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Magnetics, IEEE Transactions on

Issue 5 • Date Sep 1992

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Displaying Results 1 - 25 of 407
  • Phases of NdFe10.7-xCoxTi1.3 alloys and magnetic properties of their nitrides

    Publication Year: 1992 , Page(s): 2566 - 2568
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    It has been found that the arc-melted NdFe10.7-xCoxTi1.3 (x=0/2/4/6) alloys have nearly single phase of ThMn12-type structure except the small amount of (Fe, Co)2Ti (or Fe2Ti) and α-Fe phases. The ThMn12-type phase forms as square prisms and (Fe, Co)2Ti (or Fe2Ti) exists between the grain boundaries as particles. Nitrification of this alloy system considerably increased the anisotropy field and Curie temperature. The dependence on cobalt content of the magnetic properties before and after the nitrification treatments shows almost the same trend; the Co-substitution increases the Curie temperature but decreases the anisotropy field. In the nitride system studied, NdFe10.7Ti 1.3Ny has the highest anisotropy field of about 6370 kA/m (80 kOe) View full abstract»

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  • Magnetic and structural properties of Fe3GeNx

    Publication Year: 1992 , Page(s): 2569 - 2571
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    Magnetic and structural properties of Fe3GeNx have been investigated. The FCC (face centered cubic) phase of FeGe absorbs nitrogen to x=0.24. As a result of absorption, the Curie temperature and room temperature magnetization decrease from 736 K and 137 emu/g to 614 K and 74 emu/g, respectively. The HCP (hexagonal close packed) phase of Fe3Ge, however, transforms to either FCC tetragonal phase, or a combination of these upon nitrogenation. The tetragonal nitride phase forms at a reaction temperature of 600°C to 650°C in a flowing atmosphere of ammonia. The phase is paramagnetic at room temperature and appears to order antiferromagnetically below 100 K View full abstract»

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  • Extraction magnetometry in an AC susceptometer

    Publication Year: 1992 , Page(s): 3066 - 3071
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A variable temperature, two-coil, two-position AC susceptometer has been used to perform absolute DC moment measurements using an extraction measurement technique. Virtually no hardware modifications were required and the full AC measurement capability is maintained. The signal analysis for the moment measurement is done using a high-speed digital voltmeter. The system can be configured to yield high-resolution DC moment measurements to 25 ppm and sensitivities to better than 5×10-5 emu. Typical DC measurement results are shown View full abstract»

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  • In-plane anisotropy studies in amorphous FeBSi films

    Publication Year: 1992 , Page(s): 2427 - 2429
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    Uniaxial anisotropy field Hk and local anisotropy fluctuation represented as magnetic ripple, S were studied as a function of argon pressure during deposition for the RF sputtered amorphous FeBSi films. The influence of PAr on Hk, Kloc , and S (structure constant) is discussed. The magnitude of S and Klocd3/2 were found to be strongly dependent on PAr View full abstract»

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  • Oriented barium hexaferrite thin films prepared by pulsed laser deposition

    Publication Year: 1992 , Page(s): 3216 - 3218
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Oriented thin films of barium hexaferrite, BaFe12O19, were grown in situ on (0001) sapphire substrates utilizing a pulsed laser deposition technique. X-ray diffraction, elastic backscattering spectrometry, ferrimagnetic resonance, and vibrating sample magnetometry confirm that the structure, composition, and magnetic parameters are consistent with films prepared by other techniques such as liquid phase epitaxy View full abstract»

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  • Mossbauer effect study of ordering in Fe-Al-Si and Fe-Al-Si-Ni magnetic thin films

    Publication Year: 1992 , Page(s): 2430 - 2432
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    Fe-Al-Si and Fe-Al-Si-Ni magnetic films with a thickness of 1 μm were deposited on crystallized-glass substrates by RF planar magnetron sputtering, and the changes in magnetic properties and microscopic structural changes in the films due to annealing were investigated. The films annealed at 500°C exhibited excellent soft magnetic properties for recording head materials. Fe-Al-Si-Ni films with high saturation magnetic-flux densities of 14.8 kG were obtained. Conversion electron Mossbauer spectroscopy showed that the disordered structure of α-type in as-sputtered films transformed into the ordered structure consisting of a mixture of B2- and DO3-types at a temperature of 500°C View full abstract»

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  • Self-biasing circulators operating at Ka-band utilizing M-type hexagonal ferrites

    Publication Year: 1992 , Page(s): 3219 - 3221
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The authors report on the fabrication and testing of millimeter-wave microstrip/stripline Y-junction circulator operating at Ka band. By exploiting the properties of high-anisotropy magnetic field, external magnetic field requirements are reduced. The design of microstrip/stripline circulators involves calculations of the radius of the ferrite disks and the port suspension angles in terms of the microstrip dielectric constant and saturation magnetization of the ferrite material. In addition, the operation frequency is determined largely by the uniaxial anisotropy field of the barium-strontium hexagonal ferrite View full abstract»

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  • Magnetic properties of rapidly quenched RFe7Six alloys

    Publication Year: 1992 , Page(s): 2841 - 2843
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    GdFe7Six and ErFe7Six (0⩽x⩽2.5) ribbons, whose X-ray diffraction lines correspond to that of hexagonal CaCu5-type structure, were prepared by a single roller quenching apparatus. Composition dependence of the Curie temperature and magnetization was found. The magnetization reorientation phenomenon in the ErFe7Si1.0 sample was also observed View full abstract»

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  • Magneto-optical recording in Co/Pt multilayer and GdTbFe-based disks at 820, 647 and 458-nm wavelength

    Publication Year: 1992 , Page(s): 2503 - 2505
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The magnetooptical recording performance of Co/Pt and GdTbFe-based disks was compared at three wavelengths. At 820 and 647 nm, the carrier-to-noise ratio of the GdTbFe disks was higher (2-3 dB) due to a lower noise level. At 458-nm wavelength, Co/Pt performed 3 dB better than the GdTbFe disk. The crystalline microstructure of Co/Pt did not cause a higher noise level than that of GdTbFe View full abstract»

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  • Viterbi detection of matched spectral null codes for PR4 systems

    Publication Year: 1992 , Page(s): 2889 - 2891
    Cited by:  Patents (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    Practical considerations for implementation of trellis coding in magnetic storage channels are examined in a simulation study. Matched spectral null codes are shown to offer significant coding gains on magnetic channels over baseline PRML (class-4 partial response maximum likelihood sequence estimation). In magnetic storage products, requirements of minimum detection latency and guaranteed worst-case performance dictate the use of non-quasi-catastrophic codes. Degradation in simulated error rate performance due to quantization effects prior to Viterbi detection is characterized. Detector performance in the presence of colored noise, introduced in equalization of a Lorentzian channel to class-IV response via a zero-forcing or least-mean-square equalizer, is shown. The results shown are consistent with an asymptotic coding gain on the order of 3 dB over baseline PRML, despite the presence of colored noise View full abstract»

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  • Magneto-inductive effect (MI effect) in amorphous wires

    Publication Year: 1992 , Page(s): 3150 - 3152
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Circumferential magnetic properties of amorphous magnetic wires (a-wires, for short) with three kinds of compositions (FeSiB, CoSiB, and FeCoSiB) and diameters of 120 μm and 50 μm are investigated applying an AC current using a BH hysteresis tracer. The magnitude of the induced voltage between both ends of the a-wire is decided by a differential permeability regarding circumferential flux change which is considered to occur principally in the outer shell of a-wires. A sensitive magneto-inductive (MI) effect is found in a-wires, in which the value of the inductance of a zero-magnetostrictive a-wire of 5 mm length changes up to about 75% for an external field of 0.8 kA/m (10 Oe). This MI effect is shown to be applicable to small magnetic heads and a cordless data tablet View full abstract»

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  • Measurement of transient temperature during thermomagnetic writing in MO recording media

    Publication Year: 1992 , Page(s): 2506 - 2508
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    Real-time Kerr contrast images produced by a time-resolved microscope were used to derive transient temperature during thermomagnetic (TM) writing. Temperature profiles in magnetooptical films during TM writing were measured, and Curie diameter could be derived. With 5-ns and 0.3-μm temporal and spatial resolutions, one could determine transient temperature during both heating and cooling cycles in TM writing with adequate resolutions. Since thermal parameters such as heat conductivity K, and specific heat C of thin films are difficult to measure accurately, the numerical analyses tend to fit C, K, and others to match reasonable transient temperature profiles. With the developed techniques, a more reliable way to determine the outcome of a TM writing is thus feasible. Moreover, these methods, in conjunction with numerical methods, can be used to derive more realistic values of the thermal parameters of material in thin-film form View full abstract»

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  • OPTIM, a primary expert system for magnetic field shaping

    Publication Year: 1992 , Page(s): 2056 - 2060
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    The basic principle, structure, and function of a primary expert system for magnetic field shaping are introduced. The intelligent inference network, inversion calculation method, optimal correcting process, and basic body of the knowledge base are expounded completely. An example of magnetic field shaping design calculation finished by this expert system is given View full abstract»

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  • Load/unload investigations on a rotary actuator disk drive

    Publication Year: 1992 , Page(s): 2877 - 2879
    Cited by:  Papers (7)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Head-disk contacts in a disk file with a rotary actuator are examined during load/unload using laser Doppler vibrometry and acoustic emission techniques. A novel scheme that allows tracking of the slider with the laser beam of a laser Doppler vibrometer during load/unload is implemented. Head-disk contacts are found to occur as a function of the velocity of the slider along the inclined ramp prior to loading, and it is shown that a low vertical loading velocity is less likely to introduce head-disk contacts than a high loading velocity. For the swing-arm actuated drive investigated, head-disk contacts start to appear at loading velocities as low as 25 mm/s. A careful design of the tip of the ramp is of utmost importance in ramp loading mechanisms to reduce the effective vertical component of the slider as it comes off the tip of the ramp during loading View full abstract»

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  • Micromagnetic Barkhausen emission analysis of Tb0.3Dy 0.7Fe2 under the action of an alternating field excitation

    Publication Year: 1992 , Page(s): 3153 - 3155
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The ternary alloy Tb0.3Dy6.7Fe2 has aroused great interest because of its minimum anisotropy among the alloys of dysprosium, terbium, and iron at room temperature, which allows high magnetostrictions to be obtained at low field strengths. In the present investigation, the Barkhausen effect emissions of this material have been analyzed with different techniques, including the waveforms, RMS voltages, and pulse height spectra of the Barkhausen signals View full abstract»

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  • Study of push-pull parametric transformer

    Publication Year: 1992 , Page(s): 2181 - 2183
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    The parametric transformer has voltage regulation, overload protection, and a kind of filter function for harmonic currents produced by nonlinear loads. The operating characteristics of the push-pull parametric transformer with resistive load are discussed. Furthermore, the authors demonstrate the operation of the push-pull parametric transformer with a thyristor rectifier circuit as an example of a nonlinear load. The authors propose an application of the transformer as a power supply for suppressing higher harmonic currents produced by nonlinear loads such as the thyristor rectifier circuit View full abstract»

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  • The inductance calculation of magnetic rods by using complementary finite element methods

    Publication Year: 1992 , Page(s): 2253 - 2255
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    The inductance of ellipsoidal magnetic rods for which the exact solution is known is calculated by using complementary finite-element methods. From this calculation, the range of the analyzed region and the number of nodes with which calculation errors are less than ±0.5% are presented. The inductance of cylindrical magnetic rods for which the exact solution is unknown is also calculated. It is shown that the measured values lie between the upper and lower bounds View full abstract»

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  • Rare-earth transition metal carbides

    Publication Year: 1992 , Page(s): 2572 - 2574
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Methane and ethane were used to prepare rare-earth transition metal carbides. The structural and magnetic properties of these carbides have been studied. Interstitial carbon atoms expand the unit cell of the R2Fe17 (R=Y, Ce, Pr, Nd, Sm, Dy, Er) and RFe10M2 (R=Y, Nd, Sm and M=Mo, V) structures by about 7.5 and 1.5%, respectively. Thus lattice expansion resulted in increases of Curie temperature and spontaneous magnetization. The easy magnetization direction of Sm2Fe17 is changed from planar to uniaxial with the carbon uptake, while in other R2Fe 17 compounds it remains planar. For RFe10 M2 with R=Y and Nd, a uniaxial anisotropy is observed after carbonation View full abstract»

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  • International Magnetics Conference (INTERMAG '92)

    Publication Year: 1992
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (48 KB)  

    The following topics were dealt with: magnetic recording heads; permanent magnet borides; transformers and inductors; magnetic sensors; superconductors; magnetic field calculations; permanent magnet nitrogenation; memory devices; particulate recording media; life science and magnetic separation; soft magnetic materials; magnetic measurements; giant magnetoresistance; optical storage; tribology; hysteresis; multilayers; magnetic recording system modelling; hard magnetic materials; recording system codes; domains and domain walls; magnetooptics; soft magnetic devices; permanent devices; magnetometers; thin film media; magnetic microscopy; magnetoelastic effects; magnetic fine particles; microwave magnetics; magnetic levitation and propulsion View full abstract»

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  • The analysis of the magnetostatic fields surrounding a twisted-pair transmission line using integral methods

    Publication Year: 1992 , Page(s): 2244 - 2246
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    An integral formulation is derived from the Biot-Savart law in conjunction with Gaussian numerical integral methods and applied to the computation of magnetic fields surrounding a two-wire twisted-pair transmission line in the static case. The results show the effects of the length of the pitch of the twisted-pair line on magnetic fields surrounding these lines and the 3-D nature of this field. It appears that, to obtain uniform heating, one should try different shapes for the exciting coils. Increasing the length of the heating coils improves the uniformity near the center of the workpiece, but has the effect of overheating at the edges. Changing the distance between the coils or the supply frequency does not have a significant effect on the heating pattern. The significance of the analysis lies in its relation to electromagnetic compatibility considerations which must be taken into account in the design of the electric power transmission and distribution system of NASA's Space Station Freedom (SSF) View full abstract»

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  • Magnetic field around an iron torus

    Publication Year: 1992 , Page(s): 2799 - 2801
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    The authors present a semianalytical solution of the magnetic field excited by an infinitely long current filament passing through the hole of an iron torus. This is the first 3-D analytical solution for a bounded multiply connected iron region. The solution can be of use when testing 3-D magnetostatic software. The solution is expanded by toroidal functions which are calculated by efficient algorithms. Computed results in the x-Y plane are given for an excitation of 1 A and torus relative permeability of 1000 View full abstract»

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  • Using SQUIDs for AC measurements

    Publication Year: 1992 , Page(s): 3072 - 3077
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    Experiments in which a general-purpose SQUID (superconducting quantum interference device) magnetometer has been equipped with an AC drive coil show that the system can operate from 0.001 Hz to 1.0 kHz with a sensitivity roughly independent of frequency above 0.1 Hz. This is consistent with the noise characteristics of the SQUID detection system. As in conventional AC measurement systems, determination of the relative phase between the applied AC field and the sample response is critical in determining the out-of-phase component of the signal. Initial experiments show that the system can provide significant improvement over conventional AC detection systems at low frequencies and small signal amplitudes. Extensions of this work may allow SQUIDs to function as high-sensitivity detectors at frequencies up to several megahertz for such applications as low-field nuclear magnetic resonance and nuclear quadrupole resonance View full abstract»

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  • 3D-CAD of an amorphous magnetostrictive sensor for monitoring the movements of the human spine

    Publication Year: 1992 , Page(s): 2397 - 2399
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    Parameters of a recently developed movement sensor using amorphous ferromagnetic alloys, such as distance of the coupling elements or geometry of the magnetization coil, were reflected in a numerical simulation using a three-dimensional finite-element program package. It was found that both linear behavior and high sensitivity cannot be achieved in the same sensor arrangement. Thus, each sensor must be designed according to its special application. Concentration of the magnetization coils at the sensor's ends should be considered only if high sensitivity is required and linear behavior is not essential. Furthermore, the proper functioning of the magnetostrictive bending sensor requires a homogeneous coil distribution over its length, thus requiring design compromises View full abstract»

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  • Microwave characteristics of YBCO coplanar waveguide resonator

    Publication Year: 1992 , Page(s): 2217 - 2219
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A theoretical formulation utilizing the incremental inductance method has been developed to calculate the coupling coefficient, London penetration depth, and surface resistance of a coplanar waveguide resonator fabricated from films of superconducting YBCO material. Experimental data of the reflection coefficient as a function of temperature and frequency agree reasonably well with calculations View full abstract»

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  • Finite element analysis of nonlinear magnetic devices combined with circuit equations by tableau approach

    Publication Year: 1992 , Page(s): 2256 - 2258
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    When simulating electric machines, the magnetic field analysis and the circuit calculation are closely coupled. The authors present a method in which the combination of Maxwell's equations and circuit equations is solved simultaneously. The tableau approach as nodal formulation is applied to the circuit model. The authors describe a novel generalized approach for considering the external networks in the harmonic balance finite-element method they have proposed. The approach is applied to the analysis of a magnetic frequency tripler with circuit elements 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