Showing papers on "Magnetic anisotropy published in 1984"
01 Apr 1984
Abstract: Spend your few moment to read a book even only few pages. Reading book is not obligation and force for everybody. When you don't want to read, you can get punishment from the publisher. Read a book becomes a choice of your different characteristics. Many people with reading habit will always be enjoyable to read, or on the contrary. For some reasons, this theory of electromagnetic waves tends to be the representative book in this website.
185 citations
TL;DR: The magnetic properties of rapidly quenched FeRM alloys where R=La,Y,Pr,Nd,Gd and M=B,Si,Al,Ga,Ge have been investigated over a wide range of chemical compositions as discussed by the authors.
Abstract: The magnetic properties of rapidly quenched FeRM alloys where R=La,Y,Pr,Nd,Gd and M=B,Si,Al,Ga,Ge have been investigated over a wide range of chemical compositions. The samples are generally magnetically soft in the as‐quenched state. Magnetic hardening is produced by annealing the samples around 700 °C. The best properties have been obtained in samples containing Pr and Nd together with B and Si. An energy product of 13 MGOe and a coercive field of 15 kOe have been obtained in a Fe76Pr16B5Si3 sample. The higher Fe content samples appear to be more promising with a potential energy product of 49 MGOe. Thermomagnetic data show that a structural transformation takes place upon heating the samples to 700 °C. The Curie temperature of the as‐quenched phase is around 160 °C while that of the new phase is around 320 °C. Transmission electron microscope studies show fine precipitates (∼100 A) dispersed in a matrix of different chemical composition. X‐ray and electron diffraction data indicate that the precipitates have the Fe21R3B tetragonal structure. The high anisotropy of this phase together with its fine size and distribution give rise to the observed high coercive fields.
153 citations
TL;DR: The Mössbauer spectroscopy and electron microscopy data have shown that the magnetic anistropy constant of haemosiderin is considerably larger than that of ferritin, which is thought to result from the smaller core size and less symmetrical protein shell of the former.
143 citations
TL;DR: In this article, the saturation magnetization Js(T, D) of the Ni(111) films was analyzed using a high sensitivity torsion oscillation magnetometer working in UHV.
119 citations
TL;DR: In this article, the structural and magnetic behavior of selected metalloid (B,C) containing hexagonal and tetragonal rare earth-transition metal compounds and compound series was investigated.
85 citations
TL;DR: In this paper, the saturation magnetization, uniaxial anisotropy, optical absorption α, Faraday rotation θF, and the Faraday ellipticity ψF of epitaxial garnet films of composition Y3−xBixFe5−yAlyO12 were investigated for x≤1.34 and y≤2.22.
Abstract: The saturation magnetization Ms, the uniaxial anisotropy Ku, the optical absorption α, the Faraday rotation θF, and the Faraday ellipticity ψF of epitaxial garnet films of composition Y3−xBixFe5−yAlyO12 have been investigated for x≤1.34 and y≤2.22. The temperature dependence of Ms and θF at λ=633 nm have been measured in the range 4.2 K≤T≤TC. Ku, TC, θF, and ψF reveal a linear dependence on the bismuth content. The dependence of θF and ψF on the aluminum concentration shows that both sublattices are involved and indicate that the magneto‐optical effects have to be ascribed to iron pair transitions. The magnitude of the growth‐induced anisotropy is essentially controlled by the supercooling ΔTs and increases linearly with ΔTs. The obtainable magnetic and magneto‐optical data for magneto‐optical applications are discussed and compared with those of garnet films exhibiting a compensation temperature.
82 citations
TL;DR: In this article, a magnetic characterization of the CO 1-x Pt x system with 0.8 anisotropy field has been made, and the solid state transformation diagram at low Pt content has been completed by using the thermomagnetic analysis.
Abstract: A magnetic characterization of the CO 1-x Pt x system with 0\leqx\leq0.8 has been made. The anisotropy field (H A ) of both the hard magnetic phases, i.e. hexagonal at low Pt content and tetragonal around the equiatomic composition, has been measured by the singular point detection technique (SPD). The dependence of H A on composition and temperature is given. The solid state transformation diagram at low Pt content has been completed by using the thermomagnetic analysis (TMA).
78 citations
TL;DR: Cylindrical giant vesicles prepared from egg lecithin and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) are observed by phase contrast microscopy and the anisotropy of DMPC is found to be larger by a factor of 2 than that of egg leCithin.
73 citations
TL;DR: In this paper, it is shown that there are several minimum energy states available to grains and that the lowest energy state does not appear to be occupied, based on comparisons between theory and observations of domains.
71 citations
TL;DR: In this paper, the development of planar and linear fabrics due to Alpine deformation in Dogger calcareous shales has been studied using measurements of the anisotropy of magnetic susceptibility.
68 citations
TL;DR: In this article, the magnetization processes in electrical steel sheets in rotating and alternating magnetic fields up to 1.8 T can be investigated with an instrument which is described in this paper.
Abstract: The magnetization processes in electrical steel sheets in rotating and alternating magnetic fields up to 1.8 T can be investigated with an instrument which is described in this paper. The components of the vectors of the magnetic induction \vec{B} and the magnetic field strength \vec{H} are measured wlth four sensors during one period and processed by a transient recorder and a computer. Some results for rotating fields are presented for a sample of non-oriented silicon steel.
TL;DR: In this article, it was shown that the Curie point of this Ti-stabilized SmFe5 phase should be greater than 600°C and the demagnetizing field in the plane of the thin film samples should be used in obtaining the inplane B field.
Abstract: Samples of the Sm‐Fe system have been directly crystallized onto heated substrates by selectively thermalized sputtering. Films of the pure Sm‐Fe system exhibit only the 1–2, 1–3, and 2–17 phases which correspond to the bulk system. But samples synthesized with certain third element additions of oxygen and titanium exhibit a metastable phase at a composition corresponding to a 1–5 Sm–Fe compound. These samples exhibit well defined and reasonable sharp x‐ray diffraction patterns. Room‐temperature intrinsic coercive forces of 6.2 kOe and static energy products of 5.5 MG Oe have been observed. These results are for the demagnetizing field in the plane of the thin film samples and no demagnetizing factor has been used in obtaining the inplane B field. Samples synthesized in the presence of an inplane magnetic field at 600 °C exhibit an inplane anisotropy which indicates the Curie point of this Ti‐stabilized SmFe5 phase should be greater than 600 °C. Film samples of the pure Sm‐Fe system which do not show a metastable phase generally have low intrinsic coercive forces and consequently low energy products.
TL;DR: In this paper, the composition and temperature dependence of the magnetic anisotropy energy is studied by analysing the approach to saturation of isothermal magnetization as well as by using the singular point detection method.
TL;DR: In this paper, it was shown that magnetic aftereffects and the formation of induced anisotropic magnetic interaction energy resulting from exchange, spin-orbit coupling, and magnetoelastic interactions in amorphous ferromagnetic alloys can be described explicitly.
Patent•
07 Dec 1984
TL;DR: In this paper, a magnetic field sensor is disclosed with which can be used to determine the direction of magnetic field by using the planar Hall effect, where the magnetic field sensors are made of a ferromagnetic amorphous metal.
Abstract: A magnetic field sensor is disclosed with which the direction of a magnetic field can be determined by using the planar Hall effect. An active layer of the sensor is made of a ferromagnetic amorphous metal which is magnetically isotropic. Thus, the magnetization in the active layer always has the direction of an external magnetic field. The developed planar Hall voltage is a measure of the direction of the magnetic field.
TL;DR: In this paper, it was shown that the coercivity of a magnetic recording material is a well-defined parameter only if the time-scale of interest is specified, and that the discrepancy between the two values will become more pronounced as the volume of the magnetic switching unit becomes smaller.
Abstract: The coercivity of a magnetic material is a well-defined parameter only if the time-scale of interest is specified. A measurement that produces rapid changes of magnetization will yield a higher value of the coercivity than one that operates on a longer time-scale. The difference is due to the thermally-assisted nature of the magnetic switching process. Thus, for a magnetic recording material, the coercivity relevant to high-frequency writing will be greater than that relevant to demagnetization processes (such as transition broadening) during long-term storage. The discrepancy between the two values will become more pronounced as the volume of the magnetic switching unit becomes smaller; this effect is relevant to the question of the ultimate information densities achievable by magnetic media. The "writing coercivity" and the "storage coercivity" can be estimated from typical magnetic measurements and simple kinetic theory, for both uniaxial and multiaxial ("isotropic") recording materials.
TL;DR: In this article, an experimental study has been made on the magnetic anisotropy of amorphous TbCo films prepared by rf co-sputtering and it was shown that the planar stress due to the substrate constraint considerably influences the perpendicular anisotropic through the large magnetostriction of about 2×10-4.
Abstract: An experimental study has been made on the magnetic anisotropy of amorphous TbCo films prepared by rf co-sputtering. TbCo films prepared at a substrate bias voltage of –100 V exhibit a large uniaxial anisotropy of 2×106 erg/cm3 with its easy axis perpendicular to the film plane, whereas films prepared without the substrate bias exhibit the anisotropy with its easy axis in the film plane. The planar stress due to the substrate constraint considerably influences the perpendicular anisotropy through the large magnetostriction of about 2×10-4. When films with perpendicular anisotropy are removed from the substrate, the anisotropy energy decreases to 65–80 percent of its initial value. Annealing for one hour at 300°C destroys the perpendicular anisotropy almost completely.
TL;DR: In this paper, a tangent relationship between inclinations of the DRM and ambient magnetic field was confirmed by redeposition experiments of disintegrated hematite bearing sandstone, and the authors attributed variations of DRM-intensities with field inclination to processes acting during the depositional formation of laminated sediments.
Abstract: Redeposition experiments of disintegrated hematite bearing sandstone have confirmed a tangent relationship between inclinations of the DRM and ambient magnetic field. Pronounced variations of DRM-intensities with field inclination are attributed to processes acting during the depositional formation of laminated sediments. Coinciding azimuthal distributions of remanence and maximum susceptibility directions reflect intrinsic properties of flaky hematite grains in which the magnetic moment is parallel to the direction of maximum susceptibility. This parallelism probably depends on magnetic domain configurations.
TL;DR: In this article, the magnetic anisotropy of transition metal poly(yne) polymers was systematically controlled by including different transition metal atoms in the polymer structure, and the results showed that the anisotropic properties of the polymers can be modelled by different metal atoms.
Abstract: High resolution 31P n.m.r. studies of lyotropic liquid crystals formed by transition metal–poly(yne) polymers indicates that the magnetic anisotropy of the polymers may be systematically controlled by including different transition metal atoms in the polymer structure.
TL;DR: The saturation magnetization and the magnetocrystalline anisotropy were measured on single crystals in the solid solution series SrZn 2-x Co x Fe 16 O 27 (SrZn2-xCo x -W) at 298 K and 6 K Lattice constants and Curie-temperatures are also given as a function of the composition as discussed by the authors.
Abstract: The saturation magnetization and the magnetocrystalline anisotropy were measured on single crystals in the solid solution series SrZn 2-x Co x Fe 16 O 27 (SrZn 2-x Co x -W) at 298 K and 6 K Lattice constants and Curie-temperatures are also given as a function of the composition The magnetocrystalline anisotropy changes from uniaxial to planar dependent on temperature and cobalt substitution at x \approx 05 for 6 K and x \approx 085 for 298 K The six-fold anisotropy in the basal plane of the planar W-hexaferrites increases strongly with increasing cobalt content Crystals with a low Co substitution (x = 033 and 067) have an anomalous discontinuity in their hard direction magnetization curves; indicating a first-order magnetization process
IBM1
TL;DR: In this article, the critical properties of spin-1 chains with uniaxial single-ion anisotropy were determined using finite-size scaling to determine critical properties.
Abstract: We use finite-size scaling to determine the critical properties of spin-1 chains with uniaxial single-ion anisotropy $D$. A phase diagram is obtained in the ($D$, $\ensuremath{\Delta}$) plane, where $\ensuremath{\Delta}$ is the strength of the interaction in the direction of the single-ion anisotropy. Critical exponents are estimated.
Patent•
24 Aug 1984TL;DR: In this article, a U-shaped first core member having end faces opposite to the ribbons is provided in the vicinity of the shaft, and an exciting coil for producing a magnetic flux and a detecting coil are wound around the core member, and the magnetic flux produced by the exciting coil and introduced through the ribbon to the core members is detected by the detecting coil.
Abstract: In a torque sensor of a noncontact type for sensing a rotary torque applied to a shaft, a magnetic ribbon of a film shape formed of a magnetic material and applied in advance with an induced magnetic anisotropy in the direction of an angle θ along the circumference of a shaft is bonded to the shaft along its circumference. A U-shaped first core member having end faces opposite to the ribbons is provided in the vicinity of the shaft. An exciting coil for producing a magnetic flux and a detecting coil are wound around the core member, and the magnetic flux produced by the exciting coil and introduced through the ribbon to the core member is detected by the detecting coil. When an exciting current of a predetermined frequency is supplied from an oscillator to the exciting coil to produce a magnetic flux, an output signal is generated from the detecting coil and is measured by a voltmeter.
TL;DR: In this paper, a new type of uniaxial particles for magnetic recording whose precursors are produced via an original hydrothermal process was recently introduced in the market.
Abstract: A new type of uniaxial particles for magnetic recording whose precursors are produced via an original hydrothermal process was recently introduced in the market. The characterizing feature of these materials is their extremely uniform size and ellipsoidal shape. Most of their properties can be ascribed to the lack of external (pores, dendrites, sharp edges) as well as internal (because of ellipsoidal shape) - self-demagnetizing sources, which suggests the name of "Non-Polar (NP)" particles. As a result of this morphology, they show unique magnetic properties. The magnetization reversal mechanism is not accounted for by any known mechanism as fanning or curling and the rotational hysteresis gives very sharp W r vs. H curves with the lowest values for the integral ever measured for particulate media. The behaviour of coercivity versus packing fraction for Cobalt-surface-modified NP particles is described by a new "constricted magnetization" model. The reasons for these unique characteristics and the practical impact that these materials may have in the field of magnetic recording are discussed.
TL;DR: In this paper, the magnetic moment per formula unit of CoPt increases with dilution which is attributed to a platinum moment of ≊ 0.3μB over the entire range of compositions.
Abstract: Crystalline films of CoxPt1−x were prepared over the range of x=0.26 to 0.84 atomic fraction by rf sputtering. Magnetization measurements show a wide range of anisotropy conditions including perpendicular anisotropy at intermediate compositions. The magnetic moment per formula unit of Co‐Pt increases with dilution which we attribute to a platinum moment of ≊0.3 μB over the entire range of compositions. The Hall effect and anisotropic magnetoresistance are both large at x≊0.4.
TL;DR: In this paper, specific heat measurements on a spherically shaped single crystal of the dipolar Ising ferromagnet LiHoF4 for various values of a magnetic field applied along the c-axis (easy axis) are presented.
TL;DR: In this paper, the magnetic properties of sputtered cobalt-chromium films were evaluated over a composition range of 12.8 at percent to 23.5 at percent chromium.
Abstract: The magnetic characteristics of sputtered cobalt-chromium films were evaluated over the composition range of 12.8 at percent to 23.5 at percent chromium. The saturation magnetization was greater for sputtered films than for similar bulk alloys at chromium contents greater than about 10 at percent. The second order anisotropy constant, K 2 is only a few percent of the first order anisotropy constant, K 1 and therefore, the intrinsic perpendicular anisotropy energy is sufficiently determined by K 1 for compositions with Ku>O. The value of K 1 decreases with increasing Cr concentration. The anisotropy energy, Ku is negative below a chromium content of 20.5 atomic percent and positive above this value.
TL;DR: In this paper, the authors compared the most common methods for assessing the switching field distribution (SFD) of magnetic recording media for samples of acicular magnetic particles made of different types of magnetic materials and having various degrees of particle orientation.
Abstract: The most common methods for assessing the switching field distribution (SFD) of magnetic recording media are compared for samples of acicular magnetic particles made of different types of magnetic materials and having various degrees of particle orientation. It is shown that the method of using the maximum slope dM/dH = M_{R}/H_{c}(1-S*) at M = 0 of the magnetic hysteresis loop M(H) can be used to characterize SFD of the irreversible magnetization processes which correlate to the recording performance. Thus, (1-S*) is recommended as the most easily accessible and universally applicable figure of merit for SFD.
TL;DR: In this paper, a systematic study of magnetocrystalline anisotropy of R2Fe14B tetragonal compounds with various rare earth elements (R) has been carried out at room temperature by the pulse method.
Abstract: A systematic study of magnetocrystalline anisotropy of R2Fe14B tetragonal compounds with various rare‐earth elements (R) has been carried out at room temperature by the pulse method. The anisotropy fields of Y2Fe14B and Nd2Fe14B compounds are 3.1 and 12 MA/m, respectively. The maximum anisotropy field of 28 MA/m was observed in Tb2Fe14B compounds. The change in lattice parameters, saturation magnetization, and the Curie temperature with the rare‐earth elements of R2Fe14B compounds is also described.
TL;DR: In this article, the uniaxial anisotropy field H a of nominally single acicular particles was measured by three different methods, and the coercivity was also found.
Abstract: The uniaxial anisotropy field H a of nominally single acicular particles was measured by three different methods, and the coercivity was also found. A very dilute suspension was made in a viscous liquid, and a particle observed with the microscope. Various types of magnetic field were then applied, and the particle's change in orientation enabled H_{a}, H_{c} and/or H r to be determined. One method gave anomalously low values for H a , but it was possible to reconcile the results. The larger values lay in a range consistent with the chain-of-spheres and prolate ellipsoid models. There was a linear relationship between H a and H r (or H c ). The results suggested new reversal mechanisms.