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Magnetics, IEEE Transactions on

Issue 10 • Date Oct. 2006

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Displaying Results 1 - 25 of 457
  • [Front cover]

    Publication Year: 2006 , Page(s): c1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2006 , Page(s): c2
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  • Table of contents

    Publication Year: 2006 , Page(s): 2229 - 2251
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  • Intermag 2006 Chairman's Foreword

    Publication Year: 2006 , Page(s): 2252
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  • Intermag 2006 Publication Chair's Preface

    Publication Year: 2006 , Page(s): 2253
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  • Intermag 2006 Exhibitors

    Publication Year: 2006 , Page(s): 2254
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  • Recording on Bit-Patterned Media at Densities of 1 Tb/in ^2 and Beyond

    Publication Year: 2006 , Page(s): 2255 - 2260
    Cited by:  Papers (119)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    We present a comprehensive analysis of the areal density potential of a bit-patterned media recording. The recording performance is dominated by written-in errors rather than traditional signal-to-noise considerations. Written-in errors are caused by statistical fluctuations of the magnetic properties and the locations of the individual dots. The highest areal densities are obtained with a combination of a pole head, a soft magnetic underlayer, and a storage medium of the composite type. Areal density scenarios of up to 5 Tb/in2 are analyzed View full abstract»

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  • Measurement of Down-Track Correlation for Perpendicular Magnetic Media With Various Inter-Granular Exchange Coupling

    Publication Year: 2006 , Page(s): 2261 - 2263
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (258 KB) |  | HTML iconHTML  

    In order to attain high track density, track-edge noise was studied in conjunction with the fine magnetic structure of perpendicular media. The track-edge noise was increased in media with stronger exchange coupling. The down-track correlation length was measured and compared with the cross-track correlation length. The track-edge noise and correlation length depended upon the inter-granular exchange coupling of the media. Magnetic isolation of grains and steep head field gradient along the cross-track direction is expected to improve the write resolution at the track-edges View full abstract»

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  • Effect of Write Current Waveform on Magnetization and Head-Field Dynamics of Perpendicular Recording Heads

    Publication Year: 2006 , Page(s): 2264 - 2266
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    The response of perpendicular magnetic recording heads with a single turn and two turn coils is calculated using a full micromagnetic model, including return pole and soft underlayer. We study the effect of coil current waveforms with different rise times and overshoots. For fast coil current rise times, the head field shows very little response, until the coil current changes its polarity and it is limited by the intrinsic magnetization dynamics. Even the effect of overshoot is limited by the same mechanism. Shorter yoke length and coil turns close to the air-bearing surface improve the head-field dynamics View full abstract»

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  • Observation of Recording Pole Instability in Perpendicular Recording

    Publication Year: 2006 , Page(s): 2267 - 2269
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (778 KB) |  | HTML iconHTML  

    Down- and cross-track distributions of medium magnetization are determined by the recording pole field profile and the switching dynamics. Earlier studies of the write pole footprint in perpendicular magnetic recording revealed asymmetrical media saturation caused by magnetic pole nonuniformity. In this paper, we report variable footprint shapes indicating recording pole instability. We extend our spin-stand "footprint" measurements to also evaluate recording pole instability View full abstract»

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  • Spinstand Measurement of Head Keeper Spacing in Perpendicular Recording

    Publication Year: 2006 , Page(s): 2270 - 2272
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB) |  | HTML iconHTML  

    Head keeper spacing (HKS) is an important parameter in the keepered perpendicular magnetic recording. In this paper, a nondestructive method to measure HKS from the playback waveform of a specific recording pattern was proposed. Time and frequency domain techniques can be utilized for the measurements. The measured HKS was shown to be consistent by using different playback harmonic peaks. The effect of head surface potential distribution due to the HKS change was also discussed View full abstract»

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  • The Magnetic Spacing Sensitivity of Perpendicular Recording

    Publication Year: 2006 , Page(s): 2273 - 2275
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    Perpendicular and longitudinal hard disk drives are compared in terms of their sensitivity to magnetic spacing. The heads in both drives have the same air-bearing design. When the ambient pressure is changed, both drives respond with the same change in spacing. The relative change in soft error rate and SNR as a function of spacing is the same for both types of drives. In addition, spacing is measured directly as a function of pressure. The Wallace spacing loss gives similar results for both designs in the limit where the reference wavelength is small relative to the distance between the head and the soft underlayer. The Wallace formula agrees as well with the hyperbolic formula that includes the effect of an ideal soft underlayer View full abstract»

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  • Fast Calculation of Read Field From Perpendicular Recording Medium Using Head Characteristic Matrix

    Publication Year: 2006 , Page(s): 2276 - 2278
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB)  

    A very fast calculation method of calculating the three-dimensional read head field from a perpendicular recording medium is presented using a head characteristic matrix K, and the medium charge with a spacing loss correction. The numerical integration in the evaluation of the matrix can be replaced with an infinite sum, speeding up the calculation significantly. The head characteristic matrix has a physical significance as the inverse matrix of the self-magnetostatic energy with a charge placed on the air bearing surface (ABS) of the read gap View full abstract»

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  • Direct Solution of Medium Field and Cross-Track Characteristics of Read Sensors

    Publication Year: 2006 , Page(s): 2279 - 2281
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    This paper describes a direct calculation method for medium fields in perpendicular recording systems. The method accounts for the effect of the zig-zag transition in the written medium pattern which can be obtained using micromagnetic simulations. The described method is useful for studying the cross-track characteristics of read sensors. The method is able to deal with a recording medium layer with nonunity relative permeability. The computed medium field in the gap region under the read head is compared with that obtained using the finite-element method. The purpose of this study is to develop a fast and effective tool for producing read-back signals based on computer modeling and simulation View full abstract»

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  • The 2-D Hilbert Transform in Magnetic Recording

    Publication Year: 2006 , Page(s): 2282 - 2284
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (82 KB) |  | HTML iconHTML  

    The generalization of the Hilbert transform for three-dimensional magnetic fields in magnetic recording is presented. This generalization is based on the simultaneous use of "magnetic charge" and "electric current" models of the recording media. The Fourier representation of the 2-D Hilbert transform is discussed, along with its unique scaling properties View full abstract»

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  • The Influence of Bit Patterned Medium Design and Imperfections on Magnetoresistive Playback

    Publication Year: 2006 , Page(s): 2285 - 2287
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (121 KB) |  | HTML iconHTML  

    Magnetoresistive playback off bit patterned magnetic recording media is studied. Three playback configurations are compared: not shielded sensors, shielded sensors commonly used in magnetic recording systems, and shielded differential sensors. Influence of patterned medium parameters including bit-filling ratio, bit shape, bit position jitter, bit-size variation on the playback signal is studied. Playback signal amplitude, D50, and signal-to-noise ratio are used to compare different playback sensor configurations. It is found that in general, shielded differential readers offer superior performance as compared to both shielded single sensor readers and not shielded readers View full abstract»

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  • Micromagnetic Modeling of Track Squeeze and Erasure Versus Skew Angle

    Publication Year: 2006 , Page(s): 2288 - 2290
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    Micromagnetic modeling of adjacent track squeeze in perpendicular magnetic recording, and its effect on track density was studied as a function of skew angle. Based on amplitude 747 curve of track squeeze and reader off track capability of 10%, a loss of 6.5% of track density was predicted by micromagnetic model for head of 150 kTPI track density. The analysis also shows that erase width is smaller than magnetic write width and erase width formula based on pole geometry overestimates the effect of track density loss due to skew angle View full abstract»

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  • Influences of Thermal Fluctuations on Recorded Magnetizations During Recording Process

    Publication Year: 2006 , Page(s): 2291 - 2293
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (951 KB) |  | HTML iconHTML  

    The recording process is examined by computer simulation to clarify the reason why magnetic recording at a linear recording density of over 2000 kFCI is difficult in perpendicular magnetic recording. The recording medium is found to suffer from strong thermal fluctuations, even during the recording process. The recorded magnetization of the preceding recorded bit is decreased considerably by the reversed head field to write the succeeding bit. Numerical results show that this decrease is not due to normal recording loss, but rather to the thermal fluctuations that is enhanced by the reversed trailing field of the SPT head. Based on the results obtained herein, recording at over 2000 kFCI is believed to be possible by reducing the trailing field strength of the SPT head View full abstract»

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  • Thermal Reversal of Magnetic Grains Under Time Varying Pulse Field

    Publication Year: 2006 , Page(s): 2294 - 2296
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (178 KB)  

    Media thermal magnetization switching under an arbitrary time varying field, pulse shape, and duration is an important issue in many recording applications. This paper shows a scale dilemma in using the time dependent energy barrier approach to describe long time thermal reversal of magnetic grains under a time varying pulse field. A new model approach based on an optimal reversal path is proposed to characterize the thermal reversal behavior of magnetic grains under an arbitrary time varying pulse field. Using this new model approach, the effects of pulse field duration, width, and amplitude on magnetic grain thermal switching behavior are studied View full abstract»

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  • Optimization of Precompensation for NLTS in Perpendicular Magnetic Recording

    Publication Year: 2006 , Page(s): 2297 - 2299
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB) |  | HTML iconHTML  

    Nonlinear transition shift (NLTS) and nonlinear amplitude distortion (NLAD) in perpendicular magnetic recording were investigated for CoPtCr-SiO2 media with various SiO2 contents that have various inter-granular exchange coupling. The tighter inter-granular coupling increases both NLTS and NLAD. The NLTS and NLAD were discriminated and extracted NLTS showed that perpendicular media exhibited the opposite shift to longitudinal media as theoretically expected. Careful precompensation optimization is required to obtain a good error-rate performance at high-linear densities View full abstract»

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  • Transition Curvature Assessment for High TPI Applications

    Publication Year: 2006 , Page(s): 2300 - 2302
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Transition curvature is a growing concern for high tracks per inch application. Due to low resolution from the playback transducer in cross track direction, the characterization of the transition edge is very difficult. This situation increases the engineering difficulty for writer pole design optimization and recording performance analysis. We have derived a simple transition shape model to study the transition curvature quantitatively. The complicated transition edge is simplified into one curving parameter. With such simplification, we are able to relate the transition curving effect with the cross track profile. In this paper, we will discuss the concept and analytical derivation of this model. A particular H/M combination is studied and its transition curvature is estimated. Compared with magnetic force microscope and micromagnetic modeling, this new approach has potential to become a practical spinstand or even Hard disk drive measurement if the W/R nonlinear effects are minimized View full abstract»

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  • Side Shielded TMR Reader With Track-Width-Reduction Scheme

    Publication Year: 2006 , Page(s): 2303 - 2305
    Cited by:  Papers (2)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (503 KB)  

    A track width reduction and an area resistance (RA) reduction scheme are presented to meet the requirement of the reader for ultrahigh density recording. The side reading effect worsens the performance of the track-width-gradient-reduction design even if a side-shield layer is applied due to the overlap between the backend and the side-shield. However, the side-reading effect can be significantly suppressed in the long-height design after the introduction of the side-shield. Using the long-height sensor design, the RA, the track width and the signal level may meet the requirement of reader for ultra-high density recording. The back flux-guide design can further improve the sensitivity of the tunneling magneto resistance (TMR) sensor View full abstract»

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  • Effects of Deposition Rate on Microstructure of CoCrPt-SiO _2 Granular Longitudinal Media for Tape Applications

    Publication Year: 2006 , Page(s): 2306 - 2308
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1003 KB) |  | HTML iconHTML  

    The microstructure of sputtered CoCrPt-SiO2 media for tape applications was investigated under different deposition rates. Plan-view and high-resolution cross-sectional TEMs were used to observe the media growth morphology and oxide phase separation behavior. Additionally, time-dependent magnetic property measurements were used for switching volume determination. Although plan-view TEM images suggested well-isolated, small grains, cross-sectional TEM images and switching volume measurements revealed magnetic interconnection between the apparent "grains" visible in the plan-view images. When the deposition rate was reduced from 0.28 to 0.05 nm/s, TEM images showed larger features in plan-view, which is consistent with greater time for atomic motion on the surface before burial. It was also observed in cross-sectional TEM images that columnar growth at the higher rate changed to spheres of metal in an SiO2 matrix at low deposition rate View full abstract»

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  • Evolution With Temperature of the Magnetic Anisotropy of Ba Ferrite Particles

    Publication Year: 2006 , Page(s): 2309 - 2311
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    The magnetic anisotropy of pure and Co/Ti-doped Ba ferrite particles is analyzed through the evaluation of the dependence on temperature of the constants of magnetocrystalline and shape anisotropy, which both are present in the platelet-like Ba ferrite particles with hexagonal structure. In undoped Ba ferrite, the magnetocrystalline anisotropy constant is predominant on the conflicting shape anisotropy constant at all temperatures, which indicates that the magnetic anisotropy is uniaxial, with preferred direction for the magnetization along the c axis of the hexagonal particles. In doped particles, where the magnetocrystalline anisotropy is weakened by the ionic substitutions, while at high temperatures the magnetic anisotropy is substantially uniaxial with c as axis of easy magnetization, when the temperature decreases, the shape anisotropy constant becomes larger than the magnetocrystalline anisotropy constant, and consequently, the magnetic anisotropy is not uniaxial, but it presents multiple preferred directions for the magnetization View full abstract»

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  • A Recording Density Study of Advanced Barium-Ferrite Particulate Tape

    Publication Year: 2006 , Page(s): 2312 - 2314
    Cited by:  Papers (20)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1353 KB) |  | HTML iconHTML  

    A magnetic tape with a 65-nm-thick magnetic layer containing fine barium-ferrite particles was produced using an advanced precision coating process. Using a giant magneto-resistive head on a drum tester, a signal-to-noise ratio of 23.5 dB was achieved at a linear density of 200 kfci, indicating the feasibility of approximately 7 Gb/in2 recording density 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