By Topic

Magnetics, IEEE Transactions on

Issue 4 • Date July 1980

Filter Results

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

    Publication Year: 1980 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (186 KB)  
    Freely Available from IEEE
  • Effects of annealing on propagation in ion-implanted contiguous-disk bubble devices

    Publication Year: 1980 , Page(s): 553 - 557
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB)  

    Bubble propagation margins are found to be affected by heat treatment in ion-implanted contiguous-disk devices fabricated on liquid-phase epitaxial (LPE) grown double-layer garnet films which support 1-μm bubbles. When an optical reflector is deposited directly on the driving layer interfacial diffusion takes place, and this raises the coercivity of the implanted layer, which in turn causes a severe degradation of propagation margins. In samples fabricated with optical reflectors isolated from the driving layer, the adverse effects of annealing on propagation margins are stronger in close-packed minor loops due to interaction of long-range charged walls as compared with isolated loops and isolated disks, and they cease to propagate bubbles after annealing in the temperature range of 350-400°C, whereas the loss of margins in the isolated loops and disks are typically less than 30 percent after 600-650°C annealing treatments. Stress gradients caused by the discontinuity in the overlay patterns contribute significantly to the increase of threshold drive field after anealing. The rapid degradation of propagation margins found after annealing in the temperature range of 350-400°C in all samples is caused by reordering of the damaged lattice. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Aging of magnetic recording tape

    Publication Year: 1980 , Page(s): 558 - 568
    Cited by:  Papers (6)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1072 KB)  

    Almost all commercial magnetic recording tapes are manufactured employing a polyester urethane elastomer as the oxide binder and also as the backcoat binder on backcoated tapes. For temperature excursions encountered for ordinary tape use and storage, polyester urethanes as a general class of materials are typically susceptible to environmental degradation by hydrolysis: a chemical reaction between these materials and atmospheric water vapor. Extensive hydrolytic degradation can lead to the generation of sticky and gummy chemical products. It can be anticipated that a substantial contribution to environmental tape aging and performance characteristics might derive from the chemical behavior of ester hydrolysis. The environmental aging of a commercial magnetic recording tape was experimentally investigated, and it was found that the primary mechanism of tape aging and degradation resulted from hydrolysis of its polyester urethane binder. The chemical reaction is additionally reversible, a property which suggests a methodology for restoring and rejuvenating environmentally degraded tapes. Being a reversible reaction, there exists environmental conditions of relative humidity and temperatures which are ideal for long-term archival preservation. For the tape of this study, 24-percent relative humidity (RH) at room temperature was identified as its ideal storage humidity. This study may have significance for many industrial and government specifications which call out assorted qualifying tests involving tape exposure or tape operations at extremes of humidity and temperature. It is suggested from the findings of this work that such tests may measure and monitor the various manifestations of hydrolysis, which may bear little if any relationship to tape use at moderate ambient conditions or in hermetic environments. The results of this work further indicate that hermetic sealing of a tape may allow operations to higher temperatures than possible in air, with the upper temperature limit determined by lubricant boil-out or thermal degradation (pyrolysis) of the polymers. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An approach estimating the number of domain walls and eddy current losses in grain-oriented 3% Si-Fe tape wound cores

    Publication Year: 1980 , Page(s): 569 - 572
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    A method is presented for estimating the number of domain walls in grain-oriented 3% Si-Fe tape wound cores under sinusoidal flux conditions by extending the method developed in a study of the dynamic behavior of 50% Ni-Fe square-loop cores. The results show that the number of domain walls increases approximately with exciting frequency as f^{0.4 \sim 0.5} . The calculated eddy current loss based on the modified Pry and Bean equation and the obtained number of domain walls agree well with the measured loss. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Preparation and properties of Fe-B-Si-C amorphous alloys

    Publication Year: 1980 , Page(s): 572 - 574
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    The crystallization temperatures, magnetic properties, and density of amorphous alloys of FexBySizCzare reported for 72 < x < 88, 16 < y < 28 , and 0 < 2z < 12 . The peak value of 4 ± Msis 17 kG in the as-cast state and occurs in the region of Fe82B13Si2.5C2.5. The crystallization temperatures, Curie temperatures, saturation magnetization, and density all appear to be average values of the ternary Fe-B-Si and Fe-B-C properties. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effect of shaking on magnetic shields

    Publication Year: 1980 , Page(s): 575 - 578
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    The increase of the shielding factor due to shaking was measured in a scale model for a magnetically shielded room. The increase was found to be 7 dB for a single-layer square cylinder biased by the Earth's magnetic field. The shielding factor of a large-volume three-layer Mumetal®room was estimated to increase by a factor of 30, thus confirming the feasibility of shaking in magnetic shields. The shaking parameters, amplitude, and frequency are not critical according to the experiments. Winding the shaking coils along the edges of the cubic shield leads to minimum disturbances inside the cube, and the winding can also be applied to demagnetize the shield by an alternating field of 25 A/m, 50 Hz. The relative incremental permeability of Mumetal was studied as a function of the shaking and biasing fields. The permeability was found to increase considerably by shaking and by decreasing the biasing field. With zero biasing and with shaking field of Hs= 5 A/m root mean square (rms), 50 Hz, the permeability reached its maximum value of 89 000, which is sevenfold the value without shaking. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The magnetic field problem: A graph-theoretic model

    Publication Year: 1980 , Page(s): 579 - 585
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    A numerical model for two-dimensional magnetic field problems called the graph-theoretic field model is presented. The theoretical framework of the model places the finite difference and Finite element method in a unifying perspective and brings the solution of magnetic field problems into the well-proven realm of computer-aided design of discrete physical systems. The field distribution in a transformer core is obtained to illustrate the modeling procedure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Processing a conventional magnetic bubble circuit with a 6-µm period

    Publication Year: 1980 , Page(s): 586 - 587
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A conventional magnetic bubble memory with a 6-μm period and submicron details has been made. The memory is an 8-kbit shift register single-mask design with field access NiFe propagation elements. The transfer gates and detector area have an 8-μm period, while the major part of the storage loop has an enhanced density with a 6-μm period. The processing is done with a 1:1 electron image projector, which is capable of making the 0.75-μm smallest features necessary for this circuit. The fabrication uses a lift-off technology with Ti followed by a reactive sputter-etch procedure for the structuring of the NiFe elements. View full abstract»

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

    Publication Year: 1980 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (288 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