IEEE Transactions on Magnetics

Issue 5 • September 1985

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Displaying Results 1 - 25 of 235
  • [Front cover and table of contents]

    Publication Year: 1985, Page(s): 0
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  • Conference organization

    Publication Year: 1985, Page(s):1325 - 1326
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  • Industrial contributors

    Publication Year: 1985, Page(s): 1327
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  • Chairman's preface

    Publication Year: 1985, Page(s): 1328
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  • Conference highlights

    Publication Year: 1985, Page(s):1329 - 1331
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    First Page of the Article
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  • Laser doppler interferometry on magnetic recording systems

    Publication Year: 1985, Page(s):1332 - 1337
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (648 KB)

    Laser Doppler interferometry is used to determine the six components of velocity of read/write heads in magnetic disk files. These measurements are made on production drives in which the only alteration is the installation of a window so that the laser beams can be directed onto any of the four corners of the slider. A laser Doppler vibrometer (LDV) is used to measure the out-of-plane velocity of ... View full abstract»

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  • Review of head-media coupling in magnetic recording

    Publication Year: 1985, Page(s):1338 - 1343
    Cited by:  Papers (7)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (592 KB)

    Recent advance of magnetic recording technology has resulted in tremendous increase in area densities. Several new components were developed: Thin film media, and thin film head in longitudinal recording; Single-layer media, double-layer media, and probe head in perpendicular recording. A variety of head and media combinations become possible, and each has a different degree of head-media coupling... View full abstract»

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  • Recording codes for digital magnetic storage

    Publication Year: 1985, Page(s):1344 - 1349
    Cited by:  Papers (120)  |  Patents (30)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (912 KB)

    This paper provides a tutorial introduction to recording codes for magnetic disk storage devices and a review of progress in code construction algorithms. Topics covered include: a brief description of typical magnetic recording channels; motivation for use of recording codes; methods of selecting codes to maximize data density and reliability; and techniques for code design and implementation. View full abstract»

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  • Noise in high performance thin-film longitudinal magnetic recording media

    Publication Year: 1985, Page(s):1350 - 1355
    Cited by:  Papers (133)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (736 KB)

    The problem of noise in thin-film longitudinal media is analyzed experimentally and theoretically. The physical mechanism for the noise is shown to be fluctuations in the geometry of the zig-zag transitions separating bit cells. The shifted-transition noise model is introduced as a means of quantifying the noise processes. Spatial, spectral, and autocorrelation properties are introduced. A calcula... View full abstract»

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  • The synthesis of magnetic recording trellis codes with good hamming distance properties

    Publication Year: 1985, Page(s):1356 - 1358
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (328 KB)

    In this paper we present, by means of an example, a systematic procedure to synthesize combined modulation/error correcting trellis codes, suitable for Viterbi decoding. This synthesis is based on firstly selecting a suitable linear convolutional code, secondly by analysing the state system of this code to determine the important Hamming distance building properties, and finally by mapping a code ... View full abstract»

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  • Transitions on perpendicular rigid disks in quasi-contact

    Publication Year: 1985, Page(s):1359 - 1364
    Cited by:  Papers (6)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (600 KB)

    Results of quasi-contact recording on rigid perpendicular disks are presented in this paper. Footprints of Various recording heads on different recording media, obtained at quasi-static contact conditions using a high resolution magnetoresistive transducer, provide useful information such as sharpness of the magnetization transition and the effect of the demagnetizing field. Very high density magn... View full abstract»

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  • 5.25 inch floppy disk drive using perpendicular magnetic recording

    Publication Year: 1985, Page(s):1365 - 1367
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (280 KB)

    5.25 inch high density perpendicular magnetic recording floppy disk drive has beer developed by employing new types of high saturation magnetization ring head, Co-Cr single layer medium with Ge underlayer, head slider with ellipsoidal surface configuration to assure intimate head to medium contact, and signal equalization. By these combination, recording density D50 of 145 kFCI, peakshift of 28 % ... View full abstract»

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  • High density recording with perpendicular Co-Cr-Nb media and ring heads

    Publication Year: 1985, Page(s):1368 - 1370
    Cited by:  Papers (30)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (256 KB)

    Effective double layer structure was investigated by adding Nb to the sputtering source of Co-Cr thin film perpendicular magnetic recording tapes. The output from the tapes was measured with a ring head through to the short wavelength, λ50=0.19 μm (D50=267KFRPI). View full abstract»

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  • Transversal recording on radially anisotropic disc

    Publication Year: 1985, Page(s):1371 - 1373
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (296 KB)

    Transversal recording has been described in the sixties, as a promising mode to achieve high density magnetic recording [1]. Because of the improvements in longitudinal and vertical recording introduced by thin film technologies for heads and media, research labs took no further interest in this transversal mode, partly due also to the fact that media and heads were not available at that time. How... View full abstract»

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  • The erasure of high energy tapes

    Publication Year: 1985, Page(s):1374 - 1376
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (304 KB)

    In this paper we describe our studies on the erasure of high energy tape. We have found that the bulk degaussers designed for erasing low coercivity tape cannot adequately erase high energy tape. We also show that increasing the strength of the ac erase field is not a practical solution. We then describe the new techniques we have developed to adequately erase high energy tape. These new technique... View full abstract»

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  • Erasure techniques for high-density recording

    Publication Year: 1985, Page(s):1377 - 1379
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    In this study, several erase techniques are examined as to their effect on analog-signal performance in high-density digital magnetic recording. The success of an erasure technique was found to depend on the coercivity of the tape and whether the read-back head senses dφ/dt or flux. View full abstract»

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  • Overwrite as a function of record gap length

    Publication Year: 1985, Page(s):1380 - 1382
    Cited by:  Papers (28)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (504 KB)

    In disk recorders, a common head is used for both recording and reproducing. Old data are not erased but are simply recorded over. The partially erased old data signal appears in the new data as error-producing interference. The amount of erasure of the old data signal is called "overwrite", and 30 dB is typically required. To avoid the reproduce gap null, the head gap is usually chosen to be less... View full abstract»

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  • Roughness and recording properties of particulate tapes: A quantitative study

    Publication Year: 1985, Page(s):1383 - 1385
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (344 KB)

    Recording properties such as modulation noise and output are known to be strongly influenced by the surface roughness of the magnetic coating. On the basis of a simple two-dimensional model for the contact between magnetic head and coating we are able to account for the roughness effects quantitatively. The head-tape distance is used as an intermediate parameter. Our model was successfully tested ... View full abstract»

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  • Relationship of surface roughness of video tape to its magnetic performance

    Publication Year: 1985, Page(s):1386 - 1388
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (376 KB)

    The surface roughness, known to influence the recording and play-back properties of magnetic recording media, was interferometrically measured of a series of VHS video tapes. A strong correlation (r>.95) was found between both the signal outputs and noise of these tapes with rms surface roughness. The measured short waveloength rf output was shown to decrease with increasing surface roughness i... View full abstract»

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  • Noise autocorrelation in magnetic recording systems

    Publication Year: 1985, Page(s):1389 - 1391
    Cited by:  Papers (19)  |  Patents (13)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (360 KB)

    This paper describes a new technique for measuring the noise autocorrelation in magnetic recording systems. Unlike the spectrum, the autocorrelation function characterizes non-stationary noise as well as stationary noise so it is particularly suitable for signal dependent noise often found in disks. In addition, noise sources can be separated by properly choosing the sample space. Many interesting... View full abstract»

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  • Dropout-error-rate calculations for a maximum-density study

    Publication Year: 1985, Page(s):1392 - 1394
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (376 KB)

    This paper describes an experimental method for determining the maximum areal density achievable for a given head-to-tape interface (HTI). Using this method, we can calculate amplitude and bit-shift error rates during dropouts for the areal density the HTI is originally designed for, and beyond. First, the read-back waveform is sampled to obtain the amplitude distribution of signal samples below 5... View full abstract»

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  • Interpretation of spectral response in perpendicular recording

    Publication Year: 1985, Page(s):1395 - 1397
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (312 KB)

    A previously published voltage spectrum in perpendicular recording is analyzed here utilizing the exact fields of a probe head and keepered medium. It is concluded that sharp transitions have been written at a negligible spacing. Previous analysis which utilized a duality between a ring head and a probe-keeper head yielded a non-zero spacing or recorded transition length. Measurements of D50<... View full abstract»

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  • Analytical modelling of perpendicular recording

    Publication Year: 1985, Page(s):1398 - 1400
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (352 KB)

    An analytical model for perpendicular magnetic recording is presented which is capable of calculating 'ab-initio' the magnetisation distributions written by an 'arbitrary' head field into both single and double layer recording media. Magnetisations are shown to follow the head field distribution existing at the medium's top surface. Application of the theory allows prediction of many of the fundam... View full abstract»

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  • A comparison of longitudinal and perpendicular recording based on optimum perpendicular transition

    Publication Year: 1985, Page(s):1404 - 1407
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (432 KB)

    This paper describes an idealized magnetic transition that results in optimum performance for perpendicular magnetic recording systems. This transition has a step at its center, and its magnetic moment is the maximum allowed when the perpendicular demagnetizing field at the coating surface is limited to Hc. System performance is modelled by the timing margin for a 10-10error ... View full abstract»

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  • On the transition length in perpendicular recording

    Publication Year: 1985, Page(s):1401 - 1403
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (264 KB)

    Using the analytical model previously described by the authors [1],[2], magnetization transitions and transition lengths are calculated as a function of relevant physical parameters. When a probe head is used to record on a medium with a permeable under-layer, the readback voltage and the transition length are determined mostly by the head-medium separation. The calculated results agree with exper... View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics is a peer-reviewed, archival journal in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage. The journal publishes scholarly articles of archival value as well as tutorial expositions and critical reviews of classical subjects and topics of current interest.

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Meet Our Editors

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