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Abstract Control of magnetic permeability through voltage in magnetoelectric materials promises to create novel voltage tunable inductors. Domain-level phase field modeling and computer simulation are employed to study magnetoelectric composites of Co-modified NiCuZn ferrite and PZT, where ferrite outperforms metallic magnetostrictive materials at high frequencies important for inductor applications. The simulations focus on the interplay between magnetocrystalline anisotropy and stress-induced anisotropy and reveal different regimes of permeability and tunability behaviors. It is shown that the permeability and its tunability can be significantly increased by reducing the intrinsic magnetocrystalline anisotropy through doping NiCuZn-ferrite with Co2+ to form solid solution (1- x)(Ni 0.6 Cu 0.2 Zn 0.2)Fe 2 O 4 - x CoFe 2 O 4 , and the optimal performance is achieved at vanishing magnetocrystalline anisotropy constant K 1 = 0 corresponding to composition x ∼0.02. The findings are confirmed by complementary experiments with good agreements. The effect of internal bias stress is further investigated, which is shown to shift the permeability regimes and thus provides an effective engineering technique to optimize the voltage tunable inductor performance. A tunability as high as ∼500% is obtained under the optimal condition, which is much higher than that obtained in conventional high-frequency voltage tunable inductors. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In this study, we demonstrate a co-fired magnetoelectric (ME) laminate consisting of piezoelectric/magnetostrictive/piezoelectric layers with unipoled piezoelectric transformer structure. The ME transformer was characterized by quantifying the voltage gain variation and resonance frequency shift as a function of applied DC magnetic field. We delineate the magnetic tunability feature by considering the magnetoelectric coupling and delta-E effect, where E represents the modulus of magnetic material. The ME response of the composite structure was found to be 473mV/cm. Oe exhibiting DC field sensitivity of 100 nT under AC field of 1 Oe at 1 kHz. At a magnetic bias of 60 Oe, the transformer exhibited large frequency tunability of the order of 1.4Hz/Oe. These results present significant advancement towards developing on-chip magnetic-field-tunable devices. [ABSTRACT FROM AUTHOR]

We report a magnetoelectric energy harvester structure that can simultaneously scavenge magnetic and vibration energy in the absence of DC magnetic field. The structure consisted of a piezoelectric macro-fiber composite bonded to a Ni cantilever. Large magnetoelectric coefficient ∼50 V/cm Oe and power density ∼4.5 mW/cm3 (1 g acceleration) were observed at the resonance frequency. An additive effect was realized when the harvester operated under dual-phase mode. The increase in voltage output at the first three resonance frequencies under dual-phase mode was found to be 2.4%, 35.5%, and 360.7%. These results present significant advancement toward high energy density multimode energy harvesting system. [ABSTRACT FROM AUTHOR]

Co-fired magnetostrictive/piezoelectric/magnetostrictive laminate structure with silver inner electrode was synthesized and characterized. We demonstrate integration of textured piezoelectric microstructure with the cost-effective low-temperature co-fired layered structure to achieve strong magnetoelectric coupling. Using the co-fired composite, a strategy was developed based upon the hysteretic response of nickel-copper-zinc ferrite magnetostrictive materials to achieve peak magnetoelectric response at zero DC bias, referred as self-biased magnetoelectric response. Fundamental understanding of self-bias phenomenon in composites with single phase magnetic material was investigated by quantifying the magnetization and piezomagnetic changes with applied DC field. We delineate the contribution arising from the interfacial strain and inherent magnetic hysteretic behavior of copper modified nickel-zinc ferrite towards self-bias response. [ABSTRACT FROM AUTHOR]

Highly dense 1 μm-thick piezoelectric film was deposited on magnetostrictive substrate [platinized nickel-zinc ferrite (NZF)]. A strong magnetic coupling between the piezoelectric film and magnetostrictive NZF substrate was measured exhibiting the maximum magnetoelectric (ME) coefficient on the order of 140 mV/cm Oe at the conditions of HDC = 50 Oe and HAC = 1 Oe at f = 1 kHz. This giant ME coupling under low DC magnetic field condition is attributed to effective elastic coupling. A rotation-type dynamic strain distribution was observed on the PZT film surface which provides information about the nature of elastic coupling. [ABSTRACT FROM AUTHOR]

Magnetoelectric voltage tunable inductors (VTIs) offer a new paradigm for power electronics circuit design. Here, air-gapped VTIs are demonstrated exhibiting a large inductance tunability of 220% with applied fields under 20 kVcm−1 and operational stability up to 5 MHz that covers the full frequency range of the state-of-the-art power electronics. The design of air-gapped VTI comprises of two C-shaped ferrite cores, one permeability-variable magnetic flux valve (MFV) in between C-shaped cores, and slotted air gap between cores and MFV. The tunability of VTIs is achieved through the electric field modulation of permeability in the MFV based on the magnetoelectric effect. There is a tradeoff between the tunability and saturation current. The introduction of air gap significantly reduces the tunability but provides methodology toward increasing the saturation current and power handling capability due to the increased reluctance. The inductance and tunability reduces by 50% with increase in the air-gap width from 0.07 mm to infinity (condition with no C-shaped cores). Phase field simulations demonstrate that the air gap affects the magnetization, permeability, and tunability of VTIs by tailoring the demagnetization field that further influences the magnetic domain rotation process. VTIs with increased frequency range and saturation current will strengthen the continued development of tunable power electronics. [ABSTRACT FROM AUTHOR]

In this paper, single-phase multiferroic ceramics of (1 - x) BaTiO3 - x BiFeO3 (BT - x BFO) were synthesized by solid-solution method in the wide range of material composition (x = 0.025 - 1.0). The changes in crystal structure were confirmed via X-ray diffractions (XRD) and atomic pair distribution functions (PDFs). The room-temperature ME coupling was found to exhibit significant magnitude in the narrow composition window (x = 0.71 - 0.8) where the average crystal structure was found to be rhombohedral. Especially, the BT - 0.725 BFO ceramics containing local monoclinic distortions within rhombohedral phase were found to exhibit high room-temperature ME coefficient (αME) of 0.87 mV/cm·Oe with high piezoelectric properties (g33 = 18.5 × 10 mV m N-1 and d33 = 124 pC N-1). We believe that the high room-temperature ME coupling in single-phase lead-free BT-BFO ceramics provides a possibility of developing electrically or magnetically tunable thin-film devices. [ABSTRACT FROM AUTHOR]

We synthesized epitaxial BTO-BFO heterostructure with decreased leakage and simultaneously improved the multiferroic properties. This study provides new direction for ferromagnetic resonance studies, in high quality BTO-BFO films grown on LSMO. We observed small Gilbert damping (α=0.004) and the absence of large inhomogeneous broadening, in a film with 80 nm thickness of BTO-BFO on LSMO (110). This fact offers opportunities for employing this material system for spin transfer in multifunctional materials where controlling magnetization by a flow of spin angular momentum, or spin current, is crucial toward developing nanoscale spin-based memory and devices. Magnetic insulators, such as BTO-BFO on LSMO, are potentially excellent candidates for pure spin current without the existence of charge current. [ABSTRACT FROM AUTHOR]

Abstract: Internet of Things (IoT) is driving the development of new generation of sensors, communication components, and power sources. Ideally, IoT sensors and communication components are expected to be powered by sustainable energy source freely available in the environment. Here, a breakthrough in this direction is provided by demonstrating high output power energy harvesting from very low amplitude stray magnetic fields, which exist everywhere, through magnetoelectric (ME) coupled magneto‐mechano‐electric (MME) energy conversion. ME coupled MME harvester comprised of multiple layers of amorphous magnetostrictive material, piezoelectric macrofiber composite, and magnetic tip mass, interacts with an external magnetic field to generate electrical energy. Comprehensive experimental investigation and a theoretical model reveal that both the magnetic torque generated through magnetic loading and amplification of magneto‐mechanical vibration by ME coupling contributes toward the generation of high electrical power from the stray magnetic field around power cables of common home appliances. The generated electrical power from the harvester is sufficient for operating microsensors (gyro, temperature, and humidity sensing) and wireless data transmission systems. These results will facilitate the deployment of IoT devices in emerging intelligent infrastructures. [ABSTRACT FROM AUTHOR]

This study demonstrates the modulation of off-resonance magnetoelectric ( ME) response of the Pb(Zr,Ti)O3 ( PZT)/ Metglas (Fe BSi) bilayered composite by laser annealing. A continuous-wave 532 nm Nd: YAG laser with varying fluences (210-390 J/mm2) was utilized to anneal the 2 μm thick PZT film deposited using granule spray in vacuum ( GSV) technique on magnetostrictive amorphous Metglas foil. It was found that the dielectric and ferroelectric properties of the PZT film are strongly affected by the exposure to laser fluence. The ME voltage coefficient of PZT/Metglas increased with the fluence up to 345 J/mm2, reaching a high value of 880 mV/cm·Oe. The electrical and ME properties were correlated with the changes observed in crystallinity and grain size of the PZT film as well as with the alterations in microstructure and magnetic behavior of Metglas. Our results demonstrate that enhanced ME coupling can be realized in PZT/Metglas film composites by controlling the laser fluence. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication and performance results of a magnetoelectric macro fiber composite (ME MFC). The magnetoelectric composite was fabricated by bonding a magnetostrictive layer to a piezoelectric layer using a novel approach of low temperature transient liquid phase (LTTLP) bonding. The composite was diced into 150 micron wide fibers and bonded to a custom designed copper flexible circuit using a spin coated low viscosity room temperature curing epoxy. ME MFC’s with varying ferrite thicknesses of 0.6 mm and 0.5 mm were fabricated and characterized for energy harvesting. The composite with 0.6 mm ferrite thickness achieved an open circuit voltage of 101 mV (ME voltage coefficient of 6740 mV/cmOe) and peak power of 3.1 nW across 356 kΩ matching load at 264 Hz. [ABSTRACT FROM AUTHOR]

A highly dense, 4 lm-thick Pb(Zr,Ti)O3 (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longerwavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas filmcomposites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices. [ABSTRACT FROM AUTHOR]

In this paper, we discuss how the material parameters of piezoelectric phase affect the magnetoelectric properties of the laminate composite especially focusing on the role of loss factors and electromechanical resonance of piezoelectric phase. By analyzing experimental results of magnetoelectric laminate composite consisting of Pb(Zr,Ti)O3-based piezoelectric layer and Metglas ferromagnetic layers, we demonstrate that the losses of piezoelectric materials play an important role in controlling the magnetoelectric sensitivity of the laminate composite. Further, we show that direct magnetoelectric effect is maximized at anti-resonance frequency while the converse magnetoelectric effect is maximized at resonance frequency of the laminate composite. [ABSTRACT FROM AUTHOR]

The novel Cu- and Mn-doped and Cu/Mn codoped 0.75BiFeO-0.25BaTiO magnetoelectric ceramics were successfully prepared by a solid-state reaction method. The dielectric, ferroelectric, ferromagnetic, and magnetoelectric properties were determined and all the results suggested that Cu and Mn dopants occupied different B-site lattices in the 0.75BiFeO-0.25BaTiO structure. To identify the preferential sites of Cu and Mn in the lattice, Synchrotron X-ray Absorption Spectroscopy (SXAS) measurements were carried out. A combination of both measured and simulated XAS results with a linear combination fitting (LCF) revealed that in Cu- and Mn-doped 0.75BiFeO-0.25BaTiO ceramics both Mn and Cu substituted at Fe-site and Ti-site with slightly different proportion. On the other hand, both dopants were found to occupied different sites in Cu/Mn codoped 0.75BiFeO-0.25BaTiO ceramics. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate self-biased magnetoelectric effect in homogenous two-phase magnetostrictive-piezoelectric laminates. Our results illustrate the method for tuning the magnitude of self-bias effect and provide understanding behind the hysteretic changes. We model this phenomenon by considering the magnetization hysteresis with shape-induced demagnetization effect. The self-biased response was found to be directly related to the nature of magnetization and can be tuned by variation in demagnetization state and the resultant differential magnetic flux distribution. These results present significant advancement toward development of AC magnetic field sensor and magnetoelectric composite based on-chip devices by eliminating the need for DC bias. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME) composites that simultaneously exhibit ferroelectricity and ferromagnetism have recently gained significant attention as evident by the increasing number of publications. These research activities are direct results of the fact that multiferroic magnetoelectrics offer significant technological promise for multiple devices. Appropriate choice of phases with co-firing capability, magnetostriction and piezoelectric coefficient, such as Ni-PZT and NZFO-PZT, has resulted in fabrication of prototype components that promise transition. In this manuscript, we report the properties of Ni-PZT and NZFO-PZT composites in terms of ME voltage coefficients as a function of frequency and magnetic DC bias. In order to overcome the problem of toxicity of lead, we have conducted experiments with Pb-free piezoelectric compositions. Results are presented on the magnetoelectric performance of Ni-NKN, Ni-NBTBT and NZFO-NKN, NZFO-NBTBT systems illustrating their importance as an environmentally friendly alternative. [ABSTRACT FROM AUTHOR]