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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Кузьмин, Валерий Ипполитович, Николаев, Сергей Викторович
Заглавие : Исследование аномалий электронной дисперсии в модели Хаббарда, t-J- и t-J*-модели в рамках кластерной теории возмущений в представлении Х-операторов
Коллективы : Сибирский молодежный семинар по высокотемпературной сверхпроводимости и физике наноструктур – ОКНО 2014 (X; 13 - 14 ноября 2014 г.; Новосибирск)
Место публикации : Вестник НГУ. Физика. - 2015. - Т. 10, Вып. 1. - С. 50-56. - ISSN 1818-7994
Примечания : Библиогр.: 23. - Работа выполнена при финансовой поддержке Российского научного фонда (проект № 14-12-00061).
Ключевые слова (''Своб.индексиров.''): высокотемпературная сверхпроводимость--электронная структура купратов--высокоэнергетические кинки--кластерные теории--модель хаббарда--t-j-модель--high-temperature superconductivityory--electronic structure of cuprates--high-energy kinks--cluster perturbation theory--hubbard model--t-j-model
Аннотация: В рамках кластерной теории возмущений в представлении Х-операторов Хаббарда рассчитана энергетическая структура электронов в модели Хаббарда, t-J- и t-J *-модели с учетом уширения спектральных линий, соответствующего экспериментам по фотоэмиссионной спектроскопии с угловым разрешением. При энергиях порядка интеграла перескока t в полученных спектрах наблюдаются аномалии, схожие с высокоэнергетическими кинками, наблюдаемыми в экспериментах по фотоэмиссионной спектроскопии с угловым разрешением. Исследовано поведение высокоэнергетических аномалий электронной дисперсии при изменениях величины допирования и параметра кулоновского отталкивания. Проанализировано влияние трехцентровых коррелированных перескоков на результаты расчета.The electronic structure with the spectral line broadening corresponding to the angle-resolved photoemission spectroscopy resolution has been calculated for the Hubbard model, t-J and t-J * models within the norm-conserving cluster perturbation theory. The electronic dispersion anomalies similar to the high-energy kinks observed in the angle-resolved photoemission spectroscopy experiments are obtained at the energy scale of order of the hopping integral t. The doping dependence of the high-energy anomalies for different Coulomb repulsion values is discussed. The influence of the three-site correlated hopping on the results is analyzed.
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2.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Kozlov P. A., Makarov I. A., Ovchinnikov S. G.
Заглавие : Transition Between Large and Small Polaron States in the Electronic Structure of HTSC Cuprates
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.P2.11. - P.153. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 3
Ключевые слова (''Своб.индексиров.''): cuprates--strong electron correlations--electron-phonon interaction--polaron--franck-condon
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3.

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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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : The strong electron correlation effects in XAFS spectra of HTSC cuprates
Место публикации : J. Phys. IV. - 1997. - Vol. 7: 9th International Conference on X-Ray Absorption Fine Structure (AUG 26-30, 1996, GRENOBLE, FRANCE), Is. C2. - P.183-185. - ISSN 1155-4339
Примечания : Cited References: 11
Предметные рубрики: X-RAY-ABSORPTION
MULTIPLE-SCATTERING ANALYSIS
EDGE STRUCTURE
LA2CUO4
XANES
Аннотация: Theoretical XAFS spectra of highly correlated copper oxides have been presented as a product of a single-electron part obtained by the SCF X alpha- SW method, and a multi-electron part obtained by the multi-band multi-electron p-d model. The main line of CuK-spectrum of La2CuO4 was aligned to the Cud(10) (L) under bar configuration and the single satellite line was aligned to the Cud(9). Comparison of the theoretical data with the experimental ones shows that the ground state of the two-holes in the CuO4 doped cell is triplet. The last conclusion has been confirmed by analysis of CuL2,3-spectra of two-hole impurity states of doped CuO4 cell. Another interesting future of CuL2,3-spectra a peak 2.8 eV higher the threshold was aligned to the transitions into quasi-stationary states due to existence of a high barrier in the Cud-state potential.
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5.

Вид документа : Статья из сборника (однотомник)
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-Tc cuprates
Коллективы : International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials, Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting
Место публикации : Seventh International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials and Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting: May 13-16, 2009, Beijing, China. - Ст.S1E0900
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6.

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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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : The effective Hamiltonian for cuprates at different energy scales
Коллективы : International Conference on Magnetism
Место публикации : J. Magn. Magn. Mater. - 2007. - Vol. 310, Is. 2, Part1. - С. E93-E95. - MAR. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2006.10.575
Примечания : Cited Reference Count: 13
Аннотация: A multiband p - d model describes electronic properties of cuprates in the large energy scale similar to U similar to 10 eV. In the strong electron correlation ( SEC) limit we project out double occupied intra- atomic states and obtain the singlet - triplet t - t' - t'' - J(*) model at scale similar to Omega approximate to 0. 5 eV, where Omega is the excitation energy between two- hole singlet and triplet states. At smaller energies similar to J one gets the usual t - t' - t'' - J(*) model. At energies similar to omega(D) one has to add electron - phonon interaction, and the low- energy effective Hamiltonian with magnetic and phonon mechanisms of pairing is constructed in SEC limit with parameters calculated from the ab initio approach. Magnetic mechanism of pairing results in a very high value of the critical temperature T-c while electron - phonon interaction suppresses d- pairing to the T-c similar to 100 K. (c) 2006 Elsevier B. V. All rights reserved.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shklyaev A. A., Barabanov A. F.
Заглавие : The effect of spin correlations on a superconducting phase of the spin polarons in 2D Kondo lattice
Место публикации : J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 1. - ISSN 17426588 (ISSN), DOI 10.1088/1742-6596/200/1/012217
Ключевые слова (''Своб.индексиров.''): antiferromagnets--concentration dependence--cuprates--experimental data--hopping integrals--kondo lattice model--kondo lattices--magnetic correlation--spin correlations--spin polaron--superconducting phase--superconducting phase transitions--temperature dependence--copper compounds--correlators--magnetism--phase diagrams--polarons--superconducting magnets--superconductivity--phase transitions
Аннотация: The effect of the magnetic correlators on the spin polaron superconducting phase is studied in terms of 2D Kondo lattice model. It is shown that hopping integrals are renormalized by the magnetic correlators and as a result the Tc phase diagram is changing significantly. By computation the effect of magnetic correlation functions on the concentration dependence of T c was analysed and their substantial role in description of doped antiferromagnets is demonstrated. The obtained phase diagram is in qualitative agreement with experimental data for temperature dependence of the superconducting phase transition with d-type symmetry in cuprates. © 2010 IOP Publishing Ltd.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Zakharova E. V.
Заглавие : Temperature evolution of spin-polaron in-gap states in undoped antiferromagnetic cuprates
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 8. - P1401-1406. - ISSN 1063-7834, DOI 10.1134/S1063783408080027
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research (project nos. 06-02-16100 and 0602- 90537-BNTS), the Presidium of the Russian Academy of Sciences (program "Quantum Macrophysics"), and INTAS (YS grant no. 05-109-4891).
Предметные рубрики: J MODEL
LA2-XSRXCUO4
SUPERCONDUCTORS
BAND
Аннотация: The temperature evolution of in-gap states created by the spin polaron effect and located within the gap with charge transfer between the valence and conduction bands is studied for the case of strong electron correlations using the t-t'-t ''-J model of antiferromagnetic undoped cuprates. The effect of temperature is taken into account by temperature renormalization of the magnon concentration, which is calculated using the Heisenberg model with inclusion of weak interlayer exchange and weak in-plane spin anisotropy, and by introducing a Lorentzian with a temperature-dependent half-width in the form corresponding to the marginal Fermi liquid model. With increasing temperature, the spectral weight of the in-gap state, which is proportional to the magnon concentration, grows leading to an increased intensity of the corresponding peak of the spectral function in all points of the Brillouin zone. At points (pi/2, pi/2) and (pi, 0), the main peak is approached by the satellite peak related to the in-gap band and, at points (0, 0) and (pi, pi), the peaks move away from each other.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Kuzmin V. I., Nikolaev S. V., Visotin M. A.
Заглавие : Temperature and doping dependent short range antifferomagnetic order and pseudogap formation in hole-doped cuprates
Коллективы : International Conference on Supercondactivity and Magnetism
Место публикации : 8th International conference on supercondactivity and magnetism (ICSM2023): abstract book. - 2023. - Ст.159. - P.248
Примечания : Cited References: 1
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molchanova A. D., Moshkina E. M., Molokeev M. S., Tropina E. V., Bovina A. F., Boldyrev K. N.
Заглавие : Synthesis and optical properties of nickel-doped copper metaborate crystals
Колич.характеристики :6 с
Место публикации : Opt. Spectrosc. - 2023. - Vol. 131, Is. 8. - P.717-722. - ISSN 0030400X (ISSN), DOI 10.1134/S0030400X23060127. - ISSN 15626911 (eISSN)
Примечания : Cited References: 18. - The study was performed with the support of Russian Science Foundation, RSF grant no. 19-12-00413
Аннотация: This work presents information on the growth and spectroscopic study of single crystals of copper metaborate doped with nickel Cu1–xNixB2O4 (x = 0.05, 0.1). In the absorption spectra of both crystals, satellites related to Cu centers distorted by impurity Ni atoms were observed near the lines of zero phonon transitions. Polarization studies in the isotropic ab-plane of the tetragonal crystal Cu1–xNixB2O4 show the presence of linear magnetic dichroism in the magnetically ordered state, which was previously observed both in manganese-doped and undoped copper metaborates CuB2O4. The temperature of magnetic phase transitions into the collinear antiferromagnetic and into helicoidal structures, TN = 19.1 K and T * = 8.6 K, respectively, were determined from the temperature dependence of the dichroic signal.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molchanova A. D., Moshkina E. M., Molokeev M. S., Tropina E. V., Bovina A. F., Boldyrev K. N.
Заглавие : Synthesis and optical properties of nickel-doped copper metaborate crystals
Место публикации : Opt. Spectrosc. - 2022. - Vol. 130, Is. 1. - P.105-109. - ISSN 0030400X (ISSN), DOI 10.21883/EOS.2022.01.52994.41-21. - ISSN 15626911 (eISSN)
Примечания : Cited References: 18. - The study was performed with the support of Russian Science Foundation, RSF grant № 19-12-00413
Аннотация: This work presents information on the growth and spectroscopic study of single crystals of copper metaborate doped with nickel Cu1–xNixB2O4 (x = 0.05, 0.1). In the absorption spectra of both crystals, satellites related to Cu centers distorted by impurity Ni atoms were observed near the lines of zero phonon transitions. Polarization studies in the isotropic ab-plane of the tetragonal crystal Cu1–xNixB2O4 show the presence of linear magnetic dichroism in the magnetically ordered state, which was previously observed both in manganese-doped and undoped copper metaborates CuB2O4. The temperature of magnetic phase transitions into the collinear antiferromagnetic and into helicoidal structures, TN = 19.1 K and T* = 8.6 K, respectively, were determined from the temperature dependence of the dichroic signal.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Komarov K. K., Barabanov A. F.
Заглавие : Strong Spin-Charge Coupling and Its Manifestation in the Quasiparticle Structure, Cooper Instability, and Electromagnetic Properties of Cuprates
Коллективы : "Fundamental problems in high-temperature superconductivity" of the Presidium of the Russian Academy of Sciences, Russian Foundation for Basic Research [12, 18-02-00837]; Krasnoyarsk Krai Foundation for Supporting the Scientific and Technical Activity [18-42-243002, 18-42-243018, 18-42-240014]; President of the Russian Federation [MK-37.2019.2, MK-3722.2018.2]; Russian Foundation for Basic Research [19-02-00509]
Место публикации : J. Exp. Theor. Phys. - 2019. - Vol. 128, Is. 6. - P.885-898. - ISSN 1063-7761, DOI 10.1134/S1063776119050078. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 83. - This study was supported by the program no. 12 "Fundamental problems in high-temperature superconductivity" of the Presidium of the Russian Academy of Sciences, Russian Foundation for Basic Research (project no. 18-02-00837), the administration of the Krasnoyarsk Krai, Krasnoyarsk Krai Foundation for Supporting the Scientific and Technical Activity under project nos. 18-42-243002 (Manifestations of spin-nematic correlations in spectral characteristics of the electronic structure and their influence on the properties of cuprate superconductors in applications), 18-42-243018 (Contact phenomena and magnetic disorder in the problem of formation and detection of topologically protected edge states in semiconducting nanostructures), and 18-42-240014 (Single-orbital effective model of an ensemble of spin-polaron quasiparticles in the problem of description of the intermediate state and pseudogap behavior of cuprate superconductors), as well as the Council for grants from the President of the Russian Federation (project nos. MK-37.2019.2 and MK-3722.2018.2). The work of A.F.B was supported by the Russian Foundation for Basic Research (project no. 19-02-00509).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
INTERSITE COULOMB REPULSION
Аннотация: The Fermi excitation spectrum, the problem of Cooper instability, and the Londons magnetic field penetration depth in cuprate superconductors are considered using the unified conception based on accounting for the strong coupling between the spin of copper ions and holes at oxygen ions. This coupling leads to strong renormalization of the primary spectrum of oxygen holes with the formation of spin-polaron quasiparticles. Analysis of Cooper instability performed using the spin-polaron concept for different channels has shown that only the superconducting d-wave pairing occurs in the ensemble of spin-polaron quasiparticles, and there are no solutions corresponding to the s-wave pairing. It has been demonstrated that the superconducting d-wave pairing is not suppressed by the Coulomb repulsion of holes located at neighboring oxygen ions. This effect is due to peculiarities in the crystallographic structure of the CuO2 plane and the aforementioned strong spin-fermion coupling. As a result, such interaction of holes is omitted in the kernel of the integral equation for the superconducting order parameter with the d-wave symmetry. It has been shown the Hubbard repulsion of holes and their interaction for the second coordination sphere of the oxygen sublattice for actual intensities of the interaction do not suppress the d-wave type of superconductivity. For the spin-polaron ensemble, we have analyzed the dependence of the Londons magnetic field penetration depth on the temperature and hole concentration. It has been established that the peculiarities of this dependence are closely related to specific features of the spin-polaron spectrum.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Barabanov A. F.
Заглавие : Spin-polaron concept in the theory of normal and superconducting states of cuprates
Коллективы : Russian Foundation for Basic Research (RFBR)Russian Foundation for Basic Research (RFBR) [18-02-00837, 19-02-00509, 20-32-70059]; Government of Krasnoyarsk Region; Krasnoyarsk Region Science and Technology Support Fund [18-42-240014]; RFBRRussian Foundation for Basic Research (RFBR) [19-12-50116]
Место публикации : Phys. Usp. - 2021. - Vol. 64, Is. 7. - P.641-670. - ISSN 1063-7869, DOI 10.3367/UFNe.2020.08.038829. - ISSN 1468-4780(eISSN)
Примечания : Cited References: 328. - The authors' study was supported by the Russian Foundation for Basic Research (RFBR) within project nos. 18-02-00837, 19-02-00509, and 20-32-70059, and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund within project no. 18-42-240014 "Single-orbital effective model of an ensemble of spin-polaron quasiparticles in the problem of describing the intermediate state and pseudogap behavior of cuprate superconductors.'' The review was carried out with support from the RFBR within the Expansion competition (project no. 19-12-50116)
Предметные рубрики: HIGH-TC SUPERCONDUCTIVITY
CHARGE-DENSITY-WAVE
HIGH-TEMPERATURE SUPERCONDUCTORS
Аннотация: The review discusses the emergence of the spinfermion model of cuprates and the formation of the spin-polaron concept of the electronic structure of hole-doped cuprate superconductors. This concept has allowed describing the properties of cuprates in the normal phase as well as the features of superconducting pairing in the unified approach. The derivation of the spin-fermion model from the Emery model in the regime of strong electronic correlations is described, demonstrating the appearance of strong coupling between the spins of copper ions and holes on oxygen ions. Such a strong interaction against the background of the singlet state of the spin subsystem of copper ions (quantum spin liquid) leads to the formation of special Fermi quasiparticlesDnonlocal spin polarons. Under doping, the spin-polaron ensemble exhibits instability with respect to superconducting d-wave pairing, whereas superconducting swave pairing is not implemented. At the optimal doping, the transition to the superconducting phase occurs at temperatures corresponding to experimental data. It is shown that the superconducting d-wave pairing of spin-polaron quasiparticles is not suppressed by the Coulomb repulsion of holes located on neighboring oxygen ions. It is emphasized that, when the spectral characteristics of spin-polaron quasiparticles are taken into account, the calculated temperature and doping dependences of the London penetration depth are in good agreement with experimental data.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G., Sherman A.V.
Заглавие : Spin fluctuation and spin-exciton mechanisms of superconductivity in Cuprates
Место публикации : The Physics of Metals and Metallography. - 2006. - Vol. 101, Suppl. 1. - P.S6–S9. - DOI 10.1134/S0031918X06130035
Примечания : Cited References: 19. - Russian Foundation for Basic Research (grant no. 03-02-16124); Russian Academy of Sciences, Quantum Macrophysics Program; INTAS (grant no. 01-0654); ETF (grant no. 5548); Siberian Division of the Russian Academy of Sciences (Lavrent’ev Contest for Young Scientists); the Dynasty Foundation; and ICFPM.
Аннотация: The properties of the normal and superconductive phases of p- and n-type cuprates are investigated in terms of the appropriate low-energy models in the approximation beyond Hubbard I with inclusion of spin fluctuations. The comparison of the singlet–triplet t–J model with the t–J model shows that the spin–exciton mechanism originated from the singlet–triplet hybridization contributes only slightly to the phase diagram of the p-type systems.
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16.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S., Korshunov M., Shneyder E.
Заглавие : Short magnetic order and quantum phase transition in high-Tc cuprates
Коллективы : International Conference on Magnetism
Место публикации : 18th International Conference on Magnetism (ICM-2009). - 2009. - Ст.Mo-A-5.1-03
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G., Shneider E. I.
Заглавие : Reconstruction of the Fermi surface of HTSC cuprates in a high magnetic field
Коллективы : Russian Foundation for Basic Research [09-02-00127]; Siberian Branch and the Ural Division, Russian Academy of Sciences [40]; Presidium of the Russian Academy of Sciences [5.7]
Место публикации : JETP Letters. - 2009. - Vol. 89, Is. 12. - P.632-637. - ISSN 0021-3640, DOI 10.1134/S002136400912008X
Примечания : Cited References: 19. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Siberian Branch and the Ural Division, Russian Academy of Sciences (integration project no. 40), and the Presidium of the Russian Academy of Sciences (program no. 5.7).
Предметные рубрики: T-J MODEL
COPPER OXIDES
ELECTRON
SPECTRUM
BAND
Аннотация: The effect of a high magnetic field on the electronic structure of HTSC cuprates is considered. The study is performed in the t-t'-taEuro(3)-J* model, and the high magnetic field effect is taken into account not only as the Zeeman splitting of the one-electron levels, but also in the occupation numbers of the states with different spin projections and in the formation of the spin correlation functions. The field is assumed to be high enough to align all of the spins along the field. As a result, the Fermi surface reconstruction is obtained from four hole pockets about the nodal point (pi/2, pi/2) in the paramagnetic phase to a large hole pocket about the point (pi, pi) in the ferromagnetic phase. As the magnetic field strength decreases, a number of quantum phase transitions are revealed; they are manifested in the changed Fermi surface topology. The Fermi surface reconstruction with a decreasing field is qualitatively the same as that with an increasing doping degree in the absence of a magnetic field.
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18.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Nikolaev S. N., Shneyder E. I.
Заглавие : Quantum phase transitions and superconductivity in single- and two-layer cuprates in the multiband theory of Hubbard fermions
Коллективы : Ettore Majorana Foundation, Centre for Scientific Culture, Rome International Center for Materials Science, International School of Solid State Physics, "Phase separation and Superstripes in High Temperature Superconductors and Related Materials", Int. Conf. (55; 2012 ; July ; 11-17; Erice (Sicily), Italy)
Место публикации : International conferences «Phase separation and Superstripes in High Temperature Superconductors and Related Materials (Superstripes-2012)». - 2012. - P.128
Аннотация: We consider the doping dependence of the normal and superconducting properties of LaSrCuO and YBaCuO in the low energy effective model based on the ab initio LDA+GTB calculations. With doping we have found a concentration region with electronic instability of the uniform state. We have shown that two quantum phase transitions (QPT) of the Lifshitz type correspond well to the experimental phase diagram. For superconducting state we have considered both magnetic and phonon mechanisms of pairing.
Программа конференции,
Материалы конференции
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Makarov I. A., Shneyder E. I.
Заглавие : Quantum phase transitions and superconductivity in single- and two-layer cuprates in the multiband theory of Hubbard fermions
Место публикации : J. Supercond. Nov. Magn. - 2013. - Vol. 26, Is. 8. - P.2607-2609. - ISSN 1557-1939, DOI 10.1007/s10948-013-2144-1. - ISSN 1557-1947
Аннотация: We consider the doping dependence of the normal and superconducting properties of La2Sr2−x CuO2 and YBa2Cu3O7 in the low energy effective model based on the ab initio LDA+GTB calculations. With doping we have found a concentration region with electronic instability of the uniform state. We have shown that two quantum phase transitions (QPT) of the Lifshitz type correspond well to the experimental phase diagram. For superconducting state we have considered both magnetic and phonon mechanisms of pairing.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Borisov A. A., Gavrichkov V. A., Korshunov M. M.
Заглавие : Prediction of the in-gap states above the top of the valence band in undoped insulating cuprates due to the spin-polaron effect
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2004. - Vol. 16, Is. 8. - PL93-L100. - ISSN 0953-8984, DOI 10.1088/0953-8984/16/8/L04
Примечания : Cited References: 25
Предметные рубрики: ELECTRONIC-STRUCTURE
LA2-XSRXCUO4
MODEL
ANTIFERROMAGNETISM
SPECTRA
OXIDES
Ключевые слова (''Своб.индексиров.''): quasiparticle band structure--spin-polaron effect--antiferromagnetic materials--approximation theory--doping (additives)--electronic structure--hamiltonians--insulation--magnetic fields--strontium compounds--thermal effects--lanthanum compounds
Аннотация: In the framework of the generalized tight binding method we have calculated the quasiparticle band structure and the spectral functions of the undoped cuprates such as La2CuO4, Sr2CUO2Cl2 etc. Due to spin fluctuations the in-gap state appears above the top of the valence band in the undoped antiferromagnetic insulator similar to in-gap states induced by hole doping. In the ARPES experiments the in-gap states can be detected as weak low energy satellites.
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