New Publications

The effect of the impurities on the magnetic, electronic and optical properties of Mn5Ge3

Zhandun, Vyacheslav; Matsynin, Aleksey Chinese Journal Of Physics.

Earlier, we experimentally showed a significant effect of oxygen on the magnetic and structural properties of Mn5Ge3 due to the formation of a Nowotny phase of Mn5Ge3Ox. Here, in continuation of this study, we present a theoretical study of the magnetic and electronic properties of Mn5Ge3 and Mn5Ge3Dx (D = B, C, O). It was found that hexagonal Mn5Ge3 is a ferromagnetic metal with two nonequivalent manganese atoms in the structure. Our ab initio calculations also predict the existence of a spin-crossover in Mn5Ge3 under pressure. Impurities reduce saturation magnetization and electrical and thermal conductivity; however, the magnetic susceptibility and Curie temperature increase. Microscopic mechanisms of the effect of the impurities on the magnetic and electronic properties Mn5Ge3 are discussed.

Highly Porous Superconductors: Synthesis, Research, and Prospects

Gokhfeld, D. M.; Koblischka, M. R.; Koblischka-Veneva, A. Physics Of Metals And Metallography. DOI:

This paper presents a review of studies of superconductors with a porosity above 50%. The pores in such superconducting materials allow refrigerant penetration and provide efficient heat dissipation and stable operation. Methods for the synthesis of the main groups of porous superconductors are described. The results of studies of the structural, magnetic, and electrical transport properties are presented, and the features of the current flow through porous superconductors of various types are considered. The directions of further development and application of porous superconductors are presented.

A New Nonlinear Optical Selenide Crystal AgLiGa2Se4 with Good Comprehensive Performance in Mid-Infrared Region

Yelisseyev, Alexander; Lobanov, Sergei; Molokeev, Maxim; Zhang, Shengzi; Pugachev, Alexei; et al. Advanced Optical Materials.

Mid‐infrared (mid‐IR) nonlinear optical (NLO) crystals are indispensable for the mid‐IR lasers generation with tunable wavelengths from 3 to 20 µm. AgGaSe2 is a commercial mid‐IR NLO crystal with the highest figures of merit, but suffers low laser damage threshold (LDT). To achieve the balance of optical transmission, NLO effect, and LDT, it is proposed to molecularly modify the AgGaSe2 structure by introducing the [LiSe4] tetrahedra, and successfully grow large crystals of a new selenide AgLiGa2Se4. The replacement of half of the heavy Ag+ cations with light Li+ increases the band gap to 2.2 eV (vs. 1.7 eV in AgGaSe2). The LDT value in AgLiGa2Se4 increases five times compared to that in AgGaSe2, while keeping a relatively large NLO susceptibility of 26 pm V−1. Moreover, the thermal expansion coefficients in AgLiGa2Se4 are approximately two times lower in absolute value compared with AgGaSe2, which is beneficial to the large crystal growth. All these advantages would make AgLiGa2Se4 a new promising NLO crystal for mid‐IR laser applications.

Solvatochromic Photoluminescent Effects in All-Inorganic Manganese(II)-Based Perovskites by Highly Selective Solvent-Induced Crystal-to-Crystal Phase Transformations

Xiao, Hui; Dang, Peipei; Yun, Xiaohan; Li, Guogang; Wei, Yi; et al. Angewandte Chemie-international Edition.

The development of lead‐free perovskite photoelectric materials has been an extensive focus in the recent years. Herein, a novel one‐dimensional (1D) lead‐free CsMnCl3(H2O)2 single crystal is reported with solvatochromic photoluminescence properties. Interestingly, after contact with N,N‐dimethylacetamide (DMAC) or N,N‐dimethylformamide (DMF), the crystal structure can transform from 1D CsMnCl3(H2O)2 to 0D Cs3MnCl5 and finally transform into 0D Cs2MnCl4(H2O)2. The solvent‐induced crystal‐to‐crystal phase transformations are accompanied by loss and regaining of water of crystallization, leading to the change of the coordination number of Mn2+. Correspondingly, the luminescence changes from red to bright green and finally back to red emission. By fabricating a test‐paper containing CsMnCl3(H2O)2, DMAC and DMF can be detected quickly with a response time of less than one minute. These results can expand potential applications for low‐dimensional lead‐free perovskites.


Golovnev, N. N.; Molokeev, M. S.; Sterkhova, I., V; Lesnikov, M. K. Journal Of Structural Chemistry.

Organic salts with the composition NfH2(Htba)·6H2O (I) and BipyH(Htba)·2H2O (II) (Н2tba is 2-thiobarbituric acid, NfH is norfloxacin and Bipy is 2,2′-dipyridyl) are prepared. Their structures are determined by XRD (CCDC cif-file No. 1967494-1967495). Crystals I are triclinic: a = 11.8821(4) Å, b = 11.9959(5) Å, c = 12.0038(4) Å, α = 119.835(1)°, β = 107.691(1)°, γ = 95.237(1)°, V = 1351.80(9) Å3, space group P-1, Z = 2. Crystals II are monoclinic: a = 7.9587(2) Å, b = 19.6272(4) Å, c = 10.1118(2) Å, β = 98.118(1)°, V = 1563.71(6) Å3, space group P21/nZ = 4. The structures are stabilized by numerous hydrogen bonds and π–π interactions involving НtbaNfH+2NfH2+, and BipyH+ ions. Thermal decomposition of these compounds in air includes dehydration and oxidative degradation stages.

Effect of nanoparticles in growth of test - bacteria

Stolyar, S., V; Chekanova, L. A.; Yaroslavtsev, R. N.; Ladygina, V. P.; Tirranen, L. S. International Scientific Conference On Applied Physics, Information Technologies And Engineering (Apitech-2019). Journal of Physics: Conference Series, Volume 1399, Issue 2 Citation SV Stolyar et al 2019 J. Phys.: Conf. Ser. 1399 022029

Confident effect of five magnetic composite nanoparticles (FeP@Ag, FeP@Pd, CoP, NiP, Fe2O3@AГ) on growth of test bacteria colonies (Acinetobacter baumannii, Еscherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus) in five replicates each is considered. Reliable inhibitors of colonies of all five test bacteria were nanoparticles FeP@Ag. CoP nanoparticles are reliable inhibitors of growth of 4 test bacteria (except for test bacteria Escherichia сoli). NiP nanoparticles are reliable inhibitors of growth of 2 test bacteria: Escherichia сoli and Klebsiella pneumoniae. Bacteria Escherichia сoli were most sensitive to the effect of magnetic nanoparticles; and bacteria Pseudomonas aeruginosa and Staphylococcus aureus were most resistant to the effect of magnetic nanoparticles. The prospects of the method are in the possibility of multiple reuse of the magnetic particles with antimicrobial properties for bacterial decontamination of the studied sources of water and removal of magnetic nanoparticles from the treated liquids by electromagnet. The method can find use in water treatment facilities for household, Industrial and medical wastes.

The comparative analysis of the solid-state P-31 NMR spectra of Re-Pt vinylidene complexes

Smolyarov, K. T.; Volkov, N. V.; Matsulev, A. N.; Kondrasenko, A. A. International Scientific Conference On Applied Physics, Information Technologies And Engineering (Apitech-2019). Journal of Physics: Conference Series, Volume 1399, Issue 2 Citation K T Smolyarov et al 2019 J. Phys.: Conf. Ser. 1399 022028

The two vinylidene complexes Cp(CO)2 RePt(μ-C=CHPh)(PPh3 )(CO) and Cp(CO)2 RePt(μ-C=CHPh)(PPh3 )2 and their precursors PPh3 and P(PPh3 )4 were studied by solid-state nuclear magnetic resonance. We analysed 31P cross-polarization spectra acquired in static conditions and with magic angle spinning. The chemical shift tensors of each sample were determined by fitting their spectra using SIMPSON simulations.

Magnetic nanoconstructions of iron oxides coated with arabinogalactan functionalized with DNA aptamer

Stolyar, S., V; Chekanova, L. A.; Yaroslavtsev, R. N.; Komogortsev, S., V; Gerasimova, Yu, V; et al. International Scientific Conference On Applied Physics, Information Technologies And Engineering (Apitech-2019). Published under licence by IOP Publishing Ltd Journal of Physics: Conference Series, Volume 1399, Issue 2 Citation S V Stolyar et al 2019 J. Phys.: Conf. Ser. 1399 022026

New composite nanoparticles for biomedical applications have been manufactured. The particles consist of an anisomeric magnetite core coated with arabinogalactan and are functionalized with cameras for As-14 ascites cells (Ehrlich carcinoma). The binding of ascitic Ehrlich carcinoma cells to magnetic nanoparticles was evaluated using fluorescence microscopy.

Collective Spin Glass State in Nanoscale Particles of Ferrihydrite

Stolyar, S., V; Yaroslavtsev, R. N.; Ladygina, V. P.; Balaev, D. A.; Pankrats, A., I; et al. Semiconductors.

Ferromagnetic resonance was used to study three types of ferrihydrite nanoparticles: nanoparticles formed as a result of the cultivation of microorganisms Klebsiella oxytoca; chemically prepared ferrihydrite nanoparticles; chemically prepared ferrihydrite nanoparticles doped with Cu. It is established from the ferromagnetic resonance data that the frequency-field dependence (in the temperature range ТP < T < T*) is described by the expression: 2πν/γ = НR + HA(T = 0)(1 – T/Т*), where γ is the gyromagnetic ratio, HR is the resonance field. The induced anisotropy HA is due to the spin-glass state of the near-surface regions. TP temperature characterizes the energy of the interparticle interaction of nanoparticles.

Interaction of a Magnetic Vortex with Magnetic Anisotropy Nonuniformity

Orlov, V. A.; Patrin, G. S.; Orlova, I. N. Journal Of Experimental And Theoretical Physics.

The problem of propagation of a magnetic inhomogeneity in the form of a magnetic vortex near a defect simulated by a crystallite with uniaxial anisotropy has been solved theoretically. The defect (crystallite) is implanted into a homogeneous 2D ferromagnetic matrix. Apart from the anisotropy energy, the term responsible for the existence of a centrosymmetric potential is included into the total energy. For calculations, we have used the method of collective variables (Thiele equation). We have considered the variants of bidirectional and unidirectional anisotropy of the crystallite. Analysis of the equations of motion for different directions of the anisotropy axis of the implanted defect has revealed the variety in the behavior of the vortex core as a quasiparticle. The vortex core can be trapped by the defect with equilibrium position of the vortex at rest directly on the crystallite or during its motion at a certain distance from it. It is shown that for a small damping parameter and in the case when the defect anisotropy axis lies in the plane of the magnet, the vortex moves so as if its core experiences the action of the repulsive axially symmetric potential.

Features of large-scale thin foils fabrication for transmission electron microscopy by focused ion beam

Volochaev, M. N.; Shcheglova, M. S.; Balashov, Yu Yu; Loginov, Yu Yu 2020 IOP Conf. Ser.: Mater. Sci. Eng. 822 012028. doi:10.1088/1757-899X/822/1/012028

Focused ion beam (FIB) sample preparation for transmission electron microscopy is a well established technique. However there are some problems related with high-quality large-scale (over 10 um) sample preparation of thin foils. In this work we demonstrate the successful preparation of such samples on example of ferrite steel sample and present the refined lift-out preparation technique, which was applied here. All sample preparation has been carried out in conventional single-beam FIB Hitachi FB-2100 with additional low-kV Ar+ ion polishing.

Raman Spectroscopy of Crystals

Krylov, Alexander Crystals.

Raman spectroscopy is now finding wide-ranging application in pure and applied science. It can be used for the characterization of the atomic structure of solids because Raman scattering depends on the polarisation and direction of the incident light, the crystal symmetry and orientation of the solid sample, and the direction and polarisation of the scattered light. Raman spectroscopy can play a significant role in the study of crystal phase transformations, and it could involve order-disorder phenomena, polymorphs, chemical diffusion, and solid-solution shifts. One can study crystals in situ in extreme conditions—under high pressure, at high temperatures or both simultaneously, at low temperatures, or in electric or magnetic fields and extract thermodynamic data from the variations in the Raman bands with varying pressure-temperature-field conditions. Other aspects that merit attention are the possibility of analyzing nanocrystals, crystalline microinclusions under the surface, organic crystals and many others.

Experimental Study of Transport Coefficients of Aqueous Suspensions of Nanodiamonds

Pryazhnikov, M. I.; Minakov, A. V.; Lyamkin, A. I.; Red'kin, V. E.; Zharkov, S. M.; et al. Colloid Journal.

This article presents experimental data on the coefficients of viscosity and thermal and electrical conductivities, as well as the absorption spectra, of suspensions of ultradispersed diamonds. Suspensions of UDA-S and UDP-A detonation nanodiamond particles, as well as UDP-AG diamond–graphite powder, are used in the experiments. The concentration of nanodiamonds in distilled water is varied within a range of 0.5–5 wt %. It is shown that the technology of purification diamond powders from side products of their synthesis substantially affects the physicochemical properties of aqueous suspensions of these powders

Microstrip resonator for nonlinearity investigation of thin magnetic films and magnetic frequency doubler

Belyaev, B. A.; Afonin, A. O.; Ugrymov, A. V.; Govorun, I. V.; Solovev, P. N.; et al. Review Of Scientific Instruments.

A structure that consists of a λ/4 stepped-impedance microstrip resonator is proposed as an instrument for the investigation of nonlinear effects in thin magnetic films and also can be used as a microwave frequency doubler. A conversion efficiency of 0.65% is observed at a one-layer 100 nm Ni80Fe20 thin film at an input signal level of 4.6 W for a 1 GHz probe signal. The maximum measured conversion efficiency (1% at 1 GHz) was achieved for the 9-layer Ni80Fe20 film where 150 nm magnetic layers were separated by SiO2 layers

Open Fermi-Hubbard model: Landauer's versus master equation approaches

Kolovsky, Andrey R. Physical Review B. DOI:

We introduce a simple model for the quantum transport of Fermi particles between two contacts connected by a lead. It generalizes the Landauer formalism by explicitly taking into account the relaxation processes in the contacts. We calculate the contact resistance and nonequilibrium quasimomentum distribution of the carriers in the lead and show that they strongly depend on the rate of relaxation processes.

The effect of the initial microstructure of the X70 low-carbon microalloyed steel on the heat affected zone formation and the mechanical properties of laser welded joints

Gordienko, A., I; Derevyagina, L. S.; Malikov, A. G.; Orishich, A. M.; Surikova, N. S.; et al. Materials Science And Engineering A-structural Materials Properties Microstructure And Processing.

In this paper, the heat affected zone (HAZ) of laser welded joints of the X70 steel were studied by the transmission electron microscopy method. The effect of the initial microstructure (coarse-grained hot-rolled and fine-grained after cross-helical rolling) on the HAZ formation and the mechanical characteristics of the welded joints were shown. It was found that the microstructure in the inter-critical HAZ of the steel after cross-helical rolling was more dispersed, homogeneous, and uniform compared to that of the coarse-grained hot-rolled one due to the initial fine-grained ferrite-bainitic-pearlite microstructure and the absence of pronounced ferrite-pearlite banding in the base metal. The character of the microhardness value distribution in the HAZ of the steel after cross-helical rolling was smooth with the gradual decrease from 370 down to 185 HV as shifted towards the base metal. In the HAZ of the coarse-grained hot-rolled steel, the heterogeneous microhardness value (up to 640–670 НV) distribution was revealed. The reason was the upper degenerate bainite microstructure with high residual stresses, characterized by laths up to 2.0–2.5 μm long and a high martensitic-austenitic constituent fraction (10–16%) of a slender shape along the boundaries of bainite laths. The conclusion was drawn that one of the ways to reduce the brittleness of the laser welded joints could be using the initially fine-grained steels possessing the homogeneous (mainly bainitic) microstructure.

Giant resonant enhancement of optical binding of dielectric particles

Bulgakov, Evgeny N.; Pichugin, Konstantin N.; Sadreev, Almas F. Physical Review A. DOI:

Optical coupling of two identical dielectric particles gives rise to bonding and antibonding resonances. The latter is featured by significant narrowing of the resonant width and strong enhancement of the Q factor for the high-index micron-size particles in subwavelength range. We consider particles shaped as spheres and disks under coaxial illumination of dual incoherent counterpropagating Bessel beams. In the case of spheres we derive analytical expressions for the optical binding (OB) force which decays and displays two periods of oscillations. For close distances the OB force enormously increases in the resonant regime. The case of two coaxial disks is featured by extremal enhancement of the Q factor owing to the twofold variation over the distance between disks and the aspect ratio of each disk compared to the case of two spheres. In that case we demonstrate enhancement of the OB force up to several tens of nanonewtons. We show that the magnitude and sign of the OB force strongly depend on the longitudinal wave vector of the Bessel beams

Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites

Orlov, Yuri S.; Sokolov, Alexey E.; Dudnikov, Vyacheslav A.; Shulga, Karina V.; Volochaev, Mikhail N.; et al. Molecules.

We have studied, both experimentally and theoretically, the unusual temperature dependence of the phonon spectra in NdCoO3, SmCoO3 and GdCoO3, where the Co3+ ion is in the low-spin (LS) ground state, and at the finite temperature, the high-spin (HS) term has a nonzero concentration nHS due to multiplicity fluctuations. We measured the absorption spectra in polycrystalline and nanostructured samples in the temperature range 3–550 K and found a quite strong breathing mode softening that cannot be explained by standard lattice anharmonicity. We showed that the anharmonicity in the electron–phonon interaction is responsible for this red shift proportional to the nHS concentration.

Thermoelectric and Plasmonic Properties of Metal Nanoparticles Linked by Conductive Molecular Bridges

Fedorov, Aleksandr S.; Krasnov, Pavel O.; Visotin, Maxim A.; Tomilin, Felix N.; Polyutov, Sergey P. Physica Status Solidi B-basic Solid State Physics.

Thermoelectric and plasmonic properties of systems comprising small golden nanoparticles (NPs) linked by narrow conductive polymer bridges are studied using the original hybrid quantum‐classical model. The bridges are considered here to be either conjugated polyacetylene, polypyrrole, or polythiophene chain molecules terminated by thiol groups. The parameters required for the model are obtained using density functional theory and density functional tight‐binding simulations. Charge‐transfer plasmons in the considered dumbbell structures are found to possess frequency in the infrared region for all considered molecular linkers. The appearance of plasmon vibrations and the existence of charge flow through the conductive molecule, with manifestation of quantum properties, are confirmed using frequency‐dependent polarizability calculations implemented in the coupled perturbed Kohn–Sham method. To study the thermoelectric properties of the 1D periodical systems, a universal equation for the Seebeck coefficient is derived. The phonon part of the thermal conductivity for the periodical NPSC8H8–NP–S–C8H8– system is calculated by the classical molecular dynamics. The thermoelectric figure of merit ZT is calculated by considering the electrical quantum conductivity of the systems in the ballistic regime. It is shown that for Au309Au309 nanoparticles connected by polyacetylene, polypyrrole, or polythiophene chains at T = 300 K, the ZT value is {0.08;0.45;0.40}, respectively.

Magnetic anisotropy and core-shell structure origin of the biogenic ferrihydrite nanoparticles

Knyazev, Yu, V; Balaev, D. A.; Stolyar, S., V; Bayukov, O. A.; Yaroslavtsev, R. N.; et al. Journal Of Alloys And Compounds.

Ferrihydrite is a low-crystalline nanoscale matter. The uncompensated magnetic moment of the ferrihydrite caused by the antiferromagnetic ordering of the magnetic moments of iron atoms and leads to the magnetic properties very similar to those of ferro- and ferrimagnetic nanoparticles. In this study, we investigated the biogenic ferrihydrite nanoparticles with the narrow size distribution and an average diameter of 2 nm obtained by the bacteria life cycle. The features caused by the surface effects and the inhomogeneous structure of ferrihydrite have been examined in the temperature range of 4–300 K using Mössbauer spectroscopy and magnetometry. Based on the Mössbauer data, we identified the superparamagnetic blocking temperature at the temperature of 30 K for the largest ferryhidrite particles. We established that the exceptional magnetic anisotropy of ferrihydrite (KV=1.2⋅105 erg/cm3 and KS=0.1 erg/cm2) is reached because of the highly developed ferrihydrite nanoparticles’ surface. According to the Mössbauer data, we propose a core-shell structural model of the biogenic ferrihydrite particles. We found that the size of the dense core depends on the particle size. The well-crystallized core is formed only for nanoparticles larger than 2 nm, whereas smaller particles consist entirely of a matter with a lower density of iron atoms.

Magnetodielectric effect and spin state of iron ions in iron-substituted bismuth pyrostannate

Lubov Udod, Sergey Aplesnin, Maxim Sitnikov, Oxana Romanova, Oleg Bayukov, Alexander Vorotinov, Dmitriy Velikanov & Gennadiy Patrin. European Physical Journal Plus.

The magnetic and magnetodielectric properties of bismuth pyrostannate Bi2(Sn1xFex)2O7Bi2(Sn1−xFex)2O7 (x=0.1x=0.1 and 0.2) have been examined. Using the Mössbauer spectroscopy and electron paramagnetic resonance, the high-spin state and crystallographic positions of iron ions have been established. The coexistence of triclinic symmetry domains in the Bi2(Sn1xFex)2O7(x=0.1)Bi2(Sn1−xFex)2O7(x=0.1) compound with the monoclinic symmetry below 140 K has been found. For the Bi2(Sn1xFex)2O7Bi2(Sn1−xFex)2O7 composition with x=0.2x=0.2, the nonlinear field dependence of magnetization in the paramagnetic region up to room temperatures has been observed. The electric polarization hysteresis and the magnetoelectric effect in the Bi2(Sn1xFex)2O7Bi2(Sn1−xFex)2O7 compound have been disclosed. The magnetic field-dependent anomalous behavior of magnetization has been explained by the magnetoelectric effect.

Comparative analysis of elastocaloric and barocaloric effects in single-crystal and ceramic ferroelectric (NH4)(2)SO4

Mikhaleva, Ekaterina; Gorev, Mikhail; Bondarev, Vitaly; Bogdanov, Evgeny; Flerov, Igor. Scripta Materialia.

We report the influence of anisotropy and texture on elasto(ElCE)- and baro(BCE)-caloric effects in single-crystal and ceramic (NH4)2SO4. Inverse extensive and intensive ElCE in ceramics, (ΔSElCE)cer = 87 J/kg·K; ΔTAD = - 11.6 K), as well as in a single crystal along the ferroelectric axis a, (ΔSElCE)a = 115 J/kg·K; (ΔTAD)a = - 16 K, significantly exceed BCE, ΔSBCE = 75 J/kg·K; ΔTAD = - 9.8 K, even at low pressure ~ 0.3 GPa. Caloric parameters of ammonium sulphate are comparable with those for promising solid-state refrigerants.

Giant resonant enhancement of optical binding of dielectric disks

Bulgakov, E. N.; Pichugin, K. N.; Sadreev, A. F. Journal Of The Optical Society Of America B-optical Physics.

Two-fold variation over the aspect ratio of each disk and distance between disks gives rise to numerous events of avoided crossing of resonances of individual disks. For these events, the hybridized anti-bonding resonant modes can acquire a morphology close to the Mie resonant mode with the high orbital momentum of an equivalent sphere. The 𝑄Q factor of such resonance can exceed the 𝑄Q factor of an isolated disk by two orders of magnitude. We show that dual incoherent counterpropagating coaxial Bessel beams with power 1mW/µm21mW/µm2 with frequency resonant to such anti-bonding Mie-like modes result in unprecedented optical binding forces up to tens of nano-Newtons for silicon micrometer-sized disks. We show also that the magnitude and sign of optical forces depend strongly on the longitudinal wave vector of the Bessel beams.

Experimental Study of Transport Coefficients of Aqueous Suspensions of Nanodiamonds

M. I. Pryazhnikov, A. V. Minakov, A. I. Lyamkin, V. E. Red’kin, S. M. Zharkov & G. M. Zeer. Colloid Journal.

This article presents experimental data on the coefficients of viscosity and thermal and electrical conductivities, as well as the absorption spectra, of suspensions of ultradispersed diamonds. Suspensions of UDA-S and UDP-A detonation nanodiamond particles, as well as UDP-AG diamond–graphite powder, are used in the experiments. The concentration of nanodiamonds in distilled water is varied within a range of 0.5–5 wt %. It is shown that the technology of purification diamond powders from side products of their synthesis substantially affects the physicochemical properties of aqueous suspensions of these powders.

Ultrafast Quantum Relaxation Dynamics of Magnetically Ordered Systems with Spin Crossover in an Excited State under a Sudden Perturbation

Orlov, Yu. S.; Nikolaev, S. V.; Ovchinnikov, S. G.; Nesterov, A. I. Jetp Letters.

A theoretical model based on the relaxation equation for the density matrix has been proposed to describe the ultrafast time dynamics of magnetically ordered systems with spin crossover in an excited state under a sudden perturbation. Oscillations of the magnetization, the population of the high-spin state, and the generation of local vibrons at a transition of the system from the light-excited Franck-Condon low-spin state to the highspin ground state.

Mechanisms of the Insulator-Metal Transition and Spin Crossover in CoO at High Pressure

Gavrichkov, V. A.; Orlov, Yu. S.; Ovchinnikova, T. M.; Ovchinnikov, S. G. Jetp Letters.

The effect of high pressure on the electronic characteristics of CoO is analyzed in the framework of the multielectron model of transition metal oxides. The specific features of spin crossover for d7 terms of Co2+ are compared to those characteristic of d5 and d6 configurations. A pressure-induced transition between antiferromagnetic and ferromagnetic states at the spin crossover point is predicted. A model is proposed to describe the pressure-induced variation of the electrical resistance exhibiting a stepwise change by eight orders of magnitude at the structural transition point observed at 43 GPa and the subsequent metallization above 133 GPa.

Synthesis, Structure, and Thermophysical Properties of Pb10- Bi-x(x)(GeO4)(2+) xVO4)(4-) (x) (x=0-3) in the Temperature Range of 350-950 K

Denisova, L. T.; Molokeev, M. S.; Denisov, V. M.; Golubeva, E. O.; Galiakhmetova, N. A. Physics Of The Solid State.

The Pb10 - Bi-x(x)(GeO4)(2 +) (x)(VO4)(4 -) (x) (x = 0-3) compounds with an apatite structure have been obtained for the first time from the initial PbO, Bi2O3, GeO2, and V2O5 oxides by the solid-state synthesis in the temperature range ...

Tolerance Factor for Huntite-Family Compounds

Molokeev, M. S.; Kuznetsov, S. O. Physics Of The Solid State.

85 RM3(BO3)4 (R is the rare-earth element (Y, La–Lu) and M = Al, Sc, Cr, Fe, or Ga) compounds with the huntite structure have been analyzed. The analysis of the structures has made it possible to determine critical atomic displacements during the phase transition R32 ↔ P3121 and establish how these critical displacements can be controlled by varying the ionic radii. A tolerance factor has been derived and its threshold value below which the structure is stable in the R32 phase and above it, in the distorted P3121 phase, has been found. The formula has been tested on more than 30 huntite-family compounds and good agreement has been obtained. Therefore, it can be used with confidence to predict new compounds. At the moment, the tolerance factor has allowed us to establish previously unknown regularities in huntites.

Forming High-Temperature Superconducting Layers at the Interfaces between Nonsuperconducting Phases

Petrov, M. I.; Popkov, S. I.; Terent'ev, K. Yu.; Vasil'ev, A. D. Technical Physics Letters.

An alternative technique for synthesizing high-temperature superconductor samples is proposed, in which superconducting layers should form on the surface of hard-melting Ho2BaCuO5 green phase grains immersed in the liquid phase BaCuO2 + CuO.

A Bandpass Filter-Polarizer Based on a Dielectric Multilayer with Strip Conductor Gratings

Belyaev, B. A.; Tyurnev, V. V.; Voloshin, A. S.; Leksikov, An. A.; Galeev, R. G., V. F. Shabanov Doklady Physics.

A new design of a multilayer bandpass filter is proposed, in which each resonator consists of two identical dielectric layers with parallel strip conductor gratings on their outer surfaces and an orthogonal strip conductor grating between the layers. The filter designed on the basis of crossed gratings works simultaneously as a polarizer transparent in a specified frequency band if the electric field vector of a wave is parallel to the outer strip conductors but reflects waves with an orthogonal polarization. The data from a numerical electrodynamic analysis of a 3D model of the proposed device agree well with the results of the measurements performed on the fifth-order filter–polarizer prototype with a relative bandwidth of 14% and a central frequency of 13.4 GHz. The microwave power loss in the filter passband is ~1.2 dB under parallel polarization of the electromagnetic wave and more than 40 dB under orthogonal polarization.

Document Actions