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Magnetics, IEEE Transactions on

Issue 6 • Date November 1981

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Displaying Results 1 - 25 of 298
  • [Front cover and table of contents]

    Publication Year: 1981 , Page(s): 0
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    Freely Available from IEEE
  • General chairman's message

    Publication Year: 1981 , Page(s): 2515
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    Freely Available from IEEE
  • Some unresolved problems in magnetism

    Publication Year: 1981 , Page(s): 2516 - 2519
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  • Development of garnet science in France

    Publication Year: 1981 , Page(s): 2520 - 2524
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  • Electrographic magnetic stylus recording; A high speed non-impact magnetic printing process

    Publication Year: 1981 , Page(s): 2525 - 2528
    Cited by:  Papers (1)
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    An electrographic magnetic printing process is described which uses magnetically attractable and electronically conductive dry toner material deposited directly onto a dielectric layer in response to electronic current flow from one member of an array of magnetically permeable styli. The imaging process is extremely flexible in imaging speed, dot/mm resolution, continuous grey scale, and materials. View full abstract»

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  • High resolution recorder for magnetic printing

    Publication Year: 1981 , Page(s): 2529 - 2531
    Cited by:  Papers (1)  |  Patents (1)
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    A high resolution rotating head recorder for generating magnetic latent images on magnetic tape for magnetographic printing is described. The device is capable of recording a full 8.5 by 12 inch page with a resolution of up to 1000 dots per inch. It is designed as an experimental tool for investigating the halftone reproduction capability and speed and quality limits of magnetography. A detailed description of the device is given and its operating characteristics are discussed. View full abstract»

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  • A new thin film scanning head for magnetic printing

    Publication Year: 1981 , Page(s): 2532 - 2534
    Cited by:  Papers (1)
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    Magnetic printers are subject to serious limitations, due either to the requirement to move the printing head, or to use multiple heads. The purpose of this paper is to describe the principle of a new head which allows a microline to be recorded by scanning a stress in a head which has magnetostrictive pole pieces. Stress characteristics are described and the changes in the magnetic behaviour of two suitable stress sensitive magnetic alloys are given. Finally, the head limitations are discussed. View full abstract»

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  • Wavelength response of perpendicular magnetic recording

    Publication Year: 1981 , Page(s): 2535 - 2537
    Cited by:  Papers (32)
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    From the measurements of the surface field of a recording medium, it was obtained that an almost ideal step change distribution of magnetization is formed in perpendicular recording for digital signals. The fact represents that the upper limit of usable recording density is determined only by the resolution of a reproducing head. Therefore, the reproduction by a perpendicular head was successfully analyzed by using the reciprocity theorem. By introducing thickness loss of main pole of the head, the satisfactory coincidence was obtained between the calculated and the measured results in the wavelength response even at the densities of more than 150 kMRPI. In reproducing process, the magnetic interaction between the main pole and the medium acts so as to decrease the effective spacing between them. View full abstract»

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  • Perpendicular magnetic recording performance of double-layer media

    Publication Year: 1981 , Page(s): 2538 - 2540
    Cited by:  Papers (13)
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    Perpendicular magnetic recording performance for double-layer (Co-Cr,Ni-Fe) media was analyzed, with a simple magnetization model, in comparison with single-layer media. The calculated output voltage from a ring-shaped reproducing head shows good agreement with experimental data. It is shown theoretically and empirically that the Co-Cr layer thickness can be reduced without sacrificing the output amplitude, if the Ni-Fe layer is placed underneath it to perform as a "flux sink" to extinguish the rear surface charge on the Co-Cr layer. View full abstract»

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  • Large scale model studies of vertical recording

    Publication Year: 1981 , Page(s): 2541 - 2543
    Cited by:  Papers (1)
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    A large scale magnetic recording model (5000x) has been used to study writing and reading using a film ring head on a medium which can be configured in either a horizontal or vertical recording mode. Field measurements from the written transitions indicate that a narrower transition is written on the vertical medium configuration than on the horizontal. View full abstract»

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  • Fundamental properties of perpendicular magnetic recording

    Publication Year: 1981 , Page(s): 2544 - 2546
    Cited by:  Papers (5)
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    A two dimensional computer simulation model of the magnetic recording process has been, developed to assess the fundamental properties of perpendicular magnetic recording. It was found that vertical anisotropy media are well suited to abrupt and closely spaced magnetic transitions. The demagnetizing fields support short transitions in the perpendicular mode as opposed to degrading transitions in the longitudinal mode. However, gapped heads may have difficulty in delivering high intensity vertical fields to saturate the medium. Novel write head designs might be required. View full abstract»

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  • Recording on perpendicular anisotropy media with ring heads

    Publication Year: 1981 , Page(s): 2547 - 2549
    Cited by:  Papers (14)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    This paper reports experimental studies directed at the application of ring head structures to a perpendicular recording system. The media tested were sputter deposited films of CoCrTa alloys. Ferrite heads were studied, but the thin film head was chosen for evaluating roll-off, overwrite, and superposition. The data presented in the paper demonstrates the potential of high density recording with a single layer medium with perpendicular magnetic anistropy and a thin film head separated by 0.20 micrometers. View full abstract»

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  • Switching field distribution and A.C. bias recording parameters

    Publication Year: 1981 , Page(s): 2550 - 2552
    Cited by:  Papers (8)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    A set of tapes has been prepared for audio recording measurements by mixing cobalt modified iron oxides for equal coercivity and remanence but varying switching field distribution (SFD). At low level recording the optimum high frequency bias current but not the maximum signal level was found to decrease with increasing SFD. The long wavelength output at 5% third harmonic distortion remains unchanged. The decrease of short wavelength saturated signal with increasing SFD was separated into demagnetization and bias current losses. View full abstract»

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  • Field measurements near high-density statically recorded transitions in a thin-film medium

    Publication Year: 1981 , Page(s): 2553 - 2555
    Cited by:  Papers (2)
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    A controllable static recording technique which allows transitions to be spaced as closely as 0.25 micron has been used to record isolated and doublet transitions on a thin-film medium. The perpendicular demagnetizing fields from these transitions have been measured with the high-resolution Hall-probe measurement system, and the results were compared to theoretically predicted fields using both the Dynamic Iterative Model and superposition of two isolated arctangent transitions. Both of these theories adequately describe the measured results for this thin-film medium. View full abstract»

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  • Influence of R1parameter {=Fe2O3/(Y2O3+ Sm2O3+ Lu2O3)} on magnetic bubble properties of (YSmLuCa)3(FeGe)5O12

    Publication Year: 1981 , Page(s): 2556 - 2558
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    The influence of R1{=Fe2O3/(Y2O3+Sm2O3+Lu2O3)} in the melt composition on film properties, and growth characteristics, has been investigated for (YSmLuCa)3(FeGe)5O12. The garnet phase is the primary phase when R1is kept between 10 and 60. The temperature coefficient for the bubble collapse filed changes from -0.29 to -0.19 %/°C, and the growth rate with 10°C supercooling changes from 0.60 to 0.15 μm/min, by increasing R1=10 to 60. Distribution coefficients, KY, KSm, KLuand KGeincrease, and KFeand KCadecrease, with increasing R1. View full abstract»

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  • Uniaxial and cubic anisotropy constants in ion-implanted Sm,Tm,Ga:YIG bubble thin films

    Publication Year: 1981 , Page(s): 2559 - 2561
    Cited by:  Papers (2)
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    The effects of ion implantation into (SmTmY)3(GaFe)5O12garnet thin films have been studied by ferromagnetic resonance. He+ ions were used for implantation with doses ranging from 3 to 4 × 1015He+/ cm2and implantation energy ranging from 150 to 175 Kev. The uniaxial and cubic anisotropy constants have been studied as a function of temperature from 0°C to 100°C for both as-grown and ion-implanted films. The implantation has effectively changed an easy-axis anisotropy to that of an easy plane in the implanted layers of the films. A cubic anisotropy constant K1with values varying from 4 × 103to 6 × 103erg/cm3at room temperature has been observed in these films. The results also indicated that to the first order, the implanted region in the film was essentially magnetically uncoupled from the bulk of the film. View full abstract»

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  • Laser annealing of gallium-substituted garnet epitaxial films in pressurized oxygen

    Publication Year: 1981 , Page(s): 2562 - 2564
    Cited by:  Papers (2)
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    The effects of laser annealing Ga-substituted EuYIG epitaxial films in still, controlled ambients of air and one to five atmospheres of pure oxygen have been studied. An approximately logarithmic increase in saturation magnetization ( 4\pi M_{s} ) and decrease in film magnetic Q factor were observed with increasing oxygen pressure in the annealing ambient. Compared with the most successful previous experiments, annealing at five atmospheres of oxygen displaced nearly twice the fraction of Ga from tetrahedral to octahedral lattice sites. As evidenced by the lack of film damage, the correlation of lattice parameter with the location of the Ga ions and the lack of broadening in the ferromagnetic resonance (FMR) lines, effective annealing temperatures above 1850K were achieved with no significant loss of oxygen from the films. The use of FMR to deduce the extent of film annealing was affirmed through the agreement of independent measurements of 4\pi M_{s} by bubble statics and SQUID magnetometry in films indicated to be homogeneous by FMR. View full abstract»

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  • The influence of neutron and gamma irradiation in bubble garnet films

    Publication Year: 1981 , Page(s): 2565 - 2567
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    The behaviour of garnet films, containing 3 micronsbubbles, exposed to neutron irradiation and gamma rays is reported. The implanted and non implanted (YSmLuCa)3(FeGe)5O12epitaxial garnet films were irradiated with fast neutrons (1015n/cm2) and 108rad (Si) gamma rays with 1 MeV energy. In these harsh conditions, the variations of physical characteristic parameters were analysed. In ion implanted films, the coercive field increased from 0.3 to 0.4 oe after neutron irradiation. The gamma rays irradiation brought the strip width back to the value it had before the ion implant. The anisotropy field increased slightly (3%) under both irradiations. The decrease in operating margins of 64 K bit memory chips is presented and a good correlation is made with the previous results. These effects are explained by general phenomena describing the interaction between the irradiation and the material. These experiments show that bubble memories will only fail at a high level of neutron and gamma ray exposure. View full abstract»

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  • A boundary integral equation method for high frequency eddy currents

    Publication Year: 1981 , Page(s): 2568 - 2570
    Cited by:  Papers (5)
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    The authors present a new method to compute the current distribution at the surface of a conducting piece in a high frequency varying field. This method uses boundary integral equation techniques and allows at a very low computing cost to define in three dimensions the hot and cold parts of such a piece before case hardening. The integral equations have to be solved only on the boundary, so the number of dimensions of the mathematical problem is reduced from three to two. Results of current distribution on the surface of a complicated shape piece as a toothed gear are given as an example. View full abstract»

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  • Singularity/integral equation method development for 3-D electromagnetic field calculation

    Publication Year: 1981 , Page(s): 2571 - 2573
    Cited by:  Papers (1)
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    A new integral equation formulation for solving general 3-D electromagnetic field problems using the method of singularities is briefly described. Detailed expressions of integral equations for axially symmetrical open and confined field cases derived from the basic general 3-D formula are given. Mathematical singularities encountered in the equations are analytically removed and an iterative solution procedure is adapted. Numerical results obtained for several test cases during the developmental stage of this method are presented. View full abstract»

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  • A hybrid finite element-boundary integral formulation of Poisson's equation

    Publication Year: 1981 , Page(s): 2574 - 2576
    Cited by:  Papers (13)
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    A method is presented for the solution of two-dimensional static fields in which any region in the plane can be represented by finite elements or by a boundary integral. The form of the set of simultaneous equations obtained is studied and several illustrative examples of the technique are given. View full abstract»

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  • Iron losses calculation in non-oriented steel plate

    Publication Year: 1981 , Page(s): 2577 - 2579
    Cited by:  Papers (2)
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    This paper describes a method of calculating the iron losses from few macroscopic experiments, for non-oriented steel plate with sinusoidal magnetisation, taking into account saturation and hysteresis. With macroscopic considerations, iron losses are calculated using Poynting vector and Maxwell's equations, and can be separated into two components: hysteresis and eddy current losses. These losses are studied by resolution of the non-linear system equation associated to hysteresis simulation by the Preisach model. Calculations are applied to non-oriented Fe-Si steel plates and compared with experimental results obtained on Epstein apparatus for a wide range of frequencies and flux densities. View full abstract»

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  • Boundary integral equation solution of the single sided linear induction pump problem

    Publication Year: 1981 , Page(s): 2580 - 2582
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    This paper utilizes the Boundary Integral Equation Method to analyse the single sided linear induction pump. The advantage offered by the method is that transverse edge effects are not neglected. The equations necessary for the electromagnetic field and force analysis of the pump are developed and the numerical solution of the equations is described. Particular attention is given to means of calculating the electromagnetic fields within the molten metal secondary. Typical field and force distributions are presented. View full abstract»

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  • Electromagnetic field solution for a coil of arbitrary shape moving relative to a set of ferromagnetic layers

    Publication Year: 1981 , Page(s): 2583 - 2585
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    A general method is described for solving the electromagnetic field problem associated with a coil of arbitrary shape moving above a number of planar ferromagnetic layers. It is shown that power and the 3-axis forces may be determined using a Fourier transform technique, together with a transmission line analogue. If only power and the 3-axis forces are required, and not the actual field components, then the use of the inverse Fourier transforms can be obviated by utilising the Parseval identity. The method is illustrated with a simple example. View full abstract»

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  • An accurate method of calculating multilayer, multimaterial cylindrical magnetic shields

    Publication Year: 1981 , Page(s): 2586 - 2588
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    The basic concepts of shielding theory have existed since the last century [1,2]. There have been many publications on the subject of magnetic shielding, treating the case of shielding apparatus from static fields by means of multiple concentric shields and deriving several principles of fundamental importance. Unfortunately, however, theory has been applied to only the most ideal shield configurations, for the case of constant permeability [3-5]. This paper covers the analysis of shielding effectiveness of variable Permeability cylindrical shielded enclosures for the DC magnetic field case. When the permeability is a function of magnetic induction, the simple boundary solution for spherical or cylindrical shields can no longer be applied since the induction, through the permeability, is caused to vary as much as two orders of magnitude, causing nonuniformity in the field in the cavity and inside the shield. Thus, the permeability of the shielding material is considered as a function of the induction, and a significantly improved method of estimating the induction and permeability of the shield is presented. The effects of a multiple-shell geometry are treated in the equations of this analysis. This method gives fast, accurate results and can be run on a small computer for shielding optimization. Results of these magnetic field calculations allowed the selection of optimization criteria and showed how system requirements could be met by choosing a suitable shell structure arrangement. Experimental measurements on real materials for various shell structures confirmed the accuracy of this method. 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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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology