Showing papers on "Magnetic structure published in 1979"
TL;DR: In this paper, a model for magnetic ordering around the defect clusters was proposed based on Catlow and Fender's model, showing that the number of spins lying in the (111) plane is consistent with Catlow's model.
Abstract: Neutron diffraction experiments have been carried out at room temperature and 42K on polycrystalline samples of FezO with z=0943, 0938 and 0929 At room temperature, the ratio of octahedral iron vacancies to tetrahedral iron interstitials is close to 3 and is therefore in agreement with the defect cluster proposed by Catlow and Fender (1975) Examination of the 42K data has led to a model for magnetic ordering around the clusters The interstitial cations and surrounding iron atoms are coupled by an antiferromagnetic exchange interaction The spins in this region lie in the (111) plane, not along (111) as in the defect-free regions The number of spins lying in the (111) plane is consistent with Catlow and Fender's model
95 citations
TL;DR: In this paper, the authors carried out very accurate neutron diffraction experiments on a polycrystalline sample, completed by experiments on single crystal and several magnetic reflections have been found which are characteristic of the propagation vector k↘=1/2+τ, 1/2−τ.
Abstract: The intermetallic Laves phase compound CeAl2 presents some unusual properties, which makes the exact nature of its ground state a matter of great interest. A first step towards an explanation would be the knowledge of any magnetic structure below 3.8 K (phase transition temperature). We have carried out very accurate neutron diffraction experiments on a polycrystalline sample, completed by experiments on a single crystal. Several magnetic reflections have been found which are characteristic of the propagation vector k↘=1/2+τ, 1/2−τ, 1/2. The corresponding magnetic structure consists of antiferromagnetic (110) planes in which the magnetic moments, lying along [111], are modulated according to a sine wave propagation along [110]. No variation of k↘ nor any tendency towards antiphase structure appear down to 0.4 K. This result is not coherent with the Kramers’ degeneracy of the Ce3+ ion because it implies a non magnetic level as a ground state. On the other hand previous polarized neutron experiments have shown an antiparallel coupling between the spins of the cerium and the conduction electrons. Both results, as well as other physical properties, agree with the existence of a singlet ground state associated with a strong d‐f coupling.
75 citations
TL;DR: In this paper, a multipole expansion around the atomic centers was used to analyze the spin distribution in di- (2, 2, 6, 6-tetramethyl-4-piperidinyl-1-oxyl)-suberate.
73 citations
TL;DR: In this article, a method of calculating the possible magnetic structures liable to arise from the paramagnetic phase of the crystal was proposed. But the method was based on phase transition symmetry theory and it was not suitable for the case of crystals with the symmetry group D63d.
71 citations
TL;DR: In this article, the magnetic properties of rare earth copper compounds were determined from the values of anisotropic paramagnetic Curie temperatures on the basis of the molecular field theory, which are in agreement with those evaluated from a point charge model.
Abstract: Measurements of magnetization and susceptibility have been made on single crystals of heavy rare earth copper compounds, RCu 2 . All these compounds show metamagnetism with a relative low critical field at 4.2 K. The paramagnetic Curie temperatures along each principal axis are anisotropic. The crystal field parameters V 2 0 and V 2 2 are determined from the values of anisotropic paramagnetic Curie temperatures on the basis of the molecular field theory. These values are in agreement with those evaluated from a point charge model. The neutron diffraction measurements on a TbCu 2 single crystal confirm the collinear magnetic structure.
70 citations
TL;DR: The magnetic structure of Mn4N is shown to be not exactly of ferrimagnetic collinear type as mentioned in this paper, and experiments using separately, non-polarised and polarised neutrons reveal the existence of a small triangular magnetic component on each of the Mn atoms that are at the centres of the faces of the cubes.
Abstract: The magnetic structure of Mn4N is shown to be not exactly of ferrimagnetic collinear type. Experiments using, separately, non-polarised and polarised neutrons reveal the existence of a small triangular magnetic component on each of the Mn atoms that are at the centres of the faces of the cubes.
39 citations
TL;DR: In this article, the magnetic structure of KFeS 2 was determined by the neutron diffraction method, and the iron moment of 2.43 ± 0.03 μ B lies in the a − c plane and is canted by 125.3 ± 1.7 degrees from a -axis at 4.2 K.
36 citations
TL;DR: In this article, the authors carried out neutron diffraction and susceptibility measurements on a CoNb 2 O 6 single crystal and found a screw structure with the y axis as screw axis and a screw angle of 133°.
34 citations
TL;DR: In this article, the first stage of magnetic structure decoding is described, which is aimed at determining the magnetic lattice of the crystal, using the information obtained from neutron diffraction patterns.
33 citations
TL;DR: In this paper, the magnetic structures with the wave vector K = 0 and those with K ≠ 0 are considered in detail and the basis functions of the irreducible representations are specified.
26 citations
TL;DR: In this paper, a combined x-ray and neutron diffraction study has shown that the so-called "triple-$\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$" structure is not the correct model of the magnetic structure of neodymium.
Abstract: A combined x-ray and neutron diffraction study has shown that the so-called "triple-$\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$" structure is not the correct model of the magnetic structure of neodymium. The x-ray data showed only the Bragg reflections originating from the double-hcp lattice. Hence, all additional reflections observed below ${T}_{N}$ by neutrons are of magnetic origin. Additional neutron-diffraction data have shown that the magnetic structure must be described by modulation wave vectors with components both parallel and perpendicular to the $〈100〉$ axes.
TL;DR: In this paper, it was shown by small-angle neutron scattering that the magnetic structure of Invar alloys in the ground state is characterized by the occurrence of static magnetic fluctuations on the scale of 10-12 A. These fluctuations are due to antiferromagnetic iron pair interactions.
TL;DR: In this article, measurements have been made of the heat capacity of three electrotransport-purified specimens of neodymium in the temperature range 2-10K and in zero magnetic field.
Abstract: Measurements have been made of the heat capacity of three electrotransport-purified specimens of neodymium in the temperature range 2-10K and in zero magnetic field. The authors observed more peaks in the heat capacity than have previously been reported, and by comparison of their work with published neutron diffraction data they can draw some conclusions about the magnetic structure of neodymium below 10K.
TL;DR: In this article, single-crystal measurements of the magnetic susceptibilities of VI 2 show an anomaly at a critical temperature of about 14 K. This anomaly can be attributed to a magnetic phase transition from a 120° structure to a collinear arrangement of the spins with a magnetic unit cell.
TL;DR: In this article, a computer program was developed for the determination of non-collinear and spiral structures, several models allowed by symmetry were compared with the experiment, and it turns out that the Dy-moments and the Crmoments as well order parallel in the a-b-plane.
TL;DR: In this paper, it was shown that certain satellites in the neutron diffraction pattern of Nd are not caused by a lattice distortion, but rather by a modulated moment component in the basal plane and perpendicular to b/sub 1/ε.
Abstract: Through neutron polarization-analysis experiments at 9.9 K, we have determined that certain satellites in the neutron diffraction pattern of Nd are not caused by a lattice distortion, but rather by a modulated moment component in the basal plane and perpendicular to b/sub 1/. The magnetic structure is thus even more complicated than hitherto proposed, and there is now no direct experimental evidence to support the ''triple-q'' model.
TL;DR: In this article, the authors developed the technique of determining the magnetic structures liable to occur in a crystal by analyzing the exchange Hamiltonian, based on Bertaut's idea that the exchange matrix eigenfunction corresponds to some magnetic structure.
TL;DR: In this paper, the magnetic moments obtained by integration and refinement are considerably reduced on both iron sites due to charge density transferred from intervening ligand ions, and a residual moment of uncancelled spin of (0.032 ± 0.004) μ B is observed on the oxygen ion.
TL;DR: The structure of the compound PrCo2Ge2 is of the BaAl4 type and the space group is I4/mmm and the lattice constants are a = 4.048 and c = 10.178 A as mentioned in this paper.
Abstract: The crystallographic structure of the compound PrCo2Ge2 is of the BaAl4 type. The space group is I4/mmm and the lattice constants are a = 4.048 and c = 10.178 A. A neutron diffraction study revealed a transition to a magnetically ordered state at TN ~ 27 K and six superlattice lines below TN. It is possible to index these lines according to a sinusoidal magnetic structure with a period τ-1 = 13.94 A along c. Observed intensities are consistent with ordering of the Pr sublattice with the magnetic axis along c.
TL;DR: Magnetic susceptibility and specific heat measurements and neutron diffraction experiments allow to locate Neel temperatures T N and also two types of transitions below T N. At T t of order T N/2 the susceptibility is maximum, and the magnetic structure is modified (for Se-rich compounds).
TL;DR: In this paper, the magnetic structure was found to be antiferromagnetic with the spins on the Mn atoms aligned normal to the [001] direction, and the moments of the Mn and Pt atoms were determined to be (4.0±0.4) μB and (0 4.4± 0.4] μB, respectively.
Abstract: Neutron‐diffraction patterns have been obtained for quenched and annealed samples of MnPt. The magnetic structure was found to be antiferromagnetic with the spins on the Mn atoms aligned normal to the [001] direction. The moments on the Mn and Pt atoms were determined to be (4.0±0.4) μB and (0.4±0.4) μB, respectively. These values for the moments are in good agreement with those obtained in earlier investigations. However, we do not find the previously claimed change in spin direction as a function of alloy composition.
TL;DR: In this paper, the non-magnetic ground state of the Al3Ce and Al11Ce3 compounds has been confirmed by neutron diffraction experiments on the multidetector of the ILL high flux reactor.
Patent•
28 Feb 1979TL;DR: In the absence of a magnetic field, a closed treatment of an anisotropic magnetic structure can be used to produce magnetic particles in an alloy by cooling such alloy in a controlled fashion from a first temperature at which the alloy is in a predominantly single phase state to a second temperature in a multiphase state.
Abstract: Magnetic alloys having an anisotropic magnetic structure produced by thermo-mechanical treatment in the absence of a magnetic field. The treatment calls for developing magnetic particles in an alloy by cooling such alloy in a controlled fashion from a first temperature at which the alloy is in a predominantly single phase state to a second temperature at which the alloy is in a multiphase state and deforming the alloy to result in cross-sectional area reduction of at least 30 percent (corresponding to elongation of magnetic particles by a factor of at least 1.7). Disclosed treatment leads to desirable magnetic properties, e.g., in Cu-Ni-Fe, Cu-Ni-Co, Fe-Al-Ni, Fe-Al-Ni-Co and Fe-Cr-Co alloys. For example, in the case of Fe-Cr-Co, alloy properties such as remanence-to-saturation squareness ratio in excess of 0.90 and maximum energy product in the range of 0.6-8.0 MGOe are achieved. Disclosed magnetic alloys are suitable for use in the manufacture of telephone ringers, relays, and electromagnetic transducers.
TL;DR: In this paper, a model of the magnetic structure of rare earth metal neodymium was derived by combining neutron diffraction data with the results of Landau symmetry arguments and renormalization group theory.
Abstract: The magnetic structure of the rare‐earth metal neodymium has remained a mystery for more than a decade. Recently, a magnetic structure which fits the experimental results has been reported [1]. Here it will be shown how the model was derived by combining neutron diffraction data with the results of Landau symmetry arguments and renormalization group theory. The spins form a fascinating two‐dimensional pattern with hexagonal symmetry, the ’’triple q’’ structure. The magnetic order is accompanied by a lattice distortion with a similar symmetry. Also, the results of a numerical study of simple model of a one‐dimensionally modulated system are reported [2]. The phase diagram includes multiple phase transitions between commensurate phases similar to those observed in CeSb. This model, and CeSb, are possible candidates for ’’the devil’s staircase’’ behavior where the periodicity jumps between an infinity of commensurate values.
TL;DR: In this article, a study in single crystals by specific heat, Mossbauer spectroscopy and magnetic susceptibility of the magnetic structure and kinetics and thermodynamics of formation of the ferrimagnetic component was made.
TL;DR: The magnetic structure and excitations of the linear chain hexagonal perovskite salt CsCrCl 3 have been studied by susceptibility, powder and single crystal neutron diffraction and coherent inelastic neutron scattering.
TL;DR: In this paper, the dominant mechanism governing the upper critical field H c2 in Y 1−x Gd x Rh 4 B 4 with x ≥ 0.1 is the magnetic exchange field of Gd spins.
TL;DR: In this article, the authors show that the decrease of magnetization at low temperature and the additional reflections in the neutron diffraction patterns are associated with the formation of noncollinear magnetic structure which is characterized by the antiferromagnetic component of the magnetic moments.
Abstract: On the basis of X-ray, magnetic and neutron diffraction measurements the range of solubility in the CrSxTe1−x (x = 0−0.2) system has been established and the magnetic phase diagram of the system has been plotted. The decrease of magnetization at low temperature and the additional reflections in the neutron diffraction patterns are associated with the formation of noncollinear magnetic structure which is characterized by the antiferromagnetic component of the magnetic moments. This component has the orthorhombic unit cell with , bM = a0, cM = c0. The character of the exchange interactions giving rise to this magnetic structure is discussed.
[Russian Text Ignored.]