Showing papers on "Magnetic structure published in 1972"
TL;DR: In this paper, a neutron diffraction study was carried out on SrFeO 3, and the results indicated that the magnetic structure is a helical one with the helicoid vector k ; k // and | k |=0.112 a *.
Abstract: A neutron diffraction study was carried out on SrFeO 3 . The results indicate that the magnetic structure is a helical one with the helicoid vector k ; k // and | k |=0.112 a * . The Fe 4+ magnetic moment is 2.7±0.4 µ B at liquid nitrogen temperature.
234 citations
TL;DR: SrCoO 2.5 with brownmillerite (4CaO·Fe 2 O 3 ·Al 2O 3 ) type structure is an antiferromagnet with the Neel temperature of 570 K.
Abstract: SrCoO 2.5 with brownmillerite (4CaO·Fe 2 O 3 ·Al 2 O 3 ) type structure is an antiferromagnet with the Neel temperature of 570 K. The magnetic structure as determined from a neutron diffraction study is of G-type and the Co 3+ magnetic moment is 3.3±0.5µ B at liquid nitrogen temperature.
111 citations
TL;DR: In this paper, a model for the magnetic structure of mictomagnetic alloys, which assumes a random spin-glass matrix with magnetic clusters, is discussed in the light of magnetic, ESR, and Mossbauer spectroscopic results.
Abstract: The observed magnetic behavior of mictomagnetic alloys is reviewed. A model for the magnetic structure of such alloys, which assumes a random spin-glass matrix with magnetic clusters, is discussed in the light of magnetic, ESR, and Mossbauer spectroscopic results.
110 citations
TL;DR: Samples of the system SrCo 1- x Fe x O 3- y (0≤ x ≤ 1, 0≤ y ≤ 0.5) have been prepared under varying oxygen pressure and temperature and their crystal-lographic and magnetic properties have been studied.
Abstract: Samples of the system SrCo 1- x Fe x O 3- y (0≤ x ≤1, 0≤ y ≤0.5) have been prepared under varying oxygen pressure and temperature and their crystal-lographic and magnetic properties have been studied. SrCoO 2.5 with brown-millerite type structure (high temperature phase) is an antiferromagnet with the Neel temperature of 570 K and the Co 3+ -O 2- -Co 3+ superexchange interaction is strongly antiferromagnetic. SrCoO 3 and SrCo 1- x Fe x O 3 ( x <0.9) with the cubic perovskite structure (high temperature phase) are ferromagnetic with the Curie temperature at about 200 K and the magnetization decreases rapidly with increasing x near SrFeO 3 whose magnetic structure is helical.
105 citations
83 citations
83 citations
TL;DR: In this article, the magnetic properties of Mn(OH)2 were investigated between 4.2 and 273 K. The magnetic superlattice reflections were indexed on the basis of a hexagonal unit cell with the dimensions a M = a (3), and cM = 2c where a = 3.322 A and c = 4.734 A are the dimensions of the chemical unit cell.
39 citations
TL;DR: In this article, three modifications of barium manganese oxide, BaMnO3(2H), BMo3(9R), and BMo 3(4H) were prepared using hydrothermal and high-pressure techniques.
36 citations
TL;DR: In this article, the magnetic structure and magnetic form factor of 154Sm have been determined based on neutron diffraction measurements on single crystals of 154sm using a nine layer stacking sequence along the c-axis with 2/3 of the sites having local hexagonal symmetry and 1/3 having local cubic symmetry.
Abstract: Neutron diffraction measurements on single crystals of 154Sm have been performed to determine the magnetic structure and magnetic form factor. The Sm crystal structure consists of a nine layer stacking sequence along the c‐axis with 2/3 of the sites having local hexagonal symmetry and 1/3 having local cubic symmetry. The hexagonal sites order at 106°K in an antiferromagnetic layer‐type structure with a stacking sequence (++0−−0…) along the c‐axis. The zeroes correspond to layers of cubic symmetry and the hexagonal moments are directed along the c‐axis. The magnetic cell is twice the chemical cell in the c‐direction. At 14°K, the cubic sites order in ferromagnetic layers parallel to (101) planes. Considering only the cubic sites, there is a (++−−) sequence along a direction perpendicular to these planes with moments parallel to the c‐axis. The magnetic cell for the cubic‐site structure is four times the chemical cell along both a‐ and c‐directions. No modification of the hexagonal‐site structure is observe...
35 citations
01 Jan 1972
TL;DR: In this paper, the authors review the magnetic structures of rare earth metals and of certain of their alloys and provide complementary structural data provided by the results of classical magnetizaton experiments.
Abstract: In this chapter we review the magnetic structures of the rare earth metals and of certain of their alloys. Much of this information has been obtained in the last ten years from neutron diffraction experiments. Complementary structural data have been provided by the results of classical magnetizaton experiments. A detailed survey of such data is given in Chapter 4. Ideally, both techniques should be, and indeed have been, used to obtain the maximum structural information.
32 citations
TL;DR: In this paper, it was observed that the magnetizations of Cr(I) and Cr(II) sublattices vanish at the same temperature, T N, due to the mis-indexing of lines which are actually due to Cr 2 O 3 contamination in the previous work.
Abstract: Cr 2 As is known as an antiferromagnet with the Neel temperature T N of 393 K. Its magnetic structure is determined by neutron diffraction by using single crystals as well as powdered samples. The magnetic structure obtained has such a symmetry that any isotropic exchange interaction vanishes between Cr(I) and Cr(II) sublattices, while dipole-dipole like interactions remain finite between them. Values of 0.40±0.08 µ B and 1.34±0.06 µ B are obtained for the magnetic moments of Cr(I) and Cr(II) respectively. Contrary to a previous study, it is observed that the magnetizations of Cr(I) and Cr(II) sublattices vanish at the same temperature, T N . This inconsistency is considered to come from the mis-indexing of lines which are actually due to Cr 2 O 3 contamination in the previous work.
Abstract: Elastic and quasi-elastic neutron scattering experiments on K 2 MnF 4 single crystal which is a typical two-dimensional antiferromagnet with Heisenberg exchange interaction, have been carried out. From the measurements of the temperature variation of magnetic Bragg intensities, existence of two types of the magnetic structure (K 2 NiF 4 -type and Ca 2 MnO 4 -type) with different Neel temperatures T N (42.37±0.02 K and 58.0±0.5 K, respectively) has been confirmed. The temperature variation of sublattice magnetization has been determined from the (1, 0, 0) magnetic Bragg inten-sity. The results can be expressed by a simple power law for 4.2 K< T < T N with β=0.188±0.01. After the quasi-elastic scattering measurements, two-dimensional spin correlation is found to be long-range over all the critical region. The diverging nature of the correlation length among intra-planar spins κ -1 at T N strongly suggests the two-dimensionality in this substance.
TL;DR: Saturation magnetization, X-ray and neutron diffraction measurements were made on ferromagnetic alloys in the compositions Ni2MnSb, Ni2mnSn, and Co2mnsSn as discussed by the authors.
Abstract: Saturation magnetization, X-ray and neutron diffraction measurements were made on ferromagnetic alloys in the compositions Ni2MnSb, Ni2MnSn, and Co2MnSn. The compounds investigated have a crystallo-chemical structure of L21 type, with a partial disorder among NiSb atoms in the case of Ni2MnSb and Ni(Co)‒Mn atoms in that of Ni2MnSn and Co2MnSn. It was also found that in Heusler alloys the Ni atoms have zero magnetic moment, but the Co atom has a magnetic moment different from zero. The values of the magnetic moment of Mn and Co atoms were also calculated at 80 °K and found to be μMn = 3.60 to 3.75 μB, μCo = 0.7 μB.
[Russian text ignored]
TL;DR: In this paper, the authors extended the analysis of Poincaré's analysis to three dimensions and used the theory of disclinations to describe the point singularities of nematic structures.
Abstract: 2014 The spins in a ferromagnet define a vector field. Their simplest line singularities are therefore disclinations of unit strength, and their point singularities are of the types analysed by Poincaré. A nematic liquid crystal is normally unpolarised. As a result, a vector placed along the nematic axis at a point may be carried continuously through « good » liquid crystal and return inverted. The simplest line singularities are therefore disclinations of half unit strength. A double circuit restores the vector to its original orientation. The director field thus has the character of the wave function of a spinor. The extension of this idea to three dimensions allows a preliminary description of the point singularities of nematic structures. LE JOURNAL DE PHYSIQUE TOME 33, NOVEMBRE-DÉCEMBRE 1972, Classification Physics Abstracts 02.00, 14.82, 16.40, 17 64 1. The singularities of ferromagnetic spin systems. We begin with an outline of Poincaré’s analysis of the singularities of vector fields in two and three dimensions. We then use this analysis and the theory of disclinations to consider the Bloch wall separating two ferromagnetic domains magnetised in opposite directions, the Néel line which separates two portions of the Bloch wall which have opposite helicities, and the Bloch point which separates two Néel lines which have opposite disclination strengths. A similar analysis is possible for Néel walls, Bloch lines and their singular points. 1.1 POINCARÉ’S ANALYSIS IN TWO DIMENSIONS. We consider a vector field (X, Y) in the plane (x, y). In Poincaré’s analysis [1], (X, Y) is the velocity of a particle situated at (x, y) ; in our analysis it is an unnormalised indicator of the direction of magnetisation at (x, y). We suppose that, in the neighbourhood of the origin, where all the coefficients are real. Unless Xo and Yo both vanish, the direction (X, Y) is well determined at the origin, which is then an ordinary point. The simplest singularities are those for which Xo = Yo = 0, while ai , bl, a2, b2 are not all zero. They are in general screw disclinations of strength ± 1. Disclinations of larger integral strengths may be produced by the confluence of these unit disclinations. We look for the regions in which the vector field (X, Y) is parallel or antiparallel to the radius vector (x, Y). This requires which has non-zero solutions only if Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:019720033011-120108900
TL;DR: The magnetic properties of the ferromagnesian olivines, (Fe x Mg 1− x ) 2 SiO 4, have been studied between 4 and 300°K as mentioned in this paper.
TL;DR: A brief review of magnetic structures determined by neutron-diffraction techniques is presented with particular emphasis on developments in the past few years as discussed by the authors, including improvements in monochromators, the technique of neutron polarization analysis, and the profile-fitting method for analysis of neutron powder data.
Abstract: A brief review of magnetic structures determined by neutron-diffraction techniques is presented with particular emphasis on developments in the past few years. A number of recent experimental advances are described, including improvements in monochromators, the technique of neutron polarization analysis, and the profile-fitting method for analysis of neutron powder data. Theoretical aspects discussed are the application of magnetic symmetry and representation theory to the determination of magnetic structures. Magnetic structures of a wide range of materials of general interest are described. These include transition metal compounds with rock-salt, rutile, and hematite-type structures, spinels, perovskites, transition metals and alloys, rare-earth metals and alloys, actinide compounds, and compounds with one- and two-dimensional magnetic properties. Up-to-date data for about 200 of these compounds are summarized in tabular form.
TL;DR: In this paper, from powder neutron diffraction data a pair of collinear, enantiomorphic magnetic structures is derived, the magnetic space group of which is Ip41 22 or Ip 41 ‘22, respectively.
TL;DR: Some TbNi 1−x Cu x exhibit sinusoidal wave magnetic structures between 1.3 K and T N as discussed by the authors, where the ordered moment can be induced by exchange field which explains the stability of these structures down to 0 K.
TL;DR: In this paper, the magnetic properties of NiMnSb alloys were studied using neutron diffraction, X-ray diffraction and magnetometric techniques, and the distribution of the constituent atoms over the four sublattices was found and at 77 °K the magnetic structure of the alloys was determined.
Abstract: NiMnSb and CoMnSb alloys were studied using neutron diffraction, X-ray diffraction, and magnetometric techniques. The distribution of the constituent atoms over the four sublattices was found and at 77 °K the magnetic structure of the alloys was determined. In NiMnSb a magnetic moment of (3.85 ± 0.05) μB was found only on Mn atoms. In CoMnSb the moments were found on both transition metal atoms, (3.5 ± 0.1) μB on Mn and (0.3 ± 0.1) μB on Co. These moments are ferromagnetically coupled.
[Russian text Ignored].
TL;DR: In this paper, the DyNi compound exhibits narrow domain walls frozen by the anisotropy and its magnetic structure is isomorphous to that of HoNi belonging to the space group Pnm′a′.
TL;DR: In this paper, it was concluded that below the Neel temsperature of 392 K the intermetallic compound Mn3B4 becomes antiferromagnetic and at this stage only the Mn(2c) atoms are magnetic.
Abstract: From the neutron diffraction measurements it is concluded that below the Neel temsperature of 392 K the intermetallic compound Mn3B4 becomes antiferromagnetic. At this stage only the Mn(2c) atoms are magnetic. Below 226 K the Mn(4g) atoms also become magnetically ordered and deform the collinear antiferromagnetic structure to a spiral structure, with an angle of 157.5°, which at lower temperature gradually develops to a collinear antiferromagnetic structure again. The saturated magnetic moments are 2.92 μB for the Mn(2c) atoms and 0.44 μB for the Mn(4g) atoms.
[Russian Text Ignored].
TL;DR: In this paper, the specific heat of polycrystalline chromium in the temperature range 280-330 K was measured and the results were consistent with the occurrence of a first order transformation at about 311 K.
Abstract: Measurements have been made of the specific heat of polycrystalline chromium in the temperature range 280-330 K. The chromium was heat treated to minimize the effects of internal stress on the magnetic structure which have been described by Bacon and Cowlam. The results are consistent with the occurrence of a first order transformation at about 311 K. An estimate of the minimum total entropy of magnetic disorder has been made and is 70 mJ mol-1K-1. Relaxation effects have been observed.
TL;DR: The moment alignment is represented by the composite of two sinusoidal transverse waves both polarized in the b axis direction and propagating along the c axis but with a phase difference of 60.7 ± 1.2° as mentioned in this paper.
Abstract: Neutron powder diffraction measurements reveal that HoZn2, having the body‐centered orthorhombic crystal structure (CeCu2‐type), becomes an antiferromagnet below the Neel temperature of 13.5°K. The moment alignment is represented by the composite of two sinusoidal transverse waves both polarized in the b axis direction and propagating along the c axis but with the phase difference of 60.7 ± 1.2°. The propagation wavelength and amplitude at 4.2°K are, respectively, 2.27 in units of c and 9.4 ± 0.1 Bohr magnetons. Below 4°K, there are indications of the onset of another magnetic transition.
TL;DR: In this paper, the magnetic properties of ErOOH have been investigated and a magnetic moment of 7.14μB for Er3+ was determined from the neutron diffraction data.
Patent•
IBM1
TL;DR: A MULTILAYER MAGNETIC STRUCTURE COMPRISING AT LEAST FOUR ALTERNATING LAYERS of a MAGNETICAL MATERIAL and its OXIDE, UPON A SUBSTRATE, whereby a DESIRED COMBINATION of MAGNETICA PROPERTIES and WEAR RESISTANCE is ACHEIVED as mentioned in this paper.
Abstract: A MULTILAYER MAGNETIC STRUCTURE COMPRISING AT LEAST FOUR ALTERNATING LAYERS OF A MAGNETIC MATERIAL AND ITS OXIDE, UPON A SUBSTRATE, WHEREBY A DESIRED COMBINATION OF MAGNETIC PROPERTIES AND WEAR RESISTANCE IS ACHEIVED. A METHOD OF MAKING IS ALSO DISCLOSED. USES INCLUDE MAGNETIC DISK STORAGE APPLICATIONS.
TL;DR: Mossbauer et al. as mentioned in this paper proposed a postulated magnetic structure for Mn5Ge3 consisting of ferromagnetic alignment of spins within the two sublattices and parallel alignment between them.