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Magnetics, IEEE Transactions on

Issue 1 • Date March 1965

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Displaying Results 1 - 19 of 19
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Frontispiece

    Page(s): 2
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    First Page of the Article
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  • Message from the chairman

    Page(s): 3 - 4
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    Freely Available from IEEE
  • Administrative committee

    Page(s): 5 - 9
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    Freely Available from IEEE
  • A coupling phenomenon between the magnetization of two ferromagnetic thin films separated by a thin metallic film--Application to magnetic memories

    Page(s): 10 - 12
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    A new type of magnetic interaction between two ferromagnetic thin films separated by a third metallic nonmagnetic thin film is studied. This coupling tends to bring the magnetization of the ferromagnetic materials into parallel alignment. The coupling is shown to be dependent upon the intermediate material and its thickness, and on the nature of the ferromagnetic media present. These interactions are observed for intermediate metal thicknesses up to 300 Å in the case of Palladium. The measured surface energy of this coupling is of the order of 0.1 erg/cm2. A study of the variation of the coupling with temperature is given. View full abstract»

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  • Woven thin-film wire memories

    Page(s): 13 - 17
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    Extraordinary advances in electronic computers can be expected with the development of newer types of quick-access memories. Much research is being carried out, at present, on the use of magnetic thin-films for magnetic memories. Since many elements must be employed, it is desirable that each bit be absolutely reliable, simple, inexpensive, and suitable for mass production. Through basic experiments, the authors have confirmed the possibility of utilizing a fine diameter wire whose surface has been continuously coated or electroplated with a ferromagnetic thin-film for high-speed memories. Sample woven-type memory matrices, 50 by 50 bits, 64 by 100 bits, and 100 by 100 bits, were constructed using 0.2-mm diameter coated wires for digit and sense circuit operation, and 0.07-mm insulated wires for the drive circuit operation. Tests on the relation between the writing, the drive pulse currents, and the output voltages revealed many superior features not found heretofore in other types of thin-film memories. Means are being devised for the weaving methods and for the elimination of mutual interference between adjacent bits. This paper also discusses the characteristics of the coated wire and the performance of samples constructed for practical use. View full abstract»

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  • A high-speed card changeable permanent magnet memory--The inverted twistor

    Page(s): 18 - 21
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    A high-speed card changeable permanent magnet twistor memory is described. High switching speeds at low drive current levels are obtained by inverting the twistor (using the twistor wire as the word line rather than the sense line as in previous designs). A 512-word, 24-bit memory having a cycle time capability of 250 ns has been constructed and evaluated. Bipolar drive currents of 600 mA produced switching times of 60 to 70 ns and signal levels of 12 to 16 mV. The characteristics of a 4096-word, 90-bit memory are predicted. Drive currents of 400 mA would produce outputs of 10 mV and a cycle time of less than 400 us. View full abstract»

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  • System and fabrication techniques for a solid-state random-access mass memory

    Page(s): 21 - 25
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    This paper describes a development program aimed at improving processing speeds by providing data processing systems with random-access memories approaching the speed of ferrite-core matrix memories, but at a cost that economically permits of mass-memory capacities. Compatible system and fabrication techniques were devised to reach the low cost objective. The paper details the system and fabrication techniques, and in addition to demonstrating low memory cost, describes small power, weight, and size characteristics that might be important in special applications. View full abstract»

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  • Magnetic film phase-locked oscillator

    Page(s): 26 - 30
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    The Phase-Locked Oscillator (PLO), also known as a parametron, was proposed almost simultaneously in 1954 by Von Neuman and Goto as a digital device [1], [2]. Since that time, much developmental of effort has been placed on parametrons utilizing ferrite cores and magnetic films. A comprehensive presentation of the use and application of the PLO can be found in the technical literature [3]-[8]. This paper is concerned with the mathematical analysis of the magnetic film PLO which is described by a nonlinear Mathieu equation. Although there are many analyses of the PLO, they all fall short of yielding a closed-form solution which quantitatively and explicitly relates circuit and film parameters to actual operation [2],[3],[7]-[12]. By establishing such a relationship, solutions for the transient response with limiting characteristics, operating frequency, and steady-state operation have been obtained. View full abstract»

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  • Two-phase, all-magnetic shift registers that can be operated with a single pulse driver in the 0 to 5 KC range

    Page(s): 31 - 35
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    Two-phase, all-magnetic shift registers have been designed and operated using either two pulse drivers or a single pulse driver and a dc source. The theory of operation of a one-core-per-bit register and a two-core-per-bit register is presented. Experimental information is given that demonstrates the significant operating characteristics of the circuits. View full abstract»

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  • Silicon gate-controlled AC switch and its applications

    Page(s): 36 - 42
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    A new silicon switch, called Triac, having three terminals and able to control alternating current, is described. It is an avalanche device controlling load current flow in both directions in response to a gate signal. Some of the properties of the Triac are described, and circuits such as on-off and gradual controls are shown for its control. Applications for the Triac include the control of electric heaters, and of incandescent and fluorescent lights. View full abstract»

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  • High-frequency time-ratio control with insulated and isolated inputs

    Page(s): 43 - 48
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    Fast-responding amplifiers are needed in many industrial and defense systems. Systems using power amplifiers with one to 1000 watts of output dc power require high performance. The requirements often include high efficiency, light weight, compactness, high reliability, economy, and simplicity, along with fast response and insulated multiple inputs. These performances are required in applications such as controls for high-power inverters and converters, motors, generators, light, heat, dc-to-ac inverters, power supplies, servo systems, etc. This paper presents a transistor-magnetic power amplifier with multiple insulated and isolated inputs (Fig. 1) with characteristics in Fig. 2. The technique of time-ratio control [1] is used to provide light weight, compactness, high efficiency, and high reliability. High-speed power transistors (0.1 μs) combined with a tunnel diode circuit permit high chopping frequency (50 kc). The base current of the power transistor is switched in-less than 0.02 μs. Insulated and isolated inputs are provided by a small saturable transformer the size of a TO-5 transistor case. Transistor inputs are used on the saturable transformer. Germanium power transistors (such as 2N1907) are used to provide economy, but silicon transistors can be used for applications at high ambient temperature. The circuit of Fig. 1 is used to fire controlled rectifiers for inverters and converters. A pulse transformer in series with a resistor replaces the load of Fig. 1 when needed in firing circuits. A simple time-ratio control (TRC) circuit is presented that controls the output [Fig. 2(a)] by varying the chopping frequency from 50 kc to 5 kc. The multiple inputs are illustrated. A constant frequency (50 kc) TRC is presented that controls load voltage from zero to the supply voltage [Fig. 2(b)]. The output responds to the control signal in 40 μs. The tunnel diode switching circuit is also presented. View full abstract»

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  • Stabilized 400 to 3600 c/s magnetic frequency multiplier

    Page(s): 49 - 53
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    This paper presents detailed design information and performance characteristics of a stabilized 400 to 3600 c/s frequency transformer of the phase multiplier type. The described three-phase-operated prototype design provides a maximum output power of 40 watts. The performance is such that, with output power values up to about 20 watts, actual variations of the 3600 c/s output voltage are ±0.1 to 0.3 percent, although the 400 c/s supply voltage may be changed within the wide range of 80 to 220 volts. As a result of the application of square-loop core material (Orthonol 2-mil tape cores), the waveform of the square-wave output voltage is similar to that of a switching transistor magnetic core multivibrator. Since the output terminals can be permanently short-circuited, the frequency multiplier protects itself and the equipment it supplies from overloads. In view of these properties, the described prototype design will be valuable for those applications in control engineering, where simplicity, ruggedness, extreme reliability, and almost unlimited life, are of prime importance. View full abstract»

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  • Power transfers in nonlinear frequency converters with three commensurable frequencies

    Page(s): 53 - 56
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    For systems with three arbitrarily assigned commensurable frequencies and nonlinear coupling approximated by a truncated power series, the possibility of power transfers depends on the exponents of the polynomial describing the nonlinearity. The applicability of power-frequency relations, which is uncertain when the frequencies are commensurable, also depends on the form of the polynomial. Pertinent criteria and examples are given. View full abstract»

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  • A new type magnetic modulator

    Page(s): 56 - 62
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    A one-core magnetic modulator based on a new principle is described which operates as a high-sensitivity small-input dc-ac converter with a drift or noise level of the order of 10-16watts. The residual output in response to an excess input can be kept below about 10-μA turns in terms of equivalent input. In the case of push-pull connections, the characteristics are greatly improved, under far more loose conditions than with conventional second-harmonic-type modulator. View full abstract»

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  • Magnetic properties of multilayer films of FeNi-Mn-FeNiCo and of FeNi-Mn

    Page(s): 63 - 65
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    Experiments made on multilayer evaporated thin films with a structure FeNi-Mn-FeNiCo and FeNi-Mn exhibit strong evidence of a ferromagnetic-antiferromagnetic exchange coupling between the ferromagnetic film of FeNi and a transition layer at the FeNi-Mn interface obtained by mutual diffusion of Mn and FeNi at 300°C. The surface coupling energies measured may be as much as 0.3 erg/cm2. View full abstract»

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  • Anisotrophy control of Ni-Fe films through sequenced-field deposition

    Page(s): 66 - 67
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    Anisotropy of nickel-iron films of 82, 74, and 66 per cent nickel compositions was controlled by time-sequenced application of orthogonal fields during deposition. Resulting anisotropy values are in agreement with simpleM-induced anisotropy principles. Coercive forces show small but definite decrease with anisotropy constant. Dispersion angle is proportional to the reciprocal of the anisotropy constant. The technique is suitable for production of low-Hkfilms. It permits nonanomalous inverted films to be produced and allows the study of other anisotropy sources. View full abstract»

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  • Design of a fully associative cryogenic data processor

    Page(s): 68 - 71
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    The following material has detailed the computational algorithms and basic cryotron circuits necessary to provide fully associative search operation and flexible data handling characteristics in a fully associative cryogenic data processor. Although a detailed description of total processor system design is beyond the scope of this text, its major characteristics have been treated. A newly developed fabrication technique makes practical the fabrication of high-density, structurally stable cryotron circuits for such a data processor. View full abstract»

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  • [Back cover]

    Page(s): 0
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    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.

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Meet Our Editors

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