Magnetoelectric Coupling Effect Research Articles

High-pressure single crystal growth and magnetoelectric properties of CdMn7O12

The concurrent presence of large electric polarization and strong magnetoelectric coupling is quite desirable for potential applications of multiferroics. In this paper, we report the growth of CdMn7O12 single crystals by flux method under a high pressure of 8 GPa for the first time. An antiferromagnetic (AFM) order with a polar magnetic point group is found to occur at the onset temperature of T N1 = 88 K (AFM1 phase). As a consequence, the pyroelectric current emerges at T N1 and gradually increases and reaches its maximum at T set = 63 K, at which the AFM1 phase finally settles down. Below T set, CdMn7O12 single crystal exhibits a large ferroelectric polarization up to 2640 µC m−2. Moreover, the spin-induced electric polarization can be readily tuned by applying magnetic fields, giving rise to considerable magnetoelectric coupling effects. Thus, the current CdMn7O12 single crystal acts as a rare multiferroic system where both large polarization and strong magnetoelectric coupling merge concurrently.

Magnetoelectric coupling effect in Ga3+-doped Ca3CoMn1-xGaxO6 compounds

The introduction of defects is the key method to control the multiferroic properties of one-dimensional frustration Ca3CoMnO6. In this work, we synthesized a series of Ga3+ doped Ca3CoMn1-xGaxO6 (x = 0, 0.05, 0.1, 0.2) compounds. Their crystallographic structure, magnetism as well as the dielectric properties were characterized. The XRD patterns verify the rhombohedral structure of all the samples. The Ga3+ ions have obvious inhibitory effect on the magnetic short-range order. With the substitution of Mn4+ by Ga3+, the polar nanodomains are inhibited and the diffusion index γ becomes lower. The same sign of Δε` and Δtanδ in magnetic field dependent permittivity suggests that the magnetoelectric coupling effect in Ca3CoMn1-xGaxO6 is intrinsic. For the Ca3CoMn1-xGaxO6 system, the freezing process is primarily dominated by the coupling of the polar nanodomains.

Light-Controlled Magnetoelastic Effects in Ni/BaTiO3 Heterostructures

Magnetoelastic and magnetoelectric coupling in the artificial multiferroic heterostructures facilitate valuable features for device applications such as magnetic field sensors and electric-write magnetic-read memory devices. In ferromagnetic/ferroelectric heterostructures, the intertwined physical properties can be manipulated by an external perturbation, such as an electric field, temperature, or a magnetic field. Here, we demonstrate the remote-controlled tunability of these effects under visible, coherent, and polarized light. The combined surface and bulk magnetic study of domain-correlated Ni/BaTiO3 heterostructures reveals that the system shows strong sensitivity to the light illumination via the combined effect of piezoelectricity, ferroelectric polarization, spin imbalance, magnetostriction, and magnetoelectric coupling. A well-defined ferroelastic domain structure is fully transferred from a ferroelectric substrate to the magnetostrictive layer via interface strain transfer. The visible light illumination is used to manipulate the original ferromagnetic microstructure by the light-induced domain wall motion in ferroelectric substrates and consequently the domain wall motion in the ferromagnetic layer. Our findings mimic the attractive remote-controlled ferroelectric random-access memory write and magnetic random-access memory read application scenarios, hence facilitating a perspective for room temperature spintronic device applications.

Effect of ball milling time on the magnetoelectric coupling effect of the multiferroic liquid CoFe2O4–Ba0.8Sr0.2TiO3

Effect of ball milling time on the magnetoelectric coupling effect of the multiferroic liquid CoFe2O4–Ba0.8Sr0.2TiO3

Structural, ferroelectric, ferromagnetic and magnetodielectric properties of lead free K0.5Na0.5NbO3-Ni0.5Zn0.5Fe2O4 based composites

Utilizing the conventional solid state route, the fabrication of multiferroic composites of (1-x)K0.5Na0.5NbO3-xNi0.5Zn0.5Fe2O4; x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 have been carried out in the present research work. XRD, SEM and EDS analysis shows the successful formation of composites. Whereas, P–E and M−H studies indicate their multiferroic behavior at room temperature. The dielectric properties have been carried out to know about the dielectric constant and loss in the composites. Further, the estimation of magnetoelectric coupling effect (ME) in composites has been done by measuring the magnetodielectric coefficient (MD), which is found to be highest ∼ 17 % and corresponding ME value has been calculated (88 mV/cm.Oe) for x = 0.2 composite.

Theoretical studies of sliding ferroelectricity, magnetoelectric couplings, and piezo-multiferroicity in two-dimensional magnetic materials

It has been predicted that for a series of two-dimensional (2D) materials, their van der Waals bilayers may possess sliding ferroelectricity with vertical polarizations switchable via interlayer sliding. Such intriguing ferroelectricity has been recently experimentally confirmed in a series of nonmagnetic bilayer systems like BN, MoS2, etc., while magnetic bilayers remain unexplored in those reports. In this paper we show first-principles evidence that three most prevalent 2D ferromagnetic materials, CrI3, Cr2Ge2Te6 and Fe3GeTe2, can all be entailed with sliding ferroelectricity (FE) with vertical polarizations over 0.1 pC/m in their bilayers and are thus multiferroic. In particular, Fe3GeTe2 bilayer may exhibit magnetoelectric coupling effect with a net magnetization moment of 0.01 μB per unit cell switchable upon ferroelectric switching. Moreover, it is shown to be both piezoelectric and piezomagnetic as both its vertical electric polarization and the net magnetic moment can be approximately doubled when the interlayer distance is compressed by 10%, giving rise to unprecedented “piezo-multiferroic” effect where the magnetoelectric coupling effect is intensified with reduced interlayer distance.

Tuning magnetism by electric field in MnPS3/Sc2CO2 van der Waals heterostructure

Combining a two-dimensional (2D) antiferromagnetic (AFM) material, MnPS3 and a 2D ferroelectric material, Sc2CO2, we propose 2D van der Waals (vdW) heterostructure multiferroics to realize strong magnetoelectric coupling, which is important for designing high-performance magnetoelectric devices. By using first-principles simulations, it is found that the transition from an AFM state to a ferromagnetic (FM) state of a MnPS3 layer could be realized by reversing the polarization direction of a Sc2CO2 layer. We further reveal that such strong magnetoelectric effects originate from the large inter-layer charge transfer due to the competitive interaction between the difference of the interface work functions between MnPS3 and Sc2CO2 and the strong electronegativity of the O atom interface in the Sc2CO2 layer. Our results suggest a feasible scheme for constructing 2D vdW heterostructure multiferroics with very strong inter-layer magnetoelectric coupling effect.

Transition-Layer Implantation for Improving Magnetoelectric Response in Co-fired Laminated Composite

Magnetoelectric (ME) laminated composites with strong ME coupling are becoming increasingly prevalent in the electron device field. In this paper, an enhancement of the ME coupling effect via transition-layer implantation for co-fired lead-free laminated composite (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)/(Ni0.8Zn0.2)Fe2O4 (BNKT/NZFO) was demonstrated. A transition layer composed of particulate ME composite 0.5BNKT-0.5NZFO was introduced between the BNKT piezoelectric layer and the NZFO magnetostrictive layer, effectively connecting the two-phase interface and strengthening interface stress transfer. In particular, an optimal ME voltage coefficients (αME) of 144 mV/(cm·Oe) at 1 kHz and 1.05 V/(cm·Oe) at the resonant frequency in the composite was achieved, with a layer thickness ratio (BNKT:0.5BNKT-0.5NZFO:NZFO) of 3:1:6. The static elastic model was used to determine strong interface coupling. A large magnetodielectric (MD) response of 3.95% was found under a magnetic field excitation of 4 kOe. These results demonstrate that transition-layer implantation provides a new path to enhance the ME response in co-fired laminated composite, which can play an important role in developing magnetic field-tuned electronic devices.

Magnetoelectric coupling property of 0-3 type CoFe2O4-BaTiO3 nanocomposites

The 0-3 type CoFe2O4-BaTiO3 nanocomposites have been prepared by co-precipitation sintering process in this work. The structure, dielectric, magnetic properties and magnetoelectric (ME) coupling effect of nanocomposites are studied. It finds that the 0-3 connectivity in nanocomposites results in BaTiO3 hindering the merger and growth of CoFe2O4 leading to smaller particle size (in the range 52–55 nm), creating large interface area between CoFe2O4 and BaTiO3 in composites. Creating the space charge polarization dominant thereby the dielectric constant decreased sharply with increasing frequency. Magnetization data show typical ferromagnetic behavior. Nanocomposites have strong ME coupling effect, among which C40s (CoFe2O4 content is 40 wt%) sample has a maximum ME coupling coefficient of 587.3 mV/cm∙Oe at 1.8 kHz.

Electrical and Magnetoelectric Properties of Particulate Composites and Laminated Trilayered Thick‐Film Composites

Hydraulic pressing and screen printing methods are used to create particulate magnetoelectric composites and laminated trilayered thick‐film composites. X‐ray diffraction studies reveal the presence of cubic spinel and tetragonal perovskite structures for individual powders of ferrite CuFe2O4 and ferroelectric‐phase PbZr0.58Ti0.42O3. The dielectric constant of particulate composites decreases with increasing frequency around 1 MHz and beyond that frequency, a saturation state is attained. However, for laminated films, the dielectric constant decreases up to 1 MHz and then increases. The maximum dielectric constant at low frequency for particulate CuFe2O4/PZT composites is around 72.2, whereas for laminated CuFe2O4/PZT/CuFe2O4 composites it is 4.97 and for PZT/CuFe2O4/PZT composites is 5.24. Loss tangent exhibits the same trend as dielectric constant with frequency, which is explained by space charge polarization and is consistent with Koop's phenomenological theory. The dielectric constant's variation with temperature describes the contribution of electric dipoles to polarization and both composites exhibit absorption peaks. The semiconducting nature of both particulate and laminated composites can be seen in the DC resistivity graph with frequency and as frequency increases, DC resistivity decreases for both composites, which is explained by the small polaron‐hopping phenomenon. The magnetoelectric coupling effect for particulate composites (44 mV Oe−1cm−1) is also found to be small when compared to laminated trilayered composites (CuFe2O4/PZT/CuFe2O4—105 mV Oe−1cm−1 and PZT/CuFe2O4/PZT—68 mV Oe−1cm−1).

Ferroelectrically tunable magnetic skyrmions in two-dimensional multiferroics.

Magnetic skyrmions are topologically protected entities that are promising for information storage and processing. Currently, an essential challenge for future advances of skyrmionic devices lies in achieving effective control of skyrmion properties. Here, through first-principles and Monte-Carlo simulations, we report the identification of nontrivial topological magnetism in two-dimensional multiferroics of Co2NF2. Because of ferroelectricity, monolayer Co2NF2 exhibits a large Dzyaloshinskii-Moriya interaction. This together with exchange interaction can stabilize magnetic skyrmions with the size of sub-10 nm under a moderate magnetic field. Importantly, arising from the magnetoelectric coupling effect, the chirality of magnetic skyrmions is ferroelectrically tunable, producing the four-fold degenerate skyrmions. When interfacing with monolayer MoSe2, the creation and annihilation of magnetic skyrmions, as well as phase transition between skyrmion and skyrmion lattice, can be realized in a ferroelectrically controllable fashion. A dimensionless parameter κ' is further proposed as the criterion for stabilizing magnetic skyrmions in such multiferroic lattices. Our work greatly enriches the two-dimensional skyrmionics and multiferroics research.

Spin-splitting and switchable half-metallicity in a van der Waals multiferroic CuBiP2Se6/GdClBr heterojunction.

Multiferroic van der Waals (vdW) heterojunctions have a strong and nonvolatile magnetoelectric coupling effect, which is of great significance in spintronic devices. The electronic structure and magnetic properties of a GdClBr/CuBiP2Se6 vdW multiferroic heterojunction have been calculated using first-principles methods. Due to the spin-up charge transfer and Zeeman field, the ferroelectric CuBiP2Se6 exhibits spin splitting at the gamma point. It is found that the electronic structure and magnetic properties of the GdClBr/CuBiP2Se6 vdW multiferroic heterojunction have been significantly modulated by the electric polarization of CuBiP2Se6. During the reversal of the ferroelectric polarization of CuBiP2Se6, the ferromagnetic GdClBr monolayer transforms from a semiconductor to a half-metal. Meanwhile, in both upward and downward ferroelectric polarization, the GdClBr/CuBiP2Se6 heterojunction exhibits perpendicular magnetic anisotropy with a Curie temperature of 239 K. As the strain changes from -6% to 6%, the band structure of GdClBr shifts upward, and the band structure of CuBiP2Se6 shifts downward. Compressive strain can increase the Curie temperature of the GdClBr/CuBiP2Se6 heterojunction. The magnetic anisotropy of heterojunctions highly depends on biaxial strain, where the perpendicular (in-plane) magnetic anisotropy increases with the increased compressive (tensile) strain. The vdW multiferroic GdClBr/CuBiP2Se6 heterojunction has potential applications in spintronic devices.

Magnetic field driven catalysis of multiferroic magnetoelectric nanocomposites

Magnetic field as a booster for catalytic reactions has been widely studied in the past few decades. Recently, multiferroic materials with intriguing magnetoelectric coupling effects have been emerging as a new type of catalyst, providing a unique opportunity for magnetically-driven catalytic reactions in a variety of fields, including clean energy, environmental and biomedical applications. In this review, we describe this entirely new catalysis phenomenon observed in multiferroic magnetoelectric composite materials, aiming at giving an in-depth understanding of magnetically-driven catalysis processes based on the direct magnetoelectric-catalytic effect. Moreover, the latest progress in catalytic applications of magnetoelectric nanocomposite nanomaterials is comprehensively summarized. Finally, the challenges and future perspectives for the design and application of high-efficient magneto-multiferroic catalysts are discussed.

Dimerization Triggered Magnetoelectric Coupling Effect and Magnetic Anisotropy in Organic Ternary Crystals.

Developing a new universal strategy to design all organic ferromagnets or multiferroics with satisfactory properties always remains challenging. In this work, ternary charge transfer crystals are fabricated to realize organic multiferroic magnetoelectric coupling effect. Through incorporating the third component into binary crystals, a dimerization between neighbor donor and acceptor is induced to form a lattice symmetry breaking, where a nonpolar to polar phase transition is ensuing to lead to a dipolar polarization. Magnetic field can effectively tune the dipolar polarization to present a magnetoelectric coupling effect. Moreover, the introduction of the third component can result in a rearrangement in molecular configuration to modify the electron-phonon interaction. As a result, anisotropic magnetism is observed due to anisotropic electron-phonon coupling in ternary crystals. Overall, this study forecasts that incorporating an appropriate third component is a potential method for designing all organic multiferroics.

Two-Dimensional Multiferroics with Intrinsic Magnetoelectric Coupling in A-Site Ordered Perovskite Monolayers

The magnetoelectric coupling effect in multiferroics provides a route to realize the control of magnetism by electric field. Here, we demonstrate the coexistence and coupling of ferroelectricity and ferromagnetism in designed A-site ordered perovskite oxide monolayers by combining symmetry analysis and first-principles calculation. These monolayers all exhibit a layered ordering and tilt distortion, and some of them exhibit rotation or Jahn-Teller distortion simultaneously, leading to the emergence of in-plane ferroelectricity. The Mn-based monolayers exhibit robust ferromagnetism, while some monolayers tend to form E-type spin order due to the splitting of the nearest-neighbor exchange interactions. Whether polarization reversal can lead to magnetization reversal depends on the mode of ferroelectric switching, that is, only the ferroelectric switching that reversing the tilt distortion can lead to magnetization reversal. This work demonstrates the feasibility of controlling the direction of magnetization by electric field in the monolayer limit of perovskites.

Magnetoelectric‐Field Electrodynamics: Search for Magnetoelectric Point Scatterers

AbstractResonant scattering of electromagnetic (EM) waves by small particles is considered as one of the basic problems in metamaterial science. At present, special subwavelength resonators are considered as structural elements in chiral and bianisotropic metamaterials. There is a general consensus that these small scatterers behave like “artificial atoms” with strong electrical and magnetic responses and an interconnection between these responses. However, the observed effect of magnetoelectric (ME) coupling in these meta‐atoms is not associated with the near‐field manipulation properties caused by intrinsic magnetoelectricity. This arises the question whether ME point scatterers of EM radiation really exist. In this paper, we show that there are mesoscopic structures with electric and magnetic dipole‐carrying excitations that behave like point scatterers with their inherent magnetoelectricity. In such subwavelength resonators, coherent oscillations of the electric polarization and magnetization can be considered as quasistatic oscillations described by electrostatic (ES) and magnetostatic (MS) scalar wave functions. The ME resonance effect arises from the coupling of two, ES and MS, oscillations. The near fields of these resonators, called the ME near fields, are characterized by simultaneous violation of time reversal and inversion symmetry. In study of ME fields and EM problems associated with these fields, we put forward the concept of ME‐field electrodynamics.

In a search for effective giant magnetoelectric coupling: Magnetically induced elastic resonance in Ni-Mn-Ga/P(VDF-TrFE) composites

Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) is a piezoelectric polymer suitable for applications in electromechanical and magnetoelectric (ME) systems. Ni-Mn-Ga alloys exhibit a giant magnetoelastic response related to their structural transformations of martensitic type, accompanied by noticeable volume changes. Together, in a thin film composite containing an ensemble of Ni-Mn-Ga particles (10 wt.%) distributed in the P(VDF-TrFE) piezopolymer, they ensure an unprecedented resonance amplification of the ME effect. Thus, a giant value of ME coefficient of 6.05 V·cm−1· Oe−1 under AC magnetic drive field of 0.2 Oe and DC bias field of 1300 Oe is experimentally observed and discussed. The physical mechanism of the proposed ME response amplification has been explained theoretically through the volume magnetostriction of the magnetostrictive particles and resonant elastic oscillation of the piezoelectric polymer matrix.

Electric-field control of magnetization reversal at room temperature in SmFeO3 single-phase multiferroic thin film

Rare-earth orthoferrite SmFeO3 (SFO) is a promising single-phase multiferroic material because of simultaneous coexistence of magnetic and ferroelectric orders at room temperature (RT). However, the spin structures within this bulk material are antiferromagnetic arrangements, and the magnetoelectric (ME) coupling effect is weak. Thus, the realization of electric control of magnetization reversal at RT remains challenging. In this work, SFO thin films with different thicknesses of 30 nm, 60 nm and 90 nm were constructed onto LaNiO3 (LNO)-buffered LaAlO3 (LAO) substrates by pulsed laser deposition (PLD) method. The X-ray diffraction (XRD) θ-2θ scans and reflection high-energy electron diffraction (RHEED) patterns demonstrate the SFO is perfect growth along the LAO (00 l) direction. Besides, the magnetic measurement results indicate that all the thin films are induced obvious RT ferromagnetism by compressive strain of substrates. More importantly, when providing a pair of opposite polarization voltages of± 2.5 V for the 90 nm thin film, the ferroelectric and induced ferromagnetic domains at the same local area can realize synchronous reversal, which shows that the SFO thin film under compressive strain is a rare ferromagnetic-based ME multiferroic material at RT. This kind of material will produce wide application prospect in future electric-write magnetic-read high-density memories and other spintronics devices.

Significantly enhanced hybrid improper ferroelectricity of Ca3Ti2O7 ceramics by the oxygen vacancy engineering

Ca3Ti2O7 materials with hybrid improper ferroelectricity call tremendous interest due to their great potential in designing novel room-temperature single-phase multiferroics with a strong magnetoelectric coupling effect. However, achieving Ca3Ti2O7-based ceramics with superior room-temperature ferroelectricity remains a crucial challenge. Herein, Ca3Ti2O7 ceramics were prepared by a tartaric acid sol–gel method and sintered in air and oxygen atmospheres, respectively. It was found that the long-time high-temperature sintering in air could lead to the formation of CaTiO3/Ca3Ti2O7/CaTiO3 sandwich structure, and oxygen-enriched sintering could effectively avoid the formation of CaTiO3 phase on the surface. The superior hybrid improper ferroelectricity is attained in Ca3Ti2O7 ceramics sintered in oxygen atmosphere with a higher remnant polarization (3.63 μC/cm2) and lower coercive electric field (72.6 kV/cm) obtained by positive-up and negative-down method, which is better than the ceramic sample sintered in air. The significantly better ferroelectricity is benefited from the synergistic effects of its larger distortion of oxygen octahedron, larger grain size, and lower oxygen vacancy concentration. Due to its low leakage current density, Ca3Ti2O7 ceramics sintered in oxygen atmosphere exhibit the remanent polarization as high as 7.40 μC/cm2 under the conditions of 1 Hz and 200 kV/cm obtained by dynamic hysteresis measurement mode. Furthermore, there are obvious stripe ferroelectric domains, which provide direct evidence for the excellent hybrid improper ferroelectricity of Ca3Ti2O7 ceramics. These findings demonstrate that the oxygen vacancy engineering is an effective strategy to improve hybrid improper ferroelectricity of Ca3Ti2O7 materials.

Tunable magnetic behavior, conductivity and valley polarization in two-dimensional YMnO3/2H-VS2 multiferroic heterostructures

Manipulation of spin-valleys plays a key role in spintronics and valleytronics. The magnetoelectric coupling effect in the two-dimensional (2D) ferroelectricity/ferromagnetism heterostructures offers a feasible way to achieve the modulation of magnetic properties and valley degrees of freedom. In this work, the electronic structure, magnetism and valley polarization of YMnO 3 /2H-VS 2 multiferroic heterostructures are investigated in detail by first-principles calculations. The results show that the ferromagnetism , valley polarization and conductivity of 2H-VS 2 layer can be largely altered by the YMnO 3 substrate with different terminations. The valley polarization can achieve a maximum modulation of 112.5 meV for the YMnO 3 /2H-VS 2 heterostructure with MnO-termination when the ferroelectric polarization is reversed. On the other hand, the direction of magnetic moment of V atom in the 2H-VS 2 layer can be effectively adjusted in the O2- and Y-terminated configurations by altering the ferroelectric polarization, which can be attributed to the magnetic interaction between the ferromagnetic 2H-VS 2 and ferroelectric YMnO 3 . Compared with the case of isolated 2H-VS 2 monolayer, 2H-VS 2 exhibits p-type doping character in O- and Y-terminated configurations. The valley and direct bandgap semiconductor properties of 2H-VS 2 monolayer are preserved for all configurations. Moreover, the O–S distance can be considered as a main factor for regulating the valley polarization by affecting orbital hybridization. These results exhibit new coupling effects between ferromagnetism, ferroelectronics and ferrovalley by the electrical control of spin-valleys behaviors, which provides a new platform for developing nonvolatile spintronic and valleytronic devices. • Magnetism and valley polarization of YMnO 3 /2H-VS 2 multiferroic heterostructures are investigated. • Valley polarization of 2H-VS 2 is largely altered by YMnO 3 substrate with different terminations. • Valley polarization achieves a maximum modulation of 112.5 meV with MnO-termination. • The O–S distance can be considered as a main factor for regulating the valley polarization.