Showing papers on "Magnetic anisotropy published in 1972"
TL;DR: In this paper, the magnetic anisotropy of R2Co17 and R 2Co17−xTx compounds with R=Y, Ce, Pr, Nd, Th and T=Mn, Fe has been investigated.
Abstract: The magnetic anisotropy of R2Co17 and R2Co17−xTx compounds with R=Y, Ce, Pr, Nd, Th and T=Mn, Fe has been investigated. The directions of easy magnetization were determined by x‐ray studies on oriented powders. The several R2Co17 compounds, except for Ce2Co17, have an easy basal plane; the behavior of Ce2Co17 could not be clarified. Replacement of Co by Mn or Fe changes the easy magnetization direction from the basal plane to the c axis. Anisotropy fields were measured on magnetically aligned powders. The values for the anisotropy fields range between 12 and 24 kOe. Curie temperatures and saturation magnetization data for R2Co17−xTx compounds with T=Mn, Ru and R=Ho, Y are reported. The decrease of the magnetization with increasing x observed in the system Y2Co17−xTx is accounted for by assuming either a reduced Co moment or an antiparallel coupling of the T transition‐metal spin. Similar considerations hold for Ho2Co17−xTx ternaries.
88 citations
83 citations
TL;DR: In this article, the second derivative of the magnetization with respect to the magnetic field was studied for polycrystalline materials having uniaxial anisotropy, and evidence was given of a singular point located at $H={H}_{A}$, the anisotropic field.
Abstract: We studied the second derivative of the magnetization with respect to the magnetic field, $\frac{{d}^{2}M}{d{H}^{2}}$, for polycrystalline materials having uniaxial anisotropy. Evidence is given of a singular point located at $H={H}_{A}$, the anisotropy field. The observed sharp peak is associated with the infinity at $H={H}_{A}$ of the $\frac{{d}^{2}M}{d{H}^{2}}$ curve for the single crystal in the hard direction. The detection of singularities is proposed as a new, and sometimes unique, method of measuring magnetic anisotropy using polycrystalline samples.
58 citations
TL;DR: Magnetization and magnetic anisotropy measurements were made on single crystals of ErFe2 from 77°K to room temperature as discussed by the authors, and based upon these measurements the magnetic anomalous properties of the Laves phase RFe2 compounds (R = Tb, Dy, Ho and Tm) were predicted.
57 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 ordering and ordered magnetic moments in uranium monochalcogenides (US, USE and UTE) were investigated by neutron diffraction as mentioned in this paper, which revealed that these compounds are simple ferromagnets with the moments probably directed along the rhombohedral axis as found in a single crystal of US.
Abstract: The magnetic ordering and ordered magnetic moments in uranium monochalcogenides (US, USE and UTE) was investigated by neutron diffraction. These measurements were undertaken to clarify the conflicting evidence from magnetization measurements. Measurements on powdered samples of USe and UTe show that these compounds are simple ferromagnets with the moments probably directed along the rhombohedral axis as found in a single crystal of US. Compared with an ordered magnetic moment (at 4.2 K) of 1.70+0.03 mu B in US, the values 2.0+or-0.1 mu B and 2.2+or-0.1 mu B were found in USe and UTe, respectively. These values are significantly higher than the values measured by magnetization due to the large magnetic anisotropy associated with the rhombohedral distortion and also due to conduction electron polarization effects.
49 citations
TL;DR: In this paper, the pseudobinary systems are constituted of broad homogeneous regions of cubic and hexagonal Laves phase type and ordering tendencies on crystallographic sites between Al and the transition metal are studied in the hexagonal type.
Abstract: Both pseudobinary systems are constituted of broad homogeneous regions of cubic and hexagonal Laves phase type. Ordering tendencies on crystallographic sites between Al and the transition metal are studied in the hexagonal type. Magnetic investigations have been carried out only in the ordered regime. It is found that electron transfer from Al to the transition metals quenches their moments to the effect that they become nonmagnetic at high Al concentrations. At cryogenic temperatures the magnetization behavior of powdered specimens is complex in the intermediate region of concentration. Considerable magnetic hardness and anisotropy develops, and in DyFe2–DyAl2 pronounced spontaneous increases in magnetization with field occur as a result of the presence of highly energetic domain walls. The complex interplay of effects from disordered magnetic components, the crystalline electric field, and domain‐wall effects is discussed and compared with findings in related systems.
48 citations
40 citations
TL;DR: In this article, an interpolation scheme for hcp transition metals is developed as an extension of Mueller's method, and the band structures of fcc and hcp Co are calculated by KKR with a suitable potential.
Abstract: An interpolation scheme for hcp transition metals is developed as an extension of Mueller's method. The band structures of fcc and hcp Co are calculated by KKR with a suitable potential, and the parameters in the interpolation scheme are determined so as to give the best fit. It is found that Mueller's scheme is well applicable to hcp Co. The density-of-states of Co is calculated and the topology of the Fermi surface of ferromagnetic Co is described. From the knowledge of the eigenvectors, the g -factor, the orbital magnetic moment and the coefficient of the magnetic anisotropy are calculated.
39 citations
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...
28 citations
Patent•
15 Dec 1972
TL;DR: A magnetoresistive device that is responsive to the value and direction of an external magnetic field generated near an edge thereof by a localized source by a corresponding variation of an electrical current applied to the device comprises at least one magnetoregressive layer of anisotropic material having its easy axis of magnetization orientated at an angle which lies between 0* and 90* and preferably approximately 45* with respect to the direction of flow of electrical current through the device.
Abstract: A magnetoresistive device responsive to the value and direction of an external magnetic field generated near an edge thereof by a localized source by a corresponding variation of an electrical current applied thereto comprises at least one magnetoresistive layer of anisotropic material having its easy axis of magnetization orientated at an angle which lies between 0* and 90* and preferably approximately 45* with respect to the direction of flow of electrical current through the device. The magnetoresistive layer is inserted between a pair of thicker high permeability magnetic layers when a more accurate localization of the source of the external magnetic field is required.
TL;DR: In this paper, the relative remanence and the remannence coercivity of acicular single domain cobalt-doped gamma ferric oxide particles have been measured as a function of temperature and cobalt concentration.
Abstract: The relative remanence and the remanence coercivity of acicular single domain cobalt-doped gamma ferric oxide particles have been measured as a function of temperature and cobalt concentration. In addition, the magnetocrystalline anisotropy field of the same material has been measured separately on cubic shaped particles in the temperature range of 140-420°K and over a concentration range of 1.5- 14.5 wt % Co. The relative remanence of the acicular particles increases strongly with decreasing temperature below a temperature T K at which the ratio of shape to magnetocrystalline anisotropy is 0.86. T K is independent of a partial alignment of the particles. At temperatures below T k , the remanence coercivity H R is found to follow reasonably well Neel's relation for crystalline anisotropy, H K = 0.32 H K .
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, the authors describe a method to eliminate the perturbation caused by the magnetization measurement by the classical flux integration technique by using a special compensated pick-up coil, using an integrating digital voltmeter as fluxmeter, the short term reproducibility reaches 2.10-6.
Abstract: Flux creep phenomenon occurs when a magnetic sample is displaced inside a superconducting solenoid. The magnetization measurement by the classical flux integration technique is disturbed by this phenomenon. We describe a method to eliminate this perturbation. At a fixed field, using a special compensated pick-up coil, the measurements, done at regular intervals, tend toward a final value proportional to the moment. Using an integrating digital voltmeter as fluxmeter, the short term reproducibility reaches 2 to 3.10-6. The apparatus is automatic. It allows measurements such as high field susceptibilities, law of approach to saturation, and anisotropic spontaneous magnetization.
TL;DR: In this paper, the magnetic anisotropy in a Heisenberg linear chain antiferromagnet has been investigated for CsMnCl 3 2H 2 O.
Abstract: Torque measurements were done for CsMnCl 3 2H 2 O in order to investigate the short range order effect on the magnetic anisotropy in a Heisenberg linear chain antiferromagnet. Above 10 K, the anisotropy in the paramagnetic susceptibility has a uniaxial symmetry referred to the direction of chains ( a -axis) corresponding to the essential intrachain spin correlations and, below this temperature, it becomes orthorhombic because of the evolution of three-dimensional magnetic correlations. The magnitude and temperature dependence of the axial anisotropy observed above 10 K could be explained by the classical linear chain model including only a small dipolar term as an anisotropy term.
TL;DR: In this article, the symmetry properties of the in-plane induced magnetic anisotropy in YIG epitaxially grown on gadolinium gallium garnet (GGG) substrates were studied.
Abstract: We have studied the symmetry properties of the in-plane induced magnetic anisotropy in {100} and {110} disks of single crystal YIG epitaxially grown on gadolinium gallium garnet (GGG) substrates. The ferromagnetic resonance (FMR) technique was used to determine the values of the cubic and induced magnetic anisotropies. The induced anisotropy is interpreted in terms of a magnetostrictive magnetic potential energy. We find that the effective field induced in the plane of the film is isotropic for {100} disks but for {110} disks the induced anisotropy is uniaxial within the plane.
TL;DR: In this paper, the energy of the system was assumed to be of the form of the easy axis of the antiferromagnets, and an external field was applied along this axis.
Abstract: Macroscopic aspects of the field induced phase transitions in two-sublattice uniaxial antiferromagnets are studied in the case of an external field applied along the easy axis. The energy of the system is assumed to be of the form
TL;DR: In this article, the magnetic recording heads made from nonlinear magnetic materials were used to calculate the magnetic fields for magnetic recording head made from ferrite magnetization curves and showed that as the head drive fields are increased, the resolution of the head deteriorates.
Abstract: Numerical methods are used to calculate the fields for magnetic recording heads made from nonlinear magnetic materials. The nonlinear model used in the study fits ferrite magnetization curves well and requires little computer time for evaluation. Results show that as the head drive fields are increased, the resolution of the head deteriorates.
TL;DR: In this paper, the magnetic properties of the crystal KMnF 3 were studied by the electron spin resonance method using several microwave frequencies, and the agreement between the experiment and the theory seems to be fairly good.
Abstract: The magnetic property of the crystal KMnF 3 was studied by the electron spin resonance method using several microwave frequencies. As the temperature was reduced from the Neel temperature of 88.3 K the resonance points shifted toward the low field. These lines, however, disappeared below 81.5 K and the other lines appeared. The field induced canted phase in the intermediate-temperature range is different from the low-temperature canted phase. Though the angular dependence of the spectra at 82.5 K observed by using the lowest frequency can be explained by the simple uniaxial antiferromagnetic resonance theory, the results at 24 GHz can not be explained by this theory. Tentatively, they are compared with the theory which assumes an antisymmetric exchange interaction with the Dzyaloshinsky-Moriya vector parallel to the easy axis. The agreement between the experiment and the theory seems to be fairly good.
TL;DR: In this article, it was shown that the tetragonal body-centered ErC2 becomes antiferromagnetic below 19 ± 2° K. The moment alignment is governed by several narrowly dispersed, incommensurate transverse magnetization waves.
Abstract: Neutron‐powder diffraction measurements show that the tetragonal body‐centered ErC2 becomes antiferromagnetic below 19 ± 2° K. The moment alignment is governed by several narrowly dispersed, incommensurate transverse magnetization waves. The major modulation waves propagate along the a axis and are polarized in the b axis direction. The magnetization wavelengths are 5.78, 5.4, 6.7, and 7.1 A, and the amplitudes are respectively 6.55, 2.2, 2.1, and 1.6 μB at 4.2°K. The ferromagnetic alignment in the plane perpendicular to a is slightly altered by several long‐periodicity modulations propagating along the b and c axes. A commensurate, antiferromagnetic wave also participates in the moment alignment below 10 ± 3° K. The commensurate wave is represented by setting the wavelength equal to the a spacing in the incommensurate wave mode. The commensurate moment is 2.5 μB at 4.2°K. The root‐mean‐square value of all the moment amplitudes is 7.8 μB at 4.2°K and increases to 7.9 μB at 2°K. These features are likely c...
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: The high-resolution optical spectra of TbP${\mathrm{O}}_{4}$ showed that there is antiferromagnetic ordering in the vicinity of 2.25 K, but that there must also be a Jahn-Teller distortion as mentioned in this paper.
Abstract: The high-resolution optical spectra of TbP${\mathrm{O}}_{4}$ show that there is antiferromagnetic ordering in the vicinity of 2.25 K, but that there must also be a Jahn-Teller distortion. Evidence that the distortion behavior couples strongly to the magnetic behavior is provided by optical experiments which show that (i) the distortion behavior must occur simultaneously with either magnetic ordering or the application of a large magnetic field and that (ii) the distortion is rotatable by an external magnetic field. It is possible to deduce from the distortion behavior the possible directions for the easy axis. A model is presented to explain the magnetic and distortion behavior. A variety of spectral features, including metamagnetic behavior, are observed but are not fully understood.
TL;DR: The temperature dependence of the direction of the easy axis of magnetization in the ferromagnetic compound Cr 1-x Te (x = 0.077, T c =342 K) is determined by single crystal magnetic and neutron diffraction measurements in the temperature range from 80 K to 350 K.
Abstract: The temperature dependence of the direction of the easy axis of magnetization in the ferromagnetic compound Cr 1- x Te ( x =0.077, T c =342 K) is determined by single crystal magnetic and neutron diffraction measurements in the temperature range from 80 K to 350 K. Below about 200 K the spin direction lies in the c -plane, but with the rise of temperature it stands up gradually towards the c -axis. At 293 K the spin lies in a direction intermediary between c -axis and c -plane. The result is not in accord with Hirone et al. 's according to which the anisotropy axis lies along the c -axis all the way from liquid helium temperature to room temperature. The discrepancy is attributed to the difference in x between their sample and ours.
TL;DR: In this article, the influence of the magnetization direction of the sources on the properties of the resulting magnetic anomalies is studied and applied to the Bay of Biscay and a discussion is presented of the importance of the presence of a pattern in the sources.
Abstract: Summary
This is a study of the influence of the magnetization direction of the sources on the properties of the resulting magnetic anomalies. In the case of two-dimensional surveys, the anisotropy which is caused by the non-verticality of the magnetization is detected by the calculation and study of second order properties of the anomaly function. The method is applied to the Bay of Biscay and a discussion is presented of the influence of the presence of a pattern in the sources. In the case of one-dimensional profiles across cylindrical structures, the second order properties do not depend on the dip of the magnetization and one needs to make use of the ‘shape factor”. This technique is demonstrated over a North Pacific ocean magnetic profile. The mathematical formalism used gives a clearer idea of the nature of the operation reduction to the pole.
TL;DR: In this paper, a binary Ising model is applied to magnetic alloys in order to estimate the average magnetic moment per spin at 0 K by computer simulation, where two kinds of spins are assumed to distribute randomly in an FCC lattice with the coupling parameters J 11 > 0, J 12 > 0 and J 22 < 0 between nearest neighboring spins.
Abstract: A binary Ising model is applied to magnetic alloys in order to estimate the average magnetic moment per spin at 0 K by computer simulation. Two kinds of spins are assumed to distribute randomly in an FCC lattice with the coupling parameters J 11 >0, J 12 >0 and J 22 <0 between nearest neighboring spins. It is shown that ferromagnetic long range order can exist if the concentration of the ferromagnetic ions exceeds a critical value which depends on the relative strengths of the couplings. In addition, the concentration dependence of the average magnetic moment is obtained and compared with experiments on Pd-Fe, Ni-Fe, Co-Fe and Ni-Mn alloys. Also discussed is the effect of the concentration-dependent atomic magnetic moment in the alloy system.
TL;DR: In this article, the principal refractive indices of some organic aromatic crystals of known structure have been measured and the principal molecular refractivities deduced from these and the molecular orientation.
Abstract: The principal refractive indices of some organic aromatic crystals of known structure have been measured and the principal molecular refractivities deduced from these and the molecular orientation. The substances investigated include aromatic compounds having three rings, two rings or one ring with different substituents. The results give a clear indication that strong magnetic anisotropy is always associated with strong optical anisotropy.
TL;DR: In this paper, the equilibrium positions of sublattice magnetizations and the resonance frequencies of the antiferromagnet having the Dzyaloshinsky-Moriya vector parallel with the easy axis are calculated for arbitrary directions of the applied field.
Abstract: The equilibrium positions of sublattice magnetizations and the resonance frequencies of the antiferromagnet having the Dzyaloshinsky-Moriya vector parallel with the easy axis are calculated for arbitrary directions of the applied field. The effect of the parallel susceptibility has been taken into account in the calculation. The results are compared with the experiments on KMnF 3 in the intermediate temperature range. Good agreement is obtained, supporting that the crystal has the Dzyaloshinsky-Moriya vector parallel with the easy axis.
TL;DR: In this article, the authors computed the ferromagnetic resonance absorption line in polycrystalline ferrites in the independent grain approximation taking account of the magnetic crystallographic and magnetostriction anisotropies.
Abstract: The ferromagnetic resonance absorption line is computed in polycrystalline ferrites in the “independent grain” approximation taking account of the magnetic crystallographic and magnetostriction anisotropies. The results obtained show that the influence of elastic stresses on the shape of the absorption line is analogous to the effect of the magnetic crystallographic anisotropy.