Dzyaloshinskii--Moriya interaction: How to measure its sign in weak ferromagnetics?

Three experimental techniques sensitive to the sign of the Dzyaloshinskii--Moriya interaction are discussed: neutron diffraction, Moessbauer gamma-ray diffraction, and resonant x-ray scattering. Classical examples of hematite (alpha-Fe2O3) and MnCO3 crystals are considered in detailComment: 5 pages, 1 figure; to be published in JETP Letter

Magnetic Resonance of the Intrinsic Defects of the Spin-Peierls Magnet CuGeO3

ESR of the pure monocrystals of CuGeO3 is studied in the frequency range 9-75 GHz and in the temperature interval 1.2-25 K. The splitting of the ESR line into several spectral components is observed below 5 K, in the temperature range where the magnetic susceptibility is suppressed by the spin-Peierls dimerization. The analysis of the magnetic resonance signals allows one to separate the signals of the S=1/2- and S=1 defects of the spin-Peierls phase. The value of g-factor of these signals is close to that of the Cu-ion. The additional line of the magnetic resonance is characterized by an anomalous value of the g-factor and by the threshold-like increase of the microwave susceptibility when the microwave power is increasing. The ESR signals are supposingly attributed to two types of the planar magnetic defects, arising at the boundaries of the domains of the spin-Peierls state with the different values of the phase of the dimerization.Comment: LATEX-text, 12 PS-figures, typos corrected, LATEX-style change

Magnetic structures and reorientation transitions in noncentrosymmetric uniaxial antiferromagnets

A phenomenological theory of magnetic states in noncentrosymmetric tetragonal antiferromagnets is developed, which has to include homogeneous and inhomogeneous terms (Lifshitz-invariants) derived from Dzyaloshinskii-Moriya couplings. Magnetic properties of this class of antiferromagnets with low crystal symmetry are discussed in relation to its first known members, the recently detected compounds Ba2CuGe2O7 and K2V3O8. Crystallographic symmetry and magnetic ordering in these systems allow the simultaneous occurrence of chiral inhomogeneous magnetic structures and weak ferromagnetism. New types of incommensurate magnetic structures are possible, namely, chiral helices with rotation of staggered magnetization and oscillations of the total magnetization. Field-induced reorientation transitions into modulated states have been studied and corresponding phase diagrams are constructed. Structures of magnetic defects (domain-walls and vortices) are discussed. In particular, vortices, i.e. localized non-singular line defects, are stabilized by the inhomogeneous Dzyaloshinskii-Moriya interactions in uniaxial noncentrosymmetric antiferromagnets.Comment: 18 pages RevTeX4, 13 figure

Briquetting of blast-furnace top dust

Ожогин, В. В. Брикетирование колошниковой пыли / В. В. Ожогин, О. Н. Кипчарская, Н. П. Акрамова // Вісник Приазовського державного технічного університету : зб. наукових праць / ПДТУ. – Маріуполь, 2010. – Вип. 20. – С. 39–43. – (Серія : Технічні науки).В статье исследована возможность и выявлены оптимальные условия брикетирования колошниковой пыли с целью её использования в металлургическом производстве.У статті досліджена можливість і виявлено оптимальні умови брикетування колошникового пилу з метою його використання в металургійному виробництві.The article deals with the description of optimal conditions of briquetting of top blast, with the aim of its subsequent application for blast furnace production

Effect of isotopic composition on the lattice parameter of germanium measured by x-ray backscattering

We have measured, by x-ray backscattering, the lattice constant of four highly enriched Ge isotopes: A=70, 73, 74, and 76 at temperatures ranging from 8 to 300 K. Comparing with Ge-70, values of Deltaa/a ranged from -10 to -46 p.p.m. A good quantitative agreement over the whole temperature range (8-300 K) was found with values calculated from a theory that takes into account the zero point motion and the anharmonicity of the lattice