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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 журнала
Шифр издания :
Автор(ы) : GORYACHEV E. G.
Заглавие : VARIATIONAL APPROACH TO THE 3-PARTICLE PROBLEM IN THE HUBBARD-MODEL - THE EXACT RESULT
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 102, Is. 4. - P1280-1285. - ISSN 0044-4510
Примечания : Cited References: 7
Аннотация: A well-defined procedure for the linearization of the equations of motions, which is based on the stationary principle, is proposed. In the special case of a flopped spin in the saturated ferromagnetic state (three-particle problem) the single-particle Green function is found. It is proved that regardless whether the initial (unperturbed) state is a strong coupling band (Bloch representation) or two-level atom system (Hubbard representation) the results for the single-particle Green function coincide for arbitrary values of the hamiltonian constants and electron concentration b up. In the non-trivial limit case U = infinity such a Green function coincides with the exact result of Igarashi - Ruckenstein - Schmitt - Rink [2,3] based on solving the Faddeev equations.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Marienko M. S., Val'kov V. V.
Заглавие : Triplet p-Wave Superconductivity in the Low-Density Extended Hubbard Model with Coulomb Repulsion
Разночтения заглавия :авие SCOPUS: Triplet p-wave superconductivity in the low-density extended hubbard model with Coulomb repulsion
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 12. - P.725-730. - ISSN 0021-3640, DOI 10.1134/S0021364011120083
Примечания : Cited References: 42. - We acknowledge useful with A. V. Chubukov, A.S. Alexandrov, I.A. Fomin, K.I. Kugel, and V. V. Kabanov for stimulating discussions. This work was supported by the Russian Foundation for Basic Research (project nos. 11-02-00708 and 11-02-00741). M.S.M acknowledges the support of the US Department of Energy (award no. DE-FG02-08ER64623, Hofstra University Center for Condensed Matter).
Предметные рубрики: T-J MODEL
FERMI GAS
SUPERFLUID TRANSITION
PHASE-SEPARATION
SYSTEMS
TEMPERATURES
BEHAVIOR
LIQUID
POINT
STATE
Аннотация: We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb repulsion between electrons on neighboring sites in the limit of low electron density (n(el) - 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U V W (U and V are the onsite and the intersite Coulomb repulsions, respectively, and W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Treating many-body quantum systems by means of classical mechanics
Коллективы : International Conference on Nonlinear Dynamics of Electronic Systems
Место публикации : Springer Proceedings in Physics: Springer, 2017. - Vol. 191. - P.37-48. - ISSN 09308989 (ISSN); 9783319478081 (ISBN), DOI 10.1007/978-3-319-47810-4_4
Примечания : Cited References: 16
Ключевые слова (''Своб.индексиров.''): dynamical systems--dynamics--hubbard model--optical lattices--quantum optics--classical mechanics--energy spectra--identical particles--many-body quantum systems--paradigmatic models--quantum many-body systems--quantum physics--semiclassical approaches--quantum theory
Аннотация: Many-body physics of identical particles is commonly believed to be a sovereign territory of Quantum Mechanics. The aim of this contribution is to show that it is actually not the case and one gets useful insights into a quantum many-body system by using the theory of classical dynamical systems. In the contribution we focus on one paradigmatic model of many-body quantum physics - the Bose– Hubbard model which, in particular, describes interacting ultracold Bose atoms in an optical lattice. We show how one can find/deduce the energy spectrum of the Bose–Hubbard model by using a kind of the semiclassical approach. © Springer International Publishing AG 2017.
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5.

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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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Val'kova T. A., Dzebisashvili D. M., Ovchinnikov S. G.
Заглавие : Three-center interactions and magnetic mechanism of superconductivity with dx2-y2-symmetry in the t-J*-model
Коллективы : International Conference on Modern Problems in Superconductivity
Место публикации : Mod. Phys. Lett. B/ International Conference on Modern Problems in Superconductivity (3 ; 2002 ; Sept. ; 9-14 ; Yalta, Ukrain). - 2003. - Vol. 17, Is. 10-12. - P.441-449. - ISSN 0217-9849, DOI 10.1142/S0217984903005469
Примечания : Cited References: 12
Предметные рубрики: BAND HUBBARD-MODEL
Аннотация: The effect of three-center interactions on the formation of a superconducting phase with d(x2-y2)-symmetry is considered using the diagram technique for Hubbard operators and irreducible Green's functions. It is shown that these interactions lead to a decrease in T-c by a factor of several tens.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Baklanov I. O.
Заглавие : The singlet state in the Hubbard model with U=infinity
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 1998. - Vol. 87, Is. 6. - P1159-1166. - ISSN 1063-7761, DOI 10.1134/1.558607
Примечания : Cited References: 16
Предметные рубрики: HOLES
Аннотация: We discuss, in connection with the problem of the ground state in the Hubbard model with U = infinity, the normal (nonmagnetic) N-state of a system over the entire range of electron concentrations n less than or equal to 1. It is found that in a one-particle approximation, e. g., in the generalized Hartree-Fock approximation, the energy epsilon(0)(n) of the N-state is lower than the energy epsilon(FM)(n) of a saturated ferromagnetic state for all values of n. Using the random phase approximation we calculate the dynamical magnetic susceptibility and show that the N-state is stable for all values of n. A formally exact representation is derived for the mass operator of the one-particle electron Green's function, and its expression in the self-consistent Born approximation is obtained. We discuss the first Born approximation and show that when correlations are taken into account, the attenuation vanishes on the Fermi surface and the electron distribution function at T = 0 acquires a Migdal discontinuity, whose magnitude depends on n. The energy of the N-state in this approximation is still lower than epsilon(FM)(n) for n 1.We show that the spin correlation functions are isotropic, which is a characteristic feature of the singlet states of the system. We calculate the spin correlation function for the nearest neighbors in the zeroth approximation as a function of n. Finally, we conclude that the singlet state of the system in the thermodynamic limit is the ground state. (C) 1998 American Institute of Physics. [S1063-7761(98)01712-0].
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kovaleva E. A., Melchakova I., Mikhaleva N. S., Tomilin F. N., Ovchinnikov S. G., Baek W., Pomogaev V. A., Avramov P. V., Kuzubov A. A.
Заглавие : The role of strong electron correlations in determination of band structure and charge distribution of transition metal dihalide monolayers
Место публикации : J. Phys. Chem. Solids. - 2019. - Vol. 134. - P.324-332. - ISSN 00223697 (ISSN), DOI 10.1016/j.jpcs.2019.05.036
Примечания : Cited References: 44. - This work was supported by the government contract of the Ministry of Education and Science of the Russian Federation, Russia to Siberian Federal University (Grant No. 16.1455.2017/PCh ) and Russian Foundation for Basic Research (RFBR), Russia (Grant No. 16-32-60003 mol_a_dk), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: “Quantum chemical modeling of Bychkov-Rashba interfaces based on transition metal compounds and nanoscaled organic fragments” (Project No. 18-43-243011). The authors would like to thank Joint Supercomputer Center of RAS , Moscow; Center of Equipment for Joint Use of Siberian Federal University , Krasnoyarsk; and Information Technology Center, Novosibirsk State University for providing the access to their supercomputers. N.S.M. acknowledges the financial support of the RFBR , through the research project No. 16-32-60003 mol_a_dk. E.A. Kovaleva is grateful to the Foundation for Assistance to Small Innovative Enterprises (FASIE), Russia (Project no. 0033639 ). W.B. and P.A. gratefully acknowledge the financial support of National Research Foundation of Republic of Korea under the Grant No. NRF-2017R1A2B4004440.
Аннотация: Electronic structure and magnetic properties of the family of first-row transition metal dihalides (TMHal2, TM = V, Cr, Mn, Fe, Co, Ni; H = Br, I) monolayers were studied by means of density functional theory. Strong electron correlations were taken into account by implementing Hubbard U correction in a simplified scheme proposed by Dudarev et al. (Ueff). Ueff correction essentially affects electronic structure of TMHal2 widening the band gap and witnessing their highly spin-polarized nature. Two different ligand orientations namely, H and T configurations of monolayers were considered. Unlike others, FeHal2 monolayers tend to form H structure when Ueff correction is included. © 2019 Elsevier Ltd
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Yakimov L. E.
Заглавие : The role of orbital ordering in the formation of electron structure in undoped LaMnO3 manganites in the regime of strong electron correlations
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 6. - P972-985. - ISSN 1063-7761, DOI 10.1134/S1063776106060112
Примечания : Cited References: 25
Предметные рубрики: COLOSSAL MAGNETORESISTIVE OXIDES
DOUBLE EXCHANGE
BAND
MODEL
Ключевые слова (''Своб.индексиров.''): computational methods--correlation methods--doping (additives)--electrons--ferromagnetic materials--lanthanum compounds--paramagnetic materials--intraatomic electron correlations--mott hubbard correlation gap--orbital ordering--paramagnetic phases--electronic structure
Аннотация: The electron structure of undoped LaMnO3 and slightly doped La1-xSrxMnO3 manganites has been calculated within the framework of a generalized tight binding method with explicit allowance for strong intra-atomic electron correlations. According to the results of these calculations, the ground state in orbitally disordered undoped LaMnO3 ferromagnets would be metallic despite the Mott-Hubbard correlation gap in the spectrum of quasiparticles. Owing to the orbital ordering, the insulating state is stabilized in both antiferromagnetic and paramagnetic phases. In-gap states of a polaron nature with a spectral weight proportional to the dopant concentration have been found near the top of the valence band in La1-xSrxMnO3. As the doping level increases, a metal state appears in the ferromagnetic phase, which has a metallic character for one spin subband and an insulating character for the other subband (representing the so-called half-metallic state).
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Golovnya A. A., Dzebisashvili D. M.
Заглавие : The role of anomalous strength operator in the high-T (c) superconductivity theory
Разночтения заглавия :авие SCOPUS: The role of anomalous strength operator in the high- Tc superconductivity theory
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P465-466. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.202
Примечания : Cited References: 3
Ключевые слова (''Своб.индексиров.''): superconductivity--t-j-model--superconductivity--t- j-model--approximation theory--frequencies--mathematical operators--numerical methods--superconducting transition temperature--superconductivity--hubbard operator--matsubara frequency--t- j-model--high temperature superconductors
Аннотация: The diagram series structure for Matsubara Green's functions in the Hubbard operators representation have been analyzed for the superconducting (SC) phase in the t-J-model. It has been found that the Hubbard operator diagram technique besides anomalous self-energy operator includes also anomalous strength operator (ASO). With account for ASO Gor'kov equations have been written. ASO are shown to be very essential when anomalous averages are calculated. The anomalous self-energy operator and ASO were derived in one-loop approximation. It has turned out that strength operator components depend oil Matsubara frequency. As a result the SC phase is described by infinite set of integral equations. When deriving the equation for transition temperature in SC phase with s- and d-order parameter symmetry this system has been solved exactly. On the basis of numerical calculations it has been found that the account for strength operator components has fully suppressed SC phase with s-order parameter symmetry in the t-J-model. (c) 2006 Elsevier B.V. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger superconductivity in idealized doped graphene
Коллективы : Program of the Division of Physical Sciences of the Russian Academy of Sciences [11.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Council of the President of the Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2014. - Vol. 188. - P.61-66. - ISSN 0038-1098, DOI 10.1016/j.ssc.2014.03.001. - ISSN 1879-2766
Примечания : Cited References: 31. - This work was supported by the Program of the Division of Physical Sciences of the Russian Academy of Sciences (Project 11.3.1), and the Russian Foundation for Basic Research (Projects 14-02-00058 and 14-02-31237). One of the authors (M.M.K.) acknowledges the support of the Council of the President of the Russian Federation (Project MK-526.2013.2), and the Dynasty Foundation.
Предметные рубрики: REPULSIVE INTERACTIONS
HUBBARD-MODEL
SUPERFLUIDITY
INSTABILITY
MECHANISM
DENSITY
SYSTEMS
Ключевые слова (''Своб.индексиров.''): graphene--superconductivity
Аннотация: Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter. (C) 2014 Elsevier Ltd. All rights reserved.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger effect and anomalous pairing in new superconducting systems and graphene
Коллективы : Physics Department of the Russian Academy of Sciences [P.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 118, Is. 6. - P.995-1011. - ISSN 1063-7761, DOI 10.1134/S1063776114060132. - ISSN 1090-6509
Примечания : Cited References: 114. - This study was supported by the Program of the Physics Department of the Russian Academy of Sciences (project no. P.3.1) and the Russian Foundation for Basic Research (project nos. 14-02-00058 and 14-02-31237). The work of two coauthors (M. M. K. and V.A.M) was supported financially by grant no. MK-526.2013.2 of the President of the Russian Federation and the Dynasty Foundation.
Предметные рубрики: P-WAVE SUPERCONDUCTIVITY
EXTENDED HUBBARD-MODEL
NARROW ENERGY-BANDS
2D KONDO-LATTICE
FERMI GAS
REPULSIVE INTERACTIONS
ELECTRON CORRELATIONS
COOPER INSTABILITY
PHASE-DIAGRAM
SPECTRUM
Аннотация: We present a review of theoretical investigations into the Kohn-Luttinger nonphonon superconductivity mechanism in various 3D and 2D repulsive electron systems described by the Fermi-gas, Hubbard, and Shubin-Vonsovsky models. Phase diagrams of the superconducting state are considered, including regions of anomalous s-, p-, and d-wave pairing. The possibility of a strong increase in the superconducting transition temperature T c even for a low electron density is demonstrated by analyzing the spin-polarized case or the two-band situation. The Kohn-Luttinger theory explains or predicts superconductivity in various materials such as heterostructures and semimetals, superlattices and dichalcogenides, high-T c superconductors and heavy-fermion systems, layered organic superconductors, and ultracold Fermi gases in magnetic traps. This theory also describes the anomalous electron transport and peculiar polaron effects in the normal state of these systems. The theory can be useful for explaining the origin of superconductivity and orbital currents (chiral anomaly) in systems with the Dirac spectrum of electrons, including superfluid 3He-A, doped graphene, and topological superconductors.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzmin E. V.
Заглавие : The ground state problem in the infinite-U Hubbard model
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1997. - Vol. 39, Is. 2. - P169-178. - ISSN 1063-7834, DOI 10.1134/1.1130126
Примечания : Cited References: 36
Предметные рубрики: NAGAOKA FERROMAGNETIC STATE
INSTABILITY
HOLES
BAND
Аннотация: The problem of the ground state of the electronic system in the Hubbard model for U=infinity is discussed. The author investigates the normal (singlet or nonmagnetic) N state of the electronic system over the entire range of electron densities n less than or equal to 1. It is shown that the energy of the N state epsilon(0)((1))(n) in a one-particle approximation, such as (e.g.) the extended Hartree-Fock approximation, is lower than the energy of the saturated ferromagnetic FM state epsilon(FM)(n) for all n. The dynamic magnetic susceptibility is calculated in the random phase approximation, and it is shown that the N state is stable over the entire range of electron densities: The static susceptibility (omega=0) does not have a band singularity in the zero-wave vector limit q--0. A formally exact representation is obtained for the mass operator of the one-particle Green's function, and an approximation of this operator is proposed: M-k(E)similar or equal to lambda F(E), where lambda=n(1-n)/(1-n/2)z is the kinematic interaction parameter, z is the number of nearest neighbors, and F(E) is the total single-site Green's function. For an elliptical density of states the integral equation for F(E) is solved exactly, ad it is shown that the spectral intensity rigorously satisfies the sum rule. The calculated energy of the strongly correlated N state epsilon(0)(n)epsilon(FM)(n) for all n, and in light of this relationship the author discusses the hypothesis that the ground state of the system is the normal (singlet) state in the thermodynamic limit. The electron distribution function at T
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Goryachev E. G., Kuzmin E. V., Ovchinnikov S. G.
Заглавие : The electronic-spectrum and the metal-insulator-transition in the hubbard-model
Место публикации : Phys. Lett. A. - 1981. - Vol. 85, Is. 4. - P.236-238. - ISSN 0375-9601, DOI 10.1016/0375-9601(81)90025-6
Примечания : Cited References: 4
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : The electron energy spectrum and superconducting transition temperature of strongly correlated fermions with three-center interactions
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 3. - P608-616. - ISSN 1063-7761, DOI 10.1134/1.1901772
Примечания : Cited References: 29
Предметные рубрики: T-J MODEL
BAND HUBBARD-MODEL
VALENCE BOND STATE
RANGE-ORDER
SYSTEMS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--fermions--ground state--hamiltonians--superconductivity--density of states--electron energy spectrum--strongly correlated fermions--superconducting phase--superconducting transition temperature
Аннотация: The renormalizations of the fermionic spectrum are considered within the framework of the t-J* model taking into account three-center interactions (H-(3)) and magnetic fluctuations. Self-consistent spin dynamics equations for strongly correlated fermions with three-center interactions were obtained to calculate quasi-spin correlators. A numerical self-consistent solution to a system of ten equations was obtained to show that, in the nearest-neighbor approximation, simultaneously including H-(3) and magnetic fluctuations at n n(1) (n(1) approximate to 0.72 for 2t/U = 0.25) caused qualitative changes in the structure of the energy spectrum. A new Van Hove singularity is then induced in the density of states, and an additional maximum appears in the T-c(n) concentration dependence of the temperature of the transition to the superconducting phase with order parameter symmetry of the d(x2-y2) type. (C) 2005 Pleiades Publishing, Inc.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Temperature and concentration dependence of the magnetic short range order and electronic pseudogap in 2D Hubbard model
Коллективы : International Online Workshop on the properties of Functional MAX-materials, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : 1st FunMAX Workshop 2020: Book of Abstracts/ , Ин-т физики им. Л.В. Киренского. - 2020. - P11
Примечания : Cited References: 4. - We acknowledge the Russian Academy of Science Program on High_Tc superconductivity for the financial support.
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17.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Temperature and concentration dependence of the magnetic short range order and electronic pseudogap in 2D Hubbard model
Коллективы : International workshop on functional MAX-materials, Kirensky Institute of Physics
Место публикации : International workshop on functional MAX-materials (1st FunMax). - 2020. - P.9
Примечания : Cited references: 4. - We acknowledge the Russian Academy of Science Program on High_Tc superconductivity for the financial support
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Superconductivity in repulsive fermi-systems at low density
Коллективы : RFBR [11-02-00741]
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2013. - Vol. 26, Is. 9. - P.2809-2815. - ISSN 1557-1939, DOI 10.1007/s10948-013-2262-9
Примечания : Cited References: 57. - The authors acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N.M. Plakida, N.V. Prokof'ev, M. M. Korovushkin, M. A. Mitskan. M. Yu. K. work was supported by RFBR grant No. 11-02-00741.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
FRACTIONAL-STATISTICS
PHASE-SEPARATION
HUBBARD-MODEL
GAS
ENHANCEMENT
MECHANISM
EXCHANGE
PARTICLES
Ключевые слова (''Своб.индексиров.''): anomalous superconductivity--p-wave and d-wave pairings--kohn-luttinger mechanism--shubin-vonsovsky--hubbard and t-j models
Аннотация: In the large variety of models such as 3D and 2D Fermi-gas model with hard-core repulsion, 3D and 2D Hubbard model, and the Shubin-Vonsovsky model, we demonstrate the possibility of triplet p-wave pairing at low electron density. We show that the critical temperature of the p-wave pairing can be strongly increased in a spin-polarized case or in a two-band situation already at low density and reach experimentally feasible values of (1-5) K. We also discuss briefly d-wave pairing and high-T-C superconductivity with T-C similar to 100 K, which arises in the 2D t-J model in the range of parameters realistic for cuprates.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Val’kova T. A., Mitskan V. A.
Заглавие : Superconducting phase with the (d + id) order parameter in an ensemble of Hubbard fermions on the triangular lattice
Место публикации : JETP Letters. - 2015. - Vol. 102, Is. 6. - P.361-366. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364015180162
Примечания : Cited References: 18. - This work was supported by the Russian Foundation for Basic Research, project nos. 13-02-00523 and 14-02-31237
Аннотация: In the framework of the t–J 1–J 2–V model, the integral equation determining the order parameter Δ(p) of the superconducting phase is derived for an ensemble of strongly correlated fermions on a triangular lattice using the diagram technique for the Hubbard operators. Taking into account the interaction between the Hubbard fermions within two coordination spheres, we demonstrate that the exact analytical solution Δ2(p) of this equation for the superconducting phase with the ((dx2−y2+idxy) symmetry can be expressed as a superposition of two chiral basis functions. This gives rise to a new set of nodal points for the complex parameter Δ2(p). Moreover, at some critical value x c of the charge carrier density, we obtain a gapless phase with six Dirac points. The passing of x through x = x c is accompanied by the topological quantum transition corresponding to the change in the topological parameter Q.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Korovushkin M. M., Barabanov A. F.
Заглавие : Stability of the superconducting dx2-y2 phase in high-Tc superconductors with respect to the intersite coulomb repulsion of holes at oxygen
Коллективы : Russian Foundation for Basic Research [16-02-00073, 16-02-00304]; Dynasty Foundation; Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools [SP-1361.2015.1]
Место публикации : JETP Letters. - 2016. - Vol. 103, Is. 6. - P.385-389. - ISSN 0021-3640, DOI 10.1134/S0021364016060114. - ISSN 1090-6487(eISSN)
Примечания : Cited References:28. - This work was supported by the Russian Foundation for Basic Research, project nos. 16-02-00073 and 16-02-00304. The work of D.D.M. and M.M.K. was supported by the Dynasty Foundation and the work of M.M.K. was also supported by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. SP-1361.2015.1).
Предметные рубрики: Hubbard-model
Spin polaron
Density
Аннотация: It has been shown that, because of the two-orbital character of the subsystem of holes located at oxygen sites and the spatial separation of this subsystem from that of spins at copper ions, the superconducting phase in high-Tc superconductors is stable with respect to the strong Coulomb repulsion of holes located at nearestneighbor oxygen sites if the order parameter has the dx2−y2 symmetry. This effect is due to the symmetry characteristics of the Coulomb potential, owing to which the equation determining the Cooper pairing in the dx2−y2 channel does not include this potential.
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