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Magnetics, IEEE Transactions on

Issue 6 • Date Nov 1996

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Displaying Results 1 - 7 of 7
  • Spectral response nulls for single-pole heads in perpendicular recording

    Page(s): 5277 - 5278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    This letter discusses the dependence of the nulls in the spectral response function of a single-pole head, used in perpendicular magnetic recording with a double-layer medium, upon the pole thickness and the distance between the pole and the underlayer. Exact results from a two-dimensional model are used to produce approximate but accurate relationships, and are compared with previously published theoretical and experimental results where full data are available View full abstract»

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  • NMR of room temperature samples with a flux-locked dc SQUID

    Page(s): 5261 - 5264
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Superconducting quantum interference devices (SQUIDs) are the most sensitive detectors of magnetic fields. Since SQUIDs detect the magnetic flux rather than its rate of change, they can be used to great advantage to measure nuclear magnetic resonance (NMR) signals at low fields and frequencies. We have used a dc (direct-current) SQUID operated in flux-locked mode to significantly improve upon our previous low-field NMR results performed using an RF (radio-frequency) SQUID. The increase in sensitivity gained by using the dc SQUID has helped in reducing the signal acquisition time by a factor of more than 100 compared with our earlier measurements using an RP SQUID. We have also obtained a simple one-dimensional T1-contrasted NMR image of a two-component sample consisting of mineral oil and tap water at room temperature. Our results highlight the sensitivity of the SQUID as an NMR detector and the promise of using SQUIDs in NMR imaging at low fields for both medical applications and for materials' nondestructive evaluation View full abstract»

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  • A crosstalk model considering leakage fluxes and methods to reduce crosstalk between read/write head and pre-erase head

    Page(s): 5271 - 5276
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    A head combined with a read/write (R/W) and a pre-erase gap is adopted for 4 MB flexible disk drives. Reducing the crosstalk coupling between the erase head and the R/W head is an important factor in the design. We developed a simple design method to analyze the crosstalk using a three-dimensional finite-element method (3D-FEM). We found that there are two flux paths contributing to the crosstalk in the reproducing process: one is the path through the ferrite cores, and another is the path fringing and reentering into the R/W core. Balancing the fluxes through these two paths, it was possible to realize both high efficiency and low crosstalk simultaneously, Furthermore, the crosstalk during the recording process was analyzed using dc-bias recording theory View full abstract»

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  • Evaluation of a high-performance magnetically shielded room for biomagnetic measurement

    Page(s): 5256 - 5260
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    A spherical magnetically shielded room called COSMOS and a method for measuring the shielding factor of well-shielded rooms have been developed. A dc-superconducting quantum interference device is used to detect faint magnetic fields, and the detected signals are averaged to increase the signal-to-noise ratio. The measured magnetic shielding factor for COSMOS is 420000 at 1 Hz View full abstract»

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  • Measurement of losses and saturated permeability of saturable cores under submicrosecond saturation

    Page(s): 5251 - 5255
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    Two specific methods are introduced for obtaining accurate losses and saturated permeability of saturable cores under submicrosecond saturation. One employs an additional inductor for accurate measurement of the losses. The other minimizes stray inductance for accurate measurement of the saturated permeability. The measured relative permeability of Co-based amorphous cores rapidly drops to nearly 1.0. On the other hand, ferrite cores need a much larger magnetic field than that for Co-based amorphous cores in order to obtain the relative permeability of 1.0 View full abstract»

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  • A scaling model for the optical anisotropy in magnetic fluids: dichroism and birefringence

    Page(s): 5245 - 5250
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    A simple scaling model for dichroism and birefringence in magnetic fluids is proposed. This scaling is based on two physically measured quantities, i.e. the initial slope of the optical anistropy curve with magnetic field, and the saturation value of dichroism or birefringence. Using this model, the isothermal dichroism and birefringence are superimposed into a single function. This model is discussed and compared with one similar to that proposed for the magnetization of a superparamagnetic particle system View full abstract»

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  • Distortion of inductive read head signal due to side-written magnetization

    Page(s): 5265 - 5270
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    We apply a Fourier series model to calculate distortion in an inductive read head signal due to side-written magnetization patterns in thin-film magnetic recording media. This model predicts that a magnetization pattern consisting of in-track longitudinal and transverse track edge magnetizations will produce a signal distorted by the flux from the side magnetization. By using parameters obtained from a direct magnetic image of the patterns, this analysis predicts the morphology and magnitude of signal distortion as a function of pattern dimensions. The implication of this distortion for higher bit densities suggested for the future was found to be significant. The proposed method will offer reliable means to quantitatively assess the effect of side writing at such densities 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