Layer Of Magnetic Material Research Articles

MODELING AND OPTIMIZATION OF AN INTEGRATED PLANAR INDUCTOR WITH TWO LAYERS OF MAGNETIC MATERIAL

The objective of the work carried out in this document is to develop an electrical model of an inductor with two layers of magnetic material. Simulation and optimization have allowed us to develop a model and in order to validate it, we have realized in the laboratory integrated planar components with two layers of magnetic materials.The different technological steps from copper deposition to the realization of the top layer (in the case of two-layer inductors), through exposure, etching, gilding, lapping, sawing, polishing and bonding have been described (Table 1). These steps required the use of the technological means of the laboratory.From the elements extracted by the optimization program, the admittance parameters Y11 and Y12 were recalculated and compared with those obtained by simulation. We noted a good agreement between the measurement and the simulation.

Influence of interface layer insertion on the spin Seebeck effect and the spin Hall magnetoresistance of Y3Fe5O12 /Pt bilayer systems

We observe significantly enhanced spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) values by inserting 0.3--0.6-nm-thick layers of magnetic materials with different composition (Cr, ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$, ${\mathrm{Co}}_{90}{\mathrm{Fe}}_{10}$, ${\mathrm{Fe}}_{50}{\mathrm{Co}}_{50}$, and Fe) at the ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$/Pt interface. To study the actual magnetic state of these insertion layers, we, then, investigated the magnetization of these layers via generalized magneto-optical ellipsometry. Magnetic insertion layers in this thickness range did not exhibit a measurable magnetization, even though our method should have detected even a small fraction of the bulk magnetization value for the utilized materials easily. Therefore, the observed SSE and SMR enhancement generated by the insertion of thin magnetic material layers did not result from a net interface magnetization but might, instead, be related to the paramagnetic state of the inserted layers.

Magnetic Susceptibility of Ferromagnetic Alloy Material Co (1-x) Ni (x) Nanocube and Nanosphere Models

A hard disk is a data storage medium composed of a thin layer of magnetic material. Hard drives take advantage of the characteristics of magnetic materials that are stable to heat and have sensitivity to magnetic fields. One of the best materials to use a thin layer ferromagnetic on a hard disk is CoNi alloy. Hard drives with larger storage capacities require magnetic materials with high magnetic susceptibility values and Curie temperatures to obtain the best magnetic properties. The magnetic susceptibility of alloy ferromagnetic material Co (1- x) Ni (x) nanocube and nanosphere is calculated using vampire-based micro magnetic simulation. The research was conducted using a literature review on the parameters of the CoNi alloy material, and then it was simulated in the vampire program. The data generated from the simulation are magnetic susceptibility (1/tesla) and temperature (K). The spectrum of the magnetic susceptibility graph that shifts to the right as the Ni (x) composition decreases, it is assumed that the higher Curie temperature is produced. Otherwise, The increase in Ni (x) composition causes the magnetic susceptibility spectrum to shift to the left, with the Curie temperature's predicted value getting minor than the other. The nanocube-shaped material has a higher susceptibility value than the nanosphere-shaped material in terms of each Ni (x) composition variation at its maximum magnetic susceptibility.

Conception and Manufacturing of a Planar Inductance on NiFe Substrate

The present paper presents the study, realization and characterization of a micro-coil sandwiched using a relatively thick layer of magnetic material. The integration of this micro-coil with as a starting point a set of specifications, requires the following steps: Identification and validation of geometric parameters for the calculation of electrical parameters. Losses dissipated as heat in these electronic systems are becoming a major concern for designers. This prompted to take into account the thermal design. The results obtained have allowed to realize a micro-coil micro square planar coil sandwiched shaped between two magnetic materials. Several carried measures focused on the inductance and resistance which are related to the frequency f, the module and phase of the impedance, and the gap g. The operation of these data is used to trace the evolution of the inductance value Ls, the quality factor Q and the resistor Rs as a function of frequency.

Increase in Robustness against Effects of Coil Misalignment on Electrical Parameters Using Magnetic Material Layer in Planar Coils of Wireless Power Transfer Transformer

Utilization of wireless power transfer in light rail transits is seen as one solution for electrification of lines. The main advantage of this supply system is the reduction of installation; moreover, the alignment between the transmitter coil in the track and the receiver coil in the train should be perfect in order not to affect the power transfer. To reduce the effects of misalignment on the input and output electric parameters of the system, a new planar core and coil design, called hybrid intercore coil, is proposed. The proposed design uses a magnetic material layer between the windings in the inner half of the coil to create a non-uniform magnetic field distribution, which makes the system more robust against the effects of coil misalignment on the system current and voltage. Simulations with finite element method software were conducted to compare designs. The results show that the proposed design is less susceptible to the effects of misalignment and is more efficient. Prototype cores were constructed to verify the simulation results. Measurements show a smaller input overcurrent and output overvoltage when operating in resonance mode. The proposed design reduced the effects of coil misalignment on electrical parameters.

Design of an ultra-thin absorption layer with magnetic materials based on genetic algorithm at the S band

In this work, we design an ultra-thin absorption coating at the S band, and the total thickness is less than 2 mm. For incident angle less than 30 degree and the whole S band, the reflection is less than −5 dB. The coating is constructed with 4/3 layers of magnetic material with different thicknesses, which are optimized by using genetic algorithm. Analytic and simulation results confirm the correctness of the design.

Characteristics of a Tunable Microstrip Bandpass Filter Under the Influence of Magnetic Field

A magnetic-field tunable 2.4 ㎓ microwave bandpass filter having insertion loss ＜ −5㏈ on an FR4 substrate with the flaky magnetic material was designed and characterized. The tunability in the designed bandpass filter was achieved by adhering soft magnetic materials on top of the device. This soft magnetic material can be composed of ferromagnetic substance or ferrimagnetic substance. The performance of the designed bandpass filter under its influence is investigated. The frequency offset ratio changes over 30 %. There is over 20 % change in the center frequency towards the lower frequency region due to this application. These magnetic material layers achieved the center frequency shift and bandwidth extension without actually changing the original structure of the device.

Initiator-Integrated 3-D Printing of Magnetic Object for Remote Controlling Application

Magnetically driven micromachines play an essential role in a number of biomedical and other remote control applications. In this paper, a magnetically driven robot composed of customized UV-curable resin was fabricated by (3-D) printing via initiator-triggered radical polymerization and the subsequent polyelectrolyte-brush-assisted electroless plating. A layer of magnetic material was grown in situ on the 3-D printed structure, which exhibited soft-magnetic properties proved by the vibrating sample magnetometer measurement. The magnetic robot was successfully actuated under the rotating magnetic field produced from a manipulator of permanent magnet. By utilizing the spiral structure, the 3-D robot was designed to translate rotational movement into linear motion. A comprehensive investigation was also carried out on the optimization of spiral shape, liquid viscosity and the strategy of magnetic controlling. The remote controlling experiments demonstrate that this initiator-integrated 3-D printing is an effective technique for making magnetically driven objects.

Mitigation of Magnus Force in Current-Induced Skyrmion Dynamics

Current-driven skyrmions drift from the intended direction of motion in a thin magnetic film due to the presence of the Magnus force and are annihilated upon reaching the film edge. This paper proposes two methods to engineer a 1-D potential well to confine the skyrmion motion in the center region of nanowires, thus preventing annihilation. By patterning the magnetic anisotropy of the film or by adding a layer of magnetic material at the edges, the barrier height and width of the potential well can be controlled. Magnetic skyrmions in such nanowires can then be guided to traverse only along the axis of the nanowire, even in the nanowires with steep bends. In addition, we also report a compression mechanism in which the skyrmion size and separation distance can be reduced by modifying the potential well, thus increasing the skyrmion packing density in a nanowire. The guided motion and high skyrmion density made possible by our proposed methods will allow the realization of high-density skyrmion-based memory.

Magnet-controlled surface defect modes of photonic crystal

In order to obtain tunable surface modes of photonic crystal, we add a magnetic material layer on the truncated surface of a two-dimensional photonic crystal. Through calculations of photonic band, we obtain the surface defect modes in the first and second gaps. Through the modulation of applied magnetic field, we can control the frequency, the group velocity and the exciting incidence direction of the surface defect mode. In particular, in the frequency range of surface defect modes, we can tune the group velocity to zero.

Magnetic interactions in CoCrPt-oxide based perpendicular magnetic recording media

First order reversal curves (FORC) method has been reported to be an efficient tool to study interaction between grains and layers of magnetic materials. Although a few studies have been carried out on perpendicular recording media in the past, a study on the effect of systematic variation of exchange interaction in granular perpendicular magnetic recording media on FORC contours has not been carried out in detail. Such a study will help to understand the use of FORC better. In this paper, we have made a systematic set of samples in order to study the variation in exchange coupling and its effect on FORC contours. The pressure during the deposition of the second ruthenium layer and the magnetic layer was varied to alter the separation between the grains and hence the exchange interaction between the grains in the CoCrPt-oxide recording layer. In addition, the thickness of Co-alloy cap layer was used as an additional tool to control the exchange interaction between the magnetic grains. The results indicated that the interaction field obtained from the FORC does not vary in a significant manner when the changes in exchange interaction are small. In comparison, the peak intensity of the FORC shows a clear trend as the exchange coupling is varied, making it a more suitable parameter to study the exchange and magnetostatic interactions in systems such as magnetic recording media.

Design and preparation of a low frequency absorber based on hollowed-out cross-shaped meta-material structure

A hollowed-out cross-shaped meta-material structure is designed and fabricated in this work. A kind of conventional magnetic material which works at low frequency is used as the absorber substrate. The simulation results demonstrate that an absorber can reach an absorption of less than -10 dB in a range between 2 GHz and 4 GHz, and the absorption band is expanded by a 0.5 GHz when the meta-material structure is unloaded. The experimental results indicate that a similar absorption band appears between 2.5 GHz and 5.1 GHz, which is 0.48 GHz wider than meta-material structure and the absorption band is expanded by 23% when the depth of absorption band below -9 dB. Compared with the cross meta-material, the hollowed-out structure has ability to increase the magnetic energy loss and strengthen the coupling between the units. The influence of magnetic layer thickness on absorption capability of wave absorber is analyzed. The result indicates that the position of addition absorption band does not apparently move with variation in thickness of the magnetic material layer. Based on these results, two different meta-material structures are combined to obtain a wider absorber. The simulation result and the experimental result both show another 0.9 GHz expansion of the absorption band and it can also reduce the thickness of the magnetic layer.

RETRACTED: Ultrahigh magnetoresistance at room temperature in molecular wires.

Systems featuring large magnetoresistance (MR) at room temperature and in small magnetic fields are attractive owing to their potential for applications in magnetic field sensing and data storage. Usually, the magnetic properties of materials are exploited to achieve large MR effects. Here, we report on an exceptionally large (>2000%), room-temperature, small-field (a few millitesla) MR effect in one-dimensional, nonmagnetic systems formed by molecular wires embedded in a zeolite host crystal. This ultrahigh MR effect is ascribed to spin blockade in one-dimensional electron transport. Its generic nature offers very good perspectives to exploit the effect in a wide range of low-dimensional systems.

A carpet cloak for static magnetic field

We present a two-dimensional carpet cloak for static magnetic field, a design that renders the magnetic response of a given volume invisible from its exterior, without altering the external magnetic fields. The device is designed using transformation optics method and can be implemented with alternating superconducting and magnetic material layers. Through the proper design of the constitutive tensors and relative thicknesses of each slab, we achieve the perfect performance of invisibility. Full wave numerical simulations confirm our design.

Magnetic superlens-enhanced inductive coupling for wireless power transfer

We investigate numerically the use of a negative-permeability “perfect lens” for enhancing wireless power transfer between two current carrying coils. The negative permeability slab serves to focus the flux generated in the source coil to the receiver coil, thereby increasing the mutual inductive coupling between the coils. The numerical model is compared with an analytical theory that treats the coils as point dipoles separated by an infinite planar layer of magnetic material [Urzhumov et al., Phys. Rev. B 19, 8312 (2011)]. In the limit of vanishingly small radius of the coils, and large width of the metamaterial slab, the numerical simulations are in excellent agreement with the analytical model. Both the idealized analytical and realistic numerical models predict similar trends with respect to metamaterial loss and anisotropy. Applying the numerical models, we further analyze the impact of finite coil size and finite width of the slab. We find that, even for these less idealized geometries, the presence of the magnetic slab greatly enhances the coupling between the two coils, including cases where significant loss is present in the slab. We therefore conclude that the integration of a metamaterial slab into a wireless power transfer system holds promise for increasing the overall system performance.

Frequency characterization of thin soft magnetic material layers used in spiral inductors

The paper details the characterization of thin magnetic materials layers, particularly soft materials, with respect to their behaviour in frequency (from 10MHz to 1GHz). The proposed method is suitable for any soft but insulating magnetic material; Yttrium Iron Garnet (YIG) is used as an example. The principle is based on a comparison between simulations for different values of the permeability and measurement values versus frequency of planar inductor structures; an experimental validation is proposed as well. Thin magnetic material is first deposited on an alumina substrate using RF sputtering technique; a planar spiral winding of copper is then deposited on the magnetic material by the same technique. The effective permeability versus frequency is obtained by comparing two samples of spiral windings with and without magnetic material. Network analyser measurements on samples of various geometrical dimensions and of different thicknesses are necessary to determine the effective magnetic permeability; we have obtained a relative effective permeability of about 30 for seven turns spiral inductor of a 17μm YIG film.

Experimental verification of metamaterial based subwavelength microwave absorbers

We designed, implemented, and experimentally characterized electrically thin microwave absorbers by using the metamaterial concept. The absorbers consist of (i) a metal back plate and an artificial magnetic material layer; (ii) metamaterial back plate and a resistive sheet layer. We investigated absorber performance in terms of absorbance, fractional bandwidth, and electrical thickness, all of which depend on the dimensions of the metamaterial unit cell and the distance between the back plate and metamaterial layer. As a proof of concept, we demonstrated a λ/4.7 thick absorber of type I, with a 99.8% absorption peak along with a 8% fractional bandwidth. We have shown that as the electrical size of the metamaterial unit cell decreases, the absorber electrical thickness can further be reduced. We investigated this concept by using two different magnetic metamaterial inclusions: the split-ring resonator (SRR) and multiple SSR (MSRR). We have also demonstrated experimentally a λ/4.7 and a λ/4.2 thick absorbers of type II, based on SRR and MSRR magnetic metamaterial back plates, respectively. The absorption peak of the SRR layout is 97.4%, while for the MSRR one the absorption peak is 98.4%. The 10 dB bandwidths were 9.9% and 9.6% for the SRR and MSRR cases, respectively.

Enhancement of Magnetostriction in Internally-Biased Terfenol-D 2-2 Composites

A key issue in the fabrication of Terfenol-D 2-2 composites with internal magnetic field biasing is the selection of appropriate constituent materials to obtain high magnetostriction while keeping optimum magnetomechanical properties. The fabrication process is costly and time consuming and, therefore, numerical methods to predict their properties are useful. In this paper, finite element analysis (FEA) of the magnetostriction of such composites has been carried out using the commercial package ABAQUS. It has been shown that composites fabricated using Nd2Fe14B for the permanent magnetic material layers possess the highest internal fields within the Terfenol-D layers, although the overall strain of these composites is limited to approximately 800 times 10-6 due to the high elastic modulus of Nd2Fe14B. Simulations showed that the strain can be enhanced by choosing a different material with a lower elastic modulus for the permanent magnetic layer even though the internal field is lower. The simulations showed that the strain can increase by 12% if the Nd2Fe14B layer is substituted by SmCo5; by 23 % if it is substituted by Sm2Co17; and by 35 % if it is substituted by Alnico.

Numerical investigation of magnetic sensor for DNA hybridization detection using planar transformer

This paper introduces a sensor for detection of DNA hybridization and investigates its performance by means of computer simulation. A planar transformer with spiral windings is proposed for hybridization detection. In order to detect the occurrence of hybridization, single strand target DNA’s are tagged with magnetic beads. Target DNA’s are then exposed to known single strand probe DNA’s which are immobilized on the surface of a functionalized layer in the proximity of the sensor. The primary winding of the transformer is driven by an AC current source. The voltage at the secondary winding is used for detection. Once the hybridization is occurred, a layer of magnetic material is formed and the coupling between the windings is varied. These variations are reflected into the detecting output voltage. The magnitude of the output voltage is numerically calculated in terms of geometrical and physical parameters and the parameter values resulting in maximum response are derived.

Reflectionless absorption of electromagnetic radiation in a magnetic layer

The conditions for occurrence of total reflectionless absorption of electromagnetic waves in a layer of magnetic material applied to a metal substrate have been found. Their dependence on the layer thickness and the magnetic properties of the coating has been investigated. The frequency band within which this phenomenon can exist has been determined.