Showing papers on "Saturation (magnetic) published in 1972"
TL;DR: In this paper, a new magnetic material which has the highest saturation magnetization at room temperature, 2050 G, among those of all the magnetic materials was attributed to Fe16N2, which has a bct structure, and the magnetic moment associated with Fe atoms of Fe 16N2 was deduced to be 3.0 μB.
Abstract: The change of the saturation magnetization of Fe films with the pressure of nitrogen during deposition ranging from 2 × 10−5 to 7 × 10−3 Torr has been investigated systematically. We found a new magnetic material which has the highest saturation magnetization at room temperature, 2050 G, among those of all the magnetic materials. This was attributed to Fe16N2, which has a bct structure, and the magnetic moment associated with Fe atoms of Fe16N2 was deduced to be 3.0 μB.
573 citations
TL;DR: In this article, a wide variety of transverse electromagnetic instabilities in plasmas with different sources and degrees of anisotropy are presented for the electron bi-Maxwellian, electron pinch, and ion-pinch experiments.
Abstract: Theory and simulation experiment are presented for a wide variety of transverse electromagnetic instabilities in plasmas with different sources and degrees of anisotropy. In each of the electron bi‐Maxwellian, electron‐pinch, and ion‐pinch experiments, the bulk response of the system during the initial stages of instability is in good agreement with the predictions of quasilinear theory. Furthermore, the two independent energy constants which derive from the fully nonlinear Vlasov‐Maxwell equations are found to remain constant to very good accuracy, even when the magnetic field energy reaches a substantial fraction of the total system energy. In each simulation experiment it is found that the magnetic energy saturates once the magnetic bounce frequency has increased to a value comparable to the linear growth rate prior to saturation, i.e., when ω¯B∼γ¯k. It is concluded that amplitude limitation for Weibel instabilities is a result of magnetic trapping for a broad range of system parameters. In many experi...
304 citations
304 citations
TL;DR: The attenuation of longitudinal 1 GHz sound waves, measured in vitreous silica down to 0.4 K, is strongly dependent on the acoustic amplitude and supports current theories on the thermal properties of amorphous substances at low temperatures as discussed by the authors.
88 citations
TL;DR: In this paper, the authors used X-ray diffraction and fluorescence analysis and determination ofJs-T curves revealed that the dominant ferromagnetic mineral extracted is probably a high Curie temperature form of titanomagnetite.
64 citations
TL;DR: In this paper, single crystals of Cr 3 Te 4 with the pseudo-NiAs type structure have been made by chemical transport method in order to investigate the anomaly below 80 K. But on contrary to his result, the easy axis of the moment is parallel to the c-axis in the whole ferromagnetic region and antiferromagnetic order appears only in the c -plane.
Abstract: Single crystals of Cr 3 Te 4 with the pseudo-NiAs type structure have been made by chemical transport method in order to investigate the anomaly below 80 K. The saturation moment at 4.2 K is equal to 1.79±0.03 µ B per Cr 1- x Te (x=0.25), and the Curie temperature is 316 K. The magnetization only in the direction to the a -axis shows the anomaly that the saturation field increases abruptly below 80 K, which corresponds to the Neel point proposed by Andresen. But on the contrary to his result, the easy axis of the moment is parallel to the c -axis in the whole ferromagnetic region and antiferromagnetic order appears only in the c -plane. By a spin echo method, two nuclear magnetic resonance absorption lines of Cr 53 -nuclei are observed at 45.3 and 57.5 MHz at 4.2 K. The resonance frequencies increase remarkably below 80 K. This fact may support subsidiarily the existence of the antiferromagnetic order below 80 K.
53 citations
TL;DR: The magnetic properties of rare-earth metals and a number of the alloy and compound systems formed with rare earths are discussed in this paper, where the results of bulk magnetic measurements and related transport phenomena and their bearing on theoretical studies are discussed.
Abstract: The magnetic properties of the rare-earth metals and a number of the alloy and compound systems formed with rare earths are discussed. Emphasis is placed on current experimental results of bulk magnetic measurements and related transport phenomena and their bearing on theoretical studies. Topics covered include exchange interactions, magnetization processes, crystal field effects and anisotropy, magnetostriction, spin structures and their field dependence, specific heat, optical effects, resistivity, magnetoresistivity, and other transport properties affected by the magnetic order. Examples are drawn from a number of material systems including ionic compounds, solid solution compounds (e.g., rare-earth magnetic semiconductors), intermetallic compounds (permanent magnet materials, etc.), and bubble domain materials in addition to the rare-earth elements and intra-rare-earth alloys. Tables are presented giving the spin structures, ordering temperatures, saturation and effective moments, and other properties of the elements and specific compounds.
48 citations
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TL;DR: The relationship between the magnetization and temperature in a high constant magnetic field for a temperature range between 5 K and 1100 K was examined for Apollo 11, 12 and 14 lunar materials as mentioned in this paper.
Abstract: The relationship between the magnetization and temperature in a high constant magnetic field for a temperature range between 5 K and 1100 K was examined for Apollo 11, 12 and 14 lunar materials. The average value of Curie point temperature is (768.2 ± 3.5)°C for the lunar igneous rocks and (762.5 ± 3.4)°C for the lunar fines and breccias. A tentative conclusion about the ferromagnetic substance in the lunar materials would be that Fe is absolutely dominant with a slight association of Ni and Co, and probably Si also, in the lunar native irons. The antiferromagnetic phase of ilmenite and the paramagnetic phase of pyroxenes are considerably abundant in all lunar materials. However, a discrepancy of observed magnetization from a simulated value based on known magnetic elements for the temperature range between 10 and 40 K suggests that pyroxene phase represented by (M
x
Fe1-x
) SiO3 (whereM = Ca2+, Mg2+, etc and 0 ≤x ≤1/4) also may behave antiferromagnetically. Magnetic hysteresis curves are obtained at 5 K and 300 K, and the viscous magnetic properties also are examined for a number of lunar materials. The superparamagnetically viscous magnetization has been experimentally proven as due to fine grains of metallic iron less than 200 A in mean diameter. The viscous magnetization is dominant in the lunar fines and breccias which is classified into Type II, while it is much smaller than the stable magnetic component in lunar igneous rocks (Type I). The superparamagnetically fine particles of metallic iron are mostly blocked at 5 K in temperature; thus coercive force (H
c
) and saturation remanent magnetization (I
R
) become much large at 5 K as compared with the corresponding values at 300 K. Strongly impact-metamorphosed parts of lunar breccias have an extremely stable NRM which could be attributed to TRM. NRM of the lunar igneous rocks and majority of breccias (or clastic rocks) are intermediately stable, but their stability is considerably higher than that of IRM of the same intensity. This result may imply that some mechanism which causes an appreciable magnitude of NRM and the higher stability, such as the shock effect, may take place on the lunar surface in addition to TRM mechanism for special cases. A particular igneous rock (Sample 14053) is found to have an unusually strong magnetism owing to a high content of metallic iron (about 1 weight percent), and its NRM amounts to 2 × 10−3 emu/g. The abundance of such highly magnetic rocks is not known as yet but it seems that the observed magnetic anomalies on the lunar surface could be related to such highly magnetized rock masses.
45 citations
40 citations
TL;DR: In this article, the collection of energetic ions of Kr and Tl in Si, Ge, GaP and GaAs has been studied as a function of ion dose and energy (up to 30 keV) using radioactive ions and assay techniques for measurement.
Abstract: The collection of energetic ions of Kr and Tl in Si, Ge, GaP and GaAs has been studied as a function of ion dose and energy (up to 30 keV) using radioactive ions and assay techniques for measurement. Build-up rates and saturation levels have been established for the various combinations of incident ion, incident energy and target material. The rates of build-up are monotonic and level off to a constant saturation concentration. No evidence was found for the oscillatory (factor ∼ 2) departure from saturation level observed by Tinsley and coworkers for 20 and 60 keV Bi in GaAs.
37 citations
TL;DR: In this article, the effect of lattice vibrations can explain the observed explicit temperature dependence of the hyperfine field at constant volume and that the deviation of the latter from the temperature dependence at constant pressure is well described by considering the thermal expansion also.
Abstract: The temperature dependences of the magnetization and of the hyperfine field in ferromagnetic metals such as Fe or Ni are different even after transformation to constant volume. It is suggested that the effect of lattice vibrations can explain the observed explicit temperature dependence of the hyperfine field at constant volume and that the deviation of the latter from the temperature dependence of the magnetization at constant pressure is well described by considering the thermal expansion also. Some applications of this model to related problems are discussed.
TL;DR: In this article, the authors proved that the output of a ring core sensor is directly proportional to the first time derivative of the product of dynamic permeability and magnetic intensity perturbation within the core caused by an external, uniform magnetic field.
Abstract: This article proves that the output from a ring core sensor is directly proportional to the first time derivative of the product of dynamic permeability and magnetic intensity perturbation within the core caused by an external, uniform magnetic field. (Dynamic permeability is defined to be the slope of the hysteresis loop at a given point in time.) Assuming that ellipsoidal shells can approximate the core, the demagnetization factor can be "estimated" in the first order to be proportional to the first power of the quantity tape thickness (or number of wraps) divided by the core diameter. The constant of proportionality is determined from laboratory data. When an additional scale adjustment is applied to the resulting sensor output formula, the computed output tracks laboratory data for a range of sensor geometries.
TL;DR: In this article, a non-collinear, three-axial, ground state configuration and stability conditions for such an ordering are found and an expression for the Curie temperature is obtained in the simplest molecular field approximation.
TL;DR: CeZn2 as mentioned in this paper exhibits a linear transverse wave moment alignment propagating along the c axis and polarized along the b axis direction and the saturation moment per Ce at 4.2°K is 1.6± 0.2 μB.
Abstract: CeZn2 and TbZn2 have the orthorhombic CeCu2‐type crystal structure. CeZn2 becomes a simple antiferromagnet below the Neel temperature of 7.5°K. The magnetic unit cell is of the same size as the chemical cell. All moments are aligned along the b axis and the saturation moment per Ce at 4.2°K is 1.6± 0.2 μB. In the range 60–75°K, TbZn2 exhibits a linear‐transverse‐wave moment alignment propagating along the c axis and polarized along the b axis direction. The wavelength of this static magnetization varies from 2.28 to 2.54 in units of c in this temperature range. The moment amplitude per Tb at 62.4°K is 6.91± 0.17 μB. At below 60°K, a first‐order magnetic transition takes place and the resulting antiferromagnetic structure has a magnetic unit cell twice the size of the chemical cell, the c axis being doubled. All moments are aligned along the b axis and the saturation moment per Tb at 4.2°K is 8.15± 0.10 μB. The magnetic structures of both CeZn2 and TbZn2 can be described as resulting from the stacking of f...
TL;DR: In this article, an increase in magnetization with an increase of the magnetic field well above technical saturation was measured at 4.2 K for single crystals of Fe-Al alloys in the directions of easy magnetization in the fields up to 55 kOe which is produced by a superconducting magnet, using an integrating digital voltmeter.
Abstract: An increase in magnetization with an increase of the magnetic field well above technical saturation were measured at 4.2 K for single crystals of Fe-Al alloys in the directions of easy magnetization in the fields up to 55 kOe which is produced by a superconducting magnet, using an integrating digital voltmeter. From the slope of the linear part of the magnetization curves in the high fields, the magnitudes of the high-field susceptibility were estimated to be 4.4, 5.0, 4.8, 6.1, 7.2, 53, 83 and 88×10 -4 emu/mole for 17.3, 20.1, 23.0, 24.9, 25.0, 27.1, 27.7 and 28.1 at.% Al-Fe, respectively. The observed behavior of the composition dependence of the high-field susceptibility can be interpreted on the basis of either the Pauli paramagnetism of 3d electrons, or a coexistence of ferromagnetic Fe 3 Al phase and antiferromagnetic FeAl phase.
TL;DR: In this paper, a simple thermodynamic model was proposed to predict the acceleration of the isothermal martensitic transformation of an alloy containing 26 % Ni and 2 % Mn, and the derived activation energy for embryo growth ( Δ W a ) and the shift in activation energy due to a field agree with those predicted on the basis of the Kaufman-Cohen model.
TL;DR: Magnetic properties of neptunium(V) oxalate, (NpO2)2C2O4·4H2O, were studied from 2.4 to 37.5°K with magnetic-susceptibility measurements using a vibrating-sample magnetometer at applied fields of 50−10 000 Oe; Mossbauer spectra of the 59.54−keV γ ray in 237Np were taken from 4.2 to 80°K.
Abstract: Magnetic properties of neptunium(V) oxalate, (NpO2)2C2O4·4H2O, were studied from 2.4 to 37.5°K with magnetic‐susceptibility measurements using a vibrating‐sample magnetometer at applied fields of 50–10 000 Oe; Mossbauer spectra of the 59.54−keV γ ray in 237Np were taken from 4.2 to 80°K. A metamagnetic transition was found at 11.6°K. Below 11.6°K the magnetization isotherms had the characteristic S shape of metamagnets. Below 8°K a pronounced hysteresis was observed as the field was reduced from saturation. At 3.15°K the remanent magnetization at 100 Oe was 96% of the saturation magnetization at 10 000 Oe, and 125 times greater than the magnetization in the low‐moment state. The Mossbauer spectra exhibited magnetic hyperfine splitting which was independent of temperature, with g0μnHeff = 10 cm/sec; splitting above the transition temperature is attributed to a long paramagnetic relaxation time.
TL;DR: In this article, a qualitative and quantitative theory of the MOS transistor in saturation is developed, taking into account the fact that the carrier concentration in the drain region is not negligible, with reference to the behavior in saturation, an injection level is defined.
Abstract: A qualitative and quantitative theory of the MOS transistor in saturation is developed, taking into account the fact that the carrier concentration in the drain region is not negligible. With reference to the behavior in saturation, an injection level is defined. This level is directly related to two parameters: the drain saturation field E DS and the effective depth of the drain region x D . A division of the current domain in low, medium, and high levels is proposed. For low injection levels (for which the saturation field is smaller than the critical field), an iterative procedure for the calculation of the drain saturation conductance is given. A method for determining the channel configuration is presented. Inconsistencies in the pinchoff concept are revealed by the calculation of this configuration and by the analysis of the validity domain of the equations based on gradual approximation.
Patent•
14 Feb 1972
TL;DR: A pole piece for magnetic thickness gauges is composed principally of a ferromagnetic material having magnetic saturation of less than 14,000 Gauss in order to increase the linearity of the scale readings when the gauge is measuring a very thin layer.
Abstract: A pole piece for magnetic thickness gauges is composed principally of a ferromagnetic material having magnetic saturation of less than 14,000 Gauss in order to increase the linearity of the scale readings when the gauge is measuring a very thin layer.
TL;DR: In this paper, a review of thin magnetic-film magnetometers used for magnetic field measurement is presented, and a summary of the magnetometer properties and their performance is provided, as well as a comparison of different types of magnetometers.
Abstract: Thin magnetic-film magnetometers used for magnetic-field measurement are reviewed and compared. A large variety of magnetic thin-film magnetometers have been constructed, and in some cases their properties are unique. A summary of thin-film magnetometers and their performance is provided.
TL;DR: In this article, the influence of various processing parameters, such as alloy composition, particle alignment, sintering density, and post-sintering heat treatment, on saturation, remanent magnetization, and coercive force are discussed.
Abstract: Over the last five years a family of cobalt‐rare earth permanent magnet alloys has evolved, of which Co–Sm and Co–Pr–Sm have the highest permanent magnet properties. A remarkable improvement of properties has been achieved in a relatively short period of time, for example the (BH)max energy product has increased by a factor of five, the B‐coercive force by a factor of three, and the remanent magnetization Br by a factor of two. These improvements in properties have resulted from improved processing techniques producing high density magnets with a high degree of alignment without loss of coercivity. In this review, the influence of various processing parameters; such as alloy composition, particle alignment, sintering density, and post sintering heat treatment; on saturation, remanent magnetization, and coercive force are discussed. Improvements in these magnetic properties achieved by careful control of processing will be stressed. In addition, a summary of the properties of the more promising Co–R alloys...
TL;DR: In this paper, a paramagnetic hyperfine structure (PHS) was observed in the Mossbauer spectrum of FeO4−2 diluted in concentrated NaOH in the presence of applied magnetic fields ranging from 0 to 2 kOe.
Abstract: Paramagnetic hyperfine structure (PHS) is observed in the Mossbauer spectrum of FeO4−2 diluted in concentrated NaOH in the presence of applied magnetic fields ranging from 0 to 2 kOe. The experimental results give an isotropic hyperfine interaction (A = − 1.17 mm/sec in the nuclear excited state), g=2.0 (isotropic) and no electric field gradient all of which are consistent with an eg2 configuration for the Fe6+ ion. Because of the dilution and low temperatures, the relaxation time among the electronic states is long enough for the 57Fe nucleus to couple to the magnetic moment in each state‐when there is a moment induced by the applied field. The saturation value of the hyperfine field is somewhat smaller than expected (175 kOe).
TL;DR: In this article, the remanent states after thermal and ac demagnetization (TD and ACD), dc and ac magnetization curves as well as the influence of the demagnetic temperature and magnetic field on the domain structure were investigated on a small specimen of aluminium substituted strontium hexaferrite single crystal.
Abstract: The remanent states after thermal and ac demagnetization (TD and ACD), dc and ac magnetization curves as well as the influence of the demagnetization temperature and magnetic field on the domain structure, were investigated on a small specimen of aluminium substituted strontium hexaferrite single crystal. It was found that the domain structure after ACD consists of a few domains only, while after TD it consists of a great number of domains with irregular Bloch walls. The TD states are very unstable and a transition to a similar ACD occurs in a field of about 50 Oe. These results were explained in terms of a simple model which takes into account the existence of magnetic inhomogeneities spread within the specimen.
TL;DR: In this article, a review of the magnetic properties required for cylindrical magnetic domains for memory and logic devices is presented. But magnetic properties for the above applications are quite different: large uniaxial anisotropies and saturation magnetizations are desirable properties for permanent magnet alloys and high coercivities are necessary properties for magnetic oxides.
Abstract: Two classes of magnetic materials have been technologically exploited during the last few years: 1. new permanent magnets which are replacing CoPt alloys for traveling wave tubes, and 2. magnetic oxides for use in new memory and logic devices which depend on the creation and propagation of cylindrical magnetic domains. These technological developments serve as additional examples of the interdisciplinary nature of materials science, the vigorous practice of which leads to new technology. The magnetic properties required for the above applications are quite different. Large uniaxial anisotropies and saturation magnetizations. and high coercivities are desirable properties for permanent magnets, while for memory and logic devices the materials must exhibit a moderately large anisotropy energy and low saturation magnetizations and coercivities. This review discusses new rare earth-cobalt permanent magnet alloys and cylindrical domain materials in terms of the above contrasting requirements.
TL;DR: In Ni C and Co C interstitial solid solutions, saturation magnetizations and high field susceptibilities decrease rapidly with increasing carbon content as discussed by the authors, and the two decreases are linear versus concentration: d μ d c = −3.6 μ B atom and dξ dc =−42×10 −6 e.m.u/gr/atom.
TL;DR: In this article, two single crystal samples, one in the shape of a small sphere and one in a disk, were studied with standard ESR spectrometers at 9.5 and 35 gigahertz.
TL;DR: In this paper, a method for deriving the saturation magnetization M S and domain wall energy, for thin crystals which support strip or bubble domains, by the comparison of measured initial slopes of magnetization curves and saturation fields with computed values, and the measurement of strip domain width.
TL;DR: In this article, the cavity oscillation conditions for coupled Stokes and anti-Stokes modes are investigated, with particular application to spin-flip Raman scattering in InSb.
TL;DR: An analysis based on field theory attempted in this paper brings out this aspect and also accounts satisfactorily for (i) Saturation, (ii) rotor wall thicknesses and (iii) end termination.
Abstract: Magnetic web of a hollow rotor induction machine leads to an improvement in performance. An analysis based on field theory attempted here brings out this aspect and also accounts satisfactorily for (i) Saturation, (ii) rotor wall thicknesses and (iii) end termination. Comparison with test results shows good agreement.