Showing papers on "Magnetic structure published in 1978"
TL;DR: In this article, a quasi-one-dimensional antiferromagnet of Ising-like spins of CsCoCl 3 was measured in the long range ordered region at 4.2 K and the critical exponent of the magnetization was found to be 0.34 around the Neel temperature 20.82 K.
Abstract: Neutron diffraction measurements were carried out on single crystals of CsCoCl 3 , a quasi-one-dimensional antiferromagnet of Ising-like spins, in the long range ordered region. The determined magnetic structure at 4.2 K is composed of antiferromagnetic stacking of ferrimagnetic c -plane with three sublattices as determined by Melamud et al. The spins are aligned along c -axis and were evaluated to be 3.11 µ B at 0 K by extrapolation. Unusual temperature dependence of magnetic reflection intensity was observed and interpreted as a partial disordering transition in which one of the three sublattices in a c -plane loses its magnetization above 13.5 K resulting in antiferromagnetic c -planes. This transition is discussed in connection with the antiferro-ferrimagnetic transition in the triangular Ising lattice. The critical exponent of the magnetization was found to be 0.34 around the Neel temperature 20.82 K.
163 citations
TL;DR: In this article, the magnetic moment of the compound Bi2Fe4O9 was found to be (4.95 ± 0.08) μB, compared with the value of 5 μB for the Fe3+ free ion.
Abstract: The compound Bi2Fe4O9 belongs to the space group Pbam ( D92h), with two formula units per unit cell. Neutron diffraction measurements showed that it is paramagnetic at room temperature and undergoes a transition to an antiferromagnetic state at TN = (264 ± 3) K in agreement with previous susceptibility and Mossbauer measurements. Analysis of the 80 K neutron diffraction pattern yielded a magnetic structure with the following features: (a) The basic translations ao, bo, co of the chemical lattice change into antitranslations in the magnetic lattice. (b) The spins are perpendicular to co. (c) The magnetic structure belongs to the PC2/m space group and is a basis vector to an irreducible space under the Pbam irreducible representations, in accord with Landau's theory of second-order phase transition. The position parameters of the Fe3+ ions in the unit cell were refined. The magnetic moment of the compound was found to be (4.95 ± 0.08) μB, compared with the value of 5 μB for the Fe3+ free ion. The temperature dependence of the { 131 } magnetic reflection peak intensity was measured and found to be in agreement with the sublattice magnetization predicted by the molecular field approximation.
104 citations
TL;DR: In this article, the analysis of the magnetic structures of type-II antiferromagnets (a FCC lattice with k = 1 2, 1 2, 1 2 1/2, 1 3, 1 1/ 2 ) is presented.
Abstract: The authors deal with the analysis of the equivalent magnetic structures of type-II antiferromagnets (a FCC lattice with k=(1/2, 1/2, 1/2)). This analysis is essentially based on symmetry considerations taking into account the symmetry of the group G(k) corresponding to a particular set of k-vectors and the symmetry group Gm of the ordered phase, which results from the direction of the Fourier component associated with each k-vector. Only a few magnetic structures are possible if two physical restrictions are imposed: the angle between ki and mki, is the same for each ki and each magnetic moment has the same value. It is concluded that MnO, NiO and FeO have a collinear magnetic structure whereas in CoO the collinear structure and the multiaxis Van Laar model are consistent with previous experiments. From neutron diffraction experiments on single crystals of CoO, under uniaxial stresses applied out of a tetragonal axis one can conclude that CoO is also a collinear antiferromagnet.
91 citations
TL;DR: In this article, the magnetic structure of neodymium metal was determined by combining the results of neutron diffraction studies on single crystals of the material with results of Landau symmetry arguments and renormalization-group theory.
Abstract: We have determined the magnetic structure of neodymium metal by combining the results of neutron diffraction studies on single crystals of neodymium with the results of Landau symmetry arguments and renormalization-group theory. The spins form a unique, two-dimensional, incommensurably modulated structure accompanied by a similarly modulated lattice distortion. The experimental value of the critical exponent $\ensuremath{\beta}=0.36\ifmmode\pm\else\textpm\fi{}0.02$ is in agreement with the theoretical prediction of $\ensuremath{\beta}\ensuremath{\sim}0.38$.
59 citations
TL;DR: In this article, powder neutron diffraction data on superconducting (Ts∼6 K) samples of ErMo6Se8 taken in the temperature range 0.05-2.0 K show that magnetic Bragg peaks develop at TM=1.1 K, in agreement with specific heat studies.
Abstract: Development of new ternary superconductors has led to materials which also show a strong tendency toward magnetic order when one of the constituent elements is a rare earth. Powder neutron diffraction data on superconducting (Ts∼6 K) samples of ErMo6Se8 taken in the temperature range 0.05–2.0 K show that magnetic Bragg peaks develop at TM=1.1 K, in agreement with specific heat studies. However, it is not possible to index these new reflections using a simple antiferromagnetic unit cell based on the ErMo6Se8 lattice. It is also not possible to index the magnetic reflections based on a single modulation vector, or with a modulation vector along a high symmetry direction including higher order harmonics. Thus either the long range magnetic order corresponds to a more complicated magnetic structure in the ErMo6Se8 lattice, or at least some of the peaks develop in impurity phases. These results are compared with the recent neutron data on the reentrant superconductors HoMo6Se8 and ErRh4B4, in which the develop...
36 citations
TL;DR: A canted structure has been observed in GdMg by neutron diffraction at 0.5 A. as discussed by the authors suggests for a cubic S-ion compound the existence of additional exchange interactions besides the Heisenberg coupling.
34 citations
33 citations
TL;DR: The best fit with the neutron diffraction data was obtained for a magnetic moment of 0.69 μ B on the tetragonal Fe [1] site and of 2.31 μB on the pyramidal Fe [2] site as mentioned in this paper.
31 citations
31 citations
TL;DR: The low-temperature magnetic structure of the hexagonal modification of FeGe has been determined by neutron diffraction methods as discussed by the authors, and the iron moment remains sensibly constant across the transition with a value somewhere in the range 1.60 and 1.74 mu B, depending on the particular form factor used to interpret the data.
Abstract: The low-temperature magnetic structure of the hexagonal modification of FeGe has been determined by neutron diffraction methods. Below a transition temperature of 30.5+or-0.5K, the iron moments cant away from the (001) direction to form a double-coned structure in which alternate antiferromagnetically aligned (001) sheets of iron atom moments make an angle of about 16 degrees to (001). The repeat period of the basal plane component of the moment is 0.009+or-0.001 AA-1. The iron moment remains sensibly constant across the transition with a value somewhere in the range 1.60 and 1.74 mu B, dependent on the particular form factor used to interpret the data. This moment value is consistent with that derived from neutron powder diffraction measurements made at 4.2K.
28 citations
TL;DR: The magnetic and electrical properties of polycrystalline samples of Na x VS 2 and Na x VSe 2 have been measured in this article, revealing a clear paramagnetic-an tiferro magnetic phase transition at about 50 K with a simultaneous first-order cooperative Jahn-Teller lattice distortion.
Abstract: The magnetic and electrical properties of polycrystalline samples of Na x VS 2 and Na x VSe 2 have been measured. For x = 1, compounds with semiconducting properties and with localized magnetic moments of the V 3+ (d 2 ) ions exist. These forms reveal a clear paramagnetic-an tiferro magnetic phase transition at about 50 K with a simultaneous first-order cooperative Jahn-Teller lattice distortion. The magnetic structure of NaVSe 2 , an essentially MnBr 2 type of magnetic ordering, has been determined by neutron diffraction. The forms with smaller Na contents are metallic; they show several anomalies in their magnetic and electrical behaviour as a function of temperature; these are considered to be due to charge density waves.
TL;DR: In this paper, a large series of cubic room-temperature magnetic oxides with the perovskite-like arrangement has been prepared, and the magnetic properties have been investigated on polycrystalline and single crystal samples.
TL;DR: In this paper, the magnetic form factor of Mn on high angle reflections, which is sensitive to the asphericity of 3 d -wave function, gives the unpaired electron population to be (0.89, 1.61, and 1.22) for (ψ xo, ψ x±, ψ u± ) orbitals, respectively.
Abstract: MnSb, which is a ferromagnet with NiAs type crystal structure, is investigated by using the polarized neutron diffraction technique. Precise measurements of the magnetic structure factors give the following results: (i) The magnetic form factor of Mn on high angle reflections, which is sensitive to the asphericity of 3 d -wave function, gives the unpaired electron population to be (0.89, 1.61, 1.22) for (ψ xo , ψ x± , ψ u± ) orbitals, respectively. These facts indicate that MnSb should be understood with a well overlapped 3 d -subbands model proposed in the band calculation on NiS rather than the broadened 3 d -level model proposed for MnAs(P) system. (ii) 3 d -electron number of Mn is found to be four in MnSb on the basis of the asphericity of the magnetic form factor in conformity with the band calculation. (iii) Sb is magnetically polarized with moment of about 0.2 µ B antiparallel to the total magnetization.
TL;DR: In this article, the Schrodinger equation is applied to the internal magnetic structure of Bloch walls to solve the boundary value problem on the two sides of the wail, and the solution is investigated further by calculation of the spin direction of a neutron in the wall.
Abstract: The internal magnetic structure of Bloch walls is idealized in a model with a conical helix of uniform pitch. The solution of the Schrodinger equation in this wall and the solution in the domains divided by the wall are applied to solve the boundary value problem on the two sides of the wail. Thence the transmission and reflectivity of the wall are determined. The solution is investigated further by calculation of the behaviour of the spin direction of a neutron in the wall. The result shows that the intensities of the direct and deflected beams depend on the path of the transition of the magnetization from the direction in the first domain to that in the second domain in the interior of the wall, i.e. on the wall thickness. It also indicates the possibility of an approximate method, the results of which are compared with the results of the exact method. Both methods described give results other than the Born approximation, until now the only possible method. It appears necessary for the elements of the method described here to be applied to magnetic scattering far from Laue reflections, i.e. in small-angle scattering.
TL;DR: In this article, a brief review of the physical properties of rare earth sesquicarbides is presented, where the saturation order moments per metal atom are 1.3, 3.0, and 9.5 Bohr magnetons, respectively.
TL;DR: In this article, a series of solid solutions with isomorphous replacement of chromium by manganese was found to be antiferromagnets in the whole range of composition, and a new magnetic structure was observed as the intermediate spin structure between Cr 2 As and Mn 2 AS structures.
Abstract: Cr 2 As and Mn 2 As, both being isomorphous with Cu 2 Sb type crystal structure, have been known as antiferromagnets with different magnetic structures. They are found to form a series of solid solutions with isomorphous replacement of chromium by manganese. Site preference of each kind of atom is observed that chromium occupies site-I of this crystals structure in preference to site-II. The solid solutions are found to be antiferromagnets in the whole range of composition. (Cr 1- x Mn x ) 2 As system is divided into three regions in terms of the magnetic structure. In the first region 0.0≤ x ≤0.24, the magnetic structure is the same as Cr 2 As. Second (intermediate) and third (manganese rich) regions are in the range of 0.25≤ x ≤1.0. In the third region, the magnetic ordering is of Mn 2 As type. A new magnetic structure, which is observed in the second region, is understood as the intermediate spin structure between Cr 2 As and Mn 2 AS structures.
TL;DR: In this article, the authors show that large reductions in the low-temperature resistivity of TmSe as increasing magnetic fields change the magnetic structure from multidomain to two-domain antiferromagnetism and, finally, to ferromagnetic alignment are consistent with a homogeneous intermediate valence state of the Tm ions.
TL;DR: The magnetic structure of Fe5SiB2 has been investigated using Mossbauer spectroscopy in this article, showing that the spin rotation takes place relatively abruptly, but at different temperatures in different parts of the sample thus indicating that the transition temperature is composition dependent.
Abstract: The magnetic structure of Fe5SiB2 has been investigated using Mossbauer spectroscopy In the temperature region 140 K-784 K the compound is found to be a simple ferromagnet with the spins parallel to the c-axis At lower temperatures the spins are located in or close to the ab-plane and there are indications that the pure ferromagnetic coupling is partly destroyed The spin rotation seems to take place relatively abruptly, but at different temperatures in different parts of the sample thus indicating that the transition temperature is composition dependent
TL;DR: In this article, a neutron diffraction study of Bi2Fe4O9 has revealed that this compound undergoes a transition from a paramagnetic to an antiferromagnetic state, which is characterized by the chemical lattice primitive translations are anti-translations of the magnetic lattice; the magnetic moments have the magnitude (4.95 ± 0.03) μB and are parallel to the a-b plane; and the magnetic space group is PC2/m.
TL;DR: In this article, measurements of the magnetization, electrical resistivity, transverse magnetoresistance and Hall effect have been made on the polycrystals of TbAg 1-x In x compounds.
Abstract: Measurements of the magnetization, electrical resistivity, transverse magnetoresistance and Hall effect have been made on the polycrystals of TbAg 1- x In x compounds. The Neel temperature T N has the minimum around x =0.3 where the magnetic structure changes from (ππ0) to (00π) mode. The ordinary Hall coefficient R 0 is positive for all the compounds and has the minimum around x =0.3. The spontaneous Hall coefficient R s is positive in silver rich region and decreases with increasing x and changes its sign at about x =0.1. The transverse magnetoresistance is proportional to square of the field. The results are discussed on the basis of the two band model. It is deduced that the number of conduction electrons is about 3×10 -4 per unit cell and that of holes is 0.71 for x =0 and 0.33 for x =0.5, decreasing with increasing x . The magnetic phase of this system is discussed on the basis of simple RKKY model.
01 Jan 1978
TL;DR: In this article, the wave vector describing the modulation cannot be formed by simple rational fractions of the reciprocal lattice vectors, i.e., the wave vectors describing the modulation are not formed by rational fractions.
Abstract: Many interesting physical systems undergo phase transformations to periodically ordered phases which are incommensurate with the underlying lattices, i.e. the wave vector describing the modulation cannot be formed by simple rational fractions of the reciprocal lattice vectors. The ordered structure may be a static charge density wave (CDW), a modulated lattice distortion, a spin density wave (SDW) or helical magnetic structure, or even a separate atomic lattice or “mass density wave” (MDW).
TL;DR: In this article, the magnetic properties of polycrystalline samples in the perovskite-like compound ThCu 3 Mn 4 O 12 (space group Im 3) have been investigated by neutron diffraction, magnetization and susceptibility measurements.
TL;DR: In this paper, the magnetic structure of NiS2-xSex has been investigated by Mossbauer effect of 57Fe doped NiS 2 -xSex and the magnetic moment of nickel rotates towards the (111) direction with increasing temperature in NiS16Se04.
Abstract: The magnetic structure of NiS2-xSex has been investigated by Mossbauer effect of 57Fe doped NiS2-xSex Mossbauer patterns of the non-collinear first-kind ordering of FCC have been observed both in metallic and semiconductive antiferromagnetic phases The local environment effect on the magnetic moments is weak in this system; the magnetic moments decrease uniformly at all nickel sites by selenium substitution With increasing x the magnetic moments decrease without any discontinuous change at the metal-semiconductor phase boundary The magnetic moment of nickel rotates towards the (111) direction with increasing temperature in NiS16Se04
TL;DR: In this article, the symmetry properties of the surface spin pinning parameter revealed experimentally in yttrium-iron garnet (YIG) films by spin-wave resonance measurements are interpreted on the basis of group-theoretical considerations.
TL;DR: In this article, the magnetic properties of GdMg3 have been found to depend very strongly on the Mg concentration, and the strong ferromagnetic properties are lost, giving way to antiferromagnetism.
Abstract: The magnetic properties of GdMg3 and TbMg3 have been found to depend very strongly on the Mg concentration. With increasing Mg concentration the strong ferromagnetism is lost, giving way to antiferromagnetism. For the magnesium rich compound TbMg3 the magnetic structure has been determined by neutron diffraction. Ferromagnetic (111)-planes are stacked antiferromagnetically in a direction perpendicular to these planes.
TL;DR: In this article, the diffraction maxima (001) and (100) of the Mn1.11Al0.89 alloy have been measured by the neutron powder diffraction method in the temperature range from 23 to 427 C.
TL;DR: In this article, the small-angle scattering behavior of neutrons in the refracting range is described and a method is given to determine the wall thickness, and the law of refraction in the case of magnetic birefringence for the optical axes in different domains inclined against each other is derived.
TL;DR: In this paper, the static susceptibility and zero field specific heat of powdered samples of Ln2ZrS5 (Ln = rare earth) have been carried out, and the effective exchange parameter J is derived from the experimental data, making use also of the details of the magnetic structure, which is determined from neutron diffraction experiments.
Abstract: Measurements of the static susceptibility and the zero field specific heat of powdered samples of Ln2ZrS5 (Ln = rare earth) have been carried out. Gd2ZrS5, Tb2ZrS5, Dy2ZrS5, Er2ZrS5 and Sm2ZrS5 show an antiferromagnetic ordering at 12.73, 9.27, 5.24, 2.5 and 4.5 K, respectively. The Tb-, Dy- and Er-compound have highly anisotropic magnetic properties which are described with an effective spin S = 1 2 Ising model. In spite of the complexity of the crystal structure, the effective exchange parameter J is derived from the experimental data, making use also of the details of the magnetic structure, which is determined from neutron diffraction experiments. An almost pure spin-spin interaction, projected into the crystal field ground state, may account for the observed phenomena.