Magnetoelectric Behavior Research Articles

Unravelling the nature of magneto-electric coupling in room temperature multiferroic particulate (PbFe0.5Nb0.5O3)\u2013(Co0.6Zn0.4Fe1.7Mn0.3O4) composites

Multiferroic composites are promising candidates for magnetic field sensors, next-generation low power memory and spintronic devices, as they exhibit much higher magnetoelectric (ME) coupling and coupled ordering parameters compared to the single-phase multiferroics. Hence, the 3-0 type particulate multiferroic composites having general formula (1 − Φ)[PbFe0.5Nb0.5O3]-Φ[Co0.6Zn0.4Fe1.7Mn0.3O4] (Φ = 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, (1 − Φ) PFN-ΦCZFMO) were prepared using a hybrid synthesis technique. Preliminary structural and microstructural analysis were carried out using XRD and FESEM techniques, which suggest the formation of 3-0 type particulate composite without the presence of any impurity phases. The multiferroic behaviour of the composites is studied with polarization versus electric field (P-E) and magnetization versus magnetic field (M-H) characteristics at room temperature. The nature of ME coupling was investigated elaborately by employing the Landau free energy equation along with the magneto-capacitance measurement. This investigation suggests the existence of biquadratic nature of ME coupling (P2M2). The magneto-electric coupling measurement also suggests that strain mediated domain coupling between the ferroelectric and magnetic ordering is responsible for the magneto-electric behaviour. The obtained value of direct ME coefficient 26.78 mV/cm-Oe for Φ = 0.3, found to be higher than the well-known single-phase materials and polycrystalline composites.

Metamagnetic transitions and magnetoelectricity in the spin-1 honeycomb antiferromagnet Ni2Mo3O8

Earlier neutron scattering studies suggested the coexistence of complex stripelike and zigzaglike antiferromagnetic orders in polar honeycomb lattice ${\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$, while its magnetoelectric (ME) behavior as an emergent effect is thus of high interest. Here we report our observations of two metamagnetic transitions and novel ME responses of ${\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ single crystals against high magnetic field $H$ up to \ensuremath{\sim}60 T. The $c$-axis (polar axis) spontaneous electric polarization ${P}_{\mathrm{spin}}$, emerging at the magnetic N\'eel temperature ${T}_{N}\ensuremath{\sim}5.5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, and its remarkable response to $H$ applied along the $c$ axis ($H//c$) and $a$ axis ($H//a$), respectively, provide the clear evidence for the magnetism-driven ferroelectricity. While the magnetism exhibits the in-plane anisotropy to some extent, the magnetic field dependencies of magnetization and electric polarization in the low-field region and high-field region are distinctly different. In the low-field region where a weak spin-flop type metamagnetic transition occurs, the electric polarization response shows the parabolic dependence of magnetic field applied along both the $c$ axis and in-plane $a$ axis. The second metamagnetic transition happens when the magnetic field extends up to the high-field region where the magnetization and electric polarization response at low temperature are characterized by an extraordinarily broad plateau for the magnetic field along the $c$ axis but roughly linear dependence for field along the $a$ axis. These unusual phenomena are discussed, based on the symmetry-related local ME tensor analysis, and it is suggested that both the spin current and p-d hybridization mechanisms may contribute to the spontaneous electric polarization and ME responses. The present work demonstrates ${\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ as a unique multiferroic and promising platform for exploring the rich spin-1 physics and ME phenomena in honeycomb lattice.

Tuning the tilting of the spiral plane by Mn doping in YBaCuFeO5 multiferroic

The layered perovskite YBaCuFeO5 (YBCFO) is considered one of the best candidates to high-temperature chiral multiferroics with strong magnetoelectric coupling. In RBaCuFeO5 perovskites (R: rare-earth or Y) A-site cations are fully ordered whereas their magnetic properties strongly depend on the preparation process. They exhibit partial cationic disorder at the B-site that generates a magnetic spiral stabilized through directionally assisted long range coupling between canted locally frustrated spins. Moreover the orientation of its magnetic spiral can be critical for the magnetoelectric response of this chiral magnetic oxide. We have synthesized and studied YBaCuFe1-xMnxO5 samples doped with Mn, with the aim of increasing spin-orbit coupling effects, and found that the overall Fe/Cu cation disorder at the B-sites can be increased by doping without changing the sample preparation process. In YBaCuFe1-xMnxO5 samples prepared under the same conditions, the T-x magnetic phase diagram have been constructed in the range 10 K-500 K combining magnetometry, X-ray and neutron powder diffraction measurements. The tilting angles of the spins in the collinear, θcol, and spiral phases, θspiral, barely vary with temperature. In the collinear phase θcol is also independent of the Mn content. In contrast, the presence of Mn produces a progressive reorientation of the plane of the magnetic helix in the incommensurate phase, capable to transform the helicoidal spin ordering into a cycloidal one, which may critically determine the ferroelectric and magnetoelectric behavior in these compounds. Some of the observations are of interest for engineering and developing this family of potential high-temperature multiferroics.

Micromechanical analysis of thermoelastic and magnetoelectric composite and reinforced shells

A comprehensive micromechanical model for the analysis of structurally periodic and fully coupled magneto-electric and thermoelastic smart composite and reinforced thin shells is developed on the basis of Asymptotic Homogenization. Starting with the quasi-static approximation of Maxwell’s equations as well as force and thermal balance the model is decomposed into a macroscopic and a microscopic problem which are treated separately and sequentially even though the two scales are inherently coupled and co-existent in the original structure. The microscopic problem allows the computation of the effective coefficients and the macroscopic problem determines an asymptotic approximation of the field variables (stress, electric displacement, heat flux etc.). It is shown that in the limiting case of a thin elastic shell whereby any magnetoelectric and thermal behavior is suppressed, the derived model converges to the familiar classical shell model. As illustrated, the results of the model constitute an important refinement over previously established work.

Investigation of magnetic and ferroelectric properties along with the magnetoelectric coupling behavior for asserting a room temperature bi-phase composite as multiferroics

Various composites of nominal composition (1-x)Ba0.95Ca0.05TiO3 + xLi0.1Cu0.1Co0.1Zn0.6Fe2.1O4 have been prepared and studied thoroughly. X-ray diffraction and Rietveld refinement confirmed the presence of Ba0.95Ca0.05TiO3 and Li0.1Cu0.1Co0.1Zn0.6Fe2.1O4 phases in the composites. The microstructures have been investigated by field emission scanning electron microscopy. Temperature dependent dielectric constant shows two peaks, one is at 150 °C and another at 270 °C for x = 0.10 composite which resembles the characteristic ferroelectric and ferromagnetic transition peaks. A gradual progression of ferro-para electric transition towards room temperature is observed with doping. The non-Debye type dipole relaxations have been found. The linearity in the log(σAC) vs. log(ω) plots indicate that conduction is due to small polaron hopping. The real part of initial permeability increases with growing ferrite concentration but the cut-off frequency decreases. The magnetic property is also enhanced with doping content. The typical ferroelectric hysteresis loops have also seen with the addition of Li0.1Cu0.1Co0.1Zn0.6Fe2.1O4 up to x = 0.40. The impedance values are found to decreases in the Nyquist plots. The magnetoelectric voltage coefficient is obtained 287 × 103 V/mT for x = 0.15 at room temprrature. We found both ferromagnetic and ferroelectric hysteresis loops at room temperature. So, it confirms that the composites exhibit room temperature multiferroicity. This type of composites offers variety of opportunity for multifunctional devices application like hetero-structured read / write memory devices, switching devices and magnetic field sensing devices.

Resistive switching and multiferroic behavior of La0.5Pr0.5FeO3 ferrite thin films

This study examines resistive switching behavior and magnetoelectric coupling in La0.5Pr0.5FeO3 thin films obtained through the polymeric precursor method at a temperature of 500 °C for 2 h. The real and imaginary part of dielectric constant (ε′ and ε″) as a function of temperature demonstrate significant values with increasing temperature and can be caused by the ferroelectric ordering in the present system. The magnetic and dielectric measurements suggest a coupling between magnetic and electric dipoles at room temperature. The magnetization versus temperature curves under zero-field cooling (ZFC) and field cooling (FC) conditions suggest antiferromagnetic to ferromagnetic transition. The maximum magnetoelectric coupling value is ∼0.06 for H ∼1.7 T. By varying the applied electric field, we noted the resistive memory phenomenon from current-voltage (I–V) characteristics being reversibly switched between two stable resistance states. Such behavior can be ascribed to the electron hopping from Fe2+ to Fe3+ levels with oxygen vacancies present in the lattice, as evidenced using XPS analysis. These state-of-art analyses motivated us to study the introduction of praseodymium (Pr) in La3+ sites, considering that LaFeO3 shows paramagnetic behavior at room temperature. La0.5Pr0.5FeO3 thin films exhibited slightly ferromagnetic behavior associated with coupling between cations at the octahedral and tetrahedral sites with the coexistence of resistive switching and magnetoelectric coupling behavior.

Highly nonlinear magnetoelectric effect in buckled-honeycomb antiferromagnetic Co4Ta2O9

Strongly correlated materials with multiple order parameters provide unique insights into the fundamental interactions in condensed matter systems and present opportunities for innovative technological applications. A class of antiferromagnetic honeycomb lattices compounds, A4B2O9 (A = Co, Fe, Mn; B = Nb, Ta), have been explored owing to the occurrence of linear magnetoelectricity. From our investigation of magnetoelectricity on single crystalline Co4Ta2O9, we discovered strongly nonlinear and antisymmetric magnetoelectric behavior above the spin-flop transition for magnetic fields applied along two orthogonal in-plane directions. This observation suggests that two types of inequivalent Co2+ sublattices generate magnetic-field-dependent ferroelectric polarization with opposite signs. The results motivate fundamental and applied research on the intriguing magnetoelectric characteristics of these buckled-honeycomb lattice materials.

Spin-density studies of the multiferroic metal-organic compound [NH2(CH3)2][FeIIIFeII(HCOO)6

Polarized neutron diffraction is used to study in depth the magnetic properties of the heterometallic compound [NH2(CH3)2][FeIIIFeII(HCOO)6] and give insight into its magnetic behaviour, addressing open questions that will contribute to a better understanding of this attention-grabbing material and other related ones. Previous results revealed that upon cooling, the magnetic moments of the FeII and FeIII sites do not order simultaneously: the magnetization of the FeII site increases faster than that of the FeIII sites. Unpolarized neutron diffraction measurements at 2 K with no external field revealed some discrepancies in the saturation value of the magnetic signal on the FeIII sites and in the ferromagnetic moment along the c axis. These discrepancies could be related to the actual distribution of magnetic moment, since unpolarized neutron diffraction gives information on the magnetic moment localized only on the magnetic ions. Polarized neutron diffraction allows an analysis of the magnitude of the spin density over magnetic and non-magnetic ions (the organic ligand and the counterion), which can give a clue to explain the low saturation on the FeIII sites and the correlation with the physical measurements. The present study also contributes to the understanding of the magneto-electric behaviour of this compound, giving insight into the role of metal disorder in the origin of the structural phase transition, which is responsible for its antiferrolelectric order, and into the influence of spin-density delocalization on its magneto-electric properties, allowing a discussion of the alternative explanations given so far for its electric properties at low temperature.

Modeling of resonant magnetoelectric response in press-fit embedded ring composite

Magnetoelectric (ME) effect is a product property arising out of the interactions between the piezoelectric and the magnetostrictive phase. Multi-phase ME composites being multifunctional materials find use in myriad of applications. In this work, epoxy free two phase and three phase embedded ring ME composites have been fabricated by the press-fit technique. For a comparative study, three phase conventional epoxy bonded ring shaped composite of same dimensions have also been fabricated. Dynamic ME experiment has been conducted at room and elevated temperatures on all the prepared composites. It is shown that the epoxy free composite by virtue of the absence of epoxy shows a better resonant ME response at all temperatures. The significance of the Electromechanical Resonance (EMR) in the resonance behavior of the composites has also been highlighted. An analytical model in cylindrical coordinate system incorporating the temperature effects on the individual composite constituents and their interface coupling has been developed based on the concentric ring approach to predict the dynamic ME behavior of the epoxy free ring composite at different temperatures. The model has been further used to study the effect of volume fraction of the constituents on the ME response.

First-principles study on strain-controllable magnetoelectric coupling behaviour of two-dimensional BaTiO3 (001) ultrathin film with surface Ba vacancy

A first-principles approach was utilized to investigate the magnetoelectric coupling behaviour of two-dimensional BaTiO3 (001) ultrathin films with surface Ba vacancy under different strains. The total magnetic moment was suppressed when compressive strains were employed and had minimum values of 1.715 μB and 1.568 μB corresponding to uniaxial and biaxial strains, respectively; moreover, it exhibits an enhancement in the case of tensile strain. For shear strain, the magnetic moment fluctuated at ~1.78 μB. Furthermore, all partial magnetic moments and spontaneous polarization were functions of the strains except for the case of shear strain. Their conversion efficiency exhibited a regular varying tendency with increasing tensile strain. To explore electron spins, which can also be regulated, spin-orbit coupling calculations were carried out, showing that the changes in partial magnetic moments increased when the tensile strain was enhanced. Our study may pave a way for two-dimensional BaTiO3 to be applied in novel spin-based devices.

Strain and electric field control of the orbital and spin order in multiferroic $$\hbox {BiMnO}_3$$

The new frontier for spintronics is the realization of devices in which the spin can be controlled by electric fields. Multiferroics, materials exhibiting strong interplay between spin and orbital degrees of freedom, are candidates for the realization of such a paradigm. In this work, we study the magnetoelectric coupling in epitaxial $$\hbox {BiMnO}_3$$ thin films which exhibit a large saturation magnetization. By combining X-ray absorption spectroscopy data and theoretical modeling, we demonstrate that $$\hbox {BiMnO}_3$$ thin films have an improper magnetoelectric behavior, characterized by competing antiferromagnetic and ferromagnetic correlations. As a consequence, we show that in these materials the Mn-3d orbital and magnetic orders can be tuned via the ferroelectric polarization, opening perspectives for the realization of novel spintronic devices.

Effects of the interplay between R 4f and Fe 3d on magneto-electric behavior and high field magnetization in RFe2O4 (R = Yb, Tm)

The detailed magnetization behavior of RFe2O4 (R = Yb and Tm) have been investigated in a wide range of magnetic fields. In low temperature region, the temperature dependence of magnetization shows that the strength of the interaction between R 4f and Fe 3d ions is directly related to the R3+ ions, a distinct phase transition was observed at ~53 K in YbFe2O4 and no obvious one was observed in TmFe2O4 even cooling to 1.8 K. The possible interaction between R 4f and Fe 3d ions and their evolution with magnetic field were investigated by pulsed high magnetic field. Based on the structures of both FeO5 trigonal bipyramid and RO6 octahedron of RFe2O4, the competition between ferromagnetic double-exchange and antiferromagnetic superexchange among the R-R, R-Fe and Fe-Fe, especially the interplay between R and Fe ions, are discussed. The different R-Fe magnetic interaction betweenYbFe2O4 and TmFe2O4 is experimentally verified by impedance spectroscopy and dielectric spectroscopy. Finally, the high field magnetic phase diagrams of RFe2O4 (R = Yb, Tm) are proposed.

Temperature dependent crossover between positive and negative magnetoresistance in graphene nanocrystallines embedded carbon film

Monitoring magnetoelectric transport behavior of graphene material is critical in establishing a foundation for engineering next-generation spintronic devices. Here we report a temperature-dependent crossover between positive and negative magnetoresistance (MR) in graphene nanocrystallines embedded carbon film (GNC film), two sign changes of MRTotal (where MRTotal presents the measured MR value) value from positive MRTotal(+) to negative MRTotal(−) and then back to MRTotal(+) are observed as temperature varies from 2 K to 400 K. The crossover can be ascribed to the competitions among different origins including wave function shrinkage, spin-dependent Coulomb blockade effect and Lorentz force, which play dominant roles in low, medium and high temperatures, respectively. Moreover, it is revealed that GNC film with smaller GNs has larger positive contribution to MRTotal behavior, resulting in maximum MRTotal(+) of ∼8.1%. In contrast, GNC film with larger GNs dramatically contributes to negative MRTotal behavior, which obtains maximum MRTotal(−) of ∼ -1.1%. This work deepens understanding about the origin of MR of nanometer-sized graphene, which provides guidance for further magnetoelectric property improvement, and paves a way towards specific design of graphene derived spintronic devices with controllable MR behavior.

Structural, magnetic, and spin dynamical properties of the polar antiferromagnets Ni3−xCoxTeO6(x=1,2)

We present results of a multimethod investigation of the polar antiferromagnets $\mathrm{N}{\mathrm{i}}_{2}\mathrm{CoTe}{\mathrm{O}}_{6}$ and $\mathrm{NiC}{\mathrm{o}}_{2}\mathrm{Te}{\mathrm{O}}_{6}$, inspired by the colossal magnetoelectric effect present in $\mathrm{N}{\mathrm{i}}_{3}\mathrm{Te}{\mathrm{O}}_{6}$. Both compounds crystalize in the same polar space group $R3$ as $\mathrm{N}{\mathrm{i}}_{3}\mathrm{Te}{\mathrm{O}}_{6}$, preserving the crystal symmetry at least from room temperature down to 2 K. $\mathrm{N}{\mathrm{i}}_{2}\mathrm{CoTe}{\mathrm{O}}_{6}$ and $\mathrm{NiC}{\mathrm{o}}_{2}\mathrm{Te}{\mathrm{O}}_{6}$ undergo antiferromagnetic phase transitions at ${T}_{\mathrm{N}}=55$ and 52 K, and spin-flop transitions at an external magnetic field of approximately 8 and 4 T, respectively. Both compounds present an incommensurate antiferromagnetic helical structure with spins lying in the $ab$ plane, in contrast to the collinear one along the $c$ axis in $\mathrm{N}{\mathrm{i}}_{3}\mathrm{Te}{\mathrm{O}}_{6}$. Moreover, dielectric anomalies are observed at their antiferromagnetic phase transitions, suggesting a magnetoelectric behavior. Spin and lattice dynamics studies by a combination of infrared, Raman, and terahertz spectroscopies were performed. Below ${T}_{\mathrm{N}}$, in both $\mathrm{N}{\mathrm{i}}_{2}\mathrm{CoTe}{\mathrm{O}}_{6}$ and $\mathrm{NiC}{\mathrm{o}}_{2}\mathrm{Te}{\mathrm{O}}_{6}$, low-frequency spin excitations extremely sensitive to external magnetic field were observed. At least one of these magnons was simultaneously seen in Raman and THz spectra of both compounds, therefore we propose to assign them to electromagnons.

Structural, magnetic and dielectric properties of cobalt doped GdFeO3 orthoferrites

In this present work deals with the structural and magnetoelectric behaviour of Cobalt substituted GdFeO3 orthoferrites synthesized by solid state reaction technique. X-ray diffraction and FTIR studies of GdCoxFe1-xO3 (0 ≤ x ≤ 0.3) orthoferrites disclosed the orthorhombic Pbnm structure and Co induced vibrational modes in GdFeO3 orthoferrites respectively. Cationic displacements confirmed from the crystallite size calculations and deviations in lattice parameters affected the magnetic and electrical nature of the GdCoxFe1-xO3 (0 ≤ x ≤ 0.3) orthoferrites. Co substitution promoted a drastic improvement in the magnetic nature of Cobalt substituted GdFeO3 orthoferrites than that of GdFeO3. Antiferromagnetic GdFeO3 has turned out to be strong ferromagnetic material on Co substitution. Higher coercive values 1620.4 Oe and 4035.06 Oe were recorded for GdCo0.2Fe0.8O3 ferrites whereas for GdFeO3 they were seen to be 527.62 Oe and 360.61 Oe at 300K and 150K temperatures respectively. Dielectric studies revealed a decrease in dielectric constant and loss tangent values with frequency at room temperature. AC conductivity is seen to be increasing at higher frequencies and a maximum value is obtained at Co content of x = 0.2. The significance of cobalt in mutating the structural, magnetic and electrical properties of GdCoxFe1−xO3 (0 ≤ x ≤ 0.3) ferrites is clearly seen by making them useful for high frequency applications.

Design, analysis, and optimization of a magnetoelectric actuator using regression modeling, numerical simulation and metaheuristics algorithm

In this study, a new method was proposed for the design of composite magnetoelectric actuator. Design of experiment (DOE) was utilized to investigate the mutual effect of geometric parameters. Moreover, the effect of impedance phase angle, magnetic field, and bias field were studied through finite element (FE) modeling. Resonance frequency, displacement value, magnetoelectric coefficient, and mode shape were considered as response variables. Analysis of variance (ANOVA), regression modeling and response surface method (RSM) were used to investigate the pair-wise effect of input parameters on the response variables. ANOVA results showed that the magnetoelectric length and piezoelectric thickness are the most important parameters affecting the magnetoelectric performance. The optimization process was performed using Metaheuristics algorithm. Optimum results were verified using magnetoelectric measurement setup and Laser Doppler Vibrometry device. The accuracy of the FE model in resonance frequency prediction was estimated at 97%. The prediction error of the FE model for the magnetoelectric voltage parameter was 14.6%, which was about 12.9% better than the regression model. The confirmation test showed that the regression modeling can only predict magnetoelectric behavior and for determining magnetoelectric performance, a precise FE model would be more reliable. Such proposed optimization technique can be used in the design of magnetoelectric composites.

Effect of co-sintering time on magnetoelectric response of Pb0.895Sr0.06La0.03(Zr0.56,Ti0.44)O3 multilayer–Ni0.6Zn0.4Fe2O4 composite fabricated by tape casting

The effect of cosintering time on magnetoelectric (ME) behavior of Sr, La doped lead zirconate titanate multilayer–nickel zinc ferrite composites fabricated by the tape-casting method has been investigated. Powders of individual phases, viz., Pb(1 − x − 3y/2)SrxLay(Zrz,Ti(1 − z))O3 (PSLZT) and Ni0.6Zn0.4Fe2O4 (NZFO), were prepared by the solid-state reaction method, and their respective thick films were fabricated by the tape-casting method. A PSLZT multilayer having Pt inner electrodes stacked onto NZFO laminated composites was cosintered at 1060 °C for 1–10 h. Cosintered, warpage-free, and delamination-free layered composite thick film structures were analyzed by scanning electron microscopy. Microstructure at the interface could be crucial for better magnetoelectric coupling, and, hence, the microstructure of the interface was analyzed as a function of sintering time at a fixed sintering temperature. Elemental mapping revealed a negligible interdiffusion between PSLZT and NZFO phases. Composites cosintered for different time durations were analyzed for their ferroelectric behavior. Further, impedance spectrum analysis indicated clear resonance behavior for the composites cosintered for 2 and 6 h. All the composites were analyzed for magnetoelectric properties at different applied DC magnetic fields having a superimposed ac magnetic field of a fixed frequency and different ac frequencies at fixed DC magnetic fields. The magnetoelectric coefficient was found to increase with an increase in the sintering time of up to 6 h and an ME coefficient of 230 mV/cm Oe with a self-bias nature. Magnetoelectric resonance behavior was also studied, which showed an ME voltage coefficient of 6 V/cm Oe for composites sintered for 6 h at resonance.

In-plane magnetoelectric response in bilayer graphene

A graphene bilayer shows an unusual magnetoelectric response whose magnitude is controlled by the valley-isospin density, making it possible to link magnetoelectric behavior to valleytronics. Complementary to previous studies, we consider the effect of static homogeneous electric and magnetic fields that are oriented parallel to the bilayer's plane. Starting from a tight-binding description and using quasi-degenerate perturbation theory, the low-energy Hamiltonian is derived including all relevant magnetoelectric terms whose prefactors are expressed in terms of tight-binding parameters. We confirm the existence of an expected axion-type pseudoscalar term, which turns out to have the same sign and about twice the magnitude of the previously obtained out-of-plane counterpart. Additionally, small anisotropic corrections to the magnetoelectric tensor are found that are fundamentally related to the skew interlayer hopping parameter $\gamma_4$. We discuss possible ways to identify magnetoelectric effects by distinctive features in the optical conductivity.

Residual Strain-Mediated Multiferroic Properties of Ba0.85Ca0.15Zr0.9Ti0.1O3/La0.67Ca0.33MnO3 Epitaxial Heterostructures.

In this study, artificial multiferroic Ba0.85Ca0.15Zr0.1Ti0.9O3/La0.67Ca0.33MnO3(BCZT/LCMO) epitaxial heterostructures were deposited on Nb-doped SrTiO3 substrates using pulsed laser deposition. The epitaxial growth of the heterostructures on the substrate was demonstrated by XRD, RSM, and TEM analyses, which displayed decreasing residual strain with increasing BCZT layer thickness. The electrical, magnetic, and magnetoelectric properties of the epitaxial heterostructures were investigated in detail, and they were sensitive to the varying BCZT layer thickness in terms of residual strain. The multiferroic nature of the heterostructures was demonstrated by ferroelectric and ferromagnetic hysteresis loops. Strain-mediated magnetoelectric behavior was observed in the epitaxial heterostructures. Finally, dielectric properties were enhanced in the heterostructures over the BCZT single layer film, and the maximum magnetoelectric coefficient of the heterostructures was 206.5 mV/cm·Oe.

Investigation of magnetoelectric effect in lead free K0.5Na0.5NbO3-BaFe12O19 novel composite system

Lead-free magnetoelectric composites (1−x)K0.5Na0.5NbO3—(x)BaFe12O19 (x = 30, 40, and 50 wt%) are synthesized using solid state reaction method. X-ray diffraction (XRD) patterns confirm formation of diphase composites. Field emission scanning electron microscopy (FE-SEM) gives information about grain size, connectivity, and microstructure of constituent phases. Dielectric parameters of composite samples are studied as a function of temperature and the transition temperatures corresponding to both the constituent phases are observed in the composite samples. Dielectric constant has been found to decrease with addition of ferrite. Room temperature multiferroic behaviour has been confirmed using P-E and M-H hysteresis loops and magnetoelectric measurement. Polarization is found to decrease; however, magnetization increases with ferrite weight percentage. The highest αME of 4.08 mV/(cm·Oe) is obtained for x = 30 wt% composite and it is realized that ferrite content significantly affects magnetoelectric behaviour.