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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zakharov Yu. V., Mankov Yu. I., Titov L. S.
Заглавие : Anisotropy of the magnetoresistance along and across domain-walls in a ferromagnet
Место публикации : J. Phys. I. - 1991. - Vol. 1, Is. 5. - P.759-764. - ISSN 1155-4304
Примечания : Cited References: 20
Предметные рубрики: SUPERCONDUCTIVITY
HOMO6S8
Аннотация: We discuss some peculiarities of the conduction electron motion in the vicinity of domain walls which lead to an anisotropy of the magnetoresistance. We also discuss the case of single crystals of ErRh4B4 and HoMo6S8 where magnetoresistance with the same qualitative features has been observed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Valkova T. A.
Заглавие : Anomalies in the quantum excitation spectrum of a magnetic material with a strong quasi-particle interaction
Место публикации : JETP Letters. - 1990. - Vol. 52, Is. 11. - P.589-592. - ISSN 0021-3640
Примечания : Cited References: 6
Предметные рубрики: SUPERCONDUCTIVITY
Аннотация: It is shown in a nonlinear theory that the quantum spectrum of excitations becomes analogous to the spectrum of excitations of a quantum Bose liquid in the case of a highly anisotropic ferromagnet, with a large number of interacting quasiparticles.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : Manifestation of spin-charge fluctuations in the spectral and thermodynamic properties of quasi-two-dimensional rare-earth intermetallic compounds
Коллективы : RFBR [16-02-00073-a, 15-42-04372-r-Siberia-a]; Government of the Krasnoyarsk Region; Regional Science Foundation [07/16]; Integrated program II.2P of SB RAS [0358-2015-0002]; Presidential scholarships for young PhDs [SP-1370.2015.5]
Место публикации : Low Temp. Phys.: American Institute of Physics, 2017. - Vol. 43, Is. 2. - P.191-199. - ISSN 1063-777X, DOI 10.1063/1.4977211. - ISSN 1090-6517(eISSN)
Примечания : Cited References:35. - This work was supported by RFBR (Grants Nos. 16-02-00073-a and 15-42-04372-r-Siberia-a), the Government of the Krasnoyarsk Region and the Regional Science Foundation (Ext. Agreement No. 07/16), as well as the Integrated program II.2P of SB RAS (Project No. 0358-2015-0002). One of the authors (A.O.Z.) acknowledges the support by the Presidential scholarships for young PhDs (SP-1370.2015.5).
Предметные рубрики: PERIODIC ANDERSON MODEL
INTERMEDIATE-VALENCE COMPOUNDS
MAGNETIC PHASE-DIAGRAM
HEAVY
SUSCEPTIBILITY
APPROXIMATION
ANTIFERROMAGNETISM
SUPERCONDUCTIVITY
LATTICE
METALS
Аннотация: In the framework of the modified periodic Anderson model with exchange interaction in the subsystem of localized states, it is shown that spin-charge fluctuations in quasi-two-dimensional intermetallic compounds with rare-earth ions in the mixed valence state significantly affect both the spectrum of magnetic excitations and the conditions at which the antiferromagnetic phase is realized. The spectral characteristics of the phase were obtained by the method of the diagram technique for Hubbard operators in the one-loop approximation, which allows to account for the spincharge fluctuation contributions to the components of the mass and the force operators. The developed theory allowed to quantitatively describe the pressure dependence of the Neel temperature observed in a quasi-two-dimensional antiferromagnetic heavy-fermion intermetallic compound CeRhIn5. Published by AIP Publishing.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Dynamical magnetic susceptibility of the periodic anderson model in the chaotic phase approximation
Коллективы :
Место публикации : Theor. Math. Phys.: SPRINGER, 2010. - Vol. 164, Is. 2. - P.1089-1099. - ISSN 0040-5779, DOI 10.1007/s11232-010-0087-2
Примечания : Cited References: 17. - This work was supported in part by the the Presidium of the Russian Academy of Sciences (Program "Quantum Physics of Condensed Matter"), the Siberian Branch of the Russian Academy of Sciences (Interdisciplinary Integration Project No. 53), by the Federal Target Program ("Scientific and Scientific-Pedagogical Resources of Innovated Russia in Years 2009-2013"), and the Russian Foundation for Basic Research (Grant No. 10-02-00251).
Предметные рубрики: CORRELATED ELECTRON-SYSTEMS
HUBBARD OPERATORS
SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): periodic anderson model--generalized chaotic phase approximation--dynamical magnetic susceptibility
Аннотация: Using the diagram technique in the atomic representation in the generalized chaotic phase approximation, we solve the problem of calculating the dynamical magnetic susceptibility of the periodic Anderson model in the strong electron correlation regime. We express the dynamical magnetic susceptibility in terms of four Matsubara Green's functions describing partial contributions, which are calculated based on exact solutions of integral equations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : d-Wave pairing in an ensemble of spin polaron quasiparticles in the spin-fermion model of the electronic structure of the CuO2 plane
Коллективы : Dynasty Foundation, Russian Foundation for Basic Research (Siberia) [13-02-00523,13-02-00909, 13-02-98013]
Место публикации : Phys. Lett. A: Elsevier Science, 2015. - Vol. 379, Is. 5. - P.421-426. - ISSN 0375, DOI 10.1016/j.physleta.2014.11.036. - ISSN 18732429(eISSN)
Примечания : Cited References:26. - This study was supported by the Russian Foundation for Basic Research,projects Nos. 13-02-00523, 13-02-00909 and 13-02-98013 (Siberia) and theDynasty Foundation.
Предметные рубрики: SUPERCONDUCTIVITY
ANTIFERROMAGNETISM
Ключевые слова (''Своб.индексиров.''): hight-temperature cuprate superconductors--tree-band p-d model--spin--polaron--strong electron correlations
Аннотация: It is demonstrated for the first time that the strong coupling between spin moments of copper ions and oxygen holes, which arises upon hybridization mixing of two hole subsystems in the Emery model, not only affects the formation of spin polaron quasiparticles but also ensures effective attraction between them via the exchange interaction. This results in the Cooper instability with d-wave pairing in a 2D ensemble of spin polaron quasiparticles. The T-x phase diagram obtained using this approach agrees well with the available experimental data. (C) 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Shneyder E. I., Kozlov P. A., Ovchinnikov S. G.
Заглавие : Transition between large and small polaron states in the electronic structure of HTSC cuprates
Коллективы : RFBR [13-02-01395 a, 14-02-31677 mol_a]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1063-1068. - ISSN 1557-1939, DOI 10.1007/s10948-016-3375-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:10. - This work was funded by RFBR according to the research projects No. 13-02-01395 a and No. 14-02-31677 mol_a.
Предметные рубрики: SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): cuprates--strong electron correlations--electron-phonon interaction--polaron--franck-condon process--hubbard fermions--band structure
Аннотация: The effect of strong electron correlations (SEC) and strong electron-phonon interaction (EPI) on the electronic structure of cuprates is studied within the polaronic version of the generalized tight binding method. Both diagonal and off-diagonal EPI in terms of ionic coordinates are considered.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Li, Oksana A., Lin, Chun-Rong, Chen, Hung-Yi, Hsu, Hua-Shu, Wu, Kai-Wun, Tseng, Yaw-Teng, Bayukov O. A., Edelman I. S., Ovchinnikov S. G., Shih, Kun-Yauh
Заглавие : Structural and magnetic properties of Fe1−xCoxSe1.09 nanoparticles obtained by thermal decomposition
Место публикации : Mater. Res. Express: IOP Publishing, 2015. - Vol. 2, No. 12. - Ст.126501. - ISSN 2053-1591, DOI 10.1088/2053-1591/2/12/126501
Примечания : Cited References: 30. - This work is supported by the Ministry of Science and Technology of Taiwan (MOST103-2811-M-153 -001 and MOST102-2112-M-153 -002 -MY3).
Предметные рубрики: X-RAY-DIFFRACTION
MOSSBAUER-SPECTROSCOPY
CRYSTAL-STRUCTURES
IRON SELENIDES
SUPERCONDUCTIVITY
FeSe
MARCASITE
PYRITE
Ключевые слова (''Своб.индексиров.''): nanoparticles--chalcogenide--iron-cobalt selenide--ferrimagnetism--paramagnetism--mossbauer spectroscopy
Аннотация: A series of Fe1−xCoxSe1.09 (x = 0 to ) nanoparticles were synthesized by thermal decomposition method. Particles in composition range Fe0.5Co0.5Se1.09 to CoSe1.09 crystallized in monoclinic structure of Co6.8Se8 , while FeSe1.09 crystallized in hexagonal structure of FeSe achavalite. Magnetization dependences on temperature and external magnetic field reveal complicated magnetic behavior and correspond to the sum of paramagnetic and superparamagnetic response. Mössbauer spectra contain several paramagnetic doublets with parameters corresponding to nonequivalent positions of divalent and trivalent iron cations with low spin. The nonequivalent positions appeared due to inhomogeneous distribution of Co ions or metal vacancies in iron surrounding.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Janowitz C., Seidel U., Unger RST, Krapf A., Manzke R., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta
Разночтения заглавия :авие SCOPUS: Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xY xCu2O8+δ
Место публикации : JETP Letters. - 2004. - Vol. 80, Is. 11. - P.692-696. - ISSN 0021-3640, DOI 10.1134/1.1862796
Примечания : Cited References: 18
Предметные рубрики: ELECTRONIC-STRUCTURE
APICAL OXYGEN
MODEL
SUPERCONDUCTIVITY
ONSET
Аннотация: The experimental dispersion of the first removal state in the insulating Bi2Sr2Ca1 - xYxCu2O8 + delta regime is found to differ significantly from that of other parent materials: oxyclorides and La2CuO4. For Y contents of 0.92 greater than or equal to x greater than or equal to 0.55 due to nonstoichiometric effects in the Bi-O layers, the hole concentration in the CuO2 layers is almost constant and, on the contrary, the crystal lattice parameters a, b, c change very strongly. This (a, b) parameter increase and c parameter decrease results in an unconventional three peak structure at (0, 0), (pi/2, pi/2), (pi, pi) for x = 0.92. We can describe the experimental data only beyond the framework of the three-band p-d-model involving the representations of a new triplet counterpart for the Zhang-Rice singlet state. (C) 2004 MAIK "Nauka/Interperiodica".
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Richter M.
Заглавие : Local gauge invariance versus slave boson-like representations in systems with strongly correlated electrons
Место публикации : Phys. Scr.: ROYAL SWEDISH ACAD SCIENCES, 1996. - Vol. 54, Is. 4. - P410-416. - ISSN 0281-1847, DOI 10.1088/0031-8949/54/4/020
Примечания : Cited References: 38
Предметные рубрики: T-J MODEL
VALENCE-BOND STATE
DIAGRAM TECHNIQUE
ANDERSON MODEL
HUBBARD MODEL
SUPERCONDUCTIVITY
LIMIT
PHASE
Аннотация: The flux phase solutions in the t-J model the gauge theories with Chern-Simons term, promising new exciting physics, are so far obtained only within slave-boson (or fermion) approaches, where local gauge invariance is not taken into account exactly. We inspect the possibility to do this, mainly, in the example of the t-J model The analysis of different parametrizations in the functional representation shows that (i) calculations which take into account constraints for the number of on-site-available states are describing quasiparticles in terms of the wrong local statistics, and contain gauge non-invariant objects; (ii) application of the projection technique in the slave-boson(fermion) representation reproduces the correct statistics, and is exactly equivalent to the conventional diagram technique for Hubbard operators. In the language of slave bosons this means that the Fourier transformation leading to Bloch states should be made only after accounting constraints in the measure of functional integral.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shtarev, Dmitry S., Shtareva, Anna, V, Kevorkyants, Ruslan, Molokeev M. S., Serpone, Nick
Заглавие : Revisiting the BaBiO3 semiconductor photocatalyst: synthesis, characterization, electronic structure, and photocatalytic activity
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [19-73-10013]
Место публикации : Photochem. Photobiol. Sci. - 2021. - Vol. 20, Is. 9. - P.1147-1160. - ISSN 1474-905X, DOI 10.1007/s43630-021-00086-y. - ISSN 1474-9092(eISSN)
Примечания : Cited References: 48. - We wish to thank the Russian Science Foundation for a Grant (Project No. 19-73-10013) in support of our study. The authors are also grateful to the staff of the following Institutes/Centers for their valuable technical assistance and in providing the needed equipment: (i) the Khabarovsk Innovation and Analytical Center of the Yu. A. Kosygin Institute of Tectonics and Geophysics FEB RAS; and (ii) the Resource Centers of the Research Park at Saint-Petersburg State University, especially the Center for Physical Methods of Surface Investigation and the Nanophotonics Center. One of us (NS) is grateful to the staff of the PhotoGreen Laboratory of the University of Pavia, Italy, for their continued hospitality
Предметные рубрики: RHODAMINE-B
OXIDE
DRIVEN
SUPERCONDUCTIVITY
PSEUDOPOTENTIALS
Аннотация: This article revisits the properties of BaBiO3 examined extensively in the last two decades because of its electronic properties as a superconductor and as a semiconductor photocatalyst. Solid-state syntheses of this bismuthate have often involved BaCO3 as the barium source, which may lead to the formation of BaBiO3/BaCO3 heterostructures that could have an impact on the electronic properties and, more importantly, on the photocatalytic activity of this bismuthate. Accordingly, we synthesized BaBiO3 by a solid-state route to avoid the use of a carbonate; it was characterized by XRD, SEM, and EDX, while elemental mapping characterized the composition and the morphology of the crystalline BaBiO3 and its thin films with respect to structure, optoelectronic, and photocatalytic properties. XPS, periodic DFT calculations, and electrochemical impedance spectroscopy ascertained the electronic and electrical properties, while Raman and DRS spectroscopies assessed the relevant optical properties. The photocatalytic activity was determined via the degradation of phenol in aqueous media. Although some results accorded with earlier studies, the newer electronic structural data on this bismuthate, together with the photocatalytic experiments carried out in the presence of selective radical trapping agents, led to elucidating some of the mechanistic details of the photocatalytic processes that previous views of the BaBiO3 band structure failed to address or clarify. Analytical refinement of the XRD data inferred the as-synthesized BaBiO3 adopted the C2/m symmetry rather than the I2/m structure reported earlier, while Tauc plots from DRS spectra yielded a bandgap of 2.05 eV versus the range of 1.1–2.25 eV reported by others; the corresponding flatband potentials were 1.61 eV (EVB) and − 0.44 eV (ECB). The photocatalytic activity of BaBiO3 was somewhat greater than that of the well-known Evonik P25 TiO2 photocatalyst under comparable experimental conditions.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : OVCHINNIKOV S. G.
Заглавие : EFFECT OF SUBSTITUTIONAL IMPURITY SPECIES ON THE SUPPRESSION OF MAGNETIC-PROPERTIES OF WEAKLY DOPED COPPER OXIDES
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 5. - P1307-1310. - ISSN 0367-3294
Примечания : Cited References: 16
Предметные рубрики: ELECTRONIC-STRUCTURE
SUPERCONDUCTIVITY
LA2CUO4
EXCITATIONS
SPECTRA
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Density of hole-doped states in strongly correlated electron-systems of copper oxides
Разночтения заглавия :авие SCOPUS: Density of hole-doped states in strongly correlated electron systems of copper oxides
Место публикации : Phys. Rev. B. - 1994. - Vol. 49, Is. 14. - P.9891-9897. - ISSN 0163-1829, DOI 10.1103/PhysRevB.49.9891
Примечания : Cited References: 34
Предметные рубрики: DYNAMIC PROPERTIES
SUPERCONDUCTIVITY
GAP
LA2CUO4
BI2SR2CACU2O8
PHOTOEMISSION
SPECTROSCOPY
SPECTRA
MODEL
BAND
Аннотация: A generalized tight-binding method to calculate quasiparticle band structure and density of states in strongly correlated systems is presented. The band structures of undoped and weakly hole-doped CuO2 layer are calculated. The insulator gap has a charge transfer nature with a minor contribution from a Cu-O Coulomb interaction. Doping results in the appearance of an in-gap state with a simultaneous decrease of the density of states at the band edges in agreement with small cluster results and experimental data.
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14.

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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15.

Вид документа : Однотомное издание
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Shneyder E. I., Togushova Yu.N., Gavrichkov V. A., Korshunov M. M.
Заглавие : Magnetic mechanisms of pairing in strongly correlated electron system of copper oxides [Electronic resource]
Место публикации : arXiv. - 2015. - Ст.eprint arXiv:1510.08640
Примечания : Cited References: 214. - The authors acknowledge support from FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK 16.740.12.0731 and GK 16.740.11.0740), RFBR (Grants 12-02-31534 and 12-02-31597), Siberian Federal University (Theme #F-11), Governmental support of leading scientific schools of Russia (NSh-1044.2012.2), Program of SB RAS #44, Presidium of RAS program #20.7. EIS, IAM, and MMK are grateful to The Dynasty Foundation and ICFPM forthe financial supportIn book.: Recent advances in superconductivity research", ed. by C.B. Taylor, 321 p., Nova Science Publishers Inc. New York, 2013 ISBN: 978-1-62618-406-0, Chapter 6
Предметные рубрики: Condensed matter-- Strongly correlated electrons
Superconductivity
Ключевые слова (''Своб.индексиров.''): strong electronic correlations--cuprates--hubbard operators--electronic structure--quantum phase transitions--magnetic mechanism of pairing
Аннотация: The multielectron LDA+GTB approach has been developed to calculate electronic structure of strongly correlated cuprates. At low energies the effective Hamiltonian of the t−t′−t"−t⊥−J∗−J⊥-model has been derived with parameters coming from the ab initio calculation for LSCO. The electronic structure of LSCO has been calculated self-consistently with the short-range antiferromagnetic order for various doping level. Two Lifshitz-type quantum phase transitions with Fermi surface topology changes have been found at dopings xc1=0.15 and xc2=0.24. Its effect on normal and superconducting properties has been calculated. The interatomic exchange parameter and its pressure dependence has been calculated within LDA+GTB scheme. The magnetic mechanisms of d-wave pairing induced by static and dynamical spin correlations are discussed. Simultaneous treatment of magnetic and phonon pairing results in the conclusion that both contributions are of the same order. For two layer cuprates like YBCO the interlayer hopping and exchange effects on the electronic structure and doping dependence of Tc is discussed as well as the Coulomb interaction induced mechanism of pairing.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Comparison of the electronic structure of the Hubbard and t - J models within the cluster perturbation theory
Коллективы : RFBR [13-02-01395-a, 14-02-31677-mol-a, 14-02-00186-a]; Ministry of Education and Science of Russia [3085, SibFU 2014 GF-2]; [NSh-2886.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 90, Is. 24. - Ст.245104. - ISSN 1098-0121, DOI 10.1103/PhysRevB.90.245104. - ISSN 1550-235X
Примечания : Cited References: 37. - This work is supported by RFBR (Grants No. 13-02-01395-a, No. 14-02-31677-mol-a, and No. 14-02-00186-a), the Ministry of Education and Science of Russia (Government Contract No. 3085, SibFU 2014 GF-2), and a grant of the Russian President (Grant No. NSh-2886.2014.2).
Предметные рубрики: FERMION SYSTEMS
SUPERCONDUCTIVITY
METAL
Аннотация: Electronic dispersion and density of states (DOS) have been calculated for the Hubbard model and the t−J and t−J∗ models with three-site correlated hopping by the cluster perturbation theory. We have found a rather strong quantitative difference both in dispersion and DOS at all doping for the Hubbard and t−J models at the energy scale ω≳t. The three-site correlated hopping addition results in an almost negligible difference for the Hubbard and t−J∗ models. Close to the Fermi energy, at the scale ω≲J, the electronic structure of all three models is similar. We have found the line of zeros of the Green function for the t−J model that has been previously obtained for the Hubbard model by cellular dynamical mean-field theory calculations.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Ovchinnikov S. G., Singh D. J.
Заглавие : Effect of frustrations on magnetism in the Ru double perovskite Sr2YRuO6
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2003. - Vol. 68, Is. 2. - Ст.24409. - ISSN 1098-0121, DOI 10.1103/PhysRevB.68.024409
Примечания : Cited References: 24
Предметные рубрики: MOTT TRANSITION
LATTICE
SPIN
ANTIFERROMAGNETISM
SUPERCONDUCTIVITY
FERROMAGNETISM
Аннотация: Localized Ru5+ spins in Sr2YRuO6 form a fcc lattice with an antiferromagnetic (AFM) nearest-neighbor (NN) coupling J approximate to 25 meV and rather low Neel temperature T-N= 26 K. Analysis of the electronic structure of Sr2RuO4 results in the effective Heisenberg model. We have studied the effect of frustrations on the AFM type-I structure of Sr2YRuO6 in the spin-wave approximation. In the model with only NN coupling the AFM state is unstable due to frustrations, and T-N = 0. Stabilization of the AFM state occurs due to the next-nearest-neighbor coupling I or due to the magnetic anisotropy D. Very small values D/J similar to I/J less than or equal to 10(-3) are enough to obtain the experimental values of T-N and sublattice magnetization m = 1.85 mu(B) /Ru (62% from the nominal S = 3/2 value).
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I.
Заглавие : Doping evolution of itinerant magnetic fluctuations in Fe-based pnictides
Коллективы :
Место публикации : Europhys. Lett. - 2008. - Vol. 83, Is. 6. - Ст.67003. - ISSN 0295-5075, DOI 10.1209/0295-5075/83/67003
Примечания : Cited References: 18. - We would like to thank B. BUCHNER, S.-L. DRECHSLER, D. EFREMOV, P. FULDE, I. MAZIN, R. MOESSNER and D. PARKER for useful discussions. IE acknowledges support from Volkswagen Foundation.
Предметные рубрики: SUPERCONDUCTIVITY
ORDER
Аннотация: Employing the four-band tight-binding model, we study theoretically the doping dependence of the spin response in the normal state of novel Fe-based pnictide superconductors. We show that the commensurate spin density wave (SDW) transition that arises due to interband scattering between the hole alpha-pockets and the electron beta-pockets disappears already at the doping concentration x approximate to 0.04 reflecting the evolution of the Fermi surfaces. Correspondingly, with further increase of the doping the antiferromagnetic fluctuations are suppressed for x 0.1 and the imaginary part of the spin susceptibility at antiferromagnetic wave vector becomes nearly temperature independent. At the same time, we observe that the uniform susceptibility deviates from the Pauli-like behavior and is increasing with increasing temperature reflecting the activation processes for the alpha-Fermi surfaces up to temperatures of about T = 800 K. With increase of the doping the absolute value of the uniform susceptibility lowers and its temperature dependence changes. In particular, it is a constant at low temperatures and then decreases with increasing temperature. We discuss our results in a context of recent experimental data. Copyright (C) EPLA, 2008
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komarov K. K., Dzebisashvili D. M.
Заглавие : Effect of Coulomb repulsion on the London penetration depth in cuprate superconductors [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1912.04577
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 55. - The work was financially supported by the Presidium of the Russian Academy of Sciences the Program No.12 ”Fundamental problems of high-temperature superconductivity”, the Russian Foundation for Basic Research (project #18-02-00837, #20-32-70059), the Government of Krasnoyarsk Region, the Krasnoyarsk Regional Science and Technology Support Fund (projects: #18-42-240014 ”One-orbit effective model of an ensemble of spin-polaron quasiparticles in the problem of describing the intermediate state and pseudogap behavior of cuprate superconductors” and #18-42-243002 ”Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors”). The work of K.K.K. was supported by the Council for Grants of the President of the Russian Federation (project MK-3722.2018.2).
Предметные рубрики: Superconductivity
Strongly Correlated Electrons
Аннотация: We study the effect of Coulomb repulsion between oxygen holes on the London penetration depth λ based on the concept of spin-polaron nature of Fermi quasiparticles in cuprates superconductors. It is shown that for the generally accepted values of the parameters of the spin-fermion model, taking into account the Coulomb interaction, both the one-site Hubbard Up and interaction between the holes on next-nearest-neighbor oxygen ions V2, allows one to achieve a much better agreement of the calculated temperature dependencies of the value λ−2 with the experimental data in La2−xSrxCuO4 with optimal doping.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article
Место публикации : Low Temp. Phys.: American Institute of Physics, 2012. - Vol. 38, Is. 9. - P.874-879. - ISSN 1063-777X, DOI 10.1063/1.4752091
Примечания : Cited References: 59. - We acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N. M. Plakida, and N. V. Prokof'ev. M. Yu. K's work was supported by RFBR Grant No 11-02-00741-a.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
2-BAND HUBBARD-MODEL
LOW ELECTRON-DENSITY
FRACTIONAL-STATISTICS
PHASE-SEPARATION
SUPERCONDUCTIVITY
GAS
ENHANCEMENT
MECHANISM
Ключевые слова (''Своб.индексиров.''): d-wave superconductivity--electron density--electron spin polarisation--high-temperature superconductors--hubbard model--superconducting transition temperature--t-j model--two-dimensional electron gas
Аннотация: We demonstrate the possibility of triplet p-wave pairing at low electron density a large number of models such as 3D and 2D Fermi-gas models with hard-core repulsion, 3D and 2D Hubbard models, and the Shubin-Vonsovsky model. The critical temperature for p-wave pairing can be considerably higher in the spin-polarized case or even in a two-band situation at low density and can reach experimentally observable values of 1–5 K. We also discuss briefly the d-wave pairing and high-Tc superconductivity with Tc ∼ 100 K which arise in the extended Hubbard model and in the generalized t-Jmodel when close to half-filling.
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