Transverse Magnetoelectric Voltage Research Articles

Study of enhanced magnetoelectric coupling behavior in asymmetrical bilayered multiferroic heterostructure with two resonance modes

The resonant enhancement of the magnetoelectric coupling effect due to the bending and length modes had been investigated in the asymmetrical bilayered heterostructure consisting of the La0.7Sr0.3MnO3 and BaTiO3 deposited on SrTiO3. The frequency-dependent transverse magnetoelectric voltage coefficient demonstrated two sharp peaks in the vicinity of electromechanical resonant frequencies, which were attributed to the bending and length vibration modes, respectively. The value of the magnetoelectric voltage coefficients for the first peak was higher than that of the second one, which ascribed to the phase shift between the excited magnetic field and induced dielectric polarization. This result demonstrated the asymmetrical bilayered heterostructure has dramatically enhanced magnetoelectric effect when operated near these frequencies, which is likely to provide a tremendous opportunity for configuring the corresponding devices.

The effect of thickness-dependent strain relaxation on magnetoelectric behaviors for highly c-axis oriented BiFeO3 films on Si substrate

The thickness-dependent strain-relaxation behavior and the associated impacts upon the magnetic, electric properties and magnetoelectric coupling effect for the highly c-axis oriented BiFeO3 (BFO) film films grown on (001) oriented Si substrate were studied. The result shown that the value of remnant polarization and coercive field were suppressed as the strain relaxes with increasing thickness. The BFO films also presented typical weak ferromagnetic hysteresis loops with a low coercive field and small remnant magnetization, and the saturated magnetization and remnant magnetization decreasing with increasing film thickness. The room temperature dynamic magnetoelectric coupling was approved by the transverse magnetoelectric voltage coefficients, which also decreased with strain relaxation due to the increase of thickness, and the maximum was around 265 mV/cm.Oe when the film thickness is 50 nm.

Elastic and Anelastic Properties of a Particulate Magnetoelectric Composite (x)Mn0.4Zn0.6Fe2O4–(1 − x)PbZr0.53Ti0.47O3

Elastic (elastic compliance) and anelastic (internal friction) properties of a particulate magnetoelectric composite (x)Mn0.4Zn0.6Fe2O4–(1 − x)PbZr0.53Ti0.47O3 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.6) at a frequency of ≈30 Hz over a temperature range from 290 to 700 K are studied. Temperature dependences of elastic compliance and internal friction near the ferroelastic Curie point are found to be well approximated by power functions. Observed dependences of exponents on the composite composition are associated with the substitution of atoms in the PbZr0.53Ti0.47O3 lattice by atoms in the Mn0.4Zn0.6Fe2O4 lattice during the high‐temperature sintering of composite samples. A correlation is revealed between the transverse magnetoelectric voltage coefficient and smearing parameters of the ferroelastic phase transition.

Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor.

This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb0.3Dy0.7Fe1.92)/PZT (Pb(Zr,Ti)O3) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor kc, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing kc for the transverse ME voltage coefficient αv and the optimum thickness ratio noptim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor kc, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured αv and the DC bias magnetic field Hbias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for kc = 0.11 and 0.56 for kc = 0.08. Both the theoretical ME voltage coefficient αv and optimum thickness ratio noptim containing kc agreed well with the measured data, verifying the reasonability and correctness for the introduction of kc in the modified equivalent circuit model.

Theoretical prediction of resonant and off-resonant magnetoelectric coupling in layered composites with anisotropic piezoelectric properties

In order to explain unique magnetoelectric (ME) coupling behaviors found in a trilayer ME laminate having a piezoelectric crystal particularly with anisotropic planar piezoelectric properties, a theoretical model based on the average field method is developed. New analytical expressions could be derived to predict the transverse ME voltage coefficients at off- and in-resonance frequencies respectively. It is predicted that transverse ME voltage coefficients should be anisotropic under in-plane magnetic fields at both off- and in-resonance frequencies. Furthermore, numerical simulations based on material parameters of a representative 2-2 trilayer, composed of Metglas/[011] Pb(Mg1/3Nb2/3)O3–PbTiO3 crystal/Metglas, prove the emergence of multiple resonance frequencies and characteristic phase difference in the complex ME voltages at each resonant frequency. All these theoretical predictions are in good agreement with the experimental results both at off- and in-resonant frequencies. The theoretical expressions developed here could be broadly applicable to the various types of layered ME laminates with a piezoelectric material with or without anisotropic piezoelectric coefficients.

Magnetoelectric Coupling in Metglas/BaTiO<sub>3</sub>/Metglas Lead-Free Magnetoelectric Composites

We report the magnetoelectric (ME) coupling in ME composites composed of NiFe2O4 (NFO) or metglas as magnetostrictive phases and BaTiO3 (BTO) as piezoelectric phase, targeting lead free magetnic field sensors. NFO and BTO phases were synthesized by solid state sintering method and further characterized by using XRD and FESEM techniques. The P-E hysteresis curve shows good ferroelectric behavior with saturation polarization of Ps = 15.87 C/cm2 and coercive electric field of 130 kV/cm. The ME response was characterized as a function of dc magnetic field at a fixed frequency. The transverse ME voltage coefficient, αME31 shows 2 times larger magnitude than that of longitudinal ME voltage coefficient, αME31. The maximum αME31 of 37 mV/cm•Oe (@Hdc = 250 Oe) is observed for NFO/BTO/NFO ME composites with thickness ratio of tm/tp = 1.0. The ME coupling is further enhanced by replacing NFO layers by highly magnetostrictive metglas layers. Metglas/BTO/metglas laminates show large αME31 value of 81 mV/cm•Oe at relatively lower Hdc of 145 Oe. The present laminates can offer promising opportunities of engineering environmental friendly ME laminate for applications in ME devices such as energy harvester and magnetic field sensors.

Transverse Magnetoelectric Effect in Nickel Zinc Ferrite-Lead Zirconate Titanate Layered Composites

By using a elastic mechanics model the transverse magnetoelectric voltage coefficient of magnetostrictive-piezoelectric bilayer is derived according to the constitutive equations. The transverse magnetoelectric coupling of nickel zinc ferrite-lead zirconate titanate (Ni0.8Zn0.2Fe2O4–Pb (Zr,Ti)O3, NZFO-PZT) layered composites were calculated by using the corresponding material parameters of individual phases. NZFO samples have been synthesized with sol–gel technique. Layered composites NZFO-PZT and NZFO-PZT-NZFO have been fabricated by binding discs of NZFO and commercially available PZT, and the transverse magnetoelectric effect have been investigated. The peak value of transverse magnetoelectric voltage coefficient for NZFO-PZT-NZFO trilayer reaches 252.4 mV/cmOe under a bias magnetic field of about 320 Oe, which is about three times as large as that of NZFO-PZT bilayer. The interface coupling parameter of trilayer is significantly higher than that of bilayer.

Dielectric and magnetoelectric properties of co-fired PbZr0.52Ti0.48O3–Co0.6Zn0.4Mn0.3Fe1.7O4–PbZr0.52Ti0.48O3 trilayer composites

In this paper we report the dielectric and magnetoelectric (ME) properties of co-fired Pb0.52Ti0.48O3–Co0.6Zn0.4Mn0.3Fe1.7O4–PbZr0.52Ti0.48O3 (PZT–CZFMO–PZT) trilayer composites prepared using Mn and Zn simultaneously substituted CoFe2O4 (Co0.6Zn0.4Mn0.3Fe1.7O4) as a magnetostrictive phase. For PZT–CZFMO–PZT composites, the maximum values of longitudinal and transverse ME voltage coefficient (αE33 and αE31) were observed to be comparable in magnitude contrary to the usual trend (αE31 much greater than αE33) for ME composite structures. The highest transverse ME voltage coefficient αE31 ~64 mV/cm Oe (at an applied ac magnetic field of frequency ~1 kHz) was obtained for the composite containing the thickest layer of CZFMO. The dielectric constant spectra for PZT–CZFMO–PZT composites demonstrated very high values of resonance frequency (~47–81 MHz) and band width (~9–13 MHz).

Enhanced magnetoelectric effect in magnetostrictive/piezoelectric laminates through adopting magnetic warm compaction Terfenol-D

In this paper, bi-layered magnetoelectric (ME) composites laminated with the bonded Tb1−xDyxFe2−y (Terfenol-D) prepared by means of magnetic warm compaction and (Pb(Zr0.52Ti0.48)O3 (PZT-5H) ceramics were developed. The results show that the transverse ME voltage coefficient of ME composite is about 6 V/cm Oe, 3 times of that prepared by traditional room temperature pressure molding, implying that the magnetic warm compaction technology is an promising way to prepare the bonded Terfenol-D laminated ME composites. Additionally, the enhanced ME voltage coefficient is related to the preferred orientation of the Terfenol-D, and the magnetic field is key factor in the magnetic warm compaction technology.

Features of the direct magnetoelectric effect in two-layer Tb0.12Dy0.2Fe0.68-PbZr0.53Ti0.47O3 composites

The transverse magnetoelectric effect in two-layer Tb0.12Dy0.2Fe0.68-PbZr0.53Ti0.47O3 composites with Tb0.12Dy0.2Fe0.68 ferromagnetic layers of various thicknesses are studied over the temperature range of 77 to 423 K at resonant frequencies of the bending oscillations. It is established that for all of the studied composites, the transverse magnetoelectric voltage constant passes at 253 K through a peak whose nature is associated with features of the magnetic constituent of the composites.

Enhancement of resonant and non-resonant magnetoelectric coupling in multiferroic laminates with anisotropic piezoelectric properties

Giant transverse magnetoelectric voltage coefficients |α̃E| = 751 and 305 V/cmOe at two electromechanical antiresonance frequencies are found in the symmetric metglas/[011]-oriented 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 crystal/metglas laminate. Unique torsional and diagonal vibration modes are identified to be responsible for those giant |α̃E| values. Moreover, α̃E is found to be anisotropic depending on the in-plane magnetic field directions, making the piezoelectrics with anisotropic planar piezoelectricity potentially useful base materials for multi-frequency, phase-sensitive magnetoelectric devices.

Magneto electric effects in BaTiO3–CoFe2O4 bulk composites

Influence of a static magnetic field (HDC) on the hysteresis and remanence in the longitudinal and transverse magneto electric voltage coefficients (MEVC) observed in [BaTiO3]1−x–[CoFe2O4]x bulk composites are analyzed. Remanence in MEVC at zero bias (HDC=0) is stronger in the transverse configuration over the longitudinal case. The observed hysteretic behavior in MEVC vs. HDC is correlated with the changes observed in the magnetostriction characteristics (λ and dλ/dH) reported for [BaTiO3]1−x–[CoFe2O4]x bulk composites.

Giant magnetoelectric effects in multilayered composites of cobalt ferrite and lead magnesium niobate titanate

The magnetoelectric (ME) coupling responses of [CoFe2O4/(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3]n, represented as (CFO/PMNT)n, multilayered composites were theoretically investigated by using an average method. It is found that a stronger interface coupling could be obtained in multilayers than in bilayers if the number of layers (n) is reasonably increased. Using an empirical dependence of the interface coupling parameter on the number of layers n, it is theoretically estimated that the ME coupling effect is first enhanced and then deteriorated with the gradual increase in n. The best ME response is estimated to occur at n=15, where the transverse ME voltage coefficient αE,31 reaches as high as 658 mV·cm−1·Oe−1. Moreover, it is theoretically found that the ME coupling effect in (CFO/PMNT)n multilayered composites is strongly dependent on the volume fraction of the piezoelectric (or magnetostrictive) phase, and the ME voltage coefficient for transverse field orientation (αE,31) is estimated to be roughly 90% higher than that for the longitudinal case (αE,33), revealing a large anisotropy in the ME coupling effect of (CFO/PMNT)n multilayered composites. These findings pave the way for experimental achievement of strong ME coupling responses, and provide important implications for the design and performance optimization of related devices comprising this kind of multiferroic magnetoelectric materials.

Bath temperature effect on magnetoelectric performance of Ni–lead zirconate titanate–Ni laminated composites synthesized by electroless deposition

Magnetoelectric (ME) Ni–lead zirconate titanate–Ni laminated composites have been prepared by electroless deposition at various bath temperatures. The structure of the Ni layers deposited at various bath temperatures was characterized by X-ray diffraction, and microstructures were investigated by transmission electron microscopy. The magnetostrictive coefficients were measured by means of a resistance strain gauge. The transverse ME voltage coefficient α E,31 was measured with the magnetic field applied parallel to the sample plane. The deposition rate of Ni increases with bath temperature. Ni layer with smaller grain size is obtained at higher bath temperature and shows higher piezomagnetic coefficient, promoting the ME effect of corresponding laminated composites. It is advantageous to increase the bath temperature, while trying to avoid the breaking of bath constituents.

Magnetic and Magnetoelectric Properties of Particulate (x)PbZr0.53Ti0.47O3–(1−x) Mn0.4Zn0.6Fe2O4 Composites

Magnetic and magnetoelectric properties of particulate (x)PbZr0.53Ti0.47O3–(1−x) Mn0.4Zn0.6Fe2O4 composites, where x is 0; 0.2; 0.4; 0.6; 0.8; and 1.0, have been studied. Measurements of magnetization—magnetic field loops, temperature and field dependences of the differential magnetic susceptibility as well as the transverse magnetoelectric voltage coefficient have shown the profound effect of the composite composition on studied properties.

Magnetoelectrical effect in layered composites PbZr0.53Ti0.47O3-Mn0.4Zn0.6Fe2O4

The magnetoelectric (ME) effect in two- and three-layered composites made up of polarized ceramic plates of lead zirconate-titanate PbZr0.53Ti0.47O3 (PZT) and manganese-zinc ferrite Mn0.4Zn0.6Fe2O4 (MZF) has been studied. Dependences of the transverse ME voltage coefficient (α31) on the magnetostrictive layer thickness and the magnetic field intensity and frequency have been established. The mechanical coupling coefficient of the composite plates has been estimated. Results obtained for two-layered PZT-MZF structures have been analyzed using the method of efficient medium parameters.

Theory of magnetoelectric effect for bending modes in magnetostrictive-piezoelectric bilayers

In a magnetostrictive-piezoelectric bilayer the interaction between the magnetic and electric subsystems occurs through mechanical deformation. A model is discussed here for the resonance enhancement of such magnetoelectric (ME) interactions at frequencies corresponding to bending oscillations. The thickness dependence of stress, strain, and magnetic and electric fields within a sample are taken into account so that the bending deformations could be considered in an applied magnetic or electric field. The frequency dependence for longitudinal and transverse ME voltage coefficients have obtained by solving electrostatic, magnetostatic, and elastodynamic equations. We consider boundary conditions corresponding to bilayers that are free to vibrate at both ends, or simply supported at both ends, or fixed at one end. It is shown that the bending resonance and consequent enhancement in ME coupling occurs at the lowest frequency for a bilayer that is fixed at one end and free at the other end. The model is applied to a specific case of permendur-lead zinconate titanate bilayer. The theory is in very good agreement with representative data.

Magnetoelectric effect in laminate composites of Tb1−xDyxFe2−y and Cr doped BaTiO3

Cr doped BaTiO3 has been synthesised with sol–gel technique. Its transformation point of ferroelectric to paraelectric and the latent heat of the transformation were observed respectively. They are a little less than those for pure BaTiO3. Bonded layered composites Tb1−xDyxFe2−y–BaTi0·99Cr0·01O3 have been fabricated. Their magnetoelectric (ME) effects have been investigated. The transverse ME voltage coefficients for the bilayer Tb1−xDyxFe2−y–BaTi0·99Cr0·01O3 and the trilayer Tb1−xDyxFe2−y–BaTi0·99Cr0·01O3–Tb1−xDyxFe2−y can reach 732·5 and 2753 mV Oe−1 cm−1 respectively, under a bias magnetic field 355 Oe at room temperature. These are about 54 and 56% larger than those for the bilayer and trilayer composed by pure BaTiO3 respectively. This suggests that the doped BaTiO3 can be a new choice of piezoelectrics to compose ME composites.

Influence of iron doping level upon magnetoelectric coupling in BaTi1-zFezO3+δ-Tb1-xDyxFe2-y bilayer composites

Perovskites BaTi1-zFezO3+δ with doping level from 0.005 to 0.02 have been synthesized with sol-gol method. The X-ray diffraction shows that the doped perovskites retain the original tetragonal structure. Defferential thermal analysis demonstrates that both the transformation temperature of ferroelectric to paraelectric and the latent heat of the transformation decrease with increasing doping level. Bilayer composites BaTi1-zFezO3+δ-Tb1-xDyxFe2-y bilayer composites havebeen fabricated after the piezoelectrics being poled and their magnetoelectric effect has been investigated using a bias magnetic field and an ac magnetic field of 100Hz. The experimental result shows that the transverse magnetoelectric voltage coefficient of the bilayer composites can reach a maximum at doping level of 1.5%. The value of the maximum is 1788mV/A under a bias magnetic field of 60kA/m at room temperature. The analysis of magnetoelectric spectroscopy also shows a higher resonance peak and a higher resonance frequency for the sample containing BaTi0.985Fe0.015O3+δ， suggesting a higher piezoelectric coefficient in the doped BaTiO3 and some difference in interfacial coupling coefficients in the bilayer composites containing the doped samples， respectively.

Is the magnetoelectric coupling in stickup bilayers linear?

The magnetoelectric (ME) characterization of stickup bilayers Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3 and trilayers of Ni0.8Zn0.2Fe2O3-Pb(Zr, Ti)O3-Ni0.8Zn0.2Fe2O3 are discussed. The ME interactions in the trilayers were found much stronger than that of bilayers prepared with the same technique. The maximum transverse ME voltage coefficient of trilayer can reach 430 (mV/cm Oe) under a magnetic field H=215 Oe. This value is much closer to the theoretical estimate for the ME coupling for bilayers. The frequency dependence of αE also reveals the difference of the elastic and magnetoelectric coupling between the bilayers and trilayers. Analysis suggests that a more approach linear response of the pezioelectric layer to the magnetostriction of the ferrite may be responsible for the significant enhanced ME effect in the trilayers.