2.1×0.08 cm3 ME antenna. The near-field coupling between the ME antenna and magnetic rod coil has been measured to verify the reciprocity. The proposed entire circuit simulation models agree well with the experimental results, explaining the maximum power gap and frequency offset phenomenon. In addition, both practical and simulation results confirm that near-field coupling depends on mutual inductance rather than EM radiation. Based on the emulation of circuits, L-section impedance matching networks are introduced to improve the original power transmission coefficient by 21 dB. The ME antenna is lightweight, wide-band, and easy to match compared with a conventional coil.

Numerical simulation investigation of direct and converse magnetoelectric effects in laminated composites with longitudinally magnetization and polarization

Numerical simulation is often used for piezoelectric materials or magnetostrictive materials, but it is rarely used for magnetoelectric materials due to the coupling complexity. COMSOL multiphysics is a powerful and effective numerical simulation software package. It can not only study the influence of parameter and frequency changes, but also extract stress distribution, electric potential, vibration mode, etc. In this paper, based on the existing equivalent circuit theory of L-L mode magnetoelectric laminates, COMSOL software is used to analyze the changes of DME and CME coefficients with frequency, the frequency curves of different proportions of magnetostrictive materials, and the vibration modes at the frequency peaks. It is obvious that the L-L mode laminated composite vibrates along the length direction regardless of DME and CME effects. The numerical simulation results are in good agreement with the existing theoretical analysis and experimental research. The results show that this simulation method is desirable and lays a foundation for further nonlinear theoretical analysis.

Magnetoelectric effects in a composite ferromagnet–piezoelectric heterostructure under pulsed excitation

Magnetoelectric (ME) effects in multiferroic ferromagnet–piezoelectric (PE) composite heterostructures result in a change in the electric polarization under the action of magnetic field or a change in the magnetization under the action of electric field and, therefore, are interesting from scientific point of view and for applications. In this work, the direct and converse ME effects are experimentally studied when a planar amorphous ferromagnet–PE lead zirconate–titanate structure is excited by magnetic and electrical field pulses with duration from microseconds to tens of milliseconds. Under the action of magnetic field pulses, the structure generates damped voltage oscillations with a frequency equal to the acoustic resonance frequency of the structure, as well as an exponentially decreasing dc voltage. By choosing the duration of magnetic pulses, it is possible selectively excite the linear ME effect in the structure or generate the second voltage harmonic at the resonance frequency. Electrical field pulses result in the excitation of damped magnetization oscillations at the resonance frequency of the heterostructure. The pulsed excitation method allows to estimate the ME conversion coefficients for both the direct and converse ME effects.