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Magnetoelectric uniaxial metamaterials as wide-angle polarization-insensitive matching layers
摘要： Antire?ection or impedance matching is a topic that has been extensively researched by the optical and microwave communities over the past century and until today. However, due to the diverging wave impedances of TE (s) and TM (p) polarizations with increasing incident angle, it is impossible to achieve perfect matching simultaneously for both polarizations at varying incidence angles with a single conventional isotropic matching layer. To achieve polarization-insensitive matching at an arbitrary incident angle, we propose a magnetoelectric uniaxial metamaterial layer (MEUML) that is inspired by the perfectly matched layer (PML) concept in computational electromagnetics. Similar to the PML, the MEUML requires speci?c uniaxial permittivity and permeability tensors. However, to simultaneously control both the transversal and longitudinal material parameters is not an easy task. To date, a true PML has not been realized with metamaterials. In this paper, we employ a simple and yet special metamaterial unit cell to achieve such control and synthesize a physical MEUML. The unit cell comprises two parallel metallic rings separated by a holey substrate. The transversal electric and magnetic dipole moments, and the longitudinal capacitive and diamagnetic coupling between the rings are judiciously controlled to achieve the required permittivity and permeability tensors. To aid the MEUML synthesis, we also introduce a technique that can extract the material parameter tensors at any incident angle. We ?rst demonstrate this concept by achieving polarization-insensitive matching of a high-index substrate at 45? with a single subwavelength-thick MEUML. We further adapt the concept to the microwave regime by developing a MEUML-based radome. Exceptional matching performance was obtained both in the simulations and measurements. The re?ectance remains below 5% from normal incidence (0?) to near grazing angle (85?) for both polarizations and over a wide bandwidth. With this unprecedented control of the material parameter tensors, the MEUML concept not only can be applied to impedance matching, but also can be utilized in many exotic applications that require extreme control of the material properties.
关键词： wide-angle,impedance matching,polarization-insensitive,radome,magnetoelectric uniaxial metamaterials
更新于2025-09-23 15:21:21
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Magnetoelectric effects at electromechanical resonance in laminates of lead-free piezoelectric bimorph and magnetostrictive component
摘要： The paper presents a theoretical model for magnetoelectric (ME) effect in multilayers of piezoelectric and magnetostrictive components. We assume the piezoelectric layer to be compositionally-stepped. Taking into account the toxicity of lead-based ceramic, piezoelectric component is made of a lead-free piezoelectric. Analytical expressions for ME voltage coefficients is obtained by substituting the expression for stress at bending mode into open electric circuit condition. Using the layered structure based on the compositionally-stepped piezoelectric components leads to an enhanced magnetoelectric coupling for specific component thickness ratio due to an increase in flexural deformation as compared with the bilayer based on homogeneous piezoelectric layer. For the laminate of lead-free piezoelectric langatate bimorph and magnetostrictive Permendur, ME coupling is stronger due to higher ratio of the piezoelectric coupling coefficient to the dielectric constant. In addition, an 80 % increase in magnetoelectric coupling strength due using the compositionally-stepped piezoelectric is obtained.
关键词： electromechanical resonance,magnetoelectric effects,magnetostrictive component,lead-free piezoelectric
更新于2025-09-23 15:21:01
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Investigation on the structural, multiferroic and magnetoelectric properties of BaTi1-xNixO3 ceramics
摘要： In this paper, we report the influence of Ni doping on the structural, electrical, magnetic and magnetoelectric properties of BaTiO3 (BTO) ceramics. X-ray diffraction (XRD) analysis indicates a phase transition from tetragonal to hexagonal at x = 2.5 mol%. Further, XRD data has been refined using Rietveld method to extract the phase formation, lattice parameters, and the phase fraction of BaTi1-xNixO3 (BTNO)(0 ≤ (cid:129) ≤ 10 mol%) ceramics. The ferroelectric polarization decreases with Ni doping concentration. The relative permittivity of BTNO compositions decreases while the corresponding dielectric loss increases with Ni doping concentration. Room temperature magnetic hysteresis (M-H) loop of all BTNO samples exhibit ferromagnetic nature with a saturated loop except for x = 2.5 mol% Ni doping concentration. At x = 2.5 mol% Ni doping concentration, a small amount of diamagnetism is observed at higher fields along with ferromagnetism. The origin of ferromagnetism is due to the F- center exchange interaction via oxygen vacancies. The highest remnant magnetization (Mr) is 11.76 memu/g for x = 10 mol%. The Magnetodielectric coefficient (MD) and magnetoelectric coefficient (ME) gradually increases with increasing Ni doping concentration, and are 1.72 % and 4.51 mVcm !Oe ! respectively for x = 10 mol%.
关键词： ferroelectric,magnetoelectric,Barium titanate,magnetic,multiferroic,Perovskite
更新于2025-09-23 15:21:01
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nonlinear Optics of Multiferroic Materials
摘要： Multiferroics, that is, materials with a coexistence of long-range magnetic and electric order have been attracting tremendous interest because of pronounced coupling effects between magnetic and electric properties that may be the basis for novel devices in which a magnetization is controlled by an electric voltage rather than by energy-intensive electric-current-driven magnetic fields. For monitoring as well as controlling the magnetoelectric coupling, it is essential to have simultaneous access to the magnetic and electric phase of a multiferroic. Only then, the spatial relation between the magnetic and electric domain structures and their response to external perturbations like applied magnetic or electric fields can be studied. Nonlinear optics is particularly well suited for this purpose. The simplest nonlinear optical process is second harmonic generation (SHG) (cid:650) doubling of the frequency of a light wave in a material. SHG is a very symmetry-sensitive process. Any reduction of the symmetry of the frequency-doubling medium can lead to new SHG contributions. Since all types of ferroic order reduce the point group symmetry, SHG can be used as background-free probe of the occurring order. In general, the magnetic and the electric order of a multiferroic change symmetry in different ways so that they are represented by different SHG contributions. These are readily separated by polarization filters so that SHG is an ideal tool to observe the coexistence and correlation between the ferroic phases and their domains in a single experiment. Polarization-dependent SHG spectroscopy and imaging experiments are therefore ideal for analysing the magnetoelectric correlation in a broad variety of multiferroic materials. Some of the most important achievements of nonlinearoptics on multiferroics are: (cid:120) Detection of a coupling between antiferromagnetic and ferroelectric order in hexagonal manganites that occurs in the domain walls rather than in the domains. The result anticipated the current interest in domain walls as functional oxide interfaces [1]. (cid:120) A coupling between magnetic and electric domains in TbMnO3 sustained even across a first-order (cid:120) phase transition [2]. Inversion of a multiferroic domain pattern: The direction of the magnetic or electric order parameter of a multiferroic is reversed across the entire sample, but the domain patterns such is retained [3]. (cid:120) Reversal of a multiferroic domain state without application of external DC fields, just by light [4]. (cid:120) In-situ tracking of the emergence of ferroic order in multiferroic oxide thin films by monitoring the formation of the ordered state by SHG during growth [5]. Optical access in all these experiments involves lasers emitting light pulses of either 100 fs or 5 ns. The laser light can be used to monitor the multiferroic order by nonlinear optics but also, prior to that, to manipulate the ordered state by with an intense pump light beam and analyse the ensuing dynamics. In view of the versatility of the optical access to multiferroics and the generality of the symmetry-based approach to the detection of ferroic phases, it is to be expected that the field of nonlinear optics on multiferroics will continue to develop at the highest speed.
关键词： magnetoelectric coupling,multiferroic materials,second harmonic generation,Nonlinear optics
更新于2025-09-11 14:15:04
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Thin Films with Checkerboard-Ordered Oxygen Vacancies and Low Magnetic Damping
摘要： The possibility of affecting the magnetic properties of a material by dielectric means, and vice versa, remains an attractive perspective for modern electronics and spintronics. Here, we report on epitaxial Bi(Fe0.5Mn0.5)O3 thin films with exceptionally low Gilbert damping and magnetoelectric coupling above room temperature (< 400 K). The ferromagnetic order, not observed in bulk, has been detected with a total magnetization of 0.44 μB/formula units with low Gilbert damping parameter (0.0034), both at room temperature. Additionally, a previously overlooked check-board ordering of oxygen vacancies is observed, providing insights on the magnetic and dielectric origin of the multifunctional properties of the films. Finally, intrinsic magnetodielectric behavior is observed as revealed by the variation of dielectric permittivity well above room temperature. These findings show the possibility of electric-field-controlled magnetic properties, in low Gilbert-damping-based spintronic devices, using single-phase multiferroic materials.
关键词： magnetodielectric,Gilbert damping,thin films,Bi(Fe0.5Mn0.5)O3,magnetoelectric coupling
更新于2025-09-11 14:15:04
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A dual-output magnetoelectric gyrator
摘要： A novel dual-output magnetoelectric (ME) gyrator operating in an acoustic resonance mode and based on a Pb(ZrxTi1-x)O3 (PZT)/Metglas/PZT (P-M-P) trilayer structure is discussed. The dual-output with different current-to-voltage (I-V) conversion ratios and different voltage levels result from the use of piezoelectric layers with different thicknesses as the output ports. Under open circuit conditions, the maximum I-V conversion ratios of the two outputs were 5.7 and 13.5 kV/A at a frequency of 50.4 kHz. A high power efficiency (?) of 91.7% was achieved and remained relatively stable (≥86%) under increasing power drive to a power density of 45 W/in3. These excellent power transfer and multi-output characteristics offer unique possibilities for possible use of ME gyrators in modern power electronic devices.
关键词： acoustic resonance,dual-output,magnetoelectric gyrator,PZT/Metglas/PZT,power transfer
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Modular approach to understanding and synthesis of metamaterials and metasurfaces
摘要： The vast majority of previously proposed metamaterials and metasurfaces are anisotropic or bianisotropic (exhibiting magnetoelectric coupling). Nevertheless, their anisotropy was not fully exploited as they were designed only for one or several specific illumination directions. In this talk, we propose a simple analytical approach to characterize properties of general bianisotropic meta-atoms for an arbitrary illumination. The approach is based on the qualitative decomposition of an arbitrary meta-atom into separate basic “modules” with elementary polarization properties. Such decomposition can be used for comprehensive characterization of previously designed structures as well as for synthesizing novel bianisotropic inclusions of arbitrary complexity and with desired response.
关键词： polarization properties,anisotropy,metamaterials,bianisotropic,metasurfaces,magnetoelectric coupling
更新于2025-09-10 09:29:36
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Nonlinear converse magnetoelectric effects in a ferromagnetic-piezoelectric bilayer
摘要： The strain mediated nonlinear converse magnetoelectric effect (CME) is investigated in a bilayer of an amorphous ferromagnet FeBSiC and piezoelectric lead zirconate titanate (PZT). The magnetic response of the sample to an AC electric ?eld (e) applied to PZT at an acoustic resonance frequency of 76 kHz was measured with a coil wound around the bilayer. With an increase in the amplitude of e over the range 0–250 V/cm, the variation in amplitude of the ?rst and the second harmonics of the induced voltage due to the variation in the magnetic induction B was measured for DC bias magnetic ?eld H ? 0–80 Oe. The coef?cients of the linear and nonlinear converse ME effects were 5.5 G cm/V and 1.9 (cid:2) 10(cid:3)2 G cm2/V2, respectively. The nonlinearity of the CME arises due to the nonlinear dependence of the magnetic induction on the stress. A theoretical model for the nonlinear CME is discussed.
关键词： acoustic resonance,nonlinear converse magnetoelectric effect,stress,magnetic induction,ferromagnetic-piezoelectric bilayer
更新于2025-09-10 09:29:36
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Strain-mediated magnetoelectrics: Turning science fiction into reality
摘要： There is currently a need for an efficient approach to control magnetism at small scales (<1 mm). Work on these magnetoelectric concepts dates back to the 19th century, when researchers believed that a material could convert electrical to magnetic energy, similar to Oersted’s discovery, made by passing a current through a wire. Today, there are significant magnetoelectric research opportunities in both materials discovery and theoretical modeling efforts to advance this important area of magnetic control. Applications for these strain-mediated magnetoelectric materials range from replacing existing inefficient magnetic memory approaches to spearheading new discoveries, such as micrometer-size electromagnetic motors enabling robotic manipulation. This article and the other articles in this issue provide the motivation, background information, research opportunities, and novel applications for studying strain-mediated magnetoelectric materials. The issue is designed to encourage additional research on magnetoelectrics due to its potential impact on society through the efficient control of magnetism at the micro- and nanoscale.
关键词： magnetoelastic,magnetic control,piezoelectric,magnetoelectric,strain-mediated
更新于2025-09-10 09:29:36
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Electrical-poling-induced strain effect in Pb(Fe0.534W0.066Nb0.4)O3
摘要： The electrical control of magnetism is a potential technique for low-energy-consuming spintronic devices. In this work, Pb(Fe0.534W0.066Nb0.4)O3 (PFWN), a known magnetoelectric-multiferroic compound, is poled using dc electric field to study the impact of induced strain on the vibrational modes and magnetism using Raman spectroscopy and magnetic susceptibility measurements, respectively. PFWN exhibits ferroelectric phase transition at TC * 300 K and antiferromagnetic ordering around TN * 187 K coinciding with an anomaly in the temperature-dependent Raman studies, indicating spin-phonon coupling. The observed changes in Raman modes and magnetization of electrically poled PFWN indicate strong converse magnetoelectric coupling effect. The electric-field-induced strain induces tilting of the FeO6 octahedra, which alters hybridization between Fe 3d and O and 2p orbitals, respectively. We present results of our studies on electric poling of PFWN in the light of current interest in the magnetic switching applications of spintronic materials.
关键词： Structure,Vibrational,Multiferroics and magnetoelectric coupling,Magnetism
更新于2025-09-10 09:29:36