bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fractal-like frontier structure of avalanches in a sandpile model
Authors: Buzykin A G , Kuznetsov I A , Ipatov A N , Parshin D A 
Published: December 2020

Abstract
The self-organized criticality (SOC) phenomena for dynamical systems with spatial degrees of freedom is commonly observed in application to different aspects of natural sciences. In our study we also consider our sandpile model as such a system. Since the first mention in 1987, a sandpile model, which is a common example of spatiotemporal evolution, became widely applied for avalanche-like processes. With a simple computer simulation we show that an avalanche as a result of natural system evolution has a fractal border structure, and approves SOC phenomena of a sandpile model. We also demonstrate Gutenberg-Richter dependence for avalanche process in a sandpile model.
Comparative analysis of the optical and physical properties of InAs and In0.8Ga0.2As quantum dots
Authors: Salii R A , Mintairov M A , Mintairov S A , Nadtochiy A M , Kalyuzhnyy N A 
Published: December 2020

Abstract
Heterostructures with embedded layers of single InAs and In0.8Ga0.2 As quantum dots (QDs) in a GaAs matrix have been obtained by metalorganic vapor-phase epitaxy. The photoluminescence spectra of these QDs have been measured in a wide temperature range and the analysis of the photoluminescence peaks behavior has been carried out. As a result, it have been found that the In0.8Ga0.2 As QDs has better size uniformity and contains a smaller number of defective islands in comparison with InAs QDs.
Influence of carbon in the sp1 hybridized state on the structure of PbSe thin films
Authors: Razina A G , Kazakov V A , Ashmarin A A , Kochakov V D , Balobanov R N 
Published: December 2020

Abstract
The optical reflection spectra of PbSe films and PbSe films coated with a layer of linear chain carbon were studied by IR Fourier spectroscopy in the wavelength range of 1-16 μm. In all IR spectra of the samples, two minima were observed, related to plasma fluctuations of free charge carriers and related to the PbSe and PbSeO3 phases. It was found that the PbSe film coated with a layer of linear chain carbon is less oxidized. This conclusion is confirmed by the results of x-ray structural studies of the samples. The results showed a decrease in the percentage of oxygen-containing phase PbSeO3 by 2-4 times.
Features of formation of Langmuir monolayers of porphyrin derivatives on the surface of aqueous solutions of copper nanoparticles
Authors: Begletsova N N , Mironyuk V N , Ezhov A V , Smirnova A I , Usol’tseva N V , Glukhovskoy E G 
Published: December 2020

Abstract
Meso-aryl-substituted porphyrin monolayers were obtained by the Langmuir method depending on the aliquots applied to the water surface and the composition of the subphase. Regardless of the composition of the subphase (pure water or a solution with copper nanoparticles stabilized by surfactant) porphyrin compression isotherms showed the formation of monolayers until a film collapse state is reached. The presence in the subphase volume of copper nanoparticles stabilized by a surfactant (sodium dodecyl sulfate) contributed to the formation of a more stable porphyrin monolayer. A significant difference in the values of the surface potential at the end of porphyrin monolayer compression depending on the composition of the subphase is established. This fact is very promising in the context of creating film heterostructures with improved operational properties.
The effect of anodization current density on the functionalization of porous silicon nanoparticles with an antibiotic
Authors: Sattorov M Sh , Spivak Yu M , Gavazyuk N O , Panov M F 
Published: December 2020

Abstract
The influence of the anodization current density to the morphology and composition of the surface of porous silicon before and after its impregnation with an antibiotic was investigated using atomic force microscopy and IR spectroscopy. Layers of porous silicon were obtained by electrochemical etching; variable technological parameters of anodizing were the current density and the type of conductivity of the silicon plate. The results obtained are discussed in terms of their use in targeted drug delivery.
Study on the parameters of the microporous structure of zeolite compositions by sorption analysis methods
Authors: Maraeva E V , Kononova I E , Adamovich D S , Tokmeilova S , Skornikova S A , Moshnikov V A 
Published: December 2020

Abstract
The work is devoted to the study on the influence of various factors on the microporous structure parameters of the zeolite compositions being formed. To study the parameters of the microporous structure, sorption analysis methods were used. Zeolites of the BETA type and compositions based on them were chosen as objects under study. It was found that the formation of zeolite compositions is greatly influenced by the nature of the binder (matrix) and peptizer, which determine the proportion of micropores in the zeolite composition. It is shown that in the study of the textural characteristics of zeolite compositions, preliminary sample preparation (heat treatment to remove the moisture adsorbed by them) is necessary.
One-step electrochemical synthesis of Ag/por-Si composite from monocrystalline Si
Authors: Spivak Y M , Gagarina A Y , Portnova M O , Zaikina A V , Moshnikov V A 
Published: December 2020

Abstract
The technique of obtaining Ag/Por-Si composite material with homogeneously distributed silver nanoparticles over the surface of porous silicon by one cycle of electrochemical treatment of single-crystalline silicon. The effect is achieved by using an electrolyte to produce porous silicon with a special composition containing silver ions. During the electrochemical anode treatment of single-crystalline silicon in Ag-containing electrolyte a layer of porous silicon and silver islets are formed on the sample surface simultaneously. It is shown that the controlling the conditions of electrochemical processing provide an opportunity to form homogeneously distributed on the surface silver nanoparticles with a narrow-size distribution.
Structural and optical properties of quasi-2D GaTe layers grown by molecular beam epitaxy on GaAs (001) substrates
Authors: Avdienko P S , Kolyada D V , Firsov D D , Komkov O S , Sedova I V , Sorokin S V 
Published: December 2020

Abstract
Quasi-two-dimensional GaTe layers were grown by molecular beam epitaxy on GaAs (001) substrates at Ts
= 450–520°C. The effect of the growth temperature on the GaTe surface morphology has been studied by scanning electron microscopy. It is shown that GaTe layer grown at high Ts
= 520°C exhibits pronounced surface relief anisotropy. This sample demonstrates also near band-edge photoluminescence (PL) at T = 11K with the peak energy of ∼1.72 eV, which can be associated with the emission of excitons bound at the acceptor. The nature of 1.45 eV and 1.57 eV peaks appearing in the PL spectra is also discussed in detail.
Magnetization and electron spin resonance of a carbon/polymer composite
Authors: Ionov A N , Volkov M P , Semenikhin P V , Nikolaeva M N 
Published: December 2020

Abstract
It has been shown that in multilayer graphene/polystyrene composite, the static magnetization curve looks the same as in a type-II superconductor. The electron spin resonance in the same composite was studied as a function on temperature and magnetic field. The observed g-factor of 2.003 was independent of temperature and was in the range (g = 2.0022-2.0035) characteristic of a free carbon electron. This behavior of the g-factor excludes the appearance of an internal magnetic field in the composite.
Frequency shifts of the magnetic resonance of Rb and K atoms in the K-Rb tandem magnetometer
Authors: Kartoshkin V A 
Published: December 2020

Abstract
Collisions of alkali atoms in the ground state are accompanied by the exchange of electron polarization between the colliding atoms, which lead to the polarization transfer between particles. As a result of this process, the electronic orientation is transferred from the spin oriented atoms to unpolarized atoms, along with the polarization transfer, the magnetic resonance frequency shifts of polarized atoms occur too. In this work the magnetic resonance frequency shifts of arising from spin exchange collisions in a mixture of alkali potassium and rubidium atoms at the optical orientation of atoms are calculated. The situation when optical pumping by resonant polarized radiation is carried out only for atoms of the one kind is considered. The spin exchange process between alkali atoms was described in the formalism of the complex cross section for spin exchange process. The real and imaginary parts of the complex cross section were calculated using the interaction potentials of alkali atom dimers. The calculation of the frequency shifts is carried out on the basis of data on the interaction potentials for the following pairs of alkali atoms K-K, K-Rb and Rb-Rb. Maxwell averaging of the cross sections over the velocities was done and the temperature dependences of the magnetic resonance frequency shifts for K and Rb atoms were plotted.
Optical reflection spectra of resonant photonic structures based on a system of 100 InGaN quantum wells
Authors: Ivanov A A , Chaldyshev V V , Zavarin E E , Sakharov A V , Lundin W V , Tsatsulnikov A F 
Published: December 2020

Abstract
The optical reflectance and transmittance spectra of a periodic InGaN semiconductor heterostructure with 100 quantum wells are studied at room temperature. Numerical modeling with a single set of parameters gave a quantitatively accurate fit of the experimental reflection and transmission spectra in a wide wavelength range. The radiative decay parameter is determined to be 0.25 meV and the nonradiative decay parameter is 40 meV.
GaPN/GaP nanowire-polymer matrix: photoluminescence study
Authors: Koval O Yu , Fedorov V V , Bolshakov A D , Neplokh V V , Strom I V , Serov A Yu , Mukhin I S 
Published: December 2020

AbstractThis study is devoted to the investigation of the optical properties and composition of GaPN/GaP nanowire heterostructure. Nanowire arrays were grown on Si substrate (111) by the plasma-assisted molecular beam epitaxy. Polydimethylsiloxane membrane encapsulation was used to obtain the free-standing NW arrays. The morphology of GaPN/GaP NW was investigated with scanning electron microscopy. The optical properties of the GaPN nanowire arrays were determined at the He temperature (5K) with photoluminescence spectroscopy. Analysis of photoluminescence response allowed us to conclude that the incorporation of nitrogen atoms during the growth occurs both in the nanowires and in the parasitic islands with different content. Direct bandgap-like behaviour of the GaPN/GaP nanowires demonstrates the potential of nanowire-polymer matrix practical application in future optoelectronic devices.
Raman spectra of folded acoustic phonons in short-period GaN/AlN superlattices as a tool for structure characterization
Authors: Davydov V Yu , Roginskii E M , Kitaev Yu E , Smirnov A N , Eliseyev I A , Nechaev D V , Jmerik V N , Smirnov M B 
Published: December 2020

Abstract
The results of experimental and theoretical studies of phonon modes in short-period GaN/AlN superlattices grown by PA MBE on the (0001) Al2O3 substrate are reported. In the framework of Density Functional Theory and Elastic Continuum Model the lattice dynamics properties are studied of (GaN)m(AlN)n SLs (m+n≤24), where n and m are the number of monolayers. Good agreement between experiment and theory is found, which made it possible to establish unambiguously a relationship between the features observed in the Raman spectra and the microscopic nature of the acoustic phonon modes. The obtained results open new possibilities for analyzing the structural properties of GaN/AlN SLs by Raman spectroscopy.
Influence of Mach-Zehnder modulator bias point on chaotic dynamics in spin-wave optoelectronic oscillator
Authors: Kondrashov A V , Ustinov A B , Kalinikos B A 
Published: December 2020

Abstract
In this paper we investigate in details the scenario of a transition to chaos in the spin-wave optoelectronic oscillator. The feature of the investigated circuit is the presence of two nonlinearities with different nature – modulation instability of spin waves and nonlinearity of the transmission characteristic of the electro-optical modulator. The influence of a position of the modulator bias point on the scenario of chaos development is experimentally investigated.
Application study of ultra high frequency modulation of laser radiation for fiber-optic gyroscope noise reduction
Authors: Vostrikov E V , Smirnov D S , Nikiforovskii D A , Pogorelaya D A , Aleinik A S 
Published: December 2020

Abstract
Microwave photonics is implemented in many applications, including the area of inertial navigation systems based on high-precision fiber-optic gyroscopes. Microwave photonic technologies allow increasing the fiber-optic gyroscope accuracy. This paper investigates and evaluates the effect of ultra high frequency modulation of laser radiation on the closed-loop fiber-optic gyroscope output signal. Research results show that ultra high frequency modulation makes it possible to broaden spectrum width due to redistribution to modulation harmonics of the laser radiation. This approach allows to reduce the standard deviation of the laser-driven fiber-optic gyroscope output signal more than 2.5 times compared to using a laser-driven fiber-optic gyroscope without modulation. In order to achieve the noise level of a laser-driven fiber-optic gyroscope the same as the noise level of a fiber-optic gyroscope with a broadband source, it is necessary to use a broadband noise source with a constant power spectral density and higher output power. This study is useful for understanding how application of microwave photonic technologies can impact on the fiber-optic gyroscope output signal. The obtained results can be used for researchers in this area of study and can facilitate the rapid development of this field.
Time-frequency analysis of acoustic waves in an integrated acousto-optical modulator based on LiNbO3
Authors: Varlamov A V , Ivanov S I , Lavrov A P , Shamray A V 
Published: December 2020

Abstract
The work presents a method allowing calculating the input admittance of an acousto-optic modulator with XY-cut lithium niobate substrate for a specific interdigital transducer structure is presented. The method does not require complex numerical computations and is sufficiently accurate. The method is based on the information about the pole of a Green’s function for a given piezocrystal. A method of measuring parameters and finding the types of the excited acoustic waves based on joint time-frequency analysis using modern vector network analyzers is also presented. Good correlation between theoretical and experimental investigation is demonstrated.
Optically pumped non-zero field magnetometric sensor for the magnetoencephalographic systems using intra-cavity contacted VCSELs with rhomboidal oxide current aperture
Authors: Bobrov M A , Blokhin S A , Maleev N A , Blokhin A A , Vasyl’ev A P , Kuzmenkov A G , Pazgalev A S , Petrenko M V , Dmitriev S P , Vershovskii A K , Ustinov V M , Novikov I I , Karachinskii L Ya 
Published: December 2020

Abstract
We demonstrate the possibility of using vertical-cavity surface emitting lasers with intracavity contacts and a rhomboidal oxide current aperture for creating compact optically pumped 133Cs atomic magnetometer operating in non-zero magnetic fields, which is promising to use in magnetoencephalographic systems. The magnetic resonance parameters were studied in a two-beam MX optically pumped magnetic field sensor scheme based on the effect of the magnetic resonance line narrowing at high laser pumping and high concentrations of alkali-metal atoms. The ultimate sensitivity of OPM was estimated by the ratio of the magnetic resonance steepness to the probe light shot noise level. It is shown that a magnetic sensor based on the vertical-cavity surface emitting lasers and a compact (0.125 cm3 volume) Cs vapor cell can achieve a shot noise-limited sensitivity better than 15 fT in 1 Hz bandwidth. Developed intracavity contacted VCSELs suitable for use in compact atomic magnetometers for magnetoencephalographic systems.
Design of electrically driven single photon source based on dielectric passive cavity structure at 1.3 μm
Authors: Blokhin S A , Bobrov M A , Maleev N A , Blokhin A A , Vasyl’ev A P , Kuzmenkov A G , Shchukin V A , Ledentsov N N , Reitzenstein S , Ustinov V M 
Published: December 2020

Abstract
A combination of advanced concepts is applied for designing micro-cavity structures aimed for single-photon sources with high photon-extraction efficiency in the telecom O-band at ~1.3 μm. The device design consists of a broad stop-band bottom distributed Bragg reflector (DBR), a top DBR formed in a dielectric micropillar with additional circular Bragg grating and a central dielectric passive cavity. This combination of photonic elements is compatible with electric carrier injection and provides overall photon-extraction efficiency of ~83% as shown by 3D finite-difference time-domain simulations.
Charge transfer mechanisms in multistructured photoelectrodes for perovskite solar cells
Authors: Vildanova M F , Nikolskaia A B , Kozlov S S , Shevaleevskiy O I 
Published: December 2020

Abstract
Here we introduce the research studies of perovskite solar cells with multistructured photoelectrodes based on very wide bandgap nanocrystalline materials. A series of solar cells with the device architecture FTO/c-TiO2/ZrO2(HfO2)/CH3NH3PbI3/Spiro-MeO-TAD/Au was fabricated and characterized. The results obtained demonstrate a successful possibility of PV application of the nanostructured oxide materials with bandgap values exceeding 5 eV. We propose a mechanism, which describes charge carrier transport at the interface of perovskite/multistructured photoelectrode.
Tuning of laser power converters efficiency by means of temperature
Authors: Shvarts M Z , Emelyanov V M , Malevskiy D A , Mintairov M A , Mintairov S A , Nakhimovich M V , Pokrovskiy P V , Salii R A , Kalyuzhnyy N A 
Published: December 2020

Abstract
The results of studying the InxGa1−xAs laser power converters with the indium percentage of 18% and of 23% are presented. In the mode of 1064 nm laser radiation conversion the photovoltaic parameters dynamics with raising temperature is discussed.
Study of Latex sphere mask dry etching in oxygen
Authors: Morozov I A , Vyacheslavova K A , Gudovskikh A S , Uvarov A V , Baranov A I , Kudryashov D A 
Published: December 2020

Abstract
Nanosphere lithography is well suited for quick and easy formation of ordered structures on the entire silicon wafer. After coating of close packed mask of spheres, they must be reduced in diameter. In various studies, the main method used for spheres diameter reducing is dry etching using capacitively coupled plasma (CCP) mode. In this paper, we present the possibility of spheres etching using inductively coupled plasma (ICP) mode, comparing the results obtained with CCP mode. A strong degradation of the spheres morphology was demonstrated at CCP mode, while the degradation effect was not sufficient using ICP mode. However, the effect of spheres migration over the silicon surface during ICP etching was observed. A preliminary thermal annealing of spheres allows one to avoid this effect. Finally, a technology of reducing the spheres size with minimal degradation and preserving the original spherical geometry was developed.
The spin-filtering properties in two coupled Rashba quantum rings
Authors: Smolkina M O , Popov I Yu , Blinova I V 
Published: December 2020

Abstract
The spin-dependent electron transport in two coupled quantum rings with Rashba spin-orbit interaction and magnetic flux was studied by using quantum graph approach. We show the dependence of spin-polarization on system parameters such as the Rashba coupling constant, the radius of the rings, the angles between the leads and the attachment point of the rings. The spin-polarization can be controlled and changed from -1 to +1 by using a magnetic flux. Also it was shown that this model is a limiting case of double Rashba quantum ring when the length of the middle lead between rings vanishes.
Irreversibility field and anisotropic δl-pinning in type II superconductors
Authors: Guryev V V , Shavkin S V , Kruglov V S 
Published: December 2020

Abstract
The article presents a brief generalization of our recent experiments confirming that “irreversibility field” in Nb-Ti superconducting tapes is determined by the inhomogeneity of superconducting properties. It is shown that the effect is a direct consequence of the so-called δl-pinning, i.e. pinning caused by local reduction of the electrons mean free path. Based on the understanding of the irreversibility field nature, an assessment of the individual pinning force is performed. Good agreement is obtained with the estimations performed in the framework of the Larkin-Ovchinnikov pinning model (LO), which is valid for magnetic field less than the irreversibility field. The competing model is considered which is also valid for field range below the irreversibility field - the anisotropic pinning model (APM). The comparison of the fundamental length scales introduced in the LO and APM models is given.
Magnetic circular polarization of photoluminescence of an inhomogeneous ensemble of colloidal nanocrystals
Authors: Smirnova O O , Golovatenko A A , Rodina A V 
Published: December 2020

Abstract
In this paper, we theoretically analyze the recombination and spin dynamics of excitons in an inhomogeneous ensemble of colloidal nanocrystals, which consists of several subensembles with different lifetimes and degrees of circular polarization of exciton photoluminescence (DCP). Each subensemble is described within a three-level model of interacting exciton states, including two excited states and a ground state. Various ratios of parameters, leading to a nontrivial time-dependent DCP and a difference in the integral and equilibrium DCP characteristics, are considered. It is shown that the presence of subensembles with different polarizations and lifetimes results in nonmonotonic dependence and a change in the sign of the DCP in magnetic field and as a function of time can occur. The theoretical model was implemented to describe the time dependences of the DCP in ensembles of colloidal CdSe nanoplatelets synthesized in the air and argon atmosphere.
Influence of a constant field on a circular photovoltaic effect in two-dimensional superlattices
Authors: Konchenkov V I , Myachkova A A , Zav’yalov D V 
Published: December 2020

Abstract
Using the relaxation time approximation, an analytical expression was obtained for the direct current density arising in a two-dimensional superlattice when, in addition to two elliptically polarized waves, a constant field acts on the sample along one of the directions.
Influence of doping profile of GaN:Fe buffer layer on the properties of AlGaN/AlN/GaN heterostructures for high-electron mobility transistors
Authors: Arteev D S , Sakharov A V , Lundin W V , Zavarin E E , Zakheim D A , Tsatsulnikov A F , Gindina M I , Brunkov P N 
Published: December 2020

Abstract
The effect of the Fe doping profile of the GaN buffer layer in the heterostructures for high-electron mobility transistors was studied experimentally and by computer simulation. The exponential Fe tail extending to the nominally undoped layers may greatly affect the properties of the structure. Reducing the distance between the channel and the Fe-doped buffer to less than 1 μm results in a decrease in the density and mobility of the two-dimensional electron gas. It also leads to the higher off-state avalanche breakdown voltage and reduced leakage current. A good agreement between simulation and experimental data is obtained when taking into account a Fe segregation effect, while an abrupt doping profile lead to significant discrepancies between them