Editors’ choice

The Editorial Board of the journal “Bulletin of the Russian Academy of Sciences: Physics” monthly assigns one of the articles of each thematic issue the honorary status of “Editor’s Choice”. We hope that the selected articles will be of interest to a wide range of readers.


Volume 86, issue 1, January 2022

Thematic issue “Wave Phenomena: Physics and Applications”

A. I. Korolkov, K. S. Kniazeva, A. S. Shurup, Acoustic location based on triple correlation // Bulletin of the Russian Academy of Sciences: Physics, 2022, Volume 86, Issue 1, P. 70-73.

Acoustic location of the environment is widely used in various fields of human activity, and for some representatives of the natural word it is completely indispensable. For example, bats use acoustic waves to move safely in conditions of poor visibility, to detect various distant objects. The simplest in terms of engineering implementation is the echolocation method, in which the environment is sounded with pulses of a special form, after which the signal, reflected from a stationary or moving obstacle, is recorded by the receiving system. The standard (double) correlation between the emitted and received signals makes it possible to identify the presence of an obstruction, as well as to estimate different characteristics of the object off which the signal was reflected, for example, the distance to it, or its speed. In this paper, we have demonstrated the possibility of using triple correlation in problems of acoustic location, which can improve the noise immunity of estimates, for example, in the case of multipath signal propagation, which is useful in the presence of cloaking scatterers, as well as in problems of estimating the trajectory of a moving scatterer.

The usage of triple correlation, or its frequency counterpart “bispectrum”, has long been proven in the analysis of signals in optics, cosmology, and oceanology. However, this approach has not been widely used in acoustic location problems. One of the reasons is related to the fact that for these purposes it was necessary to develop a special signal, the triple autocorrelation function of which is close to delta function. As a possible solution to this problem, in this work it is proposed to use a random sequence of numbers corresponding in the complex representation to the values of the cube root of unity. The triple correlation function of such a signal is close to the delta function, as it is desired. The existing positive experience of using triple correlation in various fields of physics, together with the results of numerical and laboratory experiments presented in this work, opens the broad prospects of the considered approach in acoustic location problems.

The work was carried out by the staff and graduate students of Acoustics Department, Faculty of Physics, Moscow State University, P. P. Shirshov Institute of Oceanology, RAS, The Schmidt Institute of Physics of the Earth, RAS, working in the field of acoustics of natural environments in the direction of the development of multidimensional methods for processing signals and fields.


Volume 85, issue 12, December 2021

Thematic issue “Nanooptics photonics and coherent spectroscopy”

E. P. Kozhina, A. I. Arzhanov, K. R. Karimullin, S. A. Bedin, S. N. Andreev, A. V. Naumov, Using Epi-Luminescence Microscopy to Visualize and Control the Distribution of Luminophores on a Highly Developed Surface // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 12, P. 1393–1399.

The synthesis and research of new metamaterials is an interesting task in science and technology. Different topologies of surfaces, their structural features, optical and spectral properties make such materials unique in their class. Among such materials, metasurfaces for SERS spectroscopy, which are widely used in medicine and supersensitive sensors, are especially distinguished. Today there are various methods of synthesis of SERS active metasurfaces: from simple colloidal solutions to nanostructures with controlled geometry. Among them there is the method of template synthesis based on polymer track etched membranes. It makes it possible to produce metasurfaces with controlled geometry nanowires as well as dendritic nanostructures. Since the surface of such metasurfaces is highly developed and hydrophilic, the applied substance on such surfaces can spread over a large area. This becomes a problem when assessing the enhancement factor of such metasurfaces, when one needs to know from what amount of analyte under study the SERS spectra are obtained.

The work examined SERS active substrates with dendritic nanostructures fabricated by the template synthesis method. By varying the parameters of the synthesis, the surfaces with dendritic nanostructures of different sizes were produced. This changed the wettability parameters of such substrates. To evaluate these properties, depending on the synthesis parameters, an optical (luminescent) diagnostic method was used. The essence of the method is to observe luminescent images of samples as a solution of semiconductor quantum dots (a solution of CdSe/CdS/ZnS QDs in toluene) spreads over the substrate surface. After drying of the solvent, when the substrate with luminescent quantum dots is illuminated with the appropriate laser radiation, it is possible to observe the spreading area in the scheme of a confocal epi-luminescent microscope, estimate the wetting area, and study the structural features of the surface of the samples under study.

The study was carried out by a team that is part of the Inter-Institute Scientific Group on Laser Selective Spectroscopy and Nanoscopy. Works on the template electrochemical synthesis of nanostructured metasurfaces and the study of their optical properties are carried out at the Moscow State Pedagogical University in cooperation with the Federal Research Center “Crystallography and Photonics” of the Russian Academy of Sciences. Numerical simulation of local fields near nanostructures was carried out in cooperation with the Moscow Polytechnic University. Experimental studies of metasurfaces by luminescence microscopy were carried out in the Laboratory of Electronic Spectra of Molecules of the Institute of Spectroscopy of the Russian Academy of Sciences. The technique of SERS-spectroscopy and sensorics is being developed within the framework of the state task of the Lebedev Physical Institute RAS at the Troitsk Branch of LPI.

Volume 85, issue 11, November 2021

Thematic issue “Physics of Cosmic Rays”

N. S. Khaerdinov, D. D. Dzhappuev, K. Kh. Kanonidi, A. U. Kudzhaev, A. N. Kurenya, A. S. Lidvansky, V. B. Petkov & M. N. Khaerdinov, Disturbance of a Glow in the Night Sky in Clear Weather at Middle Latitudes // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 11, P. 1317–1319.

An experiment studying the variations of cosmic rays during thunderstorms at the Baksan Neutrino Observatory (BNO) two decades ago has resulted in discoveries of some processes important for understanding the dynamics of thunderstorms and the role of cosmic rays in it. At the present time new data channels are added to the original observations of variations of the soft (electrons, positrons, and gamma rays) and hard (muons) components of secondary cosmic rays and their correlations with near-ground electric field. Now the magnetic and seismic data are analyzed, and remote video cameras observe the sky above the BNO from distances of 1 km and 75 km during night-time thunderstorms. A method of estimating the stratosphere electric field has beendeveloped, based on the analysis of disturbances of muon flux on the ground level (The Carpet air shower array at an altitude of 1700 m a.s.l.). Joint analysis of all these data allowed us to discover some peculiar phenomena in ordinary thunderstorms, including high-altitude discharges of a new type that produce glow in the upper atmosphere. The unique property of the event described in the present paper is the complete absence of usual thunderstorm activity: one can see stars on video frames (there are no thunderclouds), and the surface electric field meter indicates near-background values (fair weather field). Nevertheless, the electric field in the troposphere over the mountains, reconstructed from muon intensity data, is quite considerable, and large-scale glow is observed, invisible by eye but recorded by video cameras (panel a in Figure shows brightness of sky glow in arbitrary units). Some seismic activity preceded the glow (data of the inclinometer in panel e in Figure, where 1 V corresponds to 5 arc seconds), and the entire event occurred on the background of a magnetic storm on August 31, 2019 (magnetic indices SYM-D and SYM-H in panels b and c). Also, a significant local disturbance of the delay of GPS accurate time radio signal was detected for the first time (panel d). This disturbance corresponds to three-time increase of the total electron content (TEC) of the ionosphere, and it began immediately after a fast disturbance of the muon intensity (corresponding potential difference deduced from muon variations is shown in panel f). An interpretation of this unusual event is suggested in the paper, according to which the underground horizontal pulsed electrical discharge took place. The fact of detection of a series of successive geophysical disturbances finally resulting in compensation of the atmospheric current generated by vibration of the Earth’s crust in the region of potentially active volcano (Elbrus) by interhemispheric current indicates to a mechanism of energy-exchange interaction between two systems, the solar wind and the inner structures of the Earth.

The team of authors includes the staff members of the Institute for Nuclear Research of the Russian Academy of Sciences (RAS) and of the Baksan Neutrino Observatory of this Institute, and a collaborator from the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of RAS. The data of high-precision inclinometers of Laboratory No. 1 of the North Caucasus Geophysical Observatory of Shmidt Institute of Physics of the Earth of RAS were used.


Thematic issue “Electromagnetic Field and Materials (Fundamental Physical Researches)”

A. B. Khutieva, A. V. Sadovnikov, A. Yu. Annenkov, S. V. Gerus & E. H. Lock, Diffraction of the Superdirectional Beam of a Surface Spin Wave on a Low-Contrast Magnon Crystal // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 11, P. 1205–1208.

As is known, a magnon crystal (MC) is an artificially created periodic structure in a magnetically ordered medium. If the energy of a periodic perturbation of the medium is small compared to the total magnetic energy of the medium, then such an MC is usually called low-contrast MC. For example, such a crystal appears if a ferrite film is magnetized by an external uniform magnetic field, to which a small stationary spatially periodic magnetic field is added.

If a superdirected beam (which has no diffraction divergence) of a surface spin wave (SSW) is directed at a low-contrast MC, then as a result of its diffraction through the MC, the initial beam splits into narrow diffractive beams, so-called doublers of zero and first order beams diffraction. Since the beam incident on the MC is superdirectional, then all the appearing doubler beams also have this property (despite the fact that they are much narrower than the original beam) and are characterized by low diffraction divergence: as can be seen from the figure, they practically do not spread over propagation in both experimental and calculated diffraction patterns. In addition, as can be seen from the figure, the interaction of the SSW beam with the MC is accompanied by a displacement of the initial beam and a significant broadening of the film region, in which the doubler beams of the zero and first diffraction orders are located. Note that the calculations that were also performed for the MC region show how the SSW beam diffracts inside the MC.

Experimental visualized patterns describing the diffraction of SSW through MC were obtained by microwave probing on a unique experimental setup developed by the authors of the article. In contrast to setups that use Brillouin light scattering to obtain SSW diffraction patterns, the created setup makes it possible to obtain such patterns on a surface with area of ~ 40 cm2. The setup includes a measurer of complex transmission coefficient, a computer, a permanent magnet, and movable transducer probes, which can be used to excite spin wave beams with various parameters in the structure under study, receive these beams and measure their characteristics. Thus, the setup makes it possible to study the distribution of the amplitude and phase of spin waves in the plane of various ferrite structures. Numerical calculations corresponding to the experimental diffraction patterns (see figure below) were carried out using micromagnetic modeling based on the MUMAX3 software package by the finite difference method based on the Landau-Lifshitz equation with a dissipative term in the form proposed by Hilbert. Experimental (a) and calculated (b) diffraction patterns in the plane of the structure, describing the distribution of the amplitude of the SSW with a frequency of 3056 MHz during its propagation through a low-contrast MC are shown in Figure, where 1 – is SSW-exciting linear transducer 5 mm long, 2 and 3 – are nominal boundaries of the superdirectional SSW beam when there is no MC, 4, and 5 – are MC boundaries.

The team of authors includes leading specialists in the study of spin waves from the Saratov State University (SSU) and Kotelnikov Institute of Radio Engineering and Electronics (Fryazino Branch) of Russian Academy of Sciences, who performed, respectively, numerical calculations and experiments in this work. Mention must be made, that one of the authors of the work is a 4th year student from SSU.

Volume 85, issue 10, October 2021

Thematic issue “Nuclear Physics and Elementary Particle Physics. Nuclear Physics Technologies”

A. A. Bogachev, E. M. Kozulin, G. N. Knyazheva, I. M. Itkis, K. V. Novikov, T. Banerjee, M. Cheralu, M. G. Itkis, E. Mukhamedzhanov, D. Kumar, A. Pan, I. V. Pchelintsev, I. V. Vorob’ev, W. H. Trzaska, E. Vardaci, A. di Nitto, S. V. Khlebnikov, I. Harka, and A. Andreyev, Study of Binary Processes in the Reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn Leading to the Formation of Neutron-Deficient Compound 180, 190Hg Nuclei // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 10, P. 1080–1084.

Nowaday the fission process of pre-actinide nuclei is of great scientific interest. It is well-known that these nuclei fission mainly symmetrically even at low excitation energies. However, in recent investigations of fission properties of neutron-deficient isotope 180Hg at the excitation energy of about 10 MeV, asymmetric mass distribution of fission fragments was observed. It is contradictory to the expected symmetric one, influenced by neutron shell N=50. This discrepancy caused intensive studies of the fission process of nuclei from this region.

Detailed investigations of fission of the compound nuclei 180, 190Hg, formed in the reactions 36Ar+144, 154Sm, showed that the mass distributions of the fragments are the superpositions of the symmetric and asymmetric modes. The most probable mass numbers of the light and heavy fragments for asymmetric mode are 80/100 and 83/107 a.m.u. for 180Hg and 190Hg, respectively. Supposing unchanged charge density approach, the masses of light and heavy fragments correspond to the same proton numbers Z1/Z2=35/45 for both compound nuclei, whereas the neutron numbers change according to the compound nucleus mass numbers. Due to this one can suppose that the properties of the asymmetric fission are mainly determined by the proton configurations. With increasing excitation energy of the fissioning nucleus the growth of the symmetric mode associated with the liquid-drop component is observed, whereas the contribution of the asymmetric part decreases.

The reaction 68Zn+112Sn leads to the formation of the same 180Hg nucleus, as in the reaction 36Ar+144Sm. But experimentally measured mass-energy distributions of the reaction products drastically change, despite that the excitation energies of the compound systems are very close to each other: 48 and 53 MeV, respectively (see the Figure). This discrepancy in the reaction fragments distributions connected with the quasifission process in more symmetric system 68Zn+112Sn. This is also interesting and surprising observation, because the quasifission process seemed to be insignificant in the interactions of such not so heavy nuclei.

The experiments were carried out with use of the double-arm time-of-flight spectrometer CORSET at the U-400 cyclotron in Flerov Laboratory of Nuclear Reactions of Joint Institute for Nuclear Research and at the K-130 cyclotron of the Accelerator Laboratory of Physics Department of the University of Jyväskylä (Finland). This work was supported by the Russian Foundation for Basic Research (project no. 19-52-45023).

Volume 85, issue 9, September 2021

Thematic issue “Phase Transition & New Materials”

Yu. M. Gufan, E. N. Klimova, and R. A. Kutuev, Symmetry of the Non-Atomic Interactions of N-Atomic Energy and the Atomistic Theory of High-Order Elastic Modules // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 9, P. 998-1002.

Titanium trisulfide (TiS3) – one of the representatives of trichalcogenides, a material with great potential for field-effect transistors, photodetectors, and power generators. Studies of TiS3 single crystals in different scientific groups have shown that their resistivity at room temperature can differ by more than 10 times. It was assumed that an increase in the conductivity of TiS3 crystals can be associated with a violation of the stoichiometry of the composition, in connection with which it can be assumed that the conductivity depends on the density of sulfur vacancies.

The method of high-resolution transmission scanning electron microscopy with registration of electrons scattered at high angles (10-15°, in comparison with Bragg scattering, in which electrons are scattered at angles of 3-5°) using a high-angle ring dark-field detector allows one to obtain contrast from columns of atoms depending on the atomic number Z to the power γ (γ = 1.6-2) and on the number of atoms in a chain parallel to the e-beam. Using such images, it is possible to assume the presence of vacancies, try to estimate their number in the column and to determine the density of vacancies in the sample.

In this work, we simulated the images of TiS3 single crystals with different numbers of sulfur vacancies in chains parallel to the e-beam for different sample thicknesses. An easy and fast method was proposed for estimating the number of vacancies in a chain from the intensity of images of atomic columns. The results showed that the used method differs insignificantly from the known method for estimating the number of atoms by approximation by Gaussians, and the scatter of data can be associated with the position of vacancies in the chain of sulfur atoms parallel to the electron beam. The calculations made it possible to estimate the density of vacancies in low-resistance and high-resistance samples and to confirm the hypothesis about the influence of vacancies of sulfur atoms on the conductivity. In addition, the ordering of vacancies in low-resistance TiS3 samples was found.

The team of authors includes leading specialists of the Federal Research Center “Crystallography and Photonics of the Russian Academy of Sciences”, National Research Center “Kurchatov Institute”, Kotelnikov Institute of Radio Engineering and Electronics Russian Academy of Sciences working in the field of condensed matter physics and structural methods in materials science. The theory of using a unique method for evaluating the vacancy structure in crystals has been implemented in the laboratory of electron microscopy of the Federal Research Center “Crystallography and Photonics of the Russian Academy of Sciences”.


Thematic issue “Structure and Dynamics of Molecular Systems”

O. A. Raitman, E. V. Raitman, N. L. Zaichenko, G. V. Lyubimova, A. A. Scherbina, and A. V. Lyubimov, Controlling the Aggregation of Amphiphilic Spiropyrans in Langmuir Monolayers // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 8, P. 868-872

The ability to calculate simple mechanical characteristics of a crystal is an extremely important property for any theory of the structure of a solid. The presence of such a possibility – provided the consistency of the result obtained – first means some general consistency of the theory: the area of its fundamental applicability in this case can be quite wide, not limited, for example, to the microscopic structure of the crystal, which means that the theory can surpass the status of a highly specialized model. In addition, the ability to calculate the mechanical characteristics of an object can be used to obtain constraints on the values of the parameters appearing in these calculations. The fact is that the mechanical characteristics, although often with rather moderate accuracy, are amenable to direct measurement on samples. If the same characteristics can be expressed – if not analytically, then at least computationally – through the parameters of the theory, then from these expressions ranges of parameter values can be obtained that agree with the measurement results, or at least do not contradict them.

It is shown that the requirement of computability of high-order elastic moduli for an abstract crystal itself leads to rather significant restrictions on how a microscopic theory of its structure, based on modeling the interaction of particles constituting the crystal, can look like. Based on this requirement, the authors construct a criticism of the now widely used approaches to the construction of a theory (the pseudopotential method, calculations from first principles, the electron density functional method, the embedded atom method) and offer a schematic description of how a theory could be constructed based on the model direct accounting for multiparticle interactions. In this paper the restrictions of the theory are obtained on the dependence of the calculated total potential energy of interaction of the particles constituting the crystal on the polynomials determined from symmetric considerations in the radius vectors of the particles constituting bounded and determined by symmetry clusters. Since the result is based only on considerations determined by the symmetry of the crystal structure, the requirements obtained (more precisely, the general scheme for their preparation) can be considered mandatory for the microscopic theory, which claims to be able to describe the mechanical properties of a crystal.

Volume 85, issue 8, August 2021

Thematic issue “Electron and probe microscopy, and complementary methods in research of nanostructures and nanomaterials”

V. I. Bondarenko, I. N. Trunkin, I. G. Gorlova, N. B. Bolotina, and A. L. Vasiliev, Investigating the Vacancy Structure of TiS3 Single Crystals // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 8, P. 858-862

Titanium trisulfide (TiS3) – one of the representatives of trichalcogenides, a material with great potential for field-effect transistors, photodetectors, and power generators. Studies of TiS3 single crystals in different scientific groups have shown that their resistivity at room temperature can differ by more than 10 times. It was assumed that an increase in the conductivity of TiS3 crystals can be associated with a violation of the stoichiometry of the composition, in connection with which it can be assumed that the conductivity depends on the density of sulfur vacancies.

The method of high-resolution transmission scanning electron microscopy with registration of electrons scattered at high angles (10-15°, in comparison with Bragg scattering, in which electrons are scattered at angles of 3-5°) using a high-angle ring dark-field detector allows one to obtain contrast from columns of atoms depending on the atomic number Z to the power γ (γ = 1.6-2) and on the number of atoms in a chain parallel to the e-beam. Using such images, it is possible to assume the presence of vacancies, try to estimate their number in the column and to determine the density of vacancies in the sample.

In this work, we simulated the images of TiS3 single crystals with different numbers of sulfur vacancies in chains parallel to the e-beam for different sample thicknesses. An easy and fast method was proposed for estimating the number of vacancies in a chain from the intensity of images of atomic columns. The results showed that the used method differs insignificantly from the known method for estimating the number of atoms by approximation by Gaussians, and the scatter of data can be associated with the position of vacancies in the chain of sulfur atoms parallel to the electron beam. The calculations made it possible to estimate the density of vacancies in low-resistance and high-resistance samples and to confirm the hypothesis about the influence of vacancies of sulfur atoms on the conductivity. In addition, the ordering of vacancies in low-resistance TiS3 samples was found.

The team of authors includes leading specialists of the Federal Research Center “Crystallography and Photonics of the Russian Academy of Sciences”, National Research Center “Kurchatov Institute”, Kotelnikov Institute of Radio Engineering and Electronics Russian Academy of Sciences working in the field of condensed matter physics and structural methods in materials science. The theory of using a unique method for evaluating the vacancy structure in crystals has been implemented in the laboratory of electron microscopy of the Federal Research Center “Crystallography and Photonics of the Russian Academy of Sciences”.


Thematic issue “Structure and Dynamics of Molecular Systems”

O. A. Raitman, E. V. Raitman, N. L. Zaichenko, G. V. Lyubimova, A. A. Scherbina, and A. V. Lyubimov, Controlling the Aggregation of Amphiphilic Spiropyrans in Langmuir Monolayers // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 8, P. 868-872

The possibility of controlling the physicochemical properties of photosensitive materials using external influences opens broad prospects for their application in various fields of science and technology. Thus, the phenomenon of changes in the optical characteristics of ultrathin films based on photochromic compounds because of aggregation rearrangements can be used in the development of information recording devices and optical signal processing, in holography, medicine, sensorics, etc. It is known that a several spiro compounds exhibit thermally and photoinduced H– and J-aggregation in organic solvents; however, the behavior of Langmuir monolayers from amphiphilic spiropyrans, which are resistant to temperature changes, a high activation barrier of the isomerization reaction, and significant spectral distinguishability of isomers, is practically not studied. This paper devoted to studying the possibility of controlling the aggregation state of Langmuir monolayers of photochromes on liquid substrates by introducing a diluent and varying the surface pressure is of increased interest for scientists working in the field of photochemistry, as well as physical, colloidal, and supramolecular chemistry. It is shown that amphiphilic 1′-hexadecyl-3 ‘, 3′-dimethyl-6-nitro-1′, 3′-dihydrospiro [chromene-2,2’-indole] (SP1) in the spiro form does not form stable monolayers on the aqueous subphase, while the merocyanine form of this compound completely spreads over the surface and forms a true monolayer. It was demonstrated that in the planar state of the studied substance the tendency to aggregation sharply increases, which is confirmed by the appearance and growth of the absorption band in the 620 nm region. The formation of mixed monolayers of SP1 and cetyl alcohol molecules, as well as external mechanical action, makes it possible to control the degree of aggregation of spiropyran in monomolecular films and achieve complete spreading of the compound over the water surface while maintaining the photochromic properties of the substance in the two-dimensional state. The results obtained open broad prospects for the use of compounds of the spiropyran series in molecular electronics and for the creation of nanoscale optically active systems.

The team of authors includes leading specialists from the Mendeleev University of Chemical Technology, Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences and the Semenov Federal Research Center of Chemical Physics of the Russian Academy of Sciences. The employees of the last one work in the field of synthesis of optically active and photosensitive compounds, are engaged in their incorporation into polymer matrices. Scientific group from the Mendeleev Chemical Technical University and Frumkin Institute of Physical Chemistry and Electrochemistry RAS is studying the behavior of chromo-, ion- and luminophores at the interface. The cooperation of these scientific groups makes it possible to carry out unique research aimed at studying the laws governing the course of photochemical reactions in two-dimensional ordered systems.

Volume 85, issue 7, July 2021

Thematic issue “Phase Transformations and the Strength of Crystals”

R. V. Sundeev, A. M. Glezer, A. V. Shalimova, A. V. Krivoruchko, A. A. Veligzhanin, O. V. Vakhrushev, EXAFS and EELFS Spectroscopy in Analyzing the Atomic Structure of the Bulk and Surface Ti50Ni25Cu25 Alloy Domains upon Extreme Impacts by Megaplastic Deformations and Quenching from a Melt // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 7, P. 732-739

Under extreme exposure, i.e. large (megaplastic) deformations (MPD), the transformation of the atomic structure in the crystalline state of materials is realized under conditions of nonequilibrium thermodynamics and the specificity of relaxation processes (especially at low temperatures). This leads to the appearance of unusual structural states with special characteristics of chemical and topological inhomogeneity. It is most difficult to obtain the structural features under the influence of MPD in amorphous alloys, where local inhomogeneities of the atomic structure can arise. Under these conditions, the combined application of the EXAFS and EELFS methods is extremely necessary and effective, allowing one to represent the evolution of transformations of the atomic system both in the bulk and on the surface of the alloys as the MPD value varies.

There is a unique Ti50Ni25Cu25 alloy among functional alloys with shape memory effect which can be obtained in the amorphous state using two different methods of extreme exposure: quenching from the liquid state (QLS) and MPD. We present the results of a detailed structural analysis of this unique material after QLS and MPD. The studies of the local atomic structure of the initial amorphous state obtained by the QLS method and the secondary amorphous state obtained by the MPD were performed using the EXAFS spectroscopy method under synchrotron radiation (shown in the figure) and the EELFS spectroscopy method. Comparison of changes in the local atomic structure of the crystalline Ti50Ni25Cu25 alloy during MPD on the surface of the sample and in the bulk of the sample showed that the volume of the material is gradually amorphous of the crystalline Ti50Ni25Cu25 alloy under study. The local atomic structure of this alloy after MPD (n = 6) reproduces the local atomic structure of the alloy after MPD. In this case, on the surface, the studied alloy after MPD remains, most likely, in a state close to the crystalline state and is noticeably supersaturated with oxygen atoms.

The team of authors includes leading specialists of the Bardin Central Research Institute of Iron and Steel Industry, National Research Center “Kurchatov Institute”, MIREA – Russian Technological University and National Research Technological University “MISiS”, working in the field of physics of large plastic deformations and structural methods for studying amorphous and nanocrystalline materials. The theory and practice of EELFS technique was developed and implemented in the laboratory of surface physics of the Kurdyumov Institute of Metal Science and Physics of Metals, as a part of the Bardin Central Research Institute of Iron and Steel Industry.

Volume 85, issue 6, June 2021

Thematic issue “Acoustic Physics”

A. V. Sadovnikov, S. A. Nikitov, Using Mandelstam–Brillouin Spectroscopy to Study Energy-Efficient Devices for Processing Information Signals on the Basis of Magnon Straintronics // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 6, P. 595-598

We show how an approach based on the methods of magnon straintronics can be used to create magnon logic devices with control over the amplitude and phase of spin waves. Spin wave quanta – magnons propagating in magnetic materials, due to their unique properties, can be used in promising systems for processing information signals with low energy consumption at different spatial and time-domain scales. Low power consumption is ensured by the fact that magnons are chargeless quasiparticles and during their propagation in the layers of magnetic dielectrics there is practically no Joule heating.

Recently, there has been increasing interest in research on energy efficient methods for controlling the properties of propagating spin waves. Magnon devices are considered as an alternative to modules that carry out logical operations based on elements of semiconductor microelectronics based on the use of the charge of current carriers (electrons or holes). In this case, the presence of the spin of current carriers and spin-wave excitations makes it possible to create the next generation of electronics devices – dielectric magnons with significantly improved parameters of speed, power consumption, and smaller spatial dimensions of elements. As a demonstration of this physical effect, using the method of Mandelstam-Brillouin spectroscopy, in structured ferrite-piezoelectric bilayers, voltage-controlled spin-wave transport along a lateral structure consisting of two magnon-crystal microwave guides was investigated. The possibility of efficient tuning of the spin-wave characteristics by applying an electric field to the piezoelectric layer is shown. The transformation mechanism of the spectra of spin-wave signals consists in the value of the gradient of the internal magnetic field controlled by elastic deformations in the region near the gap between the lateral structures. The results obtained can be used to create energy-efficient devices for processing information signals, such as demultiplexers with frequency-space selectivity.

The authors are from Saratov State University and the Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, carrying out research in the Laboratory of magnon metamaterials, created in Saratov in 2012. Two unique complexes of Mandelstam-Brillouin spectroscopy of magnetic materials and living systems, the only two in the Russian Federation, have been launched in the laboratory and are in continuous operation.

Volume 85, issue 5, May 2021

Thematic issue “Nuclear Physics and Elementary Particle Physics. Nuclear Physics Technologies”

M. V. Chushnyakova, I. I. Gontchar, N. A. Khmyrova, A. А. Klimochkina, Relativistic Mean-Field Effective Nucleon–Nucleon Forces in the Dynamic Modeling of Heavy Ion Fusion // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 5, P. 490-495

The work is devoted to one of the most interesting problems of modern nuclear physics – dynamic modeling of the fusion of atomic nuclei. Experiments on the collision of complex nuclei have been carried out in many laboratories in different countries since the 1960s. As a result of these experiments, a new class of nuclear reactions was discovered – deeply inelastic transfer reactions, and nuclei of new chemical elements with atomic numbers from 104 to 118 were synthesized. Computer simulation of collisions leading to nuclear fusion helps to understand the features of the process and reduce the cost of experiments.

One of the important components in our calculations is the interaction energy of two nuclei, which we obtain by convolving the nucleon-nucleon interaction (“NN forces”) with the densities of interacting nuclei. In recent years, the forces obtained in the framework of the theory of the relativistic mean field (TRMF forces) are considered as the most progressive NN forces. We have systematically applied these forces to simulate nuclear fusion in this paper and also in [1. M.V. Chushnyakova et al. // Journal of Physics G. 48 (2021) 015101]. In total, 6 sets of parameters of TRMF forces that were found in the literature were analyzed. Unexpectedly, it turned out that many of these parameters lead to an unrealistic energy of the nucleus-nucleus interaction: it lacks a region where the strong nuclear interaction exceeds the Coulomb repulsion. Accordingly, fusion of nuclei becomes impossible. Only two sets of parameters (HS and NL2) provide a realistic view of the potential energy with a Coulomb barrier.

In this work, as well as in [1], using 13 reactions as an example, it is shown that TRMF forces with HS and NL2 parameters make it possible to describe high-precision experimental data on nuclear fusion cross sections with a typical error of 3-5%. The figure illustrates this result for five reactions.

Volume 85, issue 4, April 2021

Thematic issue “Physics of Cosmic Rays”

A. N. Turundaevskiy, O. A. Vasiliev, D. E. Karmanov, I. M. Kovalev, I. A. Kudryashov, A. A. Kurganov, A. D. Panov & D. M. Podorozhny, Main Results from the NUCLEON Experiment // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 4, P. 353–356.

One of the most urgent problems of cosmic ray (CR) physics now is the determination of the chemical composition of abundant CRs with the highest energy. During the beginning of the work on the NUCLEON observatory, there was a consensus regarding the behavior of the spectra of the main abundant (produced mainly in sources) nuclei up to energies no higher than several TeV. In 2014-2017 the NUCLEON space experiment was carried out. The NUCLEON is a modern high-tech spectrometer that has incorporated the advanced technologies of physical experiment. A characteristic feature of the equipment is the very insignificant consumed flight resources, such as weight, power consumption, dimensions. This is explained by the fact that a new technique for recording the energy of CR particles has been used for the first time in the spectrometer. The authors called this method KLEM (Kinematic Light – Weight Energy Meter) to emphasize its main advantage – a low-mass energy meter, which gives a gain of almost an order of magnitude in the “aperture/mass” parameter in comparison with traditional methods.

Despite the small amount of consumed resources, over 2.5 years of the orbital experiment, a data bank was obtained, including about 20 million events. This number exceeds the total statistics of all direct experiments with similar goals over the past 50 years, which made it possible to obtain spectra of abundant cosmic ray nuclei up to energies of several hundred TeV. For the first time, the integration of ground-based and orbital measurements of the CR energy spectrum took place, which made it possible to directly calibrate the data obtained in ground-based experiments. The difference of the spectrum from the power-law form at 2 – 500 TeV was statistically proved. In the energy range up to 5·1014 eV, the chemical composition of cosmic rays was determined with element-by-element resolution, and a number of features were found in the energy spectra of CR elements. The result obtained is the factual material necessary for constructing and refining models of the Galaxy and its energy balance.

The team of the authors of the article consists of the staff of the Institute of Nuclear Physics of the Moscow State University, who for many years worked on the preparation and conduct of the NUKLON experiment, and then on the processing of the results obtained. The team is one of the leading research groups in the field of cosmic ray astrophysics.

Volume 85, issue 3, March 2021

Thematic issue “Physics of Auroral Phenomena”

A. S. Nikitenko, O. M. Lebed, Yu. V. Fedorenko, J. Manninen, N. G. Kleimenova, L. I. Gromova, Localization of the Scattering Area of the Auroral Hiss by Ground-based Multipoint Measurements at High Latitudes // Bulletin of the Russian Academy of Sciences: Physics, 2021, Volume 85, Issue 3, P. 287–291.

The work is devoted to the study of the features of the exit to the Earth’s surface of natural magnetospheric electromagnetic radiation of the auroral hiss type according to ground-based observations of electromagnetic fields in the very low frequency range (VLF, from hundreds of hertz to tens of kilohertz). Auroral hiss is one example of noise emissions whose field parameters change randomly over time. Research team from the Polar Geophysical Institute has developed a method for analyzing data from ground-based observations of this kind of radiation. This method uses the representation of the field parameters as their distribution densities, while other methods use the averaged values of the field parameters. To interpret the results of ground-based observations, a numerical model of the propagation of auroral hiss radiation from the generation region to the ground-based observer is developed. The model includes the following modules: 1) generation of electrostatic waves at altitudes of 10,000 – 20,000 km; 2) propagation of electrostatic waves to the region in the ionosphere occupied by small-scale inhomogeneities of electron concentration; 3) scattering into the exit cone of electrostatic waves on small-scale inhomogeneities; 4) propagation of scattered waves in the lower ionosphere and the Earth – ionosphere waveguide.

The paper presents the results of ground-based observations of the VLF auroral hiss at three spatially separated points, Barentsburg (Svalbard Archipelago), Lovozero (Kola Peninsula, Russia) and Kannuslehto (Finland). There were cases when auroral hiss was registered only in the observatory of Barentsburg and when bursts were recorded by all three stations simultaneously. Only the collaborative use of the developed data analysis methods and the propagation model of auroral hiss allowed them to show that the burst recorded in the observatory of Barentsburg is caused by the existence of a scattering area of small-scale inhomogeneities of electron concentration which is located to the southwest of the observatory. The registration of auroral hiss bursts at all three points is caused by the simultaneous existence of two scattering areas in the ionosphere located at different latitudes.

Volume 85, issue 2, February 2021

Thematic issue “New Materials and Technologies for Security Systems”

A.M. Zarezin, P.A. Gusikhin, V.M. Muravev, S.I. Gubarev, I.V. Kukushkin, A New Family of Plasma Excitations in a Partially Gated Two-Dimensional Electron System // Bulletin of the Russian Academy of Sciences: Physics, Volume 85, Issue 2, pages 113–117 (2021)

Collective fluctuations of charge density – plasmons, have been studied in two-dimensional electronic systems (2DES) for more than 50 years. Many theoretical and experimental works have considered these excitations in 2DES of various configurations, including those with strong shielding by a closely spaced metal shutter. However, it turned out that in 2DES, only partially covered by a gate, new plasma modes are excited that differ from those previously considered and investigated. Despite its prevalence in actually studied structures, this case has been ignored for a long time. In order to study this issue, experimental work was carried out on 2DES in GaAs/AlGaAs heterostructures, partially shielded by a metal gate. This manuscript concludes a series of papers considering different geometries of the hybrid configuration of a 2DES with a gate and a contact.

Two different geometries were investigated – a 2DES disk with a central gate in the form of a disk of a smaller diameter and a perimetric contact (Corbino geometry) and a rectangular 2DES with a gate in the form of a narrow strip and side contacts. The measurements were carried out using the experimental equipment of the Laboratory of Nonequilibrium Electronic Processes of the Institute of Solid State Physics of the Russian Academy of Sciences in a cryostat with a temperature of 4.2 K and down to 1.5 K under helium vapor pumping. To detect plasma resonances, a unique optical non-invasive technique was used based on the high sensitivity of the luminescence spectrum of two-dimensional electrons to the heating of the 2DES caused by the absorption of the microwave signal.

The paper presents the results of the observation of plasma excitations in the indicated systems, obtained curves of absorption of microwave radiation depending on the frequency and applied magnetic field, and plotted the corresponding dispersion and magnetodispersive dependences. It turned out that in a 2DES with partial shielding, a family of plasma oscillations is observed that is physically different from both ordinary unshielded plasmons and plasmons in fully shielded 2DES. In addition, when the gate and contact were electrically connected, a special low-frequency mode was observed, the properties of which depend on the connected external circuit. Thus, the studies carried out have identified plasmons in partially shielded 2DES into a special family associated directly with charge oscillations in the gate and near gate regions, also containing a “tricky” hybrid mode, frequency, magnetic field behavior and Q factor of which can be changed by connecting various external electrical circuits.

Volume 85, issue 1, January 2021

Thematic issue “Wave Phenomena in Inhomogeneous Media”

I.V. Dzedolik, Linear and Nonlinear Phenomena in a Flow of Surface Plasmon–Polaritons // Bulletin of the Russian Academy of Sciences: Physics, Volume 85, Issue 1, pages 1–7 (2021)

The paper is devoted to the dynamics of electromagnetic waves at the interfaces between two media, in particular, metals and dielectrics, due to the broad prospects of using composite materials in micro- and nanodevices of photonic and plasmonic technology. A high-frequency electromagnetic field causes oscillations of both free and bound charges in dielectric, semiconducting media, and metals. In this case, as a result of charge oscillations, secondary electromagnetic waves are emitted, which hybridize with polarization waves of bound and free charges in the medium and propagate in the volume of the medium, as well as along the interface between the media in the form of plasmon-polariton waves.

An external electromagnetic field of weak intensity causes a linear response of the dielectric constant of the metal. With an increase in the amplitude of the external field, anharmonic oscillations of electrons and ions, interband transitions appear, which lead to the manifestation of nonlinear polarization mechanisms. An intense electromagnetic wave or a powerful electromagnetic pulse generates nonlinear plasmon-polariton waves – cnoidal waves, kinks and solitons in the volume of the conducting medium and at the interface between the conducting and dielectric media. The properties and dynamics of cnoidal waves and solitons depend on the parameters of the exciting electromagnetic waves and pulses, as well as on the geometry of the system and the properties of the media in which plasmon polaritons are excited.

The paper presents the results of a theoretical study of linear and nonlinear processes during the propagation of plasmon-polaritons at a plane interface between a metal and a dielectric medium, depending on the boundary conditions and the energy density of the exciting electromagnetic wave. The analysis of the dynamics of plasmon-polariton waves was carried out by solving nonlinear equations obtained on the basis of a quantum hydrodynamic model for the Schrödinger equation, which allows one to consistently describe the physical mechanisms causing the nonlinear response of free electrons in a metal to the effect of an external electromagnetic field. It is shown that the profiles of the envelopes of the plasmon-polariton cnoidal waves and their periods are transformed when the source power and/or the conditions for the excitation of plasmon-polaritons at the interface between the media change. In particular, at a certain ratio of parameters, a shock wave in the form of a kink/antikink arises. Thus, by changing the power of the source of the external electromagnetic field, it is possible to control the period and shape of a nonlinear plasmon-polariton wave propagating in plasmonic nanodevices.


Volume 84, issue 11, November 2020

A. Yu. Yurenya, A. A. Nikitin, R. R. Gabbasov, M. A. Polikarpov, V. M. Cherepanov, M. A. Chuev, M. A. Abakumov & V. Ya. Panchenko, Studying the Effect of Brownian Motion on the Mössbauer Spectra of Nanoparticles in a Medium Simulating Cell Cytoplasm // Bulletin of the Russian Academy of Sciences: Physics, Volume 84, Issue 11, pages 1399–1402 (2020)

Understanding the principles of Brownian motion of particles in solutions of macromolecules is the most important task for a number of scientific fields. In cell biophysics, one of these areas is related to the study of intracellular transport processes. Various macromolecular biopolymers, such as proteins, polysaccharides, and nucleic acids, occupy from 5 to 40 % of the volume of liquid biological media (in literature, this effect is often called macromolecular crowding), which has a significant impact on all biological processes occurring in the cell. Studying the parameters of the motion of particles and macromolecules in such conditions is extremely difficult since the details of this motion are hidden on the nanoscale. Modern experimental approaches are based on optical measurements, the research capabilities of which in relation to nanoscale objects have a number of significant limitations. Earlier, we proposed a new approach to studying the dynamics of Brownian particles. The approach is based on Mössbauer spectroscopy of nanoparticles dispersed in the studied medium and made on the basis of the 57Fe isotope. Due to the Doppler effect, the Brownian motion of nanoparticles leads to a uniform broadening of their mössbauer spectra. The diffusion coefficient of nanoparticles is directly related to the value of this broadening, which makes it possible to determine it experimentally. The time resolution of the proposed approach is determined by the lifetime of the 57Fe core excited state which is less than 10-7 s, which largely determines the uniqueness of the data obtained.

In this work, for the first time, the nanoscale motion under conditions of macromolecular crowding has been studied using the method of Mössbauer spectroscopy. In this task, we studied the motion parameters of nanoparticles with a diameter of 9 nm that are part of solutions with different contents of large-molecular BSA protein. It was shown that the availability of macromolecules in solutions with identical macroscopic viscosity slows down the average velocity of Brownian motion of nanoparticles in the nanosecond measurement range. This effect increases with the increasing concentration of macromolecules in the solution.

The Brownian motion of particles leads to a broadening of the lines of their mössbauer spectrum. The value of this broadening is directly related to the particle diffusion coefficient in the studied system, which allows us to determine its value by calculations (on the left). In accordance with the Stokes-Einstein equation, the values of the nano-viscosity were calculated from the set values of the diffusion coefficient. Even though the macroscopic viscosity of solutions with different BSA contents is identical, the actual viscosity experienced by nanoparticles depends on the concentration of BSA macromolecules (on the right).

Volume 84, issue 10, October 2020

Thematic issue “Fundamental Problems of Nuclear Physics, Nuclei at the Boundaries of Nucleon Stability, High Technologies”

L. N. Generalov & S. M. Selyankina, R-Matrix Analysis of Reactions with Excitation of the 10B Compound Nucleus at Energies of 6.5–19.5 MeV // Bulletin of the Russian Academy of Sciences: Physics, Volume 84, Issue 10, pages 1224–1233 (2020)

Interest in R-matrix studies of reactions is attracted by the possibility of searching for new ones, refining the characteristics of known shells, and evaluating the cross sections of nuclear reactions from limited sets of experimental data. This work was initiated by the appearance of new experimental data on differential cross sections of the threshold reaction 9Be(p2)6Li*.

An R-matrix analysis is performed for experimental data on 9Be(p,p0)9Be, 9Be(p,p1)9Be* (1.670 МэВ), 9Be(p,p2)9Be* (2.430 MeV), 9Be(p,n0)9B, 9Be(p,d0)8Be, 9Be(p0)6Li, 9Be(p2)6Li* (3.5618 MeV), 7Li(3He,p0)9Be reactions at 6.5–19.5 MeV excitation energies of 10B compound nucleus. Experimental data on differential and integral cross sections of the 9Be(p,α2)6Li* (3.5618 MeV, Eπ=0+) reaction at proton energy Ep = 2.3–4.5 MeV are included in the analysis, along with data on differential cross sections of the 9Be(p,n0)9B reaction at angle 0° in the Ep = 2.2–3.5 MeV energy range.

New 10B levels are determined and characteristics of states detected earlier are improved to supplement the EXFOR database.