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Magnetics, IEEE Transactions on

Issue 1  Part 1 • Date Jan. 2013

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  • Front cover

    Publication Year: 2013 , Page(s): C1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2013 , Page(s): C2
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  • Table of Contents

    Publication Year: 2013 , Page(s): 1 - 3
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  • Chairman's Foreword

    Publication Year: 2013 , Page(s): 4
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  • Preface [Selected Papers from the 9th European Magnetic Sensors and Actuators Conference (EMSA 2012)]

    Publication Year: 2013 , Page(s): 5 - 6
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  • Magnetic Nanoparticles for Therapy and Diagnostics

    Publication Year: 2013 , Page(s): 7 - 10
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1376 KB) |  | HTML iconHTML  

    The research and utilization of the magnetic nanoparticles in, e.g., biology and medicine have been preferentially oriented on magnetite Fe3O4 and maghemite γ-Fe2O3. The complex oxides allow a better control of the magnetic properties in a desirable way. We demonstrate this approach on an example of the La1-xSrxMnO3 perovskites from the point of view of their use in self-controlled magnetic fluid hyperthermia and increase of contrast in magnetic resonance imaging. With materials possessing suitable values of transition temperature TC, coercivity and magnetization, the heating power generated by the nanoparticles was estimated by two independent methods and they were finally employed in vitro and in vivo hyperthermia experiments. View full abstract»

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  • Properties of Fe-Al Cores Made From Fe-Al Powders Annealed in a Damp Hydrogen Atmosphere

    Publication Year: 2013 , Page(s): 11 - 14
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1921 KB) |  | HTML iconHTML  

    Gas-atomized Fe-4, 6wt.%Al powders were annealed in a damp hydrogen atmosphere with a dew point of 0°C and -17°C in order to cover the powder surface with a high electrical resistivity layer of Al2O3 and then compressed into cores. The powders should be oxidized at a temperature higher than 800 °C in order to oxidize the aluminum alone on the surface of powder, as confirmed by simulation using the STANJAN program. An Al-rich layer, i.e., an Al2O3 layer, was formed on the surface of the Fe-Al powder, as confirmed by SEM. Loss of the cores made from the selectively oxidized powders was much lower than those of the cores with phosphate coats, so the selectively oxidized powder can be used to fabricate electrical actuators with high levels of performance. View full abstract»

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  • Anisotropy Field in Ni Nanostripe Arrays

    Publication Year: 2013 , Page(s): 15 - 17
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (482 KB) |  | HTML iconHTML  

    Anisotropy fields of nanostripe arrays can be investigated by various techniques. One of these techniques is the ferromagnetic resonance spectroscopy due to the fact that the resonance field depends directly on the anisotropy field strength and its angular spread. In order to understand the dynamic fenomena in these samples, nanostripe arrays of Ni have been prepared by interference lithography. The film thickness is 45 nm for a lattice period of 2.7 μm and the stripe width equals 1500 and 750 nm. Ferromagnetic resonance measurements have been carried out at a frequency of 9.75 GHz as a funcion of H. The resonance field of the absorption peak increases upon changing the angle from parallel (0°) to perpendicular (90° ) to the film plane. This behaviour can be explained by the relation between resonance field, frequency and anisotropy field determined by demagnetizing factors and magnetization angle with respect to the sample easy axis direction after energy minimization. View full abstract»

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  • GMI in Nanostructured FeNi/Ti Multilayers With Different Thicknesses of the Magnetic Layers

    Publication Year: 2013 , Page(s): 18 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1671 KB) |  | HTML iconHTML  

    Nanostructured multilayers are proposed as a competitive alternative to magnetoimpedance (MI) thick films. However, the effect of the thickness of the magnetic layers on the properties of MI multilayers is still unclear. To perform a systematic study, three multilayered structures consisting of magnetic Fe20Ni80 layers and nonmagnetic Ti layers were prepared by sputtering. In each structure, FeNi layers have different thickness (25, 50, and 100 nm) keeping the same total thickness. Magnetic measurements and magnetic domain structure observations were used for the characterization of the samples. The MI of FeNi/Ti- based multilayers was evaluated in terms of the magnitude of the impedance variations and its sensitivity with respect to the applied magnetic field. The results show that the multilayer with 50 nm FeNi layers has a slightly better properties than the sample with a 100 nm FeNi layers, while the sample with a 25 nm thick FeNi layers performs considerably worse. The sample [FeNi(50 nm)/Ti(6 nm)]7FeNi(50 nm) displays a MI ratio of 24% at 200 MHz and a sensitivity of 135% kAm-1 at 140 MHz. View full abstract»

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  • Alternative Route for Obtaining {\rm NiFe}_{2}{\rm O}_{4} Thin Films by Pulsed Laser Deposition

    Publication Year: 2013 , Page(s): 22 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1438 KB) |  | HTML iconHTML  

    Ferrites in thin film form are usually obtained by pulsed laser deposition (PLD). This method can induce the presence of secondary phases, a problem which requires an annealing process. The study aimed at finding a PLD based method through which, in further studies, ferrites with a controllable phase composition can be obtained. Therefore, we obtained ferrite thin films in oxygen atmosphere and in high vacuum. Raman spectroscopy measurements for the samples obtained in high vacuum revealed the formation of magnetite. Instead of annealing, we irradiated these samples with an excimer laser (λ = 308 nm), at various frequencies, for certain amount of pulses. The Raman spectra revealed the formation of the nickel ferrite phase, as well as the presence of residual magnetite phase. View full abstract»

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  • Synthesis and Characterization of Co-Substituted Ferrite Nanocomposites

    Publication Year: 2013 , Page(s): 26 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (581 KB) |  | HTML iconHTML  

    We report the synthesis of CoxNi1-xFe2O4 (where x is 0, 0.25, 0.50, 0.75, 1) nanoparticles (NPs) by a wet chemical method using carboxymethyl cellulose (CMC) solution as surfactant. Their structure and magnetic properties were evaluated by X-ray diffraction (XRD), Fourier-Transform Infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The gas and humidity sensing properties of the samples were also investigated. Powder X-ray diffraction analysis demonstrated the formation of face-centered cubic structure for all the samples. The average crystallite size and lattice parameters have been calculated by Rietveld refinement. The FTIR spectra of NPs confirm the presence of CMC functional groups and stretching bands attributed to the intrinsic vibrations of tetrahedral and octahedral sites of spinel ferrite. The magnetization curves of the nanocomposites at room temperature demonstrated saturation magnetizations from 21 emu/g to 58 emu/g and coercivity values between 130 Oe and 835 Oe. As not many studies have been published on this topic, the gas sensing properties of Ni-substituted Co ferrites have been evaluated. The measurements revealed that Co0.25Ni0.75Fe2O4 is the most sensitive to acetone vapors. View full abstract»

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  • Tailoring the Switching Field Dependence on External Parameters in Magnetic Microwires

    Publication Year: 2013 , Page(s): 30 - 33
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (322 KB) |  | HTML iconHTML  

    We have studied the effect of thermal treatment on the sensitivity and stability of the switching field in bistable glass-coated Fe-Ni-Si-B microwire. We have found that annealing at 300°C/1 hour leads to the increase in the sensitivity of the switching field to the applied external stress. Moreover, the switching field fluctuation decreases after such treatment as a result of domain structure stabilization through the structural relaxation. View full abstract»

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  • Effects of Annealing Treatment on Low and High Frequency Magnetic Properties of Soft/Hard Biphase FeSiB/CoNi Microwires

    Publication Year: 2013 , Page(s): 34 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (897 KB) |  | HTML iconHTML  

    Soft amorphous Fe76Si13B11 microwires were fabricated by Taylor-Ulitovsky technique and an external Co90Ni10 shell with magnetically harder behavior was additionally grown by combined sputtering and electro-plating techniques. The effect of annealing treatment at temperatures up to 700°C for 1 h on low-frequency coercivity and the ferromagnetic resonance, FMR, frequency for single and biphase microwires was investigated. The properties after low temperature annealing (up to 500 °C) are reasonably maintained, which indicates the suitability of these families of wires for sensing applications up to relatively high temperatures. Nevertheless, low and high frequency properties are significantly deteriorated after crystallization of the amorphous core. FMR behavior was analyzed by fitting to Kittel equation for annealed samples. The observed different absorption peaks are correlated with the presence of the soft core and the external shell. View full abstract»

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  • Magnetopolymer Composites With Soft Magnetic Ferrite Filler

    Publication Year: 2013 , Page(s): 38 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (666 KB) |  | HTML iconHTML  

    Thanks to their good magnetic properties, NiZn ferrites can be used as the soft magnetic filler in magneto-polymer composites. The ferrites having general composition NixZn1-xFe2O4 ( x=0.30, 0.33, 0.36, 0.42, and 0.50) were prepared by means of ceramic method and the magnetic properties, such as initial permeability μi and Curie temperature TC were investigated. The sample with composition Ni0.33Zn0.67Fe2O4 having μi=1316 and TC=95°C was chosen as the filler for magneto-polymer composites. The aim of the work was the study of preparation and properties of magnetic polymer composites based on natural rubber SMR 20 in a wide range of concentrations (0-600 phr). The influence of ferrite content on magnetic, physical-mechanical and rheological properties of prepared composites was investigated. The effect of the concentration of ferrite filler on the complex permeability μ = μ'-jμ'' of the composites in the frequency range from 10 MHz to 3 GHz as well as the physical-mechanical and rheological properties is evident. View full abstract»

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  • Improving the Magnetoelectric Response of Laminates Containing High Temperature Piezopolymers

    Publication Year: 2013 , Page(s): 42 - 45
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (371 KB) |  | HTML iconHTML  

    High magnetoelectric (ME) coefficients at room temperature have been found when 2-2 type laminates (one magnetostrictive, the other piezoelectric) made of iron-based Metglas alloys and PVDF piezoelectric polymer are used. Searching for a good ME response of such laminate composites when used at high temperatures, we have modified both constituents: first, by using magnetostrictive Metglas 2826 MB (with λs ≈ 11 ppm) in the ribbon form thermally treated at high temperature, in order to get internal stress-relief conditions. The main consequence of such thermal treatment has been to achieve a piezomagnetic coefficient of d33=1.5×10-6/Oe, higher than the measured one in the as-cast state for this alloy. As piezoelectric constituent, we have used a new class of high temperature piezopolymer: a series of nitrile containing polyimide copolymers were fabricated with a mixture of two aromatic diamines, namely 1,3-Bis-2-cyano-3-(3-aminophenoxy)phenoxybenzene (diamine 2CN) and 1,3-Bis(3-aminophenoxy)benzene (diamine 0CN). Those diamines were in 30/70, 40/60, and 50/50 proportions within the 0CN/2CN mixture. We have measured room temperature ME coefficients up to 0.37 V/cm.Oe, being this value directly correlated to the remnant polarization of each copolyimide. View full abstract»

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  • Magnetic Measurements of RE-Doped Cobalt Ferrite Thin Films

    Publication Year: 2013 , Page(s): 46 - 49
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    Cobalt ferrite is a ferrimagnetic material with properties which support its use in different types of devices. In bulk form CoFe2O4 presents the highest magnetostriction coefficient relative to other ferrites making it a good candidate for sensors and actuators. Due to the industries miniaturization trend, several research groups focused their study on obtaining novel thin films with high magnetostriction coefficient. The aim of this work was to investigate the influence of the substrate temperature and rare earth addition on the properties of cobalt ferrite thin films deposited by pulsed laser deposition. CoFe2O4, CoFe1.8Gd0.2O4 and CoFe1.8La0.2O4 thin films were deposited using an Nd-YAG laser (532 nm) with a 10 Hz repetition rate and 10 ns pulse duration. The target-substrate distance of 2.5 cm and laser fluence of 10 J/cm2 were kept constant. The substrate temperature was varied from 200 °C to 600 °C. The structural properties of the thin films obtained by Raman spectroscopy and scanning electron microscopy indicated the formation of a single cobalt ferrite structure. Hysteresis loops for both in-plane and out-of-plane configuration were obtained using a vibrating sample magnetometer. These results showed an increase in coercive field and maximum magnetization as the substrate temperature was raised from 200 °C to 400 °C. Vibrating sample magnetometer measurements of the cobalt ferrite thin film deposited at 400 °C revealed a tendency of the particles to a perpendicular magnetic arrangement. View full abstract»

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  • Prospects of Using In-Containing Semiconductor Materials in Magnetic Field Sensors for Thermonuclear Reactor Magnetic Diagnostics

    Publication Year: 2013 , Page(s): 50 - 53
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (838 KB) |  | HTML iconHTML  

    The work presents the results of experimental investigation into the effect of neutron irradiation on thin-film magnetic field Hall sensors. It is shown that sensors based on InSb/i-GaAs heterostructures are promising for application under radiation conditions in thermonuclear reactor magnetic diagnostics systems. At the same time, the presence of buffer layers in InAs/i-GaAs heterostructures makes this material unfit for application under neutron flux conditions. View full abstract»

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  • The Magnetocaloric Effect of Heusler Microwires in Low and High Magnetic Fields

    Publication Year: 2013 , Page(s): 54 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (565 KB) |  | HTML iconHTML  

    We are dealing with the influence of Hopkinson effect on magnetocaloric effect in glass-coated Ni-Mn-In-Co microwires in the given contribution. We have shown that although the entropy change is smaller in low fields, the refrigerant capacity per unit of applied field is three times higher for low field (300 Oe) comparing to that of 30 kOe. This points to the fact that Hopkinson effect can be employed to increase the efficiency of magnetocaloric effect. View full abstract»

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  • Towards Wafer Scale Inductive Determination of Magnetostatic and Dynamic Parameters of Magnetic Thin Films and Multilayers

    Publication Year: 2013 , Page(s): 58 - 61
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (601 KB) |  | HTML iconHTML  

    We investigate an inductive probe head suitable for noninvasive characterization of the magnetostatic and dynamic parameters of magnetic thin films and multilayers on the wafer scale. The probe is based on a planar waveguide with rearward high frequency connectors that can be brought in close contact to the wafer surface. Inductive characterization of the magnetic material is carried out by vector network analyzer ferromagnetic resonance. Analysis of the field dispersion of the resonance allows the determination of key material parameters such as the saturation magnetization MS or the effective damping parameter aeff. Three waveguide designs are tested. The broadband frequency response is characterized and the suitability for inductive determination of MS and aeff is compared. Integration of such probes in a wafer prober could in the future allow wafer scale in-line testing of magnetostatic and dynamic key material parameters of magnetic thin films and multilayers. View full abstract»

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  • Orthogonal Fluxgate With Annealed Wire Core

    Publication Year: 2013 , Page(s): 62 - 65
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (686 KB) |  | HTML iconHTML  

    Orthogonal fluxgate in fundamental mode has become a competitive sensor for low noise measurement of low frequency magnetic fields. The noise of this sensor has been recently reduced to 2.8 pT/√Hz at 1 Hz; however, it appears that noise lower than 2.5 pT/√Hz at 1 Hz cannot be achieved because of the physical limitations due to the intrinsic noise generated in the core of the fluxgate. In order to decrease the noise below 2.5 pT/√Hz at 1 Hz, Barkhausen noise generated in the core must be reduced. For this purpose, we annealed the amorphous wire used as the core of the sensor in an infrared furnace while a dc current was flowing through the wire. The dc current generated a circumferential field large enough to saturate the wire in a circumferential direction, and by annealing the saturated wire, we increased the circumferential anisotropy. We illustrate the dependence of circumferential anisotropy on dc current in the wire as well as on temperature and time of annealing. We then demonstrate that larger circumferential anisotropy helps reduce the noise of the sensor suppressing the Barkhausen noise when the fluxgate is operated in fundamental mode. As a result, a 1.8 pT/√Hz noise at 1 Hz was achieved with annealed wire, which is far below the 2.5 pT/√Hz minimum noise achievable for sensors with as-cast wires. View full abstract»

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  • Calibration of the 3-D Coil System's Orthogonality

    Publication Year: 2013 , Page(s): 66 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    Two methods were tested for calibration procedures of the 3-D coil system which is used as a source part of the magnetic tracker. Precise magnetometer's positions with respect to the coil system were used for determining of the nonorthogonality of the coil system as well as for determining of the magnetic moment. The needed number of the reference positions was measured to calculate six unknown calibrated parameters. In comparison, the 3-D coils system was also calibrated with a method which employs the orthogonal homogenous ac field generated in Helmholtz coils. The misalignment of up to two degrees was discovered. View full abstract»

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  • Metal Detector Signal Imprints of Detected Objects

    Publication Year: 2013 , Page(s): 69 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (863 KB) |  | HTML iconHTML  

    Humanitarian demining missions are activities in which an operator safety and time consumption are key issues. To increase a discrimination ability of ATMID metal detector, which we have been using, we extended the capability of the detector with mounting inertial measurement unit (IMU) supplemented by two optical distance sensors on the detector head. That enabled us to perform dead reckoning based on accelerations and angular rates measured by IMU in all three axes. Optical distance sensors have been used for compensation purposes and an initial distance measurement. Our main aim was to interconnect magnetic imprint sensed by the detector with precise localization of its head, which led to imprint size estimation as well as its position. Due to low-cost micro-electro-mechanical system (MEMS) based IMU implementation we have had to deal with unstable dead reckoning outcomes. For this reason we used our designed complex magnetic markers (CMMs) which demarked a searched area plus provided us with precise positioning at its both edges. The main contribution of this paper is in the study and identification of CMM magnetic imprints characteristics and their differences related to various aspects of CMM usage during demining procedure and its conditions. The characteristics of CMMs have been studied and analyzed according to several laboratory experiments and results are presented. View full abstract»

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  • Measurement of DC Currents in the Power Grid by Current Transformer

    Publication Year: 2013 , Page(s): 73 - 76
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    DC currents in power grids are mainly caused by geomagnetic activity especially during magnetic storms. It is desirable to monitor these currents to prevent saturation of transformers, which may cause blackout. However, adding DC current sensors to existing installations would be very costly. We suggest to convert some of the existing current transformers to fluxgate DC current sensors by injecting AC excitation current into their secondary winding. We successfully tested this concept on 500 A current transformer. The achievable accuracy is 10% for DC currents and 1.5% for AC currents, which is sufficient for protection and monitoring purposes. We analyze the DC current sensitivity dependence on the (changing) grid impedance, and we show that the sensitivity can be stabilized by controlling the secondary voltage component at the excitation frequency. Excitation current injected into the grid also depends on the grid impedance, but for realistic conditions it is below 2 A. View full abstract»

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  • Impulse Current Transformer With a Nanocrystalline Core

    Publication Year: 2013 , Page(s): 77 - 80
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (626 KB) |  | HTML iconHTML  

    The objective of this paper is to propose and to validate the behavior of an impulse current transformer with a nanocrystalline alloy toroidal core. The purpose of this transformer is to measure a current square waveform with a fundamental harmonic frequency of 25 kHz. Current ratio 1:1 and the real burden are assumed, and the transformer will operate in an electric power system at voltage levels up to 25 kV. These special requirements are typical for applications such as photovoltaic power plants, where the currents in high voltage inverters need to be measured. These inverters usually use the principle of pulse width modulation (PWM), and are able to convert from a low voltage direct current to high voltage alternating current. In this way, the electric power can be supplied directly to the high voltage distribution grid without the use of a power transformer. View full abstract»

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  • Neel Effect Toroidal Current Sensor

    Publication Year: 2013 , Page(s): 81 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB) |  | HTML iconHTML  

    In this paper, a configuration for a Neel effect ac-dc current sensor designed with second harmonic sensing in view is proposed. This configuration relies on the use of two toroidal superparamagnetic cores wound in opposite direction with respect to each other and connected in series. An analytical model is developed, which shows that the component of the output signal at the excitation frequency, which is useless, should be removed provided that the windings are symmetrical. The latter principle is validated experimentally and a prototype device is characterized for different excitation conditions. Open loop dc and ac current measurements are carried out over the [-110 A, 110 A] range. View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Meet Our Editors

Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology