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Effect of BaZr <sub/>0.4</sub> Ti <sub/>0.6</sub> O <sub/>3</sub> addition on electrical and magnetic properties of multiferroic (1-x)BiFeO <sub/>3</sub> -xBaTiO <sub/>3</sub> ceramics
摘要： The 0.75((1-x)BiFeO3-xBaTiO3)-0.25BaZr0.4Ti0.6O3 or 0.75(BFO-BTO)-0.25BZT ceramics (x = 0.23–0.27) have been prepared by solid state reaction method to studied the relationship between phase formation, dielectric and magnetic properties. The results found that the phase formations of calcined BFO-BTO and BZT powders are distorted rhombohedral and cubic structure, respectively. Moreover, the addition of BZT in BFO-BTO-BZT ceramics affected to the phase change dramatically according to increasing of BZT content compared to calcined BFO-BTO powders. All the samples showed cubic perovskite structure. The room temperature dielectric properties decreased with increasing of BTO content, the highest dielectric constant with low losses observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic. Furthermore, the ceramics displayed maximum dielectric constant temperature (Tm) above 360 °C. Interestingly, all ceramic compositions exhibited typical ferromagnetic hysteresis loop and the highest remanent magnetization observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic.
关键词： composite,dielectric properties,ferromagnetic hysteresis loops,BFO-BTO,BZT
更新于2025-11-14 17:28:48
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The Use of Magnetic Orientation as a Pinning Modality for Investigation of Photon-Magnon Interactions in Magnetic Nanoparticle Systems
摘要： In this work, an experimental setup to study the dependence of a visible-light transmission through a magnetic granular film on the magnetic field direction was presented. The results measured the transmission (T) of the visible light, with the wavelengths (λ) were in the range from 560 to 695 nm, by the magnetic nanogranular films Cox-(Al2O3)100-x system, with Co compositions are x = 10 ÷ 45 at.%, as a function of the magnetic field direction were reported. These investigations were carried out under an external magnetic field of H = 400 Oe, which directs to the normal of the sample surface by an angle varied in the range of θ = 0° ÷ 45°, to magnetize the magnetization direction of all the Co particles following this direction. Consequently, the angle θ between the magnetization direction with the incident-light direction, which sets as the optical axis of the system and always keeps fixedly to the normal of the sample surface, is established. The experimental results showed the different dependencies of T on the angle θ, the magnetic field H, the Co composition x, and the wavelength λ. These dependencies attributed to a behavior that relates to so-called photon-magnon interaction.
关键词： Ferromagnetic Nanoparticle (FMNP),Visible-Light Transmission,Magnetic Nanogranular Film (MNGF),Plasmonic Spin,Photon-Magnon Interaction
更新于2025-09-23 15:23:52
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Critical Behavior of Ni-doped La0.7Sr0.3MnO3 Ceramics
摘要： The effect of Ni substitution on the magnetic properties and the critical behavior of La0.7Sr0.3Mn1-xNixO3 compounds, which were prepared by the solid-state reaction method has been investigated. Based on our investigations of the temperature and the magnetic field dependences of magnetization M(T, H) data, it is shown that the Curie temperature (TC) of La0.7Sr0.3Mn1-xNixO3 compounds will be shifted toward room temperature with increasing Ni concentration (x), TC = 359–307 K for x = 0.0–0.1. By using the modified Arrott plots and the Kouvel–Fisher methods together with M(H, T) data in the vicinity of the ferromagnetic (FM)–paramagnetic phase transition, the critical exponents (β, γ, and δ) have been determined. Our results show the existence of a short-range FM order in the undoped sample (x = 0). The values of β, γ, and δ will be shifted gradually toward those of the mean-field theory when x increases, suggesting that the long-range FM order is favored in Ni-doped samples. The results calculated on the effective exponents of β_eff(ε) and γ_eff(ε) in the asymptotic region indicate the existence of a magnetic disorder in all the samples.
关键词： manganites,ferromagnetic order,Critical behavior
更新于2025-09-23 15:23:52
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Influence of the phases structure on the acoustic and optical modes ferromagnetic resonance of FeNi stripe domain films
摘要： FeNi films with different phase structures were prepared by electrodeposition method, and the phase structure of the film was controlled by the composition of the film. The results indicated that the well-defined stripe domain patterns and good magnetic properties of the films were fond of the bcc and bcc + fcc phase structures of the FeNi films. The results of permeability spectra indicated that the acoustic and optical modes of the film could be changed by the direction of the microwave field and stripe domain. FeNi stripe domain films exhibited the different frequency under the two modes, and the acoustic and optical modes of film showed obvious spectra in the bcc and bcc + fcc phases of FeNi films. The results are helpful to the development of the stripe domain optical mode microwave devices.
关键词： Phases structure,Stripe domain,Ferromagnetic resonance,Acoustic and optical modes
更新于2025-09-23 15:23:52
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The Magnetic Properties of 1111-type Diluted Magnetic Semiconductor (La1?xBax)(Zn1?xMnx)AsO in the Low Doping Regime
摘要： We investigated the magnetic properties of (La1?xBax)(Zn1?xMnx)AsO with x varying from 0.005 to 0.05 at an external magnetic field of 1000 Oe. For doping levels of x ≤ 0.01, the system remains paramagnetic down to the lowest measurable temperature of 2 K. Only when the doping level increases to x = 0.02 does the ferromagnetic ordering appear. Our analysis indicates that antiferromagnetic exchange interactions dominate for x ≤ 0.01, as shown by the negative Weiss temperature fitted from the magnetization data. The Weiss temperature becomes positive, i.e., ferromagnetic coupling starts to dominate, for x ≥ 0.02. The Mn-Mn spin interaction parameter |2J/kB| is estimated to be in the order of 10 K for both x ≤ 0.01 (antiferromagnetic ordered state) and x ≥ 0.02 (ferromagnetic ordered state). Our results unequivocally demonstrate the competition between ferromagnetic and antiferromagnetic exchange interactions in carrier-mediated ferromagnetic systems.
关键词： ferromagnetic ordering,ferromagnetic coupling,antiferromagnetic exchange interaction,carrier-mediated
更新于2025-09-23 15:22:29
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Design Guidelines for printable Magnetic Shielding Films for NFC Tags on
摘要： The performance of RFID tags deteriorates when mounted on metallic objects. This is due to the induced eddy current effect on the metal which produces a magnetic field that opposes the reader/ tag field. Suitable electromagnetic screening is needed to mitigate this issue e.g. ferromagnetic films shielding the tag from the metal. This paper explores some design guidelines for ferrite films properties for additive manufacturing methods. Simulated and measured results for different ferromagnetic films and their influence on the performance of the NFC tags are investigated.
关键词： NFC,additive manufacturing,ferromagnetic films,RFID
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Ann Arbor, MI (2018.7.16-2018.7.18)] 2018 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Nonlinear Equivalent-Circuit Model for Thin-Film Magnetic Material Based RF Devices
摘要： A nonlinear equivalent-circuit model is developed for thin-film magnetic material based RF devices such as frequency-selective limiter (FSL) and signal-to-noise enhancer (SNE). The ferromagnetic resonance is modeled by a RLC parallel circuit with parameters derived from Kittel’s equations. The nonlinear effect in magnetic material is represented by a pendulum model that predicts cross-frequency coupling as well as parametric oscillations of spins. The coupling of spin waves in different orders is also modeled by coupled nonlinear pendulum resonators with the exchange coupling between the spins represented by coupling inductors. The measurement results of a FSL in literature are used as a reference, and the model successfully predicts the threshold power level, nonlinear insertion loss, and frequency selectivity of the device.
关键词： Ferromagnetic resonance (FMR),Yttrium iron garnet (YIG),nonlinear model,thin film,frequency selective limiter (FSL)
更新于2025-09-23 15:21:21
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nanoparticles
摘要： We report changes on the magnetic behavior of the Heavy-Fermion ferromagnetic YbNi2 alloy when reducing the size of the particles to the nanometer scale by high-energy ball milling. The milling process induces a reduction on the particle size of the bulk alloy down to 10 (2) nm and a lattice strain of 1.8 (2)%, for 30 h of milling time, as calculated from the x-ray diffraction data. The ferromagnetic transition at TC =10.5 K in the bulk alloy tends to disappear whereas other magnetic transitions arise at lower temperatures with the milling process. The AC magnetic susceptibility of the 30 h milled sample shows a frequency independent peak at 3 K, in a wide range of frequencies, consistent neither with superparamagnetic nor simple freezing of the magnetic moments, and as expected for a ferromagnetic behavior. However, from the specific heat measurements in the 30 h milled sample, a peak at 3.6 K is shifted respect to that observed in the AC magnetic susceptibility, as found in spin glasses. Additionally, the specific heat on nanometric samples show reduced magnetic contributions respect to the bulk alloy with ?cmax around 0.45 J/molK. The results are explained by the influence of magnetic inhomogeneities and disorder of the alloys enhanced by the milling process in the ensemble of nanoparticles.
关键词： Specific heat,Ferromagnetic,Spin glass,Magnetic properties,Yb alloys
更新于2025-09-23 15:21:21
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Topological Insulator-Based van der Waals Heterostructures for Effective Control of Massless and Massive Dirac Fermions
摘要： Three dimensional (3D) topological insulators (TIs) are an important class of materials with applications in electronics, spintronics and quantum computing. With the recent development of truly bulk insulating 3D TIs, it has become possible to realize surface dominated phenomena in electrical transport measurements e.g. the quantum Hall (QH) effect of massless Dirac fermions in topological surface states (TSS). However, to realize more advanced devices and phenomena, there is a need for a platform to tune the TSS or modify them e.g. gap them by proximity with magnetic insulators, in a clean manner. Here we introduce van der Waals (vdW) heterostructures in the form of topological insulator/insulator/graphite to effectively control chemical potential of the TSS. Two types of gate dielectrics, normal insulator hexagonal boron nitride (hBN) and ferromagnetic insulator Cr2Ge2Te6 (CGT) are utilized to tune charge density of TSS in the quaternary TI BiSbTeSe2. hBN/graphite gating in the QH regime shows improved quantization of TSS by suppression of magnetoconductivity of massless Dirac fermions. CGT/graphite gating of massive Dirac fermions in the QH regime yields half-quantized Hall conductance steps and a measure of the Dirac gap. Our work shows the promise of the vdW platform in creating advanced high-quality TI-based devices.
关键词： quantum Hall effect,van der Waals heterostructures,Topological insulators,ferromagnetic insulators
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Hermite-Gaussian beams with orbital angular momentum
摘要： A conformal permeable toroidal antenna operating in both a vertically polarized monopole mode and circularly polarized (CP) dipole mode in the UHF frequency range is designed based on theory of magneto-dielectric radiators. This antenna has been fabricated using a new advanced ferromagnetic laminate composite material whose high impedance and anisotropic properties enable an antenna that radiates via magnetic currents. The antenna, less than 0.5 m in diameter and less than 2 cm thick, was fabricated and tested. Including the imperfections of the feed network and a simple matching scheme, the antenna operates from 200 to 500 MHz with an input match of better than 10 dB, CP dipole realized gain as high as 2 dBi, and monopole mode vertically polarized gain as high as 1 dBi.
关键词： ferromagnetic materials,wideband antenna,multimode antenna,multifunction antenna,Conformal antennas
更新于2025-09-23 15:21:01