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Magnetics, IEEE Transactions on

Issue 1 • Date March 1968

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Displaying Results 1 - 22 of 22
  • [Front cover and table of contents]

    Publication Year: 1968 , Page(s): 0
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    Freely Available from IEEE
  • Editorial

    Publication Year: 1968 , Page(s): 2
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    First Page of the Article
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  • Biography of the third ICMF

    Publication Year: 1968 , Page(s): 3 - 5
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    Provides a histoey of the events leading to the Third International Colloquium on Magnetic Films (Boston, Massachusetts, 18-20 September 1967). View full abstract»

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  • Saturation magnetization in ferromagnetic thin films

    Publication Year: 1968 , Page(s): 6 - 11
    Cited by:  Papers (3)
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    The present status of the theory of saturation magnetization of ferromagnetic thin films is reviewed. The extensions of the Heisenberg trace method and the spin-wave method to the case of ferromagnetic thin films is fully discussed together with a comparison of the theoretical results with experimental data. The effect of anisotropic magnetic fields on magnetization and Curie temperature is presented, and the dependence of the magnetization and Curie temperature on film thickness is studied. Very recent progress and new results of the theory are stressed. The application of the Green function method to ferromagnetic thin films is also examined. View full abstract»

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  • Superparamagnetic effects in thin films

    Publication Year: 1968 , Page(s): 11 - 14
    Cited by:  Papers (1)
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    The experimental and theoretical concept concerning the magnetic properties of 2-dimensional arrangements of small particles with different strengths of interaction is discussed. Taking into account recent results on isolated small single-domain particles, a representation for a whole scale of possible structures from these to closely packed ferromagnetic films is given, using a molecular field formalism. The interaction considered may be much weaker than the full ferromagnetic exchange coupling. The resultant collective magnetization M of such aggregates of small particles may be considerably lower than their spontaneous magnetization Ms. A transition temperature TAtowards occurrence of superparamag-netism may appear that is well below the Curie temperature Θ of the individual particles. These effects seem to be consistent with experimental data obtained by a number of authors using various methods of measurement. Observations of time effects at magnetization reversals in very thin films also support the aforementioned model. View full abstract»

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  • Induced anisotropy in Ni-Fe films

    Publication Year: 1968 , Page(s): 15 - 19
    Cited by:  Papers (9)
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    A survey of experimental results for magnetic anisotropy induced during evaporation and annealing of polycrystalline Ni-Fe alloy films is given. Existing data for the uniaxial anisotropy constant K appear to be bounded from above by the combined predictions of strain and directional-ordering theories. The strain anisotropy frequently attains theoretical values, and often less, while directional-ordering anisotropy in high-vacuum films (circa 10-5torr) generally attains half or less of theoretical expectations. View full abstract»

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  • Electrodeposited films

    Publication Year: 1968 , Page(s): 19 - 21
    Cited by:  Papers (4)
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    This investigation covers: a) control of characteristics of electrodeposited vs. vacuum deposited Permalloy films; b) the preparation of substrates for electrodeposition; c) aging kinetics of electrodeposited NiFeSxfilms from 60° to 90°C; and d) comparison of aging of NiFeSxfilms with electrodeposited films containing other impurities, e.g., NiFeP, and with films made by other techniques, e.g., vacuum deposition. The concluding discussion is principally concerned with aging effects. View full abstract»

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  • Perpendicular anisotropy of evaporated magnetic films

    Publication Year: 1968 , Page(s): 22 - 25
    Cited by:  Papers (4)
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    Evidence of the existence of origins of perpendicular anisotropy other than the ordinary magnetostrictive effect is presented with a brief review of other studies. As one of these origins, the effect of the grain boundaries or the microscopic shape effect is discussed. The amount of perpendicular anisotropy observed in the stripped films does not seem capable of explanation by this effect only. View full abstract»

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  • Coupling in multilayered magnetic films

    Publication Year: 1968 , Page(s): 26 - 28
    Cited by:  Papers (2)  |  Patents (1)
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    A coupling between the magnetization of two ferromagnetic films separated by a thin metallic layer has been observed. It is shown that when the intermediate layer is palladium the coupling results from diffusion of magnetic atoms into the palladium which makes it weakly ferromagnetic. The main systems in which ferro-antiferromagnetic coupling is observed are Co-CoO, Ni-NiO, FeNi-FeNiMn. In the latter case domain patterns and ripple are observed by electron microscopy. View full abstract»

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  • Spin-wave resonance

    Publication Year: 1968 , Page(s): 28 - 31
    Cited by:  Papers (1)
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    Developments which led to the observation of spin-wave resonance (SWR) spectra in metallic films are presented. The method is discussed with special emphasis placed on the selection of suitable film samples, the counting of resonance peaks, the assignment of mode numbers, the applicability of inhomogeneity models, and the electromagnetic corrections usually applied to the measured dispersion of the long-wavelength spin-wave peaks. Then, in a review of applications of the method, several points of interpretation which arose subsequent to the publication of the results, are discussed. Finally, some future uses of the SWR method are listed. View full abstract»

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  • Theory of magnetization ripple

    Publication Year: 1968 , Page(s): 32 - 38
    Cited by:  Papers (37)
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    A review is given about the assumptions the development, and the results of the ripple theory. The limits of the linear theory are pointed out. The result of this theory shows a very strong coupling of the magnetization dispersion perpendicular to the mean magnetization, which is caused by the internal demagnetizing field. The exchange constant of this magnetostatic coupling exceeds the quantum mechanical exchange constant A by orders of magnitude. The nonlinear ripple theory includes the component of the internal demagnetizing field parallel to the mean magnetization. This field becomes important when the rms values of the magnetization dispersion are g\approx 2\deg . The nonlinear theory explains all deviations from a single domain behavior without introducing any special model. View full abstract»

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  • Bias susceptibility measurements in thin permalloy films

    Publication Year: 1968 , Page(s): 39 - 40
    Cited by:  Papers (4)
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    Susceptibility measurements at 5000 Hz have been performed in the easy and hard directions on two 80-20 Permalloy films (1000 Å, 1 cm in diameter) cut from large samples. The experimental results agree with the predictions of the Hoffmann theory. The susceptibility parallel to the average direction of M is found to be proportional to 1/(H - H_{k})^{7/4} or 1/(H_{k} - H)^{7/4} when the net field is large enough to prevent blocking. View full abstract»

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  • Review of thin-film switching

    Publication Year: 1968 , Page(s): 41 - 44
    Cited by:  Papers (3)
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    Flux reversal in thin magnetic films with uniaxial anisotropy is known to occur by domain wall motion if the externally applied field is only slightly above the wall motion threshold field. For sufficiently large fields applied at an angle with respect to the easy axis, reversal takes place by coherent rotation. However, the reversal process observed over a substantial field range immediately above the rotational threshold is neither simple wall motion nor simple coherent rotation. Four different models are reviewed which have been proposed for this third type of flux reversal process. These models were developed by Stein, Harte, Vinogradov, and Fuchikami, and it is concluded that no single model offers a complete description of this third process. View full abstract»

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  • One-dimensional walls

    Publication Year: 1968 , Page(s): 44 - 47
    Cited by:  Papers (1)
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    A one-dimensional wall is one in which the magnetization does not vary throughout the thickness of the ferromagnetic film nor along the length of the wall. There are three types of one dimensional walls: Bloch, Néel, and intermediate. The results of calculations of the structure, width, and type of walls as a function of film thickness and wall angle are discussed. The Néel wall width is inversely proportional to wall angle and to film thickness plus a constant. The Bloch wall width is proportional to the square root of film thickness plus a constant. The transition between Néel and intermediate walls is marked by an abrupt change of slope in the hard-axis hysteresis loop. View full abstract»

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  • Recent developments in lorentz electron microscopy

    Publication Year: 1968 , Page(s): 48 - 50
    Cited by:  Papers (2)
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    Several different methods of obtaining contrast for electron microscopy of magnetic specimens are reviewed. For the investigation of magnetization ripple and the structure of domain walls in magnetic films, two questions must be considered: the correct wave optical interpretation of Lorentz micrographs and the experimental attainment of coherence of the electron beam. Both questions have been sufficiently explored so that experimental results on magnetic film microstructure may be expected in the near future. View full abstract»

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  • Magnetooptical investigations on thin ferromagnetic films

    Publication Year: 1968 , Page(s): 51 - 54
    Cited by:  Papers (2)
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    Various applications of the Faraday and Kerr effects for the investigation of domain structures and reversal mechanisms in thin ferromagnetic films are reviewed. Different optical arrangements for the observation of domains are described and compared. Using magnetooptic microscopy domains and wall structures can be observed with a resolution of 1 μm. Magnetization structures give rise to diffraction phenomena, which are revealed as Fresnel fringes, Fraunhofer patterns, and dark field pictures. Applications of these phenomena and the consequences for the resolution of magneto-optic microscopy are discussed. Various kinds of reversal processes by wall motion or rotation, respectively, can be distinguished from each other by measuring the light intensity in two settings of the analyzer and by a dark field method. These reversal mechanisms can be identified even in case of fast switching when direct observations are not possible. Since the applications of magnetooptics are not restricted by any temperature limit, they are especially suited for the investigation of temperature dependent phenomena, e.g., the Barkhausen effect and the magnetic aftereffect. A picture of a domain structure in a gadolinium film at 80°K is shown. View full abstract»

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  • Effect of heat treatment on the electrical resistivity of lithium ferrite

    Publication Year: 1968 , Page(s): 55 - 58
    Cited by:  Papers (1)
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    Polycrystalline lithium ferrite samples were subjected to a variety of heat treatments. The most effective process in raising the sample resistivity was the oxidation process. The efficiencies of these heat treatment processes were compared. Effects of heat treatments on the thermoelectric, microwave line width, and dielectric properties of the samples were also reported. View full abstract»

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  • Effect of a composition gradient on the magnetoelastic sensitivity of Ni-Fe films

    Publication Year: 1968 , Page(s): 59 - 62
    Cited by:  Papers (2)
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    Measurements of the magnetoelastic sensitivity of electrodeposited 1 μ cylindrical Ni-Fe films indicate that the magnetostriction of these films becomes more positive upon annealing. A composition gradient has been observed through the thickness of these films. In addition, electron diffraction results indicate that the composition gradient is substantially reduced during an anneal at 250 °C. To understand the change in magnetoelastic sensitivity the effect of the composition gradient has been considered. The change in the magnetoelastic sensitivity due to the elimination of the composition gradient is shown to be in agreement with observed changes. View full abstract»

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  • A dynamic model of a switching twistor wire segment

    Publication Year: 1968 , Page(s): 63 - 70
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    A semi-empirical differential equation for the local dynamic behavior of a twistor wire is combined with demagnetization equations to yield a set of equations that describe, to the first order, the dynamic switching of a twistor wire segment. The dynamic equation expresses M as a function of M , H , and H , contains several adjustable parameters, and has solutions which agree with most of the observed first-order magnetic switching phenomena. When coupled with the demagnetization equations described in an earlier paper, a complete solution of the average M(z,t) , together with the demagnetizing field Hd(z,t) is readily generated by standard numerical methods. A solution so generated appears to be realistic, though experimental verification has not been attempted. View full abstract»

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  • Application of micromagnetics to a boundless plate

    Publication Year: 1968 , Page(s): 70 - 74
    Cited by:  Papers (3)
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    The case of magnetization reversal in a boundless plate of magnetically homogeneous material is treated in the framework of micromagnetics. It is assumed that the magnetocrystalline symmetry axis and the applied field lie along the normal of the plate surface. The mathematical analysis performed facilitates the determination of the nucleation field in an exact analytical way, leading to the conclusion that nucleation takes place by spin rotation in unison. Some indirect experimental evidences are discussed. View full abstract»

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  • [Back cover]

    Publication Year: 1968 , Page(s): 0
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    Freely Available from IEEE
  • Extremely high density magnetic information storage

    Publication Year: 1968 , Page(s): 75
    Cited by:  Papers (2)  |  Patents (1)
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    First Page of the Article
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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.

Full Aims & Scope

Meet Our Editors

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