Ultrahigh-density magneto-optical recording based on the effect of plasmon excitations

The analysis of ultrahigh-density recording in magneto-optical media formed with the use of granular CoAg(Au) films is performed. Due to excitation of plasma oscillations of electrons in granular CoAg(Au) films, the latter make it possible to perform additional focusing of recording radiation and to significantly decrease the size of memory cells. It is suggested that two-layer film CoAg(Au)/TbFeCo/substrate systems be used as recording media for magneto-optical recording. It is shown theoretically that the angle of the Kerr rotation of the plane of polarization θ_K upon magnetization of such a two-layer structure increases significantly in the range of incident-photon energy from 2 to 4 eV in comparison with the case of TbFeCo magnetic film. Some specific features were detected experimentally in the spectra of θ_K in the region of excitation of plasma oscillations in nanogranular CoAu and CoAg films at ? ω _P ≈ 2.5 and 3.5 eV, respectively, as well as in two-layer CoAg(Au)/TbFeCo film systems.     

Specific features of the reflection of infrared radiation by crystalline dielectrics in a magnetic field

Magnetic-field-induced variations in the reflection spectra R(λ) of the crystalline dielectrics Al₂O₃, LiF, and MgO in the infrared band (λ = 2.5–25 μm) are investigated. It is found that the reflection spectra exhibit specific features in the neighborhood of wavelengths corresponding to the excitation of optical phonon modes in the above-mentioned crystals and that a magnetic field causes an appreciable variation in the reflectivity at these wavelengths. To qualitatively describe the effect of a magnetic field on the reflection of light, the magnetoreflection spectra ΔR/R are investigated. The spectra ΔR/R exhibit sharp peaks in the neighborhood of wavelengths at which the materials under investigation are characterized by minimal reflectivity. The values of ΔR/R for p-polarized infrared radiation in a magnetic field of about 12 kOe amount to about 0.5% for Al₂O₃ at λ ≈ 9.6 μm, 7% for LiF at λ ≈ 11.1 μm, and 0.07% for MgO at λ ≈ 11.7 μm.     

Evaluating the Dynamic Load on a High-Speed Railroad Car

The internal dynamic load on a high-speed car following a real rail track with curvature and torsion is evaluated. The centrifugal, gyroscopic, tangential, and Coriolis forces and moments are taken into account. The kinematical parameters were obtained experimentally using an inertial system similar to that used to control space-rocket systems. The Euler-Lagrange equations represented by quaternionic matrices are used to determine the unknown dynamic loads in an explicit analytical form, which makes it possible to evaluate the components of dynamic loads due to the forces and moments acting on the car__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 3, pp. 119–126, March 2005.     

Using quaternion matrices to describe the kinematics and nonlinear dynamics of an asymmetric rigid body

A set of four quaternion matrices is used to represent the equations of finite rotation theory and to describe the kinematics and nonlinear dynamics of an asymmetric rigid body in space. The results obtained are tested in setting up direction-cosine matrices, calculating three-index symbols, establishing the relationship between the components of angular velocity in body-fixed and space-fixed frames of reference, and using a set of three independent rotations. Euler–Lagrange equations and a set of four quaternion matrices are used to construct a block-matrix model describing the nonlinear dynamics of a free asymmetric rigid body in three-dimensional space. The model gives the matrix Euler’s equations of motion and other special cases. Algorithms adapted to use in a numerical experiment are developed Translated from Prikladnaya Mekhanika, Vol. 45, No. 2, pp. 133–143, February 2009.     

Electronic vacuum charge for an overcritical nucleus

A “cut-off” Coulomb potential taking into account the finite size of the nucleus is finite, and a solution of the Dirac equation can be constructed for any energy, both positive and negative. In the paper we develop an exact solution of the Dirac equation for a fixed value of the total momentum j for the whole spectrum of energies, which allows us to determine the vacuum charge and its spatial distribution. We consider nuclei with different charges Z, both $Z<Z_c$ and $Z>Z_c$, where $Z=Z_c$ is the “critical” charge, at which the energy of the lowest discrete state reaches the boundary of the lower continuum $\epsilon =?m{c}^2$. Polarization of vacuum is determined, and the vacuum charge for several values of Z is found. For an undercritical nuclear charge, $Z<Z_c$, the total vacuum charge appears to be zero, while for $Z>Z_c$, the vacuum gets rearranged, and the total vacuum charge becomes equal to $?2e$. The vacuum charge distribution for $j=1/2$ for both undercritical and overcritical nuclei is calculated.     

CURRENT SPREADING ACROSS THE WIDTH OF THIN FOILS (IN SERPENTINE-TYPE SYSTEMS) OR PLANAR CURRENT SHEETS

Journal of Applied Mechanics and Technical Physics - The problem of current spreading across the width of thin foils (in serpentine-type systems) or planar current sheets is considered. The...     

Bounded Solutions of a Second-Order Difference Equation with Jumps of Operator Coefficients

Ukrainian Mathematical Journal - We study the problem of existence of unique bounded solution of a second-order linear difference equation with jumps of operator coefficients in a...     

Preparation of polymeric nanostructured materials

A procedure for forming nanostructured materials by impregnation filling of pores of poly(ethylene terephthalate) track membranes with polymeric compounds was examined. The relationships of formation of these materials were elucidated, and the structural and surface properties of these materials were studied.     

Synthesis of bilayer composite nanomembranes with conductivity asymmetry

The structure and electrochemical properties of polyethylene terephthalate track membranes modified in acetylene plasma are studied. It is found that polymer deposition on the track membrane surface using acetylene polymerization in plasma results in the case of formation of a semipermeable layer covering pores in formation of a composite nanomembrane featuring asymmetry of conductivity in solutions of electrolytes: a rectifying effect similar to that of a p-n junction in semiconductors. It is shown that the observed effect of conductivity asymmetry is caused by a significant decrease in the diameter of pores in the plasma-deposited polymer layer and a change in the pore geometry, same as existence of an interface between the initial membrane and polymer layer that have a different concentration of carboxyl groups in the surface layer. The impedance spectroscopy method allowed obtaining information on ion transfer in the studied membranes.     

Entanglement of one-magnon Schur-Weyl states

We investigate the entanglement properties of symmetry states of the Schur-Weyl duality. Our approach based on reduced two-qubit density matrices, and concurrence as the measure of entanglement. We show that all kinds of “entangled graphs", which describe the entanglement structure in Schur-Weyl states are completely coded in the corresponding Young tableau.