By Topic

Magnetics, IEEE Transactions on

Issue 6 • Date November 1977

Filter Results

Displaying Results 1 - 9 of 9
  • [Front cover and table of contents]

    Publication Year: 1977 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (175 KB)  
    Freely Available from IEEE
  • Grain-size effects on microwave ferrite magnetic properties

    Publication Year: 1977 , Page(s): 1729 - 1744
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1824 KB)  

    This paper presents a review of polycrystalline microwave ferrites with specific reference made to the grain size. Fine-grained ferrites and large-grained ferrites as referred to in this article stand for the ferrites with an average grain size of 2 μm or less and those of 100 μm or larger, respectively. Fine-graining of ferrites is one of the state-of-the-arts techniques for obtaining high-power ferrites. Large-graining is a newly developed technique for further improving the family of narrow resonance linewidth garnet materials. Starting with some ceramics-oriented topics including the definition of the average grain-size and so forth, the present review covers the grain-size dependence of initial permeability and the grain-size dependence of microwave properties (ΔH, ΔHeff, and ΔHk) both in the theoretical and in the experimental phases. Successful device applications of newly developed "single-crystal-like" large-grained ferrites are also reviewed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Contiguous-disk bubble domain devices

    Publication Year: 1977 , Page(s): 1744 - 1764
    Cited by:  Papers (16)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2840 KB)  

    Contiguous-disk bubble devices are an approach to higher bit density through the use of coarse overlay patterns in manipulating small bubbles to relax device lithography requirements. As a first step towards such an objective, a fully processed chip using ion-implanted devices has been tested, showing the feasibility of all required memory functions with 5-μm bubbles and 25-μm period overlay patterns. A critique of permalloy versus implanted contiguous-disk devices is made, pointing out their basic difference in magnetization reversal processes and explaining the superiority of the latter over the former in achieving a good edge affinity of bubbles. The requirements for a good implanted device are reviewed, including the selection of garnet material parameters (K1, λ111), of implantation parameters (ion energy and dosage) and of device pattern geometry (thickness and shape of implanted layer). An understanding of these requirements has made it possible to demonstrate 1-μm bubble propagation in several contiguous-disk type circuits with 4.5-μm periods, yielding an areal density of over 3 × 107bit/in2made by conventional photolithography. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analytical expressions for side fringing response and crosstalk with finite head and track widths

    Publication Year: 1977 , Page(s): 1764 - 1766
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    An analytical expression is derived that describes the response of a magnetic read head of finite width to a magnetized track of finite width shifted in the lateral direction. With this expression the side fringing response and crosstalk from adjacent tracks are calculated and a number of results is presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Temperature dependence of the magnetic properties of amorphous Co-Gd-Mo thin films

    Publication Year: 1977 , Page(s): 1767 - 1772
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    RF sputter deposited amorphous Co-Gd-Mo thin films have previously been shown to be potential materials for bubble device applications. However, the operation of a bubble device over a realistic temperature range requires materials with magnetic properties which are relatively temperature insensitive. An assessment of the temperature dependence of the magnetic properties of amorphous Co-Gd-Mo films is reported. The results of a mean field analysis of the magnetization data of Co-Gd-Mo thin films over wide composition and temperature ranges allowed optimization of the film composition for obtaining most suitable temperature dependences of magnetic properties. It has been found that even with the optimum compositions, the degree of temperature insensitivity improves with decreasing bubble diameters and is satisfactory only for sub-half-micron bubble materials. These results and analysis suggest that similar qualitative behavior may also be expected for other transition metal-rare earth alloys. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Chevron detector design study

    Publication Year: 1977 , Page(s): 1773 - 1776
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    Results obtained in a design study which has attempted to optimize the detector chevron and interconneetion geometry are reported. The detector waveform with interconnections between chevrons placed at alternating ends of the chevrons is redundant, with the second half cycle largely repetitious of the first as the domain traverses the detector. The present designs attempt to select the first half cycle by placing the second set of interconnections asymmetrically, near the center of the chevron column. The selected signals are then enhanced by narrowing the chevron linewidth on the incoming side where the serpentine current path is defined. Detector waveforms obtained with such designs have a high resistance state, when a bubble is present, which peaks just before a rapid change into a low resistance state such that the maximum excursion can be used with conventional clamp and strobe sense amplifiers. The dependence of the output on linewidth, garnet thickness, and static in-plane offset field are investigated experimentally. Detector figures of merit, i.e., signal voltage divided by dc voltage, of 0.5% have been observed and appear robe obtainable in a practical sense. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Induction heating for case hardening applications

    Publication Year: 1977 , Page(s): 1776 - 1785
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    It is observed that the equations describing induction heating in ferromagnetic materials are rather nonlinear. Although the thermal properties are nonlinear, the greatest nonlinearity arises from the ferromagnetic behavior of the material. A way of circumventing this difficulty while retaining the important magnetization curve is presented. A numerical solution accounting for temperature variations in the saturation magnetization, electrical and thermal conductivities, and specific heat is presented. It is found for case hardening applications that only a narrow near surface region heats to the vicinity of the Curie temperature, and a simple theory describing this region is derived. Just beyond the near surface region a sharp temperature gradient results which is of importance in case hardening. A simple expression for the gradient is developed. These expressions, verified by a complete numerical analysis, aid in the choice of an induction heating excitation system for case hardening applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A true swap gate for magnetic bubble memory chips

    Publication Year: 1977 , Page(s): 1785
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    The design of a true swap gate suitable for incorporation into magnetic bubble memory chips with 16-μm to 18-μm circuit periods is reported. The swap operation is true in that the outcoming bubble takes the position vacated by the ingoing bubble, as well as vice versa. Swap gates of this design have been operated successfully at temperatures from 0°C to 70°C, and frequencies up to 100 kHz. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Publication Year: 1977 , Page(s): 0
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | PDF file iconPDF (4562 KB)  
    Freely Available from IEEE

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