Showing papers on "Saturation (magnetic) published in 1977"
TL;DR: In this paper, a new perpendicular magnetic recording system is proposed for high density recording, which uses the perpendicular magnetization mode which is basically free from the demagnetization in very high densities.
Abstract: By the analysis of the self-consistent magnetization and the direct observation of the remanent magnetization of a real tape, the authors discussed the obstacles which are, and will be, encountered in attaining a higher recording densities with the present magnetic recording system, which uses mainly a longitudinal magnetization mode. Then the properties of the three magnetization modes (longitudinal, circular, and perpendicular) are compared. The mode transformation is also discussed. Finally a new perpendicular magnetic recording system is proposed for high density recording. And some results of fundamental experiments are presented. The system uses the perpendicular magnetization mode which is basically free from the demagnetization in very high densities. Its realization mainly owes to the development of a perpendicular anisotropy film and perpendicular magnetic heads.
463 citations
TL;DR: In this paper, a quasi-linear analytical model is used to describe the nonlinear growth and saturation of tearing modes with mode number m⩾2 and the saturation amplitude is dependent on the form of the resistivity.
Abstract: A quasi‐linear analytical model is used to describe the nonlinear growth and saturation of tearing modes with mode number m⩾2. The saturation of the magnetic island growth is the quasi‐linear development of a single mode rather than a mode coupling process. The saturation amplitude, which is dependent on the form of the resistivity, is in good agreement with results obtained previously by numerically advancing the full set of nonlinear equations.
336 citations
TL;DR: The dielectric absorption of vitreous silica containing 1200 ppm of OH − -impurities has been measured at 10 GHz in the temperature range between 0.4 K and 8 K.
82 citations
TL;DR: In this paper, the saturation magnetostrictions of the Fe-Ni-base glasses vary as the squareaure of their respective saturation magnetizations, and the behavior in the FeCo-base and Co-containing glasses is strikingly different.
72 citations
TL;DR: In this article, the ternary diagram of the saturation magnetostriction and volume magnetostrictions in amorphous ribbons of Fe-Ni-Co system were measured from 77K to room temperature, by a three terminal capacitance method.
Abstract: The saturation magnetostriction and the volume magnetostriction in amorphous ribbons of Fe-Ni-Co system were measured from 77K to room temperature, by a three terminal capacitance method. The ternary diagram were given of the saturation magnetostriction and volume magnetostriction in (Fe x Co y Ni 1-x-y ) 78 Si 8 B 14 system. It was found that the largest saturation magnetostriction constant is 36×10-6for the composition Fe 65 Co 13 Si 8 B 14 at room temperature. The temperature dependence of the saturation magnetostriction and the volume magnetostriction in Fe-Ni-Co system were not a simple function of the temperature. The maximum value of volume magnetostriction δω/δH was observed for Fe 78 Si 8 B 14 to be 24×10-10Oe-1at room temperature.
48 citations
TL;DR: In this article, magnetic measurements on a CuMn alloy reveal that T m, the temperature of the susceptibility peak, is marked by a qualitative change in the magnetization-vs-field behavior.
48 citations
TL;DR: In this paper, the temperature and the field dependence of the law of approach to ferromagnetic saturation were investigated in amorphous Fe40Ni40P14B6-alloys.
43 citations
TL;DR: In this article, a pulsed NMR experiment is described which combines the principles of progressive saturation and selective population inversion, and a considerable sensitivity gain is obtained for the X resonances of an AX spin system with T1,A
42 citations
TL;DR: In this article, the second-order crystal field term of SmCo3B2 was calculated on the point charge crystal field model and was found to be considerably larger than the one of Sm in SmCo5 due to the unusual ratio of the lattice constants.
Abstract: Compounds RCo3B2 withR=Sm, Gd, and Er were prepared and identified structurally by X-ray diffraction. Magnetic properties of these materials were studied down to liquid He temperature. The materials order ferromagnetically (e.g.,T
c
for GdCo3B2 is 58 K). The magnitude of saturation moments indicates that Co is nonmagnetic in this environment. Bulk specimens of the compound SmCo3B2 show extraordinarily high coercive forces at 4.2 K (H
c
=50 kOe). The second-order crystal field term of Sm in this compound is calculated on the point charge crystal field model and is found to be considerably larger than the one of Sm in SmCo5. This is mainly due to the unusual ratio of the lattice constants.
39 citations
01 Nov 1977
TL;DR: In this paper, the steady-state solution of electromagnetic field problems in ferromagnetic materials is given, which is based on the differential diffusion equation assuming variable complex magnetic permeability.
Abstract: The steady-state solution of electromagnetic-field problems in ferromagnetic materials is given. The effects of magnetic saturation and hysteresis are included. The solution is based on the differential diffusion equation assuming variable complex magnetic permeability. A precise formula is given to calculate the total power losses due to eddy currents and hysteresis. Computed curves, together with measured curves, are given for active and reactive losses in mild steel. Good agreement is obtained between measured and computed values.
38 citations
TL;DR: In this article, two types of recording heads, the cores of which had different values of saturation flux density B s and almost the same values of effective permeability, were prepared and the recording characteristics with Ni-Co plated discs of varying coercivity H c (410-900 Oe) were examined.
Abstract: Two types of recording heads, the cores of which had different values of saturation flux density B s and almost the same values of effective permeability, were prepared and the recording characteristics with Ni-Co plated discs of varying coercivity H c (410-900 Oe) were examined. The materials of the head cores were a sputtered alloy (Fe-Si-Al) film ( B_{s} = 11 000 G) and a single crystalline Mn-Zn ferrite ( B_{s} = 3800 G). Results showed that the B s of the head core had to be about five times the H c of the media to produce the beneficial effects of high H c on short wavelength recording. From this point of view, the alloy film head has the advantage in high linear density recording because of its large B s . By using an experimental laminated alloy film head of narrow-track width (60 μm), the core of which had a large effective permeability (such as 115 at 40 MHz), sine-wave signals of short wavelength (smaller than 1.5 μm) and of high frequency (such as 37 MHz) were recorded on a high H c (900 Oe) plated disc and reproduced with the same head successfully.
01 Jan 1977
TL;DR: In this article, the soft magnetic properties of amorphous alloys are compared to those of Fe-Ni, Fe-Co and Fe-Si alloys and the design implications of these differences for power devices are not immediately clear.
Abstract: The soft magnetic material characteristics of iron-nickel, iron-cobalt, and iron-silicon are compared to a variety of amorphous alloys. The properties of the amorphous alloy toroids, as-wound, improve with decreasing magnetostriction as expected. However, even after annealing to completely stress-relieve the toroid, the properties still depend strongly on magnetostriction. To date, the amorphous alloys have somewhat higher losses and lower permeabilities than the same thickness Fe-Ni alloys have but the amorphous alloys are significantly superior to the Fe-Co and Fe-Si alloys. Applications of the amorphous alloys in small electronic devices appear to be justified where the design optimization can make use of (1) the lower cost expected from the amorphous alloys, (2) the higher induction of some of the amorphous alloys compared to the Fe-Ni alloys, or (3) their lower losses and higher permeabilities compared to the crystalline Fe-Co and Fe-Si alloys. The high saturation amorphous alloys of Fe-B as thin tapes have about one-fourth the losses of the best grain-oriented Fe-3.2% Si sheet steel measured with sine flux, but the saturation magnetization is 20% lower. The design implications of these differences for power devices is not immediately clear.
TL;DR: In this article, it was proved that the magnetic properties, especially the coercivity and the initial permeability of the film were due to the effect of magnetostriction and crystalline anisotropy.
Abstract: A 12 μm thick film with large saturation flux density, 11 000 G, and high effective permeability, such as 240 at 20 MHz, was prepared by using tetrode sputtering equipment from a ternary alloy that consisted of Si:10.5 wt.%, Al:5.6 wt.%, and Fe:bal. (Si rich Sendust alloy) at a target voltage of 1000 V DC . These were the best conditions for obtaining the minimum value of coercivity with the glass substrate in our experiments. The electric resistivity and Vickers hardness of the film became greater than the same qualities in bulk alloys. The increase in effective permeability at high frequencies, and the higher resistivity and hardness are believed to originate from the granular structure of the film. In this study, it was proved that the magnetic properties, especially the coercivity and the initial permeability of the film were due, not only to the effect of magnetostriction and crystalline anisotropy, but also to the effect of film structure.
TL;DR: In this article, anomalous changes in magnetic susceptibility, remanent moment and total moment were recorded continuously as a function of increasing compression, and they indicated that multidomain materials are better transducers of the seismomagnetic effect than single-domain materials.
TL;DR: In this article, the initial susceptibility and magnetization as a function of applied field and temperatures have been measured for the amorphous alloys RE 50 Ag 50 (RE=Gd, Tb, Dy, Ho, and Er).
Abstract: The initial susceptibility and magnetization as a function of applied field and temperatures have been measured for the amorphous alloys RE 50 Ag 50 (RE=Gd, Tb, Dy, Ho, and Er). These have been supplemented by measurement of the time dependence of magnetization. All these alloys exhibit a spontaneous magnetization at low temperatures. An order of magnitude for the magnetic anisotropy has been determined from the experimental data. The diverse phenomena responsible for magnetic ordering and the magnetic after-effect are analysed and discussed.
TL;DR: In this paper, the Raman spectra of single crystals of hexagonal CeCl3 have been investigated at T = 2K in external magnetic fields up to 6 T. The crystal field states of the 4f1(2F5/2)-configuration of Ce3+ show a linear Zeeman-splitting.
Abstract: The Raman spectra of single crystals of hexagonal CeCl3 have been investigated atT=2K in external magnetic fieldsB up to 6 T. The crystal field states of the 4f1(2F5/2)-configuration of Ce3+ show a linear Zeeman-splitting. Two degenerate phonon states (197 cm−1(E1g), 109 cm−1(E2g)) also split in the magnetic field. ForB parallel to the optic axisZ the field dependence of the splitting is similar to the behaviour reported earlier for Ce F3 and NdF3 (linear splitting at low fields, which is followed by a saturation at high fields). ForB⊥Z a splitting of the same phonons proportional toB2 is observed in CeCl3, which was not found in the other compounds. The linewidths of the electronic transitions and of the split phonon components are reduced with increasing magnetic fieldstrength.
TL;DR: In this article, the spin reduction of K2FeF5 has been investigated in terms of spin flop in a one-dimensional magnetic system and it has been shown that the spin-flop field is 1.4*10-3 for the ratio BA/BE of the anisotropy field to the exchange field.
Abstract: Mossbauer spectra of K2FeF5 obtained in a magnetic field applied parallel to the antiferromagnetic axis show that in a field of 3.7T the spins reorientate (flop) to become perpendicular to the applied field. The experimental value of the spin-flop field yields an approximate value of 1.4*10-3 for the ratio BA/BE of the anisotropy field to the exchange field. The applied field spectra also show a dependence of the hyperfine field on the applied field. This behaviour together with the anomalously low value of the saturation hyperfine field (41.0+or-0.5 T) and the temperature dependence of the hyperfine field are discussed in terms of the spin reduction, which results from a spin-wave treatment of an antiferromagnet. Calculations show that this spin reduction is enhanced in a one dimensional system. Comparison of the calculated and experimental values leads to an estimate of around 10-3 for the ratio J'/J of the interchain to the intrachain exchange constants, which shows that K2FeF5 provides a good approximation to a one dimensional magnetic system.
TL;DR: In this article, the crystal structure, magnetic transition point and saturation magnetic moment were determined for (Fe1-xMx)3P compounds with M=Cr, Mn, Co, Ni.
Abstract: The crystal structure, magnetic transition point and saturation magnetic moment were determined for (Fe1-xMx)3P compounds with M=Cr, Mn, Co, Ni. X-ray examination identified all the compounds as b.c.t., except Mn compounds with 0.3 0.3 could not be prepared. Antiferromagnetism was found in Mn compounds with x>0.3. The concentration dependence of lattice constants indicates that, in the range of small x, the substitution occurs preferentially at a specified site. The saturation moment at 4.2 K decreases almost linearly with increasing x, but with a different slope depending on the substituted elements. The result was discussed based on the assumption of the preferential substitution.
TL;DR: In this article, the χ(T) curves for 17 binary and 2 ternary ytterbium intermetallics have been found to have a common functional form with a characteristic temperature Tmax.
Abstract: Out of 17 binary and 2 ternary ytterbium intermetallics, in the five systems, YbGa2, YbCu2, YbAl2, YbAl3 and YbCuAl an intermediate valency was found. The χ(T) curves for these compounds have a common functional form with a characteristic temperature Tmax. No tendency to saturation is observed in the magnetization at 1.4 K in fields up to 330 kOe.
Patent•
15 Aug 1977
TL;DR: The glassy alloys consist essentially of about 13 to 73 atom percent cobalt, about 5 to 50 atom percent nickel, about 2 to 17 atom percent iron, and the balance essentially boron plus incidental impurities as mentioned in this paper.
Abstract: Glassy alloys containing cobalt, nickel and iron and evidencing near-zero magnetostriction and high saturation induction are disclosed. The glassy alloys consist essentially of about 13 to 73 atom percent cobalt, about 5 to 50 atom percent nickel, about 2 to 17 atom percent iron, with the proviso that the total of cobalt, nickel and iron is about 80 atom percent, and the balance essentially boron plus incidental impurities. The magnetostriction of the glassy alloys ranges from about +3×10 -6 to -3×10 -6 and the saturation induction is at least about 8 kGauss.
TL;DR: In this article, a consistent interpretation within the spin Hamiltonian formalism is possible if the crystal field parameters are admitted some random variation from one iron ion to another in the glass matrix.
TL;DR: In this paper, the effects of the variation of magnetic grain size on the magnetic properties of rocks have been studied throughout a reversely magnetized basaltic dyke with concentric cooling zones.
TL;DR: In this article, drive field characteristics during rapid (0.1-7 T mu s-1) constant-voltage magnetization reversals in HCR tapes of thickness 6, 12 and 25 mu m are reported.
Abstract: Drive field characteristics during rapid (0.1-7 T mu s-1) constant-voltage magnetization reversals in HCR tapes of thickness 6, 12 and 25 mu m are reported. Four stages may be distinguished: (i) a sharp rise of instrumental origin, (ii) a fairly level 'step', (iii) a roughly linear rise that accords well with the 'saturation-wave' (SW) model, and (iv) a steep rise before saturation. Magneto-optic observation shows that the surface magnetization practically saturates at the step to SW transition. This occurs relatively earlier the faster the switch and the thicker the tape. Two models for the step stage are considered. In the first (BDM) bar domains are separated by walls that span the tape thickness. The second (SDM) consists of surface domains of roughly semi-elliptical cross-section. Both assume a detailed balance between domain wall surface tension and magnetic field pressure.
TL;DR: In this article, the authors studied the magnetic reversals of quasibinary solvices with R(Co 1-x Ni x ) 5, where R = Y, La, Ce, Sm, and Gd.
Abstract: The basic properties (saturation moments, Curie temperatures, anisotropy constants) and magnetic reversal processes have been studied systematically on the bulk single crystals of quasibinary solid solutions R(Co 1-x Ni x ) 5 , where R = Y, La, Ce, Sm, and Gd. The magnetic reversals have been studied also on the single crystals of similar compounds with R = Nd, Dy, and Er. The general property of all studied systems is a very high coercive force H c connected with domain wall pinning in compounds of quasibinary region. The H c (x) dependenses for all systems are similar qualitatively. There exists a maximum of H c in region x = 0.6 - 0.7 for compounds with trivalent R, and in region x = 0.3 - 0.4 for compounds with tetravalent R. The single exception is the Gd system, where H c has rather low values for all x. The explanation is suggested for H c (x) dependence in which the compositional heterogeneities are considered as the main reason of domain wall pinning in the quasibinary compounds. These heterogeneities are always present as a result of statistical nature of Ni substitutions for Co.
TL;DR: In this paper, the authors investigated the intensity, relative stability and directional behavior in AF demagnetization of the natural (NRM), saturation (IRMS), thermal (TRM) and spontaneous (SM) magnetization in several iron meteorites spanning the compositional-structural spectrum.
Abstract: Iron meteorites are macroscopic single-crystals of Ni-Fe alloy (ave. 10% Ni), segregated into strongly ferro-magnetic (a) and weakly magnetic phases, inter- grown in the octahedral system. Given their probable origin as molten metal cores or pods, slowly cooled (at rates ~ 1–100°C/my) in asteroidal bodies, they seem ideally suited to record ancient magnetic fields as thermal (TRM) or thermochemical (TCRM) remanent magnetization. To test this hypothesis, we investigated the intensity, relative stability and directional behavior in AF demagnetization of the natural (NRM), saturation (IRMS), thermal (TRM) and spontaneous (SM) magnetization in several iron meteorites spanning the compositional-structural spectrum.The main results are: 1) The remanence intensity and relative stability increase systematically from the coarser to the finer-grained classes. The latter are capable of carrying a stable paleoremanence. 2) The NRM coercivity spectra, which are considerably harder than laboratory TRM’s in the finest structured groups, gradually soften as grain-size coarsens. 3) All magnetization directions (NRM, TRM, SM) in octahedrites appear to be preferentially associated with the octahedral γ {111{ crystallographic planes on which α {110{ plates nucleated and grew, and/or aligned with their intersections. The finer the structure, the clearer the link of magnetization directions to ‘easy’ crystallographic planes and axes. 4) A direct comparison of NRM and TRM demagnetization curves yields paleointensities in the range 0.3–3 Oe. However, the similarity of SM’s (following zero-field cooling) to TRM’s. implies fictitious ambient field values of 2–5 Oe.
TL;DR: In this paper, the results of magnetization and transport measurements on amorphous Gd 80 Au 20, Gd 68 Ni 32 and Gd 67 Co 33 alloys over a temperature range of 1.8-300°K in fields up to 75 kOe were presented.
Abstract: We present the results of magnetization and transport measurements on amorphous Gd 80 Au 20 , Gd 68 Ni 32 and Gd 67 Co 33 alloys over a temperature range of 1.8-300°K in fields up to 75 kOe. These ferromagnetic alloys obtained by splat-cooling have Curie temperatures T c of 150, 125 and 175°K, respectively. The saturation moment per Gd atom extrapolated to 0°K is estimated to be 7± 0.1 μ B . The exchange integrals for Gd-Au and Gd-Ni are determined from the value of T c and from the temperature dependence of the saturation magnetization. The zero-field resistivity for Gd-Ni and Gd-Co exhibits maxima around T c . We present some preliminary results of magnetoresistivity measurements with applied field parallel and perpendicular to the foil plane. The anisotropy is in-plane for Gd-Co. For the Gd-Au and Gd-Ni alloys, there is no well-defined easy axis.
TL;DR: In this paper, a Hall probe was used to measure the magnetic field profile after applying localized stress to the center of a uniformly magnetized sample, and the effect of the stress on the pigment anisotropy was investigated.
Abstract: To estimate the extent to which a recording tape signal can be reduced during replay we have devised a rapid, sensitive, and simple testing technique. The method uses a Hall probe to measure the field profile after applying a localized stress to the center of a uniformly magnetized sample. We believe that this loss occurs when the pigment anisotropy is lowered by stressing particles, which have nonzero magnetostriction, in the presence of a demagnetizing field. The latter originates from particle interaction fields (H I ), self-demagnetizing fields from short magnetized segments, and fields from oppositely magnetized adjacent regions. The first effect is observed by stressing a uniformly magnetized sample in its remanent state; the second two are associated with frequency-dependent losses and can be simulated by applying stress with the sample located in a reverse field after initial saturation. Results indicate that H I is anisotropic and depends on the average angle between the magnetizing field and the long particle axis. When a reverse field is applied during stress, the maximum loss occurs at the coercive field where the loss is greater than the interaction field loss. All stress-induced losses vary logarithmically with the number of stress cycles, and scale with the magnitude of the applied stress and the absolute value of the saturation magnetostriction.
TL;DR: The five independent single-crystal elastic constants of hexagonal Gd-40%Y have been measured in the temperature range 4.2-300K and in magnetic fields of up to 7 T as mentioned in this paper.
Abstract: The five independent single-crystal elastic constants of hexagonal Gd-40%Y have been measured in the temperature range 4.2-300K and in magnetic fields of up to 7 T. This temperature and magnetic field range covers the different magnetic states of the material and has allowed the magnetic phase diagram to be constructed from the anomalies present in the elastic constants and associated ultrasonic attenuation. At low temperatures and low fields the material does not follow Dy and Tb-50%Ho in transforming from an antiferromagnetic to a ferromagnetic phase but exhibits a variety of more complicated magnetic structures.
TL;DR: In this paper, the magnetization and differential magnetic susceptibility of powdered samples of DyH3 have been measured at 4.2 K in applied magnetic fields ranging to 9 Teslas, with a maximum at T = 3.45 K, and an inflection point near 2.85 K.
TL;DR: The magnetic properties of the phosphide Fe2P were studied by Mossbauer spectroscopy and by magnetization measurements in external magnetic fields as discussed by the authors, and the wide dispersion of Curie temperature and saturation moments was discussed in terms of stoichiometry and crystallographic imperfections.
Abstract: The magnetic properties of the phosphide Fe2P are studied by Mossbauer spectroscopy and by magnetization measurements in external magnetic fields. The wide dispersion of Curie temperature and saturation moments previously observed is discussed in terms of stoichiometry and crystallographic imperfections. The Curie temperature is definitely fixed at (265 ± 2) K, and the saturation magnetic moment per Fe atom at (1.11 ± 0.02) μB.
Nous etudions les proprietes magnetiques du phosphure Fe2P par spectroscopie Mossbauer et par mesures d'aimantation dans un champ magnetique externe. Nous discutons la grande dispersion des temperatures de Curie et des moments a saturation precedemment observee, en termes de stoichiometrie et d'imperfections cristallines. Nous fixons la temperature de Curie a (265 ± 2) K et le moment magnetique a saturation par atome de Fe a (1,11 ± 0,02) μB.