Magnetic field effect on the photoluminescence of an Eu impurity during its aggregation in NaCl crystals

It is found that a magnetic field up to 20 T affects photoluminescence absorption spectra in NaCl:Eu crystals in the process of impurity aggregation into complexes. The spectral changes are irreversible and are observed after quenching the crystals at the early stages of the formation of small metastable complexes containing impurity-vacancy Eu²⁺-V dipoles. Emporal correlations revealed between the occurrence of the magnetoplastic effect and a change in the optical properties of the crystals in a magnetic field.     

Three-dimensional fully established flow of an ideal liquid around the blade systems of turbomachines

The present-day methods for the quasi-three-dimensional calculation of flow around the working organs of turbomachines were developed in [1, 2]. The most widely used in practice is the method of [2] (see, for example, [3, 4]), which, in a complete statement, proposes the solution of three known two-dimensional problems at the coordinate surfaces of a triorthogonal natural system of coordinate surfaces in the flow-through part of a turbomachine. A method is proposed below for the hydrodynamic calculation of blade systems directly in the three-dimensional region, based on solutions of the integral equations of the three-dimensional theory of a field, and not connected with any kind, of metric schematization of the flow of the liquid. Comparative analyses show that, with the use of an electronic computer, the present method and the method of [2] (in the complete statement) are practically equivalent.     

Influence of zeolite water on paramagnetic and ferromagnetic resonances in the Co2[Nb(CN)8] · 8H2O molecular magnet

The contributions of Co²⁺ and Nb⁴⁺ ions to the high-frequency dynamic magnetic susceptibility of the Co₂[Nb(CN)₈] · 8H₂O molecular magnet in the paramagnetic state at T > 12 K are separated. It is found that the ferromagnetic ordering, which leads to the reconstruction of the electron paramagnetic resonance spectrum into the ferromagnetic resonance spectrum, occurs at T < 12 K. The influence of zeolite water on the spectra of the paramagnetic and ferromagnetic resonances is found. Dehydration leads to a decrease in the time of the spin relaxation of the ferromagnetic system from 50 ps to 17 ps at T = 4 K and to the variation in the temperature dependences of the widths of the lines and g factors in the electron spin resonance spectra.     

Magnetomechanical effect in silicon (Cz-Si) surface layers

The mechanical properties of near-surface layers of Czochralski-grown silicon crystals Cz-n-Si(111) have been found to undergo changes in response to an external constant magnetic field (B ?? 0.1 T). A magnetically induced variation in the microhardness, Young??s modulus, and coefficient of plasticity of silicon crystals correlates with the change in the lattice parameter and internal stresses of the sample. The growth of an oxide film under exposure to a magnetic field plays the principal role in the magnetomechanical effect due to a decrease in the concentration of oxygen complexes in the near-surface layers of the sample. In microstructured silicon, where the surface is considerably more developed, the magnetic field induces more profound changes in the internal stresses as compared to single crystals.     

Analysis of Distribution of the Surface Magnetic-Field Gradient in (PrDy)(FeCo)B Rare-Earth Magnets

The main parameters of the domain structure of a (PrDy)(FeCo)B sintered permanent magnet are determined using magnetic force microscopy analysis of the magnetic-gradient distribution near the magnet surface. It is shown that the domain wall energy and width are not sensitive to the replacement of Nd with Pr and Dy in the studied RE-TM-B alloy. The anisotropy and exchange interaction constants are obtained. Two competitive processes of magnetization reversal (pinning and nucleation) are defined in sintered permanent magnets (PrDy)(FeCo)B.     

Magnetic properties of single crystals based on photochromic molecules of spiropyrans and chromium oxalates

Physics of the Solid State - The influence of UV irradiation on the effective magnetic moment and the Weiss temperature of single crystals based on photochromic molecules of spiropyrans and...     

“Magnetic Memory” in Plasticity of an Aluminum Alloy with Iron Inclusions

Physics of the Solid State - This article is devoted to the effect of a magnetic field of 0.7 T on the state of an aluminum alloy whose creep increases after exposing to a magnetic field,...     

Interaction of Magnetization Centers of Different Signs as the Cause of the Nonmonotonic Field Dependence of the Domain Wall Velocity in Synthetic Pt/Co/Ir/Co/Pt Ferrimagnets

The purpose of the work is to find the dependence of growth rate of magnetization centers of various types on their surrounding by other nucleation centers in a synthetic Pt/Co/Ir/Co/Pt ferrimagnet with perpendicular magnetic anisotropy. The following four types of nucleation centers exist in a sample with two ferromagnetic layers of different thicknesses: P+ centers correspond to the regions where the magnetizations of the thick and thin Co layers are directed along an applied field (↑↑); P– centers are the regions where the magnetizations of the layers are opposite to an applied field (↓↓); and AP+ and AP– centers correspond to the regions where the magnetizations of the thick and thin Co layers are opposite to each other and the total magnetic moment is along (↑↓) or opposite to (↓↑) an applied field, respectively. P– nucleation centers are found to be surrounded by AP+ regions in any field and exhibit a monotonic field dependence of their boundary. The field dependence of the growth rate of AP– nucleation centers is nonmonotonic since, as the field increases, they are surrounded by AP+ nucleation centers, AP+ and P– regions, and only P– nucleation centers in strong fields.     

Synthesis and properties of polyvinylpyrrolidone films containing the photomagnetic chromium (tris)oxalate complex

Uniform composites of polyvinylpyrrolidone with the paramagnetic chromium (tris)oxalate complex (C₂₃H₂₃N₂O⁺)₃Cr(C₂O₄)₃·11.56 H₂O and cation of quinoline spiropyran of the indo-line series were obtained for the first time. Their photochemical properties and static and superhigh-frequency dynamic magnetic characteristics were studied. The change in the ESR spectra under UV irradiation in films of polyvinylpyrrolidone containing photochromic paramagnetic was observed.