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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V., Zlotnikov A. O., Shustin M. S.
Заглавие : Majorana modes in BDI-class wire with strong Coulomb correlations [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1911.01035
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 55. - We acknowledge fruitful discussions with V.V. Valkov and V.A. Mitskan. The reported study was funded by the RAS Presidium programs for fundamental research Nos. 12 and 32, Russian Foundation for Basic Research (projects Nos. 18-32-00443, 19-02-00348), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects: ”The manifestation of Coulomb interactions and effects of bounded geometry in the properties of topological edge states of nanostructures with spin-orbit interaction” (No. 18-42-243017), ”Coulomb interactions in the problem of Majorana modes in low-dimensional systems with nontrivial topology” (No. 19-42-240011). S.A. and A.Z. are grateful to the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools, projects Nos. MK-3722.2018.2, MK-3594.2018.2.
Предметные рубрики: Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
Аннотация: In this study the problem of strong Coulomb interactions in topological superconducting wire is analyzed by means of the density-matrix-renormalization-group (DMRG) approach. To obtain the topological phase diagrams and analyze properties of edge states in the BDI-class structure the quantity called Majorana polarization is used. Its behavior agrees with the entanglement-spectrum degeneracy which has topological nature. The DMRG calculations for the Shubin-Vonsovsky-type model of the wire show the transformation of phases with Majorana single and double modes (MSMs and MDMs, respectively) under the increase of on- and inter-site correlations. In particular, the effects of MSM and MDM robustness as well as their induction are observed. It is shown that in the strongly correlated regime the contributions of single-particle excitations to the Majorana-type states significantly decrease if averaged on-site spin-dependent concentrations have comparable values. Moreover, the t−J∗−V-model is derived allowing to study the effective interactions and improve the DMRG numerics. In order to demonstrate the key role of spin and charge fluctuations in the revealed effects we analytically consider the limiting case of the effective Hamiltonian with infinitely strong on-site repulsion using the Hubbard-I approximation. Finally, the ways to probe the MSMs and MDMs via the features of caloric functions are discussed.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the 2D Heisenberg model with S=1/2
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 41, Is. 1. - P103-107. - ISSN 1063-7834, DOI 10.1134/1.1130737
Примечания : Cited References: 33
Предметные рубрики: SQUARE-LATTICE
GROUND-STATE
SPIN-CORRELATIONS
ANTIFERROMAGNET
LA2CUO4
EU2CUO4
ENERGY
ORDER
Аннотация: The two-dimensional (2D) Heisenberg model with anisotropic exchange (Delta=1-J(x)/J(z)) and S=1/2 is investigated by the quantum Monte Carlo method. The energy, susceptibility, specific heat, spin-spin correlation functions, and correlation radius are calculated. The sublattice magnetization (sigma) and the Neel temperature of the anisotropic antiferromagnet are logarithmic functions of the exchange anisotropy: 1/sigma + 1 + 0.13(1) ln(1/Delta). Crossover of the static magnetic structural factor as a function of temperature from power-law to exponential occurs for T(c)/J approximate to 0.4. The correlation radius can be approximated by 1/xi =2.05T(1.0(6))/exp(1.0(4)/ T). For La(2)CuO(4) the sublattice magnetization is calculated as sigma=0.45, the exchange is J=(1125=1305) K; for Er(2)CuO(4)J similar to 625 K and the exchange anisotropy Delta similar to 0.003. The temperature dependence of the static structural magnetic factor and the correlation radius above the Neel temperature in these compounds can be explained by the formation of topological excitations (spinons). (C) 1999 American Institute of Physics. [S1063-7834(99)02401-6].
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Effects of strong electron correlations in X-ray and electron spectra of high-T-c superconductors
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 5. - P788-809. - ISSN 1063-7834, DOI 10.1134/1.1131293
Примечания : Cited References: 92
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
COPPER-OXIDE SUPERCONDUCTORS
MULTIPLE-SCATTERING ANALYSIS
HIGH-ENERGY SPECTROSCOPY
ABSORPTION-SPECTRA
PHOTOELECTRON-SPECTRA
EDGE STRUCTURE
PHOTOEMISSION SPECTRA
INCOMPLETE SHELL
SINGLE-CRYSTAL
Аннотация: The current state of theoretical and experimental studies on the electronic structure of high-T-c superconductors is analyzed. The agreement between the theory and experimental spectroscopic data is shown to be rather poor in certain cases. The reason is that the X-ray and electronic spectra reveal strong electron correlations. At the same time, no realistic model has been developed up to now in which both one-electron and multielectron mechanisms of the formation of the spectra could be described in a unified way in compounds containing transition and rare-earth elements. In this paper, particular attention is paid to a sudden-perturbation model, by which it has been possible to describe or interpret some X-ray and electronic spectra, including both one-electron and multielectron effects. (C) 2000 MAIK "Nauka/Interperiodica".
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Effects of the intense electron correlations on the shape of x-ray CuK absorption spectra of La2-xSrxCuO4
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 108, Is. 4. - P.1479-1488. - ISSN 0044-4510
Примечания : Cited References: 28
Предметные рубрики: HIGH-TC SUPERCONDUCTIVITY
EDGE STRUCTURE
LA2CUO4
SATELLITES
ALPHA
EXCITATIONS
COPPER
OXIDES
STATE
SHAKE
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Influence of strong electron correlations on the form of the x-ray Cu K absorption spectra of La2-xSrxCuO4
Место публикации : J. Exp. Theor. Phys. - 2011. - Vol. 81, Is. 4. - P.811-816. - ISSN 1063-7761
Примечания : Cited References: 24. - We thank the Scientific Council for the Problem of HighTemperature Superconductivity for support under Project
Аннотация: The influence of strong electron correlations on the x-ray Cu K absorption spectra has been investigated using the extended p-d model and the sudden approximation. The structure of the vacant above-threshold single-electron Cu p states has been modeled by the SCF X, scattered wave method. It has been shown that the Cu K spectrum is determined by a convolution of the spectra of single-electron absorption by vacant orbitals below and above the ionization threshold and of many-electron transitions within the system of valence electrons. This makes it possible to attribute the main peak of the Cu K spectrum of La2Cu04 to the Cu dlOL configuration and the single high-energy satellite to the Cu d9 configuration. The LaSrCu04 spectrum has been calculated with allowance for both singlet and triplet two-hole states of the CuO, cell. Comparison with experimental data reveals that the main two-hole state is a triplet, which also forms the absorption spectrum consisting of the main maximum corresponding to the Cu ~'OLL configuration and two satellites corresponding to the Cu d9L and Cu d8 configurations. All the theoretical spectra obtained agree well with the experimental data. O 1995 American Institute of Physics.
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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Bolyachkin A. S., Dengina E., Komogortsev S. V.
Заглавие : Magnetic Correlations and Coercivity in Nanocrystalline Alloys With Grain-Size Distribution.
Коллективы : Annual conference on мagnetism and мagnetic мaterials
Место публикации : 65th Annual conference on мagnetism and мagnetic мaterials (MMM-2020): abstract book. - 2020. - Ст.R5-01. - P.564
Примечания : Cited References: 1
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Borisov A.A., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Temperature and concentration dependences of the electronic structure of copper oxides in the generalized tight binding method
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 4. - P773-780. - ISSN 1063-7761, DOI 10.1134/1.1625067
Примечания : Cited References: 25
Предметные рубрики: SUPERCONDUCTING-GAP ANISOTROPY
BAND-STRUCTURE
FERMI-SURFACE
NORMAL-STATE
BI2SR2CACU2O8+DELTA
EVOLUTION
Ключевые слова (''Своб.индексиров.''): doping (additives)--electron transitions--electronic structure--fermi level--fermi surface--electron correlations--pseudogap--tight binding method--valence band--copper oxides
Аннотация: The electronic structure of p-type doped HTSC cuprates is calculated by explicitly taking into account strong electron correlations. The smooth evolution of the electronic structure from undoped antiferromagnetic to optimally and heavily doped paramagnetic compositions is traced. For a low doping level, in-gap impurity-type states are obtained, at which the Fermi level is pinned in the low-doping region. These states are separated by a pseudogap from the valence band. The Fermi surfaces calculated for the paramagnetic phase for various concentrations of holes are in good agreement with the results of ARPES experiments and indicate a gradual change in the Fermi surface from the hole type to the electron type. (C) 2003 MAIK "Nauka/Interperiodica".
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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Thakur A., Edelman I. S., Ovchinnikov S. G., Sukhachev A. L., Petrov D. A., Thakur P.
Заглавие : Co-Zn nanoferrites for high frequency applications: correlations between dielectric and magnetic properties
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 1, Sect.: Spintronics and magnetic nanostructures. - Ст.A.O5. - P.37-38. - ISBN 978-5-94469-051-7
Примечания : Cited References: 2
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Usmanov O. V., Ovsianikov A. K., Zobkalo I. A., Shaykhutdinov K. A., Terentjev K. Yu., Semenov S. V.
Заглавие : Crystal field parameters and magnetic properties correlations in rare-earth orthoferrite HoFeO3
Место публикации : J. Surf. Invest. - 2022. - Vol. 16, Is. 6. - P.1041-1047. - ISSN 10274510 (ISSN), DOI 10.1134/S1027451022060258. - ISSN 18197094 (eISSN)
Примечания : Cited References: 28. - This work was supported by the Russian Foundation for Basic Research grant no. 19-52-12 047, and DFG grant no. SA 3688/1-1
Аннотация: The crystal structure and magnetic properties investigations of holmium orthoferrite compound HoFeO3 were performed in temperature range 7–300 K. Obtained XRD data confirm that HoFeO3 retains the orthorhombic perovskite structure of Pbnm space group. The crystal electric field (CEF) parameters of Ho3+ ion subsystem has been revealed numerically on the base of point charge model in the same temperature range. By this set of parameters CEF the splitting of Ho3+ energy levels was calculated and their temperature evolution was obtained. Modelling of isothermal magnetization M(H) with obtained set of parameters was carried out. Ho3+ single ion anisotropy due to CEF effects was demonstrated. Bulk magnetization evaluated from CEF was compared to experimental data.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G., Shneyder E. I.
Заглавие : Dependence of the critical temperature of high-temperature superconductors on the hoppings and spin correlations between Cu02-planes
Коллективы : "Strongly Correlated Electronic Systems", Conf.
Место публикации : Strongly Correlated Electronic Systems 2011 (SCES 2011): Proceeding. - 2011
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Korovushkin M. M., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Diagram Approach to the Problem of the Normal Phase Properties of the Spin-Polaron Ensemble in Cuprate Superconductors
Место публикации : J. Low Temp. Phys. - 2019. - Vol. 197, Is. 1-2. - P.34-43. - ISSN 00222291 (ISSN), DOI 10.1007/s10909-019-02211-9
Примечания : Cited References: 29. - The work was supported by the program of the Presidium of the Russian Academy of Sciences No. 12 “Fundamental problems of high-temperature superconductivity,” the Russian Foundation for Basic Research (RFBR) (Projects Nos. 18-02-00837 and 19-02-00509) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (Projects Nos. 18-42-243002 “Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors,” 18-42-243018 “Contact phenomena and magnetic disorder in the problem of the formation and detection of topological edge states in semiconductor nanostructures,” and 18-42-240014 “Single-orbit effective model of an ensemble of spin-polaron quasiparticles in the problem of describing the intermediate state and pseudogap behavior of cuprate superconductors”).
Аннотация: Taking into account the real crystalline structure of the CuO 2 plane within the spin-fermion model and using the diagram technique, the spin-polaron concept of the fermionic excitations in cuprate superconductors is implemented. It is shown that an account of the on-site scattering processes leads to considerable binding energy of the spin-polaron quasiparticles. An account of the two-site spin-fermion scattering processes results in the energy spectrum and spectral properties of the spin-polaron quasiparticles which agree well with experimental data on cuprate superconductors.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Kokorina E. E., Pchelkina Z. V.
Заглавие : Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: the LDA + GTB approach
Разночтения заглавия :авие SCOPUS: Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: The LDA+GTB approach
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2007. - Vol. 19, Is. 48. - Ст.486203. - ISSN 0953-8984, DOI 10.1088/0953-8984/19/48/486203
Примечания : Cited References: 36
Предметные рубрики: NARROW ENERGY BANDS
HUBBARD-MODEL
SUPERCONDUCTORS
DENSITY
TEMPERATURE
ORBITALS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--band structure--correlation methods--crystal structure--local density approximation--superconducting materials--electronic correlations--fermionic quasiparticles--neodymium compounds
Аннотация: In the present work we report band structure calculations for the high-temperature superconductor Nd2-xCexCuO4 in the regime of strong electronic correlations within an LDA + GTB method, which combines the local density approximation (LDA) and the generalized tight-binding method (GTB). The two mechanisms of band structure doping dependence were taken into account. Namely, the one-electron mechanism provided by the doping dependence of the crystal structure, and the many-body mechanism provided by the strong renormalization of the fermionic quasiparticles due to the large on-site Coulomb repulsion. We have shown that, in the antiferromagnetic and in the strongly correlated paramagnetic phases of the underdoped cuprates, the main contribution to the doping evolution of the band structure and Fermi surface comes from the many-body mechanism.
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13.

Вид документа : Статья из журнала (Препринт)
Шифр издания :
Автор(ы) : Kuz'min V. I., Visotin M. A., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Doping and temperature evolution of pseudogap and spin-spin correlations in the two-dimensional Hubbard model [Electronic resource]
Место публикации : ArXiv. - 2020. - Ст.2001.05143
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 86. - The reported study was funded by RFBR according to the research project No. 18-32-00256 (all the results concerning the influence of short-range correlations on the electronic spectral properties). The reported study was also funded by Russian Foundation for Basic Research and 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” number 19-42-240007, and “Features of electron-phonon coupling in high-temperature superconductors with strong electron correlations” number 18-42-240017
Предметные рубрики: Strongly Correlated Electrons
Аннотация: Cluster perturbation theory is applied to the two-dimensional Hubbard t−t′−t′′−U model to obtain doping and temperature dependent electronic spectral function with 4×4 and 12-site clusters. It is shown that evolution of the pseudogap and electronic dispersion with doping and temperature is similar and in both cases it is significantly influenced by spin-spin short-range correlations. When short-range magnetic order is weakened by doping or temperature and Hubbard-I like electronic dispersion becomes more pronounced, the Fermi arc turns into large Fermi surface and the pseudogap closes. It is demonstrated how static spin correlations impact the overall dispersion's shape and how accounting for dynamic contributions leads to momentum-dependent spectral weight at the Fermi surface and broadening effects.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Visotin M. A., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Doping and temperature evolution of pseudogap and spin-spin correlations in the two-dimensional Hubbard model
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [18-32-00256, 18-32-01062]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science [19-42-240007, 18-42-240017]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 11. - Ст.115141. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.115141. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 97. - The reported study was funded by RFBR according to Research Project No. 18-32-00256 (all the results concerning the influence of short-range correlations on the electronic spectral properties). The reported study was also funded by RFBR according to Research Project No. 18-32-01062; the Russian Foundation for Basic Research and Government of Krasnoyarsk Territory, the Krasnoyarsk Regional Fund of Science to the Research Projects "Electronic correlation effects and multiorbital physics in iron-based materials and cuprates" No. 19-42-240007 and "Features of electron-phonon coupling in high-temperature superconductors with strong electron correlations" No. 18-42-240017.
Предметные рубрики: QUASI-PARTICLE DISPERSION
FERMI-SURFACE
QUANTUM OSCILLATIONS
LANCZOS METHOD
Аннотация: Cluster perturbation theory is applied to the two-dimensional Hubbard t - t' - t '' - U model to obtain doping and temperature-dependent electronic spectral function with 4 x 4 and 12-site clusters. It is shown that evolution of the pseudogap and electronic dispersion with doping and temperature is similar and in both cases it is significantly influenced by spin-spin short-range correlations. When short-range magnetic order is weakened by doping or temperature and Hubbard-I-like electronic dispersion becomes more pronounced, the Fermi arc turns into a large Fermi surface and the pseudogap closes. It is demonstrated how static spin correlations impact the overall dispersion's shape and how accounting for dynamic contributions leads to momentum-dependent spectral weight at the Fermi surface and broadening effects.
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15.

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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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Gavrichkov V. A., Shneyder E. I., Nekrasov I. A., Slobodchikov A. A., Ovchinnikov S. G., Bianconi A.
Заглавие : Effect of CuO2 lattice strain on the electronic structure and properties of high-Tc cuprate family
Место публикации : J. Supercond. Novel Magn. - 2019. - Vol. 32, Is. 7. - P.1927-1935. - ISSN 15571939 (ISSN) , DOI 10.1007/s10948-018-4936-9
Примечания : Cited References: 51. - We thank the Presidium RAS program No.12 “Fundamental problems of high temperature superconductivity” for the financial support under the project 0356-2018-0063. The reported study was funded by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science according to the research project:“Features of electron-phonon coupling in high-temperature superconductors with strong electronic correlations” No. 18-42-240017. This work was done under the State contract (FASO) No. 0389-2014-0001 and supported in part by RFBR grants No. 17-02-00015 and 18-02-00281.
Аннотация: Doping and strain dependences of the electronic structure of the CuO6-octahedra layer within LDA+GTB method in the frameworks of six-band p-d model are calculated. Band structure and Fermi surface of the quasiparticle excitations in the effective Hubbard model are characterized by inhomogeneous distribution of the k-dependent spectral weight. Doping results in reconstruction of the band structure, redistribution of the spectral weight over dispersion surface, and reconstruction of Fermi surface from small hole pockets in the underdoped region to large hole contour in the overdoped region through two quantum phase transitions (QPT). Strain increasing leads to displacement of the valence and conductivity bands, bandwidths decreasing, and shift of the concentrations corresponding to QPTs. Strain dependences of the antiferromagnetic exchange coupling and DOS at the Fermi level determining superconducting temperature Tc are obtained. Effective exchange coupling in the equation for Tc demonstrates monotonic strain dependence.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Tarasov I. A., Varnakov S. N., Yakovlev I. A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Effect of electron correlations on the Fe3Si and α- FeSi2 band structure and optical properties
Коллективы : Russian Fund of Basic Research [14002-00186, 13-02-01265]; President of Russia Grants [2886.2014.2, 924.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 20. - Ст.205129. - ISSN 1098-0121, DOI 10.1103/PhysRevB.92.205129. - ISSN 1550-235X(eISSN)
Примечания : Cited References:69. - The theoretical part of this work was supported by Russian Fund of Basic Research, Grant No. 14002-00186 and the President of Russia Grants No. 2886.2014.2 and No. 924.2014.2 for support of Leading Scientific School. The calculations were performed with the computer resources of NRC "Kurchatov Institute" (ui2.computing.kiae.ru). The experimental work was supported by Russian Fund of Basic Research, Grant No. 13-02-01265. I.S. thanks A. Ruban for useful discussion.
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
AUGMENTED-WAVE METHOD
BASIS-SET
METALS
ABSORPTION
EMISSION
SURFACES
ALLOYS
LAYERS
Аннотация: We use the Vienna ab initio simulation package (vasp) for evaluation of the quasiparticle spectra and their spectral weights within Hedin's GW approximation (GWA) for Fe3Si and α-FeSi2 within the non-self-consistent one-shot approximation G0W0 and self-consistent scGWA with the vertex corrections in the particle-hole channel, taken in the form of two-point kernel. As input for G0W0, the band structure and wave functions evaluated within the generalized gradient corrected local-density approximation to density functional theory (GGA) have been used. The spectral weights of quasiparticles in these compounds deviate from unity everywhere and show nonmonotonic behavior in those parts of bands where the delocalized states contribute to their formation. The G0W0 and scGWA spectral weights are the same within 2%–5%. The scGWA shows a general tendency to return G0W0 bands to their GGA positions for the delocalized states, while in the flat bands it flattens even more. Variable angle spectroscopic ellipsometry measurements at T=296 K on grown single-crystalline ∼50-nm-thick films of Fe3Si on n-Si(111) wafer have been performed in the interval of energies ω∼(1.3–5) eV. The comparison of G0W0 and scGW theory with experimental real and imaginary parts of permittivity, refractive index, extinction and absorption coefficients, reflectivity, and electron energy loss function shows that both G0W0 and scGW qualitatively describe experiment correctly, the position of the low-energy peaks is described better by the scGW theory, however, its detailed structure is not observed in the experimental curves. We suggest that the angle-resolved photoemission spectroscopy experiments, which can reveal the fine details of the quasiparticle band structure and spectral weights, could help to understand (i) if the scGWA with this type of vertex correction is sufficiently good for description of these iron silicides and, possibly, (ii) why some features of calculated permittivity are not seen in optical experiments.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Antipina L. Yu., Tomilin F. N., Kuzubov A. A.
Заглавие : Effect of electron correlations on the structure of photoprotein substrates
Коллективы :
Место публикации : JETP Letters. - 2010. - Vol. 91, Is. 9. - P.490-493. - ISSN 0021-3640, DOI 10.1134/S0021364010090122
Примечания : Cited References: 14. - This work was supported by the Russian Foundation for Basic Research (project no. 07-04-00930-a), by the Presidium of the Russian Academy of Sciences (program "Molecular and Cellular Biology"), and by the Siberian Branch, Russian Academy of Sciences (project no. 2).
Предметные рубрики: ANGSTROM RESOLUTION
CRYSTAL-STRUCTURE
AEQUORIN
ENERGY
OBELIN
GAS
Аннотация: The electronic structure and total energy of various isomeric forms of coelenterazine and coelenteramide have been calculated by quantum chemistry methods both in the single-electron approximation and taking into account correlation effects. It has been shown that the inclusion of electron correlations makes it possible to obtain the structure of the coelenteramide close to the experimentally determined structure, as well as to choose the structure of the coelenterazine CLZ(1H) as the most probable isomeric form.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Shneyder E. I.
Заглавие : Effect of short antiferromagnetic correlations on the normal and superconducting properties in copper oxides
Место публикации : Diffusion and Defect Data Pt.B: Solid State Phenomena: Trans Tech Publications Ltd, 2011. - Vol. 168-169. - С. 561-566. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.561
Ключевые слова (''Своб.индексиров.''): high temperature superconductivity--short range antiferromagnetic order--strong electron correlations--antiferromagnetic materials--antiferromagnetism--copper oxides--electron correlations--electron density measurement--antiferromagnetism--electron correlations--ab initio--antiferromagnetic correlations--cuprates--high-t--high-temperature superconductivity--hubbard--low energies--multiband model--short range antiferromagnetic order--strong electron correlations--superconducting properties--t-j models--antiferromagnetic orderings--superconductivity--copper oxides--high temperature superconductivity
Аннотация: The abnormal "normal" state and origin of high temperature superconductivity in cuprates are still not clear [1-2]. The strong electron correlations (SEC) are known to be one of the main difficulties for the theory of high- Tc cuprates. The conventional LDA (local density approximation) approach to the band structure fails in the regime of SEC. Various realistic multiband models of a CuO2 layer at low energy result in the effective Hubbard or t - J models [3-7]. The hybrid LDA+GTB scheme [8] generates the low-energy effective t - t? - t? - J* model with all parameters calculated ab initio.
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20.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S.G., Korshunov M.M., Shneyder E.I.
Заглавие : Effect of short order antiferromagnetic correlations on the normal and superconducting properties in copper oxides
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Уральское отделение РАН
Место публикации : IV Euro-Asian Symposium "Trends in MAGnetism" Nanospintronics (EASTMAG-2010). School for young scientist "Spintronics": June 28 - Lule 2, 2010"Book of abstracts. - Ekaterinburg, 2010. - P.60
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