Showing papers on "Saturation (magnetic) published in 1968"
TL;DR: In this article, the absolute saturation of Fe and Ni was determined by considering all contributions in the change of magnetization in high magnetic fields, i.e., internal demagnetizing fields, homogeneous rotations, and paramagnetic terms.
Abstract: Numerous measurements of saturation magnetization of Fe and Ni are reported. Saturation magnetization is determined by consideration of all contributions in the change of magnetization in high magnetic fields, i.e., internal demagnetizing fields, homogeneous rotations, and paramagnetic terms. The value found for the absolute saturation of iron is σ0,∞ = 221.71±0.08 emu/g, corresponding to M = 2.216 μB, in good agreement with previously accepted values. For Ni, the absolute saturation value obtained is σ0,∞ = 58.57±0.03 emu/g, corresponding to M = 0.616 μB, in good agreement with other previous data but 1.6% larger than the Weiss and Forrer's value of M = 0.606 μB.
261 citations
TL;DR: The magnetic and crystallographic properties of CaZn5-type intermetallic compounds of cobalt and rare-earth elements (including Th) have been investigated in this article.
Abstract: The magnetic and crystallographic properties of CaZn5‐type intermetallic compounds of cobalt and rare‐earth elements (including Th) have been investigated. Strong deviations from 1:5 stoichiometry are observed when the rare‐earth radius becomes relatively small. Both the saturation magnetizations (4πIs=2360–12 300 G) and the crystalline anisotropies (HA=25–210 kOe) depend on the rare‐earth component. The coercive forces have been studied as a function of the milling time. For SmCo5 and GdCo5IHc values larger than 13 000 Oe are observed. These high values are possibly due to small structural details in SmCo5 and GdCo5, if compared to the other compounds. First experiments for making permanent magnets by pressing fine powders of SmCo5 in a magnetic field have led to an energy product of 8.1×106 G Oe; the corresponding value for BHc is 5200 Oe.
158 citations
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
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TL;DR: Saturation magnetization was measured for alloy systems (FexNi1−x)92M8, where M=Cu, Co, Mn, Cr, and V, and also for Fe70(RexPt1 −x)30 at 4.2°K as discussed by the authors.
Abstract: Anomalous thermal expansion and its relation to magnetic properties are surveyed for various Invar alloys. Saturation magnetization was measured for alloy systems (FexNi1−x)92M8, where M=Cu, Co, Mn, Cr, and V, and also for Fe70(RexPt1−x)30 at 4.2°K. Sharp drop of the saturation moment occurs at the average electron concentration, N=8.13 to 8.52, for all the Invar alloys including the above‐mentioned alloy systems and N=8.21 to 8.52 for all the Fe–Ni base alloys. When, however, it was plotted against the electron concentration of the matrix surrounding less electropositive impurity atoms such as Mn, Cr, or V, all the alloy systems were found to exhibit a sharp drop of the moment in narrower concentration range of 8.48 to 8.60 for all the Fe–Ni base alloys. Saturation moment and a reversible susceptibility in the saturation range were also measured at room temperature for (110) [001] and (001) [110] rolled single crystals of the composition 29 at.% Ni–Fe. It was found that saturation moment was reduced from...
71 citations
TL;DR: In this article, it is shown that a magnetic field appears to be a powerful method of investigating the free energy characteristics of steels, through the relationship H(Jα −Jγ)/ΔT = ΔGγ→ α/T, [Ms], where (Jα) is the saturation magnetisation of the planes concerned.
53 citations
TL;DR: In this article, the magnetic properties of nine compounds represented by the formula Ln2Ni17 (Ln=Y or a lanthanide) are reported and the nickel moment is 0.27 μB, which is in very close agreement with 0.25 μB.
Abstract: Magnetic characteristics of nine compounds represented by the formula Ln2Ni17 (Ln=Y or a lanthanide) are reported. The Y, Sm, and Lu compounds are ferromagnetic; the others are ferrimagnetic. Curie temperatures range from 601° to 641°K. The nickel moment is 0.27 μB, which is in very close agreement with 0.25 μB, the value expected if all Ln valence electrons are transferred into the Ni 3d band. Magnetization of the Y2Ni17 and Lu2Ni17 compounds is lost in two stages as temperature is increased. Ferrimagnetism of heavy lanthanide compounds is indicated by the magnitude of their saturation moments and the form of the magnetization‐temperature curves. The magnetic coupling is the same as that observed in similar and related Ln–Co and Ln–Fe compounds, i.e., the Ln–Ni coupling is antiferromagnetic and ferromagnetic for heavy and light lanthanides, respectively. From the Curie temperature it is inferred that the Ni–Ni interaction is dominant. This is in contrast with the situation in Ni‐containing Laves and Hauc...
50 citations
TL;DR: In this article, the properties of the cubic Laves phases of the pseudo-binary alloys were investigated and the similarity to the behavior of alloys of elemental Co and Fe was pointed out.
Abstract: The hexagonal modifications of the Laves phases TiCr2, ZrCr2 and HfCr2 all exhibit Pauli paramagnetism with nearly the same susceptibility values (≈4 × 10≈4 e.m.u./mole). Measurements on the cubic modification of TiCr2 yield a slightly higher Pauli paramagnetic susceptibility (5 × 10−4 e.m.u./mole). The compounds TiCo2 and ZrCo2 form a single phase pseudo-binary system having the cubic Laves phase structure. The compounds exhibit Pauli paramagnetism with virtually constant susceptibility (1.44 to 1.53 × 10−3 e.m.u./mole) over the entire composition range. The YFe2YCo2 system is also single phase with the cubic Laves structure. These alloys are ferromagnetic over the entire composition range. As Co is substituted for Fe in YFe2 the saturation moment increases, passing through a maximum at the composition YFe1.4Co0.6. The striking similarity to the behavior of alloys of elemental Co and Fe is pointed out.
42 citations
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.
41 citations
TL;DR: The saturation magnetizations of cubic, iron-rich, solid solution alloys with copper, gold, germanium, tin and antimony have been measured between room temperature and 8 °K as mentioned in this paper.
Abstract: The saturation magnetizations of body-centred cubic, iron-rich, solid solution alloys with copper, gold, germanium, tin and antimony have been measured between room temperature and 8 °K. Mean atomic magnetic moments calculated from the data decrease linearly with solute concentration. The rates of decrease of moment with solute concentration for the solutes listed are -2·0, -1·1, -1·4, -1·0 and -1·0, respectively. Only iron-copper alloys come close to fitting the dilution model usually considered appropriate for iron alloys with non-transition element solutes. The other solutes apparently cause an increase in the average moment per iron atom. The exact mechanism by which this increase occurs is not clear.
35 citations
34 citations
TL;DR: In this article, a structure-dependent model has been developed to interpret the magnetomechanical effects associated with the response of a multidomain configuration to changes induced in the internal mechanical microstructure.
Abstract: Single crystals of natural magnetite have been subjected to extended elastic deformation. The irreversible magnetic effects investigated were the acquisition of remanence and reduction of saturation remanence by compression in a null or directed magnetic field. The magnitude of the remanent moment is dependent on a complementary combination of the extent of deformation and magnitude of the field. The strain-induced moment is much larger than the isothermal remanence acquired in the deformation field, and has a significantly greater relative stability. The transitory effects of interest under the influence of applied stress were increase of saturation remanence and changes in microscopic coercivity spectrum. A structure-dependent model has been developed to interpret the behaviour. The magnetomechanical effects may be associated with the response of a multidomain configuration to changes induced in the internal mechanical microstructure. These changes are caused by the stress, and are attributed t...
TL;DR: In this article, the saturation magnetization and the Mossbauer γ-absorption for Ga substituted ferrites having composition SrFe12−xGaxO19 have been measured.
Abstract: The saturation magnetizationσ and the Mossbauer γ-absorption for Ga substituted ferrites having composition SrFe12−xGaxO19 have been measured. The obtained data allowed us to choose between different hypotheses about the order of substitution of Fe3+ ions by Ga3+ ions in various iron sublattices. By applying a model of calculation which takes into account the influence of the substitution on the superexchange interactions between the nonsubstituted Fe3+ ions we have deduced a theoretical curve ofσ vs. x in agreement with the measuredσ values. A discrepancy between the experimental values ofσ and those deduced from our data on the hyperfine magnetic fields at the iron nuclei suggested the hypothesis of the existence of angles between the orientation of the Fe3+ magnetic moments. The Mossbauer spectra have also shown that in the Ga substituted strontium ferrites, the Fe3+ ions in 12K sublattice do not have the same magnetic moment. We given an interpretation of this fact.
TL;DR: In this article, it is suggested that the Fe moment is approximately 1.4 μB for x <⅓ and increases gradually for larger x to about 2 μB and this behavior may be explained by the presence of a shallow minimum in the density of states curve, sufficient to stabilize the moment for x.
Abstract: Measurements of the bulk magnetization have been made between 4.2°K and the Curie points for eleven compounds in the series DyxY1−xFe2. The Curie temperatures increase continuously through the series. The compounds near to x=0.3–0.4 exhibit temperature compensation points, and the saturation moments show that the equilibrium concentration occurs at x≃0.28. In addition, the coercivity increases rapidly in this region and has a value in excess of 10 kOe at x=0.35, T=4.2°K.If both the Fe and Dy moments remain constant or vary linearly through the series, the equilibrium concentration would occur at x≃0.35. Consideration of the results of these and other similar compounds indicates that the Fe moment varies nonlinearly with x. It is suggested that the Fe moment is approximately 1.4 μB for x<⅓ and increases gradually for larger x to about 2 μB. It is further proposed that this behavior may be explained by the presence of a shallow minimum in the density‐of‐states curve, sufficient to stabilize the moment for x...
TL;DR: In this article, it is shown that a second line ωqr that is regressively connected to ωpq is examined in a double resonance experiment, and a similar hole appears in an exactly corresponding region of the line profile, due to the disturbance of the spin population on the common level q. This has been called burning a hole in the line.
Abstract: In a high‐resolution nuclear magnetic resonance spectrum where the dominant line‐broadening influence is the spatial inhomogeneity of the magnetic field, it is possible to impose a sufficiently weak rf field (H2) on a given line ωpq such that saturation is localized in a restricted region of the sample volume. This has been called “burning a hole” in the line. When a second line ωqr that is regressively connected to ωpq is examined in a double resonance experiment, a similar hole appears in an exactly corresponding region of the line profile, due to the disturbance of the spin population on the common level q. This correlation, which arises from the intramolecular nature of the coupling, forms the basis of a technique for measuring frequency separations with a precision that is not primarily limited by the inhomogeneous linewidth. Experimental evidence suggests a reliability of ±1 mHz. The persistence of this effect down to rf levels as low as γH2 / 2π = 0.005 Hz distinguishes it from the well‐known coher...
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.
TL;DR: The saturation magnetizations of body-centred cubic solid-solution alloys of iron with titanium, molybdenum, tungsten, technetium and rhenium have been measured between room temperature and 8 °K.
Abstract: The saturation magnetizations of body-centred cubic solid-solution alloys of iron with titanium, molybdenum, tungsten, technetium and rhenium have been measured between room temperature and 8 °K. Mean atomic magnetic moments (μB/atom) calculated from the data decrease linearly with concentration between 2 and 10 at.% solute. The rates of decrease for the solutes listed above are -3392, -2105, -2044, -1405 and -1557 μB per unit of concentration respectively. When the data are plotted as a function of electron concentration they approximately superimpose on an extension of the Slater-Pauling curve. Combination of the magnetization results with the neutron diffraction measurements of Collins and Low shows that, while the solute atoms carry moments antiparallel to those on the iron atoms, the average moment per iron atom is either unchanged or increases slightly.
TL;DR: In this article, the conduction electron polarization in the paramagnetic state of dilute alloys of Co and Fe in a host matrix of platinum has been investigated by observing the nuclear magnetic resonance of the platinum host.
Abstract: We have performed an investigation of the conduction‐electron polarization in the paramagnetic state of dilute alloys of Co and Fe in a host matrix of platinum. This has been done by observing the nuclear magnetic resonance of the platinum host. Our measurements of Knight shift, linewidth, and relaxation time have been made as functions of impurity concentration (0.005–0.1 at. %), temperature (1.4°–300°K), and magnetic field (4–22 kG). We find that for small values of H/T the strength of the interaction between the conduction electrons and the local moments increases linearly with H/T. For higher values of H/T, but before saturation of the Brillouin function is expected to set in, we see a saturation of the linewidth with increasing 1/T, but not as a function of increasing H. We find the net shift of the center of gravity of the line is zero with respect to the Knight shift of pure platinum metal, and that the linewidth increases linearly with impurity concentration. These results provide evidence for int...
TL;DR: In this article, it was shown that TbAg2 having the tetragonal CaC2-type structure becomes antiferromagnetic below the Neel temperature of 35°K, which is identical to the commensurable magnetic structure of TbAu2 at temperatures below 42.5°K.
Abstract: Neutron‐diffraction measurements have revealed that TbAg2 having the tetragonal CaC2‐type structure becomes antiferromagnetic below the Neel temperature of 35°K. The ordered magnetic structure consists of the ferromagnetic sheets which are perpendicular to the a axis (face‐centered description), and the moment directions of the adjacent ferromagnetic sheets are opposite to one another. All moments are aligned in the direction of the c axis, and the saturation moment per Tb is 8.95 ± 0.05 Bohr magnetons which is essentially equal to the ordered moment of the free Tb3 + ion. This ordered structure is identical to the commensurable magnetic structure of TbAu2 at temperatures below 42.5°K, but the incommensurable transverse‐wavelike spin alignment of TbAu2 found in the 42.5°–55°K range was not detectable in TbAg2. Also, no detectable moment is observed for Ag in TbAg2.
TL;DR: In this paper, it was found that an absorber driven into saturation by a strong light pulse can amplify a weak light pulse simultaneously incident upon the medium, achieving gains as high as 20 cm−1.
Abstract: It has been found that an absorber driven into saturation by a strong light pulse can amplify a weak light pulse simultaneously incident upon the medium. Gains as high as 20 cm−1 have been observed. This effect is believed to be related to the ability of a saturable absorber to bring about mode locking in a laser cavity.
TL;DR: Mossbauer-effect measurements in the cubic Laves-phase pseudobinary magnetic alloys (ZrCo2)x(ZrFe2)1−x yield complex spectra as discussed by the authors.
Abstract: Mossbauer‐effect measurements in the cubic Laves‐phase pseudobinary magnetic alloys (ZrCo2)x(ZrFe2)1−x yield complex spectra. Magnetization curves on these alloys have been previously reported. ZrFe2, with a saturation moment at 4°K of about 1.6 μB per Fe atom and a Brillouin‐type magnetization curve, displays a Mossbauer spectrum consisting of two six‐line patterns, each with a hyperfine field of about 200 kOe. ZrFeCo has been reported to show only a quadrupole splitting at 78°K, although this is well below the Curie temperature. We have observed resolved hyperfine splitting in this composition at 78°K and at 4°K. The magnetization curves in (ZrCo2)x(ZrFe2)1−x for x=0.2, 0.4, 0.5, and 0.6 imply magnetic‐moment distributions. The Mossbauer spectra for these alloys show hyperfine field distributions that are strong functions of temperature over a wide range below the Curie temperatures. Discrete static distributions of hf fields may explain the spectra, but relaxation effects cannot be ruled out.
TL;DR: In this paper, the saturation value of the magnetization is in good agreement with the theoretical value for Mn2+(5 μB) and the moment before saturation does not vary linearly with the applied field.
Abstract: The magnetization measurements up to 420 kOe made on antiferromagnetic powder specimens of MnSO4 and MnSO4·H2O between 1.6° and 70°K have revealed saturation fields of 250 and 320 kOe, respectively. The saturation value of the magnetization is in good agreement with the theoretical value for Mn2+(5 μB). The moment before saturation does not vary linearly with the applied field. This fact could be explained by spin‐wave theory or by a biquadratic term in the exchange energy. The anisotropy and the exchange fields have also been estimated from our experiments. The susceptibility versus T plot has given the Neel temperature TN and the effective moment which corresponds to the S state of Mn2+.Specific heat measurements have also been accomplished on MnSO4. They confirm our value for TN (11.5°K) and show three other peaks below the Neel temperature, two of which could correspond to the transitions theoretically forseen for this magnetic structure (cycloidal cone spiral) by Solyom.
TL;DR: In this paper, it was shown that when the intermediate layer is palladium, the coupling results from diffusion of magnetic atoms into the palladium which makes it weakly ferromagnetic, and the main systems in which ferro-antiferromagnetic coupling is observed are Co-CoO, Ni-NiO, FeNi-FeNiMn.
Abstract: A coupling between the magnetization of two ferromagnetic films separated by a thin metallic layer has been observed. It is shown that when the intermediate layer is palladium the coupling results from diffusion of magnetic atoms into the palladium which makes it weakly ferromagnetic. The main systems in which ferro-antiferromagnetic coupling is observed are Co-CoO, Ni-NiO, FeNi-FeNiMn. In the latter case domain patterns and ripple are observed by electron microscopy.
TL;DR: In this article, general design equations have been derived which relate magnetic film parameters to memory operating currents and bit geometry, and the application of these equations is demonstrated in determining the magnetic specifications of a memory having 12 500 bit/in2.
Abstract: General design equations have been derived which relate magnetic film parameters to memory operating currents and bit geometry. The application of these equations is demonstrated in determining the magnetic specifications of a memory having 12 500 bit/in2. These characteristics were most easily realized in a composite magnetic film vacuum deposited sequentially from melts of 50-percent Co, 47-percent Ni, and 3-percent Fe and 83-percent Ni and 17-percent Fe. This is an excellent way of achieving characteristics which lie between those of any two layers taken separately as long as the total thickness is less than the exchange length, i.e., <2000A. Before etching and final processing, yields to magnetic specifications of 80 percent were achieved using these composite films.
Patent•
26 Jun 1968
TL;DR: In this article, the current and voltage applied to the object to be magnetized were adjusted to control the speed of magnetic saturation to more accurately sense the level of saturation in the demagnetizing steps.
Abstract: Apparatus for magnetizing and demagnetizing, including means for adjustable controlling the current and voltage applied to the object to be magnetized, for thereby controlling the speed of magnetic saturation to more accurately sense the level of saturation in the demagnetizing steps.
TL;DR: In this paper, an analysis of the anisotropy of the approach to saturation was carried out on cylindrical disks for different applied fields and several degress of deformation.
Abstract: Recent micromagnetic calculations have shown that magnetostrictive interactions of internal stresses with the magnetization produce an additional magnetocrystalline energy. In cubic crystals the additional anisotropy energy processes orthorhombic symmetry.The crystalline energy induced by plastic deformation in Ni single crystals (oriented for single glide) has been investigated through an analysis of the anisotropy of the approach to saturation. Measurements were carried out on cylindrical disks for different applied fields and several degress of deformation. In particular in the (111)‐plane the plastically deformed disks show a twofold and a fourfold symmetry axis in addition to the sixfold symmetry axis of the ideal crystal.Recent micromagnetic calculations have shown that magnetostrictive interactions of internal stresses with the magnetization produce an additional magnetocrystalline energy. In cubic crystals the additional anisotropy energy processes orthorhombic symmetry.The crystalline energy induced by plastic deformation in Ni single crystals (oriented for single glide) has been investigated through an analysis of the anisotropy of the approach to saturation. Measurements were carried out on cylindrical disks for different applied fields and several degress of deformation. In particular in the (111)‐plane the plastically deformed disks show a twofold and a fourfold symmetry axis in addition to the sixfold symmetry axis of the ideal crystal.
Patent•
19 Mar 1968TL;DR: In this article, the integrated intensities of the (hk 0) reflections from a single crystal at room temperature were measured and the corresponding nuclear scattering amplitudes derived and a comparison of these values with those calculated from Pauling's structure (B20) confirmed the two positional parameters and indicated a 5% deficiency of manganese in the sample.
Abstract: Recent measurements1 of the magnetic properties of the monosilicides of some 3d transition metals have shown that MnSi has a small ferromagnetic moment (≈0.4 μB/formula unit) at temperatures below 30°K. Neutron‐diffraction measurements have been made on both powder and single‐crystal specimens. The powder data show that there is no ordered antiferromagnetic component to the moment, so that the total moment is that derived from the saturation magnetization. This result may be compared with the value of 1.4 μB/Mn obtained1 from the Curie‐Weiss dependence of the susceptibility above 30°K.The integrated intensities of the (hk0) reflections from a single crystal at room temperature were measured and the corresponding nuclear scattering amplitudes derived. A comparison of these values with those calculated from Pauling's2 structure (B20) confirmed the two positional parameters and indicated a 5% deficiency of manganese in the sample. This latter observation can be correlated with the lower saturation magnetisat...
TL;DR: The present status of the theory of saturation magnetization of ferromagnetic thin films is reviewed in this paper, together with a comparison of the theoretical results with experimental data, and the effect of anisotropic magnetic fields on magnetization and Curie temperature is presented.
Abstract: The present status of the theory of saturation magnetization of ferromagnetic thin films is reviewed. The extensions of the Heisenberg trace method and the spin-wave method to the case of ferromagnetic thin films is fully discussed together with a comparison of the theoretical results with experimental data. The effect of anisotropic magnetic fields on magnetization and Curie temperature is presented, and the dependence of the magnetization and Curie temperature on film thickness is studied. Very recent progress and new results of the theory are stressed. The application of the Green function method to ferromagnetic thin films is also examined.