Search

Domains and domain wall engineering have been extensively explored in ferroic materials for a wide range of applications in nanoelectronics and spintronics. Complex oxides exhibiting strongly correlated properties are model platforms for such studies where response to strain or external stimuli such as electric field, temperature and light can be probed. Here, domains in strained SrMnO3 films, grown on a degenerate semiconductor, allowing for conduction in an out‐of‐plane geometry, are studied using a combination of microscopy probes. Using conductive atomic force microscopy, electrically isolated domains with varying conductance are found and their temporal evolution is investigated. Further, their formation and microstructure are studied using scanning transmission electron microscopy and secondary electron contrast in scanning electron microscopy. An important contribution is establishing that the observed domains are formed by cracks, driven by inhomogeneous strain relaxation throughout the film, resulting in significantly high strain planes. The potential of secondary electrons to detect domain dependent contrast over a large area, ensuing due to the use of a degenerate semiconductor correlates with the conductive properties of the domains and serves as a new direction to probe domains and domain walls in ferroic materials. [ABSTRACT FROM AUTHOR]

We have synthesized (G d 0.2 Y 0.2 N d 0.2 D y 0.2 R 0.2) 3 F e 5 O 12 (R = E r , S m and Pr) high entropy garnet ceramic samples via solid-state reaction route for the first time. All the samples are formed in a single phase and exhibit a simple cubic crystal structure with an I a 3 ‾ d space group. The lattice constant of these samples varies as per the ionic radii of the substituted element and ranges in between 12.4458 Å to 12.5062 Å. The morphology and elemental contributions are also investigated for all the high entropy samples. Additionally, magnetization data reveal a similar value of room temperature saturation magnetization i.e., ∼ 16 e m u / g for (G d 0.2 Y 0.2 N d 0.2 D y 0.2 R 0.2) 3 F e 5 O 12 (R = S m and Pr) samples and it becomes 13.67 e m u / g for Er doped sample. This variation is understood with Dionne's sublattice magnetization model where the molecular weight of the substituent will affect the saturation magnetization. Furthermore, a deviation from ideal Debye-type relaxation behavior is noticed in room temperature Nyquist plots for all three samples. An anomaly in the dielectric plot around ferrimagnetic transition temperature indicates the multiferroic behavior of these high entropy ceramic materials. [ABSTRACT FROM AUTHOR]

The interest in BiFeO3 perovskite for photostable applications is rapidly rising, owing to its efficient single photon emitter behavior. A detailed analysis of the structural, optical and electrochemical behavior of BiFeO3 perovskite synthesized by different synthesis techniques viz. sol–gel and solid-state synthesis techniques, divulging that 30–40-nm-sized-prepared BiFeO3 have well-grown grains but the grain size is non-uniform. The major problem faced in these materials is their photostability under optical excitation. Sol–gel-assisted synthesis procedure exhibited enhanced photostability. Remarkable magnetic and impedance properties of the synthesized material satisfy the competitiveness and also pave a way for the development of perovskite photovoltaics. Hence, the enhancement in the magnetic and impedance properties of BiFeO3 clearly focuses on the importance of sintering atmosphere and also paves a way for BFO thin film for applications in optoelectronics. [ABSTRACT FROM AUTHOR]

The multiferroics with remarkable magnetoelectric (ME) coupling and technological application have drawn significant attention. Here, we report a chemical doping tunable effect on the magnetic, ferroelectric, and dielectric properties in type-II multiferroic Gd 2 BaCuO 5. The magnetic measurement results show that a long-range antiferromagnetic ordering forms at the Néel temperature (T N1) of ∼12.1 K, and a second magnetization anomaly occurs at a lock-in transition temperature (T N2) of ∼6.4 K. Sharp peaks in the pyroelectric and dielectric curves are observed at the magnetic transition temperatures, indicating intrinsic coupling between magnetic and ferroelectric orderings. The doping of Zn2+ results in a gradual enhancement of magnetization due to the increase of uncompensated spins, and large magnetodielectric (MD) coupling parameter up to ∼7.65 % is obtained in Gd 2 BaCu 0.7 Zn 0.3 O 5 because of strong spin-phonon coupling. The ferroelectric property is weakened in Zn2+ doped samples, suggesting the critical role of the 4 f -3 d magnetic interactions in determining the ME coupling effect. Moreover, an effective manipulation of electric field on magnetization is observed in Gd 2 BaCuO 5. This work helps understand the importance of 4 f -3 d magnetic interactions in inducing ferroelectricity and explore the ME and MD coupling effects with multiple magnetic orderings. [ABSTRACT FROM AUTHOR]

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na 0.5 Bi 0.5 TiO 3) and Co–Ti substituted Barium Hexaferrite (BaFe 12-2x Co x Ti x O 19 ; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63 / mmc hexagonal phases corresponding to Na 0.5 Bi 0.5 TiO 3 and BaFe 12-2x Co x Ti x O 19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x ≠ 0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future. [ABSTRACT FROM AUTHOR]

We perform dielectric and impedance spectrums on the compressively-strained ceramics of multiferroic bismuth ferrite. The subsurface-nanolayer quasipolarons manifest the step-like characteristic of pressure-dependent transient frequency and, furthermore, pressure-dependency fails in the transformation between complex permittivity and electrical impedance, which is well-known in classic dielectric physics, as well as the bulk dipole chain at the end of the dissipation peak. [ABSTRACT FROM AUTHOR]

Ferro‐rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo‐FR crystals (i.e., single FR domain). This study explores a cost‐effective approach to growing homo‐FR helimagnetic RbFe(SO4)2 (RFSO) crystals by lowering the crystal growth temperature below the TFR threshold using the high‐pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo‐FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally high TFR of ≈573 K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4 K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates. [ABSTRACT FROM AUTHOR]

Herein, the multiferroic perovskite Er0.9La0.1Cr0.8Fe0.2O3 was synthesized using the sol–gel method, and its structure and multiferroic properties were investigated. The magnetic order of Er0.9La0.1Cr0.8Fe0.2O3 was analyzed through magnetic entropy change curves. Furthermore, a four‐sublattice molecular field model was constructed to study the spin reorientation phenomena and explain the differences between various spin redirections through magnetic order correction. This work will provide a new perspective for studying the properties of type II multiferroic materials. [ABSTRACT FROM AUTHOR]

In the present report, the structure–property correlation of 0.9BaZr0.2Ti0.8O3-0.1NiFe2O4 (0.9BZT-0.1NFO) composite is studied. The X-ray Diffraction, Raman spectroscopy and Field Effect Scanning Electron Microscopy (FESEM) reveal the existence of ferroelectric and magnetic phases without any impurity and interdiffusion. The dielectric, ferroelectric and conductivity mechanisms of the sample are studied in a wide range of temperature (RT-500°C) and frequency (100 Hz–1 MHz), respectively. The dielectric constant is larger than 2000 in low frequency (<1 kHz), while it decreases to 500 when the frequency is larger than 4 kHz. Both small polaron and correlated barrier hopping contribute to the conduction mechanism. The multiferroism at room temperature is confirmed by P-E and M-H loop study. The composite obeys the Law of Approach to Saturation at a higher field. The saturation magnetization found from fitting is in good agreement with the experimental value. [ABSTRACT FROM AUTHOR]

A sol-gel method was employed to synthesize phase-pure (1-x)BiFeO3-xBi(Mn0.5Ti0.5)O3 (abbreviated as BFO-xBMT, x = 0–0.10) multiferroic ferrites. The investigation focused on the structure, optical, and magnetic properties, and their dependence on composition. X-ray diffraction analysis (XRD) revealed a single phase rhombohedral structure for BiFeO3 (BFO), with distinct double peaks (104)/(110) and (006)/(202) at diffraction angles 2θ ∼ 32.0° and 39.5°. As the content of Bi(Mn0.5Ti0.5)O3 (BMT) increased, a structural transition from rhombohedral (R3c) to pseudo-cubic (Pm3m) phase was observed. Doping with BMT led to a decrease in particle size. The band gap (Eg) of BFO-xBMT materials exhibited a slight increase from 1.99 eV in BFO to 2.18 eV in the BFO-0.10BMT composition. The introduction of BMT resulted in a significantly enhanced room temperature ferromagnetism in BiFeO3, with the maximum magnetic moment doubling to around 5.7 emu/g for the BFO-0.04BMT solid solution. This improvement is attributed to the addition of BMT inducing intrinsic strain in the crystal lattice, suppressing the intrinsic helical spin structure of BFO, and thus enhancing its latent magnetic potential. The research demonstrated the substantial influence of BMT perovskite on the structure, optical, and magnetic properties of BFO materials. Overall, the results suggest that the BFO-xBMT multiferroic ferrites with optimal composition hold promise for use in multifunctional devices. [ABSTRACT FROM AUTHOR]

The utilization of magnetoelectric composites, particularly core-shell configurations, enhances their versatile applications in various sectors such as medicine and data storage. Among these composites, the perovskite-spinel combination is distinguished by its significant potential. A series of (1-x) BiFeO 3 -(x) CoFe 2 O 4 (where x = 0.0, 0.2, 0.5, and 1.0) nano core-shell structures were synthesized using a sol-gel auto-combustion method to explore their multifunctional capabilities. Structural analyses identified peaks corresponding to both perovskite and spinel phases. Field Emission Scanning Electron Microscopy revealed a reduction in average particle size with an increase in CoFe 2 O 4 content.The particle size in the BFO80-CFO20 sample has been reduced from 243 nm to 34 nm. Additionally, Transmission Electron Microscopy images of the BFO80-CFO20 sample highlighted the evolution of core-shell structures. Our findings indicate that higher CFO concentrations significantly affect the dielectric, ferroelectric, and optical properties. The bandgaps of the nanocomposites BFO80-CFO20 and BFO50-CFO50 were estimated to be 1.43 eV and 1.39 eV, respectively. Magnetic analysis showed increases in both saturation magnetization and remanent magnetization with increased CFO content, while the coercive field followed a different trend. The saturation magnetization values for the samples BFO, BFO80-CFO20, BFO50-CFO50, and CFO were calculated as 0.205, 14.612, 28.374, and 74.105 (e m u g r) , respectively. The measured values for the same samples were 0.08, 5.07, 11.34, and 34.01 (e m u g r) , respectively. Further, the electrochemical properties were thoroughly investigated using cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

In the present study, SrTiO3 was selected to enhance the multiferroic characteristics of Bi0.88Sm0.12FeO3 (BSF) ceramics. With increasing SrTiO3 content, the principal phase of BSF ceramic transitions from rhombohedral R3c to Pna21. Through DSC and dielectric analysis, it was observed that both the Curie temperature and Néel temperature decreased proportionally with the augmentation of SrTiO3 content. When x =.1, the optimal ferroelectric performance is achieved, and the highest remanent polarization value is 55.47 µC/cm2, significantly surpassing that of BSF ceramics. Moreover, the PFM test results showed that as the substitution content increased, the domains in the BSF ceramic gradually transformed from normal ferroelectric domains to polar nanomicro‐domains. Magnetic and magnetoelectric results show that when x =.1, the best magnetic properties are obtained, Mr = 59.7 emu/mol. The magnetoelectric coefficient αME initially increased and then decreased with the increasing SrTiO3 content, reaching its optimum magnetoelectric properties at x =.1, where αME =.47 mV cm–1 Oe–1. In summary, when the substitution amount of SrTiO3 reaches 10%, the ferroelectric, magnetic, and magnetoelectric properties of BSF ceramics are significantly improved. [ABSTRACT FROM AUTHOR]

Bilayer thin films of GdFeO3/Fe97Si3 have been synthesized by RF–magnetron sputtering at different thicknesses of GdFeO3. A pure phase polycrystalline growth of GdFeO3 and Fe97Si3 has been confirmed by XRD measurements. Stress-induced room-temperature magnetocrystalline anisotropy has been confirmed in all the bilayer thin films. A high magnetic moment has been induced in antiferromagnetic GdFeO3 thin films resulting in the ferromagnetic character of all the samples. The ferromagnetic moment was found to be enhanced with increasing thickness of the GdFeO3 layer. The maximum value of the room- temperature magnetic moment has been observed as Ms ~ 9.3 emu/ml in 170-nm-thick GdFeO3 film. Dielectric measurements confirmed the induced magnetocapacitance due to grain boundary accumulation of charge carriers. Magnetic field control of capacitance and current–voltage measurements of these thin films represents a strong potential for the existence of magnetoelectric coupling in GdFeO3/Fe97Si3 films. A maximum 30% rise in magnetocapacitance and a 95.6% increase in tunneling current in an applied 1-kOe magnetic field was obtained for 170-nm-thick GFO thin film. These thin films possess applications in spintronic devices due to the presence of room- temperature magnetocrystalline anisotropy and magnetic control of the electric properties. [ABSTRACT FROM AUTHOR]

Herein, we report a fundamental study revealing the substantial change in magnetic and electrical properties promoted by manganese (Mn) substitution in the iron (Fe) site of double perovskite LaYFe2O6 [LaYFe2-xMnxO6; x = 0, 0.05, 0.10, and 0.15], which is prepared by the sol–gel auto-combustion method. The structural, morphological, magnetic, and electrical properties of all the samples are investigated to explore the influence of Mn in the compound. X-ray diffraction (XRD) study reveals the confirmation of phase formation with orthorhombic crystal structure having symmetries P21nm and Pbnm (small contribution). X-ray photoelectron spectroscopy (XPS) analysis corroborates the mixed valence state of Fe and Mn, while the dominancy of + 3 oxidation state can be confirmed for them. Magnetization study reveals that the transition temperature reduces drastically (~ 100 K) by the Mn substitution and approaches toward room temperature (RT). At 573 K, the maximum magnetization value enhanced up to ~ 30% by the Mn substitution. Grain boundary contribution in the electrical response is more prominent in the higher Mn content samples. The application of DC magnetic field exhibits a significant influence on the impedance spectra due to the substitution of Mn in the lattice, which corroborates the signature of magnetoelectric (ME) coupling. The presence of ME coupling is further confirmed by the direct magnetoelectric measurement. This finding along with the above RT magnetic transition could make it a feasible candidate for ME-based applications. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The compound BaFe 1 1. 4 In 0. 6 O 1 9 was synthesized in the solid phase and its chemical composition and structural properties were studied. SEM analysis showed that the size of crystallites in the resulting polycrystal is d ≈ 0. 5 − 2 μ m. When analyzing the microcomposition of the surface, 55.8% of Fe, 19.7% of O, 14.3% of Ba, and 10.0% of In atoms were determined. XRD analysis showed that the crystal structure of this compound corresponds to hexagonal (P63mmc) symmetry. The crystallographic parameters of the compound were determined by the Rietveld method. [ABSTRACT FROM AUTHOR]

In this work, h -RFeO 3 multiferroic high-entropy ceramics are designed by introducing high-entropy concept with four elements (Yb, Lu, In, Sc) for R site. (Yb 0.25 Lu 0.25 In 0.25 Sc 0.25)FeO 3 high-entropy ceramics are prepared by the standard solid-state reaction methods. The samples prepared with precursors were identified to crystalize in the pure hexagonal structure with polar space group (P 6 3 cm) at room temperature. By the analysis of the variable XRD patterns, it is speculated that the ferroelectric transition temperature of the sample is above 773 K. Meanwhile, three magnetic anomalies are determined for high-entropy ceramics, which is the antiferromagnetic transition at Néel temperature T Ñ 280 K, the spin-reorientation temperature T SR ∼145 K and the reasonable ferromagnetic-like clusters without long ordering in T N < T < T A (∼397 K). Besides, it is observed that the peak intensity of the pyroelectric current around T N can be tuned by magnetic field, which is indicated the magnetoelectric coupling effect in (Yb 0.25 Lu 0.25 In 0.25 Sc 0.25)FeO 3 high-entropy ceramics. These results indicate the ferroelectric and antiferromagnetic orders are coexist in the h- RFeO 3 high-entropy ceramics as promising near room temperature multiferroic materials, and it is an effective way to obtain a new type single-phase multiferroic materials. [ABSTRACT FROM AUTHOR]

BiFeO3‐BaTiO3‐based ceramics are promising multiferroic materials for a wide range of applications. In this paper, the effects of different ionic valence state((Ga0.5Ta0.5)4+, Ta5+) doping on the structure and properties of 0.73BiFeO3‐0.27BaTi1‐y(Ga1‐xTax)yO3 ceramics were investigated. X‐ray diffraction analysis showed that all samples were determined by rhombohedral R3c phase and tetragonal P4mm phase. A frequency‐independent dielectric anomaly with obvious thermal hysteresis was detected in all samples, indicating the first‐order ferroelectric phase transition, and the Curie temperatures were all above 600°C. The ferroelectric analysis found that the doping of donor element Ta reduced the coercive field, with a slight decrease of remanent polarization, which can be attributed to the soft effect of Ta element. Meanwhile, the magnetic properties were enhanced for all samples, with a maximum in 15T (x = 1, y =.015) sample, where Mr =.13 emu/g. According to relevant analysis, high‐valence element substitution can enhance the magnetic properties and reduce the coercive field of BiFeO3, while low‐valence element substitution can reduce dielectric loss. This result points out a way for us to choose appropriate doping elements to improve the performance of BiFeO3 ceramics. [ABSTRACT FROM AUTHOR]

Bi0.8Ba0.1Er0.1Fe0.96Cr0.02Mn0.02O3 (BBEFCMO) multiferroic ceramic was synthesized through the sol-gel route. The impact of incorporating various dopants into both A and B sites of the BiFeO3 was investigated, and structural, Raman, dielectric, electric, and magnetic properties were studied. X-ray diffraction analysis and Raman spectroscopy revealed a rhombohedral structure with the R3c space group for the doped material (BBEFCMO). Dielectric properties were examined across a frequency range of 102–106 Hz. The present multiferroic material exhibits a colossal dielectric constant and minimal dielectric loss tangent, making it suitable for applications in energy storage. Furthermore, the Cole-Cole type of relaxation was deduced from the imaginary part of the modulus for both grain and boundary-grain contributions. Overall, this study indicates that substituting ions in both A and B sites of BiFeO3 significantly enhances its multiferroic properties, as evidenced by dielectric and magnetic measurements. [ABSTRACT FROM AUTHOR]

Abstract Ferro‐rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo‐FR crystals (i.e., single FR domain). This study explores a cost‐effective approach to growing homo‐FR helimagnetic RbFe(SO4)2 (RFSO) crystals by lowering the crystal growth temperature below the TFR threshold using the high‐pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo‐FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally high TFR of ≈573 K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4 K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates.

Magnon, a quanta of spin waves, can transport in magnetically ordered insulators without substantial heat dissipation. The recently demonstrated magnon‐mediated spin torque through antiferromagnetic insulators is regarded as a highly efficient approach for electrical manipulation of magnetization. To control the magnon transport in antiferromagnets, a very large magnetic field is required, since antiferromagnets show immunity to external magnetic disturbance. The antiferromagnetic order can be electrically controlled in multiferroic materials via the magnetoelectric coupling between the antiferromagnetic and ferroelectric orders. Here, we report the experimental observation of magnon spin transport through multiferroic BiFeO3 thin films in SrRuO3/BiFeO3/NiFe tri‐layers at room temperature. We find highly efficient magnon current transmission through BiFeO3 thin film with a thickness exceeding 80 nm by the spin pumping measurement. The magnon spin‐torque efficiency in the tri‐layers measured by the spin‐torque ferromagnetic resonance is comparable with that in the SrRuO3/NiFe bilayer. This results suggest multiferroic BiFeO3 to be an excellent platform for investigating the antiferromagnetic magnon transport and developing magnonic devices. [ABSTRACT FROM AUTHOR]

The search for novel materials with enhanced characteristics for the advancement of flexible electronic devices and energy harvesting devices is currently a significant concern. Multiferroics are a prominent example of energy conversion materials. The magnetoelectric conversion in a flexible composite based on a piezopolymer layer and a magnetic elastomer layer was investigated. The study focused on investigating the dynamic magnetoelectric effect in various configurations of external alternating and constant homogeneous magnetic fields (L-T and T-T configurations). The T-T geometry exhibited a two orders of magnitude higher coefficient of the magnetoelectric effect compared to the L-T geometry. Mechanisms of structure bending in both geometries were proposed and discussed. A theory was put forward to explain the change in the resonance frequency in a uniform external field. A giant value of frequency tuning in a magnetic field of up to 362% was demonstrated; one of the highest values of the magnetoelectric effect yet recorded in polymer multiferroics was observed, reaching up to 134.3 V/(Oe∙cm). [ABSTRACT FROM AUTHOR]

A series of La and Ti co-doped bismuth ferrite ceramics have been synthesized using the modified sol–gel approach and their crystal structures were verified using X-ray diffraction. Complex impedance analysis has been used to examine the conduction mechanisms and microscopic dielectric relaxations in all of these materials. To examine the behaviour of the dielectric constant's dispersion, the modified Debye's function has been utilized. The dielectric characteristics of each sample have been described using the brick-layer model. In order to understand the conduction mechanism, relaxation period and activation energies, Arrhenius equation and Jonscher's power law were used. The dc conductivity (σDc) decreases significantly by increasing the co-doping percentage of La and Ti which indicates that the dielectric properties of the BFO is improved by the co-doping. The Jonscher's power law fitting parameters indicate that the correlated barrier hopping (CBH) conduction model is followed in all the co-doped samples. Moreover, Electric modulus spectroscopy and the observed values of activation energies suggests the localized and long-range relaxation processes, which are basically non-Debye type relaxation processes. The minimum value of dielectric loss factor was obtained for 10% of La and Ti co-doping. The observed trend in values of activation energies also suggests that the best dielectric properties are obtained for the 10% of La and Ti co-doping in BFO and it retain high dielectric constant up to higher temperature. [ABSTRACT FROM AUTHOR]

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators. [ABSTRACT FROM AUTHOR]

In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications. [ABSTRACT FROM AUTHOR]

In our studies, we combined two powdered materials, i.e., ferroelectric triglycine sulfate (TGS) and ferrimagnetic magnetite Fe3O4, to obtain a magnetoelectric composite. The ferroelectric (E) part, i.e., TGS, was a hybrid organic–inorganic crystal, which we obtained as a pure single crystal from an aqueous solution using a static water evaporation method. The magnetic (M) part of the composite was commercially available magnetite. The samples used for the dielectric and magnetoelectric measurements were cold-pressed and made in the form of a circular tablet. The measuring electrodes were made of silver-based conductive paste and were attached to the sample. We measured the temperature dependencies of selected electrical parameters (e.g., dielectric permittivity, electrical capacity, and loss angle tangent). We used the dynamic lock-in method to check whether magnetoelectric coupling existed between the E and M phases. In this paper, we present the dielectric properties of pure monocrystalline TGS as a reference sample and compare the results for TGS powder, TGS + carbon powder, and TGS + Fe3O4 powder. The magnetoelectric coupling presumably appeared for the composite TGS + 10 wt. % Fe3O4, as evidenced by the shift in the phase transition temperature in the TGS. Moreover, the theoretical interpretation of the effect is proposed. [ABSTRACT FROM AUTHOR]

In this article, we present the results of low-temperature dielectric, magnetic and magnetodielectric properties of BiFeO3 nanoceramics prepared by auto-combustion method. Rietveld refinement results of X-ray diffraction data show that sample crystallizes in single-phase rhombohedral perovskite structure with R3c (No. 161) space group. The average crystallite size was found to be ≈ 600 Å from Williamson–Hall analysis. The temperature-dependent dielectric data have been presented in permittivity and modulus formalism to understand the relaxation dynamics. Three non-Debye-type relaxation processes were observed in the experimental window (173 to 423 K), which are explained using Kohlrausch–Williams–Watts (KWW) decay function. The temperature variation of relaxation times obeys Arrhenius's behaviour. The anomaly observed in the temperature dependence of relaxation times data near 240 K corresponds to the magnetic transition of BiFeO3. We found that single ionized oxygen vacancies with activation energy ranging from 0.4 to 0.8 eV are involved in the relaxation process. A crossover from AFM/PM to weak ferromagnetic ordering is observed at low temperature. The variation of capacitance with an applied magnetic field shows a hysteresis effect. The magnetocapacitance (MC%) changes by 3% at a magnetic field of 2 T for 200 kHz, indicating an intrinsic bulk magnetocapacitance effect in the ceramics. Hence, the above findings highlight the significance of the material as a potential candidate for device applications. [ABSTRACT FROM AUTHOR]

It is well established that many material properties, such as multiferroicity, magnetoresistance, or magnetoelectricity, emerge from strong interactions of spins and lattice (phonons). An in-depth understanding of spin-phonon coupling is key to understanding these properties. We demonstrate strong spin-phonon coupling in HoCrO3 using powder X-ray diffraction measurements. Our investigations confirm magnetoelastic effects below antiferromagnetic phase transition, TN • 142 K. The lattice parameters and unit cell volume decrease normally with temperature up to ~ TN, but decrease anomalously below TN. By fitting the background thermal expansion for a non-magnetic lattice using the Debye-Grüneisen equation, we determined the lattice strain ΔVM due to the magnetoelastic effects as a function of temperature. We have also established that the lattice strain due to the magnetoelastic effect in HoCrO3 couples with the square of the ordered magnetic moment of the Cr3+ ion. [ABSTRACT FROM AUTHOR]

It is well established that many material properties, such as multiferroicity, magnetoresistance, or magnetoelectricity, emerge from strong interactions of spins and lattice (phonons). An in-depth understanding of spin-phonon coupling is key to understanding these properties. We demonstrate strong spin-phonon coupling in HoCrO3 using powder X-ray diffraction measurements. Our investigations confirm magnetoelastic effects below antiferromagnetic phase transition, TN • 142 K. The lattice parameters and unit cell volume decrease normally with temperature up to ~ TN, but decrease anomalously below TN. By fitting the background thermal expansion for a non-magnetic lattice using the Debye-Grüneisen equation, we determined the lattice strain ΔVM due to the magnetoelastic effects as a function of temperature. We have also established that the lattice strain due to the magnetoelastic effect in HoCrO3 couples with the square of the ordered magnetic moment of the Cr3+ ion. [ABSTRACT FROM AUTHOR]

This work successfully synthesized single-phase Aurivillius Bi4Ti2.75(FeNb)0.125O12 using a molten salt method and the natural precursor of Fe3+ ions extracted from Padang Beach sand. The study extensively examined the phase formation, crystal structure, grain morphology, and physical properties. X-ray diffraction (XRD) analysis combined with the Rietveld refinement technique confirms that Bi4Ti2.75(FeNb)0.125O12 adopts a B2cb orthorhombic structure. The refined atomic positions reveal that Bi3+ ions are located in the A-site within both the bismuth and perovskite layers, while the B-sites within the perovskite layers are primarily occupied by Ti4+/Nb5+/Fe3+ ions. The lower distortion of the inner B(1)O6 octahedra suggests the preference of Fe-rich clusters. The magnetization hysteresis suggests that the Bi4Ti2.75(FeNb)0.125O12 phase exhibits a weak antiferromagnetic state arising from the local short-range Fe–O–Fe antiferromagnetic ordering in the inner B(1)O6 octahedra. The electrical measurements reveal that the existence of ferroelectric ordering at room temperature comes from the structural distortion and the off-center ionic displacement. The energy storage capacity of 10.15 mJ/cm3 and efficiency (η) of 50.2% were obtained in ceramic sample under an electric field of 70 kV/cm at room temperature.

We perform dielectric and impedance spectrums on the compressively-strained ceramics of multiferroic bismuth ferrite. The subsurface-nanolayer quasipolarons manifest the step-like characteristic of pressure-dependent transient frequency and, furthermore, pressure-dependency fails in the transformation between complex permittivity and electrical impedance, which is well-known in classic dielectric physics, as well as the bulk dipole chain at the end of the dissipation peak.

Transition metal perovskite oxide membranes and their unique properties have attracted great attention recently and have been developed into one of the research frontiers in condensed matter physics and materials science. Free of constraint imposed by the underlying substrate, freestanding membranes exhibit extraordinary structural tunability and flexibility far exceeding the bulk materials and epitaxial films clamped on substrates, which substantially extends the explorable regime in the phase diagrams. Moreover, high‐quality oxide membranes, even down to a single unit cell, can be synthesized and stacked/integrated with any materials for novel artificial heterostructures and electronic applications. The exceptional structural tunability and stacking ability in oxide membranes provide new knobs to explore the spontaneous symmetry breaking in oxides, providing a fertile playground for emergent primary ferroic/multiferroic properties and electronic applications. Here, the recent progress is briefly reviewed and the promising outlook for future research in ferroic perovskite oxide membranes and their applications is discussed. [ABSTRACT FROM AUTHOR]

Magneto-mechano-electric (MME) generators efficiently harness ubiquitous stray magnetic fields and convert them into electricity, capturing significant attention for powering innumerable wireless sensors. In this study, lead-free 0-3 particulate magnetoelectric (ME) nano-composite ceramics, specifically x(Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3)-(1-x)Ni 0.5 Zn 0.5 Fe 2 O 4 [x(BCT-BZT)–(1-x)NZFO], were synthesized using the sol-gel method. Subsequently, a flexible MME generator was designed, incorporating the optimized ME composite. Structural parameter calculations indicated higher tetragonal distortion of 0.4% in 0.4(BCT-BZT)-0.6NZFO, possibly due to uniform particulate distribution. The ME composites displayed uniform dual-phase microstructures, with 0.4(BCT-BZT)-0.6NZFO showing a higher NZFO concentration. The maximum values of the magnetodielectric (MD) and ME coupling coefficients have been determined to be -3.6% and 2.55 mV cm -1 Oe-1, respectively, for an x = 0.4 composite. The MME generator is designed using an optimized 0.4(BCT-BZT)-0.6NZFO ME composite with film thickness of 34 μm. This MME generator harvests a sinusoidal wave with a maximum output peak-to-peak voltage of 4.1 V when exposed to a weak AC magnetic field of 10 Oe at a frequency of 50 Hz. Additionally, the device demonstrates an exceptional optimal DC power density of 3.89 μW cm-3. The lead-free 0-3 particulate ME composite enables effective magnetic energy harnessing. As a result, it holds great promise as an efficient autonomous power supply for various Internet of Things based applications. [ABSTRACT FROM AUTHOR]

Sol-gel method is used to synthesize the Bi0.90Dy0.10FeO3-BaTi0.95Hf0.05O3 (BDyFO-BTHfO composite) multiferroic composite material. The structural formation was examined utilizing an X-ray diffraction (XRD) pattern preceded by Rietveld refinement utilizing the FULLPROF programme to confirm the presence of tetragonal and partially rhombohedral structures having space group P4mm and R3c, respectively. The dielectric characteristics of the BDyFO-BTHfO composite have been measured with respect to frequency (100 Hz to 1 MHz) and temperature (RT to 663K). Dielectric permittivity (ε) shows low-frequency dispersion which can be addressed by Maxwell-Wanger-type interfacial polarization. The synthesized composite material exhibits a negative magneto-dielectric (MD) effect when a magnetic field is operated (0.0 T to 2.0 T) and the obtained values are −9.61% and −19.68% for the ε and tanδ, respectively, at 1 kHz. The contribution of the grains, grain boundaries and electrode effects on the resistive characteristics of the samples was evaluated using comprehensive impedance spectroscopy using a Nyquist plot. The band gap (Eg) absorption of the synthesized sample was determined using Tauc's formula and found to be 2.05 eV. The BDyFO-BTHfO composite has improved magneto-dielectric, magneto impedance, and optical properties that support their potential usage in microelectronics, energy storage devices, and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The pseudo-potential PAW method of the density functional theory is employed to study the localization of superstoichiometric oxygen in ferrite CaBaFe4O7 with the orthorhombic swedenborgite structure. The geometric characteristics of oxygen defects are determined by the crystal lattice relaxation procedure. It is shown that the formation of defects in calcium and barium coordination are energetically unfavorable. Oxygen intercalation into structural trigonal iron-oxygen and Kagomé layers is more favorable. In these layers, two edge-sharing Fe2O5 bipyramides are formed instead of FeO4 tetrahedra connected via one oxygen atom. The structural instability of ferrite CaBaFe4O7 is shown to be caused by the population of anti-bonding 2p O states during oxygen intercalation. The asymmetric location of the intercalated oxygen ion relative to the neighboring iron ions promotes the appearance of local electric polarization, which can induce ferroelectric effects in the presence of ferromagnetic order. [ABSTRACT FROM AUTHOR]

We report the magnetic-field-assisted electric-field-controlled domain switching of a magnetic single domain in a multiferroic/magnetoelectric Ni nanochevrons/[Pb(Mg1/3Nb2/3)O3]0.68–[PbTiO3]0.32 (PMN–PT) layered structure. Initially, a magnetic field was applied in the transverse direction across single-domain Ni nanochevrons to transform each of them into a two-domain state. Subsequently, an electric field was applied to the layered structure, exerting the converse magnetoelectric effect to transform/release the two-domain Ni nanochevrons into one of two possible single-domain states. Finally, the experimental results showed that approximately 50% of the single-domain Ni nanochevrons were switched permanently after applying our approach (i.e., the magnetization direction was permanently rotated by 180 degrees). These results mark important advancements for future nanoelectromagnetic systems. [ABSTRACT FROM AUTHOR]

We investigated the ferroelectric switching dynamics as well as the multiferroic and piezoelectric properties of highly a‐oriented epitaxial Bi5Ti3FeO15 (BTFO) thin films on Nb‐doped SrTiO3 single crystal substrates. The BTFO thin films favored highly a‐oriented crystallinity because c‐oriented crystallinity decreased under deposition conditions in which substrate temperature and thin film deposition rate were simultaneously lowered. The highly a‐oriented epitaxial BTFO thin films showed the best ferroelectric properties, whereas the highly c‐oriented epitaxial BTFO thin films showed the best ferromagnetic properties. In particular, the BTFO thin films in which a‐ and c‐oriented crystallinity were properly mixed showed the best piezoelectric properties. [ABSTRACT FROM AUTHOR]

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators.

Bi0.8Ba0.1Er0.1Fe0.96Cr0.02Mn0.02O3 (BBEFCMO) multiferroic ceramic was synthesized through the sol-gel route. The impact of incorporating various dopants into both A and B sites of the BiFeO3 was investigated, and structural, Raman, dielectric, electric, and magnetic properties were studied. X-ray diffraction analysis and Raman spectroscopy revealed a rhombohedral structure with the R3c space group for the doped material (BBEFCMO). Dielectric properties were examined across a frequency range of 102–106 Hz. The present multiferroic material exhibits a colossal dielectric constant and minimal dielectric loss tangent, making it suitable for applications in energy storage. Furthermore, the Cole-Cole type of relaxation was deduced from the imaginary part of the modulus for both grain and boundary-grain contributions. Overall, this study indicates that substituting ions in both A and B sites of BiFeO3 significantly enhances its multiferroic properties, as evidenced by dielectric and magnetic measurements.

In the search for environmentally friendly materials with a wide range of properties, polymer composites have emerged as a promising alternative due to their multifunctional properties. This study focuses on the synthesis of composite materials consisting of four components: bacterial nanocellulose (BNC) modified with magnetic Fe3O4, and a mixture of BaTiO3 (BT) and polyvinylidene fluoride (PVDF). The BT powder was mechanically activated prior to mixing with PVDF. The influence of BT mechanical activation and BNC with magnetic particles on the PVDF matrix was investigated. The obtained composite films' structural characteristics, morphology, and dielectric properties are presented. This research provides insights into the relationship between mechanical activation of the filler and structural and dielectric properties in the PVDF/BT/BNC/Fe3O4 system, creating the way for the development of materials with a wide range of diverse properties that support the concept of green technologies. [ABSTRACT FROM AUTHOR]

Two-dimensional multiferroic (2D) materials have garnered significant attention due to their potential in high-density, low-power multistate storage and spintronics applications. MXenes, a class of 2D transition metal carbides and nitrides, were first discovered in 2011, and have become the focus of research in various disciplines. Our study, utilizing first-principles calculations, examines the lattice structures, and electronic and magnetic properties of nitride MXenes with intrinsic band gaps, including V2NF2, V2NO2, Cr2NF2, Mo2NO2, Mo2NF2, and Mn2NO2. These nitride MXenes exhibit orbital ordering, and in some cases the orbital ordering induces magnetoelastic coupling or magnetoelectric coupling. Most notably, Cr2NF2 is a ferroelastic material with a spiral magnetic ordered phase, and the spiral magnetization propagation vector is coupled with the direction of ferroelastic strain. The ferroelectric phase can exist as an excited state in V2NO2, Cr2NF2, and Mo2NF2, with their magnetic order being coupled with polar displacements through orbital ordering. Our results also suggest that similar magnetoelectric coupling effects persist in the Janus MXenes V8N4O7F, Cr8N4F7O, and Mo8N4F7O. Remarkably, different phases of Mo8N4F7O, characterized by orbital ordering rearrangements, can be switched by applying external strain or an external electric field. Overall, our theoretical findings suggest that nitride MXenes hold promise as 2D multiferroic materials. [ABSTRACT FROM AUTHOR]

The extraordinary physical characteristics and enormous potential for technological applications of multiferroic materials have sparked recent interest in these materials. In this work, the composition of aliovalent ions Ba2+/Ti4+ doped YMnO3 i.e., Y0.95Ba0.05Mn0.95Ti0.05O3 ceramic sample was prepared through the solid-state method. The structural, dielectric, and ferroelectric properties of the prepared sample were studied in detail. X-ray diffraction patterns unveil the hexagonal crystal structure of the ceramic owning P63cm space group symmetry, which is also authenticated by accomplishing Rietveld's refinement of the sample. Nevertheless, the ceramic demonstrated the emergence of the orthorhombic peak. The formation of phase composition of the prepared sample was proved through FT-IR spectroscopic measurement. The Raman spectroscopy analysis of the sample reveals the presence of subtle vibrational modes. The investigation of the dielectric and electrical properties of the prepared sample at frequencies between 1 kHz and 1 MHz and temperatures spanning from 303 to 623 K has yielded significant outcomes. These outcomes include dielectric dispersion, conduction mechanism, and relaxation process of the samples, which are highlighted in this study. The ferroelectric behaviour of the prepared sample has been studied using PE hysteresis loop measurement. [ABSTRACT FROM AUTHOR]