Magnetoelectric Behavior Research Articles

An overview of La2NiMnO6 double perovskites: synthesis, structure, properties, and applications

Multifunctional materials having simultaneous electrical and magnetic assembling have been attempted by numerous researchers for next-generation electronic appliances. Among such materials, rare earth metals containing double perovskites, such as La2BB′O6 (B = Ni, B′ = Mn) are the utmost studied materials. In this review, we have summarized various physicochemical aspects of La2NiMnO6 such as crystal structure, electrical, magnetic, and magneto-transport behavior from earlier studies under several experimental conditions. Magnetic field and temperature effects on magnetoelectric and electronic behavior of this material are described. We discuss how the morphology in the form of bulk phase, thin layer, and nanoparticles affect such physicochemical properties of this material. We also highlighted the role of cation order–disorder at ‘B’ sites and the probability of the resulting numerous electronic behavior in this type of material and expectation on basic understanding of Ni–O–Mn electronic, as well as magnetic properties. The prospective applications of this material over conventional substances in solar cells, electric tunable devices, biomolecular and gas sensing technologies are also ascribed. The motivation of the present review is to sum up all such behaviors of La2NiMnO6 to find its possible applications in new areas of material research and the directions of future works.

Improvement of the magneto-electric effect of composites loaded with different magnetic particles for current sensor applications

This article proposes a methodology to improve the magneto-electric effect of a poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFe) copolymer, doped with nanoparticles of nickel (Ni) and nickel iron (NiFe). The preparation of the composite films were achieved through the solvent casting approach. First, P(VDF-TrFe) powders and (Ni and NiFe) nanoparticles are dispersed in dimethyl formamide (DMF) as a solvent to form a homogeneous solution. Then, the solution obtained is deposited on a flexible substrate by a spin coating process. After that, the NiFe doped composites are corona polarized, to improve the magneto-electric response of these composites. The purpose of this work is to investigate the influence of the magnetic charges added in the P(VDF-TrFe) copolymer, and to reveal the effect of corona charging (polarization) on the magneto-electric behavior of the used composites. The obtained results in this article show that both the doping and the electric polarization (piezo coefficient) significantly affect the generated alternating current during the application of an alternating magnetic field. However, the magneto-electric response of composites increases by doping and charging via corona poling effect and also by increasing the excitation frequency and the magnetic field amplitude. In addition, the magneto-electric responses of all composites after corona polarization were also discussed. This indicates that the magneto-electric coefficient and the current can be increased with polarized composites. A good response is observed for P(VDF-TrFe) + 3% Ni with a piezoelectric coefficient d33 = 21.2 (pC/N)

Magnetoelectric hysteresis of a bilayered magnetoelectric composite

A bilayered magnetoelectric composite has been fabricated by bonding a magnetostrictive layer Terfenol-D and a piezoelectric layer Pb(Zr0·52Ti0·48)O3 together. The magnetoelectric hysteresis behavior of the magnetoelectric composite has been investigated. The results show that the magnetoelectric voltage coefficients of the composite are strongly affected by the bias magnetic field and test period. The magnetoelectric voltage coefficients with the bias magnetic field exhibit hysteresis over a test period, forming hysteresis loops with an anticlockwise direction sweep. The test time hysteresis caused by a fast varying bias magnetic field can be reduced by prolonging the test period. The observed coercive field, remanence and ratio of the remanence of the magnetoelectric hysteresis loops with the test period obey an exponential decay law. In addition, the bias magnetic field dependence of magnetoelectric hysteresis loops is found to be associated with magnetic hysteresis loops. These findings provide some ideas not only for practical applications, but also for the magnetoelectric effect examinations of magnetoelectric composites.

Persistence of large magnetodielectric coupling anomalies and multiferroicity for significant dilution of Tb sublattice by Y in Tb2BaNiO5

We report temperature dependence of dc magnetization, heat capacity, dielectric, magnetodielectric (MDE) coupling, and pyrocurrent on polycrystalline specimens resulting from a gradual dilution of Tb sublattice by Y in an exotic multiferroic Haldane spin-chain system, Tb2BaNiO5, viz., for the series Tb2−xYxBaNiO5 (x = 0.1, 0.2, 0.5, 1, and 1.5). Among various observations, the ones to be stressed are as follows: (i) The Néel temperature (TN1 = 63 K) and the second magnetic feature occurring at (TN2) 25 K get reduced to lower temperatures with increasing x in a linear fashion, with a concomitant lowering of multiferroicity onset temperature below TN2, scaling essentially with x. This finding emphasizes that local effects due to Tb play a major role on multiferroicity. Clearly, 4f dominates to determine this phenomenon—a rare finding in this field. (ii) The magnitude of the change (Δɛ′) in the dielectric constant surprisingly gets maximized for x = 0.1 with respect to that of the parent compound, attaining a relatively large value of about 22% at 15 K for a field of 100 kOe, thereby revealing that a delicate balance of nonmagnetic doping or defects in favorable cases can enhance MDE coupling. (iii) Nonmonotonic changes in Δɛ′ with a magnetic field, also a changing sign for some compositions, reveal interesting metamagnetodielectric behavior. (iv) The magnetoelectric behavior of x = 1.5 composition is found to be somewhat peculiar with respect to that of other compositions. Thus, this solid solution reveals exotic magneto(di)electric coupling anomalies.

Influence of clamping effect in BaTiO3 film on the magnetoelectric behavior of layered multiferroic heterostructures

The experimental observation and analysis for the influence of clamping effect on the magnetoelectric properties of the bilayer La0.7Sr0.3MnO3/BaTiO3 (LSMO/BTO) and trilayer LSMO/BTO/LSMO heterostructures were reported. Because the significant two-dimensional clamping effect caused by the lattice mismatch of the constituting layers, the relative dielectric constant and the ferroelectric coercive field of the trilayer heterostructure was lower than that of the bilayer one. Furthermore, the variation in ME voltage coefficient (αE) as a function of frequency for the two heterostructures was found to exhibit a monotonous increasing tendency. The value of αE for the trilayer heterostructure was little lower than that of the bilayer one, that is because the clamping effect suppressed both the ferroelectric properties of BTO and the transferred strain at the hetero interface.

Magnetoelectric behavior from cluster multipoles in square cupolas: Study of Sr(TiO)Cu4(PO4)4 in comparison with Ba and Pb isostructurals

We report our combined experimental and theoretical study of magnetoelectric properties of an antiferromagnet Sr(TiO)Cu$_4$(PO$_4$)$_4$, in comparison with the isostructurals Ba(TiO)Cu$_4$(PO$_4$)$_4$ and Pb(TiO)Cu$_4$(PO$_4$)$_4$. The family of compounds commonly possesses a low-symmetric magnetic unit called the square cupola, which is a source of magnetoelectric responses associated with the magnetic multipoles activated under simultaneous breaking of spatial inversion and time reversal symmetries. Measuring the full magnetization curves and the magnetic-field profiles of dielectric constant for Sr(TiO)Cu$_4$(PO$_4$)$_4$ and comparing them with the theoretical analyses by the cluster mean-field theory, we find that the effective $S=1/2$ spin model, which was used for the previous studies for Ba(TiO)Cu$_4$(PO$_4$)$_4$ and Pb(TiO)Cu$_4$(PO$_4$)$_4$, well explains the experimental results by tuning the model parameters. Furthermore, elaborating the phase diagram of the model, we find that the square cupolas could host a variety of magnetic multipoles, i.e., monopole, toroidal moment, and quadrupole tensor, depending on the parameters that could be modulated by deformations of the magnetic square cupolas. Our results not only provide a microscopic understanding of the series of the square cupola compounds, but also stimulate further exploration of the magnetoelectric behavior arising from cluster multipoles harboring in low-symmetric magnetic units.

Realization of Wideband Magnetoelectric Response Utilizing Three-Phase Particulate Ceramics

This paper is aimed at acquiring functional ceramics with broadband magnetoelectric (ME) response for sensing wide-range of dc bias magnetic field. Three-phase particulate ceramics CoFe2O4/Ni0.8Zn0.2Fe2O4/Bi0.5Na0.4K0.1TiO3 (CFO/NZFO/BNKT) were fabricated, and the effect of magnetostrictive phase on the piezoelectric, magnetic, and ME properties were investigated systematically. Separated phases and homogeneous microstructure of the magnetostrictive and piezoelectric phases were confirmed. The variation in magnetostrictive coefficient with dc magnetic field was found to be markedly dependent on the relative content of magnetostrictive microparticles. By merging the nonlinear piezomagnetic response of the two ferrite components together, the ME composites present dual-peak bands. A wide-range ME coefficient was achieved over a magnetic range of 1800 Oe with large ME value of 20 mV/cm Oe. This field-conversion broadband ME behavior indicates that three-phase particulate ME ceramics are quite preferable for practical applications in magnetic field sensor.

Anomalous ferroelectricity and strong magnetoelectric coupling in CoFe2O4-ferroelectric composites

A unique averaging mechanism is established for estimation of magnetoelectric coupling coefficient (α) by studying the effect of magnetic field on ferroelectric hysteresis loop measurements. The highest value of α obtained using this mechanism is 22 mV/cm/Oe at a field of 5000 Gauss for CoFe2O4-10%BaTiO3 (CFO-10BT) composite and is in agreement with the recent reported studies. The composites of CFO-BT exhibit interplay of magnetism, ferroelectricity and display strong magnetoelectric behaviour arising out of charge disordering. The structural studies from the combination of XRD, Raman and FTIR measurements of CFO-BT composites establishco-existence of cubic and tetragonal phase with space group. The ferroelectric studies display a low leakage charge density of 0.0031 μC/cm2 and prevalent asymmetry arising due to spatial disordering of charge distribution. Furthermore, the magnetic measurements reveal an enormous increase in the coercivity of CFO-30BT composite which is identified in terms of movement of ferromagnetic domains arising due to inclusion of trapping centres of BT in CFO.

Magnetic structural unit with convex geometry: A building block hosting an exchange-striction-driven magnetoelectric coupling

We perform a combined experimental and theoretical study of a magnetic-field ($B$) induced evolution of magnetic and ferroelectric properties in an antiferromagnetic material Pb(TiO)Cu$_4$(PO$_4$)$_4$, whose structure is characterized by a staggered array of Cu$_4$O$_{12}$ magnetic units with convex geometry known as square cupola. Our experiments show a $B$-induced phase transition from a previously reported low-$B$ linear magnetoelectric phase to a new high-$B$ magnetoelectric phase, which accompanies a 90$^\circ$ flop of electric polarization and gigantic magnetodielectric effect. Moreover, we observe a $B$-induced sign reversal of ferroelectric polarization in the high-$B$ phase. Our model and first-principles calculations reveal that the observed complex magnetoelectric behavior is well explained in terms of a $B$-dependent electric polarization generated in each Cu$_4$O$_{12}$ unit by the so-called exchange striction mechanism. The present study demonstrates that the materials design based on the magnetic structural unit with convex geometry deserves to be explored for developing strong magnetoelectric couplings.

Magnetoelectric coupling in the gapless NH4CuCl3

NH4CuCl3, a well-studied antiferromagnet best known for its gapless magnetization and unusual magnetization plateaus, is shown here to exhibit magnetoelectric behavior below the antiferromagnetic transition temperature of 1.3 K. This is based on magnetic field and temperature dependent capacitance measurements made at millikelvin temperatures, along with the appearance of spontaneous polarization and electric-field reversible pyroelectric current. The possession of both long-range magnetic and dielectric order, combined with magnetoelectric coupling, renders this material a rather unique Cu-based multiferroic and serves as a unique template for the design of such materials.

Theoretical and experimental analysis of temperature dependent nonlinear behaviour of tri-layered magnetoelectric composites

In this work, experiments have been performed to study the magneto-mechanical behaviour of (Tb0.3Dy0.7Fe2) under various operating temperatures. Based on the experimental results, a three dimensional nonlinear constitutive model under thermodynamic framework have been developed to capture the thermo-magneto-mechanically coupled behaviour. Then, the model parameters have been identified using least square approximation. Later, using the developed model, a homogenisation procedure has been introduced to simulate magnetoelectric (ME) coupling behaviour for various temperature and volume ratio of composition for different configurations (T-T, L-T, T-L, L-L) in layered ME composites. In a particular configuration (say L-T) is represented by referring first letter (L) as the direction of external magnetic field and the second letter (T) as the direction of polling in the piezoelectric material. Consequently, an experimental setup has been established to capture the ME voltage coefficient at L-T mode under different operating temperatures. Comparison between the experimental data and the simulation results shows good agreement with each other. Comparing the ME coupling behaviour for various configurations, L-L and L-T configurations are observed to have higher coupling factor.

Domain switching in single-phase multiferroics

Multiferroics are a time-honoured research subject by reason for their tremendous application potential in the information industry, such as in multi-state information storage devices and new types of sensors. An outburst of studies on multiferroicity has been witnessed in the 21st century, although this field has a long research history since the 19th century. Multiferroicity has now become one of the hottest research topics in condensed matter physics and materials science. Numerous efforts have been made to investigate the cross-coupling phenomena among ferroic orders such as ferroelectricity, (anti-)ferromagnetism, and ferroelasticity, especially the coupling between electric and magnetic orderings that would account for the magnetoelectric (ME) effect in multiferroic materials. The magnetoelectric properties and coupling behavior of single phase multiferroics are dominated by their domain structures. It was also noted that, however, the multiferroic materials exhibit very complicated domain structure...

Enhanced magnetoelectric coupling in Ti and Ce substituted lead free CFO-BCZT laminate composites

Lead-free multiferroic composites with enhanced magnetoelectric properties and sensitivity have potential for various multifunctional devices. The magnetoelectric behaviour of CoFe2O4-(Ba0.85Ca0.15) (Zr0.1Ti0.9)O3, (CFO-BCZT) and substituted CFO-BCZT laminate composites prepared by epoxy bonding are investigated in this study. Magnetostrictive CoFe2O4 (CFO) substituted with Ti (CTFO) resulted in a very high piezo-magnetic coefficient (q) of ∼290 × 10−9 Oe−1. Lead free piezoelectric (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 [BCZT] substituted with Ce4+ (BCZCT) showed improved piezoelectric coefficients of d33 ∼ 675 pC/N and g33 ∼13 mV m/N. Two new trilayer multiferroic laminates were developed with a (2-2) composite connectivity by combining the pure and substituted ferroic phases. Magnetostrictive, ferroelectric, piezoelectric and magnetoelectric properties of CFO-BCZT and CTFO-BCZCT laminate composites were measured and compared in here. CTFO-BCZCT composite exhibited a large magnetoelectric response with a high ME coefficient (αME) of ∼950 mV/cm.Oe and also showed an improved magnetoelectric sensitivity at lower magnetic fields, making it a potential lead-free material for magnetoelectric sensing applications.

Phase transitions and magnetoelectric coupling in BiFe1−xZn x O3 multiferroics

Multiferroic BiFe1−xZn x O3 ceramics were prepared by solution combustion method. Their structure, magnetoelectric, dielectric, magnetic, thermal characteristics were studied. The magnetic M(T) and heat capacity C p (T) measurements demonstrate an antiferromagnetic to paramagnetic phase transition (T N ) around 635 K. The anomaly on the temperature dependence of the dielectric constant near T N was observed, which could be induced by the magnetoelectric coupling between electric and magnetic ordering. The magnetoelectric behavior was also confirmed by the linear relation between Δe and M2, which is in the agreement of the Ginzburg-Landau theory for the second-order phase transition.

Bias magnetic field and test period dependences of direct and converse magnetoelectric hysteresis of tri-layered magnetoelectric composite

The direct and converse magnetoelectric hysteresis behavior for a tri-layered composite has been comparatively investigated and significant similarities have been observed. The results show that both the direct and converse magnetoelectric hysteresis is deeply affected by the bias magnetic field and test period. The test time hysteresis caused by a fast varying bias magnetic field can be reduced by prolonging the test period. The observed coercive field, remanence, and ratio of remanence of the direct and converse magnetoelectric effects with the test period obey an exponential decay law. A hysteretic nonlinear magnetoelectric theoretical model for the symmetrical tri-layered structure has been proposed based on a nonlinear constitutive model and pinning effect. The numerical calculation shows that the theoretical results are in good agreement with the experimental results. These findings not only provide insight into the examination and practical applications of magnetoelectric materials, but also propose a theoretical frame for studying the hysteretic characteristics of the magnetoelectric effect.

Voltage-Tuned Transport Properties and Ferromagnetic Resonance in Lanthanum-Strontium-Manganite/Lead-Magnesium–Niobate-Lead-Titanate Multiferroic Heterostructures

We demonstrate piezostrain-induced modulation of transport and ferromagnetic resonance (FMR) properties in the La 0.5Sr0.5MnO3 (LSMO5)/0.7Pb(Mg1/3Nb2/3)O3 -0.3PbTiO3 (PMN-PT) (0 0 1) multiferroic heterostructures. The poling strain leads to the enhancement of the double exchange interaction and the reduction of Jahn–Teller electron-lattice distortion in the LSMO5 film, showing a maximum resistance decrease of 27% at 105 K, around which temperature the maximum magnetoresistance change of 10% is tuned by the piezostrain. The FMR response to the strain changes is probed by temperature-dependent electron spin resonance spectra, showing the largest FMR field shift of 220 Oe at the Neel temperature of 193 K. The magnetoelectric coupling behavior at the antiferromagnetic phase of LSMO5 film was dominated by the two-magnon scattering effect, which provides a new route for voltage-controllable magnetism in future spintronic devices.

Emergent magnetoelectricity in soft materials, instability, and wireless energy harvesting.

Magnetoelectric materials that convert magnetic fields into electricity and vice versa are rare and usually complex, hard crystalline alloys. Recent work has shown that soft, highly deformable magnetoelectric materials may be created by using a strain-mediated mechanism. The electromagnetic and elastic deformation of such materials is intricately coupled, giving rise to a rather rich instability and bifurcation behavior that may limit or otherwise put bounds on the emergent magnetoelectric behavior. In this work, we investigate the magneto-electro-mechanical instability of a soft dielectric film subject to mechanical forces and external electric and magnetic fields. We explore the interplay between mechanical strain, electric voltage and magnetic fields and their impact on the maximum voltage and the stretch the dielectric material can reach. Specifically, we present physical insights to support the prospects to achieve wireless energy harvesting through remotely applied magnetic fields.

Electrically controllable spin filtering based on superconducting helical states

The magnetoelectric effects in the surface states of the three-dimensional (3D) topological insulator (TI) are extremely strong due to the full spin-momentum locking. Here the microscopic theory of S/3D TI bilayer structures in terms of quasiclassical Green's functions is developed. On the basis of the developed formalism it is shown that the DOS in the S/TI bilayer manifests giant magnetoelectric behavior and, as a result, S/3D TI heterostructures can work as nonmagnetic fully electrically controllable spin filters. It is shown that due to the full spin-momentum locking the amplitudes of the odd-frequency singlet and triplet components of the condensate wave function are equal. The same is valid for the even frequency singlet and triplet components. We unveil the connection between the odd-frequency pairing in S/3D TI heterostructures and magnetoelectric effects in the DOS.

Enhanced magnetoelectric response from lead-free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 – CoFe2O4 laminate and particulate composites

Lead free multiferroic composite (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 - CoFe2O4 was prepared in two different connectivity schemes, particulate and laminates and their magnetoelectric properties have been investigated in this study. Lead free piezoelectric (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) and ferrimagnetic CoFe2O4 (CFO) phases were synthesized by sol-gel and combustion techniques respectively. Particulate composite was prepared by mechanical mixing of BCZT and CFO phases in equal weight fraction. The laminate structures (bilayer and trilayer) was developed by bonding BCZT with CFO layers by epoxy bonding. High piezoelectric coefficients, d33 ~ 630 pC/N, g33 ~11mVm/N, and magnetostricition ~183ppm were obtained for the laminate composite. Magnetoelectric measurements revealed a large ME response for the trilayer laminate composite especially at high frequency, where the electro-mechanical resonance appears for the composite. A high magnetoelectric coefficient (αME) ~803mVcm−1Oe−1 was obtained for the trilayer laminate composite which was 8 times higher than that of the particulate composite, αME ~ 104mVcm−1Oe−1. Bilayer laminate showed a maximum (αME) coefficient of ~ 615mVcm−1Oe−1. The magnetoelectric behavior of all the three composites is discussed and compared in this study.

Interfacial coupling in multiferroic BiFeO3 and ferromagnetic La2/3Sr1/3MnO3 thin films

Antiferromagnetic/Ferromagnetic coupling mechanics have been studying by growing successfully BiFeO3/La2/3Sr1/3MnO3 bilayers on SrTiO3 single crystals by using rf and dc sputtering technique at pure oxygen pressures. We have investigated the magnetic behaviour of this samples, field cooling loops evidence interfacial coupling effect when antiferromagnetic ferroelectric BiFeO3 is placed in contact with ferromagnetic La2/3Sr1/3MnO3 indicate by the shift of the magnetization loop to negative values of the applied magnetic field. Our samples exhibited an exchange bias of 76Oe at 5K after field cooling the sample under 5000Oe. Temperature dependence of the exchange bias field showed exponential decay. The BFO/LSMO bilayer exhibits excellent ferroelectric behaviour (Ps=65μC/cm2 at 4V and 100Hz). Coexistence of ferroelectric and ferromagnetic properties in the BFO/LSMO bilayer make it a promising candidate system for applications where the magnetoelectric behaviour is required.