Vol 82, No 8 (2018)

Results from physical and mathematical simulations of an inductive–capacitive converter (ICC) based on a new passive element in the theory of electrical circuits, a coil capacitor (katkon), are presented. The resonance modes are analyzed, the experimental and analytical frequency characteristics of a katkonbased physical ICC model are plotted, and the adequacy and correctness of the proposed mathematical model are confirmed.

Problems of creating physical properties and magnetic and hysteresis characteristics for active hard-magnetic materials of the rotors of highspeed and ultra-highspeed hysteretic electromechanical energy converters are considered. The effect and importance of the mechanical activation of the initial powder medium, and the phase and structural changes that occur in the powder composition of hard-magnetic materials of an Fe–Cr–Co system during mechanical activation in different media with addition of surfactants, are investigated.

Based on an analysis of the dispersion relation for a backward spin wave in a tangentially magnetized ferrite slab, expressions are obtained that describe the cutoff angles of the wave and group velocity vectors for all modes of this wave.

It is found that considering the dissipation of surface spin waves propagating in arbitrary directions in a magnetized ferromagnetic film results in a substantial change in the dispersion surface: it is transformed from an infinite surface into a closed and bounded one consisting of an upper part with strong attenuation and a lower part with weak attenuation that join along an inclined ellipsoidal curve. The change in the dispersion surface is shown to have a considerable effect on the directions of the group velocity of the waves.

Magnetic resonance properties characteristic of nanogranular film structure Ni_mC_{100 − m} with different concentrations m of its magnetic phase are studied. Samples are subjected to annealing at temperatures of 200 and 300°C. With tangential magnetization in the planes of films with m ranging from 70 to 89.8 at %, anisotropy is observed for the resonance field and the width of the absorption line. This anisotropy is explained by the uneven shapes of magnetic granules along different directions in the films.

The penetration of an electric field into a conductor with conduction electrons in a nondegenerate state is investigated. It is shown that the screening of an electric field is much more efficient in a nonlinear mode than in a linear mode.

The regime of 180° pulsed magnetization reversal of ferrite-garnet films with planar anisotropy in the region of external fields, in which the mechanism of uniform rotation of the magnetization operates, is investigated for the first time. An analysis of numerical solutions of the Landau–Lifshitz equation and our experimental studies show that, as in the case of the 90° pulsed magnetization, the presence of biaxial anisotropy in real ferrite–garnet films also leads to the so-called “effect of delayed acceleration of the transient process.” In addition, it is found that under certain conditions it is possible to achieve two stable final positions of the magnetization vector that correspond to 180° and 90°.

The theory of magnetic domain ordering in magnetic film materials with asymmetric magnetic heterogeneity is considered, with allowance for changes in the magnetostatic energy and that of the anisotropy of a curved domain boundary. The effect the parameters that determine changes in the energy of the magnetostatic interaction of the domain structure and the energy of the anisotropy of the curved domain boundary have on the shape and value of domain boundary bending is analyzed.

The conditions under which a useful signal modulating a surface spin wave is not distorted and its propagation in a ferrite film can be characterized using the group velocity concept is studied. It is shown that the greater the ratio of the first and second derivatives of the dispersion dependence for the spin wave, the greater the distance this signal can pass without distortion. It is found that for a surface spin wave, the best conditions for the transmission of the useful signal are observed for a small region of wave numbers in the initial part of the wave spectrum, where this distance can be as great as several millimeters.

The effect of magneto-pulse processing on the microstructure and magnetic behavior of amorphous electrotechnical steel is studied. It is found that the directed ordering of Fe atoms helps to increase specific magnetization of saturation and the coefficient of the squareness of the hysteresis loop, and is related to ordering of the spin system.

The formation of light bullets and the generation of a broadband supercontinuum with the minimum wavelength in the UV region are observed upon the filamentation of a femtosecond laser pulse in transparent dielectrics under conditions of an anomalous dispersion of group velocity. The duration of a light bullet, measured via laser coloration, is around one period of the light field’s oscillation, and its diameter is less than 10 μm. Numerically calculated parameters of the light bullet are in good agreement with experimentally measured values.

Periodic modulation of the decay of a stimulated photon echo (SPE), formed in a three-layer textured thin ZnO/Si (P)/Si(B) film with a longitudinal uniform magnetic field upon increasing the time interval between the exciting pulses, is recorded in experiments. The shape of the modulated SPE decay curve changes for different values of time interval between the first two exciting pulses. The g-factor of the quantum transition is estimated from the period of modulation. The value of the g-factor is used to reach a conclusion on the formation of photon echoes on localized complex exciton states of the trion type.

The characteristic durations of energy exchange for Ce³⁺ impurity centers with lattices in a LiLuF₄ crystal and the characteristic lifetime of free photoexcited charge carriers are determined in time-resolved experiments using a pump–probe scheme. The absorption saturation parameters of femtosecond laser pulses with a wavelength of 263 nm are characteristic of a slow absorber that participates in absorption from the excited state.

The quantum size effects of colloid water-organic media synthesized nanocomposites (CdSe–CdS core–shell) in toluene solution is studied. Femtosecond fluorescence up-conversion spectroscopy is used to establish that quantum dots are characterized by a biexponential decay of luminescence kinetics: the decay times are 1.8 and 26.8 ps for nanoparticles with average sizes of 2 nm and 4.5, and 68 ps for nanoparticles with an average size of 2.9 nm.

A technique for image processing and the localization (tracking) of fluorescent nanoparticles is developed on the basis of the Hough transform. Features of data analysis in the Hough parametric space that are due to the need to display the coordinates of single point emitters in 3D space are discussed. Examples are given of tracking single point emitters in the form of colloidal semiconductor CdSe/ZnS nanocrystals.

A quantum transistor based on an atomic–photon molecule is proposed. It is a linear chain of three coupled microresonators, each of which contains one resonant atom. The circuit of the proposed quantum transistor is scalable and can be used to create a quantum logical CNOT gate.

A new automated way of monitoring oncological diseases that combines forced luminescence and stimulated Brillouin scattering is proposed. Characteristics are studied of the transmission spectra of human colorectal (HT-29) and human cervical (HeLa) adenocarcinoma cells and tumor markers for PCR in water at the amounts needed for initial identification with 95% probability. The results are used to create a model of a device for monitoring oncology at its early stages.

The strain field stochastic behavior of active nanoelements with variable parameters is studied in an individual layer of a multilayer fractal quantum system. The variable parameters result in effective attenuation and the wave behavior of the shear function. The order of individual nanoelements in a coupled system affects the behavior of the strain field.