By Topic

Magnetics, IEEE Transactions on

Issue 6 • Date Nov. 2003

Filter Results

Displaying Results 1 - 25 of 29
  • Author index

    Publication Year: 2003 , Page(s): 3622 - 3657
    Save to Project icon | Request Permissions | PDF file iconPDF (520 KB)  
    Freely Available from IEEE
  • Subject index

    Publication Year: 2003 , Page(s): 3658 - 3730
    Save to Project icon | Request Permissions | PDF file iconPDF (843 KB)  
    Freely Available from IEEE
  • IEEE Magnetics Society Distinguished Lecturers for 2004

    Publication Year: 2003 , Page(s): 3475 - 3477
    Save to Project icon | Request Permissions | PDF file iconPDF (205 KB)  
    Freely Available from IEEE
  • Structure, properties, and thermal stability of nanocrystallite Fe-Ti-N soft magnetic films

    Publication Year: 2003 , Page(s): 3554 - 3558
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (341 KB) |  | HTML iconHTML  

    We deposited Fe-Ti-N magnetic films with a high sputtering power of 7 W/cm2. When the composition of the films was in the range of Fe-Ti(3.9 at.%)-N(8.8 at.%) to Fe-Ti(3.3 at.%)-N(13.5 at.%), the films were composed of α' and Ti2N precipitates. With the addition of nitrogen, 4πMs became higher than that of pure iron, reaching a maximum of 23.8 kG. At the same time, Hc was reduced to a minimum of 1.12 Oe. The best films can meet the needs of the recording head in dual-element giant magnetoresistive/inductive heads, yielding high storage density (10 Gb/in2). The incorporation of N in α-Fe brought about the α' phase with its higher saturation magnetization. Ti additions inhibited the equilibrium decomposition α'→α+γ'. Because HCD∝D6, where D is average grain diameter, grain size control is very important. The nitrogen induces severe distortion of the α' lattice, which can cause the grains to break into pieces and reduce the grain size. High sputtering power also led to the formation of fine grains, with diameter in the order of 14 nm. Probably Ti2N is preferentially precipitated on the grain boundary, pinning the grain boundary and stabilizing the grain size during high-temperature heat treatment. The temperature limit for stability of the structure and its associated low coercivity was not less than 520°C. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Preliminary investigation for a cylindrical magnetic storage system

    Publication Year: 2003 , Page(s): 3619 - 3621
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    A cylindrical magnetic storage system was built and preliminary measurements were made. The system is expected to overcome the writing problems at high areal densities caused by write head skew angle and is aimed at the realization of 1 Tb/in2 2 Gb/s perpendicular magnetic recording. Cylindrical substrates, sputtering equipment, and a read/write tester for a cylindrical magnetic storage were fabricated. For this preliminary investigation, the length and diameter of the cylindrical substrates were 1 in. Thin films (protective layer, storage layer, seed layer, etc.) were deposited by rotating the cylindrical substrate during the sputtering process. Fundamental read/write characteristics were measured using an 8 mm video-tape-recorder metal-in-gap head and a merged giant magnetoresistive head with a pico-slider. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fringing in tubular permanent-magnet Machines: part II. Cogging force and its minimization

    Publication Year: 2003 , Page(s): 3517 - 3522
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (507 KB) |  | HTML iconHTML  

    In Part I of the paper, analytical field solutions, which account for the fringing flux associated with the finite length of the ferromagnetic armature core in tubular permanent-magnet machines, are established. In Part II, the technique is applied to both slotless and slotted machines, and the results are verified by finite-element calculations. The analytical field solutions enable the resultant cogging force associated with the finite length of the armature to be determined as a function of the armature displacement, for both radially and Halbach magnetized stators. Thus, they not only provide an effective means for evaluating the influence of leading design parameters on the cogging force waveform, but also facilitate its minimization. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient moment-method solution for the centered shielded magnetoresistive head

    Publication Year: 2003 , Page(s): 3575 - 3580
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    We have solved the field equations for a magnetoresistive shielded head by a Galerkin-type moment method (MM), where the basis functions are chosen to satisfy exactly the edge condition at the head's corners. This choice of the basis expansion functions greatly improves the accuracy and convergence rate of the solution compared to those for MM expansion functions that are not singular. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimizing active and passive magnetic shields in induction heating by a genetic algorithm

    Publication Year: 2003 , Page(s): 3486 - 3496
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (813 KB) |  | HTML iconHTML  

    This paper presents a method for designing optimal passive and active shields for axisymmetric induction heaters. Such shields are needed to protect human operators and external electronic equipment from stray magnetic fields. The method uses a genetic algorithm (GA) to minimize an objective function. This function reduces the magnetic field in the target area, the power dissipation in the active and passive shields, and the influence of the shields on the heating process. The GA returns the position and height of the passive shield, the optimal current for the active shield, and the number of turns of all coils. The paper describes two optimization modes: 1) optimization of only the active shield with fixed passive shield and 2) global optimization of both active and passive shields. Several passive shields are studied: electrically conductive shields and both electrically and magnetically conductive shields. The field reduction depends on the optimization mode and the passive shield properties, but always exceeds 25 dB for combined active and passive shields. Finally, the paper compares the results of the simulations to experimental measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimating rotational iron losses in an induction machine

    Publication Year: 2003 , Page(s): 3527 - 3533
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (497 KB) |  | HTML iconHTML  

    We present an assessment of the effect of rotational losses on an induction machine. The assessment provides an estimate of the iron losses in an induction machine by three methods, all of which rely on the output data of a two-dimensional finite-element method: 1) calculating iron losses as if they were produced by a purely alternating field; 2) calculating the iron losses by adding the losses produced by the orthogonal components of the flux density, as if the losses produced by these components were independent phenomena; 3) applying a correction factor based on experimental data to improve the rotational loss calculation. The correction factor is a function of the peak flux density value and the ratio of the major to the minor axis of the flux density loci. The third method represents the main contribution of this paper to the field and is explained in detail. Finally, a discussion of the results addresses two aspects: the location where rotational fields occur, and their impact on the total loss calculation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use of room-temperature bias sputtering to decrease intergranular coupling in magnetic media deposited on polymeric substrates

    Publication Year: 2003 , Page(s): 3616 - 3618
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB) |  | HTML iconHTML  

    CoCrPt thin films sputter-deposited on polymeric substrates without explicit heating were investigated as a function of substrate bias. The coercivity and the coercive squareness in the CoCrPt films were strongly dependent on bias voltage. A significant reduction in the coercive squareness S* from a value near unity was observed with increasing bias voltage, implying a decrease in the degree of intergranular exchange coupling. With the addition of explicit substrate heating, S* was further reduced, and was associated with a significant improvement of coercivity. This paper presents a possible approach to achieve media with acceptably low exchange coupling deposited at temperatures well below the glass transition temperature of polymeric substrates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of a 0.3-Tb/in2 low-power MFM-based scanning-probe device

    Publication Year: 2003 , Page(s): 3566 - 3574
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (909 KB) |  | HTML iconHTML  

    In this paper, we present an analysis of the performance of a 0.3-Tb/in2 ultralow-power magnetic-force-microscopy-based scanning-probe storage device actuated by microelectromechanical systems technology. The device is currently under development at Carnegie Mellon University, Pittsburgh, PA. The analysis shows that, with an optimized commercial single-layered Co-based perpendicular medium with an optimized tip trajectory, a signal-to-noise ratio of 20-25 dB is achievable. The analysis includes general design considerations as well as various aspects of performance such as recording dynamics, PW50, intersymbol-interference limit, detection sensitivity, thermal degradation, intertrack interference, off-track errors, process variations, and surface fluctuation effect. Design/performance standards for the new device are suggested. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimum design of magnet shape in permanent-magnet synchronous motors

    Publication Year: 2003 , Page(s): 3523 - 3526
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB) |  | HTML iconHTML  

    In order to improve the efficiency of the permanent-magnet synchronous motor, which is closely related to its magnet shape, we have designed magnets in various shapes. A parallel top sine wave design has proved to be an optimum plan. This design adds three time components of induced phase voltage, which enables the amplitude of induced line voltage to increase about 14.9%. The design's simplified approximate arc configuration has important engineering applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Time-domain modeling from S parameters: applicable to hard disk drives

    Publication Year: 2003 , Page(s): 3581 - 3586
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    Network parameters characterize a network or device, allow one to mathematically insert it into a system, and enable one to calculate or predict system performance. The S parameters may be the most widely measured such parameters; they are readily applied to compute network-port voltages and currents in the frequency domain. However, it is sometimes preferable to compute the voltages and currents in the time domain; for example, when a network-terminating device is nonlinear. This paper provides and demonstrates a numerical method for converting S parameters to time-domain models that can be readily evaluated with ordinary differential equation solvers. No inverse fast Fourier transform or convolution integrals need to be evaluated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Recording by an ideal single-pole head onto an array of Stoner-Wohlfarth magnetic particles

    Publication Year: 2003 , Page(s): 3563 - 3565
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB) |  | HTML iconHTML  

    This paper presents a theory of recording by a probe head onto an array of individual magnetic particles. The theory predicts the area packing density of particles and shows that head-to-medium spacing is the prime factor in determining its value. The paper investigates the trade between attainable packing densities and variations in medium properties. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental characterization of on-chip inductor and capacitor interconnect: part I. Series case

    Publication Year: 2003 , Page(s): 3497 - 3502
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (570 KB) |  | HTML iconHTML  

    Detailed experimental investigations described here show the overall characteristics of on-chip inductor and capacitor serial interconnects (L--Cs) on silicon substrates. Using a new equivalent circuit model and the measured S parameters obtained by deembedding techniques, we examine and compare a single inductor, single capacitor, and two sets of series L--Cs. Agreement between the measured and simulated S parameters is excellent. At low frequency, the first resonant frequency fres of series L--Cs can be easily determined by fres=(2π√(LC))-1, while at high frequency, parasitic parameter effects of both the substrate and the metal strips on fres of the L--Cs circuit must be considered. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New kind of NdFeB magnet prepared by spark plasma sintering

    Publication Year: 2003 , Page(s): 3551 - 3553
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (527 KB) |  | HTML iconHTML  

    We have produced an anisotropic Nd15.5Dy1.0Fe72.7Co3.0B6.8Al1.0 magnet by the spark plasma sintering (SPS) technique and compared it with a magnet of the same composition processed by the conventional sintering method. We investigated magnetic properties, microstructure, and constituents by a B-H loop-line instrument, a scanning electron microscope, and an energy-dispersive X-ray detector, and studied the effects of processing conditions on the magnetic properties, dimensional precision, and density. We also examined the magnet's electrochemical properties in electrolytes and its corrosion behavior in oxidizing environments. We found that the microstructure of the SPS NdFeB magnet is different from that of the conventional one. In the SPS-processed magnet, the grain size is fine and uniform while the distribution of the Nd-rich phase is heterogeneous. The SPS NdFeB magnet has a maximum energy product of 240 kJ/m3 and a coercive force of 1260 kA/m. The density of the magnet reaches 7.58 g/cm3, and its dimensional precision is about 20 μm. The electrochemical properties and the corrosion resistance of the SPS NdFeB magnet are better than those of the conventional one. The SPS process is a promising method for the production of NdFeB magnets with ideal overall performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic force control with composite of giant magnetostrictive and piezoelectric materials

    Publication Year: 2003 , Page(s): 3534 - 3540
    Cited by:  Papers (13)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (801 KB) |  | HTML iconHTML  

    We propose a new magnetic force control device, composed of a giant magnetostrictive material (Terfenol-D) and a piezoelectric material (PZT), for coilless magnetic force control. The device uses the inverse magnetostrictive effect, whereby the variation of magnetization of a Terfenol-D rod controlled by PZT is converted to the variation of magnetic force by a magnetic circuit. Because PZT is electrically capacitive, the method has the advantage of low power consumption and low heat generation in static operation. We have fabricated several devices with different geometrical shapes of the rods and magnetic yokes, and we describe their characteristics such as power consumption, heat generation, and response. We discuss a magnetic circuit design strategy that uses the ΔE effect in magnetostrictive materials to increase the energy conversion efficiency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Processing of magnetic properties of nearly zero magnetostrictive glass-coated microwires by current annealing

    Publication Year: 2003 , Page(s): 3613 - 3615
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB) |  | HTML iconHTML  

    The effect of dc current annealing (with length up to 80 min and current density j up to 250 A/mm2), with or without dc axial magnetic field, on the magnetic properties of Co55.7Fe5.9Ni9.9B17.7Si10.8 and Co68Mn7Si10B15 glass-coated microwires has been studied. Such thermal treatments, especially performed under magnetic field, modify the magnetic parameters, such as coercivity, remanent magnetization, magnetic permeability, and overall shape of the hysteresis loops. Such phenomenology can be interpreted by considering the noticeable longitudinal magnetic anisotropy induced by the combined effects of the magnetic field and internal stresses arising from the coating during the thermal treatment. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synchronous servo scheme using maximum-likelihood detectors

    Publication Year: 2003 , Page(s): 3593 - 3603
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (666 KB) |  | HTML iconHTML  

    For magnetic disk drives, we have developed a scheme for synchronous servo with maximum-likelihood (SSML) detection that is synchronous around the entire circumference of the track and utilizes ML estimation to detect head position, clock mark phase, and track addresses. Compared to the conventional asynchronous sector servo scheme, the SSML scheme has many, much shorter, servo areas-typically several hundred-distributed on the disk. This results in higher servo information rate, which will be needed for future high-track-density disk drives with a wide servo bandwidth. We analyze the performance of the SSML scheme, including the format efficiency. We discuss a limitation of the synchronous servo scheme with respect to the number of servo areas, and we show an appropriate region for its application. Feasibility of the SSML scheme has been demonstrated in prototype 2.5-in hard disk drives. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sputtered FeCoN soft magnetic thin films with high resistivity

    Publication Year: 2003 , Page(s): 3559 - 3562
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    Fe70Co30N thin films with thickness from 20 to 1100 Å were prepared by radio- frequency reactive sputtering in an N2--Ar mixture. The FeCoN films prepared in a low nitrogen flow rate percentage (<6%) and sputtering pressure (<8 mTorr) have a high Bs of about 24.0 kG, but a moderate hard-axis coercivity Hch of 5-30 Oe. With further increase in N2 percentage or sputtering pressure, films become significantly softer, with Hch of about 0.1-0.6 Oe, and have a higher resistivity of up to about 160 μΩ·cm. The change in the magnetic properties with nitrogen flow rate percentage and sputtering pressure can be attributed to the formation of an ultrafine grain size nanocrystalline FeCoN thin film as observed by high-resolution transmission electron microscope. The soft properties of FeCoN films with nano-sized crystallites remain stable even after being annealed at 270°C. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast multipole method for micromagnetic simulation of periodic systems

    Publication Year: 2003 , Page(s): 3478 - 3480
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    We have developed a new method for computing the magnetostatic field of an infinite array of images of an arbitrary system of charges or multipoles. The result takes the form of a Taylor expansion of the potential of a "cored array" of distant images, as is required by the fast multipole method, the most efficient method known for calculating magnetostatic fields in very large systems. The new method is much faster and simpler to implement than the usual Ewald summation or fast Fourier transform, and does not require a regular grid inside the central cell. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic micro-actuators and systems (MAGMAS)

    Publication Year: 2003 , Page(s): 3607 - 3612
    Cited by:  Papers (102)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    Magnetic interactions provide outstanding performances for powerful integrated micro-actuators. This paper explains how magnetic interactions involving permanent magnets, currents, and various magnetic materials remain very effective and even improve as dimensions are reduced. The technological problems that have slowed the development of magnetic micro-actuators and systems (MAGMAS) are progressively being solved. As long as materials scientists continue to develop better thick-film patterned permanent magnets compatible with microsystem technologies, MAGMAS will have a promising future. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modified dual-stage controller for dealing with secondary-stage actuator saturation

    Publication Year: 2003 , Page(s): 3587 - 3592
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (426 KB) |  | HTML iconHTML  

    This paper proposes a modified decoupled master-slave (DMS) dual-stage control scheme for hard disk drives that offers enhanced stability when the secondary-stage actuator is saturated. A nonlinear secondary-stage actuator model is used instead of a linear model in the controller. This modification allows microactuators with relatively smaller displacement range to be used in the servo system without causing stability problems in the DMS controller. Simulation and experimental results confirm the effectiveness and robustness of the scheme. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Tilted toroidal coils for superconducting magnetic energy storage systems

    Publication Year: 2003 , Page(s): 3546 - 3550
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (550 KB) |  | HTML iconHTML  

    Superconducting magnetic energy storage (SMES) systems can be used to improve power supply quality and reliability. In addition, large amounts of power can be drawn from a small stored energy supply. Nevertheless, the strong electromagnetic force caused by high magnetic fields and coil current is a serious problem for SMES. To cope with this problem, we propose a new coil design, the tilted toroidal coil (TTC). The TTC, obtained from the toroidal field coil (TFC) system by varying two pitching angles, allows the balancing of the electromagnetic force in the major radius direction, maintaining the same manufacturing simplicity of the TFC system. After determining balanced configurations through computer simulation, we built an experimental device to confirm the feasibility of the balancing effect. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sensitivity analysis of simulations for magnetic particle inspection using the finite-element method

    Publication Year: 2003 , Page(s): 3604 - 3606
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    Magnetic particle inspection (MPI) is widely used for nondestructive evaluation in aerospace applications in which interpretation of inspection results is currently limited to empirical knowledge and experience-based approaches. Advances in computational magnetics, particularly the use of finite-element calculations, have enabled realistic numerical simulations of magnetic particle inspection to be undertaken with complicated geometries. In this paper, we report a sensitivity analysis using finite-element-method simulations of magnetic particle inspection for defects with various sizes and geometries. As a result, improved quantitative understanding of the MPI technique and factors that affects its sensitivity and reliability has been achieved. These results can be used to optimize conditions for conducting these inspections and should lead to improvement in analysis and interpretation of experimental results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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.

Full Aims & Scope

Meet Our Editors

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