On Possible States of the Crystal Structure Preceding to a Phase Transition in Zn1 – xVxSe (0.01 ≤ x ≤ 0.10) Crystals

Physics of the Solid State - The systematic new formations observed in the reciprocal lattice of the cubic structural modification of a II–VI compound are characterized using a detailed...     

Magnetic structure of the Nd5Ge3 compound

Neutron diffraction measurements of the Nd₅Ge₃ intermetallic compound with a hexagonal structure (space group P6₃/mcm) have been performed at temperatures of ～10 and 293 K. The basis functions of irreducible representations of the space group D _6h ³ (P6₃/mcm), which are calculated as a result of the symmetry analysis of possible magnetic structures with the wave vector k = μb ₁, are used to facilitate the search for a real model of the magnetic structure of the compound.     

Effects of magnetic anisotropy and exchange in Tm2Fe17

Neutron diffraction experiments have been carried out to study the magnetocrystalline anisotropy of two (2b and 2d) Tm sublattices and four (4f, 6g, 12j, and 12k) Fe sublattices in ferrimagnetic compound Tm₂Fe₁₇ (space group P6₃/mmc). We have determined the temperature dependence of the magnitude and orientation of magnetization for each of the thulium and iron sublattices in the range (10?C300) K. A spontaneous rotation (at about 90 K) of the Tm and Fe sublattice magnetizations from the c-axis to the basal plane is accompanied by a drastic change in the magnetization magnitude, signifying a large magnetization anisotropy. Both Tm sublattices exhibit an easy-axis type of the magnetocrystalline anisotropy. The Fe sublattices manifest both the uniaxial and planar anisotropy types. The sublattice formed by Fe atoms at the 4f position reveals the largest planar anisotropy constant. The Fe atoms at the 12j position show a uniaxial anisotropy. We find that the inelastic neutron scattering spectra measured below and above the spin-reorientation transition are remarkably different.     

Magnetic structure of Er<Subscript>5</Subscript>Ge<Subscript>3</Subscript> at 4.2 K

A symmetry analysis of the possible magnetic structures of Er₅Ge₃ in the ground state is performed using the results of measurements of elastic magnetic neutron scattering at 4.2 K. It is shown that the minimum discrepancy factor R _m ≈9.5% corresponds to a modulated collinear magnetic structure in which the magnetic moments of erbium atoms are oriented along the a ₃ axis of the unit cell of the crystal structure and induce an antiferromagnetic longitudinal spin wave (AFLSW). The magnetic structure is characterized by the wave vector k=2π(0, 0, μ /a ₃) (where μ≈0.293) and the modulation period λ≈3.413a ₃. The magnetic ordering temperature T _N ≈38 K is determined from the temperature dependence of the intensity of magnetic reflections. __________ Translated from Fizika Tverdogo Tela, Vol. 45, No. 9, 2003, pp. 1653–1659. Original Russian Text Copyright ? 2003 by Vokhmyanin, Dorofeev.     

Magnetic structure of Er5Si3 at T ≥ 20 K

The symmetry analysis of magnetic structures of the Er₅Si₃ compound, possible at temperatures of 20 and 25 K, has been performed to interpret the experimental elastic neutron scattering data obtained at these temperatures. It was shown that the smallest dispersion factor R _m at these temperatures corresponds to the modulated magnetic structure in which the magnetic moments of Er atoms are directed along the a₃ axis of the unit cell and form an antiferromagnetic longitudinal spin wave characterized by the wave vector k = μb₃, where μ is approximately 0.264 and 0.274 at 20 and 25 K, respectively. The analysis of the temperature behavior of the magnetic reflection intensities demonstrated that the Er₅Si₃ compound is paramagnetic at 30 K.     

Magnetic phase transitions in TbNi<Subscript>5</Subscript> single crystal: Bulk properties and neutron diffraction studies

The angular dependence of the intensity of CK_α radiation measured from a film of oriented carbon nanotubes shows an increase in the yield of x-ray fluorescence along the growth direction of the nanotubes. The angular distribution of the intensity of scattered x rays is close in magnitude to the angular distribution of the directivity of nanotubes in the film that is determined by analyzing an electron-microscope image. To explain the propagation of radiation along the nanotubes, two mechanisms are proposed on the basis of reflection from inner walls of a tube (channeling) and an anomalous dispersion of CK_α photons in the carbon medium.