Negative Magnetic Permeability Research Articles

Enhancing electromagnetic shielding performance of cement-based materials using industrial waste copper swarf

With growing concerns over electromagnetic interference (EMI) in our surrounding environment, the impact of electromagnetic waves (EMW) on human health and electronic devices is increasingly drawing attention. This study explores the preparation methods of cement-based electromagnetic shielding materials by incorporating copper swarf waste produced by metal processing factories into the cement. It is realizing the recycling and utilization of discarded metal resources and producing copper swarf cement-based materials (CSCBM). Mechanical properties, electrical conductivity, related electromagnetic parameters and shielding efficiency of the material under the X-band were discussed in detail. This study provides new insights into the future recycling and utilization of copper swarf, as well as offering a reference investigation for the recycling of other types of metal swarf. In this study, compressive and flexural strengths were considered, while the morphology and position of copper swarf within the specimens were examined from both macroscopic and microscopic perspectives, taking into account the impact of the morphology and position of copper swarf on compressive and flexural strengths. Through discussions on complex permittivity and resistivity, it was concluded that copper swarf enhances electromagnetic shielding effectiveness by increasing the complex permittivity and reducing the matrix resistivity. Furthermore, based on previous studies, this research provides a theoretical analysis of the negative magnetic permeability phenomenon, offering support for future investigations into negative magnetic permeability phenomena. Under an electromagnetic field, eddy currents will be generated inside the CSCBM, which makes the magnetic permeability of the CSCBM negative. This research forms a foundation for enhancing the EMI shielding effects of cement-based materials using industrial copper swarf.

Metamaterial Inspired Resonators as Microwave Sensors: A Review

Metamaterial-based devices show properties like negative magnetic permeability and negative electrical permittivity, which are not found naturally. Due to their extraordinary sensitivity to nearby perturbations, metamaterial structures have recently emerged as highly desirable and effective techniques of detection. Wide dynamic range, multi-functionality, and simple design and production are a few benefits of metamaterial-based structures. The sensitivity and limit of detection for sensors based on metamaterials can be enhanced by properly altering the device parameters. With the inclusion of microfluidics in metamaterial-based sensors, the sensitivity, selectivity, and detection limit can also be improved. In this review, we have focused on the various meta-surfaces employed for sensing purposes. We have provided a brief introduction to the principle and working of sensors based on meta-surfaces. The main content of the paper is a detailed review of metamaterial-inspired microwave sensor device applications in different fields. These fields include applications in biological sensing, chemical and fuel sensing, physical sensing (includes temperature, strain, displacement, and thickness measurement), and non-destructive techniques for structural health monitoring.

A direct laser-synthesized magnetic metamaterial for low-frequency wideband passive microwave absorption

Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions. Herein, we report a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies, which results in a wide bandwidth in the L- to S-band. Control of the electrical sheet resistance uniformity has been achieved with less than 5% deviation at 400 Ω sq−1 and 6% deviation at 120 Ω sq−1, resulting in a microwave absorption coefficient between 97.2% and 97.7% within a 1.56–18.3 GHz bandwidth for incident angles of 0°–40°, and there is no need for providing energy or an electrical power source during the operation. Porous N- and S-doped turbostratic graphene 2D patterns with embedded magnetic nanoparticles were produced simultaneously on a polyethylene terephthalate substrate via laser direct writing. The proposed low-frequency, wideband, wide-incident-angle, and high-electromagnetic-absorption microwave absorber can potentially be used in aviation, electromagnetic interference (EMI) suppression, and 5G applications.

Features of the behavior of quantum fields in media with a negative refractive index as well as waves with negative energy

In this paper, waves in media with both negative electrical and magnetic permeability and waves of negative energy have been considered together. All conditions have been established under which the propagation of such waves in the corresponding media is possible, taking into account the requirement of the quanta energy positivity. For each of these conditions the direction of the Poynting vector has been established.

Non-continuous curves phenomenon in stressed magneto-electro-elastic plates with negative magnetic permeability

Non-continuous curves phenomenon in stressed magneto-electro-elastic plates with negative magnetic permeability

Enhanced radiation characteristics of regular dodecagon split ring resonator (D-SRR)-based microstrip patch antenna employing dielectric superstrate for THz applications

In a world where communication requires ever faster data transmission capable of transmitting high speeds. In order to reach and transmit this high speed, it is necessary to increase the frequency that carries the information. For this, scientists are interested in the terahertz (THz) range which, thanks to its high frequencies between 0.1 THz and 30 THz, offers the possibility of increasing the data rate. This letter presents the inclusion of Dodecagon Split Ring Resonator (D-SRR) in rectangular microstrip patch antenna and its effect in the performance of the proposed antenna. The metamaterial design employs two types of SRRs resonators shapes such as the Dodecagon Broadside Coupled Split Ring Resonator (DBC-SRR) and Dodecagon Split Ring Resonator (D-SRR). The model applied uses a local field approach and allowed to obtain the dispersion characteristics of discrete negative magnetic permeability. The proposed antenna substrate uses Arlon AD1000 material, which helps to attain high gain and good directivity at THz frequency. The antenna performance is investigated with and without superstrate. The operating frequencies of the proposed antenna vary in the range of 0.66 - 0.69 THz and shows maximum gain of 10.4 dB and maximum directivity of 9.84 dB. HFSS software tool helps to simulate the parametric analysis of the proposed antenna design. This novel structure may find applications in terahertz imaging, remote systems and may find manifold possibilities in the medical field.

Radially Periodic Metasurface Lenses for Magnetic Field Collimation in Resonant Wireless Power Transfer Applications

In this paper, a new procedure and topology of magnetic metasurface lens are proposed for improving the performance of Resonant Wireless Power Transfer systems. Firstly, three subwave-length unit cells are optimized in order to get negative magnetic permeability in the same frequency, each one with a different refractive index, and they are experimentally characterized. Then, the Transformation Optics technique is applied in order to find the unit cell arrangements which lead to the magnetic field focusing in a given direction. For this purpose, two coordinate transformations are proposed, and the effective electric permittivity and permeability that generate these profiles are calculated. It is shown from simulations and measurements that the refractive index gradient produced by the radial disposition of the unit cells can lead to a magnetic field manipulation similar to the optical converging and diverging lenses. Both metamaterials lenses are built, and the calculation of the magnetic flux density as a function of the measured induced voltage in a probe coil verifies their effects on the magnetic field. Finally, their performance in a resonant wireless power transfer system is tested, and improvements in terms of efficiency and range are presented. The proposed design method and the lenses that were developed demonstrate that metasurface lenses can improve efficiency without reducing the range, once these lenses are positioned close to the transmitter coil. Besides that, this method can reduce the losses due to misalignment between coils once the field can be collimated in a specific direction.

Non-continuous furcation phenomenon of SH dispersion curves in magneto-electro-elastic alloy plate with negative magnetic permeability

Inspired by recent work on Lamb waves in magneto-electro-elastic plate (Xiao et al., 2016), in the present work we studied the non-continuous furcation phenomenon of Shear Horizontal (SH) dispersion curves in 40%BaTiO3–60%CoFe2O4 alloy. The SH modes in this magnetostrictive alloy introduce new non-continuous furcation curves that are a remarkable phenomenon when compared to available data. Although (Xiao et al.,2016) did not conclude explicitly the exact and obvious cause of this phenomenon, it seems clear to us that it is closely related to negative magnetic permeability. Even using the negative value of this magnetic permeability, however, the available data is contradictory. Therefore, an investigation into the veracity of the accurate trajectories under this condition was imperative. The obtained observations may serve as a useful reference for the design of ultrasonic transducers for non-destructive evaluation (NDE) in industry.

Using plasmonic cloaking method on infinite cylindrical structures and its applications

In recent years, cloaking using materials with negative electric permittivity or magnetic permeability has been studied and researched. It has been demonstrated that covering an object with a cloak having an electric permittivity or magnetic permeability that is negative or less than unity can cause a reduction of the scattering cross-section (SCS) of the object. In this paper, we solve the scattering problem for an object with a single- or multilayer cylindrical cloak and thus obtain the fundamental equations necessary to design such cloaks under two conditions, viz. with and without consideration of the effects of coupling when solving the scattering problem. Using the obtained equations we demonstrate that this technique can indeed reduce the visibility of the object.

Metallic ferromagnetic selenospinel composites of CuCr2Se4–CdCr2Se4 with double negative electromagnetic parameters

Random metamaterial with negative electric permittivity (ε < 0) and negative magnetic permeability (μ < 0) is a group of attractive alternatives to ordered double negative metamaterials (DNMs) with periodic unit cells; however, the preparation of random DNMs with a relatively convenient preparation process and their electromagnetic property adjustment are of challenge. Here, we report the preparation of metallic ferromagnetic selenospinel composites, xCdCr2Se4·(1−x)CuCr2Se4, from metallic powders by using a simple solid-state reaction process, and double negative ε and μ have been observed in the frequency range of 120–650 MHz for 0.2CdCr2Se4·0.8CuCr2Se4 and 73–520 MHz for 0.4CdCr2Se4·0.6CuCr2Se4. The negative ε is owing to the plasmonic state of delocalized carriers in the metallic ferromagnetic CuCr2Se4, which can be described with the Drude model. The suppression of the magnetic resonance induced by the eddy current has been alleviated by the proper addition of the paramagnetic semiconductor CdCr2Se4. A theoretical model deduced from Maxwell's equation has been constructed based on the skin effect to elucidate the magnetic resonance-dependent negative permeability. Our work introduces the metallic ferromagnetic chalcospinels into the field of random DNMs and sheds light on the theoretical understanding and tuning mechanism on the double negative properties.

All-dielectric bulk isotropic double-negative metamaterials

We propose the design of all-dielectric isotropic micro- or nanoparticles which, when used as structural elements of a metamaterial, can simultaneously provide negative effective electric permittivity and negative magnetic permeability. The particles comprise three dielectric layers with specially adjusted parameters that ensure simultaneous excitation of the electric and magnetic Mie dipole modes. The layer parameters were found by Mie scattering analysis and then verified by the simulations, which confirmed the double-negative behavior of the metamaterial at up to visible light frequencies. The isotropy of such particles suggests the possibility of using them in a double-negative liquid metamaterial.

Controlling negative permittivity and permeability behavior in LaFeO3 through sintering temperature

In this paper, the resonance behavior of LaFeO3 in the GHz range was investigated. Synthesis of LaFeO3, by solid state reaction between Fe2O3 and La2O3, was confirmed by X-ray diffractometry. LaFeO3 exhibited dielectric resonance and magnetic resonance, which can lead to negative permittivity and negative magnetic permeability. By controlling sample synthesis parameters, specifically sintering temperature, the peak in negative permeability can be tuned between 2.6 and 2.8 GHz, while the peak in negative permittivity can be tuned between 0.8 and 1.2 GHz. This material can be applied to fields such as electromagnetic metamaterials, where it could be used to increase the gain of an antenna, or to control the transmission of microwaves.

Simulation Study of Metamaterial Effect towards Ultra Wide Band Antenna

In this paper, the design of a metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. The metamaterial unit cell is constructed using circular split ring resonator (CSRR) technique and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity and attached as superstrate in front of the UWB antenna. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A Rogers (RT5880) substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 0.51 mm, relative permeability of one, relative permittivity of 2.70 and loss tangent of 0.02. The metamaterial antenna is design to be operated at frequency between 300MHz to 30GHz which is suitable for biomedical application such as Microwave Imaging. The overall metamaterial antenna size is 90 mm × 50 mm × 0.51 mm. The design and simulation has been carried out using Computer Simulation Technology Microwave Studio (CST MWS).

Theoretical investigation of magneto-electro-elastic metamaterials

The properties of the multi-field coupling phonon-polaritons in magneto-electro-elastic metamaterials are studied theoretically on the base of the theory of the phonon-polaritons in the piezoelectric superlattices. The mechanism for multi−field coupling is analyzed. We discuss the factors that influence the properties of the multi−field coupling phonon-polaritons. We also study the negative magnetic permeability and negative refraction of the magneto-electro-elastic metamaterial. Some potential applications are also discussed.

Accordable filters by defect modes in single and double negative star waveguides grafted dedicated to electromagnetic communications applications

In the framework of the Green Function approach, we determine the transmission spectrum and the band structure of detective one-dimensional photonic star waveguides. This structure is composed of backbones’ periodicity that is characterized by negative magnetic permeability μ and positive dielectric permittivity ϵ, grafted in each site by resonators of negative permittivity and positive magnetic permeability. In the middle of the structure, we consider geometrical or/and material defect at the backbone level. The presence of such defect in this structure creates inside the photonic band gaps of the perfect structure, very narrow filtered frequencies (defect modes) with a significant quality factor Q and a very high transmission coefficient. The frequencies of the defect modes are strongly sensitive to the variation of the length and the relative permittivity of the defect. These electromagnetic characteristics of the considered structure provide good information for the design of adjustable wide gap filters.

Controlling spins with surface magnon polaritons

Polaritons in metals, semimetals, semiconductors, and polar insulators can allow for extreme confinement of electromagnetic energy, providing many promising opportunities for enhancing typically weak light-matter interactions such as multipolar radiation, multiphoton spontaneous emission, Raman scattering, and material nonlinearities. These extremely confined polaritons are quasielectrostatic in nature, with most of their energy residing in the electric field. As a result, these ``electric'' polaritons are far from optimized for enhancing emission of a magnetic nature, such as spin relaxation, which is typically many orders of magnitude slower than corresponding electric decays. Here, we take concepts of ``electric'' polaritons into magnetic materials, and propose using surface magnon polaritons in negative magnetic permeability materials to strongly enhance spin relaxation in nearby emitters. Specifically, we provide quantitative examples with ${\mathrm{MnF}}_{2}$ and ${\mathrm{FeF}}_{2}$, enhancing spin transitions in the THz spectral range. We find that these magnetic polaritons in 100-nm thin films can be confined to lengths over 10 000 times smaller than the wavelength of a photon at the same frequency, allowing for a surprising 12 orders of magnitude enhancement in magnetic dipole transitions. This takes THz spin-flip transitions, which normally occur at timescales on the order of a year, and forces them to occur at sub-ms timescales. Our results suggest an interesting platform for polaritonics at THz frequencies, and more broadly, a way to use polaritons to control light-matter interactions.

On Plasmon Resonances of a Finite Plate Made from a Metamaterial

Abstract—The article considers the two-dimensional problem of diffraction of a cylindrical wave by a dielectric plate of finite size, the medium of which has simultaneously negative relative dielectric permittivity and relative magnetic permeability. For an electrically thin plate made from such a dielectric (metamaterial), it is shown that the near-field features are related to surface wave (plasmon) resonances. The effect of loss of the medium and the position of the source of a cylindrical polarized TM-wave on plasmon resonances is studied.

Analysis and Optimized Design of Metamaterials for Mid-Range Wireless Power Transfer Using a Class-E RF Power Amplifier

In this paper, a mid-range wireless power transfer (WPT) system based on metamaterials (MMs) has been presented. It has been shown that the MMs are positioned in the WPT system to focalize the electromagnetic field for distance enhancement and efficiency improvement theoretically and experimentally. The MMs were fabricated by using a single layer printed-circuit board (PCB) with the negative magnetic permeability, μr. An applicable impedancetuning technology was implemented by changing the operating distance between the drive (load) resonator and the internal resonator, which can achieve the optimal load of the system. In addition, the Class-E RF (radio frequency) power amplifier is firstly proposed as the high frequency excitation source of the WPT system based on the MMs due to its simple design and high efficiency. The proposed technology can achieve efficiency improvements of 4.26% and 9.13% at distances of 100 cm and 200 cm around the 2.80 MHz WPT system with the MMs, respectively. Specially, it is worth mentioning that the system efficiency is enhanced by 18.58% at 160 cm. The measured results indicate the WPT system based on the MMs can assure a stable output power of 5W at a transfer distance of 200 cm.

Artificial localized magnon resonances in subwavelength meta-particles

The interaction between electromagnetic waves and objects is strongly affected by the shape and material composition of the latter. Artificially created materials, formed by a subwavelength structuring of their unit cells, namely metamaterials, can exhibit peculiar responses to electromagnetic radiation and provide additional powerful degrees of freedom to the scatterer design. In particular, negative material susceptibilities give rise to strong resonant interactions with deeply subwavelength particles. While the negative electrical permittivity of natural noble metals manifests itself in localized plasmon resonant oscillations, negative magnetic permeability materials are rare in nature. Here, the concept of artificial magnon resonance in subwavelength objects with effective negative permeability, designed via the metamaterial approach, is demonstrated. Strong localized oscillations of the magnetic fields within an array of split ring resonators, forming a sphere, hybridize in a collective mode of the structure. As a result, a high scattering cross section, exceeding that of a steel sphere with the same radius by four orders of magnitude, was demonstrated. Scatterers, based on tunable resonances within artificially created materials, can find use in a broad range of electromagnetic applications, including wireless communications, radars, RFID, internet of things hardware, and many others.

Dielectric resonant magnetic dipoles: paradoxes, prospects, and first experiments

We review various forms of dielectric ring-shaped oscillating circuits excited by displacement currents due to the grazing incidence of GHz microwaves. Such circuits with azimuth displacement currents form resonant dielectric magnetic dipoles. We calculate and measure resonances in field spectra in the near zone of such dipoles. We demonstrate the inversion of the magnetic inductance flux and the formation of a negative magnetic permeability in the resonant range of dielectric magnetic dipoles. We also investigate, both analytically and experimentally, the resonant interaction spectra of a pair of magnetic dipoles excited by displacement currents. Finally, prospects for using these dipoles to model all-dielectric nanostructures with alternating-sign magnetic permeability are discussed.