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Magnetic structure
About: Magnetic structure is a research topic. Over the lifetime, 10787 publications have been published within this topic receiving 207143 citations.
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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
TL;DR: YBaCo{sub 4}O{sub 7} belongs to a new class of geometrically frustrated magnets like the pyrochlores, in which Co spins occupy corners of tetrahedra as mentioned in this paper.
Abstract: YBaCo{sub 4}O{sub 7} belongs to a new class of geometrically frustrated magnets like the pyrochlores, in which Co spins occupy corners of tetrahedra. The structure can be viewed as an alternating stacking of Kagome and triangular layers. Exactly half of the triangular units of the Kagome plane are capped by Co ions to form columns running perpendicular to the Kagome sheets. Neutron powder diffraction reveals a broad temperature range of diffuse magnetic scattering, followed by long-range magnetic ordering below 110 K. A unique low-temperature magnetic structure simultaneously satisfies an S=0 arrangement in the uncapped triangular units and antiferromagnetic coupling along the columns. A spin reorientation above 30 K tracks the relative strengths of the in-plane and out-of-plane interactions.
105 citations
TL;DR: In this paper, the crystal structure of 2H perovskite BaMnO3 has been refined from neutron powder diffraction data collected at room temperature and 80 and 1.7 K.
Abstract: The crystal structure of the 2H perovskite BaMnO3 has been refined from neutron powder diffraction data collected at room temperature and 80 and 1.7 K. The structure consists of chains of face-sharing MnO6 octahedra, separated by Ba2+ cations. At room temperature, a = 5.6991(2), c = 4.8148(2) A, space group P63/mmc. At 80 K, a = 9.8467(1), c = 4.8075(1) A, space group P63cm. The structural phase transition introduces a displacement of neighboring chains and reduces the coordination number of Ba2+. Long-range antiferromagnetic ordering is apparent below TN = 59(2) K, with a magnetic moment of 1.31(5) μB per Mn4+ cation at 1.7 K. Neighboring spins within each chain are antiferromagnetically coupled and lie in a plane perpendicular to [001]. The spin directions associated with the chains at (1/3, 2/3, z) and (2/3, 1/3, z) are rotated by ±120° with respect to that of the chain at (0, 0, z).
105 citations
TL;DR: In this article, periodic density functional theory (DFT) calculations using plane-wave basis sets were performed in order to study the bulk of nickel ferrite NiFe2O4, and the local spin density approximation (LSDA) and the generalized gradient approximation (GGA) formalism were used, and appeared that the LSDA failed to describe the magnetic structure of this compound.
Abstract: Periodic density functional theory (DFT) calculations using plane-wave basis sets were performed in order to study the bulk of nickel ferrite NiFe2O4. The local spin density approximation (LSDA) and the generalized gradient approximation (GGA) formalism were used, and it appeared that the LSDA failed to describe the magnetic structure of this compound. However, the GGA formalism gave reliable results in good agreement with experimental data for the lattice parameters, the electronic properties and the bulk modulus. In addition, the calculated density of states of the metallic species d block as well as their local magnetic moments were correlated to the crystal-field theory. Then, a charge deformation map was computed and, as expected from the electronegativity scale, the electron excess is localized around oxygen atoms along the bond axes. The formation energies of metallic vacancies are in good agreement with the inverse spinel structure experimentally observed.
104 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