Magnetoelectric Properties Research Articles

Fe+3- Mn+4 and Ti+4- Mn+3 interactions effect on the structural, electronic, magnetic and magnetoelectronic properties of perovskite manganites

In this study, we report room temperature positive magneto capacitance due to Ti +4 and Mn +3 valence states interactions in La 0.7 Pb 0.3 Mn 0.4 Ti 0.6 O 3+δ (δ = 0.15) i.e. La 0.66 Pb 0.3 Mn 0.4 Ti 0.56 O 3 and negative magneto capacitance due to Fe +3 and Mn +4 valance states interactions in Fe doped composition La 0.7 Pb 0.3 Mn 0.4 Fe 0.6 O 3. Rietveld analysis shows similar structural properties of Fe and Ti doped compositions. Synchrotron X-ray absorption spectroscopy (XAS) studies show (i) the presence of Ti +4 , Mn +3 and Mn +4 in La 0.66 Pb 0.3 Mn 0.4 Ti 0.56 O 3 and (ii) Fe +3 , Mn +3 and Mn +4 in La 0.7 Pb 0.3 Mn 0.4 Fe 0.6 O 3 . At room temperature, Fe doped composition shows nearly three times more magnetic moment in comparison to the magnetic moment of Ti doped composition. La 0.7 Pb 0.3 Mn 0.4 Fe 0.6 O 3 composition shows maximum ∼64% negative magneto capacitance while La 0.66 Pb 0.3 Mn 0.4 Ti 0.56 O 3 shows maximum ∼ 12% positive magneto capacitance. Size, quantity, number of d electrons and type of interactions among the valence states Fe +3 (0.645 Å), Ti +4 (0.605 Å), Mn +3 (0.645 Å), Mn +4 (0.53 Å) affect the electronic, magnetic and magnetoelectric properties of La 0.66 Pb 0.3 Mn 0.4 Ti 0.56 O 3 and La 0.7 Pb 0.3 Mn 0.4 Fe 0.6 O 3 manganites.

Piezoelectric and magnetoelectric properties of PVDF/NiFe2O4 based electrospun nanofibers for flexible piezoelectric nanogenerators

In this study, flexible piezoelectric nanogenerators (PNGs) were fabricated using the composite fibers which were prepared by combining polyvinylidene difluoride (PVDF) and nickel ferrite (NiFe2O4) nanoparticles (NPs) at a concentration of 1, 3, 5, 7, and 10 wt%. The piezoelectric properties of PNG indicate that the PVDF/NiFe2O4 fibers containing NiFe2O4 NPs at a concentration of 10 wt% has a higher power efficiency of 5.4% at 20 Hz compared to that of the pure PVDF fibers at 10 Hz, under the same resistive load of 2.5 MΩ. The magnetoelectric properties of PNG show that the PNG with PVDF+7 wt%NiFe2O4 supplied the highest electrical power of 0.40 μW under a resistive load of 750KΩ while it reached a maximum voltage value of 17.50 mV at the same load resistive load for a low-level magnetic field of 50 Hz frequency.

A Blockwall‐Type Layered Bis(dithiolato)nickelate Radical Salt Exhibiting High‐ and Two‐Dimensional Antiferromagnetic Coupling Feature

Comprehensive SummaryThe family of [M(dmit)2]‐ salts (dmit2‐ = 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate; M = Ni, Pd and Pt) generally show novel magnetic, electric, magnetoelectric and photoelectric properties. Herein, a blockwall‐type layered [Me3S][Ni(dmit)2] radical salt (1; Me3S+ = trimethylsulfonium) was prepared and characterized by microanalysis, IR spectroscopy, thermal analysis, powder and single crystal X‐ray diffraction techniques. Salt 1 crystalizes in triclinic space group P‐1, with two pairs of [Ni(dmit)2]‐ and Me3S+ ions in an asymmetric unit. The anions form blockwall‐type monolayer, being parallel to crystallographic (0 1 1) plane, and the cations are accommodated in the spaces of anion monolayer. Salt 1 features a two‐dimensional S = ½ antiferromagnetic (AFM) spin system with θ = ‐97.8(1) K and a semiconductor with σ ≈ 10‐4 S·cm‐1 and activation energy Ea = 0.24(1) eV in 308—368 K. 1 shows two‐step dielectric relaxations ranged from 173—373 K and 1—107 Hz for the dipole motions of two different polar cations. Most importantly, the dielectric constant of 1 reaches to ~17, with high‐κ nature. This study suggests the possibility of achieving high‐κ materials by introducing polar and low rotation barrier components into van der Waals crystal and high‐κ [Ni(dmit)2]‐‐based electrode materials for applications in supercapacitors.

Structural, dielectric, magnetic and magnetoelectric properties of the PFN-PT/Co[formula omitted]Ni[formula omitted]Fe2O[formula omitted] multiferroic composites

Structural, magnetic, magnetoelectric (ME), dielectric and ferroelectric properties of multiferroic composites based on ferroelectric PFN-PT and ferrimagnetic Co1−xNixFe2O4 have been studied. By changing the Ni content, we tuned the magnetic anisotropy of the magnetic part and studied its role on the magnetoelectric response of the composite. Our results showed that the ME voltage coefficient in the composites of 0.7(PFN-PT)/0.3(NixCo1−xFe2O4) is highly influenced by the content of Ni. The maximum value of ME voltage coefficient, 11.32 mV/(cm.Oe), was obtained for the composite with x=1 and the minimum value, 5.32 mV/(cm.Oe), was found for the composite with x=0.75. In addition, by changing the Ni content, we observed that the behavior of Hmax, the field in which maximum ME voltage was observed, follows the trend of coercivity Hc. We interpreted the results in the framework of dynamic piezomagnetic coefficient and also cation distribution in the spinel structure of the magnetic phase.

Effect of mechanical milling on magnetic, dielectric and magneto-electric properties of Z- type (Ba, Sr) hexaferrites

The Z-type hexaferrites Sr3Co2Fe24O41 (SCFO) and Ba3Co2Fe24O41 (BCFO) were prepared via sol-gel method and were ball milled for different duration to study the effects of reduction in particle on the physical properties of these compounds. The phase formation was confirmed by using X-ray diffraction (XRD) whereas Scanning Electron Microscopy (SEM) was employed to analyze the surface morphologies of these samples. Magnetization measurements i.e. (M-H) at room temperature were performed by using Vibrating Sample Magnetometer (VSM) and it is observed that the magnetic coercive field (Hc) has increased with reduction in particle of the samples i.e., with ball milling. Magneto electric effects of (Ba, Sr) Z-type hexaferrites at room temperature were measured indirectly by examining the change in polarization (P-E loop) with and without magnetic field. It is evident from P-E loops of SCFO that magnetic field affects the electric polarization for all ball-milled samples and it is an indication of ME coupling in these samples at room temperature.

Symmetry Analysis of Magnetoelectric Effects in Perovskite-Based Multiferroics.

In this article, we performed symmetry analysis of perovskite-based multiferroics: bismuth ferrite (BiFeO3)-like, orthochromites (RCrO3), and Ruddlesden–Popper perovskites (Ca3Mn2O7-like), being the typical representatives of multiferroics of the trigonal, orthorhombic, and tetragonal crystal families, and we explored the effect of crystallographic distortions on magnetoelectric properties. We determined the principal order parameters for each of the considered structures and obtained their invariant combinations consistent with the particular symmetry. This approach allowed us to analyze the features of the magnetoelectric effect observed during structural phase transitions in BixR1−xFeO3 compounds and to show that the rare-earth sublattice has an impact on the linear magnetoelectric effect allowed by the symmetry of the new structure. It was shown that the magnetoelectric properties of orthochromites are attributed to the couplings between the magnetic and electric dipole moments arising near Cr3+ ions due to distortions linked with rotations and deformations of the CrO6 octahedra. For the first time, such a symmetry consideration was implemented in the analysis of the Ruddlesden–Popper structures, which demonstrates the possibility of realizing the magnetoelectric effect in the Ruddlesden–Popper phases containing magnetically active cations, and allows the estimation of the conditions required for its optimization.

Magnetoelectric coupling in Sm substituted 0.67BiFeO3- 0.33BaTiO3 ceramics

0.67(Bi1-xSmx)FeO3-0.33BaTiO3(x = 0.00 ~ 0.12) ceramics were prepared by a standard solid-state sintering method. Effects of Sm substitution on the structure, dielectric and multiferroic properties in 0.67BiFeO3-0.33BaTiO3 ceramics were investigated. Sm substitution destabilized the R3c phase, and deviated the symmetry of the present ceramics from the morphotropic phase boundary of R3c+Pm-3m to Pm-3m+P4mm. With increasing x, enhanced relaxor behaviors were observed with broaden dielectric peaks, and the slimmer P-E hysteresis loops. According to the Raman analysis and temperature dependence P-E hysteresis loops, all the compositions shown relaxor ferroelectricity with local nano-polar domains or clusters, while the domain size and distribution dominated the enhanced relaxor behaviors. Due to change of symmetry and hence the breaking of the spiral cycloidal spin structure of R3c phase, the weak ferromagnetic state with obvious macroscopic remnant magnetization was observed. Noticeable magnetoelectric (ME) coupling with linear ME voltage coefficient of αME ~ 0.55 mV/cm·Oe was achieved for x = 0.03 at room temperature. The origin of the ME properties was discussed according to the symmetry evolution.

Bi3.4Eu0.6Ti3O12/Ni0.7Cu0.3Fe2O4 films annealed under different atmosphere with enhanced magnetoelectric coupling effect

The single Bi 4-x Eu x Ti 3 O 12 and Ni 1-x Cu x Fe 2 O 4 films were prepared via spin-coating method. The composite films of the Bi 3.4 Eu 0.6 Ti 3 O 12 /Ni 0.7 Cu 0.3 Fe 2 O 4 , annealed under N 2 , air and O 2 , were also prepared via the same method. Compared with the films of Bi 4 Ti 3 O 12 , the films of the Eu-doped Bi 4 Ti 3 O 12 (Bi 4-x Eu x Ti 3 O 12 ) exhibit enhanced ferroelectricity. And when x is equal to 0.6, the films of Bi 4-x Eu x Ti 3 O 12 show optimal ferroelectricity. Compared with the undoped NiFe 2 O 4 film, in the films of Ni 1-x Cu x Fe 2 O 4 , the doping of Cu 2+ enhances ferromagnetism. And when x is equal to 0.3, the Ni 1-x Cu x Fe 2 O 4 films exhibit optimal ferromagnetism. For the composite films of Bi 3.4 Eu 0.6 Ti 3 O 12 /Ni 0.7 Cu 0.3 Fe 2 O 4 , annealing atmosphere has a significant impact on the magnetoelectric properties. In comparison with the composite films annealed under N 2 and air, the composite films annealed under O 2 exhibit optimum ferroelectricity (saturation polarization being 26.3 μC·cm −2 ), ferromagnetism (saturation magnetization being 385.6 emu·cm −3 ) and enhanced magnetoelectric coupling effect (magnetoelectric voltage coefficient being 86.4 mV·(cm·Oe) −1 ). This is beneficial for the applications in magnetoelectric functional devices.

Influence of Ni2+ Substitution on the Structure and Magnetoelectric Transport Properties of La0.67ca0.33mno3 Ceramics

Influence of Ni2+ Substitution on the Structure and Magnetoelectric Transport Properties of La0.67ca0.33mno3 Ceramics

Influence of polarity compensation on exchange bias field in LaMnO<sub>3</sub>/LaNiO<sub>3</sub> superlattices

Perovskite superlattices have received enormous attention in recent years, for they possess several new phases of quantum matter. In particular, an unexpected exchange bias effect in (111)-oriented superlattices composed of ferromagnetic LaMnO<sub>3</sub> and paramagnetic LaNiO<sub>3</sub> is observed, which has aroused broad interest. In this work, three kinds of LaMnO<sub>3</sub>/LaNiO<sub>3</sub> superlattices with (001), (110), and (111) out-of-plane orientation are fabricated by pulsed laser deposition, and also studied systemically. It is found that the superlattices are epitaxially grown on the SrTiO<sub>3</sub> substrates without strain relaxation. The superlattices have a monolayer terraced structure with a surface roughness below 0.1 nm. Electrical transport measurements reveal a Mott conducting behavior with strong localization of electrons in the superlattices. All the superlattices with different orientations exhibit exchange bias phenomenon. The field cooling and zero field cooling curves indicate that there are two different magnetic components in the superlattice in a low temperature range. Further analysis of the values of exchange field reveals that the exchange bias field is related to the orientation and polarity of the superlattices. Different superlattices form different charged planes stacked along out-of-plane orientation, leading to a polarity match/mismatch at the interface between the superlattices and substrates. The surface reconstructions that act as compensating for the polar mismatch influence the exchange bias field of the superlattices. It is observed that the intensities of the exchange field of the polar-matched superlattices are higher than those of the polar-mismatched superlattices at different temperatures. These results are helpful in further understanding the magnetoelectric transport properties in the perovskite superlattices.

Synthesis and multiferroic properties of particulate composites resulting from combined size effects of the magnetic and ferroelectric phases

The effect of grain size was not fully explored in composites containing ferroelectric and magnetic phases including the independent properties of each phase. Aiming to study the dependence of ferroic and multiferroic properties with average grain size in composites this work reports preparation method and electric, magnetic and magnetoelectric properties of particulate composites with distinct combination of grain size of each phase. A new sintering method was applied to prepare a group of samples with distinct configuration of grain size distribution. With this method it was possible to densify ceramics avoiding grain growth using spark plasma sintering. It was observed that the all ferroic and multiferroic properties were correlated with the setup of grain size of each phase in the composite, by example the dependence of magnetic properties with the electric phase grain size. Besides it was noticed that is possible to improve magnetoelectric coefficient by changing grain size of both phase, even inducing the self-biased effect by decreasing the grain size of the ferroelectric phase.

Magnetoelectric Properties of Ce2o4/Bnt–Bt0.08 Biphasic Nanocomposites, with 0-3 Connectivity, Prepared by Sol-Gel Method

Magnetoelectric Properties of Ce2o4/Bnt–Bt0.08 Biphasic Nanocomposites, with 0-3 Connectivity, Prepared by Sol-Gel Method

Magneto-electrical properties of nickel phthalocyanine thin film and its application in organic solar cells

The nickel phthalocyanine (NiPc) thin film has been explored for magneto-conductance and optoelectrical properties. The surface morphology and the opto-electrical properties of thin films of NiPc have been observed as a good candidate for the applications in polymer solar cells. The AFM images show an almost continuous surface over the studied area. The spin interaction, the disordering of the spins part, and their suitable models have been discussed by the magneto-conductance properties of the thin films. The relaxation time of carriers and traps filling phenomena with applied bias are discussed by the impedance spectroscopy. The thin films of NiPc have been introduced as a hole interface buffer layer in the standard structure of P3HT: PCBM solar cells. The power conversion efficiency (PCE) of the optimized solar cell with NiPc is ∼3.17% and the fill factor (FF) is ∼69%., these device parameters are higher (PCE increased by ∼65% and FF by ∼39%) as compared to the organic solar cells fabricated without NiPc thin films in the same batch. The improved performance of organic solar cells attributed due to lowering the series and shunt resistance.

Enhanced magneto-electric properties and magnetodielectric effect in lead-free (1-x)0.94Na0.5Bi0.5TiO3-0.06BaTiO3–x CoFe2O4 particulate composites

The lead-free magnetoelectric particulate composites (1-x)0.94Na0.5Bi0.5TiO3-0.06BaTiO3–x CoFe2O4 (where, x = 0, 0.15, 0.25, 0.35, 0.45) were synthesized by the solid-state sintering technique. The coexistence of piezoelectric 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (NBBT) and ferromagnetic CoFe2O4 (CFO) phases were confirmed by structural studies. The average crystallite size and the strain produced in the composites between the interface of different phases were estimated using Williamson-Hall method. The microstructural analysis indicates that the closely dense-packed CFO grains are distributed in the NBBT matrix. The ferroelectric nature of the composites was confirmed by the polarization versus electric field hysteresis loop and found to decrease with CFO content, which is attributed to the conducting nature of CFO. The observed values of saturation (Ms), remanent (Mr) magnetization, and magnetic moment (µB) in the composites are 28.46 emu/gm, 5.01 emu/gm and 1.13 µB, respectively for the higher CFO content. The dielectric relaxation phenomena in the composites have been observed, and the enhanced dielectric constant (ε′) is explained based on the electron hopping mechanism. All composites exhibit a relaxor nature which is described by the Vogel–Fulcher relation. The magnetoelectric coupling is estimated in the composites indirectly by measuring the relative change in the dielectric constant in the presence of the external magnetic field. The estimated values of magneto-capacitance at 1 kHz frequency for 25 and 35 mol% are ~ − 5.5 and ~ − 6%, respectively, which indicate that these materials can be useful for magneto-dielectric based devices applications.

Magnetoelectric response and internal friction in two-layer ceramic composites based on Mn0.4Zn0.6Fe2O4 magnetostrictor and PbZr0.53Ti0.47O3 piezoelectric

Magnetoelectric (ME) and anelastic properties of two-layer ceramic composites based on Mn0.4Zn0.6Fe2O4 magnetostrictor and PbZr0.53Ti0.47O3 piezoelectric at DC magnetic field strengths of 0–220 Oe, temperatures of 293–393 K, and volume fractions of PbZr0.53Ti0.47O3 of 0.40–0.67 were studied. It was found that a converse ME coupling coefficient α31 increases with the DC magnetic field strength Н1, passes through a maximum with the volume fraction ν, and decreases as temperature T rises. Dependences of α31 on Н1, ν, and T are explained using a model of effective parameters of a heterogeneous medium. The inverse correlation is revealed between α31 and an internal friction at resonant frequencies. Dependences of the internal friction on Н1, ν, and T are associated with the interaction of ferroelectric domain boundaries with crystal-lattice defects.

Behavior of magnetoelectric hysteresis and role of rare earth ions in multiferroicity in double perovskite Yb2CoMnO6

Double-perovskite multiferroics have been investigated because alternating orders of magnetic ions act as distinct magnetic origins for ferroelectricity. In Yb2CoMnO6, the frustrated antiferromagnetic order emerging at TN = 52 K induces ferroelectric polarization perpendicular to the c axis through cooperative O2− shifts via the symmetric exchange striction. In our detailed measurements of the magnetoelectric properties of single-crystalline Yb2CoMnO6, we observe full ferromagnetic-like hysteresis loops that are strongly coupled to the dielectric constant and ferroelectric polarization at various temperatures below TN. Unlike Lu2CoMnO6 with non-magnetic Lu3+ ions, we suggest the emergence of additional ferroelectric polarization along the c axis below the ordering temperature of magnetic Yb3+ ions, TYb ≈ 20 K, based on the spin structure established from recent neutron diffraction experiments. While the proposed description for additional ferroelectricity, ascribed to the symmetric exchange striction between Yb3+ and Co2+/Mn4+ magnetic moments, is clearly given, anomalies of dielectric constants along the c axis are solely observed. Our interesting findings on magnetoelectric hysteresis and the possible development of additional ferroelectricity reveal notable characteristics of double perovskites and provide essential guidance for the further examination of magnetoelectric functional properties.

Magnetoelectric composites of copper cobalt ferrite and lead zirconium titanate by screen printing method and their magnetoelectric properties

Magnetoelectric composites of copper cobalt ferrite and lead zirconium titanate by screen printing method and their magnetoelectric properties

Effect of solution concentration on magnetoelectric properties of barium ferrite ceramics

Effect of solution concentration on magnetoelectric properties of barium ferrite ceramics

Room-temperature large magnetoelectricity in a transition metal doped ferroelectric perovskite

There is increasing interest in novel magnetoelectric (ME) materials that exhibit robust ME coupling at room temperature (RT) for advanced memory, energy, spintronics, and other multifunctional device applications, by making use of the ability to control polarization with a magnetic field and/or magnetization via an electric field. Obtaining ME materials with strong ME coupling, understanding the origin, and manipulating its processing along with composition to realize large ME coefficients at RT constitute an important step in multiferroic research. To address this, we have investigated the multiferroic and ME properties of Ni-doped $\mathrm{Pb}({\mathrm{Zr}}_{0.20}{\mathrm{Ti}}_{0.80}){\mathrm{O}}_{3}$ (PZT). We find that the ferroelectric $({T}_{\mathrm{C}}\ensuremath{\sim}700\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ and weak ferromagnetic (\ensuremath{\sim}602 K) phase transitions of Ni-doped PZT are well above room temperature (RT), leading to a strong ME coupling coefficient (${\ensuremath{\alpha}}_{E,31}$) of $11.7\phantom{\rule{0.16em}{0ex}}\mathrm{mV}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{--1}\phantom{\rule{0.16em}{0ex}}{\mathrm{Oe}}^{--1}$ (${H}_{\mathrm{ac}}=1\phantom{\rule{0.16em}{0ex}}\mathrm{Oe}$ and $f=1\phantom{\rule{0.16em}{0ex}}\mathrm{kHz}$). While x-ray diffraction suggests a single-phase material, high-resolution transmission electron microscopy reveals regions with and without Ni present; thus magnetoelectric coupling between two phases is possible. First-principles calculations suggest the $(\mathrm{N}{\mathrm{i}}_{\mathrm{Pb}}{)}^{\ifmmode\times\else\texttimes\fi{}}$ defect is likely to be responsible for the experimental observed magnetism and ME coupling in Ni-doped PZT. We further demonstrate that Ni-doped PZT exhibits low loss tangent, low leakage current, large saturation polarization, and weak ferromagnetism. Ultimately, our work demonstrates that Ni-doped PZT is a cost-effective RT multiferroic with strong ME coupling.

D 5 off-centering induced ferroelectric and magnetoelectric correlations in trirutile-Fe2TeO6

We present the rare existence of d5 off-centering induced weak ferroelectric polarization and demonstrate its correlation with observed magnetoelectric (ME) properties in the G type (TN ∼ 210 K) antiferromagnet Fe2TeO6 (FTO) compound. The origin of ferroelectricity (FE) is associated with both lattice and asymmetric electron density (ED) distribution around the ion cores. ME coupling is observed in magnetic field-dependent polarization, ME voltage, and magnetostrain measurements. Short-range magnetic ordering due to intrabilayer dimeric exchange coupling via the double oxygen bridged Fe–O1–Fe pathway is proposed to play a dominating role to exhibit the negative nonlinear magnetic field-dependent ME behavior at 300 K. Interbilayer exchange via Fe–O2–Fe pathways dominantly determines the hysteretic nonlinear magnetic field-dependent ME response below TN. The observed nonlinear ME coupling signifies magnetoelasticity as manifested in the temperature and magnetic field-dependent strain measurement. Hence, the rare existence of FE and magnetoelectric coupling by d5 ion is presented in FTO.