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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Romanova O. B., Kretinin V. V., Aplesnin S. S., Sitnikov M. N., Udod L. V., Yanushkevich K. I.
Заглавие : Electrical properties of the polycrystalline BiFe0.95Co0.05O3 films
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Belarusian Republican Foundation for Basic Research [20-52-00005]
Место публикации : Phys. Solid State. - 2021. - Vol. 63. Is. 6. - P.897-903. - ISSN 1063-7834, DOI 10.1134/S1063783421060184. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 34. - This study was supported by the Russian Foundation for Basic Research and the Belarusian Republican Foundation for Basic Research, project no. 20-52-00005
Предметные рубрики: BiFeO3 THIN-FILMS
PHASE-SEPARATION
CRYSTAL
MODEL
Аннотация: Semiconductor BiFe0.95Co0.05O3 thin-film compounds have been synthesized by a burst technique. The film surface morphology and the effect of electronic doping via substitution of cobalt ions for trivalent iron on the optical, magnetic, and kinetic properties have been investigated in the temperature range of 77-600 K in magnetic fields of up to 12 kOe. Two electron relaxation channels have been found in the impedance spectrum in the frequency range of 0.1-1000 kHz. The negative magnetoresistance in the anomalous magnetization region and the maximum magnetoimpedance in the vicinity of the surface phase transition have been established. Using the Hall measurements, carrier types dominating in the magnetoresistance and magnetoimpedance effects have been determined. The magnetization anomalies have been explained in the model of superparamagnetic clusters and the magnetoresistance, by the carrier scattering by spin fluctuations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Zeyliger, Anatoly
Заглавие : Application of Sentinel-1B polarimetric observations to soil moisture retrieval using neural networks: Case study for bare Siberian chernozem soil
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-29-05261 mk]; Ministry of Science and Higher Education of the Russian Federation [0287-2021-0034]
Место публикации : Remote Sens. - 2021. - Vol. 13, Is. 17. - Ст.3480. - ISSN 2072-4292(eISSN), DOI 10.3390/rs13173480
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research (grant No. 19-29-05261 mk). The field experiment and EC-5 Decagon sensor calibration in laboratory conditions were carried out with the support of Ministry of Science and Higher Education of the Russian Federation, project No. 0287-2021-0034 (basic state assignment)
Предметные рубрики: SURFACE
MODEL
PARAMETERS
ROUGHNESS
INVERSION
DUBOIS
IEM
OH
Аннотация: Sentinel-1 is currently the only synthetic-aperture radar, which radar measurements of the earth’s surface to be carried out, regardless of weather conditions, with high resolution up to 5–40 m and high periodicity from several to 12 days. Sentinel-1 creates a technological platform for the development of new globally remote sensing algorithms of soil moisture, not only for hydrological and climatic model applications, but also on a single field scale for individual farms in precision farming systems used. In this paper, the potential of soil moisture remote sensing using polarimetric Sentinel-1B backscattering observations was studied. As a test site, the fallow agricultural field with bare soil near the Minino village (56.0865°N, 92.6772°E), Krasnoyarsk region, the Russian Federation, was chosen. The relationship between the cross-polarized ratio, reflectivity, and the soil surface roughness established Oh used as a basis for developing the algorithm of soil moisture retrieval with neural networks (NNs) computational model. Two NNs is used as a universal regression technique to establish the relationship between scattering anisotropy, entropy and backscattering coefficients measured by the Sentinel-1B on the one hand and reflectivity on the other. Finally, the soil moisture was found from the soil reflectivity in solving the inverse problem using the Mironov dielectric model. During the field campaign from 21 May to 25 August 2020, it was shown that the proposed approach allows us to predict soil moisture values in the layer thickness of 0.00–0.05 m with the root-mean-square error and determination coefficient not worse than 3% and 0.726, respectively. The validity of the proposed approach needs additional verification on a wider dataset using soils of different textures, a wide range of variations in soil surface roughness, and moisture.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Togushova Yu. N., Dolgov, O., V
Заглавие : Decisive proofs of the s± → s++ transition in the temperature dependence of the magnetic penetration depth
Коллективы : Russian Foundation for Basic Research (RFBR)Russian Foundation for Basic Research (RFBR) [19-32-90109]; RFBRRussian Foundation for Basic Research (RFBR); Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science to the Research Projects 'Electronic correlation effects and multiorbital physics in iron-based materials and cuprates' [19-42-240007]
Место публикации : Supercond. Sci. Technol. - 2021. - Vol. 34, Is. 7. - Ст.075008. - ISSN 0953-2048, DOI 10.1088/1361-6668/abff6f. - ISSN 1361-6668(eISSN)
Примечания : Cited References: 40. - We are grateful to D V Efremov, A S Fedorov, S G Ovchinnikov, E I Shneyder, D Torsello, and A N Yaresko for useful discussions. This work was supported in part by the Russian Foundation for Basic Research (RFBR) Grant No. 19-32-90109 and by RFBR and Government of Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science to the Research Projects 'Electronic correlation effects and multiorbital physics in iron-based materials and cuprates' Grant No. 19-42-240007.
Предметные рубрики: ORDER-PARAMETER
IMPURITIES
SUPERCONDUCTORS
STATES
MODEL
Аннотация: One of the features of the unconventional s± state in iron-based superconductors is possibility to transform to the s++ state with the increase of the nonmagnetic disorder. Detection of such a transition would prove the existence of the s± state. Here we study the temperature dependence of the London magnetic penetration depth within the two-band model for the s± and s++ superconductors. By solving Eliashberg equations accounting for the spin-fluctuation mediated pairing and nonmagnetic impurities in the T-matrix approximation, we have derived a set of specific signatures of the s± → s++ transition: (1) sharp change in the behavior of the penetration depth λL as a function of the impurity scattering rate at low temperatures; (2) before the transition, the slope of ΔλL(T) = λL(T) - λL(0) increases as a function of temperature, and after the transition this value decreases; (3) the sharp jump in the inverse square of the penetration depth as a function of the impurity scattering rate, λL-2(Γa), at the transition; (4) change from the single-gap behavior in the vicinity of the transition to the two-gap behavior upon increase of the impurity scattering rate in the superfluid density ρs(T).
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhou, Guojun, Guo, Shaoqiang, Zhao, Jing, Molokeev M. S., Liu, Quanlin, Zhang, Junying, Xia, Zhiguo
Заглавие : Unraveling the mechanochemical synthesis and luminescence in MnII-based two-dimensional hybrid perovskite (C4H9NH3)2PbCl4
Место публикации : Sci. China Mater. - 2019. - Vol. 62, Is. 7. - P.1013-1022. - ISSN 2095-8226, DOI 10.1007/s40843-018-9404-4. - ISSN 2199-4501(eISSN)
Примечания : Cited References: 40. - The present work was supported by the National Natural Science Foundation of China (91622125, 51722202 and 51572023) and the Natural Science Foundation of Beijing (2172036), and Molokeev M acknowledges the support of the Russian Foundation for Basic Research (17-52-53031). The DFT calculation was carried out at the National Supercomputer Center in Tianjin, and the calculations were performed on TianHe-1(A).
Предметные рубрики: DOPANT ENERGY-TRANSFER
EMISSION
EXCITON
MODEL
Аннотация: The mechanochemical route is a facile and fast way and has received much attention for developing versatile advanced functional materials. Herein, we reported a mechanochemical synthesis for incorporating divalent manganese ions (MnII) into a two-dimensional (2D) hybrid perovskite (C4H9NH3)2PbCl4. The mild external stimuli originating from the grinding at room temperature enabled the formation of MnII-doped 2D hybrid perovskites, and rapidly changed the luminescence characteristics. The photoluminescence analyses show that the violet and orange emissions are attributed to (C4H9NH3)2Pb1–xMnxCl4 band-edge emission and the T1→6A1 transition of Mn2+ resulting from an efficient energy transfer process, respectively. Site preference and distribution of the doped Mn2+ cations on the locations of Pb2+ were analyzed. The formation energy calculated by the density functional theory (DFT) indicates that the Mn2+ ions can rapidly enter the crystal lattice due to the unique 2D crystal structure of the hybrid perovskite. Such a case of mechanochemical synthesis for the 2D hybrid perovskite motivates many novel emerging materials and the related applications.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Kirillov V. L., Bayukov O. A., Mart'yanov O. N.
Заглавие : Mossbauer spectroscopy study of the superparamagnetism of ultrasmall ε-Fe2O3 nanoparticles
Коллективы : Russian Science Foundation [17-12-01111]
Место публикации : JETP Letters. - 2018. - Vol. 108, Is. 8. - P.527-531. - ISSN 0021-3640, DOI 10.1134/S0021364018200092. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 22. - This work was supported by the Russian Science Foundation (project no. 17-12-01111).
Предметные рубрики: High-temperature
Particles
ε-Fe2O3
Phase
Model
Аннотация: The superparamagnetism of an ensemble of ϵ-Fe2O3 nanoparticles with a mean size of 3.9 nm dispersed in a xerogel SiO2 matrix is studied by the Mössbauer spectroscopy method. It is shown that most nanoparticles at room temperature are in the superparamagnetic (unblocked) state. As the temperature decreases, the progressive blocking of the magnetic moments of the particles occurs, which is manifested in the Mössbauer spectra as the transformation of the quadrupole doublet into a Zeeman sextet. The analysis of the relative intensity of the superparamagnetic (quadrupole doublet) and magnetically split (sextets) spectral components in the range of 4–300 K provides the particle size distribution, which is in agreement with the transmission electron microscopy data. The values of the effective magnetic anisotropy constants (Keff) are determined, and the contribution of surface anisotropy (KS) is estimated for particles of various sizes. It is shown that the quantity Keff is inversely proportional to the particle size, which indicates the significant contribution of the surface to the magnetic state of the ϵ-Fe2O3 nanoparticles with the size of several nanometers.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Topological phase transitions in tilted optical lattices
Место публикации : Phys. Rev. A. - 2018. - Vol. 98, Is. 1. - Ст.013603. - ISSN 2469-9926, DOI 10.1103/PhysRevA.98.013603. - ISSN 2469-9934(eISSN)
Примечания : Cited References: 17
Предметные рубрики: BLOCH OSCILLATIONS
REALIZATION
BANDS
MODEL
Аннотация: We analyze the energy spectrum and eigenstates of cold atoms in a tilted brick-wall optical lattice. When the tilt is applied, the system exhibits a sequence of topological phase transitions reflected in an abrupt change of the eigenstates. It is demonstrated that these topological phase transitions can be easily detected in a laboratory experiment by observing Bloch oscillations of cold atoms.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Val'kova T. A., Mitskan V. A.
Заглавие : Effect of the three-center terms on the chiral superconducting d-wave pairing of the Hubbard fermions on the triangular lattice
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440. - P.129-132. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.085
Примечания : Cited References: 14. - The reported study was funded by the Russian Foundation for Basic Research, project no. 16-02-00073 and by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project no. 16-42-240435.
Предметные рубрики: MODEL
Ключевые слова (''Своб.индексиров.''): superconductivity--chiral order parametr--triangular lattice
Аннотация: Using the diagram technique for the Hubbard operators an integral equation that determines the order parameter of the superconducting phase Δ(p) was obtained in the framework of t−J−V and t−J*−V models on triangular lattice. It is shown that there are two scenarios of formation of superconducting phase with gapless spectrum at the critical concentration of carriers xc. The effect of three-center terms on implementation of this phase was also considered.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan, M. Yu., Val'kov V. V., Aksenov S. V.
Заглавие : Coulomb interactions-induced perfect spin-filtering effect in a quadruple quantum-dot cell
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440: EURO-Asian Symposium on Trends in Magnetism (EASTMAG) (AUG 15-19, 2016, Siberian Fed Univ, Krasnoyarsk, RUSSIA). - P.15-18. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.106. - ISSN 1873-4766(eISSN)
Примечания : Cited References:29. - We acknowledge fruitful discussions with P.I. Arseyev, N.S. Maslova, V.N. Mantsevich and R.Sh. Ikhsanov. This work was supported by the Comprehensive programme SB RAS no. 0358-2015-0007, the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research projects nos. 15-02-03082, 16-42-243056, 16-42-242036, 17-42-240441. M.Yu.K. thanks the Program of Basic Research of the National Research University Higher School of Economics for support.
Предметные рубрики: SPINTRONICS
TRANSPORT
MODEL
Ключевые слова (''Своб.индексиров.''): spin filter--quantum interference--fano-feshbach resonance--coulomb--correlations
Аннотация: A quadruple quantum-dot (QQD) cell is proposed as a spin filter. The transport properties of the QQD cell were studied in linear response regime on the basis of the equations of motion for retarded Green's functions. The developed approach allowed us to take into account the influence of both intra-and interdot Coulomb interactions on charge carriers' spin polarization. It was shown that the presence of the insulating bands in the conductance due to the Coulomb correlations results in the emergence of spin-polarized windows (SPWs) in magnetic field leading to the high spin polarization. We demonstrated that the SPWs can be effectively manipulated by gate fields and considering the hopping between central dots in both isotropic and anisotropic regimes.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S.
Заглавие : The modification of low-temperature magnetic properties of the Fe-based double-zigzag single-chain magnet under irradiation
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440. - P.19-22. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.100
Примечания : Cited References: 14. - This study was supported by the Presidium of the Russian Academy of Sciences, program Actual problems of low temperature physics (project 0358-2015-0005); the Russian Foundation for Basic Research, projects nos. 16-42-243057 (partly with Government of Krasnoyarsk Territory) and 15-42-04372; Technology Support Fund to the research project nos. 14/16. The work of M.S.S. was supported by grant of the President of the Russian Federation (project MK-1398.2017.2).
Предметные рубрики: SPIN-CROSSOVER
MODEL
Ключевые слова (''Своб.индексиров.''): single-chain magnets--light-induced spin crossover--magnetic susceptibility--quantum phase transitions
Аннотация: An exact solution for a generalized Ising model describing single-chain magnet {[FeIII(Tp*)(CN)3]2FeII(bpmh)}·2H2O with alternating high-spin and low-spin iron ions and double-zigzag magnetic topology has been calculated making use of the transfer-matrix technique. The introduction of a statistical ensemble taking into account the presence of iron ions with high-spin (HS) and low-spin (LS) states made it possible to describe the modification of magnetic susceptibility under optical irradiation. It has been shown that joint implementation of iron ions with photoinduced magnetic states and non-magnetic intersite repulsion ions of these states is caused by the difference of the ionic radii of HSFeIIHSFeII and LSFeIILSFeII leads to the quantum phase transitions in the system.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Bose-Hubbard Hamiltonian: Quantum chaos approach
Место публикации : Int. J. Mod. Phys. B: World Scientific Publishing, 2016. - Vol. 30, Is. 10. - Ст.1630009. - ISSN 0217-9792, DOI 10.1142/S0217979216300097. - ISSN 1793-6578(eISSN)
Примечания : Cited References:42
Предметные рубрики: Optical lattice
Dynamics
Atoms
States
Model
Ключевые слова (''Своб.индексиров.''): cold atoms in optical lattices--quantum transport--nonlinear dynamics and chaos
Аннотация: We discuss applications of the theory of quantum chaos to one of the paradigm models of many-body quantum physics - the Bose-Hubbard (BH) model, which describes, in particular, interacting ultracold Bose atoms in an optical lattice. After preliminary, pure quantum analysis of the system we introduce the classical counterpart of the BH model and the governing semiclassical equations of motion. We analyze these equations for the problem of Bloch oscillations (BOs) of cold atoms where a number of experimental results are available. The paper is written for nonexperts and can be viewed as an introduction to the field.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Origin of the spin polaron quasiparticles and their cooper instability in High-Tc superconductors
Коллективы : Russian Foundation for Basic Research [13-02-00523, 13-02-00909]; Dynasty Foundation
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1049-1055. - ISSN 1557-1939, DOI 10.1007/s10948-016-3383-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:15. - This study was supported by the Russian Foundation for Basic Research, projects nos. 13-02-00523, 13-02-00909 and the Dynasty Foundation.
Предметные рубрики: Model
State
Ключевые слова (''Своб.индексиров.''): cuprate high-t-c superconductors--spin polarons--spin-fermion model
Аннотация: IIn the framework of the spin-fermion model, it is shown that accounting for the strong spin-charge fluctuations between holes of copper and oxygen ions in cuprate High-T c superconductors leads to the formation of the Fermi spin-polaron quasiparticles. It is demonstrated that the large value of the binding energy of such quasiparticle is determined by the processes in which hopping intensity of the oxygen holes depends significantly on the spin configuration of holes on the copper and oxygen ions. It was found that the ensemble of such quasiparticles manifests Cooper instability and the concentration dependence of the critical temperature is in good agreement with the experimental data.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Patrin G. S., Shiyan Ya. G., Patrin K. G., Yurkin G. Yu.
Заглавие : Synthesis and magnetic properties of [(CoP)soft/NiP/(CoP)hard/NiP]n films
Место публикации : J. Low Temp. Phys.: Springer, 2016. - Vol. 182, Is. 3-4. - P.73-81. - ISSN 00222291 (ISSN), DOI 10.1007/s10909-015-1363-1
Примечания : Cited References: 25. - This study was supported by the Ministry of Education and Science of the Russian Federation for the Siberian Federal University, state Order No. 3.2534.2014/K and the Russian Foundation for Basic Research, Project No. 14-02-00238-a.
Предметные рубрики: Exchange
Phase
Model
Ключевые слова (''Своб.индексиров.''): interlayer coupling--magnetic heterostructure--hysteresis loop--interlayer coupling--magnetic spring
Аннотация: Magnetic interactions in Co–Ni–P multilayers consisting of alternating magnetically soft and magnetically hard layers are experimentally investigated. The variation in the shape of magnetization loops at the conjugation of magnetically soft and magnetically hard layers and the saturation field oscillations with varying number of layer pairs are established. It is demonstrated that insertion of a nonmagnetic spacer significantly affects the magnetization reversal in the structure. It is concluded that in studying the interlayer coupling it is necessary to take into account the biquadratic interaction.
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13.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Mironov V. L., Shvaleva A., Muzalevskiy K. V.
Заглавие : Measuring Soil Temperature and Moisture of Arctic Tundra Based on SMOS and ALOS PALSAR data
Место публикации : International Siberian Conference on Control and Communications (SIBCON) (MAY 21-23, 2015, Omsk, RUSSIA): IEEE, 2015. - ISBN 978-1-4799-7103-9
Примечания : Cited References:11
Предметные рубрики: MODEL
Ключевые слова (''Своб.индексиров.''): smos--alos palsar--soil moisture--soil temperature--permafrost--artic--tundra
Аннотация: In this paper, methods for retrieving soil moisture, roughness, and temperature based on the radar backscatter coefficient (ALOS PALSAR) and brightness temperature (SMOS) data related to a tundra area on the Yamal peninsula were tested. As theoretical models, there were used the semi-empirical backscatter model proposed by Y. Oh et. al and the Lband Microwave Emission of the Biosphere (L-MEB) model proposed by J-P Wigneron et. al. An integral part of these models is a permittivity model of moist soil both thawed and frozen, which links backscatter coefficient and brightness temperature with moisture, temperature, and dry density of the soil as well as the wave frequencies used by the ALOS PALSAR and SMOS. The applied permittivity model was developed based on dielectric measurements conducted for the organic rich soil samples collected at the Vaskiny Dachi weather station located in the area of the radar backscatter and brightness observations. The retrieved temperatures were correlated with the ones measured at the weather station yielding the values of root-mean-square error and determination coefficient of 3.8 degrees C and 0.80, respectively.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Spitaler J., Kokorina E. E., Nekrasov I. A., Gavrichkov V. A., Draxl C., Ovchinnikov S. G.
Заглавие : Coupling of Hubbard fermions with phonons in La2 CuO4: A combined study using density-functional theory and the generalized tight-binding method
Место публикации : J. Alloys Compd.: Elsevier, 2015. - Vol. 648. - P.258-264. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2015.05.150
Примечания : Cited References: 60. - We acknowledge the stimulating discussions with V.V. Val'kov, D.M. Dzebisashvilly, M.M. Korshunov and I.S. Sandalov. E.I.S. and S.G.O. are thankful to the Russian Science Foundation (project No. 14-12-00061) for the support of the research given in Sections 2, 6 and 7. E.E.K. and I.A.N. are thankful to the State Contract No. 0389-2014-0001 and RFBR grant No. 14-02-00065 for the support of the research given in Section 5. Financial support of the research given in Sections 3 and 4 by the Austrian Federal Government (in particular from Bundesministerium fur Verkehr, Innovation und Technologie and Bundesministerium fur Wissenschaft, Forschung und Wirtschaft) represented by Osterreichische Forschungsforderungsgesellschaft mbH and the Styrian and the Tyrolean Provincial Government, represented by Steirische Wirtschaftsforderungsgesellschaft mbH and Standortagentur Tirol, within the framework of the COMET Funding Programme is gratefully acknowledged by C.D. and J.S.
Предметные рубрики: MEAN-FIELD THEORY
LINEAR-RESPONSE THEORY
CUPRATE SUPERCONDUCTORS
ELECTRONIC-STRUCTURE
CORRELATED SYSTEMS
LATTICE-DYNAMICS
BAND-STRUCTURE
LA2CUO4
MODEL
LA2-XSRXCUO4
Ключевые слова (''Своб.индексиров.''): high-temperature superconductivity--electron-phonon coupling--density-functional theory--generalized tight-binding approach
Аннотация: We present results for the electron-phonon interaction of the Γ-point phonons in the tetragonal high-temperature phase of La2 CuO4 obtained from a hybrid scheme, combining density-functional theory (DFT) with the generalized tight-binding approach. As a starting point, eigenfrequencies and eigenvectors for the Γ-point phonons are determined from DFT within the frozen phonon approach utilizing the augmented plane wave + local orbitals method. The so obtained characteristics of electron-phonon coupling are converted into parameters of the generalized tight-binding method. This approach is a version of cluster perturbation theory and takes the strong on-site electron correlations into account. The obtained parameters describe the interaction of phonons with Hubbard fermions which form quasiparticle bands in strongly correlated electron systems. As a result, it is found that the Γ-point phonons with the strongest electron-phonon interaction are the A2u modes (236 cm-1, 131 cm-1 and 476 cm-1). Finally it is shown, that the single-electron spectral-weight redistribution between different Hubbard fermion quasiparticles results in a suppression of electron-phonon interaction which is strongest for the triplet Hubbard band with z oriented copper and oxygen electrons. © 2015 Elsevier B.V. All rights reserved.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bobrov P. P., Mironov V. L., Repin A. V.
Заглавие : Dielectric permittivity spectra of oil-water-saturated sandy-clayey rocks of different mineralogical compositions and relaxation properties of water in these rocks
Коллективы : RFBR [12-05-00502a, 14-05-00151a]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2015. - Vol. 56, Is. 7. - P.1065-1073. - ISSN 1068-7971, DOI 10.1016/j.rgg.2015.06.007
Примечания : Cited References: 21. - This work was supported by RFBR (grant nos. 12-05-00502a and 14-05-00151a).
Предметные рубрики: MOIST SOILS
FREQUENCY
MODEL
TEMPERATURE
SALINITY
RANGE
GHZ
Ключевые слова (''Своб.индексиров.''): conductivity--dielectric permittivity--multifrequency dielectric relaxation--oil-bearing deposits--sandy-clayey rocks
Аннотация: Experimental measurements of the dielectric permittivity and equivalent conductivity of sandy-clayey samples (a mixture of river sand with bentonite or kaolin) saturated with salt-solution-diesel-fuel emulsions were performed in the frequency range from 10 kHz to 1 GHz at temperatures of 25-65 °C. It is shown that when the content of the salt solution in the saturating fluid does not exceed 10%, the dielectric permittivity in the frequency range from 1 MHz to 1 GHz depends little on the mineral composition of the sample and on the concentration of the saturating solution. When the portion of water is 33.3% or higher, increasing the concentration of the salt solution leads to an increase in the equivalent conductivity and the real part of the complex dielectric permittivity. Using the refractive model of the complex dielectric permittivity, we have estimated the dielectric properties of bound water, which depend on temperature and the type of clay (bentonite or kaolin) in the sand-clay mixture but are independent of the water saturation and the amount of clay in the sample.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Temperature dependence of the electronic structure of La2CuO4 in the multielectron LDA+GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 121, Is. 3. - P.457-464. - ISSN 1063-7761, DOI 10.1134/S1063776115090174
Примечания : Cited References: 38. - The work was supported by the Russian Science Foundation (project no. 14-12-00061)
Предметные рубрики: Copper oxides
Model
Superconductivity
Excitations
Instability
Spectrum
States
Order
Аннотация: The band structure of La2CuO4 in antiferromagnetic and paramagnetic phases is calculated at finite temperatures by the multielectron LDA+GTB method. The temperature dependence of the band spectrum and the spectral weight of Hubbard fermions is caused by a change in the occupation numbers of local multielectron spin-split terms in the antiferromagnetic phase. A decrease in the magnetization of the sublattice with temperature gives rise to new bands near the bottom of the conduction band and the top of the valence band. It is shown that the band gap decreases with increasing temperature, but La2CuO4 remains an insulator in the paramagnetic phase as well. These results are consistent with measurements of the red shift of the absorption edge in La2CuO4 with increasing temperature. © 2015, Pleiades Publishing, Inc.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Nature of Cooper instability of spin polarons in cuprate high-Tc superconductors
Коллективы : Russian Foundation for Basic Research [13-02-00523, 13-02-00909], Dynasty Foundation
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2015. - Vol. 181, Is. 3-4. - P.134-138. - ISSN 0022, DOI 10.1007/s10909-015-1331-9. - ISSN 15737357(eISSN)
Примечания : Cited References:10. - This study was supported by the Russian Foundation for Basic Research, Projects Nos. 13-02-00523, 13-02-00909 and the Dynasty Foundation.
Предметные рубрики: OXIDES
MODEL
Ключевые слова (''Своб.индексиров.''): high-t-c superconductors--spin polarons--spin-fermion model
Аннотация: It is shown that the exchange interaction in the subsystem of localized moments of copper ions can trigger a Cooper instability in the ensemble of spin-polaron quasiparticles in cuprate high-temperature superconductors. It is important that, inherent to cuprates, strong coupling between Fermi and spin degrees of freedom leads on the one hand to formation of spin-polaron quasiparticles and, on the other hand, allows to transfer the interaction between Bose degrees of freedom onto the interaction between Fermi quasiparticles. The solution of the integral equation for the d-wave superconducting order parameter is well consistent with the available experimental data.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dzebisashvili D. M., Val'kov V. V., Barabanov A. F.
Заглавие : Fermi surface evolution in the ensemble of spin-polarized quasiparticles in La2 - xSrxCuO4
Место публикации : JETP Letters. - 2014. - Vol. 98, Is. 9. - P.528-533. - ISSN 0021-3640, DOI 10.1134/S0021364013220049. - ISSN 1090-6487
Примечания : Cited References: 36. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Mesoscopic and Disordered Structures"), by the Russian Foundation for Basic Research (project nos. 13-02-00909, 13-02-00523, and 11-02-98007-Siberia), and by the Dynasty Foundation.
Предметные рубрики: SADDLE-POINT SINGULARITY
ANTIFERROMAGNETIC CORRELATIONS
CUPRATE SUPERCONDUCTORS
NORMAL-STATE
MODEL
BI2SR2CACU2O8+DELTA
YBA2CU3O6.9
LA2CUO4
EXCITATIONS
YBA2CU4O8
Аннотация: For the spin-fermion model, it has been shown that the concept of spin polarons makes it possible to reproduce fine details of the Fermi surface evolution in the nodal direction of La2-xSrxCuO4 occurring with changes in the doping level x. The physics here is determined by the spin-correlated hopping of charge carriers and by the doping dependence of the inverse magnetic correlation length. © 2013 Pleiades Publishing, Inc.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S.
Заглавие : Radiation-induced modification of the temperature dependence of the magnetic susceptibility of a 1D magnet
Коллективы : Russian Foundation for Basic Research [12-02-31130, 13-02-00523, 13-02-98013]
Место публикации : JETP Letters. - 2014. - Vol. 100, Is. 7. - P.455-462. - ISSN 0021-3640, DOI 10.1134/S0021364014190138. - ISSN 1090-6487
Примечания : Cited References: 28. - This work was supported by the Russian Foundation for Basic Research, project nos. 12-02-31130, 13-02-00523, and 13-02-98013.
Предметные рубрики: SINGLE-CHAIN MAGNETS
EASY-PLANE
ARRANGEMENT
MODEL
IONS
Аннотация: TThe excitation spectrum of a catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 anisotropic 1D magnet with alternating high-spin and low-spin iron ions has been calculated with the use of the diagrammatic technique for Hubbard operators. This has allowed establishing conformity with the Ising model, for which the magnetic susceptibility has been calculated by the transfer-matrix method. The introduction of a statistical ensemble taking into account the presence of chains with different lengths and iron ions with different spins has allowed describing the modification of the magnetic susceptibility under optical irradiation.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Goryainov S. V., Krylov A. S., Pan Y. M., Madyukov I. A., Smirnov M. B., Vtyurin A. N.
Заглавие : Raman investigation of hydrostatic and nonhydrostatic compressions of OH- and F-apophyllites up to 8 GPa
Место публикации : J. Raman Spectrosc.: WILEY-BLACKWELL, 2012. - Vol. 43, Is. 3. - P.439-447. - ISSN 0377-0486, DOI 10.1002/jrs.3049
Примечания : Cited References: 18. - This work was supported by the Siberian Division of RAS (Integration Project 109), the Russian Ministry of Science and Education and the CRDF (BRHE - REC-008 grant) and the Russian Foundation for Basic Research (RFBR-11-05-01121).
Предметные рубрики: RADIATION-INDUCED DEFECTS
ALPHA-QUARTZ
ROOM-TEMPERATURE
MEMORY GLASS
PRESSURE
FLUORAPOPHYLLITE
PHASE
MODEL
Ключевые слова (''Своб.индексиров.''): raman spectroscopy--high pressure--apophyllite--layer silicate--amorphization
Аннотация: Layer silicates F- and OH-apophyllites, KCa4Si8O20(F, OH)·8H2O, have been investigated by Raman spectroscopy at hydrostatic and nonhydrostatic pressures up to 8 GPa in diamond anvil cells using a 4 : 1 methanol–ethanol mix as pressure-transmitting medium. Our experiments show that at hydrostatic compression, apophyllites retain their crystalline states (i.e. no amorphization) up to 5 GPa. The wavenumbers of most bands exhibit linear dependences on pressure, except for a few ones, e.g. at 162 and 3565 cm–1 in OH-form (160.5 and 3558 cm–1 in F-form) that show nonlinear dependences. Nonhydrostatic compression with additional uniaxial loading induces amorphization of apophyllites. The majority of the bands in OH-apophyllite decreases markedly in intensity and shows considerable broadening under nonhydrostatic compression up to 3–6 GPa. In addition, the wavenumbers of several bands at nonhydrostatic compression exhibit considerable nonlinear dependences on pressure with strong hysteresis. These bands are mainly associated with vibrations of the interlayer ions and molecules and also of stretching and bending silicate sheets, hence being highly sensitive to the interlayer distance. Finally, we have calculated the lattice dynamics of F-apophyllite and interpreted the majority of bands, and these data are used to explain the complex baric behavior of the bands. Copyright © 2011 John Wiley & Sons, Ltd.
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