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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wigneron J. P., Chanzy A., Kerr Y. H., Lawrence H., Shi J. C., Escorihuela M. J., Mironov V. L., Mialon A., Demontoux F., de Rosnay P., Saleh-Contell K.
Заглавие : Evaluating an improved parameterization of the soil emission in L-MEB
Коллективы : Workshop on Remote Sensing and Modeling of Surface Properties (2nd; Jun 09-11, 2009; Toulouse, France)
Место публикации : IEEE Trans. Geosci. Remote Sensing: IEEE-Institute Electrical and Electronics Engineers, 2011. - Vol. 49, Is. 4. - P.1177-1189. - ISSN 0196-2892, DOI 10.1109/TGRS.2010.2075935
Примечания : Cited References: 26
Предметные рубрики: BAND MICROWAVE EMISSION
SURFACE-ROUGHNESS
1.4 GHZ
MODEL
MOISTURE
LAND
RADIOMETER
FREQUENCY
FIELDS
SPACE
Ключевые слова (''Своб.индексиров.''): microwave remote sensing--radiometry--roughness--soil moisture (sm)--soil moisture and ocean salinity (smos)--soil surface
Аннотация: In the forward model [L-band microwave emission of the biosphere (L-MEB)] used in the Soil Moisture and Ocean Salinity level-2 retrieval algorithm, modeling of the roughness effects is based on a simple semiempirical approach using three main "roughness" model parameters: H-R, Q(R), and N-R. In many studies, the two parameters Q(R) and N-R are set to zero. However, recent results in the literature showed that this is too approximate to accurately simulate the microwave emission of the rough soil surfaces at L-band. To investigate this, a reanalysis of the PORTOS-93 data set was carried out in this paper, considering a large range of roughness conditions. First, the results confirmed that Q(R) could be set to zero. Second, a refinement of the L-MEB soil model, considering values of N-R for both polarizations (namely, N-RV and N-RH), improved the model accuracy. Furthermore, simple calibrations relating the retrieved values of the roughness model parameters H-R and (N-RH - N-RV) to the standard deviation of the surface height were developed. This new calibration of L-MEB provided a good accuracy (better than 5 K) over a large range of soil roughness and moisture conditions of the PORTOS-93 data set. Conversely, the calibrations of the roughness effects based on the Choudhury approach, which is still widely used, provided unrealistic values of surface emissivities for medium or large roughness conditions.
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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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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Basis states and collective excitations of nonlocal three-spin polarons over the singlet phase of the CuO2 plane
Место публикации : JETP Letters. - 2012. - Vol. 95, Is. 4. - P.206-212. - ISSN 0021-3640, DOI 10.1134/S0021364012040091
Примечания : Cited References: 15. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Physics of Mesoscopic and Disordered Systems"), the Russian Foundation for Basic Research (project nos. 10-02-00251 and 11-02-98007-r-sibir'), and the Ministry of Education and Science of the Russian Federation (federal program "Human Capital for Science and Education in Innovative Russia" for 2009-2013).
Предметные рубрики: HEISENBERG-ANTIFERROMAGNET
SQUARE LATTICE
SPIN-POLARON
MODEL
Аннотация: An orthonormalized basis describing the single-hole states of the CuO2 plane has been constructed exactly taking into account the p-d exchange coupling between the spins of a hole and the two nearest copper ions. The introduced basis makes it possible to include the effects caused by the dependence of the Heisenberg interaction between the nearest copper ions on the occupation of the intermediate oxygen ion by the hole in the calculation of the spectrum of the collective excitations of nonlocal three-spin polarons. The inclusion of this correlation, as well as the nonlocality of the p-d exchange coupling, is the main difference of the developed approach to the description of the energy structure from the calculations with the use of the Zhang-Rice singlet.
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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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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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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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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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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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10.

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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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) : 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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pudlak M., Pichugin K. N., Nazmitdinov R. G., Pincak R.
Заглавие : Quantum nonequilibrium approach for fast electron transport in open systems: Photosynthetic reaction centers
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2011. - Vol. 84, Is. 5. - Ст.51912. - ISSN 1539-3755, DOI 10.1103/PhysRevE.84.051912
Примечания : Cited References: 34. - This work is partly supported by the Slovak Academy of Sciences in the framework of Center of Excellence NANOFLUID, VEGA Grants No. 2/0069/10, No. FIS2008-00781/FIS (Spain), and RFBR No. 11-02-00086 (Russia).
Предметные рубрики: BACTERIUM RHODOPSEUDOMONAS-VIRIDIS
PRIMARY CHARGE SEPARATION
AMINO-ACID-SEQUENCE
BACTERIOPHEOPHYTIN
RELAXATION
SUBUNIT
DONOR
MODEL
Ключевые слова (''Своб.индексиров.''): electron transfer--external fields--fast electron transport--initial conditions--non equilibrium--path-integral--perturbation theory--photosynthetic reaction center--second orders--time convolution--vibrational modes--electron transitions--perturbation techniques--quantum chemistry--photosynthesis
Аннотация: Creation of electrons or excitons by external fields in a system with initially statistically independent unrelaxed vibrational modes leads to an initial condition term. The contribution of this term in the time convolution generalized master-equation approach is studied in the second order of the perturbation theory in path-integral formalism. The developed approach, applied for the analysis of dynamics in the photosynthetic reaction center, exhibits the key role of the initial condition terms at the primary stage of electron transfer.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Golovnya A. A., Korovushkin M. M.
Заглавие : Kinematic mechanism of the modulation of the spectral intensity in the spatially uniform system of Hubbard fermions
Место публикации : JETP Letters. - 2011. - Vol. 94, Is. 3. - P.197-201. - ISSN 0021-3640, DOI 10.1134/S0021364011150148
Примечания : Cited References: 21. - We are grateful to R.O. Zaitsev and N.M. Plakida for the constructive criticism and helpful discussions. This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Physics of Condensed Matter"), the Russian Foundation for Basic Research (project no. 09-02-00127), the Ministry of Education and Science of the Russian Federation (federal program "Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013), and the Siberian Branch, the Russian Academy of Sciences (integration project no. 53). The work of A.A.G. and M.M.K. was also supported by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (grant no. MK-1300-2011.2) and by the Siberian Branch, Russian Academy of Sciences (Lavrent'ev Competition).
Предметные рубрики: SPIN SUSCEPTIBILITY
ANTIFERROMAGNETS
DYNAMICS
CHARGE
MODEL
Аннотация: Using the exact representation of the Green's function constructed in terms of the Hubbard operators, it has been shown that the kinematic interaction that induces the spin-fluctuation processes in the spatially uniform system of Hubbard fermions leads to significant variations in the spectral intensity A(k, omega) in the Brillouin zone. As a result, the modulation of A(k, omega) appears in the Fermi contour. The sign of the hopping integral within the first coordination sphere is determined by the contour section, where A(k, omega) decreases according to the angle-resolved photoemission spectroscopy data.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Electronic Structure of p-Type La1-xMx2+MnO3 Manganites in the Ferromagnetic and Paramagnetic Phases in the LDA plus GTB Approach
Разночтения заглавия :авие SCOPUS: Electronic structure of p-Type La 1-x M x 2+ MnO 3 manganites in the ferromagnetic and paramagnetic phases in the LDA + GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 5. - P860-876. - ISSN 1063-7761, DOI 10.1134/S1063776111030101
Примечания : Cited References: 47. - This study was supported financially by integration project no. 40 of the Ural and Siberian Branches of the Russian Academy of Sciences, the program "Strong Electron Correlations" of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 10-02-00251-a).
Предметные рубрики: DOUBLE-EXCHANGE
COLOSSAL MAGNETORESISTANCE
THIN-FILMS
PHYSICS
LA1-XSRXMNO3
RESISTIVITY
SEPARATION
TRANSPORT
MODEL
Ключевые слова (''Своб.индексиров.''): complex structure--cubic materials--ferromagnetic phase--half metals--jahn teller effect--metal properties--metal types--orbitals--p-type--paramagnetic phase--paramagnetic phasis--quasi particles--spectral intensity--spin projections--strong electron correlations--barium--density functional theory--electron correlations--electron density measurement--electronic properties--electronic structure--fermi level--ferromagnetic materials--ferromagnetism--manganese oxide--manganites--paramagnetic materials--paramagnetism--valence bands--lanthanum
Аннотация: The band structure, spectral intensity, and position of the Fermi level in doped p-type La1-xMx2+ MnO3 manganites (M = Sr, Ca, Ba) is analyzed using the LDA + GBT method for calculating the electronic structure of systems with strong electron correlations, taking into account antiferro-orbital ordering and using the Kugel-Khomskii ideas and real spin S = 2. The results of the ferromagnetic phase reproduce the state of a spin half-metal with 100% spin polarization at T = 0, when the spectrum is of the metal type for a quasiparticle with one spin projection and of the dielectric type for the other. It is found that the valence band becomes approximately three times narrower upon a transition to the paramagnetic phase. For the paramagnetic phase, metal properties are observed because the Fermi level is located in the valence band for any nonzero x. The dielectrization effect at the Curie temperature is possible and must be accompanied by filling of d(x) orbitals upon doping. The effect itself is associated with strong electron correlations, and a complex structure of the top of the valence band is due to the Jahn-Teller effect in cubic materials. DOI: 10.1134/S1063776111030101
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arbuzov A. B., Barbashov B. M., Nazmitdinov R. G., Pervushin V. N., Borowiec A., Pichugin K. N., Zakharov A. F.
Заглавие : Conformal Hamiltonian dynamics of general relativity
Место публикации : Phys. Lett. B: ELSEVIER SCIENCE BV, 2010. - Vol. 691, Is. 5. - P230-233. - ISSN 0370-2693, DOI 10.1016/j.physletb.2010.06.042
Примечания : Cited References: 30
Предметные рубрики: COSMOLOGICAL CONSTANT
UNIVERSE
GRAVITATION
SUPERNOVAE
MODEL
Ключевые слова (''Своб.индексиров.''): general relativity--cosmology--dilaton gravity--cosmology--dilaton gravity--general relativity
Аннотация: The General Relativity formulated with the aid of the spin connection coefficients is considered in the finite space geometry of similarity with the Dirac scalar dilaton. We show that the redshift evolution of the General Relativity describes the vacuum creation of the matter in the empty Universe at the electroweak epoch and the dilaton vacuum energy plays a role of the dark energy. (C) 2010 Elsevier B.V. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : The Interplay of Phonon and Magnetic Mechanism of Pairing in Strongly Correlated Electron System of High-T-c Cuprates
Коллективы :
Разночтения заглавия :авие SCOPUS: The interplay of phonon and magnetic mechanism of pairing in strongly correlated electron system of high-T c cuprates
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2010. - Vol. 23, Is. 5. - P733-736. - ISSN 1557-1939, DOI 10.1007/s10948-009-0633-z
Примечания : Cited References: 26. - This work is supported by the Presidium RAS program N 7 "Quantum physics of condensed matter," the integration project SORAN-UrORAN N 40, and the RFFI Grant 09-02-00127.
Предметные рубрики: PHASE-TRANSITIONS
OXIDE SUPERCONDUCTORS
SYMMETRY
COPPER
MODEL
BAND
BI2SR2CACU2O8+DELTA
LA2-XSRXCUO4
PB
Ключевые слова (''Своб.индексиров.''): high-t-c superconductivity--strong correlated electron systems--mechanisms of superconducting pairing--high-t c superconductivity--mechanisms of superconducting pairing--strong correlated electron systems--ab initio--buckling mode--correlated electron systems--critical temperatures--cuprates--fitting parameters--high-t--isotope effect--low energies--magnetic mechanisms--order of magnitude--phonon mode--strongly correlated electron system--strongly correlated electrons--superconducting pairing--superconductivity mechanism--type theory--buckling--copper compounds--electrons--isotopes--magnetic materials--phonons--superconductivity--superconducting magnets
Аннотация: We consider magnetic mechanism of superconducting pairing in the effective low energy t - t' - t '' - J* model with all parameters calculated ab initio. Interaction of strongly correlated electrons with different phonon modes is also incorporated. In a BCS type theory, the d(x2-y2) gap is given by a sum of magnetic and phonon contributions. The main contribution to the only fitting parameter G is determined by a competition of the breathing and buckling modes. Fitting the parameter G from the isotope effect, we obtain that magnetic and phonon contributions to the critical temperature T-c work together and are of the same order of magnitude.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Korovushkin M. M., Barabanov A. F.
Заглавие : Effective Interactions and the Nature of Cooper Instability of Spin Polarons in the 2D Kondo Lattice
Коллективы :
Разночтения заглавия :авие SCOPUS: Effective interactions and the nature of Cooper instability of spin polarons in the 2D Kondo lattice
Место публикации : JETP Letters. - 2008. - Vol. 88, Is. 6. - P.370-374. - ISSN 0021-3640, DOI 10.1134/S0021364008180069
Примечания : Cited References: 9. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Microphysics"), the Russian Foundation for Basic Research (project no. 06-02-16100), and the Siberian Branch, Russian Academy of Sciences (integration project no. 3.4). The work of M. M. Korovushkin was supported by the Krasnoyarsk Regional Science Foundation (project no. 18G).
Предметные рубрики: SUPERCONDUCTIVITY
ANTIFERROMAGNET
MODEL
Аннотация: It has been shown that two- and three-center interactions arise in the strong-coupling regime for the 2D Kondo lattice; these interactions both induce and suppress the Cooper instability. It is important that, in contrast to the t-J* model, the three- center interactions promote the Cooper pairing and ensure the appearance of the superconducting phase with a high critical temperature T(c). The calculated concentration dependences of T(c) agree well with the experimental data for the cuprate superconductors.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I.
Заглавие : Theory of magnetic excitations in iron-based layered superconductors
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2008. - Vol. 78, Is. 14. - Ст.140509. - ISSN 1098-0121, DOI 10.1103/PhysRevB.78.140509
Примечания : Cited References: 31
Предметные рубрики: NEUTRON-SCATTERING
INSTABILITY
STATE
ORDER
MODEL
Аннотация: Based on the effective four-band model we analyze the spin response in the normal and superconducting states of the Fe-pnictide superconductors. While the normal-state spin excitations are dominated by the continuum of the interorbital antiferromagnetic fluctuations and the intraband spin-density wave fluctuations, the unconventional superconductivity yields different feedback. The resonance peak in the form of the well-defined spin exciton occurs only for the interband scattering at the antiferromagnetic momentum Q(AFM) for the s(+/-) (extended s wave) superconducting order parameter and it disappears rapidly for q Q(AFM). The resonance feature is extremely weak for the d(x)(2)-y(2)-wave order parameter due to the specific Fermi-surface topology of these compounds. The essential difference between s(+/-)-wave and d(x)(2)-y(2)-wave symmetries for the magnetic excitations can be used for experimental determination of the superconducting wave-function symmetry.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Bound states in the continuum in photonic waveguides inspired by defects
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2008. - Vol. 78, Is. 7. - Ст.75105. - ISSN 1098-0121, DOI 10.1103/PhysRevB.78.075105
Примечания : Cited References: 53
Предметные рубрики: SCATTERING-THEORY
NUCLEAR REACTIONS
UNIFIED THEORY
TRANSMISSION
ELECTRON
MODEL
Аннотация: Photonic crystal with defect layer forms directed continuum for electromagnetic waves. Defect rods in the vicinity of the defect layer interact with the continuum and give rise to scattering of ingoing waves. We derive quantum-mechanical analog of the non-Hermitian Hamiltonian of the open system with complex eigenvalues, which describes a scattering of electromagnetic waves by the defect rods. In this formalism a bound state in the continuum (BIC) can be easily found by the condition that one of the complex eigenvalues becomes real for variation of dielectric constant of the defect rods. We numerically find BICs with discrete frequencies belong to the continuum for different arrangements of the defects and show that they are localized around the defects.
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