bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of micro-and nanostructures under the influence of femtosecond laser radiation on carbon samples in liquid nitrogen
Authors: Khorkov K S , Kochuev D A , Ilin V A , Chkalov R V , Prokoshev V G
Published: December 2019

The paper presents the results of an experimental study of carbon nanostructures and microcrystals formation under the influence of femtosecond laser radiation in liquid nitrogen. In addition to the formation of carbon nanopeaks on the surface, graphene exfoliation, it is possible to form carbon microcrystals due to the mechanism of the subsurface overheating.
Surface features of the AlN optical coating deposited on the facet of a high-power AlGaAs/GaAs semiconductor laser
Authors: Fomin E , Bondarev A , Slipchenko S , Rudova N , Pikhtin N
Published: December 2019

The facets of high-power AlGaAs/GaAs semiconductor lasers were coated with thin dielectric AlN films using reactive ion-plasma technique. The refractive indices of the films were measured by the ellipsometry. It is shown the technique makes it possible to obtain AlN films with a refractive index close to that of a single-crystal material. The scanning probe microscopy was used to estimate the surface roughness of the films. The comparative results of the aging tests of lasers based on the same laser heterostructure with SiO2 and AlN coatings on their facets are presented.
Changing of mechanical characteristics of Co-based amorphous alloy and Fe-based nano-crystalline alloy in the hydrogenous medium under the influence of impulse electric current
Authors: Pluzhnikova T N , Fedorov V A , Yakovlev A V , Pluzhnikov S N , Fedotov D Y
Published: December 2019

Experimentally established the preliminary influence of hydrogen-containing medium (NACE) in cobalt-based amorphous alloys reduces the temperature of the onset of ductility during annealing. The structure of the surface changes forming in the holding of samples in the NACE medium either separate NaCl crystals or branched crystalline structures on the surface. A layer of oxide appears on the nanocrystalline alloy is preventing in heat exchange between the sample and environment. The passing of the impulse electric current j = 108 – 109 A/m2 results increases mechanical stress releases comparing to non-affected samples by the hydrogen-containing medium because of the temperature increase. The amorphous structure proves to be more resistant under simultaneous influence with the impulse electric current to the effect of the hydrogen medium NACE compare to the nanocrystalline one.
Thin amorphous silicon films crystallization upon flexible substrates
Authors: Serdobintsev A A , Luzanov V A , Kozhevnikov I O , Ryabukho P V , Mitin D M , Bratashov D N , Starodubov A V , Pavlov A M
Published: December 2019

A novel method for thin silicon films crystallization that combines advantages of laser- and metal-induced crystallization technologies is reported. Polycrystalline silicon films were synthesized on flexible polyimide substrates following the proposed approach. Films obtained possess high crystal structure regularity and crystallinity.
Growth and optical properties of GaPN/GaP heterostructure nanowire array
Authors: Koval O Yu , Sapunov G A , Fedorov V V , Mukhin I S
Published: December 2019

The study is devoted to synthesis and investigation of the optical properties of GaPN/GaP nanowire (NW) arrays grown on Si substrate (111) with plasma-assisted molecular beam epitaxy (PA-MBE). First, we demonstrate the growth of axial GaPN/GaP and GaP NW heterostructures. The morphology of GaP and GaPN/GaP NW arrays was investigated with scanning electron microscopy (SEM) to show that at low growth fluxes of activated nitrogen self-catalytic growth regime and nanowires morphology are preserved. Raman spectroscopy was used for investigation of phonon spectra features. Optical properties of the GaPN NW arrays were determined at room temperature with photoluminescence (PL) spectroscopy. Analysis of both Raman spectroscopy and PL results allowed to analyze the GaPN/GaP NWs chemical composition. Dilution of GaP NWs with N allows to significantly increase PL intensity and obtain broad PL signal in the optical spectral region demonstrating the potential of GaPN NWs for future nano-optoelectronics and photonics.
Raman spectroscopy estimation of the carrier concentration and the value of strain in monolayer graphene films grown on 4H-SiC
Authors: Eliseyev I A , Davydov V Yu , Smirnov A N , Nestoklon M O , Dementev P A , Lebedev S P , Lebedev A A , Bokai K A , Usachov D Yu
Published: December 2019

Comprehensive study of high-quality monolayer graphene samples grown by thermal destruction of the Si-face of the 4H-SiC substrate was carried out. Analysis of the data obtained by Raman spectroscopy and angle-resolved photoemission spectroscopy suggest the need to use the Fermi velocity in the graphene layer under study to obtain a correct estimate of the electron concentration and strain values using Raman data. This statement is valid not only for graphene on the SiC substrate, but for graphene on any other substrate as well, since the Fermi velocity in graphene depends on the dielectric constant of the substrate.
Dielectric spectroscopy of thermoplastic polyimide R-SOD in the region of medium and high temperatures
Authors: Dao T H , Nikonorova N A , Castro R A
Published: December 2019

Molecular mobility and charge transport in R-SOD aromatic thermoplastic polyimide were studied by dielectric method. Dielectric spectra of all samples in the examined temperature and frequency range revealed two regions of dipole polarization relaxation. The β- process is determined by local motion of the phenyl rings in the diamine and dianhydride moieties of the macromolecule with the adjacent groups. The α-process can be associated with crossing the glass transition temperature, i.e., with the segmental large-scale mobility of the main chains. The introduction of nano-additives (R-SOD 3%) does not change the relaxation times in the regions of β and α process, but leads to an increase in intensity compared to pure polyimide R-SOD.
Crystal structure transformations during phase transitions in homologues of n-alkanes: C23H48, C24H50, C25H52 as revealed by FT-IR spectroscopy
Authors: Gur’eva S A , Marikhin V A , Myasnikova L P , Volchek B Z , Medvedeva D A
Published: December 2019

The dependence of the IR absorption spectrum on the type of symmetry of crystallographic cells allowed us to investigate the kinetics of phase transitions. It is confirmed that the first order solid-phase transition develops by a heterogeneous mechanism in a narrow temperature range ΔT ⩾ 1 K.
Study of GaAs oxidation in the low-current Townsend discharge
Authors: Lodygin A N , Portsel L M , Snigirev L A , Kirilenko D A , Astrov Yu A
Published: December 2019

An anodic oxidation of GaAs substrates in a non-self-sustained low-current dc Townsend discharge is investigated. The process is carried out at the room temperature in a three-electrode microreactor filled by 98%Ar + 2%O2 gas mixture. Investigation of the oxidation kinetics indicates that the formed oxide is characterized by a high resistivity, ρ ∼ 1011 Ω·cm. It is demonstrated the application of the method for formation of oxide films with dimensions of tens of microns, which thickness is on the nanometer scale. Examination of the “GaAs substrate - oxide layer” interface using the high resolution transmission electron microscopy has revealed that the oxide is characterized by the amorphous structure.
Optical properties of CdTe/ZnTe structures with thin CdTe layers
Authors: Agekyan V , Chukeev M , Filosofov N , Karczewski G , Resnitsky A , Serov A
Published: December 2019

The optical properties of series of CdTe/ZnTe heterostructures with two built-in planar CdTe inclusions of thickness 4.0 and 1.5 monolayers are investigated. The temperature behavior of the exciton luminescence intensity at above-barrier and under-barrier excitation depends on the ZnTe barrier thickness which varies from 15 to 55 monolayers. It occurs that the shape of exciton luminescence bands changes strongly under the increasing optical excitation. The excitation luminescence spectra are studied in the temperature range 5 – 80 K.
Nanoscale films of bismuth and antimony: production technologies and properties
Authors: Makarova E S , Tukmakova A S , Novotelnova A V , Kablukova N S
Published: December 2019

We studied the line of bismuth and antimony thin films obtained by thermal evaporation with or without additional annealing or zone recrystallization under a coating. The dependence of film structure on the production technology and substrate type has been shown. The dependence of galvanomagnetic properties of thin films on the structure has been investigated.
Two-dimensional position-sensitive spectrometer for registration of ionizing radiation
Authors: Bogdanov A A , Eremin I V , Chichagov Yu V , Eremin V K , Tuboltsev Yu V , Verbitskaya E M , Bezbah A A , Fomichev A S , Kiselev O A , Kostyleva D A
Published: December 2019

A new two-coordinate position-sensitive spectrometer for the measurements of spatial and energy distribution of ionizing particles was developed. The sensitive elements of the device are two orthogonal 64 strip semiconductor detectors whose signals are read out by two Application-Specific Integrated Circuits (ASIC) IDE1140 comprising 64 spectrometric channels each. Control, pre-processing data acquisition and transfer to a computer are carried out using FPGA circuit EP3C16Q240. The main spectrometer characteristics obtained in the measurements are: equivalent noise charge of 0.7 fC and integral nonlinearity is below 1% in the range from 5 to 160 fC.
Measurement of short-lived Φ(1020) and K*(892)0 resonances in heavy-ion collisions at NICA energies using the MPD experiment
Authors: Ivanishchev D. , Kotov D. , Malaev M. , Riabov V. , Ryabov Yu.
Published: December 2019

The K*(892)0 and Φ(1020) mesons are copiously produced in hadronic and heavy-ion collisions and carry a wealth of information on different aspects of the interactions, including the properties of the hadronic phase, relative interplay of the radial flow and coalescence at intermediate momentum. For these reasons, measurements of K*(892)0 and Φ(1020) production is an important part of the experimental program of the MPD experiment at NICA. We discuss prospects for K*(892)0 and Φ(1020) measurements in the MPD experimental setup as well as results of the feasibility studies performed using the full-scale Monte Carlo simulations of the detector response.
Studying the mechanisms of the hadron jets production in U+U collisions at

NsN=192

GeV
Authors: Berdnikov A. , Berdnikov Ya. , Kotov D. , Zharko S. , Radzevich P.
Published: December 2019

Studying the properties and evolution of the quark-gluon plasma (QGP) is one of the main directions in modern nuclear physics. The leading direction in the QGP studies is the research of the particle production originating from hard scattering of partons produced in the ultra-relativistic heavy nuclei collision. Light mesons (π0, η and KS
) invariant spectra and nuclear modification factors measurements at high transverse momenta are used for the parton energy loss models free parameters estimate in large systems and to examine various scaling behaviours. Spherically asymmetric uranium nuclei at

N

s

N

=
192

GeV are used to determine the influence of geometrical parameters of the colliding system on the fragmentation of hard partons produced in high energy collision of heavy nuclei. This paper presents differential transverse momentum spectra and nuclear modification factors of KS
mesons in U+U collisions at

N

s

N

=
192

GeV measured in a wide transverse momentum range and different centrality intervals with PHENIX experiment at RHIC.
Jet-Quenching Studies Using Leading Mesons in Cu+Au Collisions at

NsN=200

GeV
Authors: Berdnikov A. , Berdnikov Ya. , Kotov D. , Radzevich P. , Zharko S.
Published: December 2019

Quark-gluon plasma (QGP) is a hot and dense color-charged medium, created in ultra-relativistic heavy nuclei collisions. Jet-quenching is one of the evidence for QGP formation and manifests itself in suppressed hadron production at high transverse momenta when compared to proton-proton collisions. We present results of jet-quenching studies in Cu+Au collisions at

N

s

N

=
200

GeV using production of leading mesons (π
0, η, KS
, ω). Measurements are performed with PHENIX spectrometer at RHIC. Yields of π
0, η, KS
, and ω mesons and reconstructed jets show the same suppression level at high transverse momenta region within uncertainties when compared to p+p results. The suppression level of π
0, η, KS
, and ω mesons in Cu+Au collisions is equal within uncertainties to one measured in Au+Au and Cu+Cu collisions at

N

s

N

=
200

GeV at similar participant nucleon numbers.
Study of neutral meson production with photon conversions in the MPD experiment at NICA
Authors: Kryshen E , Ivanishchev D , Kotov D , Malaev M , Riabov V , Ryabov Yu
Published: December 2019

The MPD experiment is aimed to study strongly interacting matter in nucleus-nucleus collisions at the future NICA collider in the energy range 4-11 GeV per nucleon pair. Neutral pion and η measurements via two-photon decays will allow the MPD experiment to extend the variety of registered particle species and will provide important information on dynamics and properties of the medium created in heavy ion collisions at NICA energies. The measurement of neutral pion and η meson spectra is also important as a first step towards the analysis of thermal photons sensitive to the temperature of the produced medium. In this contribution, the feasibility of neutral meson production measurements in the two-photon channel via photon conversions will be presented, and implications for the study of thermal photons will be discussed.
Resonant Bragg reflection of light from ZnTe-based structures with embedded CdTe monolayers
Authors: Ukleev T A , Reznitsky A N , Sel’kin A V
Published: December 2019

An electrodynamic model describing Bragg reflection of light from semiconductor structures with ultrathin planar layers embedded in bulk material matrix is developed. The layers are assumed to exhibit resonant optical properties in a spectral range near the short-wavelength bandgap edge of bulk material. Model calculations of the reflection spectra are performed at typical parameter values of the resonant Bragg structure containing monolayers of CdTe in bulk ZnTe.
Investigation of the optical properties of a spherical distributed Bragg reflector
Authors: Dukin A A
Published: December 2019

The dependence of the optical properties of a spherical distributed Bragg reflector (SDBR) on the radius of the SDBR core is studied. The SDBR reflection spectra were calculated by the method of spherical wave transfer matrices for different polarizations and different angular modal numbers of spherical waves. It is shown that if the core radius is much larger than the Bragg wavelength in the core substance, the width and spectral position of the stop-band are the same for both polarizations (TM and TE) of spherical waves and do not depend on the angular modal number of the spherical wave. If the core radius is less than several Bragg wavelengths in the core substance, a narrow dip appears in the reflection spectrum in the region of the stop-band for one polarization and some values of the angular modal number of spherical waves. It is shown that the reason for the appearance of this dip is the occurrence of a resonance in the SDBR quarter-wave layer closest to the core.
Destruction of the orbital angular momentum in combined singular beams
Authors: Akimova Ya E , Bretsko M V
Published: December 2019

This paper shows the dependence of the orbital angular momentum (OAM) of combined singular beams on the magnitude of the local perturbation in the holographic grating. In the absence of a perturbation of the holographic grating, the OAM acquires a maximum value numerically equal to the topological charge of the singular beam. With weak disturbances of a regular holographic grating, dips in the orbital moment appear. The depth of the dips increases rapidly with increasing disturbance. It is shown that even a weak perturbation of the lattice leads to a sharp increase in the contribution of partial beams with other topological charges. The reliability of the results obtained confirms the high degree of correlation of the intensity distribution of the original and reconstructed combined beams.
Measurement of vortex spectrum in a purely degenerate vortices array
Authors: Bretsko M V , Akimova Ya E
Published: December 2019

The article presents a new method for determining the basic characteristics (square of amplitude and initial phase) of purely degenerate arrays of optical vortices using intensity moments. Under purely degenerate arrays, a complex beam is assumed, in which the magnitude of the square of the amplitude of the vortices, opposite in sign of the charge, is equal, and the phases take only two values 0 and π. When the frequency parameter changes in hundredths of decimal places, the internal structure of the complex beam can be significantly changed, which is well reflected by the results obtained.
Influence of the geometric and physical parameters of the dielectric optical micro-waveguides with rectangular cross section on their losses
Authors: Zaretskaya G A , Drozdovskii A V , Cheplagin N A , Kalinikos B A
Published: December 2019

Formation of losses in the dielectric optical micro-waveguides of rectangular cross section is analytically studied. It is shown that the two processes are involved in the formation of the frequency characteristic of the attenuation constant: the redistribution of energy in the waveguide-environment system and the group velocity dispersion. The group velocity dispersion determined by the geometry of the waveguiding structure leads to the formation of a local maximum of the attenuation constant in the frequency response.
In situ optical monitoring of CVD growth and reactive ion etching of nanodiamonds with silicon - vacancy colour centres
Authors: Grudinkin S A , Feoktistov N A , Golubev V G
Published: December 2019

A method of in situ optical monitoring of the CVD growth and reactive ion etching of nanodiamonds with silicon-vacancy colour centres is presented. The method is based on measuring the time dependence of the optical reflectivity from a silicon substrate with deposited isolated nanodiamonds. Evolution of the reflectivity due to the light scattering on nanodiamonds is a result of the changes in their size and structure during growth and etching. Optical monitoring of the growth and etching processes allowed reproducible fabrication of high crystalline quality nanodiamonds.
Research of component composition of bioimplants for treatment of gum recession using a Raman spectroscopy method
Authors: Timchenko P E , Timchenko E V , Volova L T , Frolov O O , Yagofarova E F
Published: December 2019

Research of component composition of bioimplants for gum recession treatment using the Raman spectroscopy method is presented in this paper. Spectral assessment of the component composition of hard palate bioimplants prepared by the «Lioplast» technology before and after lyophilisation is carried out. Expanded component analysis of the researched objects using the deconvolution method shows that the difference in relative component composition of the two groups of samples is seen at wavenumbers of 1446, 1738, 1660 cm−1 (lipids & fatty acid), 852 and 938 cm−1 (proline), 1062 cm−1 (GAGs), 1204 cm−1 (tyrosine), 1555 cm−1 (amide II). The criteria that allow assessing the composition and quality of the prepared bioimplants are given on the base of spectral analysis. It is shown in the paper that the developed optical method of biomaterial assessment can be used for the process optimization and to select individual processing parameters.
Digital holographic disdrometer for precipitation monitoring
Authors: Ekimov Dmitry
Published: December 2019

The paper proposes and discusses the optical design and design features of a digital holographic disdrometer that combines the advantages of optical and 2D video disdrometers. The developed device has a measuring area size more than 100 cm2, the size range of the analyzed particles is up to 20 mm, the resolution is 15 μm and allows you to receive and analyze images of hydrometeors.
The use of Raman spectroscopy and methods of quantum chemistry for assessing the relative concentration of triglycerides of oleic and linoleic acids in a mixture of olive oil and sunflower seed oil
Authors: Berezin K V , Dvoretsky K N , Chernavina M L , Novoselova A V , Nechaev V V , Antonova E M , Shagautdinova I T , Likhter A M
Published: December 2019

The Raman spectra of five samples of sunflower seed oil and five samples of cold-pressed olive oil of various brands are recorded in the range of 500–2000 cm–1. Within the framework of the B3LYP/6-31G(d)/6-31G(d,p)/6-31+G(d,p)/6-311G(d)/6-311G(d,p)/6-311+G(d,p) methods, the structural models of eight fatty acids (oleic, linoleic, palmitic, stearic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic) are constructed, and also within the framework of the B3LYP/6-31G(d) method, the structural models of triglycerides of the first four of the above acids are obtained. The vibrational wavenumbers and intensities in the IR and Raman spectra are calculated. The Raman spectra of olive oil and sunflower seed oil were simulated by using the supermolecular approach. We investigated the dependence of the relative intensity of the vibrational bands νexp=1660 and 1445 cm–1 on the concentration of triglycerides in oils of oleic and linoleic acids and the dependence of the intensity of these bands on the degree of saturation of fatty acids.
Development of a new method for determining the parameters of a moving object based on the study of the structure of the magnetic track of colloidal solution nanoparticles
Authors: Logunov S E , Davydov V V , Rud’ V Yu
Published: December 2019

A new method has been developed for the study of deep-sea areas of the marine area (more than 550 m depth) based on the measurement of the parameters of a magnetic track from a moving magnetic object. A method for detecting a magnetic track from a moving magnetic object using an optical sensor is proposed. Studies of changes in the parameters of the magnetic field in the magnetic track using ferromagnetic fluid have been conducted.
Electron g-factor in coupled quantum wells CdTe and CdMnTe
Authors: Afanasiev M M , Kozyrev N V , Kirstein E , Kalevich V K , Zhukov E A , Mantsevich V N , Krivenko I S , Karczewski G , Yakovlev D R , Kusraev Yu G , Bayer M
Published: December 2019

In tunnel-coupled quantum wells (QWs) CdTe (20 nm wide) and CdMnTe (8 nm wide) separated by Cd0.88Mg0.12Te barrier with a thickness of L
B = 5, 7, 9, and 11 monolayers (MLs), the dependence of electron g-factor on the barrier thickness and temperature is investi-gated by means of the pump-probe Kerr rotation technique. The renormalization of the electron g-factor occurs due to the s–d exchange interaction of electrons with manganese ions in a magnetic QW. The most change of the electron g-factor value Δg = 0.25 is registered at the least barrier width of 5 MLs and temperature T = 5 K. In this case, the penetration of the electron wave function from the nonmagnetic QW into the magnetic one is estimated to be 0.6%.
The study of the spectral characteristics of biological tissues for optimization of surgical lamp parameters
Authors: Mamoshin A V , Seryogina E S , Potapova E V , Shepeleva A I , Shupletsov V V , Dunaev A V , Aladov A V , Chernyakov A E
Published: December 2019

During surgery, it is important for the surgeon to determine the optimal lighting conditions for contrast imaging of the operated objects. The paper analyzes various parameters of a controlled colour-dynamic surgical lamp based on a powerful led when contrasting individual organs and tissues of model animals, as well as optical parameters of the organs themselves. The results will allow developing a library of colours and lighting settings for a wide range of surgical operations.
Measuring the orbital angular momentum of light beams by using a single intensity distribution
Authors: Kovalev A A , Kotlyar V V , Porfirev A P , Kalinkina D S
Published: December 2019

Here, we modify and study a method for measuring the orbital angular momentum (OAM) based on angle-averaged intensity in a single transverse plane. We also simulate propagation of a superposition of two Laguerre-Gaussian modes after passing through a diffuser with a random phase. Despite the distortions caused by the diffuser, the modified method allows OAM measurement with an average error less than 10%. The main advantages of the described technique is that (i) simultaneously with the full OAM the OAM spectrum is obtained and (ii) no any optical elements are needed.
Infrared photoluminescence spectra measurements using boxcar integrator in the active baseline subtraction mode
Authors: Luferau A I , Firsov D D , Komkov O S
Published: December 2019

A photoluminescence (PL) measurement method using boxcar integration in the active baseline subtraction mode has been implemented. It allows for infrared PL measurements with a low duty cycle of the pump pulse, thereby minimizing the uncontrolled heating of the structure under study. The implemented method was compared to phase-sensitive detection by signal-to-noise ratio of the resulting spectra, indicating its superior performance at low duty cycles. The decrease in uncontrolled heating of the structure under study was confirmed by observing a change in the ratio of temperature-sensitive PL peaks of a test InSb/InAs/InGaAs/InAlAs/GaAs nanoheterostructure.
Metastable states of the fractal-cluster structure of alcohol-containing aqueous solutions
Authors: Shostka V I , Shostka N V
Published: December 2019

The paper presents the results of the study of fractal-cluster structures formed in the near-surface layer of alcohol-containing aqueous solutions. Water-ethanol mixture when changing the concentration of alcohol in water enters a new phase with a more dense packing of fluctuating structures. Molecules of alcohol, having a larger size than water molecules, when embedded in the structure of water, significantly violate it, as a result of which the structure of the system and its properties change. To visualize these structures in the surface layer of alcohol-containing aqueous solutions, the laser interferometry method was used in the work . It was found that in the range of average concentrations of alcohol in an aqueous solution, in spite of some stabilization of the structure of the system, the solutions in it have a substantial heterogeneity in the form of changing fractal-cluster structures. On the basis of the conducted studies, possible mechanisms for the transition of fractal-cluster water structures in the interaction with ethanol into spatial clathrates are shown.
High-power 0.98 µm range diode lasers based on InGaAs/GaAs quantum well-dot active region
Authors: Kornyshov G O , Payusov A S , Gordeev N Yu , Serin A A , Shernyakov Yu M , Mintairov S A , Kalyuzhnyy N A , Nadtochiy A M , Maximov M V , Zhukov A E
Published: December 2019

We present a study of characteristics of the edge-emitting lasers operating in the 0.98 μm wavelength range and based on a new type of InGaAs/GaAs active region – quantum well-dots (QWD). Utilizing the QWD active region in broadened 1.3 μm waveguide (BWG) allowed us to decrease the internal loss down to 0.5 cm−1 and to demonstrate the maximum output power of 13W and 50W in continuous wave (CW) and pulse operation regimes respectively. The investigation of the lasing spectra under high pulse injection currents revealed the overheating of the active region in the devices with moderate waveguide thickness (0.68 μm) in contrast with BWG devices.
Accounting the quantum-confined Stark effect on the determination of the active LED region temperature
Authors: Romanovich M M , Lamkin I A , Tarasov S A
Published: December 2019

The article investigates the effect of heating of the LEDs active region (AR) on the luminescence efficiency of LEDs of various spectral ranges. As a result of the work the method for contactless determination of the active LED region temperature with account the influence of the Stark effect was created. The method is based on the analysis of the long-wave part of the spectrum whose behavior primarily depends on the crystal temperature.
Effect of random macroscopic defects on kinetic phenomena in a layered semiconductor n-InSe with strong electric fields
Authors: Abdinov A Sh , Babayeva R F
Published: December 2019

In single-crystal n-InSe layered semiconductors at 77÷300 K, the dependence of the electrical conductivity on the strength of a strong electric field by an ultrahigh frequency (UHF) was studied. It was established that at low temperatures, the magnitude and course of the change in conductivity under the action of a strong electric field in samples with different initial (existing at 77 K) specific conductivities differ. The dependence of the electrical conductivity on the electric field strength in the most low-resistance samples is satisfactorily described by the theory of heating of charge carriers by the electric field in spatially homogeneous crystalline semiconductors, and with a decrease in the value of specific conductivity, it disagrees with this theory. It is shown that these discrepancies are due to the presence of random macroscopic defects in the crystals under study, which are formed due to the weakness of the interlayer coupling.
High-power λ = 8 µm quantum-cascade lasers at room temperature
Authors: Dudelev V V , Mikhailov D A , Babichev A V , Andreev A D , Kognovitskaya E A , Bobretsova Y K , Slipchenko S O , Pikhtin N A , Gladyshev A G , Denisov D V , Novikov I I , Karachinsky L Ya , Kuchinskii V I , Egorov A Yu , Sokolovskii G S
Published: December 2019

The paper presents the results of characterization of the high-power quantum cascade lasers for 8 μm spectral range. Lasers demonstrate stable generation at room temperature with the maximum output peak power of ∼ 0.9 W per facet.
Photonic crystal waveguide for difference frequency generation in terahertz range
Authors: Savchenko G M , Sokolovskii G S
Published: December 2019

We consider a waveguided semiconductor structure with photonic crystal core for efficient difference frequency generation. The calculation of the dispersion of the eigenmodes shows that this structure pumped by radiation with wavelengths of 1000 and 1003 nm, allows the difference frequency generation at 1 THz with a coherence length of 1 cm.
Polymer Optoelectronic Bus for High-Speed Data Transmission Systems
Authors: Manvelova T A , Tarasov S A , Ivanov N N
Published: December 2019

In this paper, high-speed planar waveguides of optoelectronic data bus are suggested replacing low-throughput backplane electrical interconnects. Optical polymer polydimethylsiloxane (PDMS) and cost-efficient soft lithography technology are proposed for optoelectronic bus fabrication. In accordance with polymer optoelectronic data bus fabrication process work-out results the chosen materials and technology applicability was confirmed. As an optoelectronic bus characteristics measurement results, 14 dB/cm propagation losses value was obtained by general use materials.
The technology of increasing the energy density of batteries by controlling the degree of polarization of ferroelectrics
Authors: Zubtsov V I , Zubtsova E V , Derugin V V
Published: December 2019

The paper deals with a power plant developed with the use of ferro-piezoelectric ceramics to increase the energy density of electric vehicle batteries. Electrochemical generator in the plant makes it possible to significantly increase electrical energy by means of controlling the degree of polarization of ferro-piezoelectric ceramics. Application of the plant in an electric vehicle increases the range on a single charge by 3.5…5 times. Efficiency factor of the power plant is about 50…55% and depends on ceramics modification and electric circuit.
Dielectric Investigations and Birefringence of PbNi1/3Nb2/3O3 Single Crystals
Authors: Polushina A D , Obozova E D , Smirnova T A , Zalesskii V G , Lushnikov S G
Published: December 2019

The results of studies of dielectric response and birefringence in the PbNi1/3Nb2/3O3 (PNN) single crystal are presented. An anomaly in the temperature dependence of the complex dielectric permittivity in the vicinity 153 K has been observed. It is shown that the anomaly is attributed to the transition relaxor ferroelectric state. The presence of slightly noticeable anomaly in permittivity in the temperature range of 200-210 K has been confirmed by means of optical birefringence microscopy.
Current-driven magnetization switching and dynamic spin reorientation transition in magnetic tunnel junctions
Authors: Nikitchenko A I , Pertsev N A
Published: December 2019

We present theoretical results on electrically induced magnetization dynamics in CoFeB/MgO/CoFeB tunnel junctions connected to a constant-current source. Our calculations take into account both the spin-transfer torque (STT) created by a spin-polarized current and a voltage-controlled magnetic anisotropy (VCMA) associated with the CoFeB|MgO interface. It is shown that the current-driven spin dynamics in an ultrathin free layer of such junction is not limited by the magnetization precession and switching, but also can have the form of a dynamic spin reorientation transition, which is caused by the combined action of STT and VCMA and gives rise to a steady precessional state. Critical current densities necessary for the appearance of different types of magnetic dynamics are calculated as functions of the free-layer thickness and in-plane aspect ratio. The spin current pumped into a normal-metal overlayer by the tunnel junction with the precessing magnetization is also evaluated.
Methods for assessing pyroelectric current in ferroelectrics with first order phase transition by dielectric measurements
Authors: Mylnikov I L , Semenov A A , Dedyk A I , Pakhomov O V , Belyavskiy P Yu , Burovikhin A P , Pavlova Yu V , Ustinov A B
Published: December 2019

The creation of devices based on the electrocaloric effect requires the methods for assessing pyroelectric currents at the different external parameters. Two indirect methods for calculating pyroelectric currents in ferroelectrics are considered. The first one based on the temperature-field dependences of the dielectric hysteresis loops. The second one based on the temperature-field dependences of the dielectric constant. The original method for directly estimating the magnitude of the pyroelectric currents by the charge change with thermal flux of laser radiation pulses is proposed.
Features of spin dynamics of magnetic ions and charge carriers in self-organized quantum dots CdSe/ZnMnSe
Authors: Kozyrev N V , Kirstein E , Namozov B R , Kusrayev Yu G , Zhukov E A , Sedova I V , Yakovlev D R , Bayer M
Published: December 2019

Self-organized disk-shaped quantum dots of CdSe embedded in diluted magnetic ZnMnSe barrier were studied by means of pump-probe time-resolved Kerr rotation (TRKR) technique at low temperature T = 7 K. In absence of the external magnetic field TRKR signal exhibits long-living spin dynamics with the decay time exceeding the period between laser pulses. Such spin dynamics is not typical for diluted magnetic semiconductors and nano-structures based on them and could be a trace of a bound magnetic polaron. Resonant spin amplification measured in transversal magnetic field up to 1 T shows the only one peak near B = 0. In B = 1 T the long-living non-precessing signal practically vanishes, while the precessing one appears with the Larmor frequency corresponding to the Mn2+ ions’ net spin precession around the magnetic field. It was found that the signal consists of three components with slightly different precession frequencies that could be due to the fine structure of the manganese spin sublevels occurring because of a stress in quantum dots.
The effect of Rashba spin-orbit interaction on persistent current in a chain of two Holstein-Hubbard rings
Authors: Smolkina M O , Popov I Yu , Chatterjee A
Published: December 2019

We study the persistent current in a chain of two coupled quantum rings threaded by an Aharonov-Bohm flux in the presence of electron-phonon and Rashba spin-orbit interactions. In the framework of the Holstein-Hubbard model, the equations for ground state energy, persistent current and Drude weight were derived. Obtaining of the expression for the ground state energy allowed us to obtain the persistent current by a conventional way (differentiating). The influence of the magnetic flux and the Rashba spin-orbit interaction on the ground state energy, persistent current and Drude weight was studied numerically.
Filling of In(Ga)P/GaInP quantum dot electron states detected by microphotoluminescence
Authors: Romanova A Yu , Belyaev K G , Buriak P A , Vlasov A S , Kalyuzhnyy N A , Mintairov S A , Salii R , Lebedev D V , Rakhlin M V , Smirnov V I , Toropov A A , Bogdanov A A , Ramezanpour S. , Mintairov A M
Published: December 2019

Microphotoluminescence (μPL) spectra of single In(Ga)P/GaInP quantum dots (QD) were investigated. Measurements were carried out at different optical pump power and at different electric field with constant optical pump. Filling of electron s-, p-, d-states was observed. Quantum confinement Stark effect (QCSE) was detected. Obtained PL life times of s-, p- electron states were 0.5 ns and 0.4 ns respectively. From spectra it is clearly seen that QDs have weak quantum confinement (hω0
∼4-8meV).
Effects of collisions on the stability properties of plasma diodes
Authors: Pramanik S , Kuznetsov V I , Chakrabarti N
Published: December 2019

Stability features of the Pierce diode steady states are investigated in the presence of electron-background-particle collisions. The regime without electron reflection from the potential barriers is studied. Steady states are obtained analytically by means of the Lagrangian fluid description. Employing the first order perturbation theory, the relevant dispersion equation is derived. Both aperiodic and oscillatory solutions of this equation are found and their properties are studied.
Radiation from the shock wave front caused by its movement in plasma
Authors: Baryshnikov A S , Saharov V A , Baryshnikov I A
Published: December 2019

In the work the possibility of electromagnetic radiation of shock wave in collisional plasma is theoretically explored, radiation which stimulated specifically by movement of the shock wave. Radiation occurs across the shock wave movement and for experiments in cold plasmas – at frequency of high-frequency radiation.
Numerical study of the vortex structure influence on heat transfer in the supersonic flow past a plate and a blunt fin junction
Authors: Kolesnik E V , Smirnovsky A A
Published: December 2019

Viscous-inviscid interaction and heat transfer in supersonic 3D laminar flow past a fin-body junction is investigated by means of numerical simulation. A laminar flow regimes at the freestream Mach number equal to 4, 5 and 6 are considered. Specifics of vortex structures and shock wave pattern in the interaction region are discussed. The Mach number effect on the predicted size of separation zone upstream of the fin and the plate Stanton number distribution are analysed. For the Mach number of 5, the temperature factor influence on heat transfer is investigated.
Supersonic plasma flow injection across the magnetic arch in a table-top laboratory setup
Authors: Viktorov M E , Golubev S V , Vodopyanov A V
Published: December 2019

The dynamics of the plasma deceleration process during the injection in the tridimensional magnetic arch formed by magnetic coils is studied. The effect of the magnetic field lines deformation in the apex is experimentally observed when the plasma flow stops in the region where its ram pressure equals the magnetic pressure. The propagation direction of the plasma flow is changed as a result of plasma flow interaction with the magnetic arch. The plasma flow velocity along magnetic field lines is experimentally measured and is in a good agreement with numerical estimates of Alfven velocity. The transition layer is formed with a transverse size of the order of ionic inertial length as a result of the interaction of the plasma flow with the magnetic field. Non-thermal microwave emission of plasma is experimentally detected in the electron cyclotron frequency range during plasma deceleration process. The electromagnetic spectrum at frequencies of 1–2 GHz has been studied in detail.
Kinetic ionization and recombination coefficients in the dense semiclassical plasmas on the basis of the effective interaction potential
Authors: Shalenov E O , Seisembayeva M M , Dzhumagulova K N , Ramazanov T S
Published: December 2019

In this paper, the ionization and recombination coefficients of dense semiclassical hydrogen plasma on the basis of the effective interaction potential have been investigated. For this goal the Bohr – Lindhard method and method phase function have been applied to obtain the electron capture and ionization cross sections. The electron capture cross section has been calculated in the framework of the perturbation theory. The effective interaction potential, which takes into account the screening effects at large distances and quantum diffraction effects at short distances, was used. The results of the investigation show the behaviour of the calculated kinetic coefficients with a change in the plasma parameters: the ionization coefficient decreases with increasing density and (or) coupling parameter while the recombination coefficient increases.
Numerical study of dissolved gas release induced by cavitation in a high speed channel flow
Authors: Iben U , Makhnov A , Schmidt A
Published: December 2019

Cavitation often leads to performance degradation of hydraulic devices and, in some cases, to damage of the elements of their constructions (cavitation erosion). Liquids, that are used in technical devices, often contain dissolved gas. Such liquids are of particular interest because cavitation causes release of the dissolved gas into the cavities which can significantly change the flow structure. Mathematical models based on detailed description of all the underlying mechanisms still need development. The approach that was proposed and analyzed in the present study combines a simplified equilibrium model of liquid-vapor phase transition with a non-equilibrium diffusion model describing gas release process. The distributions of the hydrodynamic parameters and the gaseous phase fraction obtained show significant influence of the dissolved gas on evolution of cavitation structures. This is in qualitative agreement with experimental observations regarding the main features of cavitating flows and the behavior of the degassed air. It demonstrates robustness of the proposed simulation algorithm which means that its further development can be a promising way to create a universal model for reliable quantitative prediction of dissolved gas release.
Charged particles distribution ahead the shock wave front in the electrode discharge plasma
Authors: Baryshnikov A S , Basargin I V , Bezverkhnii N O , Bobashev S V , Monakhov N A , Popov P A , Sakharov V A , Chistyakova M V
Published: December 2019

Experiments on the interaction of a shock wave with a glow discharge were conducted. It was established that the shock wave propagation is accompanied by a change in the potential of the discharge plasma. The varying potential in the glow discharge plasma causes a distortion of the double probe current. A method is proposed for correcting probe measurements, which consists in the joint processing of two signals obtained in separate experiments with different surface areas of the double probe negative electrode and other conditions being equal. Using this method, the ion current and the change in the space potential are determined. The ion current, determined by the concentration of charged particles, remains unchanged until the shock wave arrival to the measurement point.
Criteria of computational grid generation for turbulence models taking into account laminar-turbulent transition
Authors: Matyushenko A A , Stabnikov A S , Garbaruk A V
Published: December 2019

Criteria of structured and unstructured mesh generation for turbulence models taking into account laminar-turbulent transition were developed using flat plate boundary layer flow. It is shown the first near wall cell should be placed in the viscous sublayer in the transition region and stretching factor should not exceed 1.4. For the unstructured meshes all the boundary layer should be covered by prismatic layers. The results of the prediction of the flow around a NLF(1)-0414F airfoil show that the use of relatively coarse meshes provide acceptable accuracy of the solution.
Peculiarities of the magnetic field distribution in the railgun channel
Authors: Popov Pavel , Poniaev Sergey , Kurakin Roman , Tverdokhlebov Konstantin , Reznikov Boris
Published: December 2019

The measurement of the magnetic field induction in the railgun channel was carried out. The influence of the conductivity of the rail material on the efficiency of magnetic field generation using external coils was evaluated. The distribution of the pulsed magnetic field corresponding to the experimental conditions is calculated. The evaluation of the applicability of the used model for the simulation of railgun for various types of boundary conditions in the passive circuit was carried out.
Effect of thermal modification of saponite-containing material on energy properties of its surface
Authors: Drozdyuk T A , Ayzenshtadt A M , Frolova M A
Published: December 2019

Preliminary experimental studies have shown the fundamental possibility and feasibility of using saponite-containing material (SCM), extracted from the pulp of the tailings dump of industrial enrichment of ores of the diamond deposit named after M.V. Lomonosov, as a mineral binder for mineral wool insulation. The technology of the production of mineral wool composite was based on the effect of high temperatures (up to 1200 °C) on the raw mix consisting of SCM as a binder and basalt fibers as a fibrous aggregate. However, the new properties of the saponite-containing material after thermal modification have not been investigated. Therefore, in this study, we studied the effect of the temperature of modification of the saponite-containing material on the criterion for evaluating the energy properties of the surface (the Hamaker constant). The experiments have shown that the maximum value (2.78·10−20 J) of the Hamaker constant is observed in the modification temperature range from 100 to 200 °C, then a decrease in the value of this criterion to a temperature of 600 °C is observed, and, there is a stabilization of the Hamaker constant in the range of temperatures from 700 °C to 1000 °C, the average value of which was 1.23·10−20 J.
Wire-free method of measurements of weak electrostatic values under stationary and dynamic conditions
Authors: Makhmudov Kh F
Published: December 2019

Usage of a developed and updated electrometer (EM) allows one, first, to obtain new information on physical properties of materials (glasses and other solids) as well as on the manifestation of the properties in the field of mechanical forces. Second, the applicational significance of such researches could be also important when designing new nondestructive methods of material defects controlling and procedures of their removal. The EM is up to measure both slowly and rapidly varying electric potentials at some distance from a target. EM allows one measure relaxation times of charges in dielectrics, which do not exceed the time constant of discharge time of the amplifier under stationary conditions. Owing to the developed scheme of the EM input circuit, the input capacity of amplifier was decreased with a corresponded increase of its sensitivity.