The conduction current in a metal-insulator-metal structure

The flow of the conduction current in a metal-insulator-metal structure under X-ray and optical excitation is considered. Accumulation of positive charge at the negative electrode in the KBr and CsI crystals is studied. The method of discharge currents after the X-ray and optical excitation is suggested for estimation of the near-surface charge. It is shown that the values of charge transported by the conduction current and those determined from the measured discharge-current signal are in satisfactory agreement. The lifetimes of near-surface charges of holes and anionic vacancies and the values of the electric-field strength at the metal-insulator interface are estimated. It is assumed that electroneutrality of the sample is established owing to the motion of electrons from the surface into the bulk over dislocations.     

Exact value of conjugate ion current in an electrolyte in the Gurevich-Kharkats diffusion-migration model

The exact solution of the problem of ion transport current in an electrolyte in the presence of a conjugate flow of solvent is obtained in the framework of the one-dimensional Gurevich-Kharkats diffusion-migration model; the conditions for the existence of the solution are analyzed.     

Giant magnetoresistance of iron-chromium superlattices at microwaves

Interaction between an rf electromagnetic field and the Fe/Cr superlattice placed in a rectangular waveguide so that a high-frequency current passes in the plane of superlattice layers is considered. The transmission coefficient versus the magnetic field strength is found at centimeter waves, and a correlation between this dependence and the field dependence of the dc magnetoresistance is established. It is shown that a change in the transmission coefficient may greatly exceed the giant magnetoresistance of the superlattice. The frequency dependence of the microwave measurements has an oscillatory character. The oscillation frequencies are analyzed in terms of wavelet transformation. Two types of oscillation periods are found to exist, one of which corresponds to the resonance of waves traveling in the superlattice along the direction parallel to the narrow wall of the waveguide.     

Perpendicular magnetic anisotropy in single-crystal Co<Subscript>50</Subscript>Pt<Subscript>50</Subscript>/MgO(100) films

The crystal structure and hysteretic magnetic properties of equiatomic single-crystal CoPt films applied on MgO substrates by magnetron sputtering, as well as modification of these properties by thermal annealing, are studied. Heat-treated films of thickness in the range 2<d≤16 nm exhibit perpendicular magnetic anisotropy. A correlation between the crystalline anisotropy constant of the CoPt films and the order parameter of the LI₀ superstructure in these alloys is found. The effect of a single-crystalline MgO substrate on the structure and magnetic properties of equiatomic CoPt films is revealed.     

Stimulated raman scattering in fiber-optic communication lines

Stimulated Raman scattering (SRS) in a long-distance fiber-optic communication line with wavelength-division multiplexing (WDM) is studied theoretically at a high power of the signal transmitted. A new criterion for determining the SRS threshold is used to calculate the critical input power versus the number of optical channels and frequency separation between them. The theoretical model is verified experimentally. SRS interaction between two channels in a communication line with an SRS amplifier for which the optical waveguide of the line serves as a nonlinear medium is measured.     

Theory of magnetoelectric effect in double-layer ferromagnetic-piezoelectric structures

A theory of magnetoelectric effect in double-layer ferromagnetic-piezoelectric plate-shape structures is presented. Using the material and motion of continuum equations, an expression for the magnetic coefficient is derived in terms of the parameters characterizing the magnetic and piezoelectric phases. It is shown that in the region of electromagnetic resonance there is a considerable increase in the magnetoelectric coefficient value. A relationship is obtained between the ferromagnetic and piezoelectric thicknesses for which the magnetoelectric coefficient is maximal. The coefficients calculated for the structures based on permendure — plumbum zirconate-titanate are given, and the results of calculations are compared to the experimental data.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–6, December 2004.     

Magnetic Properties of Iron-Based Amorphous Metal Wires

It has been studied how the conditions of machining and the elastic tensile stresses affect the magnetic properties of amorphous metal wires of composition Fe₇₅Si₁₀B₁₅ produced by drawing from a melt. The magnetic characteristics of wires subjected to both thermal treatment and treatment with a continuous electric current of different magnitude have been investigated. The residual induction of wires is their magnetic parameter most sensitive to the conditions of treatment. The dependences of the residual induction on temperature and on the magnitude of the treating electric current are qualitatively similar. The greatest changes in residual induction are observed in the range of treating electric currents from 0.5 to 0.8 A, which can be associated with the processes of structural relaxation and crystallization occurring in the wires. The run of the dependence of the residual induction on the magnitude of tensile stresses is nonmonotonic in character and is determined by the level of internal hardening stresses of the test wires.