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The design of a circuit to transmit contactless data between two stacked chips is presented in this brief. The communication is performed through magnetic coupling of a pair of inductors, where the primary and secondary inductors are integrated into the transmitter and receiver chips, respectively. The series decoupling capacitor topology is chosen due to the absence of static power consumption. The dynamic characteristics of the topology are properly equated to identify the design trade-offs. Also, the performance metrics for the transmitter circuit are defined. Considering those metrics and the analysis of the topology, a design methodology is proposed. The transmitter implemented in CMOS 180nm technology supports a 5Gbps data rate and consumes 1.3pJ/bit when verified in simulations.

This paper presents the design and analysis of four types of dual-band resonance inductive coupling architecture for wireless power transfer (WPT) and near-field communication (NFC) applications, respectively SS, SP, PS, and PP. These four types of architecture are composed of LC series (LC branch) and LC parallel (LC tank). For example, the first S of SP means that the primary side circuit uses an LC branch in series with the LC tank, and the second P of SP means that the secondary side circuit uses an LC tank in parallel with the LC branch. This design sets the dual-band inductive coupling frequencies at 6.78MHz and 13.56MHz, respectively. Next, consider the load effect caused by the magnetic coupling between the two coils and compensate for it on the primary side of the coil. In addition, this paper also proposes four types of design guidelines through theoretical analysis. These design guidelines can be uses to determine the inductance value and capacitance value of the LC-branch and LC-tank on the primary and secondary sides, respectively. Finally, the simulation and measurement results are in agreement with design guidelines. That will be very valuable in future practical applications.

In recent years, two-dimensional (2D) magnetic heterostructures have captured widespread interest as they provide a fertile ground for exploring the novel properties induced by interfacial magnetic coupling, modulating the intrinsic magnetism of the 2D magnet, and exploiting new spintronic device applications. In this Spotlight on Applications, dominating synthetic strategies employed to fabricate 2D magnetic heterostructures are introduced first. Notably, we then concentrate on two different kinds of magnetic interfaces, namely, the magnetic-nonmagnetic interface and the magnetic-magnetic interface. Specifically, various interface modulated magnetisms such as valley splitting and the anomalous Hall effect as well as their related device applications such as magnetic tunnel junctions have been further reviewed and discussed. Finally, we briefly summarize the recent progress of 2D magnetic heterostructures and outline the future development direction of this booming field.

Magnetic polar materials feature an astonishing range of physical properties, such as magnetoelectric coupling, chiral spin textures, and related new spin topology physics. This is primarily attributable to their lack of space inversion symmetry in conjunction with unpaired electrons, potentially facilitating an asymmetric Dzyaloshinskii-Moriya (DM) exchange interaction supported by spin-orbital and electron-lattice coupling. However, engineering the appropriate ensemble of coupled degrees of freedom necessary for enhanced DM exchange has remained elusive for polar magnets. Here, we study how spin and orbital components influence the capability of promoting the magnetic interaction by studying two magnetic polar materials, α-Cu(IO3)2 (2D) and Mn(IO3)2 (6S), and connecting their electronic and magnetic properties with their structures. The chemically controlled low-temperature synthesis of these complexes resulted in pure polycrystalline samples, providing a viable pathway to prepare bulk forms of transition-metal iodates. Rietveld refinements of the powder synchrotron X-ray diffraction data reveal that these materials exhibit different crystal structures but crystallize in the same polar and chiral P21 space group, giving rise to an electric polarization along the b-axis direction. The presence and absence of an evident phase transition to a possible topologically distinct state observed in α-Cu(IO3)2 and Mn(IO3)2, respectively, imply the important role of spin-orbit coupling. Neutron diffraction experiments reveal helpful insights into the magnetic ground state of these materials. While the long-wavelength incommensurability of α-Cu(IO3)2 is in harmony with sizable asymmetric DM interaction and low dimensionality of the electronic structure, the commensurate stripe AFM ground state of Mn(IO3)2 is attributed to negligible DM exchange and isotropic orbital overlapping. The work demonstrates connections between combined spin and orbital effects, magnetic coupling dimensionality, and DM exchange, providing a worthwhile approach for tuning asymmetric interaction, which promotes evolution of topologically distinct spin phases.

Metal magnetic memory (MMM) is a widely used non-destructive electromagnetic detection technology. However, the analysis of its underlying principle is still insufficient. The mechanical and magnetic coupling model is a reasonable standpoint from which to study the principle of MMM. In this paper, a mechanical and magnetic coupling model of steel material is established based on density functional theory (DFT) using the CASTEP first-principles analysis software. In order to simulate the practical working environment, the residual magnetism in the rail is assumed to change with the stress on the rail. By applying different stresses to the model, the relationship between the atomic magnetic moment, the lattice constant and stress is explored, as well as the causes of magnetic signals in the stress concentration zone. It is revealed that the atomic magnetic moment and the crystal volume decrease with the increase in compressive stress. The magnetic signal on the surface of the magnetised metal component decreases with the increase in compressive stress, while the tensile stress shows the opposite tendency. Generally speaking, the change in atomic magnetic moment and crystal volume caused by lattice distortion under stress can be seen as the fundamental reason for the change in magnetic signal on the surface of the magnetised metal. The bending experiment of the rail shows that the normal magnetic field decreases with the increase in compressive stress in the stress concentration zone. The conclusion is verified by experiments.

Lightweight and high-performance are two determining factors for metal-organic-frameworks (MOFs) derived microwave absorbers. However, most of the reported MOFs derived absorbers usually possess high filler loading. Herein, a series of MOFs derived magnetic porous carbon microspheres with tunable diameter and high specific surface area have been synthesized via a pyrolysis process. The synthesized magnetic porous carbon microspheres, constructed by uniformly distributed core-shell Ni@C, exhibit high-performance microwave absorption with a low filler loading of 10 wt%. Considering the mciro-mesoporous structures, matched impedance, strong conductive loss, enhanced dipolar/interfacial polarization as well as strong magnetic coupling network, a minimum reflection loss of -60 dB and an absorption bandwidth of 7.0 GHz can be achieved at 2.6 mm. Moreover, the bandwidth reaches as wide as 10.2 GHz when the thickness is 4 mm. In addition, compared with other MOFs derived absorbers, this work provides us a simple strategy for the synthesis of porous carbon microspheres with lightweight and high-performance microwave absorption for practical applications.

The undesirable absorption bandwidth is the main limitation for the application of microwave absorbing materials. Noting that the design of structure and composition of absorbing coating allows it to obtain a satisfying absorption bandwidth and to avoid weight increasing, honeycomb and its sandwich structures coated by various absorbant have been developed and measured using an arch measurement system over 2−18 GHz. To further understand the absorption mechanisms of honeycomb structural materials, simulation based on finite element method and transmission line theory is performed to analyze the different responses to the applied microwave between honeycomb structural materials and uniform-medium slab materials. The proper composition design allows control over the microwave loss mechanisms, which optimize the coating to possess both of the dielectric and magnetic advantages. For the honeycomb structural materials, the magnetic resonation is found for the first time, which is resulting from the periodic honeycomb walls on both sides of the dielectric cavity (consisting of the aramid paper interlayer and vacuum hexagonal prisms). In addition, the conversion of structure from solid to honeycomb brings about changes in impedance, propagating path, effective wavelength, effective attenuation area, microwave phases, and inductive coupling effect, etc., which result in a better microwave absorbing performance. The honeycomb sandwich structure coated by CIP/CB/EP with the weight ratio of 4:0.03:1 shows the absorption bandwidth of ∼9.8 GHz for reflection loss (RL) lower than -10 dB which covers part of the S and C bands and almost the whole X and Ku bands.

An electrically small three-dimensional (3-D) antenna is proposed to generate a quasi-isotropic radiation pattern. The proposed antenna consists of a single layer conductor with bilateral symmetrical structure before being wrapped in a cylindrical foam. An H-shaped inductive coupling element is used to feed the antenna to obtain a magnetic dipole and a pair of short electric dipoles after the antenna is wrapped in a cylindrical foam. Therefore, by combining orthogonal complementary dipoles with the same radiation intensity and quadrature phase difference, a quasi-isotropic radiation pattern can be obtained. As a proof of this design, a 3-D antenna structure operating at 2.45 GHz is designed, fabricated and measured. It has been shown that the gain variation of the proposed electrically small antenna (ka = 0.48) in total space is 2.72 dB in simulation and 3.53 dB in measurement.

We report an experimental study of the bimagnetic nanocomposites CoFe2/CoFe2O4. The precursor material, CoFe2O4 was prepared using the conventional stoichiometric combustion method. The nano-structured material CoFe2/CoFe2O4 was obtained by total oxygen reduction of CoFe2O4 using a thermal treatment at 350 °C in H2 atmospheres following the partial oxidation in O2 atmospheres at 380 °C during 120; 30; 15, 10, and 5 min. The X-ray diffraction, Mössbauer spectroscopy and transmission electronic microscopy images confirmed the formation of the material CoFe2/CoFe2O4. The magnetic hysteresis for the nanocomposite with different saturation magnetization (from 87 to 108 emu/g) also confirms the formation of the CoFe2/CoFe2O4 with different content of CoFe2O4. Furthermore, the magnetic hysteresis curves for all samples presented a single magnetic behavior, suggesting the magnetic coupling between the phases of the nanocomposite. The effects of high energy milling on the magnetic properties of the precursor material and nanocomposites samples were evaluated.

Electronic and magnetic coupling through nonalternant π-systems is an area of intense interest in photonics and molecular electronics research, yet relatively little is known regarding coupling through nonalternant π-systems. Herein we present magnetic exchange coupling in two semiquinone-based biradicals: 1,3-SQ2Fc has two semiquinone radicals attached to the one- and three-positions of the same cyclopentadienyl ligand (a nonalternant π-system) of ferrocene, whereas 1,1'-SQ2Fc has one semiquinone radical attached to each of the two cyclopentadienyl ligands of ferrocene.

The advance in communication technology has triggered worldwide concern on electromagnetic wave pollution. To cope with this challenge, exploring high-performance electromagnetic (EM) wave absorbing materials with dielectric and magnetic losses coupling is urgently required. Of the EM wave absorbers, transition metal diborides (TMB2) possess excellent dielectric loss capability. However, akin to other single dielectric materials, poor impedance match leads to inferior performance. High-entropy engineering is expected to be effective in tailoring the balance between dielectric and magnetic losses through compositional design. Herein, three HE TMB2 powders with nominal equimolar TM including HE TMB2-1 (TM = Zr, Hf, Nb, Ta), HE TMB2-2 (TM = Ti, Zr, Hf, Nb, Ta), and HE TMB2-3 (TM = Cr, Zr, Hf, Nb, Ta) have been designed and prepared by one-step boro/carbothermal reduction. As a result of synergistic effects of strong attenuation capability and impedance match, HE TMB2-1 shows much improved performance with the optimal minimum reflection loss (RLmin) of −59.6 dB (8.48 GHz, 2.68 mm) and effective absorption bandwidth (EAB) of 7.6 GHz (2.3 mm). Most impressively, incorporating Cr in HE TMB2-3 greatly improves the impedance match over 1–18 GHz, thus achieving the RLmin of −56.2 dB (8.48 GHz, 2.63 mm) and the EAB of 11.0 GHz (2.2 mm), which is superior to most other EM wave absorbing materials. This work reveals that constructing high-entropy compounds, especially by incorporating magnetic elements, is effectual in tailoring the impedance match for highly conductive compounds, i.e., tuning electrical conductivity and boosting magnetic loss to realize highly efficient and broadband EM wave absorption with dielectric and magnetic coupling in single-phase materials.

Inducing magnetic coupling between 4f elements is an ongoing challenge. To overcome this formidable difficulty, we incorporate highly delocalized tetrazinyl radicals, which strongly couple with f-block metallocenes to form discrete tetranuclear complexes. Synthesis, structure, and magnetic properties of two tetranuclear [(Cp*2 Ln)4 (tz. )4 ]⋅3(C6 H6 ) (Cp*=pentamethylcyclopentadienyl; tz=1,2,4,5-tetrazine; Ln=Dy, Gd) complexes are reported. An in-depth examination of their magnetic properties through magnetic susceptibility measurements as well as computational studies support a highly sought-after radical-induced "giant-spin" model. Strong exchange interactions between the LnIII ions and tz. radicals lead to a strong magnet-like behaviour in this molecular magnet with a large coercive field of 30 kOe.

Endowing bilayer transition-metal dichalcogenides (TMDs) with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom (DOFs). However, effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges. Herein, we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion, by introducing sulfur vacancy (VS) to modulate the interlayer electronic coupling. This strategy could transform the interlayer exchange interaction from antiferromagnetism (AFM) to ferromagnetism (FM), as revealed by the magnetic measurements. Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and VS-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers, and also enhances the intralayer FM. Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional (2D) magnetic materials.

We used helical antenna-coupled radio frequency (RF) plasmas to study the evolution of the mode transition power and electron kinetics under different applied magnetic fields and argon pressures. Langmuir probe and emission spectrum data indicate that the discharge mode changes from the capacitive coupling E mode to the inductive coupling H mode through a strong mixed mode (E + H). One reason for this strongly mixed ionization is the antenna structure, which increases the capacitive coupling. Furthermore, the $\text{E}\to \text{H}$ transition threshold power decreases with increasing pressure regardless of whether there is a magnetic field, and the presence of the magnetic field significantly increases the transition power. The electron energy distribution function (EEDF) curve has a Druyvesteyn shape at low RF power (E mode). The presence of a magnetic field increases the electron energy range, and the binding of the electrons by the magnetic field causes the EEDF to deviate significantly from the Maxwellian shape. As RF power increases, the EEDF tends toward the Maxwellian shape during the transition from the E mode to the H mode. The magnetic field appears to act like a drag on this process, particularly at very low pressures.

In magnetic coupling resonant wireless power transfer devices, planar spiral coils are often used as the coupling mechanism. In such application area, the coils are often wound sparsely with wide screw pitches and often under complex relative position. An accurate model of mutual inductance for planar spiral coils wound either densely or sparsely is established in this article. Utilizing Euler Angles, an exact expression of mutual inductance for a couple of planar spiral coils under arbitrary relative position is proposed. Based on this expression and geometric mean distance principle, a self-inductance expression for planar spiral coils is derived. Based on numerical calculation of the expressions proposed in this article, the influence of precession and spin angle on mutual inductance is studied; the method of determining radius of each turn when using traditional concentric circular filaments cluster approximation model for self- and mutual inductance calculation is studied; the difference of calculation results between the accurate model and the traditional approximation model is compared. Finite element simulation and experimental results verify the correctness of the proposed models.

This article presents an improved equivalent-circuit model for millimeter-wave six-port transformers on silicon with accurate coupling factor modeling. The lossy silicon substrate eddy current effects have a significant impact on the mutual resistive coupling factor ( $k_{\mathrm {re}}$ ) of the primary and secondary coils, which in turn affects the maximum available gain ( $G_{\mathrm {max}}$ ) of the transformer. To characterize eddy currents’ loss in the silicon substrate, “effective substrate current loops,” which are magnetically coupled by the primary and secondary coils simultaneously, are presented. The mutual inductances and coupling capacitances are used to model coupling effects between all segments of the coils. The proposed model can accurately predict the frequency-dependent mutual reactive coupling factor ( $k_{\mathrm {im}}$ ) and mutual resistive coupling factor ( $k_{\mathrm {re}}$ ). A corresponding methodology to parameter extraction based on electromagnetic (EM) simulations is demonstrated. A two-way current-combining-based power amplifier (PA) is presented for fifth-generation (5G) communication in the 65-nm CMOS process. Using the developed transformer model, the baluns and inter-stage transformers in the PA are modeled and analyzed. The power gain of the PA is 22.8 dB, the saturated output power ( $P_{\mathrm {sat}}$ ) is 18.7 dBm, and the power-added efficiency (PAE) is 21.88%.

Recent developments, in the field of wireless charging, have led to increasing use of this technology across different areas of research. The search for improvement in Soldier Combat Systems has seen major investments in recent years, to find a standard architecture that can enhance military capabilities, such as in power management systems. This work is part of the C4I program of the Portuguese army, having had the primary objective of studying an alternative power supply option based on wireless technology, capable of charging man-portable devices in military vehicles. On this dissertation, it was conducted a study on the behavior of the components of a wireless power transfer, focusing on different configurations and geometries of the charging coils, as well as the optimization of key parameters in a wireless power module. For this, key operating principles and charging methods were approached. Using distance as a variable parameter, it was possible to study the variation in signal amplitude and compare the performances of each coil, reaching promising conclusions on which coil geometry is best suited in terms of shape, reach, and intensity of the generated magnetic field of the power transfer. Also, the matching outcomes from the theoretical deductions and the experimental work done in a controlled environment led to a strengthening of the obtained results. After fabricating and testing prototype 3D structures for the coils, a proposal for a wireless charging system was conceived. This proposal includes architecture, protocols, and its implementation taking into account the characteristics of the charging environment.

This paper investigates the effect of frequency on the magnetic field (H-field) strength at a specified distance from a single turn transmitting (TX) loop antenna in free-space. The H-field of a TX loop antenna in the Near Field (NF) region can be estimated using Biot-Savartâ s Law (BSL). However, the BSL method is only valid for DC current flow and does not consider the effects of frequency on the H-field strength. This work introduces the frequency-dependent Antenna Near Field (ANF) method reported in the literature and compares this method against the BSL method and EM simulation results. It is shown that the ANF method can estimate the H-field magnitude with an error of less than 5% when compared with finite-element methods (FEM). In addition, the ANF method computes in a fraction of a second, whereas the FEM method takes several minutes to compute.

With the continuous development of information technology, the performance of the entire traditional electrical system is gradually optimized. Nowadays, the single-chip technology is an important part of the traditional electrical system because it determines the operating quality of the entire traditional system. However, due to the electromagnetic pulse, the single-chip microcomputer system may be interfered with malfunction or damage, which seriously affects its performance. Therefore, to investigate the impact of an electromagnetic pulse on a single-chip microcomputer system, in this research work, we have used a STM32 single-chip microcomputer as the research object by setting up multiple sets of STM32 single-chip microcomputer serial communication systems. Besides, we have conducted an electromagnetic pulse vulnerability experiment using the inductive coupling inject method which has improved the antielectromagnetic pulse capacity of the STM32 single-chip serial communication system. The experimental results show that the damage threshold of the single-chip microcomputer with positive pulse injection is greater than the negative pulse injection, which indicates that the serial communication system of the STM32 single-chip microcomputer is more sensitive to the negative pulse injection. Moreover, this research work is of great significance to evaluate more accurately the viability and anti-interference capability of a single-chip microcomputer system under the action of electromagnetic pulse.

In this article, a nonlinear piezoelectric harvester coupled with a standard rectifying circuit is developed. Contrary to traditional Duffing-type magnetic harvester mechanism, the nonlinear effect...

The most detailed, first-principle simulation model of a quench in a high-temperature superconducting metal-insulation multi-module/multi-double-pancake coil, wound with a REBCO coated superconductor/tape and normal-metal tape (co-wind), was developed. It enables one to simulate a normal zone propagation, or non-propagation, in the subtle multi-turn structure of the coil's pancakes due to the inductive coupling and transverse electric contact between all the REBCO turns and co-wind turns along with the external circuit and active and passive quench protection systems. In doing so, the multi-module coil's structure is represented as a “rectilinear equivalent” electric circuit, a branched multi-decker multi-rectangle planar grid, which facilitates the mathematical formulation, using the standard electric circuit differential equations and the Kirchhoff's rules. The transient non-linear comprehensive heat conduction equations are employed to model the thermal part of the phenomenon at the same level of detail. All this turns the model into an effective design tool for metal-insulated, -stabilized and/or -reinforced multi-module coils. A parametric study of quench in a 6-module no-insulation (NI) test coil, using a stainless-steel thin co-wind, was conducted to identify the possibilities of the model. The profound effect of the transverse contact resistivity on an NI-coil quench behavior is confirmed and detailed.

Three-phase transformer type superconducting fault current limiter (SFCL) using two common connection points between secondary windings, which consisted of three-phase transformer windings wound on three legs of E-I iron core and two/three superconducting modules (SCMs), were suggested and its fault current limiting operations according to ground-fault types were analyzed. To verify the effective operation of the three-phase transformer type SFCL using two common connection points between secondary windings, the unsymmetrical ground and the symmetrical ground faults were applied into three-phase power simulated system with the suggested SFCL. For the comparison, the ground faults were generated into three-phase transformer type SFCL with two/three SCMs. Through analysis on the test results, the SFCL with two SCMs was confirmed to have no different fault current limiting operation from the SFCL with three SCMs. The structure of E-I iron core with three magnetically coupled legs and the constitution of three secondary windings with two common connection points were analyzed to be contributed to the same fault current limiting operation. Furthermore, the power consumption and the joule energy of the SCMs comprising both the SFCL with two SCMs and the SFCL with three SCMs during the fault period had shown to be almost the same except for the transient period due to the quench time difference in case of the single-line ground fault.

The output characteristic of an inductive power transfer (IPT) system is highly susceptible to variations in magnetic coupling. In this article, a primary-side X-type compensation topology is proposed to acquire stable output characteristics against a wide range of magnetic coupling without resorting to tight control and coil design. By introducing the concept and derivation principle for the coupling-insensitive compensation topologies, the X-type network is presented to provide self-regulation ability for primary coil current against variable coupling, thereby enabling steady power transfer in a highly dynamic environment. The design considerations for the passive parameters are elaborated, followed by the comparison with regular compensation methods. Owing to its unique structure and design flexibility, the X-type compensation exhibits a stable output characteristic that is beneficial in enhancing the tolerance to position shifts. Moreover, it also features a wide soft-switching range and more flexible design for the output level range than previous topologies. Experimental results show stable power transfer over a coupling factor of 0.14–0.28, where the power fluctuation is less than 20%. The presented method is seen as a potential solution for low power IPT systems, where high mobility is demanded.

The design and fabrication of anisotropic photonic crystal supraballs with multiple responses are highly desirable for versatile environmental sensing and flexible displaying. Herein, we developed an available strategy to construct a series of multi-responsive magnetic colloidal photonic crystal (CPC) supraballs with Janus and molecular-analogue structures. Initially, the humidity and temperature sensitive CPC supraballs were obtained via immobilization of polyacrylamide (PAM) and polyisopropylacrylamide (PNIPAM) hydrogels into the CPC structure, respectively, and CdTe/ZnS quantum dots endow the supraballs fluorescent signal under UV light. Furthermore, Fe3O4 nanoparticles (NPs) were served as a magnetic hemisphere to construct CPC Janus supraballs which can be subsequently assembled into three different molecular-shaped cluster particles that integrate more response types via Fe3O4 NPs hemisphere coalescence to a magnetic coupling center, recognizing multiple responses simultaneously that correspond the environmental altering. In addition, 2D polychromatic patterns with sensitive CPC pixels printed by automatic printing system were demonstrated, which could monitor the changes of temperature and humidity. The multi-responsive magnetic controlling supraballs and 2D patterns reveal the promising applications in environmental sensing, anti-counterfeiting and displaying.

One-dimensional zigzag cyanido-bridged coordination polymers have been prepared as a result of self-assembly of lanthanide(III) ions with octacyanidotungstate(V) anions in the presence of N,N-dimethylacetamide (dma). All compounds crystallized in noncentrosymmetric space group P21 with a molecular formula of [LnIII(dma)5][WV(CN)8] [Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5), Tm (6), Yb (7), Lu (8), or Y (9)]. Magnetic studies revealed weak antiferromagnetic interactions through LnIII-NC-WV bridges and the formation of ferrimagnetically coupled chains at very low temperatures. Moreover, temperature dependencies of magnetic susceptibilities were fitted using the crystal field parameters for Ln(III) ions, determined by the ab initio calculations, yielding magnetic coupling constants in the range of -1 to -5 cm-1. The wide optical transparency of 1-9 has been determined using solid state absorption spectroscopy. Samples exhibited second harmonic (SH) generation properties with SH susceptibilities ranging from 4.7 × 10-12 to 9.4 × 10-11 esu due to the presence of nonlinear optical susceptibility tensor elements (χijk) χzxx, χzyy, χzzz, χzxy, χyyz, χyzx, χxyz, and χxzx, corresponding to space group P21. The determined values were also compared with the results of theoretical calculations and previous reports, indicating a potential relationship between the type of lanthanide ion and the SH intensity.

A mechanical device which raises the pressure of a gas by decreasing its volume is called as compressor. A coupling is a device which transmits the power from one end to another end. The purpose of coupling is to join two parts which allowing some degree of misalignment or end movement or both. But in conventional coupling, there are lots of losses like mechanical losses, noise and vibration losses etc. These losses have effects on the efficiency of the system. In mechanical seals, leakages are possible. So, leakage of hazardous chemicals polluting the environment has to prevent. The mechanical seal limits the speed of the compressor as the wear rates of the seal are proportional to speed. To improve the efficiency of coupling and to minimize the mechanical losses of coupling, magnetic coupling is introduced. It is contactless coupling which transfer the power from input shaft to output shaft. MATLAB software is used for analysis of magnetic coupling. This paper represents evaluation of force and torque transmitted by magnetic coupling. The theoretical analysis of magnetic coupling is carried out by using basic principle of electromagnetism. Magnetic coupling is designed to sustain the given load and torque. Permanent disc magnets of NdFeB material are selected for magnetic coupling for high strength of magnetic field. The brass plates are used to hold the magnets.

Room temperature two-dimensional (2D) ferromagnetism is highly desired in practical spintronics applications. Recently, 1T phase CrTe2 (1T-CrTe2) nanosheets with 5 and thicker layers have been successfully synthesized, which all exhibit the properties of ferromagnetic (FM) metals with Curie temperatures around 305 K. However, whether the ferromagnetism therein can be maintained when continuously reducing the nanosheet's thickness to monolayer limit remains unknown. Here, through first-principles calculations, we explore the evolution of magnetic properties of 1 to 6 layer CrTe2 nanosheets and several interesting points are found: First, unexpectedly, monolayer CrTe2 prefers a zigzag antiferromagnetic (AFM) state with its energy much lower than that of FM state. Second, in 2 to 4 layer CrTe2, both the intralayer and interlayer magnetic coupling are AFM. Last, when the number of layers is equal to or greater than 5, the intralayer and interlayer magnetic coupling become FM. Such highly thickness dependent magnetism provides a new perspective to control the magnetic properties of 2D materials.

The magnetic coupling of filter inductors is widely utilized in various power electronics application fields, including most commonly implemented dc-dc converters in electric vehicle charger systems, in order to enhance the filtering performance while maintaining the minimal filter size. The optimal distribution of self and mutual inductance of the coupled inductor is regarded as one of the important design tasks with respect to the coupling factor. This article proposes an explicit mathematical form of the optimized coupling factor design of a generalized n -winding coupled inductor, which generates the least size of inductor current ripple in phase-staggered multiparalleled dc-dc converters. The general equations for the n -winding coupled inductor are verified through the example case of the three-winding coupled inductor. The experimental results successfully confirmed the newly proposed method of obtaining the optimal coupling factor.

We describe efficient four-coil inductive power transfer (IPT) systems that operate at 100 MHz. The magnetically-coupled transmitter and receiver were made from electrically-small and high-Q loop-gap resonators (LGRs). In contrast to the commonly-used helical and spiral resonators, the LGR design has the distinct advantage that electric fields are strongly confined to the capacitive gap of the resonator. With negligible fringing electric fields in the surrounding space, the IPT system is immune to interference from nearby dielectric objects, even when they are in close proximity to the transmitter and/or receiver. We experimented with both cylindrical and split-toroidal LGR geometries. Although both systems performed well under laboratory conditions, the toroidal geometry has the additional advantage that the magnetic flux is weak everywhere except within the bore of the LGR and in the space directly between the transmitter and receiver. Furthermore, we show that the toroidal LGR system can be operated efficiently at a fixed frequency for a wide range of transmitter-receiver distances. The experimental results are complimented by 3-D finite-element simulations which were used to investigate the electromagnetic field profiles and surface current density distributions. Finally, we demonstrate the use of our IPT system at powers up to 32 W and discuss possible applications., Comment: 18 pages, 12 figures

This paper introduces a new DC–DC structure with a high voltage gain. The proposed structure can achieve higher voltage gain by using magnetic coupling and voltage multiplier circuit (VMC). The VMC is also used as a clamp circuit to suppress the voltage spike through the switch which leads to increase the overall system efficiency. Moreover, the peak voltage through the semiconductors of the proposed converter is low. The existence of soft‐switching such as zero‐current switching (ZCS) in OFF‐state and zero‐voltage switching (ZVS) in ON‐state of diodes is another merit of the proposed converter. The recommended structure uses one power MOSFET with low on‐state resistance (RDS‐ON) that leads to decrease the conduction loss. For demonstrating the proficiency of the proposed structure, technical analysis, mathematical survey, and comparison results with other similar previous structures are carried out. Finally, laboratory results with 200 W output power and 50 kHz switching frequency are provided, which prove the usefulness of the suggested converter. The proposed converter's efficiency in 200 W output power is 96.98 %. Also, the voltage gain, maximum voltage stress across the power switch and didoes for n (turn‐ratio) = 2 and D (duty‐cycle) = 0.6 are equal to 10, 0.25, and 0.75, respectively.

To maintain a stable output voltage under various operating conditions without introducing extra dc/dc converters, phase-shift (PS) control is usually adopted for wireless power transfer (WPT) systems. By using this method, however, zero-voltage switching (ZVS) operation cannot be guaranteed, especially in light-load conditions. To achieve high efficiency and reduce electromagnetic interference, it is significant for WPT systems to achieve ZVS operation of all switching devices in the whole operation range. In this article, an auxiliary variable inductor, of which the equivalent inductance can be controlled by adjusting the dc current in its auxiliary winding, is designed for series–series-compensated WPT systems under PS control to mitigate the loss arising from hard switching. As a result, a wide ZVS operation range of all switching devices can be achieved. A laboratory prototype is built to verify the theoretical analysis. The experimental results show that, under load and magnetic coupling variations, ZVS operation at fixed operation frequency as well as a constant dc output voltage can be maintained. Compared to the conventional method with only PS control, the proposed WPT can achieve higher overall efficiency in a wider load range owing to the wide ZVS operation range.

Currently, a large number of neurostimulators are commercially available for the treatment of drug-resistant diseases and as an alternative to pharmaceuticals. According to the current state of the art, such highly engineered electroceuticals require bulky battery units and necessitate the use of leads and extensions to connect the implantable electronic device to the stimulation electrodes. The battery life and the use of wired electrodes constrain the long-term use of such implantable systems. Furthermore, for therapeutic success and patient safety, it is of utmost importance to keep the stimulation current within a safe range. In this paper, we propose an implantable system design that consists of a low number of passive electronic components and does not require a battery. The stimulation parameters and power are transmitted inductively using an extracorporeal wearable transmitter at frequencies below 1 MHz. A simple circuit design approach is presented to achieve a closed-loop control of the stimulation current by exploiting the nonlinear properties of ferroelectric materials in ceramic capacitors. Twenty circuit topologies of series- and/or parallel-connected ceramic capacitors are investigated by measurement and are modeled in Mathcad. An approximately linear increase in the stimulation current, a stabilization of the stimulation current and an unstable state of the system were observed. In contrast to previous results, specific plateau ranges of the stimulation current can be set by the investigated circuit topologies. For further investigations, the consistency of the proposed model needs to be improved for higher induced voltage ranges.

Multiple-receiver resonant inductive coupling wireless power transfer (RIC-WPT) technique is emerging as a promising charging method for multiple household appliances, mobile devices, and wearable devices. However, this technique often suffers from output power fluctuation owing to the cross-interference among receivers as well as the manufacturing and aging tolerance of the resonant frequency (i.e., resonant frequency tolerance). This article proposes an autonomous RIC-WPT system concept to solve this difficulty. The proposed concept addresses the cross-interference and resonant frequency tolerance by incorporating the following two functions. First, the amplitude of the transmitter current is controlled to have a constant amplitude. Second, the phase of each receiver current is controlled to be orthogonal to that of the transmitter current by using an active reactance compensator installed in each receiver. The experiment of a two-receiver RIC-WPT system successfully verified that the two functions of the proposed system concept can stabilize the output voltage against the cross-interference and resonant frequency tolerance.

Magnetic memory testing is a new nondestructive testing technology, which can detect the early damage of ferromagnetic components such as stress concentration. In this paper, the coupling model between the stress of ferromagnetic material and its magnetic leakage field is established. In this model, the relative change rate of permeability of ferromagnetic material is proportional to the stress, the change of permeability and the saturation magnetic induction. The experimental results show that the model can well describe the relationship between stress and leakage magnetic field.

Multiferroic oxide heterostructures consisting of ferromagnetic and ferroelectric components hold the promise for nonvolatile magnetic control via ferroelectric polarization, advantageous for the low-dissipation spintronics. Modern understanding of the magnetoelectric coupling in these systems involves structural, orbital, and magnetic reconstructions at interfaces. Previous works have long proposed polarization-dependent interfacial magnetic structures; however, direct evidence is still missing, which requires advanced characterization tools with near-atomic-scale spatial resolutions. Here, extensive polarized neutron reflectometry (PNR) studies have determined the magnetic depth profiles of PbZr0.2Ti0.8O3/La0.67Sr0.33MnO3 (PZT/LSMO) bilayers with opposite self-polarizations. When the LSMO is 2-3 nm thick, the bilayers show two magnetic transitions on cooling. However, temperature-dependent magnetization is different below the lower-temperature transition for opposite polarizations. PNR finds that the LSMO splits into two magnetic sublayers, but the inter-sublayer magnetic couplings are of opposite signs for the two polarizations. Near-edge X-ray absorption spectroscopy further shows contrasts in both the Mn valences and the Mn-O bond anisotropy between the two polarizations. This work completes the puzzle for the magnetoelectric coupling model at the PZT/LSMO interface, showing a synergic interplay among multiple degrees of freedom toward emergent functionalities at complex oxide interfaces.

We present a study on the nuclear and magnetic structures of two iron-based garnets with magnetic cations isolated on tetrahedral sites. Ca\(_2\)YZr\(_2\)Fe\(_3\)O\(_{12}\) and Ca\(_2\)LaZr\(_2\)Fe\(_3\)O\(_{12}\) offer an interesting comparison for examining the effect of increasing cation size within the diamagnetic backbone of the garnet crystal structure, and how such changes affect the magnetic order. Despite both systems exhibiting well-pronounced magnetic transitions at low temperatures, we also find evidence for diffuse magnetic scattering due to a competition between the nearest-neighbor, next nearest-neighbor, and so on, within the tetrahedral sites. This competition results in a complex noncollinear magnetic structure on the tetrahedral sublattice creating a mixture of ferro- and antiferromagnetic interactions above the long-range ordering temperature near 20 K and suggests that the cubic site of the garnet plays a significant role in mediating the superexchange interactions between tetrahedral cations.

In this brief, a novel differential-mode (DM) interference propagation mathematical modeling method based on parasitic inductive coupling theory for SiC wirebond multichip power module (SWMPM) with adjacent decoupling capacitor is proposed. Based on the proposed model, the strong and weak inductive coupling theory of DM interference equivalent circuit is proposed. And the influence of different position of decoupling capacitors on DM equivalent current is mathematically analyzed. A custom-made 1.2kV 160A power module based on DM interference optimized layout is built. It is compared with a commercial SiC power module, which can verify the feasibility and validity of the theoretical analysis.

Buried metallic pipelines are used to transmit the natural gas and petroleum products to the citizens. Sometimes these pipelines are constructed in the same pathway of the overhead transmission lines (OHTLs) to save the additional right-of-way cost, and to avoid the destruction of agricultural lands. AC voltage is induced on these pipelines by the power lines electric and magnetic fields. There are many mechanisms that describe the AC voltage inducing on these pipelines; capacitive coupling describes the pipelines induced voltage by the power lines electric field, inductive coupling characterizes the induced voltage caused by the OHTLs electromagnetic fields and conductive coupling is created in buried pipelines near to OHTLs by earth fault current. In the present paper the induced voltages of pipelines created by OHTLs due to the different couplings are investigated in normal condition of operation as well as line to ground fault. The current of the coating discharging and AC corrosion are investigated. The induced overvoltage appears on the natural gas pipeline is measured in steady state condition of the transmission circuits operation. Moreover, this paper represents the mitigation of the induced voltages by using two different KOH-PCs systems.

To improve the misalignment tolerance for inductive power transfer (IPT) systems in implantable medical devices, like retinal prosthesis, a 3-D through silicon via (TSV) based orthogonal receiving coil is proposed in this brief. The mutual inductance between the receiving coil and the transmitting coil is calculated, analyzed, and compared. Results obtained from the analytical model and finite element method show the proposed coil structure significantly enhances the inductive coupling between coils under misalignment. Furthermore, we present receiving circuits with current summing techniques to enhance the energy transfer between the receiving coil to the load. The prototype of the inductive power transfer system is developed and the experimental results demonstrate that the proposed coil structure can provide a good misalignment tolerance. A maximum variation of the power transfer efficiency (PTE) is only 18.0% under angular misalignment of 90° and 23.4% under lateral misalignment of 37.5% of the transmitting coil’s diameter, which indicates the proposed coil structure can meet the demand of IPT systems in retinal prosthesis applications.