bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin–Orbit Interaction in ZnO/MgxZn1 – xO Heterojunctions Probed by Electron Spin Resonance Spectroscopy
Authors: Khisameeva A. R , Shchepetil'nikov A. V , Dremin A. A , Kukushkin I. V
Published: April 2024

The spin–orbit interaction in a series of ZnO/MgxZn1 – xO heterojunctions containing a two-dimensional electron system with a wurtzite structure has been studied in detail. The spin–orbit coupling constants have been determined from the analysis of the modification of the single-particle g-factor caused by the spin–orbit interaction in the quantum Hall effect regime. The g-factor has been measured with high accuracy by the electron paramagnetic resonance technique in wide ranges of magnetic fields and electromagnetic frequencies. The spin–orbit coupling constants have been determined for a series of samples with different Mg concentrations, which has allowed us to obtain the dependence of the spin–orbit coupling constant on the two-dimensional electron density n. The measured spin–orbit coupling constant is in the range of 0.5–0.8 meV Å and quite weakly depends on n. The coefficients specifying the linear and cubic contributions to the spin–orbit interaction determined from the approximation of the experimental data are α0 = 0.48 meV Å and γ = 0.12 eV Å3, respectively. These values are correlated with results obtained by other research groups.
Chiral Separation Effect in a Quark–Gluon Plasma
Authors: Khaydukov Z. V
Published: April 2024

An expression for the chiral separation effect in a quark–gluon plasma has been derived using the method of field correlators by expanding in Landau levels.
Interaction Potential of Protons and Hydrogen Atoms with Metals
Authors: Babenko P. Yu , Mikhaylov V. S , Zinov'ev A. N
Published: April 2024

Approximate potentials for protons and hydrogen atoms in metals have been proposed. It has been shown that the difference between the interatomic interaction potentials obtained in the density functional theory for the gas phase and our potentials obtained by processing experimental data on the scattering of atomic particles from the surface of solids can be explained by including the screening of the charge of an incident particle. The effect of screening in the potential on the angular distributions of atomic particles passed through thin films and on nuclear stopping powers has been established.
Quasicrystalline Structures with Narrow-Band Frequency–Angular Selectivity
Authors: Chistyakov V. A , Sidorenko M. S , Sayanskiy A. D , Rybin M. V
Published: April 2024

Design methods in the reciprocal space allow one to obtain structures with desired properties. Quasicrystalline photonic structures, which ensure the selective scattering of an electromagnetic wave incident on the sample, have been designed. The maxima of the Fourier transform of the desired distribution of the permittivity in the reciprocal space are located along two arcs on the Ewald sphere, which corresponds to the scattering of the wave with the required wavelength and angle of incidence. The material distribution has been determined by the transition to the real space. A structure with a low dielectric contrast has been formed after the binarization of the refractive index. The theoretical analysis of the properties of the structure has confirmed the frequency–angular selectivity of scattering. The numerical calculations show the possibility of achieving the effective scattering and absorption of the electromagnetic energy up to 94% in a narrow frequency range and in a narrow interval of angles of incidence at a dielectric contrast of two materials of 1.07.
Density Functional Theory, Molecular Dynamics, and AlteQ Studies of Baimantuoluoamide A and Baimantuoluoamide B to Identify Potential Inhibitors of Mpro Proteins: a Novel Target for the Treatment of SARS COVID-19
Authors: Gurushankar K. , Jeyaseelan S. Ch. , Grishina M. , Sisvanto I. , Tiwari R. , Puspaningsih N. N.T
Published: April 2024

COVID-19 has resulted in epidemic conditions over the world. Despite efforts by scientists from all over the world to develop an effective vaccine against this virus, there is presently no recognized cure for COVID-19. The most succeed treatments for various ailments come from natural components found in medicinal plants, which are also crucial for the development of new medications. This study intends to understand the role of the baimantuoluoamide A and baimantuoluoamide B molecules in the treatment of Covid19. Initially, density functional theory (DFT) used to explore their electronic potentials along with the Becke3–Lee–Yang–Parr (B3LYP) 6-311 +basis set. A number of characteristics, including the energy gap, hardness, local softness, electronegativity, and electrophilicity, have also been calculated to discuss the reactivity of molecules. Using natural bond orbital, the title compound’s bioactive nature and stability were investigated. Further, both compounds potential inhibitors with main protease (Mpro) proteins, molecular dynamics simulations and AlteQ investigations also studied.
Emergent long-lived Zitterbewegung in Su–Schrieffer–Heeger lattice with third-nearest-neighbor hopping
Authors: Chen M. -N , Yu X. -J , Li Z.
Published: April 2024

We investigate the wavepacket dynamics of quasiparticles in a Su–Schrieffer–Heeger lattice with third-nearest-neighbor hopping. The results reveal that the life-span of Zitterbewegung can be prolonged. To better understand the mechanism, we discuss the band structure and the long-time average of inverse participation rate. The results show that the band structure can be effectively manipulated as a quasi-flat band by introducing the third-nearest-neighbor hopping. This, as a unique advantage over the standard Su–Schrieffer–Heeger model, will bring about restrained diffusion of the wavepacket as well as dramatically stretched life-span of Zitterbewegung, thus will promise wide applications in condensed matter physics.
Measurement of the T20 Component of the Tensor Analyzing Power of the Incoherent Photoproduction of a π– Meson on a Deuteron
Authors: Gauzshteyn V. V , Vasilishin B. I , Darvish E. , Zevakov S. A , Kuzin M. Ya , Kuz'menko A. S , Levchuk M. I , Loginov A. Yu , Nikolenko D. M
Published: April 2024

New results have been presented for the T20 component of the tensor analyzing power of the γd → ppπ– reaction measured in the photon energy range from 300 to 600 MeV. The data have been obtained from the statistical sample collected at the VEPP-3 accelerator in 2021. The T20 component has been separated using the asymmetry of the reaction yield, which is due to change in the sign of the tensor polarization of the deuterium target. The experimental data have been compared to the simulation within the spectator model including the interaction between particles in the final state.
Ultrathin GeTe Crystal in a Strong Femtosecond Laser Field: Manifestation of a Quantum Size Effect
Authors: Aseev S. A , Mironov B. N , Kochikov I. V , Lotin A. A , Ishchenko A. A , Ryabov E. A
Published: April 2024

The behavior of a thin-film GeTe crystal induced by intense femtosecond laser pulses (μm) has been studied using a pulsed electron diffractometer. The sample is an annealed 20-nm GeTe film on a copper grid with a carbon coating. It has been found that laser ablation results in the formation of an ultrathin GeTe crystal (assumingly, GeTe monolayer) with a high radiation resistance. Possible reasons for the detected nanosize effect are discussed.
Designing the Structure of a One-Dimensional Photonic Crystal with a Given Spectrum of the Reflection Coefficient
Authors: Emel'yantsev P. S , Pyshkov N. I , Svyakhovskiy S. E
Published: April 2024

A method for solving the inverse problem of designing the structure of a one-dimensional photonic crystal is proposed and experimentally implemented. It is known that a one-dimensional photonic crystal with a spatial sinusoidal modulation of the refractive index, has a narrow photonic bandgap at a frequency related to the spatial frequency of this sinusoid. A reverse engineering method is proposed for one-dimensional photonic crystals with an arbitrary given reflection spectrum by expanding this spectrum into elementary photonic band gaps and then summing them. The application of this method to fabricate examples of photonic crystals with simple shapes of spectral reflection curves is demonstrated.
Mysteries of Water and Other Anomalous Liquids: “Slow” Sound and Relaxing Compressibility and Heat Capacity (Brief Review)
Authors: Brazhkin V. V , Danilov I. V , Tsiok O. B
Published: April 2024

Reasons for the existence of “fast” sound at terahertz frequencies in various liquids have been analyzed. It has been shown that the fast sound speed is described well by the conventional formula from the theory of elasticity, where ρ is the density of a liquid andandare the bulk and shear moduli at the frequency ω, respectively. The excess of the speed of fast sound over the speed of normal sound in “normal” liquids is 10–20% and is almost completely determined by the contribution of the shear modulusat high frequencies, and vanishes on the Frenkel line. At the same time, the huge excess (50–120%) of the fast speed of sound over the speed of normal sound in some liquids (called “anomalous”), such as water and tellurium melt, is due mainly to the strong frequency dependence of the bulk modulus. Anomalously low relaxing bulk moduli were studied in our previous works for many oxide and chalcogenide glasses near smeared pressure-induced phase transitions. In anomalous liquids, smeared phase transitions also occur in a wide temperature and pressure region, which sharply reduces the bulk moduli and speeds of sound. Thus, the record large difference between speeds of fast and normal sound in anomalous liquids is due not to anomalously fast sound but to the fact that normal sound in such liquids is anomalously “slow” and bulk moduli are anomalously low. Ultrasonic studies of low- and high-density amorphous water ices show that their bulk moduli are indeed a factor of 4–5 higher than the bulk modulus of water. In addition, because of smeared phase transitions, the heat capacities of water and tellurium melt are a factor of 1.5–2 higher than those for normal liquids; i.e., anomalous liquids are characterized not only by an anomalous (nonmonotonic) behavior but also by anomalous magnitudes of physical quantities for most of the available measurement methods. A similar anomalous increase in the compressibility and heat capacity is observed for all fluids in the close vicinity of the liquid–gas critical point. In this case, anomalously fast sound is observed at terahertz frequencies, which is also due to a sharp increase in the bulk modulusat high frequencies. At the same time, high compressibility and heat capacity, as well as a large excess of the speed of fast sound over the speed of normal sound, for anomalous liquids and glasses near smeared phase transitions are not necessarily due to the proximity of critical points and occur in any scenario of the smeared phase transition.
Use of a Fluorescent Dye for Controlling the Laser Absorption in the Femtosecond Laser Nanosurgery of Cells
Authors: Martirosyan D. Yu , Osychenko A. A , Zalesskiy A. D , Kalinina O. T , Tochilo U. A , Fedotov Yu. A , Syrchina M. S , Nadtochenko V. A
Published: April 2024

The use of specific fluorescent dyes is able to reduce the labeled cell structure ionization threshold under the femtosecond laser impact. This feature may be applied in terms of the laser nanosurgery of the cell. In this work we use BioTracker Blue dye as a photosensitizer in order to receive an accurate control of cytoplasmic membrane ablation by femtosecond laser and to relief the laser-induced cell fusion. We have found that BioTracker Blue (366/441) increases an efficiency of the 760 and 730 nm laser absorption. However, an increase of absorption efficiency, provided by the BioTracker Blue staining, did not improved the efficiency of the cell fusion in the model systems: pairs of suspended A549 cells, oocytes and their polar bodies, and two-cell embryos.
Gluon Anomaly and the Violation of the Zweig Rule
Authors: Osipov A. A
Published: April 2024

It is well known that the gluon anomaly is responsible for the mass of the U(1) Goldstone boson. It is also manifested in the properties of pseudo-Goldstone states: the gluon anomaly in the next order of the 1/Nc expansion induces interactions violating the Zweig rule. A necessary condition for this is the explicit breaking of the chiral symmetry by the masses of light quarks. One of the physical consequences is that the η–η' mixing does not affect theamplitude. Another consequence is the suppression of the first 1/Nc correction to the η–η' mixing angle. The mechanism of such suppression is discussed in detail. The conclusions are based on the 1/Nc expansion and the effective meson Lagrangian of the Nambu–Jona-Lasinio model and are compared with the results of the 1/Nc chiral perturbation theory.
Inclusion of the Energy Distribution of Free Carriers in the Rate Equations Describing Their Dynamics at the Interaction of Dielectrics with Intense Laser Radiation
Authors: L'vov K. V , Stremoukhov S. Yu
Published: April 2024

The dynamics of free carriers in CaF2 induced by intense femtosecond radiation of the near- (1.24 μm) and mid- (4.4 μm) infrared ranges has been studied. It has been shown that the energy distribution of carriers formed after the passage of a laser pulse with a fluence sufficient for active impact ionization has a shape independent of the parameters (fluence, duration, and wavelength) of laser radiation and the width of the band gap of the material. The mean kinetic energy of free carriers after the action of the pulse is 0.56 of the width of the band gap. The inclusion of the dispersion term in rate carrier dynamics models makes it possible to reduce the difference of the mean kinetic energy from the statistical Fokker–Planck model by 30%. The application of rate carrier dynamics models instead of statistical models requiring large time and computational resources allows one to accelerate calculations by a factor of 20.
Energy Spectrum of the Valence Band in HgTe Quantum Wells on the Way from a Two- to Three-Dimensional Topological Insulator
Authors: Min'kov G. M , Rut O. E , Sherstobitov A. A , Dvoretskiy S. A , Mikhaylov N. N , Aleshkin V. Ya
Published: April 2024

The magnetic field and temperature dependences of longitudinal magnetoresistance and the Hall effect have been measured in order to determine the energy spectrum of the valence band in HgTe quantum wells with the width dQW = 20–200 nm. The comparison of hole densities determined from the period of Shubnikov–de Haas oscillations and the Hall effect shows that states at the top of the valence band are doubly degenerate in the entire dQW range, and the cyclotron massdetermined from the temperature dependence of the amplitude of Shubnikov–de Haas oscillation increases monotonically fromto(is the mass of the free electron) with increasing hole densityfromtocm–2. The determined dependence has been compared to theoretical dependencescalculated within the four-band kP model. These calculations predict an approximate stepwise increase inowing to the pairwise merging of side extrema with increasing hole density, which should be observed atand 4 × 1010 cm–2 for dQW = 20 and 200 nm, respectively. The experimental dependences are strongly inconsistent with this prediction. It has been shown that the inclusion of additional factors (electric field in the quantum well, strain) does not remove the contradiction between the experiment and theory. Consequently, it is doubtful that the mentioned kP calculations adequately describe the valence band at all dQW values.
Zavisimost' skorosti relaksatsii kogerentnykh sostoyaniy ot chisla Dependence of the Relaxation Rate of Coherent States on the Number of Correlated Spins and the Order of Coherence
Authors: Zobov V. E , Lundin A. A
Published: April 2024

The relaxation of the components of the multiple-quantum NMR spectrum of a solid under the effect of the dipole–dipole interactions during the evolution period is considered. It is taken into account that clusters of dynamically correlated spins of different sizes are formed in the preparatory period, and their degradation depends on their size and coherence order. To calculate the size distribution function of clusters and their degradation function, a physical model including relaxation processes is developed. Using this model, an analytical result for a multiple-quantum spectrum is obtained. Agreement is obtained between the theoretical and experimental dependences of the coherence degradation rates in adamantane scaled by the square root of the average cluster size. The parameters of the above functions are found from the comparison of these dependences.
Giant Spatial Redistribution of Electrons in a Wide Quantum Well Induced by Quantizing Magnetic Field
Authors: Dorozhkin S. I , Kapustin A. A , Fedorov I. B , Umanskiy V. , Smet Yu. Kh
Published: April 2024

In samples of field-effect transistors based on GaAs/AlGaAs heterostructures with an electron system in a single 50-nm-wide GaAs quantum well, a transition stimulated by a quantizing magnetic field has been detected from a bilayer state of the system in zero magnetic field to a single-layer state when only the lowest Landau level is filled. In contrast to the results for the 60-nm-wide quantum well obtained in [S. I. Dorozhkin, A. A. Kapustin, I. V. Fedorov, V. Umansky, and J. H. Smet, Phys. Rev. V 102, 235307 (2020)], the single-layer state is observed not only in incompressible quantum Hall effect states of the electron system at filling factors of 1 and 2, but also in compressible states between these filling factors. The spatial location of the single-layer system in the quantum well has been established; it appears to be independent of the electron distribution over the layers in a low magnetic field. A possible qualitative explanation for this observation has been proposed. The detected transition is supposedly due to the negative compressibility of two-dimensional electron systems caused by exchange-correlation contributions to the electron−electron interaction.
Memory Effects in the Nonequilibrium Critical Behavior of the Two-Dimensional XY Model in the Low-Temperature Berezinskii Phase
Authors: Popova A. P , Popov I. S , Chemeris S. P , Prudnikov V. V , Prudnikov P. V
Published: April 2024

The Monte Carlo study of nonequilibrium memory effects in the two-dimensional pure and structurally disordered XY model in the low-temperature Berezinskii phase has been performed. Features of the correlation between memory and aging effects have been demonstrated. A qualitatively novel phenomenon for memory effects has been revealed: dynamic curves of the autocorrelation function in the thermal cycling time interval tend to the dynamic curves with the initial temperature. A unique implementation of memory effects has been demonstrated at both cooling and heating cycling of the system under the condition that cooling and heating temperatures are in the low-temperature Berezinskii phase. The influence of structural disorder on memory effects has been analyzed. It has been found that they are enhanced in the structurally disordered system owing to the enhancement of aging effects.
Programmable Shaping of Femtosecond Pulses Using a One-Dimensional Photonic Crystal with Continuous Spatial Modulation of the Refractive Index
Authors: Svyakhovskiy S. E.
Published: April 2024

An algorithm for constructing the structure of a one-dimensional photonic crystal, which forms a femtosecond pulse of an arbitrary given shape when reflecting a Gaussian pulse, is developed theoretically. The method is illustrated by the example of a rectangular pulse. Examples for simple pulse shapes are given, the influence of optical absorption is evaluated, and a method for its compensation is proposed.
Dependence of Resonant Light Wavefront Reversal on Polaritons on the Optical Pump Intensity in Zinc Oxide Films
Authors: Gruzintsev A. N.
Published: April 2024

The possibility of resonant light wavefront reversal in an excited semiconductor medium has been demonstrated theoretically and experimentally. Induced light wavefront reversal in the infrared spectral range equal to half the energy of the radiative recombination of polaritons has been detected on epitaxial ZnO films under nitrogen laser pumping at room temperature. Dependences of the intensity of the wavefront reversal signal on the energy of the incident photon and the laser pump intensity have been examined.
Plasma Excitations in SiGe/Si Quantum Wells
Authors: Khisameeva A. R. , Shchepetil'nikov A. V. , Nikolaev G. A. , Lopatina S. A. , Fedotova Ya. V. , Kukushkin I. V.
Published: April 2024

Plasma and magnetoplasma excitations in high-quality undoped two-dimensional electron systems based on SiGe/Si quantum wells are studied in detail. A two-dimensional electron system is formed by applying a vo-ltage to the top gate, which is partially transparent to subterahertz radiation in the frequency range of 20‒160GHz. The results for SiGe/Si quantum wells with a Sb δ-doping layer are also presented for comparison. The transport and quantum scattering times for both structures are directly determined. It has been found that the effective electron mass is almost independent of the two-dimensional electron density in a wide density range.
Plasmons in a Strip with an Anisotropic Two-Dimensional Electron Gas Fully Screened by a Metal Gate
Authors: Rodionov D. A. , Zagorodnev I. V.
Published: April 2024

Interest in anisotropic two-dimensional electron systems and in plasma oscillations in them has been growing recently. Plasmons in a strip with a two-dimensional electron gas with an elliptic Fermi surface that is located near a metal gate, which screens the fields of the two-dimensional gas, have been theoretically analyzed. The plasma eigenmodes in this system have been found analytically in the limit of strong screening and the frequencies and damping rates of these modes have been determined taking into account anisotropy, magnetic field, and electromagnetic retardation effects. It has been shown that the fundamental mode in this limit is an edge magnetoplasmon with a linear dispersion relation. The frequency, damping rate, and velocity of this magnetoplasmon are independent of the magnetic field, and the localization length near the edge is proportional to the magnetic field. The square of the frequency of any other mode is the sum of the square of the frequency of this plasma mode without magnetic field and the square of the cyclotron frequency with a coefficient, which is independent of the orientation of the conductivity tensor with respect to the edges of the strip but depends on the principal values of the effective mass tensor when electromagnetic retardation effects are taken into account.
Topological Memory with Multiply-Connected Planar Magnetic Nanoelements
Authors: Metlov K. L.
Published: April 2024

A coding scheme is introduced to store a set of linked bit strings in planar magnetic nanoelements with holes. Analytical expressions for the corresponding magnetization distributions are developed up to a homotopy and the specific examples are given for doubly- and triply-connected cases. The energy barriers, protecting the information-bearing states, are discussed. Compared to a set of disparate simply-connected nanoelements of the same total connectivity, the nanoelements with holes can hold much more information due to the possibility of linking the individual bits.
Photoinduced Nonthermal Reduction of the Coercive Field in FePt and FePt0.84Rh0.16 Epitaxial Thin Films in the L10 Phase
Authors: Petrov A. V. , Nikitin S. I. , Tagirov L. R. , Kamzin A. S , Yusupov R. V
Published: April 2024

The time-resolved magneto-optical Kerr effect in epitaxial thin films of the FePt compound and the FePt0.84Rh0.16solid solution with the perpendicular magnetic anisotropy on MgO (001) substrates has been studied. The evolution of hysteresis loops at short (100 fs–1 ns) and long (1–20 ms) time scales after the excitation by a femtosecond light pulse has been studied. Long-lived nonthermal reduction of the coercive field has been detected. The coercive field is recovered in several milliseconds. It has been proposed to explain the observed phenomenon by the excitation of high-Q-factor acoustic resonances in the substrate/film system and to the strong magnetoelastic interaction in FePt and FePt0.84Rh0.16films.
Memory Effects in the Magnetoresistance of Two-Component Electron Systems
Authors: Denisov K. S. , Baryshnikov K. A. , Alekseev P. S.
Published: April 2024

The theory of the magnetotransport in a two-component electron system with rare macroscopic defects has been developed. In such a system, the classical memory effects in the scattering of electrons by defects and a slow transfer of electrons between the components of the liquid occurring due to the electron–electron scattering play a decisive role. It has been shown that the flow regime depends on the ratio of the sample width to the characteristic internal length, which is determined by the rate of electron transfer between the components. In samples wider than the internal length, the flow of the two-component liquid as a whole is formed within the bulk of the sample and is described by the corresponding Drude formulas taking into account memory effects. In this case, the magnetoresistance is positive at low magnetic fields and negative at high fields. In samples narrower than the characteristic length, the transfers involving a change in the type of electrons do not provide enough time to form a unified liquid. As a result, the flows of different components are independent and described by their own conductivities, taking into account the memory effects, while the magnetoresistance is strictly negative.
Cascade Formation of Topological Defects and Satellite Droplets in Liquid Crystals at Dynamic Capillary Instability
Authors: Dolganov P. V. , Spiridenko N. A. , Dolganov V. K. , Kats E. I. , Baklanova K. D.
Published: April 2024

The formation of topological defects at the nematic–isotropic liquid interface and near satellite droplets has been detected at the breakup and fragmentation of the bridge of the isotropic phase between nematic domains. This process has been implemented in thin optical cells filled with a liquid crystal. The critical width of the bridge at which a universal time dependence of its width is determined by the capillary velocity (ratio of the surface tension to the viscosity) has been determined.
Sizes of the Neutron–Proton Halo in Nucleon-Stable States of the 6Li Nucleus
Authors: Rodkin D. M. , Chuvil'skiy Yu. M.
Published: April 2024

The matter, neutron, and proton radii of nucleon-stable 1+and 0+states of the6Li nucleus are studied theoretically within the no-core shell model. The results have been comparatively analyzed with the radii of the 0+state of the6He nucleus. To increase the accuracy of calculations, we have developed an extrapolation procedure. A new definition of the quantitative measure has been proposed and justified to describe the properties of a halo formed by loosely bound neutrons and protons in theA-nucleon problem. The sizes of the halo in the indicated states of6Li have been calculated for the first time. It has been demonstrated that the sizes of their halos are close to those of the two-neutron halo in6He. Thus, additional reliable evidence of the existence of the neutron–proton halo in the discussed states of6Li has been obtained.
General Thermodynamic Approach to Describe the Kinetics of Thermal Effects in High-Entropy Metallic Glasses
Authors: Makarov A. S.
Published: April 2024

A method is proposed to calculate thermal effects induced by the heat treatment of high-entropy metallic glasses within the general thermodynamic approach. The experimental verification of the proposed method shows that the exothermic effect observed below the calorimetric glass transition temperature, the endothermic effect in the glass transition region, and the exothermic effect during the crystallization of a metallic glass can be quantitatively described using the general thermodynamic equation for the change in the entropy of the glass including the diaelastic effect.
Spin States of Cobalt Ions in the Bulk and on the Surface of LaCoO3 Probed by X-ray Absorption, Emission, and Photoelectron Spectra
Authors: Galakhov V. R. , Udintseva M. S. , Smirnov D. A. , Makarova A. A. , Kyupper K.
Published: April 2024

We present X-ray photoelectron, CoL2,3and OKX-ray absorption, as well as CoKβ1,3X-ray emission spectroscopy results of studies of the spin states of trivalent cobalt ions in single-crystal cobaltite LaCoO3. We show that at room temperature, in the bulk of a LaCoO3single crystal, Co3+ions are in the low-spin state, while high-spin Co2+, high-spin Co3+, low-spin Co3+, and probably also intermediate-spin Co3+ions are located on the surface.
Optimization of Adiabatic Superconducting Logic Cells by Using π Josephson Junctions
Authors: Khismatullin G. S. , Klenov N. V. , Solov'ev I. I.
Published: April 2024

Adiabatic superconducting logic circuits can ensure the practical implementation of operations with the energy dissipation below the Landauer limit. However, applications of the existing solutions are limited because of two contradictory requirements of a high energy efficiency and a sufficiently fast response of devices. Josephson junctions with a negative critical current (π junctions) allow one to obtain a certain form of the potential energy of superconducting circuits and, as a result, a practically required degree of control of dynamic processes in the proposed reversible logic cells. The features of the current transport and balance of Josephson phases in circuits with π junctions make it possible to improve the coupling between the parts of a reversible computer by a factor more than 2. At the same time, the continuous evolution of the state is ensured at higher critical currents and higher characteristic voltages of the main Josephson junctions of adiabatic superconducting logic cells, which allows an increase in the response rate.
Probability of High Intensities of the Light Wave Propagating in a Turbulent Atmosphere
Authors: Kolokolov I. V. , Lebedev V. V.
Published: April 2024

We examine statistics of fluctuations of the laser beam intensity at its propagating in turbulent atmosphere. We are interested in relatively large propagating distances and the remote tail of the probability density function. The tail is determined by the stretched exponent, we find its index.
Manifestation of “Slow” Light in the Photocurrent Spectra of Ge/Si Quantum Dot Layers Combined with a Photonic Crystal
Authors: Yakimov A. I. , Kirienko V. V. , Dvurechenskiy A. V. , Utkin D. E.
Published: April 2024

The spectral characteristics of the photocurrent in the near-infrared range in vertical Ge/Sip–i–nphotodiodes with Ge quantum dots embedded in a two-dimensional photonic crystal are investigated. The interaction of the quantum dots with photonic Bloch modes leads to the resonant enhancement of the sensitivity of photodiodes. The dependences of the photocurrent on the angle of incidence of light are used to determine the dispersion relations of the Bloch modes. Regions in the dispersion characteristics where the group velocity of photons is close to zero are revealed. It is established that the maximum enhancement of the photocurrent relative to a photodiode without photonic crystal, which can be up to a factor of ~60, results from the interaction of quantum dots with “slow” Bloch modes.
Giant Raman Scattering on Plasmon Metal Surfaces as a Method to Control Their Functional and Supramolecular Structural Characteristics
Authors: Kovalets N. P. , Razumovskaya I. V. , Bedin S. A. , Naumov A. V.
Published: April 2024

Fundamentals of surface-enhanced Raman spectroscopy/scattering have been developed and possibility of its application to analyze some structural characteristics of surfaces and agglomerates of plasmonic metal nanostructures has been considered. A remote nondestructive express method based on surface-enhanced Raman spectroscopy has been presented to control the degree of local cracking of a metal coating and the effect of defects/cracks on the conductivity of a thin metallized film (uniaxially stretched polyethylene terephthalate track-etched membrane with a 50-nm silver coating).
Effect of “Refraction” of Magnetic Domain Boundaries at Electrical Inhomogeneities
Authors: Podkletnova A. A. , Kolyushenkov M. A. , Myasnikov N. V. , Nikolaeva E. P. , Kaminskiy A. S. , Nikolaev A. V. , Pyatakov A. P.
Published: April 2024

A magnetoelectric effect, which manifests itself as a “refraction” of domain walls at the location of an electrode deposited on the surface of an iron garnet film, is studied. The “refractive index” depends on the electric voltage applied to the electrode and varies from 0.6 to 1.2. An electrically induced change in the surface energy of a domain wall due to an inhomogeneous magnetoelectric coupling is suggested as the mechanism of this effect.
High Harmonic Generation near the Low-Frequency Edge of a Plateau under Nonlinear Propagation of 1.24-μm Near-Infrared Femtosecond Laser Radiation in a Dense Argon Jet
Authors: Rumyantsev B. V. , Pushkin A. V. , Potemkin F. V.
Published: April 2024

High (15–25) harmonic generation in the vacuum ultraviolet spectral range (83–50 nm) has been realized by focused (NA = 0.033) near-infrared femtosecond laser radiation (wavelength λ = 1.24 μm) with a vacuum intensity of ~7.5 × 1014W/cm2irradiating a dense gas jet. It has been shown experimentally that the use of such a high-numerical aperture focusing requires high (up to 10 bar) gas jet pressures to optimize phase matching. The use of the dense gas jet results in a noticeable manifestation of nonlinear propagation effects for generating radiation, which affect the generation process through the change in the phase matching conditions. Furthermore, it has been shown that the prechirping of the generating pulse makes it possible to compensate a chirp appearing due to self-phase modulation and to increase the harmonic generation efficiency because of the nonlinear compression of the generating pulse. This approach has allowed 17th (73 nm) harmonic generation with an energy of 2 pJ in a pulse and a generation efficiency of 5.4 × 10–9. The estimates obtained have shown that this radiation can be used for single-pulse maskless photolithography in the extreme ultraviolet range.
Second Harmonic Generation as a Noninvasive Method to Study Molecular Processes on the Surface of Lipid Membranes (Brief Review)
Authors: Eremchev M. Yu.
Published: April 2024

The development and implementation of modern experimental methods in interdisciplinary projects promote the solution of fundamental problems in molecular biology and medicine. One of these problems is the understanding of the physics of molecular interactions in a narrow (1 nm) surface layer of cellular lipid membranes (hydration layer of the membrane), where most of the important electrochemical interactions with ions and proteins, transmembrane transport of molecules, and endocytosis occur. The solution of this problem requires noninvasive methods sensitive to changes in the molecular structure of the surface layer of membranes. The aims of this work are to describe advantages of nonlinear optical microscopy and spectroscopy for the study of structural and electrostatic features of lipid membranes, to present the developed method for the visualization of the hydration of lipid membranes, and to discuss the limits of applicability of this method.
Polarization Dynamics of Narrow Spectral Modes of a Random Distributed Feedback Raman Fiber Laser
Authors: Vatnik I. D. , Gorbunov O. A. , Churkin D. V.
Published: April 2024

The polarization properties of narrow spectral modes appearing in a Raman fiber laser with random distributed feedback due to Rayleigh backscattering near the lasing threshold have been studied experimentally. It has been shown that the modes have a high degree of polarization and that the polarization states of simultaneously generated modes are weakly correlated.
Magnetic Structure and the Spin-Crossover Mechanism in Ludwigite Со3BO5
Authors: Zamkova N. G. , Zhandun V. S. , Ovchinnikov S. G.
Published: April 2024

A spin-crossover mechanism in ludwigite Со3BO5is proposed on the basis of the DFT calculation with SCAN potentials. The role of separate exchange interactions in the establishment of the long-range magnetic order is demonstrated within the Monte Carlo method.
Interplay between Magnetism and Topology in MnBi2Te4
Authors: Val'kov V. V. , Zlotnikov A. O. , Gamov A.
Published: April 2024

The dependence of the topology of the fermion excitation spectrum on the magnetic state of the system is analyzed taking into account the structure of the Te–Mn–Te trilayer in the Te–Bi–Te–Mn–Te–Bi–Te layer sequence of the MnBi2Te4van der Waals single crystal, crystal field effects, spin–orbit coupling, and the covalent mixing of electronic states of Mn2+ions with electronic states of Te2–ions in the strong electron correlation regime. The Chern number in the ferromagnetic phase, which is due to the kinematic interaction between Hubbard fermions, is equal to 1; i.e., the topology of the band structure of the Te–Mn–Te trilayer is nontrivial. The Chern number in the paramagnetic phase is zero; i.e., the topology is trivial. The magnetic moments of Mn2+ions for the constructed spin orbitals are perpendicular to the layers. The magnetic moments of Mn2+ions in the nearest layers are antiferromagnetically ordered via the Anderson mechanism.
Spin Diffusion and Oscillations of the Magnetization at High-Frequency Spin Injection
Authors: Bebenin N. G.
Published: April 2024

The frequency dependence of the nonequilibrium magnetization arising in an electron gas due to spin injection from a half-metallic ferromagnet into a nonmagnetic material is theoretically analyzed. It is shown that high-frequency spin injection gives rise to nonequilibrium magnetization waves, which decay at a length much smaller than the spin diffusion length. This reduces the efficiency of spin injection.
PT-Symmetric Microwave Photoconductivity in Heterostructures Based on the xCdxTe Topological Phase
Authors: Chmyr' S. N. , Kazakov A. S. , Galeeva A. V. , Dolzhenko D. E. , Artamkin A. I. , Ikonnikov A. V. , Mikhaylov N. N. , Dvoretskiy S. A. , Bannikov M. I.
Published: April 2024

ThePT-symmetric photoconductivity has been detected for the first time in microwave-irradiated heterostructures based on thick Hg1 −xCdxTe films with the CdTe contentxcorresponding to the topological phase although the magnetic field symmetry (Tsymmetry) and the symmetry in the positions of potential contact pairs (Psymmetry) are not conserved separately. The microwave photoconductivity in similar heterostructures based on the trivial Hg1 −xCdxTe phase is bothP- andT-symmetric.
Temperature Studies of Raman Spectra in MnBi2Te4 and MnSb2Te4 Magnetic Topological Insulators
Authors: Maksimov A. A. , Tartakovskiy I. I. , Aliev Z. S. , Amiraslanov I. R. , Abdullaev N. A. , Zverev V. N. , Dzhakhangirli Z. A. , Sklyadneva I. Yu. , Otrokov M. M.
Published: April 2024

Raman spectra of magnetic topological crystalline insulators in a wide temperature range including the magnetic ordering region are studied in detail. The anharmonicity parameters and Grüneisen mode parameters of Raman-active phonons in the studied crystals have been determined. It has been shown that the temperature dependence of the frequency of theA1g(1)(~48 cm–1) phonon in MnBi2Te4coincides within ±0.1 cm–1with the standard anharmonic model disregarding the spin–phonon coupling. The polarization dependences of Raman spectra in the MnSb2Te4crystals indicate that Sb and Mn atoms are strongly mixed in them unlike the isostructural MnBi2Te4crystals.
Tunneling Mechanism for Changing the Motion Direction of a Pulsating Ratchet. Temperature Effect
Authors: Rozenbaum V. M. , Shapochkina I. V. , Trakhtenberg L. I.
Published: April 2024

A pulsating ratchet with a spatially periodic double-well potential profile undergoing shift fluctuations for half a period is considered. The motion direction in such a ratchet is determined by the probability of overcoming which of the barriers surrounding the shallow potential well is greater. At relatively high temperatures, in accordance with the Arrhenius law, the probabilities of overcoming the barriers are determined by their heights, and at temperatures close to absolute zero, when the ratchet moves according to the tunnel mechanism, the barrier shapes are also important. Therefore, for narrow high and low wide barriers, the overcoming mechanism may turn out to be different and, moreover, dependent on temperature. As a result, a temperature-induced change in the direction of the ratchet motion is possible. A simple interpolation theory is presented to illustrate this effect. Simple criteria are formulated for the shape of the potential relief, using which one can experimentally observe motion reversal.
Terahertz Third-Harmonic Generation in Topological Insulators Based on Bismuth and Antimony Chalcogenides
Authors: Kuznetsov K. A. , Kuznetsov P. I. , Frolov A. D. , Konovalov A. M. , Kovaleva P. M. , Kitaeva G. Kh.
Published: April 2024

Terahertz third-harmonic generation in topological insulators based on bismuth and antimony chalcogenides has been experimentally investigated. It has been found that the third-harmonic conversion efficiency is inversely proportional to the electron Fermi energy; among the materials under study, antimony telluride has the highest conversion efficiency.
New Soliton Regime of Generation of Broadband Terahertz Radiation by Laser Pulses with Tilted Wave Fronts
Authors: Sazonov S. V. , Ustinov N. V.
Published: April 2024

A new soliton-like regime of generation of terahertz radiation by optical pulses with tilted wave fronts is analyzed. It has been shown that the diffraction of an optical pulse is of fundamental importance for the formation of optical–terahertz soliton. A nonsoliton broadband terahertz component is generated synchronously with the soliton component of radiation. Two matching conditions called “super-Cherenkov” and “anti-Cherenkov” have been revealed under which generation is the most efficient. In the former and latter cases, the optical terahertz soliton propagates ahead and behind the nonsoliton terahertz component, respectively.
Two Dynamical Regimes of Coherent Columnar Vortices in a Rotating Fluid
Authors: Tumachev D. D. , Filatov S. V. , Vergeles S. S. , Levchenko A. A.
Published: April 2024

Vortex flow generation in an incompressible fluid was investigated experimentally inside a rotating closed cubic aquarium. The flow was excited by producing small-scale eddies near the side edges of the cube. Coherent columnar vortices-cyclones extending from the bottom to the lid of the cube were observed in the liquid volume. The lifetime of the cyclones was much longer than the attenuation time due to the viscous friction on the bottom and the lid. It was found that there are two regimes of quasi-two-dimensional turbulence, which are characterized by different ways of interaction between quasi two-dimensional flow and inertial waves. The radial profiles of the time- averaged azimuth velocity in the coherent vortices in these two regimes are investigated. It is shown that the vortices differ in size and in vorticity distribution along the radius.
Coulomb Correlation Gap at Magnetic Tunneling between Graphene Layers
Authors: Khanin Yu. N. , Vdovin E. E. , Morozov S. V. , Novoselov K. S.
Published: April 2024

The strong suppression of equilibrium magnetic tunneling in a graphene/hBN/graphene heterostructure caused by the Coulomb correlation gap in the tunneling density of states has been found. Comparison has shown that the suppression of the equilibrium tunneling conductivityG0in a high magnetic field with a decrease in the temperature and the dependence of the observed gap width Δ on the filling factor of Landau levels ν are qualitatively similar to the respective results of similar experiments in GaAs heterostructures and has confirmed our hypothesis concerning the nature of the effect. However, the determined gap width Δ is much larger than those measured in all previous works in semiconductor heterostructures probably because the cyclotron energy in graphene is much higher than that in GaAs in the region of low Landau levels.
Nonreciprocity of the Flexomagnetoelectric Effect with Respect to the Sign of Affecting Charges
Authors: Magadeev E. B. , Vakhitov R. M.
Published: April 2024

The ferromagnetic film in the electric film of a charged filament is studied theoretically. It has been shown that solitary magnetic inhomogeneities can be formed in this film in the presence of the inhomogeneous magnetoelectric interaction; their structure and nucleation conditions are determined by the sign of interacting charges. In particular, it has been established that the minimum magnitude of the linear charge density for the formation of an inhomogeneity in a positively charged filament is several times different from that for a negatively charged filament.
Goldstone Mode of Skyrmion Crystal
Authors: Timofeev V. E. , Aristov D. N.
Published: April 2024

We discuss the Goldstone mode of skyrmion crystal in a model of two-dimensional ferromagnet with the Dzyaloshinskii–Moriya interaction in magnetic field. We use stereographic projection approach to construct skyrmion crystal and consider skyrmion displacement field. The small overlap of the individual skyrmion images restricts the potential energy to the interaction of nearest neighboring displacements. The closed form of the Goldstone mode dispersion is found and its dependence on the magnetic field is studied. We use semiclassical quantization to define the Green’s function and show that the propagation of displacements through the crystal changes its tensorial form from anisotropic to isotropic one at large times.
Giant Planar Hall Effect in an Ultra-Pure Mercury Selenide Single Crystal Sample
Authors: Bobin S. B. , Lonchakov A. T.
Published: April 2024

A giant planar Hall effect with an amplitude of about 50 mΩ cm at a temperature ofT= 80 K in a magnetic field of 10 T has been detected in an ultra-pure HgSe single crystal sample with an electron density of 5.5×1015cm–3. Its oscillating dependence on the rotation angle of the sample in various magnetic fields has been determined. Attributes (oscillation period, positions of extrema, correlation between the amplitudes of planar Hall and planar longitudinal magnetoresistance) indicate that the planar Hall effect in this nonmagnetic gapless semimetal with an isotropic Fermi surface originates from the chiral anomaly. This is a solid argument for the topological nature of the electronic spectrum of HgSe.
Features of the Scaling of the Anomalous Hall Effect in (CoFeB)x(LiNbO3)100 − x Nanocomposite Films Below the Percolation Threshold: Manifestation of the Cotunneling Hall Conductance?
Authors: Nikolaev S. N. , Chernoglazov K. Yu. , Bugaev A. Sh. , Granovskiy A. B. , Ryl'kov V. V.
Published: April 2024

A scaling behavior of the anomalous Hall effect resistivity ρAHEversus the longitudinal resistivity ρ in (CoFeB)x(LiNbO3)100 −xnanocomposites with a low content of dispersed Co and Fe atoms (Nd~ 4 × 1020cm−3) in an amorphous LiNbO3matrix is studied in the rangex≈ 40–48 at % below the percolation thresholdxp≈ 49 at %. A logarithmic temperature dependence of the conductivity σ ~ lnT  has been observed in the rangex≈ 44–48 at %, which is transformed in the rangex≈ 40–42 at % to a square root law lnσ ∝ ‒(T0/T)1/2, which is characteristic of cotunneling transport processes in nanocomposites. It has been found that the exponentn≈ 0.24 in the scaling law ρAHE/x∝ [ρ(x)]ncoincides within an accuracy of 5% with the exponentnin a similar dependence for nanocomposites based on the (CoFeB)x(Al2O3)100 −xmatrix with a high contentNd~1021–1022cm–3and with the exponentnin a parametric dependence ρAHE∝ [ρ(T)]nfor the samples with the minimum contentx≈ 40 at %. The found features are attributed to the correlated change in the probability of cotunneling transitions in a set of more than three centers under the effect of spin–orbit coupling. The manifestation of the barrier tunneling anomalous Hall effect at granule interfaces is also p-ossible.