Magnetic configurations of hybrid ferromagnetic dot–superconductor systems

In-plane single domain and vortex magnetization configurations of the magnetic dot in the hybrid superconductor–ferromagnet system are considered. Single domain configuration energy shift due to the presence of superconductor is calculated. The change of the phase curve of the ferromagnetic dot magnetization due to the repulsion of the magnetic field by the superconductor is obtained. Up to the two-fold decrease of the ferromagnetic dot critical radius due to the presence of the superconductor is predicted.     

A conformally invariant limit of the critical lattice Ising model

A detailed analysis of an expansion in powers of 1/N (N1) for the Hamiltonian and the transfer-matrix of the Ising chain consisting ofN sites is presented. A special attention is paid to a term proportional to 1/N closely related to the theory of free massless Majorana fermions. An effective Hamiltonian isomorphic to that in conformally invariant theory is derived. The eigenvectors of the Ising Hamiltonian are classified in the framework of conformal algebra representation theory. The momentum and the energy for these states are expressed through the central charge and conformal dimensions. A similar relation for the logarithms of the transfer-matrix eigenvalues is ascertained. These are complex-valued functions of a spectral parameter . A real part of such a function is shown to be proportional to sin , while an imaginary one - to cos. A direct geometrical interpretation of the lattice spectral parameter in the context of the conformally invariant theory for fermions inhabiting a torus is indicated. In other words, these fermions are represented as analytic anticommuting variables double (anti) periodic in a complex plane. The value of the spectral parameter coincides with an angle between these (anti) periods. A general scheme for the above expansion presumably suitable for a wide class of exactly solvable models is conjectured.     

Two-dimensional commensurate soliton structures

A phase diagram of pinned soliton structures in two dimensions has been found for a repulsive interactionU(x) between solitons withU(x)>0. The critical fugacity of the commensurate soliton structure is shown to be proportional toU(l), wherel is the period of this structure.     

Supercritical fluid chromatography and its application to analysis and preparation of high-purity compounds

The principles of supercritical fluid chromatography (SFC) and its application in various fields are reviewed. A comparison of high-performance liquid chromatography (HPLC) and SFC is performed. In discussing the applications, emphasis is placed on the possibility of using SFC in analysis of impurities in pharmaceuticals and biologically important substances and in preparation of high-purity substances. In describing detectors for SFC, special attention is paid to mass-spectrometric detectors.     

Electrodynamics of metallic photonic crystals and the problem of left-handed materials

An analytical theory of low frequency electromagnetic waves in metallic photonic crystals with a small volume fraction of a metal is presented. The evidence for such waves has been obtained recently by experiments and computations. The cutoff frequency of these waves, omega(0), is studied. An analytical expression for the permittivity epsilon is obtained and shown to be negative below omega(0). If the crystal is embedded into a medium with a negative mu, there are no propagating modes at any frequency. Thus, such a compound system is not a left-handed material (LHM). The recent experimental results on the LHM are discussed.     

Thermodynamic Modeling of Actinide Complexation with Acetate and Lactate at High Ionic Strength

The stability constants of NpO ₂ ⁺ , UO ₂ ²⁺ Am³⁺, and Th⁴⁺ with acetate and lactate anions has been measured in 0.3–5.0m NaCl media at 25°C by the solvent extraction technique. For the 1:1 complexation, the values of the stability constants increased in the order: NpO ₂ ⁺ < Am³⁺ < ₂ ²⁺ < Th⁴⁺, in accordance with the actinide charge density and reflecting the strongly ionic bonding of the complexes. The Pitzer ionic interaction parameters were calculated and used to estimate the thermodynamic stability constants at I = 0. Because our data were collected mainly in the high ionic strength region values of ⁽¹⁾ were estimated from values reported in the literature. For all stability constants the Pitzer model gives an excellent representation of the data using three interaction parameters ⁽⁰⁾, ⁽¹⁾, and COn leave from Institute of     

Small-size spectrometer for emission analysis of low-temperature plasma flows

Calculation data for characteristics of concave holographic arrays are reported, allowing development of low-size spectrometers with medium and high spectral resolution. The holographic arrays were fabricated around new subnanostructured films of chalcogenide semiconductors. A medium-resolution, small-size spectrometer was used to measure the distribution of temperature in the gas flow emanating from a DC plasmatorch with sectioned inter-electrode insert by the relative-intensity method. Presently available methods for measuring the temperature of non-uniform optically thin plasma were employed. A comparison of spectral and thermophysical methods for temperature measurements is given.     

Core level spectroscopy and RHEED analysis of KGd(WO4)2 surface

Structural and electronic characterisation of mechanically polished (010) KGd(WO₄)₂ (KGW) has been produced by reflection high-energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). With XPS analysis the original element binding energies, chemical composition and valence band structure of KGW have been determined.