Magnetoelectric Coefficient Research Articles

A flexible magnetic detector based on transferred ferroelectric/ferromagnetic thin film heterostructure

A flexible magnetic detector based on ferroelectric/ferromagnetic (PZT/Metglas) thin film heterostructure is developed by using etching and transferring technique. The transferred PZT film still exhibits (001)-oriented or very highly textured structure with good ferroelectricity (P r = 50 μC cm−2 and E c = 150 kV cm−1). Magnetoelectric (ME) voltage coefficient of the PZT/Metglas film heterostructure approaches 5.1 V cm−1 Oe at resonance frequency (57.5 kHz). The flexible detector has a sensitivity of AC 0.3 nT and DC 1 Oe with high stability for magnetic field detection. Our demonstration provides a viable approach for realizing ME thin film transfer technology, which is of great significance for future applications on flexible magnetic detectors.

Enhanced ferroelectric and magnetic properties of the 0–3 type BiFeO3-BaTiO3/BaFe12O19 composite multiferroic material

The 0–3 type (1-x)(0.75BiFeO3-0.25BaTiO3)/xBaFe12O19 (BFO-BTO/BaM) multiferroic composites were successfully prepared by a solid-state reaction sintering process. The coexistence of perovskite BFO-BTO phase and hexagonal BaM phase was confirmed for all BFO-BTO/BaM composites. Due to the large leakage current, the breakdown electric field decreased with increasing BaM content. Nevertheless, the ferroelectric properties of the composite ceramics have also been significantly improved, mainly as the increase of remanent polarization and the decrease of coercive field, where Pr = 19.79 μC/cm2, Ec = 30 kV/cm at x = 0.075. Meanwhile, the magnetic properties of BFO-BTO phase were enhanced, and the remanent magnetization linearly increased with increasing BaM content. The single domain magnetic structure was obtained for all BFO-BTO/BaM composite ceramics, and the magnetic properties changed after electric poling, which indicated the electric field controlled magnetic properties. The electric-controlled magnetic behavior was attributed to the structural phase transition. The magnetoelectric coupling coefficient αME of the composite material has been improved, with a maximum value of 0.61 mV/cm.Oe. Thus, the BFO-BTO/BaM magneto-electric composite system is a promising multiferroic system in information technology and sensing fields.

Enhanced magnetoelectric coupling performance in CoFe2O4 @BaTiO3 multiferroic liquid by tuning the CoFe2O4 morphology

Multiferroic materials are identified as a newly emerging area of research because of their obvious magnetoelectric effects between ferroelectric and ferromagnetic orders. This paper uses the ball milling method to prepare CoFe2O4 @BaTiO3 (CFO@BTO) multiferroic liquids with different CoFe2O4 (CFO) particle morphologies. The settling stability and magnetoelectric properties of the CFO@BTO multiferroic liquids with different CFO particle morphologies have been systematically studied. XRD analysis confirmed that the crystal structure of the powders was consistent with that of standard cards, and the CFO powders exhibited irregular spherical shapes, well-dispersed rectangular shapes, and uniform nanowires. TEM images revealed a core-shell structure of the formed particles. The study found that as the CFO particle morphology changed from spherical to rectangular and then to nanowire, both the residual magnetization intensity (Mr) and saturation magnetization intensity (Ms) of both CFO powder and CFO@BTO composite powder increased gradually. The settling rate of the multiferroic liquids with spherical CFO morphology was observed to be 4.6% with good settling stability after resting for 48 h. The dielectric constant and dielectric loss showed similar trends in the presence and absence of magnetic fields. With the change in CFO particle morphology, the maximum polarization strength (Pmax), residual polarization strength (Pr), and coercivity field strength (Ec) of the multiferroic liquids gradually increased. The magnetoelectric coupling coefficient of the multiferroic liquids was found to be the largest when the CFO morphology was rectangular, measuring 23.93 V/(cm·Oe). The study provides insights into improving the magnetoelectric coupling effect of multiferroic materials and opens up new possibilities for further research in this area.

Detection of inhomogeneous magnetic fields using magnetoelectric composites

Magnetoelectric (ME) composites have a wide range of possible applications, especially as room-temperature sensors of weak magnetic fields in magnetocardiography and magnetoencephalography medical diagnostic equipment. In most works on ME composites, structures are tested in uniform magnetic fields; however, for practical application, detailed knowledge of their behaviour in inhomogeneous magnetic fields (IMFs) is necessary. In this work, we measured IMFs with radial symmetry produced by alternate currents (AC) passing through an individual thin wire upon different placements of an ME sensor. An ME self-biased b-LN/Ni/Metglas structure with a sensitivity to the magnetic field of 120 V/T was created for IMF detection. The necessity of an external biasing magnetic field was avoided by the inclusion of a nickel layer having remanent magnetization. The ME composite shows a non-zero ME coefficient of 0.24 V/(cm · Oe) in the absence of an external DC magnetic field. It is shown that the output voltage amplitude from the ME composite, which is located in an AC IMF, is dependent on the relative position of the investigated sample and magnetic field lines. Maximum ME signal is obtained when the long side of the ME sample is perpendicular to the wire, and the symmetry plane which divides the long side into two similar pieces contains the wire axis. In the frequency range from 400 Hz to 1000 Hz in the absence of vibrational and other noises, the detection limit amounts to (2 ± 0.4) nT/Hz1/2.

Nonlinear magnetoelectric effect in a ring composite heterostructure

Objectives. The relevance of the study of magnetoelectric (ME) effect in ring ferromagnetic–piezoelectric heterostructures is due to the possibility of creating various ME devices having improved characteristics. A detailed investigation of the nonlinear ME effect in a ring composite heterostructure based on lead zirconate titanate (PZT) piezoceramics and Metglas® amorphous ferromagnetic (FM) alloy under circular magnetization is presented.Methods. The ME effect was measured by the low-frequency magnetic field modulation method. Excitation alternating- and constant magnetic bias fields were created using toroidal coils wound on a ring heterostructure for circular magnetization of the FM layer.Results. When excited with circular magnetic fields in a non-resonant mode, the ME ring heterostructure generates a nonlinear ME voltage of higher harmonics. The field and amplitude dependencies of the first three ME voltage harmonics were investigated. ME coefficients were obtained for the linear ME effect α(1) = 5.2 mV/(Oe·cm), the nonlinear ME effect α(2) = 6 mV/(Oe2·cm), and α(3) = 0.15 mV/(Oe3·cm) at an excitation magnetic field frequency f = 1 kHz. The maximum amplitudes of the 1st and 3rd harmonics were observed at a constant bias magnetic field H ~ 7 Oe, which is almost two times smaller than in planar PZT–Metglas® heterostructures.Conclusions. A nonlinear ME effect was observed and investigated in a ring heterostructure based on PZT piezoceramics and Metglas® amorphous FM alloy. Due to the absence of demagnetization during circular magnetization of the closed FM layer, nonlinear ME effects are detected at significantly lower amplitudes of the exciting alternating and constant bias magnetic fields as compared to planar heterostructures. The investigated ring heterostructures are of potential use in the creation of frequency multipliers.

Magnetoelectric Core–Shell Nanoparticle–Based Wearable Hybrid Energy Harvesters for Biomedical Applications

In this work, a novel barium titanate–coated cobalt ferrite core–shell magnetoelectric nanoparticle and poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate–based wearable energy‐harvesting patch for wireless power‐transfer applications are proposed. The developed flexible patch has unique ease of fabrication and high‐efficiency energy conversion capability from the magnetic field and mechanical motion to the electric field as compared to bulk or thin‐film‐based devices. This unique power‐transfer capability of this device is achieved due to the crystalline nature of fabricated nanoparticles, which is confirmed using X‐ray diffraction and high‐resolution transmission electron microscopy. This wearable patch can generate a high voltage of 560 mV when exposed to a 40 μT alternating magnetic field at the resonance frequency of 48.6 kHz. The hybrid mode of electric power generation is achieved by coupling bodily motion with the remotely applied alternating magnetic field (40 μT), which results in the generation of a higher electric potential of 860 mV and maximum power density of 0.458 mW cm−3 across a 10 kΩ load. The maximum magnetoelectric coefficient is recorded as 1300 mV cm−1 Oe−1. The flexible nature and hybrid operation of the proposed device make it an efficient alternative for powering a wide range of wearable medical electronic devices.

Improved room-temperature magnetoelectric coupling properties for multiferroic Z-type hexaferrites

Here we present the results of a systematic investigation of the effect of Ba substitution on the spiral magnetic structure and magnetoelectric effect in polycrystalline BaxSr3−xCo2Fe24O41 (x = 0.0, 0.1, 0.3, 0.5, and 0.7). The magnetoelectric coupling coefficient was improved from 455 ps/m (x = 0.0) to 624 ps/m (x = 0.3). Furthermore, the magnetic field range at which the magnetoelectric signal appears extended from 0-∼0.4 T (x = 0.0) to 0-∼0.9 T (x = 0.5), demonstrating that the transverse conical spin structure was significantly strengthened by Ba substitution. These improvements are attributed to the decrease of Fe-O-Fe bond angle near the L and S blocks boundary, the reduction of cone angle in the transverse conical spin structure, and the change in the distribution of magnetic Co ions caused by the substitution of large Ba ions for small Sr ions. In general, we achieved the improved magnetoelectric coupling strength in polycrystalline Z-type hexaferrite for the first time.

Investigation of the Structural, Dielectric, Magnetic, and Magnetoelectric Properties of Nd-Substituted Sr3Co2Fe24O41 Z-Hexaferrite

The Neodymium (Nd) substituted Sr-based Z-Hexaferrites having composition Sr3-xNdxCo2Fe24O41 (x = 0, 0.15, 0.30 and 0.45) corresponding to pristine, 5, 10 and 15% substitution were prepared using solid-state reaction method in pre-optimized rare Earth metal solubility range (x ≤ 0.45) and labeled as SCFO, SNCFO5, SNCFO10 and SNCFO15, respectively. X-ray diffractometer and Scanning Electron Microscopy (SEM) were utilized to investigate the prepared samples’ structure and grain morphology. The X-ray diffraction (XRD) patterns confirmed Z-hexaferrite formation with adequate phase purity. Dielectric measurements exhibited a relaxation-type, frequency-dependent, and thermally activated dielectric response across all prepared samples. In Nd substituted SCFO, the obtained value of coercivity (Hc) ranges from 52.2–68.45 oersted, confirming a soft magnetic behavior. Magnetoelectric coupling coefficient(α) recorded at room temperature has a maximum value of 0.2133 mV cm−1Oe−1 for the pristine sample and this value of α varies with Nd substitution for all prepared samples.

Response of DC biased magnetoelectric coupling in 0–3 type particulate lanthanum modified PZT-CFO composites

Magnetoelectric effect (ME) has been investigated in particulate ferroelectric (FE)-ferrimagnetic (FM) composites in the present work. The composition of ceramic composites has been tailored in terms of (1 - x) Pb0.4La0.6Zr0.6Ti0.4O3 (PLZT) – (x)CoFe2O4 (CFO) [x = 0, 0.2, 0.4, 0.6 and 1] in order to observe the magnetoelectric coupling. The FE-FM (PLZT-CFO) composites prepared using solid state route were investigated in terms of structural, morphological, dielectric, ferroelectric and magnetic properties. Well crystallized PLZT-CFO composites were observed with binary rhombohedral (R3m) and cubic (Fd3m) phase of PLZT and CFO, respectively, along with well-defined grains for both parent phases. The appearance of relaxor behaviour in prepared composites was revealed from temperature dependent dielectric study. The saturation (Ps) and remnant (Pr) polarizations were observed to be vary from 45µC/cm2 to 10µC/cm2 and 36µC/cm2 to 7 µC/cm2, with the increment in the CFO content from 0 % to 80 %, respectively. The emergence of long-range ferromagnetic ordering is revealed from M-H curves. It is evident from magnetization and polarization studies that each composite exhibits exceptional sensitivity to both the electric and magnetic fields. The magnetoelectric coefficient, is found to be initially rise with x and achieved maximal value of 450 µV/cm.Oe for 40 % CFO content. The obtained results indicate that almost equal number of weight proportion is required for achieving maximum strain transfer between FE-FM phases which is beneficial for future FE-FERAM devices. It is also perceptible that these novel composites may provide knowledge pathway for development of ME multifunctional device miniaturization.

Magnetoelectric nanoparticles shape modulates their electrical output.

Core-shell magnetoelectric nanoparticles (MENPs) have recently gained popularity thanks to their capability in inducing a local electric polarization upon an applied magnetic field and vice versa. This work estimates the magnetoelectrical behavior, in terms of magnetoelectric coupling coefficient (αME), via finite element analysis of MENPs with different shapes under either static (DC bias) and time-variant (AC bias) external magnetic fields. With this approach, the dependence of the magnetoelectrical performance on the MENPs geometrical features can be directly derived. Results show that MENPs with a more elongated morphology exhibits a superior αME if compared with spherical nanoparticles of similar volume, under both stimulation conditions analyzed. This response is due to the presence of a larger surface area at the interface between the magnetostrictive core and piezoelectric shell, and to the MENP geometrical orientation along the direction of the magnetic field. These findings pave a new way for the design of novel high-aspect ratio magnetic nanostructures with an improved magnetoelectric behaviour.

Investigation of the magnetoelectric properties of Bi0.9La0.1Fe0.9Mn0.1O3/La0.8Sr0.2MnO3 bilayer: Monte Carlo simulation

In the present work, the magnetic, ferroelectric and magnetoelectric properties of the bilayer composite Bi0.9La0.1Fe0.9Mn0.1O3/La0.8Sr0.2MnO3 (BFO-LM/LSMO) have been studied using Monte Carlo simulation in the framework of the Heisenberg model. The magnetoelectric properties of BFO-LM/LSMO bilayer films with different stacking modes were predicted and analyzed. Furthermore, the effect of interfacial coupling on the magnetoelectric properties was analyzed, and a maximum magnetoelectric voltage coefficient of 195.5 mV/(cm.Oe) was obtained in the BFO-LM/LSMO bilayer films with BL/Mn-interface. The magnetic coupling at the FM/Mn interface provides a novel ferromagnetic state localized at the interface and an improvement in the magnetic properties. The obtained results make BFO-LM/LSMO films a promising material for advanced magnetoelectric applications.

Structural, magnetic and ferroelectric properties of magnetoelectrically coupled xBa0.95Sr0.05TiO3-(1–x)BiFe0.90Sm0.10O3 ceramics

ABSTRACT The standard solid state reaction method was followed to synthesize the polycrystalline xBa0.95Sr0.05TiO3-(1–x)BiFe0.9Sm0.1O3 [xBST-(1–x)BFSmO, x = 0–0.35] ceramics. The XRD pattern revealed a structural transition of the prepared ceramics from rhombohedral to cubic symmetry. The mean grain size was estimated in the micrometer range, with values ranging from 0.40 to 1.95 μm. The maximum real part of the complex initial permeability of 28.26 was noticed for x = 0.30 multiferroic ceramics. The highest remanent magnetization determined for the x = 0.30 sample was 3.4 10−2 emu/g. For the sample with x = 0.35 the maximum recorded dielectric constant was found to be 677 at 103 Hz. A small value of dielectric loss (<5%) was observed. The compound exhibited significant remanent polarization and a reduction in the leakage current. In addition, the investigated materials comprise large magnetoelectric coefficients and the optimum magnetoelectric coefficient of 0.662 mV.cm−1.Oe−1was obtained for the x = 0.30 composition.

Structural, magnetic, dielectric, magneto-electric and ferroelectric properties of BaTiO3- NiFe2O4 multiferroics

Multiferroics having composition yNiFe2O4 - (1-y) BaTiO3(y = 0.10, 0.30 and 0.50) have been prepared through the solid-state reaction route. These samples constitute NiFe2O4 as the ferromagnetic phase and BaTiO3as the ferroelectric phase. The X-ray diffraction (XRD) has been carried out to investigate the crystal structure formation and phase purity of the prepared ceramic samples. Rietveld refinement of XRD patterns confirm the presence of cubic (Fd3m) and tetragonal (P4mm) symmetries in all the samples. The effect of ferrite (NFO) concentration on magnetic, dielectric, ME coefficient and ferroelectric properties of samples has been studied further. The recorded M-H loops at room temperature, reflects the ferromagnetic nature of all samples. These hysteresis loops are fitted by LAS (law of approach to saturation), and the values of various magnetic parameters are evaluated. A gradual enhancement in magnetic parameters is noticed with an increased in NFO concentration. Variations of dielectric constant (ɛ') and loss tangent (tan δ) as a function of frequency as well as of temperature at various selected frequencies (10 kHz, 100 kHz, 500 kHz, and 1 MHz) have been studied. The highest value of magnetoelectric (ME) response has been observed for thesample0.10NiFe2O4-0.90BaTiO3. P-E loops show an enhancement in both the coercive field and the remnant polarization with an increment in ferrite content at room temperature.

Flexible magnetoelectric sensor and nonvolatile memory based on magnetization-graded Ni/FSMA/PMN-PT multiferroic heterostructure

Flexible multiferroic heterostructures are promising to unveil technological developments in wearable magnetic field sensing, nonvolatile memory, soft robotics, and portable energy harvesters. Here, we report an enhanced and a zero-biased magnetoelectric (ME) effect in flexible, cost-effective, and room temperature sensitive Ni/FSMA/PMN-PT magnetization-graded ME heterostructure. Flexible Ni foil with −q (piezomagnetic coefficient) and the ferromagnetic shape memory alloy (FSMA; Ni-Mn-In) layer with +q offers the desired q-grading. The temperature-dependent dielectric behavior shows an anomaly in the martensite transformation regime of the FSMA layer. The Ni/FSMA/PMN-PT ME heterostructure exhibits noteworthy ME output of ∼3.7 V/cm Oe, significantly higher than Ni/PMN-PT (∼1 V/cm Oe). The q-grading-induced bending moment impedes the asymmetry-related flexural strain and strengthens the ME interaction. The zero-bias ME output of ∼0.4 V/cm Oe is ascribed to the interaction between q-grading-induced transverse magnetization and AC magnetic field. Ni/Ni-Mn-In/PMN-PT ME heterostructure displays excellent magnetic field sensing parameters: correlation coefficient, sensitivity, inaccuracy, and hysteresis of 0.99916, ∼0.74 mV/Oe, 1.5% full-scale output (FSO), and 1.8% FSO, respectively. The reversible and repeatable nonvolatile switching of the ME coefficient obtained with positive and negative electric fields is useful for next-generation memory devices. The flexible ME heterostructure shows no degradation in performance up to 1500 bending cycles. Such Ni/FSMA/PMN-PT based ME heterostructures are propitious for multifunctional flexible magnetic field sensors and nonvolatile memory applications.

Magnetoelectric response in laminated BaFe12O19/Pb(Zr,Ti)O3 composites

The magnetoelectric (ME) response of laminated composites consisting of BaFe12O19 and Pb(Zr,Ti)O3 ceramics is systematically investigated. A butterfly-shaped curve of a magnetoelectric coefficient emerges in both three-layer and multilayer composites. We show that the appearance of a 7 ppm residual strain in the BaFe12O19 layer after magnetization is the main reason for this special curve. We also observe the self-biasing effect of the composites and a maximum ME response from 0.6 to 5 mV/(Oe cm) in laminated composites with magnetic and ferroelectric layers of different thicknesses that can be measured at a zero-bias magnetic field. The repeatable and stable maximum and minimum values of the magnetoelectric coefficient can be obtained under periodically applied biasing magnetic fields, which is important for a practical device application. An electric-field control of ferromagnetism, evidenced by a 17%–19% enhancement in the magnetization of the BaFe12O19 layer after Pb(Zr,Ti)O3 is polarized, is observed in the composites, implying potential applications in memory devices for the composites. Our work indicates that both magnetic field-controlled polarization and electric-field-controlled magnetization exist in BaFe12O19/Pb(Zr,Ti)O3 laminated composites.

Low-Frequency Resonant Magnetoelectric Effects in Layered Heterostructures Antiferromagnet-Piezoelectric

Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The parameters of ME sensors are determined by characteristics of the magnetic constituent. In this work, the low-frequency ME effects in heterostructures comprising a layer of antiferromagnetic hematite α-Fe2O3 crystal with easy-plane anisotropy and a piezoelectric layer are studied. The effects arise due to a combination of magnetostriction and piezoelectricity because of mechanical coupling of the layers. The field dependences of magnetization and magnetostriction of the hematite crystal are measured. The resonant ME effects in the hematite-piezopolymer and hematite-piezoceramic structures are studied. The strong coupling between magnetic and acoustic subsystems of hematite results in a tuning of the acoustic resonance frequency by the magnetic field. For the hematite layer, the frequency tuning was found to be ~37% with an increase in the bias field up to 600 Oe. For the hematite-PVDF heterostructure, the frequency tuning reached ~24% and the ME coefficient was 58 mV/(Oe∙cm). For the hematite-piezoceramic heterostructure, the frequency tuning was ~4.4% and the ME coefficient 4.8 V/(Oe∙cm). Efficient generation of the second voltage harmonic in the hematite-piezoceramic heterostructure was observed.

Multiferroic CoFe2O4–Ba0.95Ca0.05Ti0.89Sn0.11O3 Core–Shell Nanofibers for Magnetic Field Sensor Applications

Multiferroic materials with coexisting of at least two ferroic orders (ferromagnetic, ferroelectric, or ferroelastic) have recently attracted the interest of researchers due to their potential applications as multifunctional devices. Herein, we report the synthesis and detailed characterization of the multiferroic CoFe2O4–Ba0.95Ca0.05Ti0.89Sn0.11O3 core–shell nanofibers (CFO@BCTSn NFs) prepared by a sol–gel coaxial electrospinning technique. The scanning and transmission electron microscopes were used to check nanofibers’ core–shell structure/configuration, with fiber diameters ranging from 150 to 250 nm. The X-ray diffraction analysis confirms the presence of both the spinel structure of the CFO and the perovskite structure of the BCTSn. Piezoresponse force microscopy and magnetic hysteresis were used to confirm the multiferroicity of CFO@BCTSn NFs. Notably, the maximum magnetization and remanent magnetization of NFs are found to be 11.63 emu g–1 and 1.43 emu g–1, respectively. Meanwhile, the maximum piezoelectric response d33eff is around 6 pm V–1. The magnetoelectric (ME) coefficient obtained for the CFO@BCTSn NFs is 346 mV cm–1 Oe–1 at the field of 10 kG. These findings may lead to development of nanoscale Pb-free magnetic field sensors and magnetoelectric device applications.

Magneto‐Mechano‐Electric Antenna for Portable VLF Transmission

AbstractWireless communication has always been an indispensable element in the modern information‐based society. Beyond the commercial electrical antenna, very low frequency (VLF) mechanical antennas have recently become research hotspot since their combination of miniaturization and favorable radiation efficiency in lossy electrically conductive environments. However, their usage is challenged due to the relatively limited radiation capability and modulation bandwidth. This study demonstrates an improved high‐efficiency magnetoelectric (ME) mechanical antenna based on the magneto‐mechano‐electric (MME) effect, realized via the synergistic effect of piezo‐driven magnets motion and converse magnetoelectricity (ME). Converse ME coefficient and radiation measurement show that the MME antenna demonstrates superior performance over a normal ME antenna. The oscillation magnet serves as an extra vibrating magnetic dipole besides the ME composite and thus brings radiation enhancement to the mechanical antenna. Furthermore, digital signal modulations are conducted with a VLF carrier signal to enable anti‐interference and anti‐attenuation communication. In view of the exemplary demonstration, the MME effect‐based antenna is expected to provide a new strategy for mechanical antenna improvement and shows tremendous potential for conductive environments communication applications.

Giant magnetoelectric effect of Ni–Mn-Ga/piezopolymer composites tailored by a martensitic transformation

Polymer-based magnetoelectric (ME) composites, composed of magnetostrictive and piezoelectric phases, in addition to exhibiting an effective coupling between the magnetic and electric orders of the matter, also offer important advantages for the Internet-of-Things, digitalization, and 4.0 revolution environments: light weight, flexibility, wearability, environmental friendliness, printability, and biocompatibility. Nevertheless, their successful implementation on applications such as sensors, actuators, energy harvesters, biomedical devices and spintronics strongly depends on the increase of its ME voltage response.This work explores, both experimentally and theoretically, the magnetostrictive Ni–Mn-Ga's martensite ‒ austenite phase transformation to shift/tailor/design the ME resonance peak exhibited by Ni–Mn-Ga/P(VDF-TrFE) piezoelectric composites. In the austenite phase, the determined peak value of the ME coefficient of 18.1 V cm−1 Oe−1 was much higher than the value of 6.05 V cm−1 Oe−1 obtained for the martensite phase, whereas the estimated theoretically value of magnetoelastic constant in the austenite is much smaller. The ways to further increase the magnetically induced ME response are also outlined.

Observation of linear magnetoelectric effect in a Dirac magnon antiferromagnet Cu3TeO6

Cu3TeO6, a three-dimensional antiferromagnet forming a unique spin-web lattice of spin-1/2 Cu2+ ions below the Néel temperature TN ≈ 62 K, has recently been found to exhibit topological Dirac or nodal magnon dispersion. In this study, we report the discovery of the linear magnetoelectric (ME) effects in Cu3TeO6 below TN. Our pyroelectric current measurements at a constant magnetic field (H) reveal a linear increase of electric polarization (P) with H for both P//H and P⊥ H configurations; a maximum P//[110] = 20 µC/m2 is obtained at µ0H//11¯0 = 14 T, corresponding to a linear ME coefficient 1.8 ps/m. Magnetic point group analysis and Monte-Carlo simulations confirm that finite linear ME coefficients are allowed in the off-diagonal and diagonal ME tensor components, consistent with the magnetic point group of 3¯′. As the parity-time symmetry can be broken in the presence of H or electric field E in the linear ME materials, we envisage that Cu3TeO6 should exhibit a H- or E-induced transformation in the topological magnon dispersion from a Dirac point/nodal line type into two Weyl point types.