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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : SANDALOV I. S., RICHTER M.
Заглавие : FLUX PHASE, NEEL ANTIFERROMAGNETISM, AND SUPERCONDUCTIVITY IN THE T-J MODEL
Разночтения заглавия :авие SCOPUS: Flux phase, Neel antiferromagnetism, and superconductivity in the t-J model
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1994. - Vol. 50, Is. 17. - P12855-12865. - ISSN 0163-1829, DOI 10.1103/PhysRevB.50.12855
Примечания : Cited References: 27
Предметные рубрики: HUBBARD-MODEL
INSTABILITY
ELECTRONS
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Dimer state in the two-dimensional anisotropic alternated-exchange Heisenberg model
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1998. - Vol. 40, Is. 6. - P986-990. - ISSN 1063-7834, DOI 10.1134/1.1130463
Примечания : Cited References: 14
Предметные рубрики: SPIN-PEIERLS
HUBBARD-MODEL
SUPERCONDUCTIVITY
ANTIFERROMAGNETS
Аннотация: An analysis is made of the two-dimensional Heisenberg model with S = 1/2, anisotropic exchange interaction between nearest neighbors, and alternating exchange in two directions, [100] and [010] (corresponding to condensation of the (pi,pi) mode) and in one direction [100] (corresponding to condensation of the (pi,0) mode), The quantum Monte Carlo method is used to calculate the thermodynamic characteristics and the spin correlation functions which are used as the basis to determine the boundary of stability of an anisotropic antiferromagnetic with respect to alternation of exchange delta = (1 - J(x,y) / J(z))(0.4) in the (pi,pi) model and delta = (1 - J(x,y) / J(z))(0.31) in the (pi,0) model. In the (pi,0) model a disordered quantum state exists in the range (1 - J(x,y) / J(z))(0.31) delta (0.3-0.35). The energy (E - 0.68)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Ovchinnikov S. G., Baklanov I. O.
Заглавие : Comparison of superconductivity in Sr2RuO4 and copper oxides
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2000. - Vol. 61, Is. 22. - P15392-15397. - ISSN 1098-0121, DOI 10.1103/PhysRevB.61.15392
Примечания : Cited References: 21
Предметные рубрики: T-J MODEL
HUBBARD-MODEL
LAYERED PEROVSKITE
ELECTRONS
Аннотация: To compare the superconductivity in strongly correlated electron systems with the antiferrornagnetic fluctuations in the copper oxides and with the ferromagnetic fluctuations in Sr2RuO4 a t-J-l model is proposed. The antiferromagnetic coupling J results in the superconducting state of d(x2-y2) symmetry and the ferromagnetic coupling I results in the spin-triplet p-type state. The difference in the gap anisotropies provides the large difference in T-c values, for the typical values of the coupling constants: T-c similar to 1 K for the ruthenste and T-c similar to 100 K for the cuprates.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Ovchinnikov S. G., Baklanov I. O., Goryachev E. G.
Заглавие : Microscopic model of the coexistence of superconductivity and ferromagnetism in the hybrid ruthenate-cuprate oxide RuSr2GdCu2O8
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2000. - Vol. 91, Is. 2. - P353-360. - ISSN 1063-7761, DOI 10.1134/1.1311995
Примечания : Cited References: 37
Предметные рубрики: T-J MODEL
HUBBARD-MODEL
LAYERED PEROVSKITE
SR2RUO4
ELECTRONS
COPPER
SPECTRUM
Аннотация: A microscopic t-J-I model with competing antiferromagnetic (J) and ferromagnetic (I) exchange interactions is proposed for strongly correlated electrons in RuSr2GdCu2O8 . It is assumed that J much greater than I for CuO2 layers and J much less than I for RuO2 layers. A superconducting solution of d(x2-y2) symmetry was obtained for the CuO2 layers while competition between ferromagnetism and p-type triplet superconducting pairing is obtained for RuO2 layers. It is shown that the RuO2 layers have a lower carrier concentration in the Hubbard subband formed by coupled ((d(xy)-p)-pi) orbitals compared with a bulk Sr2RuO4 crystal, which leads to stabilization of the ferromagnetic state in the RuO2 layer. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Kuz'min E. V., Ovchinnikov S. G.
Заглавие : Electronic structure and order parameter symmetry in high-temperature superconductors
Место публикации : Uspekhi Fiz. Nauk: MEZHDUNARODNAYA KNIGA, 2000. - Vol. 170, Is. 2. - P.189-192. - ISSN 0042-1294
Примечания : Cited References: 31
Предметные рубрики: CORRELATED ELECTRONS
HUBBARD-MODEL
OXIDES
LA2-XSRXCUO4
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Comparison of electronic structure, magnetic mechanism, and symmetry of pairing in ruthenates and cuprates
Место публикации : Ruthenate and rutheno-cuprate materials: unconventional superconductivity, magnetism and quantum phase transitions. Ser. lecture notes in physics: Springer Verlag, 2002. - Vol. 603: International Conference on Ruthenate and Rutheno-Cuprate Materials (OCT 25-27, 2001, VIETRI SUL MARE, ITALY). - P.239-255. - ISBN 0075-8450. - ISBN 3-540-44275-8
Примечания : Cited References: 48
Предметные рубрики: METAL-INSULATOR-TRANSITION
SUPERCONDUCTOR SR2RUO4
LAYERED PEROVSKITE
BAND-STRUCTURE
CORRELATED ELECTRONS
MOTT TRANSITION
COPPER OXIDES
HUBBARD-MODEL
RUSR2GDCU2O8
CA2-XSRXRUO4
Аннотация: A generalized tight-binding (GTB) method is developed to calculate quasi-particle band structure with explicit account for strong electronic correlations. The GTB method combines exact diagonalization of the multi-orbital P-d model Hamiltonian within the unit cell and the perturbation theory in the Hubbard X-operators form for the inter-cell hopping and interactions. For undoped cuprates we obtain the valence band structure in excellent agreement with ARPES data, evolution of the band structure with doping with an in-gap state at small doping, impurity-like band at higher doping to optimally doped metal. The effective low-energy Hamiltonian has the form of singlet-triplet t-J model. For ruthenates the t-J-I model is proposed with both antiferromagnetic J and ferromagnetic I couplings. In the strong correlation limit, the mean-field theory of superconductivity results in d-wave singlet pairing mediated by J (cuprates) and p-wave triplet one mediated by I (ruthenates) with ratio T-c((d))/T-c((p)) similar to 100 due to the different symmetry of the gap. The competition of ferromagnetic and antiferromagnetic order in rutheno-cuprates is also discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : Generalization of Luttinger's theorem for strongly correlated electron systems
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 8. - P1415-1422. - ISSN 1063-7834, DOI 10.1134/1.1602872
Примечания : Cited References: 19. - The authors are grateful to V.V. Val’kov for helpful remarks. This work was supported by the INTAS (grant no. INTAS-01-0654), the Russian Foundation for Basic Research and the Krasnoyarsk KraÏ Science Foundation (program “EniseÏ,” project no. 02-02-97705), the program of the Russian Academy of Sciences “Quantum Macrophysics,” and the Russian Academy of Sciences, Siberian Division (Lavrent’yev Contest for Youth Projects)
Предметные рубрики: NARROW ENERGY BANDS
HUBBARD-MODEL
FERMI-SURFACE
LATTICE
Аннотация: By on the analyzing the general structure of the Green function of a strongly correlated electron system, it is shown that, for the regime of strong correlations, Luttinger's theorem should be generalized in the following way: the volume of the Fermi surface of the system of noninteracting particles is equal to that of the quasiparticles in the strongly correlated system with due regard for the spectral weight of the quasiparticles. An investigation of the t-J model and of the Hubbard model, as applied to the paramagnetic nonsuperconducting phase, shows that the generalized Luttinger theorem is valid for these models. (C) 2003 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-T-c copper oxides
Разночтения заглавия :авие SCOPUS: Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-T c copper oxides
Место публикации : Eur. Phys. J. B: SPRINGER, 2007. - Vol. 57, Is. 3. - P271-278. - ISSN 1434-6028, DOI 10.1140/epjb/e2007-00179-2
Примечания : Cited References: 49
Предметные рубрики: ELECTRON CORRELATIONS
HUBBARD-MODEL
RANGE-ORDER
DIMENSIONS
WAVE
FERMIONS
SYSTEMS
BANDS
METAL
Ключевые слова (''Своб.индексиров.''): doping dependent evolution--kinematic correlation functions--low energy excitations--quantum phase transitions--doping (additives)--electric excitation--mean field theory--parameter estimation--phase transitions--quantum theory--copper oxides
Аннотация: In this paper a mean-field theory for the spin-liquid paramagnetic non-superconducting phase of the p- and n-type high-T-c cuprates is developed. This theory applied to the effective t-t'-t ''-J* model with the ab initio calculated parameters and with the three-site correlated hoppings. The static spin-spin and kinematic correlation functions beyond Hubbard-I approximation are calculated self-consistently. The evolution of the Fermi surface and band dispersion is obtained for the wide range of doping concentrations x. For p-type systems the three different types of behavior are found and the transitions between these types are accompanied by the changes in the Fermi surface topology. Thus a quantum phase transitions take place at x = 0.15 and at x = 0.23.Due to the different Fermi surface topology we found for n-type cuprates only one quantum critical concentration, x = 0.2. The calculated doping dependence of the nodal Fermi velocity and the effective mass are in good agreement with the experimental data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I., Shorikov A., Anisimov V. I., Renner M., Brenig W.
Заглавие : Itinerant in-plane magnetic fluctuations and many-body correlations in NaxCoO2
Разночтения заглавия :авие SCOPUS: Itinerant in-plane magnetic fluctuations and many-body correlations in Nax Co O2
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2007. - Vol. 75, Is. 9. - Ст.94511. - ISSN 1098-0121, DOI 10.1103/PhysRevB.75.094511
Примечания : Cited References: 47
Предметные рубрики: TRANSITION-METALS
WAVE-FUNCTIONS
HUBBARD-MODEL
FERMI-SURFACE
ENERGY-BANDS
FERROMAGNETISM
APPROXIMATION
DIMENSIONS
SYSTEMS
FIELD
Аннотация: Based on the ab initio band structure for NaxCoO2, we derive the single-electron energies and the effective tight-binding description for the t(2g) bands using projection procedure. Due to the presence of the next-nearest-neighbor hoppings, a local minimum in the electronic dispersion close to the Gamma point of the first Brillouin zone forms. Correspondingly, in addition to a large Fermi surface, an electron pocket close to the Gamma point emerges at high doping concentrations. The latter yields a scattering channel, resulting in a peak structure of the itinerant magnetic susceptibility at small momenta. This indicates dominant itinerant in-plane ferromagnetic fluctuations above a certain critical concentration x(m), in agreement with neutron scattering data. Below x(m), the magnetic susceptibility shows a tendency toward the antiferromagnetic fluctuations. We further analyze the many-body effects on the electronic and magnetic excitations using various approximations applicable for different U/t ratios.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Kokorina E. E., Pchelkina Z. V.
Заглавие : Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: the LDA + GTB approach
Разночтения заглавия :авие SCOPUS: Dominance of many-body effects over the one-electron mechanism for band structure doping dependence in Nd2-xCexCuO4: The LDA+GTB approach
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2007. - Vol. 19, Is. 48. - Ст.486203. - ISSN 0953-8984, DOI 10.1088/0953-8984/19/48/486203
Примечания : Cited References: 36
Предметные рубрики: NARROW ENERGY BANDS
HUBBARD-MODEL
SUPERCONDUCTORS
DENSITY
TEMPERATURE
ORBITALS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--band structure--correlation methods--crystal structure--local density approximation--superconducting materials--electronic correlations--fermionic quasiparticles--neodymium compounds
Аннотация: In the present work we report band structure calculations for the high-temperature superconductor Nd2-xCexCuO4 in the regime of strong electronic correlations within an LDA + GTB method, which combines the local density approximation (LDA) and the generalized tight-binding method (GTB). The two mechanisms of band structure doping dependence were taken into account. Namely, the one-electron mechanism provided by the doping dependence of the crystal structure, and the many-body mechanism provided by the strong renormalization of the fermionic quasiparticles due to the large on-site Coulomb repulsion. We have shown that, in the antiferromagnetic and in the strongly correlated paramagnetic phases of the underdoped cuprates, the main contribution to the doping evolution of the band structure and Fermi surface comes from the many-body mechanism.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Ovchinnikov S. G.
Заглавие : Isotope effect in the model of strongly correlated electrons with the magnetic and phonon superconducting pairing mechanisms
Коллективы : Presidium of the Russian Academy of Sciences [40]; Russian Academy of Sciences; Russian Foundation for Basic Research [09-02-00127]
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.1017-1021. - ISSN 1063-7761, DOI 10.1134/S1063776109120139
Примечания : Cited References: 42. - This study was financed under programs 5.7 and "Quantum Physics of Condensed Matter" of the Presidium of the Russian Academy of Sciences, integration project no. 40 of the Siberian Branch and Ural Division of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: CUPRATE SUPERCONDUCTORS
PHASE-TRANSITIONS
3-CENTER INTERACTIONS
HUBBARD-MODEL
TEMPERATURE
LA2-XSRXCUO4
SYMMETRY
EXCHANGE
COPPER
BI2SR2CACU2O8+DELTA
Ключевые слова (''Своб.индексиров.''): ab initio calculations--calculated values--cooper pairing--isotope effect--magnetic mechanisms--order of magnitude--pairing mechanism--phonon mechanism--strongly correlated electrons--superconducting pairing mechanism--superconducting state--type theory--carrier mobility--electron-phonon interactions--isotopes--superconductivity--superconducting magnets
Аннотация: Peculiarities of the temperature isotope effect in a BCS-type theory describing the exchange and phonon mechanisms of Cooper pairing in a system of strongly correlated electrons are considered. The electron-phonon interaction constant is determined from the fitting of the calculated value of the isotope-effect index to the observed value with the parameters of La(2 - x) Sr (x) CuO(4) obtained from ab initio calculations. The value of this constant indicates that the contribution from the traditional pairing mechanism to the superconducting state is of the same order of magnitude as the contribution from the magnetic mechanism.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : Radiation damages under irradiation of the BCS superconductor MgB2 by high-energy electrons
Разночтения заглавия :авие SCOPUS: Spatial structure of superconducting correlations of dx2 - y2 symmetry in high-temperature superconductors
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 2. - P242-244. - ISSN 1063-7834, DOI 10.1134/S1063783411020235
Примечания : Cited References: 14. - This study was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Siberian Branch and Ural Branch of the Russian Academy of Sciences ( project no. 40), and the Ministry of Education and Science ( project no. MK-1683.2010.2 and the Federal Target Program "Kadry" no. NK-589P).
Предметные рубрики: HUBBARD-MODEL
Аннотация: The spatial structure of the correlation function of the order parameter of the symmetry has been investigated within the t-J model in the generalized mean field approximation taking into account the "no-double occupancy" constraint due to strong electron correlations. A slow decay of the correlation function to the thirtieth coordination sphere has been found. The limitation by pairing of only the nearest neighbors makes it possible to take into account less than 17% of the superconducting correlations.
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13.

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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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Mitskan V. A., Korovushkin M. M.
Заглавие : Kohn-Luttinger superconductivity in monolayer and bilayer semimetals with the Dirac spectrum
Коллективы : RAS Division of Physical Sciences [II.3.1], Russian Foundation for BasicResearch [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. 119, Is. 6. - P.1140-1149. - ISSN 1063, DOI 10.1134/S1063776114120048. - ISSN 10906509(eISSN)
Примечания : Cited References:70. - This work was performed under the Program of the RAS Division ofPhysical Sciences (project no. II.3.1) and was supported financially bythe Russian Foundation for Basic Research (project nos. 14-02-00058 and14-02-31237) and by the President of the Russian Federation (grant no.MK-526.2013.2). One of the authors (M.M.K.) thanks the "Dynasty"foundation for financial support.
Предметные рубрики: FERMI-SURFACE
REPULSIVE INTERACTIONS
DOPED GRAPHENE
HUBBARD-MODEL
Аннотация: The effect of Coulomb interaction in an ensemble of Dirac fermions on the formation of superconducting pairing in monolayer and bilayer doped graphene is studied using the Kohn-Luttinger mechanism disregarding the Van der Waals potential of the substrate and impurities. The electronic structure of graphene is described using the Shubin-Vonsovsky model taking into account the intratomic, interatomic, and interlayer (in the case of bilayer graphene) Coulomb interactions between electrons. The Cooper instability is determined by solving the Bethe-Saltpeter integral equation. The renormalized scattering amplitude is obtained with allowance for the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction. It plays the role of effective interaction in the Bethe-Salpeter integral equation. It is shown that the allowance for the Kohn-Luttinger renormalizations as well as intersite Coulomb interaction noticeably affects the competition between the superconducting phases with the f-wave and d + id-wave symmetries of the order parameter. It is demonstrated that the superconducting transition temperature for an idealized graphene bilayer with significant interlayer Coulomb interaction between electrons is noticeably higher than in the monolayer case.
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15.

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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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Mitskan V. A., Korovushkin M. M.
Заглавие : Phase diagram of the Kohn-Luttinger superconducting state for bilayer graphene
Место публикации : Eur. Phys. J. B: Springer, 2015. - Vol. 88, Is. 6. - Ст.157. - ISSN 1434, DOI 10.1140/epjb/e2015-60198-x. - ISSN 14346036(eISSN)
Примечания : Cited References:60. - The authors are grateful to V.V. Val'kov for valuable remarks. This work is supported by the Russian Foundation for Basic Research (Projects Nos. 14-02-00058 and 14-02-31237). One of the authors (M.Yu.K.) gratefully acknowledges support from the Basic Research Program of the National Research University Higher School of Economics. Another one (M.M.K.) thanks the scholarship SP-1361.2015.1 of the President of the Russian Federation and the Dynasty foundation.
Предметные рубрики: REPULSIVE INTERACTIONS
DOPED GRAPHENE
HUBBARD-MODEL
FERMI-SURFACE
Аннотация: The effect of Coulomb interaction between Dirac fermions on the formation of the Kohn-Luttinger superconducting state in bilayer doped graphene is studied disregarding of the effect of the van der Waals potential of the substrate and impurities. The phase diagram determining the boundaries of superconductive domains with different types of symmetry of the order parameter is built using the extended Hubbard model in the Born weak-coupling approximation with allowance for the intratomic, interatomic, and interlayer Coulomb interactions between electrons. It is shown that the Kohn-Luttinger polarization contributions up to the second order of perturbation theory in the Coulomb interaction inclusively and an account for the long-range intraplane Coulomb interactions significantly affect the competition between the superconducting phases with the f-, p + ip-, and d + id-wave symmetries of the order parameter. It is demonstrated that the account for the interlayer Coulomb interaction enhances the critical temperature of the transition to the superconducting phase.
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17.

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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : Microscopic derivation of the Ginzburg-Landau equations for the periodic Anderson model in the coexistence phase of superconductivity and antiferromagnetism
Коллективы : Russian Foundation for Basic Research [13-02-00523]; regional Grant Siberia [15-42-04372]; RF Presidential Grant [SP-1370.2015.5]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.439-445. - ISSN 0022-2291, DOI 10.1007/s10909-015-1410-y. - ISSN 1573-7357(eISSN)
Примечания : Cited References:11. - This work was supported in part by the Russian Foundation for Basic Research, Grant No. 13-02-00523 and regional Grant Siberia No. 15-42-04372. A.O.Z. acknowledges the support of RF Presidential Grant No. SP-1370.2015.5.
Предметные рубрики: HUBBARD-MODEL
Ключевые слова (''Своб.индексиров.''): ginzburg-landau equations--superconductivity--antiferromagnetism--coexistence phase--periodic anderson model
Аннотация: On the basis of the periodic Anderson model, the microscopic Ginzburg-Landau equations for heavy-fermion superconductors in the coexistence phase of superconductivity and antiferromagnetism have been derived. The obtained expressions are valid in the vicinity of quantum critical point of heavy-fermion superconductors when the onset temperatures of antiferromagnetism and superconductivity are sufficiently close to each other. It is shown that the formation of antiferromagnetic ordering causes a decrease of the critical temperature of superconducting transition and order parameter in the phase of coexisting superconductivity and antiferromagnetism.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Mitskan V. A., Korovushkin M. M.
Заглавие : High-Tc and Low-Tc superconductivity in electron systems with repulsion
Коллективы : Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Basic Research Program of the National Research University Higher School of Economics; Dynasty foundation; [SP-1361.2015.1]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1043-1048. - ISSN 1557-1939, DOI 10.1007/s10948-016-3384-7. - ISSN 1557-1947(eISSN)
Примечания : Cited References:31. - The authors are grateful to V. V. Val'kov, I. S. Burmistrov, M. V. Feigel'man, and A. Ya. Tzalenchuk for valuable remarks. This work is supported by the Russian Foundation for Basic Research (nos. 14-02-00058 and 14-02-31237). One of the authors (M. Yu. K.) gratefully acknowledges support from the Basic Research Program of the National Research University Higher School of Economics. Another one (M. M. K.) thanks the scholarship SP-1361.2015.1 of the President of Russia and the Dynasty foundation.
Предметные рубрики: Fermion systems
Doped graphene
Hubbard-model
Phase-diagram
Superfluidity
Density
Ключевые слова (''Своб.индексиров.''): unconventional superconductivity--kohn-luttinger mechanism--graphene
Аннотация: We demonstrate the instability of the normal state of purely repulsive fermionic systems towards the transition to the Kohn-Luttinger superconducting state. We construct the superconducting phase diagrams of these systems in the framework of the Hubbard and Shubin-Vonsovsky models on the square and hexagonal lattices. We show that an account for the long-range Coulomb interactions, as well as the Kohn- Luttinger renormalizations, lead to an increase in the critical superconducting temperatures in various materials, such as high-temperature superconductors, idealized monolayer, and bilayer of doped graphene. Additionally, we discuss the role of the structural disorder and the nonmagnetic impurities in superconducting properties of real graphene systems.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz’min V. I., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Influence of varying magnetic order in an external magnetic field on the electronic structure and Fermi surface within the t–J model
Место публикации : JETP Letters. - 2016. - Vol. 103, Is. 2. - P.125-130. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364016020089
Примечания : Cited References: 46. - This work was supported by the Russian Science Foundation (project no. 14-12-00061).
Предметные рубрики: C copper oxides
Quantum oscillations
Cuprate superconductors
Hubbard-model
Temperature
Excitations
YBa2Cu3OY
Evolution
Phase
Аннотация: We investigate the electronic structure of the two-dimensional t–J model in a transverse external static magnetic field with canted long-range magnetic order using cluster perturbation theory. The distribution of the spectral weight in the whole range of fields from zero to ferromagnetic saturation is explored. We demonstrate the possibility of a sharp change in a distribution of spectral weight at the Fermi level associated with the magnetic correlations when varying magnetic field.
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