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Showing papers on "Magnetic anisotropy published in 1968"


Journal ArticleDOI
TL;DR: In this article, a review is given about the assumptions the development, and the results of the ripple theory, where the limits of the linear theory are pointed out and the nonlinear ripple theory is explained without introducing any special model.
Abstract: 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 \gapprox 2\deg . The nonlinear theory explains all deviations from a single domain behavior without introducing any special model.

194 citations


Journal ArticleDOI
TL;DR: In this article, single crystals of MnSb with various Mn compositions in e phase were prepared successfully with Bridgeman method and magnetization and torque measurements were made on these crystals in temperatures ranging from 4.2°K to 800°K.
Abstract: Single crystals of MnSb with various Mn compositions in e phase were prepared successfully with Bridgeman method. Magnetization and torque measurements were made on these crystals in temperatures ranging from 4.2°K to 800°K. The temperature dependence of saturation magnetization on the sample with 48.2 at. % Mn was in good agreement with Brillouin function of J =3/2∼2, but the samples with Mn rich composition exhibited slight discrepancies from this function. The saturation magnetization per Mn atom at 0°K in Bohr magneton decreases with increasing Mn composition, and these values are well explained quantitatively as excess Mn atoms with 2.2µ B occupy the B site and these spins are arranged antiparallel to those of A site Mn with 3.5µ B . The temperature dependences of the first order crystal magnetic anisotropy of various Mn compositions exhibit analogous function with those of cobalt and nickel derived from Carr's theory.

125 citations


Journal ArticleDOI
TL;DR: In this paper, the change in the easy axis of magnetization observed in some ferrimagnets has been studied using a phenomenological description, and it was found that two second-order phase transitions can occur.
Abstract: The change in the easy axis of magnetization observed in some ferrimagnets has been studied using a phenomenological description. It is found that two second-order phase transitions can occur.

112 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of experimental methods and the design of an appropriate torquemeter made it possible to improve by several orders of magnitude the accuracy of anisotropy measurements.
Abstract: An analysis of experimental methods and the design of an appropriate torquemeter made it possible to improve by several orders of magnitude the accuracy of anisotropy measurements. The experiments performed on nickel between 100°K and the Curie point allowed, for instance, the determination of the eighth‐order anisotropy constant K3 within a few percent. The anisotropy constants K1, K2, and K3 are found to be negative in this whole temperature range. An explanation is given of the main discrepancies in published data between the numerous determinations of anisotropy constants by static methods. The influences of both anisotropy of energy and anisotropy of magnetization are separated and measured as functions of applied magnetic field and temperature in the above‐mentioned range. This interpretation of torque measurements has been confirmed by a direct determination of anisotropic magnetization of nickel at room temperature, and an absolute measurement of the saturation magnetization of nickel at 20°C has ...

92 citations


Journal ArticleDOI
TL;DR: In this article, the results and interpretation of some Mossbauer experiments on FeCr2O4, FeV2O 4, and GeFe 2O4 are discussed.
Abstract: We discuss here the results and interpretation of some Mossbauer experiments on FeCr2O4, FeV2O4, and GeFe2O4. A detailed study of the thermal variation of the spectra leads to a determination of both quadrupolar coupling and hyperfine field at the 57Fe nucleus as a function of temperature. Knowing the local symmetry around the Fe2+ ion, which is tetragonal in the first two cases, and trigonal in the last one, it is possible to deduce from the quadrupolar coupling the form of the lowest orbital wavefunction of the Fe2+ ion. In FeCr2O4 and FeV2O4, this may be combined with the optical data obtained by Slack on the very similar compound FeAl2O4, to predict the form and magnitude of the spin Hamiltonian and magnetic anisotropy, as well as that of the hyperfine field tensor (using a reasonable estimate for the core hyperfine field). In GeFe2O4 similar predictions can be made after deducing the distance to the first excited orbital level from the thermal variation of e2qQ. The interest of such calculations in c...

83 citations


Journal ArticleDOI
TL;DR: In this paper, the magnetic anisotropy of spherical Fe-Ni (50-50) single crystals were ordered by neutron irradiation at 295°C in the presence of a magnetic field.
Abstract: Spherical Fe–Ni (50–50) single crystals were ordered by neutron irradiation at 295°C in the presence of a magnetic field. Magnetization curves and magnetic anisotropy energy measurements demonstrate the very important directional effect of the irradiation magnetic field on the bulk anisotropy of the single crystal. When the magnetic field is applied along a fourfold axis, the bulk magnetic anisotropy is tetragonal with a very large value for K3. When the magnetic field is applied along a three fold axis, the bulk magnetic anisotropy is cubic and the threefold axis becomes an easy axis of magnetization; the magnetization measured along the easy direction reaches saturation with a certain law of approach, while the magnetization measured along the [100] direction reaches saturation immediately. The model proposed by Neel, in which three types of quadratic ordered domains are assumed to be strongly coupled, fits well the experimental results. An electron microscopy image shows the different type of ordered d...

80 citations


Journal ArticleDOI
TL;DR: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data as mentioned in this paper, using Pioneer data sets.
Abstract: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data

54 citations


Journal ArticleDOI
TL;DR: In this paper, changes in the magnetization curves, magnetic susceptibility, and remanent magnetization of magnetite and titaniferous magnetite under uniaxial compression are experimentally examined in a systematic way.
Abstract: Changes in the magnetization curves, magnetic susceptibility, and remanent magnetization of magnetite and titaniferous magnetite under uniaxial compression are experimentally examined in a systematic way. The uniaxial compression results in a reduction of the intensity of magnetization and the magnetic susceptibility of both single crystals and assemblages of fine grains of titaniferous magnetite.However, a removal of the compression from the samples in presence of a magnetic field results in an abrupt increase of magnetization, the resultant intensity of magnetization being larger than the ordinary magnetization without the effect of compression in the same field. The majority of the increased magnetization remains as the remanent magnetization after removal of the field. Thus, the isothermal remanent magnetization produced by removing uniaxial compression in a magnetic field increases with increasing magnitude of the uniaxial compression.

48 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied the magnetic behavior in the transition region using both torque and vibrating sample magnetometers with applied fields (Ha) from about 0.1 to 6.0 kG.
Abstract: In a number of canted‐spin rare earth (RE) orthoferrites, the easy axis for the spontaneous magnetization changes from the a to the c axis with increasing temperature. We have studied the magnetic behavior in the transition region using both torque and vibrating sample magnetometers with applied fields (Ha) from about 0.1 to 6.0 kG. The measurements were made with Ha in the ab, bc, and ac planes. The use of small values of Ha makes it possible to separate the effects of the weak ferromagnetism from the paramagnetism of the RE lattice. In Sm orthoferrite the reorientation occurs over about 20°, centered at 175°C (Tr). For this material in the ac plane the iron lattice is well described by the energy expression E = +½Ku cos2θ+kb cos4θ. Substantially below Tr, Ku≫Kb and the magnetization has a strong uniaxially preferred axis along a. As the temperature increases, Ku decreases and the easy axis splits symmetrically in two, one on each side of a, and these rotate toward c with increasing T. At 175°C, Ku∼0 and...

47 citations


Journal ArticleDOI
TL;DR: In this paper, a review of the characteristics of the anisotropy found in thin Fe-Ni-Co films that are important from a practical viewpoint are presented, and previously published data are supplemented to form a composite ternary diagram of anisotropic field Hk as a function of composition for the alloy system Fe−NiCo for 250°C substrate temperature.
Abstract: A review of those characteristics of the anisotropy found in thin Fe–Ni–Co films that are important from a practical viewpoint are presented. Previously published data are supplemented to form a composite ternary diagram of anisotropy field Hk as a function of composition for the alloy system Fe–Ni–Co for 250°C substrate temperature. Anisotropy fields as a function of composition for the three binary alloy systems at other substrate temperatures are included. A composite diagram showing anisotropy field as a function of measuring temperature illustrates the need for temperature stability. Magnetic annealing and aging is discussed. Finally the importance of magnetostriction as a source of the anisotropy is discussed in detail as well as pair ordering. It is concluded that no single source or combination satisfactorily describes the origin of the anisotropy.

45 citations


Journal ArticleDOI
TL;DR: In this paper, the present status of the theories of magnetic anisotropy is reviewed, and a discussion of the origins of magnetic anomalous behavior in some typical cases is given.
Abstract: Microscopic considerations on magnetic anisotropy are described, and through discussion of the origins of magnetic anisotropy in some typical cases, the present status of the theories of magnetic anisotropy is reviewed.

Journal ArticleDOI
TL;DR: In this paper, the magnetic anisotropy, average susceptibility, and g values have been measured on several Cu(II) N, N dialkyldithiocarbamates where the Cu ion has been shown to be in a square pyramidal environment.
Abstract: The method of measuring the magnetic anisotropy of single crystals is briefly described, and a suitable calibrant for this type of work is suggested. The magnetic anisotropy, average susceptibility, and g values have been measured on several Cu(II) N, N dialkyldithiocarbamates where the Cu ion has been shown to be in a square pyramidal environment. The magnetic anisotropy is very low, while the principal molecular susceptibilities (K‖ and K⊥) obey a Curie–Weiss Law with θ ≃ 10°K between 80°–300°K. The single crystal g values and the average moments are very close to the spin‐only values. The linewidth of the diethyl and di‐n‐butyl derivatives shows an unusual narrowing which is partly attributed to an exchange interaction through the bridging sulfur atoms within the Cu dimer unit. The expressions for K‖ and K⊥ have been deduced, and the experimental data has been fitted. The ligand‐field parameters are greatly reduced from their free‐ion values, the spin–orbit coupling constant, the orbital reduction para...

Journal ArticleDOI
TL;DR: Magnetic moment measurements have been made along principal axes of Dy, Er, Ho, Tb, and Gd single crystals at 4.2°K and dc fields to 150 kOe as mentioned in this paper.
Abstract: Magnetic‐moment measurements have been made along principal axes of Dy, Er, Ho, Tb, and Gd single crystals at 4.2°K and dc fields to 150 kOe. Dy and Tb showed similar magnetic properties. Saturation along the easy axis was achieved at low fields, while along the hard (c) axis the moment was nearly linear with field and did not approach saturation. Anisotropy was observed in the basal plane at low fields. An irreversible change in Dy and Tb occurred below 150 kOe for fields along the hard axis, such that subsequently saturation could not be achieved along the easy axis. Extrapolation of the low‐field (unstrained) data along the hard axis indicated anisotropy energies of about 109 ergs/cm3. In Er significant modifications of the zero‐field conical moment state were observed and theoretical saturation was almost achieved along the c axis. Fields applied in basal‐plane directions collapsed the conical state and produced fan‐moment distributions approaching saturation near 150 kOe.

Journal ArticleDOI
J. Becker1
TL;DR: The properties of Alnicos and elongated single-domain fine-particle materials, both interpreted as due to shape anisotropy of fine particles, are still far short of those predicted by simple theory as discussed by the authors.
Abstract: The properties of Alnicos and elongated single-domain fine-particle materials, both interpreted as due to shape anisotropy of fine particles, are still far short of those predicted by simple theory. The hard ferrites, with properties due to magnetocrystalline anisotropy, come much closer, but are restricted by their low magnetization. The search for a combination of high magnetization and high magnetocrystalline anisotropy has led to the investigation of a variety of intermetallic compounds. Some of them, particularly the cobalt-rare earths, appear quite promising. Mechanical grinding often has an adverse effect on the magnetic properties of crystal anisotropy materials. Chemical stability is also often a problem. Crystal anisotropy materials in general have high values of intrinsic coercive force. This makes them especially suitable for applications involving widely varying dynamic conditions. Their proper evaluation may be best done using criteria other than the usual maximum energy product.

Book ChapterDOI
Masao Kotani1
TL;DR: In this paper, the in-plane magnetic anisotropy of heme has been studied in the high-spin state and in the low-spin states, and it has been shown that if the magnetic field is applied parallel to the heme plane and is rotated in the same plane, g values of electron paramagnetic resonance absorption (EPR) signal vary sinusoidally between maximum and minimum values.
Abstract: Publisher Summary This chapter discusses in-plane magnetic anisotropy of heme, both in the high-spin state and in the low-spin state. If the magnetic field is applied parallel to the heme plane and is rotated in the same plane, g values of electron paramagnetic resonance absorption (EPR) signal vary sinusoidally between maximum and minimum values. The absolute directions of these principal axes of in-plane anisotropy, in reference to the geometrical structure of heme, are not certainly known. Studies show that for ferri-MbF– (high-spin) and ferri-Mb.N3– (low-spin) these principal axes do not coincide, but those for fluoride and azide make an angle of about 45°. To show this, a single crystal of ferri-Mb was prepared, in which hydrogen fluoride and sodium azide was added simultaneously to the crystal. Then some of the hemes catch F– and some N3–, and signals from high-spin hemes and those from low-spin hemes could be observed on the same crystal. On the assumption that the attachment of F– and N3– does not affect the geometry of hemes, it was possible to compare the directions of principal axes of anisotropy of two derivatives. By constructing a Lissajous-like plot, it has been shown that the principal axes of high-spin heme and those of low-spin hemes make an angle of about π/4.

Journal ArticleDOI
TL;DR: In this article, stress induced anisotropy has been determined for several natural crystals of hematite for compressions of up to 300 Kg/cm2 along the trigonal axis and along different directions within the basal plane.
Abstract: The stress induced anisotropy has been determined for several natural crystals of hematite for compressions of up to 300 Kg/cm2 along the trigonal axis and along different directions within the basal plane. The induced anisotropy is predominantly uniaxial, but substantial higher harmonics are present for compressions along the trigonal axis. It is larger for compressions within the basal plane in accordance with the magnetostriction experiments of Urquhart and Goldman. Stress induced anisotropy as a possible explanation of the high coercive forces of hematite powders is discussed, as shape and intrinsic crystalline anisotropy are negligible.

Journal ArticleDOI
TL;DR: The dc and microwave magnetic properties of single crystals of Ba4Zn2Fe36O60(ZnU) were investigated in this paper, where the saturation magnetization, anisotropy constant and anisotropic field were determined as a function of temperature from 42 to 600°K.
Abstract: The dc and microwave magnetic properties of single crystals of Ba4Zn2Fe36O60(ZnU) were investigated The saturation magnetization ‖ and ⊥ to c, anisotropy constant and anisotropy field were determined as a function of temperature from 42 to 600°K TC = 673±2°K At room temperature 4πMs = 3700 G, K1 = 14×106 ergs/cm3 and HA = 96 kOe At 42°K 4πMs = 6190 G, K1 = 24×106 and HA = 10 kOe A magnetic moment nβ = 60 was computed from a collinear spin model, excellent agreement with nβ = 605, calculated from σs(H = ∞, T = 0) This result tends to confirm allignment of spins ‖ to c Ferrimagnetic resonance linewidths of 210 Oe were measured on unpolished samples in the range 30–40 GHz An anisotropy in electrical resistivity of 107 Ω·cm ‖ and 4×103 Ω·cm ⊥ to c was noted

Journal ArticleDOI
TL;DR: In this article, the magnetic moment of pure iron manganite FeMn2O4 was measured at 4.2°K and showed that the inversion parameter is 0.91 (nearly inverse spinel).
Abstract: Pure iron manganite FeMn2O4 was prepared at 1250°C and quenched. It crystallizes in the b.c. tetragonal system D4h19. Neutron diffraction measurements above the Curie temperature (120°C) show that the inversion parameter is 0.91 (nearly inverse spinel). The spontaneous magnetization at 4.2°K measured in high static and pulsed fields is 1.55 μB/mol. The magnetic moment was observed to increase linearly above 70 kOe and showed the presence of a strong anisotropy with easy axis near the [101] direction (unusual fact). Neutron diffraction measurements at 4.2°K lead to the determination of the magnetic structure of FeMn2O4. The tetrahedral sublattice moments (4.3 μB) are collinear in a (010) plane making an angle of − 172° with Ox [100]. Spins in octahedral sites (3.1 μB) are divided into four magnetic sublattices with a pyramidal arrangement whose axis of symmetry lies in the plane (010) and makes an angle of 14° with Ox [100]. At 55°K the spins of the octahedral sublattices become collinear, the easy magneti...

Journal ArticleDOI
TL;DR: The anisotropy of the magnetic susceptibility of type A ferrimyoglobin single crystals was measured by a highly sensitive torque meter from liquid-N2 temperature down to the temperature of pumped liquid He with good agreement with those obtained from the mean magnetic susceptibility measurements.

Journal ArticleDOI
TL;DR: In this paper, the authors found that a particular distribution of residual microstress, in which most of the volume of the specimen is in residual compression, balanced by a small volume in tension, after plastic elongation, causes magnetoelastic effects which do not cancel in a nonsaturated specimen, and thereby cause the observed anisotropy.
Abstract: Previous plastic elongation, or compression, of polycrystalline nickel was found to produce a uniaxial anisotropy. The easy axis of magnetization was parallel to the axis of previous elongation and at right angles to the axis of previous compression. The maximum value of the uniaxial anisotropy energy constant Ku was about 2700 erg/cm3 after 2.5% elongation. The observed anisotropy is shown to be due to a particular distribution of residual microstress, in which most of the volume of the specimen is in residual compression, balanced by a small volume in tension, after plastic elongation. These stresses, although balanced, introduce magnetoelastic effects which do not cancel in a nonsaturated specimen, and which thereby cause the observed anisotropy. Evidence for the assumed stress distribution was obtained by x‐ray diffraction.

Journal ArticleDOI
TL;DR: In this article, a spin-density Patterson synthesis was used to obtain a model of the structure of an antiferromagnet with Neel temperature 103°K, which was refined by a least squares procedure and gave very good agreement with the observed magnetic reflections.
Abstract: Mn2P has been found to be an antiferromagnet with Neel temperature 103°K. The magnetic structure has been determined by neutron diffraction studies of single crystals. A model of the structure was obtained directly from the diffraction intensities by means of a spin-density Patterson synthesis. This model was refined by a least-squares procedure and gave very good agreement with the observed magnetic reflections. The structure consists of a spin modulation commensurate with the lattice propagating along three hexagonally equivalent directions. The spins are all perpendicular to the propagation directions and the mean values of magnetic moments at the two manganese sites are MnI: 0·01 ± 0·04μB, MnII: 0·84 ± 0·03μB. The possible existence of spin domains has been examined by cooling the crystal through the Neel point in a large magnetic field and remeasuring the magnetic reflections. However, no evidence for their existence was found.

Journal ArticleDOI
J. Slonczewski1
TL;DR: A survey of experimental results for magnetic anisotropy induced during evaporation and annealing of polycrystalline Ni-Fe alloy films is given in this article.
Abstract: 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.

Journal ArticleDOI
TL;DR: Based on the electronic energy state of Fe2+ ion in the crystalline fields in Fe7S8 and Fe7Se8 (4c) with a pseudo NiAs structure, the expression of magnetic anisotropy energy were derived by perturbation method under an appropriate approximation.
Abstract: Based on the electronic energy state of Fe2+ ion in the crystalline fields in Fe7S8 and Fe7Se8 (4c) with a pseudo NiAs structure, the expression of magnetic anisotropy energy were derived by perturbation method under an appropriate approximation. Then the experimental results of magnetization curves were analyzed from this theory and the physical constants for the anisotropy energy, such as orbital angular momentum in the lowest state and the anisotropy energies of the second‐ and the fourth‐order, were estimated. Using these constants, the experimental results of the temperature dependence on the spin angle (the second‐order transformation) without magnetic field were well explained. On the other hand, a possibility of the occurrence of the first‐order phase transformation for spin angle appearing in Fe7Se8 (3c) and FeS (α‐point) was discussed from the same basis of the theory, and was given an explanation for the nuclear quadrupole shift at this transformation point in the Mossbauer experiment.

Journal ArticleDOI
TL;DR: In this article, a two-sublattice model was proposed to describe the angular dependence of the resonance lines in cubic-to-rhombohedral phases of FeF3.
Abstract: Resonance studies at 70 GHz have been performed in crystals of FeF3 from liquid‐helium temperature to 400°K. Below 367°K the field for resonance is anisotropic and temperature dependent. Because of a high‐temperature cubic‐to‐rhombohedral phase transition, the observed spectra of the twinned samples consist of superpositions of the resonance lines resulting from single crystals with c axes parallel to each of the four 〈111〉 directions of the cubic unit cell. The angular dependence is well described by a two‐sublattice model applied to each of the single‐crystal orientations. The model contains symmetric and antisymmetric exchange interactions and a weak anisotropy field parallel to the c axis. Both high‐ and low‐frequency modes have been observed. The effective fields used in the two‐sublattice model have been obtained as functions of temperature from the resonance data at special applied field orientations. It is found that the c axis is a hard direction of magnetization between the Neel point and 251°K and changes to an easy axis at low temperatures. This effect is interpreted as a result of competing sources of anisotropy. Good agreement is found between the AFMR results and temperature dependences calculated using the molecular‐field approximation.

Journal ArticleDOI
TL;DR: In this paper, the maximum and minimum energies of a uniaxial single domain particle under an applied field are calculated for a range of orientations of easy axis to field from 0°-90° of arc.
Abstract: The difference between the maximum and minimum energies of a uniaxial single domain particle under an applied field is calculated for a range of orientations of easy axis to field from 0°–90° of arc. From this table the critical fields for discontinuous magnetization rotation over a range of temperatures can be deduced. The remanence coercivity of a randomly oriented array of such particles is plotted from the data.

Journal ArticleDOI
TL;DR: In this article, it was shown that TbAu2 exhibits a linear transverse wave spin alignment propagating along the a axis (the face centered description) and polarized in the c axis direction, and the wavelength of this static magnetization wave is incommensurable with the atomic repetition.
Abstract: Neutron‐powder‐diffraction study has shown that, in the range 55°‐42.5°K, TbAu2 (tetragonal, iso‐structural to MnAu2) exhibits a linear‐transverse‐wave spin alignment propagating along the a axis (the face‐centered description) and polarized in the c axis direction. The wavelength of this static magnetization wave is incommensurable with the atomic repetition and varies 1.200‐1.186 in a spacing units in the range 55°‐42.5°K. The rms moment per Tb at 42.6°K is 5.1 Bohr magnetons. At just below 42.5°K, a first‐order magnetic transition takes place and the wavelength of the transverse wave abruptly becomes equal to the a spacing. The resulting antiferromagnetic structure persists down to 2°K and the saturation moment is practically identical to the ordered moment of the free Tb3+ ion, 9.0 Bohr magnetons. The crystallographic data in the range 300°‐5°K are also presented.

Journal ArticleDOI
Hideo Fujiwara1, Y. Sugita
TL;DR: In this paper, the existence of origins of perpendicular anisotropy other than the ordinary magnetostrictive effect is presented with a brief review of other studies and the effect of the grain boundaries or the microscopic shape effect is discussed.
Abstract: 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.


Patent
26 Aug 1968
TL;DR: A method of high-density MAGNETIC RECORDING as mentioned in this paper is a method of using a high-density high-dimensional magnetic recording head to support block walk.
Abstract: A METHOD OF HIGH-DENSITY MAGNETIC RECORDING USING A MAGNETIC RECORDING HEAD HAVING A RECORDING GAP THAT IS INCUDTIVELY COUPLED TO A RELATIVELY MOVING OR STATIONARY THIN-FERROMAGNETIC-FILM RECORDING MEDIUM OF A THICKNESS THAT IS INSUFFICIENT TO SUPPORT BLOCK WALLS, I.E., CAN ONLY SUPPORT NEEL WALLS, BETWEEN ADJACENT DOMAINS AND HAVING AN EASY AXIS THAT IS ORTHOGONAL TO THE DIRECTION OF RELATIVE MOVEMENT OR PARALLEL TO THE RECORDING GAP. THE RECORDING MEDIUM''S INTERDOMAIN NEEL WALLS ARE FORMED WITH THE MAGNETIZATION WITHIN THE WALLS HAVING THE SAME DIRECTIONA ROTATIONAL, I.E., WINDING, SENSE, E.G., CLOCKWISE OR COUNTERCLOCKWISE, BY APPLYING FIRST OR SECOND AND OPPOSITE POLARITY ORTHOGONAL FIELDS HL AND JT IN THE RECORDING GAP.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the origin of the induced anisotropy in evaporated Permalloy films of the composition ranging from 70-to 90-percent Ni, and the compositional dependence of contributions from each origin can be used in order to elucidate the whole mechanism of the anisotropic in detail.
Abstract: Variation of H k during isothermal magnetic annealing has been systematically investigated to make clear the origin of the induced anisotropy in evaporated Permalloy films of the composition ranging from 70- to 90-percent Ni. The anisotropy of films deposited at room temperature comes from six different origins, whose activation energies are E_{1} eV (0.17-0.2 eV), E_{2} \simeq E_{3} \simeq 0.5 eV, E_{4} \simeq E_{5} \simeq 1.1 eV, and E_{6} = 2.0 eV, respectively. The compositional dependence of contributions from each origin can be used in order to elucidate the whole mechanism of the anisotropy in detail. The component of activation energy from 0.2 to 0.5 eV is closely related to the magnetoelastic anisotropy, while that of 1.1 eV is almost independent of the film composition. The component with the activation energy of 2.0 eV proved to be the same as that found in bulk Permalloy. Furthermore, the effects of the preparation condition of films on the anisotropy are also discussed.