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Magnetics, IEEE Transactions on

Issue 1  Part 2 • Date Jan 2001

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Displaying Results 1 - 14 of 14
  • IEEE Magnetics Society Distinguished Lecturers for 2001-2002

    Publication Year: 2001 , Page(s): 514 - 516
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    Freely Available from IEEE
  • Piecewise linear model for field-responsive fluids

    Publication Year: 2001 , Page(s): 558 - 560
    Cited by:  Papers (5)
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    The Frohlich-Kennelly model provides a constitutive law for saturation that is field dependent and has been widely used for studying nonlinear properties for a variety of electric and magnetic applications. Under the Frohlich-Kennelly model, saturation begins to occupy the entire conducting domain even at low-moderate applied fields, in this paper, we first present a new nonlinear constitutive law for field-responsive fluids that depends on the local fields and allows regions where the fields have not reached a critical value to remain unsaturated. We then study numerically the nonlinear saturated model and compare the results to the Frohlich-Kennelly model and experiments performed at the Lord Corporation, Cary, NC View full abstract»

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  • Pinning and minor loops in an inclusive model of ferromagnetic hysteresis

    Publication Year: 2001 , Page(s): 517 - 521
    Cited by:  Papers (1)
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    Pinning and minor loops are treated in an inclusive macroscopic model of ferromagnetic hysteresis. The model is developed from a Stoner-Wohlfarth approach and includes pinning effects, like the Jiles-Atherton model, Complicated sets of field turning points, typical of the Preisach model, are included. The extensions made here to the Stoner-Wohlfarth model, particularly the pinning effects, constitute a hypothetical study of ferromagnetism within the confines of an idealized numerical model, and do not necessarily correspond to the behavior of known magnetic materials. Computational approaches to two-dimensional calculations are outlined and results are given. The minor loops are seen to exhibit incongruence and eventual closure View full abstract»

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  • Techniques for minimizing error propagation in decision feedback detectors for recording channels

    Publication Year: 2001 , Page(s): 592 - 602
    Cited by:  Papers (8)  |  Patents (9)
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    Decision feedback equalization (DFE) is a low-cost approach for signal detection in magnetic recording channels. However it suffers from the phenomenon of error propagation (EP). In this paper two approaches are proposed for minimizing EP in DFE. The first approach imposes appropriate constraints on the feedback equalizer. The second approach uses simple threshold techniques to detect the presence of decision errors and to either correct these errors or minimize the possibility of further errors. Computer simulations show that the proposed techniques reduce EP very significantly. Theoretical analyses of the threshold techniques are presented to quantify the associated false and correct detection probabilities. By combining the analysis with an existing EP simulation method, a fast simulation procedure is derived for estimating EP and bit error rate (BER) View full abstract»

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  • Orientation dependence of the dynamic coercivity of Stoner-Wohlfarth particles

    Publication Year: 2001 , Page(s): 533 - 537
    Cited by:  Papers (14)  |  Patents (1)
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    The time dependence of the remanent coercivity for noninteracting Stoner-Wohlfarth particles with uniaxial anisotropy has been calculated numerically as a function of easy axis angle and distribution width. The results have been interpreted in terms of a simplified effective energy barrier function of the form ΔE=CKV(1-H/H0)n and a modified Sharrock equation. For a system with identical easy axis angles, Sharrock law behavior occurs at all angles over a wide range of times with C=1 and n a function of angle. For a distribution of easy axes, Sharrock law behavior also occurs with C=1 and n≈1.5 for squareness values ranging from random to at least 0.98. The dependence of the energy barrier on field and easy axis angle is compared with the Victora expansion and with the Pfeiffer model View full abstract»

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  • Modeling the Lorentzian magnetic recording channel with transition noise

    Publication Year: 2001 , Page(s): 583 - 591
    Cited by:  Papers (22)  |  Patents (6)
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    This paper derives closed-form expressions for modeling a magnetic recording channel with transition noise. The closed-form expressions assume matched filtering, a Lorentzian transition response, and a first-order position jitter and width variation model. The result is a model that is straightforward and easy to use for simulation and analytical purposes. From the model, equations are derived for partial response targets of constrained length that minimize mean squared error in the presence of transition noise. Simulation results for the resulting targets in various transition noise environments are also included, along with a discussion of the results View full abstract»

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  • Magnetization reversal processes in exchange-biased spin-valve structures

    Publication Year: 2001 , Page(s): 565 - 570
    Cited by:  Papers (10)
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    In this paper we provide an initial, qualitative description of the basic magnetization reversal processes that occur when a soft ferromagnetic layer is coupled to an antiferromagnet. We find that the magnetization reversal in the ferromagnetic layer adjacent to the antiferromagnet, i.e., the pinned layer, is dominated by thermal activation processes, We have developed, and report here, a model that accounts for seven distinct features of the magnetization curve of the pinned layer. The model is based upon the formation of domains in the antiferromagnetic layer whose growth is dominated by thermal activation processes. The thermal activation of these domain processes can result in shifts of the hysteresis loop in either direction, depending on the magnetic history of the sample and the rate of field sweep, In consequence, we call into question the current definition of the exchange field Hex typically used to characterize such systems View full abstract»

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  • Time-domain simulation of mixed nonlinear magnetic and electronic systems

    Publication Year: 2001 , Page(s): 522 - 532
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    This paper describes a technique for the simulation of complex magnetic systems intimately connected to any necessary drive electronics. The system is split into two Kirchhoffian domains, one magnetic and one electric. Two-way interaction between the domains is supported by a virtual device called a magnetoelectric differential gyrator. With this technique, arbitrarily complex, nonlinear, hysteretic magnetic systems may be simulated in the time domain, coupled to any appropriate nonlinear electronics, at a fraction of the cost of a comparable finite-element calculation. The capabilities of the system are demonstrated by the simulation of a feedback-controlled current-sensing system, and the simulation tracks the measured behavior of the system well outside its linear region, to the point that the nonlinear hysteretic core is being driven into and out of saturation, a consequence of a time delay inherent in the electronics. This is compared with a “conventional” electronic simulation of the same system, and the increased accuracy of this technique is clearly demonstrated View full abstract»

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  • Frequency-modulated video recorders: past and present

    Publication Year: 2001 , Page(s): 603 - 604
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    Several misunderstandings about the early history and current design of analog frequency-modulated video recorders appearing in a recent paper are clarified View full abstract»

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  • Head-medium clearance and lateral track registration of a recording head as measured from the readback signal

    Publication Year: 2001 , Page(s): 575 - 582
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Electronic processing of the harmonic content of the readback signal of a magnetic recording device allows the in situ determination of the slider-to-medium mechanical clearance for heads positioned directly over prerecorded tracks and the determination of the lateral displacement variation for heads positioned adjoining to a prerecorded track. In this paper, the theory is derived for such a noninvasive measurement and the required measurement conditions are discussed. The uncertainty in the measurement due to the noise in the readback signal is also presented View full abstract»

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  • Power absorption and ferromagnetic resonance in Co-rich metallic glasses

    Publication Year: 2001 , Page(s): 561 - 564
    Cited by:  Papers (9)
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    The power absorption of Co-rich metallic glasses in the shape of ribbons and microwires has been measured in the microwave frequency range. The technique employed consists of replacing the dielectric of a coaxial transmission line by the amorphous sample to be measured. The ferromagnetic resonance frequency of the microwires has been obtained by analyzing the absorbed power as a function of an external magnetic field. From the evolution of this resonance frequency, the anisotropy field has been deduced and successfully compared to that obtained from low-frequency hysteresis loops View full abstract»

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  • Review of the types, properties, advantages, and latest developments in insulating coatings on nonoriented electrical steels

    Publication Year: 2001 , Page(s): 544 - 557
    Cited by:  Papers (8)
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    Continuous efforts are directed at developing improved electrical steels with lower iron losses for energy-efficient transformers and motors. The core losses can be limited by insulating coatings, and various types of coatings have been developed for application to both fully processed and semiprocessed electrical steels. The primary and secondary properties of such coatings and the inefficacy in ultimately improving machine performance are discussed. This insight is vital to design engineers in making the correct decision on coating requirements. The latest advances made in electrical steel coating technology at European Electrical Steels (EES) are also discussed View full abstract»

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  • Integrals arising in models of shielded magnetoresistive heads

    Publication Year: 2001 , Page(s): 571 - 574
    Cited by:  Papers (1)
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    Integrals arising in two-dimensional models of shielded magnetoresistive heads are expressed either in terms of special functions or as rapidly convergent infinite series. In each case, the form of expression provides an alternative and normally more efficient means of evaluation than direct numerical integration View full abstract»

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  • Accurate analytical model of winding losses in round Litz wire windings

    Publication Year: 2001 , Page(s): 538 - 543
    Cited by:  Papers (41)
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    An accurate analytical model of losses in round Litz wire windings is presented. The model is based on the exact analytical equations for round conductors, and it closely includes the distribution of the leakage field across the winding space. A closed-form formula of the ac resistance of round Litz wire windings is developed from the model. An analytic solution of the optimal value of the ac resistance is derived. The expression of the strand dimension corresponding to the optimal value of the ac resistance is also determined 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