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1.

Вид документа : Однотомное издание
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Shneyder E. I.
Заглавие : Lifshitz quantum phase transitions and Fermi surface transformation with hole doping in high-Tc superconductors
Место публикации : arXiv. - 2009. - Ст.arXiv:0909.2308
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Balaev D. A., Yakimov I. S., Petrov M. I., Semenov S. V.
Заглавие : Tuning the peak effect in the Y1−xNdxBa2Cu3O7−δ compound
Место публикации : Ceram. Int.: Elsevier, 2017. - Vol. 43, Is. 13. - P.9985-9991. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2017.05.011
Примечания : Cited References: 37. - This work was supported by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project no. 16-48-243018 and the Russian Foundation for Basic Research, project no. 16-38-00400.
Ключевые слова (''Своб.индексиров.''): peak effect--bulk superconductors--critical current--pinning--characterization--ybco
Аннотация: Polycrystalline Y1−xNdxBa2Cu3O7−δ (x=0.02, 0.11, and 0.25) superconductors are synthesized. Nd atoms are uniformly distributed over grains. The magnetization loops of the samples have a pronounced second peak in a wide temperature range. The magnetization data are analyzed using the extended critical state model. It is found that the order-disorder transition of the vortex lattice is affected by doping with neodymium and temperature; the second-peak field and width decrease monotonically with increasing x value. The undoped polycrystalline YBa2Cu3O7−δ compound is assumed to exhibit the peak effect in higher magnetic fields.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Generalized Kondo lattice model and its spin-polaron realization by the projection method for cuprates
Коллективы : Russian Foundation for Basic Research [16-02-00073, 16-02-00304, 16-42-240435]; Siberian Branch of the Russian Academy of Sciences (Complex Program) [II.2P, 0358-2015-0005]
Место публикации : Theor. Math. Phys.: MAIK Nauka-Interperiodica / Springer, 2017. - Vol. 191, Is. 2. - P.752-763. - ISSN 0040-5779, DOI 10.1134/S0040577917050142. - ISSN 1573-9333(eISSN)
Примечания : Cited References:35. - This research was supported by the Russian Foundation for Basic Research (Grant No. 16-02-00073, 16-02-00304, and 16-42-240435) and the Siberian Branch of the Russian Academy of Sciences (Complex Program No. II.2P, Grant No. 0358-2015-0005).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
HIGH-TC SUPERCONDUCTORS
COPPER OXIDES
Ключевые слова (''Своб.индексиров.''): strong electron correlation--spin-fermion model--kondo lattice model--spin polaron
Аннотация: The spin-fermion model, which is an effective low-energy realization of the three-band Emery model after passing to the Wannier representation for the px and py orbitals of the subsystem of oxygen ions, reduces to the generalized Kondo lattice model. A specific feature of this model is the existence of spin-correlated hoppings of the current carriers between distant cells. Numerical calculations of the spectrum of spin-electron excitations highlight the important role of the long-range spin-correlated hoppings.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Togushova Yu.N., Dolgov O. V.
Заглавие : Impurities in multiband superconductors
Место публикации : Physics-Uspekhi: Turpion, 2016. - Vol. 59, Is. 12. - P.1211-1240. - ISSN 10637869 (ISSN), DOI 10.3367/UFNe.2016.07.037863
Примечания : Cited References: 200. - We acknowledge partial support by RFBR (grant 16-02-00098) and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2).
Ключевые слова (''Своб.индексиров.''): unconventional superconductors--iron pnictides--iron chalcogenides--impurity scattering
Аннотация: Disorder impurities and defects violating the ideal long-range order is always present in solids. It can result in interesting and sometimes unexpected effects in multiband superconductors, especially if the superconductivity is uncon-ventional, thus having symmetry other than the usual s-wave. This paper uses the examples of iron-based pnictides and chal-cogenides to examine how both nonmagnetic and magnetic impurities affect superconducting states with s± and s++ order parameters. We show that disorder causes the transition between s± and s++ states and examine what observable effects this transition can produce. © 2016 Uspekhi Fizicheskikh Nauk, Russian Academy of Sciences.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Balaev D. A., Yakimov I. S., Dubrovskiy A. A., Terentyev K. Yu., Freydman A. L., Krasikov A. A., Petrov M. I.
Заглавие : Establishing of peak effect in YBCO by Nd substitution
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН , Russian Foundation for Basic Research [16-38-00400]
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440. - P.127-128. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.089. - ISSN 1873-4766(eISSN)
Примечания : Cited References:10. - The work was supported by Russian Foundation for Basic Research Grant No. 16-38-00400.
Предметные рубрики: SUPERCONDUCTORS
Ключевые слова (''Своб.индексиров.''): peak effect--magnetization--bulk superconductors--critical current--ybco--nd3+
Аннотация: Y0.75Nd0.25Ba2Cu3O7−d superconductor has the peak effect with pronounced fishtail feature on magnetization hysteresis. The magnetic field of the peak effect maximum is in ~4 times higher than one of NdBa2Cu3O7−d. The magnetization hysteresis is tilted anticlockwise due to paramagnetic Nd3+ ions occurred on the surface of grains and in the vortex cores.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Shestakov V. A., Togushova, Yu. N.
Заглавие : Comparison of experimental data on the spin resonance frequency and gap magnitudes in Fe-based superconductors
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН , RFBR [16-02-00098]; Government Support of the Leading Scientific Schools of the Russian Federation [NSh-7559.2016.2]
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440: EURO-Asian Symposium on Trends in Magnetism (EASTMAG) (AUG 15-19, 2016, Siberian Fed Univ, Krasnoyarsk, RUSSIA). - P.133-135. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.082. - ISSN 1873-4766(eISSN)
Примечания : Cited References:73. - We would like to thank H. Kontani, S.A. Kuzmichev, T.E. Kuzmicheva, and V.M. Pudalov for useful discussions. We acknowledge partial support by RFBR (Grant 16-02-00098), and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2).
Предметные рубрики: RESOLVED PHOTOEMISSION-SPECTROSCOPY
INELASTIC NEUTRON-SCATTERING
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--inelastic neutron scattering--unconventional--superconductivity--magnetic mechanism of pairing
Аннотация: Here we review experimental data on the peak in inelastic neutron scattering (INS) and superconducting gaps extracted from various experimental techniques. Comparison of energy scales gives the confidence that the observed peak in INS for most materials is the true spin resonance.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Semenov S. V., Balaev D. A., Pochekutov M. A., Velikanov D. A.
Заглавие : Anisotropy of the magnetoresistive properties of granular high-temperature superconductors resulting from magnetic flux compression in the intergrain medium
Место публикации : Phys. Solid State: Maik Nauka-Interperiodica Publishing, 2017. - Vol. 59, Is. 7. - P.1291-1297. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783417070241
Примечания : Cited References: 26
Аннотация: To elucidate the origin of the well-known anisotropy of the magnetoresistive properties of granular high-temperature superconductors (HTSs), which is related to the mutual orientation of magnetic field H and transport current j, we investigate the hysteretic dependences of magnetoresistance R(H) of the yttrium HTS sample at the perpendicular (H ⊥ j) and parallel (H || j) configurations. The hysteretic R(H) dependences are analyzed using the concept of the effective field in the intergrain boundaries through which superconducting current carriers tunnel. The effective degree of magnetic flux compression in the intergrain medium at the perpendicular configuration was found to be twice as much as at the parallel one. This approach explains well the anisotropy of the magnetoresistive properties of granular HTSs, which was previously reported by many authors, and the temperature dependences of the resistance in the resistive transition region.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Koblischka M. R., Gokhfeld D. M., Chang C., Hauet T., Hartmann U.
Заглавие : Pinning force scaling of electrospun Bi-2212 nanowire networks
Место публикации : Solid State Commun.: Elsevier, 2017. - Vol. 264. - P.16-18. - ISSN 00381098 (ISSN), DOI 10.1016/j.ssc.2017.07.002
Примечания : Cited References: 24. - This work is supported by the DFG project Ko2323/8, which is gratefully acknowledged
Ключевые слова (''Своб.индексиров.''): electrospinning--bi-2212 superconductors--flux pinning--pinning force scaling
Аннотация: Flux pinning forces were determined on different network samples of superconducting Bi2Sr2CaCu2O8 (Bi-2212) nanowires prepared by the electrospinning technique. We employed magnetization data determined by SQUID magnetometry in a wide temperature range 10 K T 35 K, where a strong superconducting signal prevails. The scaling analysis of the pinning forces was applied to interprete the data obtained. Both pure and Li-doped Bi2212 nanowire networks exhibit a peak position of h0∼ 0.11, which is smaller than the expected value of h0
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Togushova, Yu. N., Shestakov V. A., Korshunov M. M.
Заглавие : Impurity-induced smearing of the spin resonance peak in Fe-based superconductors
Коллективы : RFBR [13-02-01395]; President Grant for Government Support of the Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; Ministry of education and science of Russia [GF-2, SFU]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.481-487. - ISSN 0022-2291, DOI 10.1007/s10909-016-1577-x. - ISSN 1573-7357(eISSN)
Примечания : Cited References:25. - We acknowledge partial support by the RFBR (Grant 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), and The Ministry of education and science of Russia (GF-2, SFU).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
ELECTRONIC-STRUCTURE
IRON
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin resonance peak--spin-orbit coupling--impurity scattering
Аннотация: The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Effect of canted antiferromagnetic order on the electronic structure in the t–J* model within the cluster perturbation theory
Место публикации : J. Exp. Theor. Phys.: Maik Nauka-Interperiodica Publishing, 2016. - Vol. 123, Is. 3. - P.511-519. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776116090065
Примечания : Cited References: 50. - We are grateful to V.V. Val’kov for stimulating discussions. This work was supported by the Russian Science Foundation (project no. 14-12-00061)
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--electronic structure--high temperature superconductors--magnetic fields--antiferromagnetic orderings--cluster perturbation theories--electron-doping--external fields--external magnetic field--non-monotonic dependence--short-range correlations--spectral weight--perturbation techniques
Аннотация: The electronic structure in the two-dimensional t–J* model with canted antiferromagnetic order in an external magnetic field has been calculated within the cluster perturbation theory. In zero external field, the evolution of the Fermi surface with n-type doping has been obtained in good agreement with experimental data on cuprate superconductors. It has been shown that the inclusion of short-range correlations can result in a nonmonotonic dependence of the spectral weight distribution at the Fermi level on the external magnetic field. In contrast to the case of electron doping, such changes in the case of hole doping can be expected at experimentally achievable fields. © 2016, Pleiades Publishing, Inc.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Korshunov M. M., Nikolaev S. V., Togushova Yu. N.
Заглавие : Cluster perturbation approach to iron-based superconductors
Коллективы : Quantum in Complex Matter: Superconductivity, Magnetism and Ferroelectricity, International conference
Место публикации : Quant. in Complex Matter: Supercond., Magnet. and Ferroelectr.: book of abstracts/ ed. A. Bianconi. - Rome, 2016. - P.148. - ISBN 978-88-6683-055-9
Примечания : References: 8. - This work was partially supported by the RFBR (grant 16-02-00098)
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Мягков, Виктор Григорьевич, Быкова, Людмила Евгеньевна, Жигалов, Виктор Степанович, Середкин, Виталий Александрович, Турпанов, Игорь Александрович, Юшков, Василий Иванович, Патрин, Геннадий Семёнович, Тамбасов, Игорь Анатольевич, Мацынин, Алексей Александрович, Рыбакова, Александра Николаевна, Великанов, Дмитрий Анатольевич, Бондаренко, Галина Николаевна
Заглавие : Why in cuprate superconductors the d-wave superconductivity emerges rather than s-wave
Коллективы : Южный федеральный университет, "Порядок, беспорядок и свойства оксидов", международный междисциплинарный симпозиум, "Order, Disorder and Properties of Oxides", International interdisciplinary seminar
Место публикации : 19-й Междунар. симп. "Порядок, беспорядок и свойства оксидов" (ODPO-19): труды симпозиума. - 2016. - Вып. 19, Т. 1. - С. 48-49
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Spin-polaron nature of fermion quasiparticles and their d-wave pairing in cuprate superconductors
Место публикации : JETP Letters. - 2016. - Vol. 104, Is. 10. - P.730-741. - ISSN 00213640 (ISSN), DOI 10.1134/S002136401622015X
Примечания : Cited References: 52
Аннотация: In the framework of the spin-fermion model, to which the Emery model is reduced in the limit of strong electron correlations, it is shown that the fermion quasiparticles in cuprate high-Tcsuperconductors (HTSCs) arise under a strong effect of exchange coupling between oxygen holes and spins of copper ions. This underlies the spin-polaron nature of fermion quasiparticles in cuprate HTSCs. The Cooper instability with respect to the d-wave symmetry of the order parameter is revealed for an ensemble of such quasiparticles. For the normal phase, the spin-polaron concept allows us to reproduce the fine details in the evolution of the Fermi surface with the changes in the doping level x observed in experiment for La2-xSrxCuO4. The calculated T–x phase diagram correlates well with the available experimental data for cuprate HTSCs. © 2016, Pleiades Publishing, Inc. All Right Reserved.
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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 : Stability of the d-wave pairing with respect to the intersite Coulomb repulsion in cuprate superconductors
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440. - P.123-126. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.090
Примечания : Cited References: 23. - The work was supported by the Siberian Branch of Russian Academy of Sciences (project no. 0358-2015-0002, Complex Program II.2P), the Russian Foundation for Basic Research (RFBR) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (projects nos. 16-42-240435 and 16-42-243057). The work of A.F.B. was funded by RFBR (project no. 16-02-00304). The work of M.M.K. was supported by grant of the President of the Russian Federation (project MK-1398.2017.2).
Предметные рубрики: HUBBARD-MODEL
EXCITATIONS
Ключевые слова (''Своб.индексиров.''): cuprate superconductors--spin-fermion model--intersite coulomb repulsion
Аннотация: Within the spin-fermion model for cuprate superconductors, the influence of the intersite Coulomb interactions V2 and V′2V′2 between holes located at the next-nearest-neighbor oxygen ions of CuO2 plane on the implementation of the dx2−y2dx2−y2-wave pairing is studied. It is shown that d-wave pairing can be suppressed only for unphysically large values of V2 and V′2V′2.В рамках спин-фермионной модели для купратных сверхпроводников изучено влияние межузельных кулоновских отталкиваний V2 и V2' между дырками, находящимися на следующих за ближайшими ионах кислорода CuO2-плоскости, на реализацию сверхпроводящего dx2y2-спаривания. Показано, что d-спаривание подавляется только при нефизически больших значениях параметров V2 и V2'.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nikolaev S. V., Korshunov M. M.
Заглавие : Spin and charge susceptibilities of the two-orbital model within the cluster perturbation theory for Fe-based materials
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 12. - P.3093-3097. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-016-3784-8
Примечания : Cited References: 40. - We acknowledge partial support by RFBR (grants 12-02-31534, 13-02-01395, and 16-02-00098), and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2).
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--mutiorbital models--cluster perturbation theory
Аннотация: Cluster perturbation theory is used to calculate band structure, spectral functions, Fermi surface, and spin and charge susceptibilities for the two-orbital model of iron pnictides with the on-site multiorbital Hubbard interactions. Susceptibilities are calculated within the approximation combining the cluster perturbation theory for the self-energy corrections and the random-phase approximation (RPA) for the vertex renormalizations. Calculations for the small values of Hubbard repulsion U ≤ 2 eV confirm that the rigid band approximation and RPA for the spin and charge susceptibilities are suitable approaches for the case of weak interactions. © 2016, Springer Science+Business Media New York.
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16.

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 d-wave pairing toward the intersite Coulomb repulsion in CuO2 plane
Место публикации : J. Low Temp. Phys. - 2018. - Vol. 191, Is. 5-6. - P.408-425. - ISSN 00222291 (ISSN), DOI 10.1007/s10909-018-1882-7
Примечания : Cited References: 70. - Acknowledgements The work was supported by the program of the Presidium of the Russian Academy of Sciences No. 12 “Fundamental problems of high-temperature superconductivity”, the Russian Foundation for Basic Research (RFBR) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (Projects Nos. 16-42-243057 and 16-42-240435). The work of A. F. B. was funded by RFBR (Project No. 16-02-00304). The work of M. M. K. was supported by a grant of the President of the Russian Federation (Project MK-1398.2017.2).
Ключевые слова (''Своб.индексиров.''): cuprate superconductors--unconventional superconductivity--spin-charge coupling--spin polarons--intersite coulomb interaction
Аннотация: Taking into account the real crystalline structure of the CuO2 plane and the strong spin-fermion coupling, we study the influence of the intersite Coulomb repulsion between holes on the Cooper instability of the spin-polaron quasiparticles in cuprate superconductors. The analysis shows that only the superconducting d-wave pairing is implemented in the whole region of doping, whereas the solutions of the self-consistent equations for the s-wave pairing are absent. It is shown that intersite Coulomb interaction V1 between the holes located at the nearest oxygen ions does not affect the d-wave pairing, because its Fourier transform Vq vanishes in the kernel of the corresponding integral equation. The intersite Coulomb interaction V2 of quasiparticles located at the next-nearest oxygen ions does not vanish in the integral equations, however, but it is also shown that the d-wave pairing is robust toward this interaction for physically reasonable values of V2.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Hierarchy of low-energy models of the electronic structure of cuprate HTSCs: The role of long-range spin-correlated hops
Коллективы : Russian fund for fundamental science, Government of the Krasnoyarsk region, Krasnoyarsk regional fund for scientific and technical activity [16-42-240435]; complex program SO RAN [P.2.P, 0356-2015-0405]; RFFI [16-02-00304]
Место публикации : Low Temp. Phys. - 2018. - Vol. 44, Is. 2. - P.130-138. - ISSN 1063-777X, DOI 10.1063/1.5020908. - ISSN 1090-6517(eISSN)
Примечания : Cited References: 42. - This study was conducted with financial support from the Russian fund for fundamental science, Government of the Krasnoyarsk region, Krasnoyarsk regional fund for scientific and technical activity in the framework of Project No. 16-42-240435 as well as the complex program SO RAN No. P.2.P (Project No. 0356-2015-0405). The work of A. F. Barabanov is supported by RFFI (Grant No. 16-02-00304).
Предметные рубрики: HIGH-TC SUPERCONDUCTORS
SINGLE-BAND MODELS
OXIDE SUPERCONDUCTORS
Аннотация: It is shown that for the three-band Emery p–d-model that reflects the real structure of the CuO2-plane of high-temperature superconductors in the regime of strong electron correlations, it is possible to carry out a sequence of reductions to the effective models reproducing low-energy features of elementary excitation spectrum and revealing the spin-polaron nature of the Fermi quasiparticles. The first reduction leads to the spin-fermion model in which the subsystem of spin moments, coupled by the exchange interaction and localized on copper ions, strongly interacts with oxygen holes. The second reduction deals with the transformation from the spin-fermion model to the φ–d-exchange model. An important feature of this transformation is the large energy of the φ–d-exchange coupling, which leads to the formation of spin polarons. The use of this fact allows us to carry out the third reduction, resulting in the t̃ −J̃∗−I-model. Its distinctive feature is the importance of spin-correlated hops as compared to the role of such processes in the commonly used t–J*-model derived from the Hubbard model. Based on the comparative analysis of the spectrum of Fermi excitations calculated for the obtained effective models of the CuO2-plane of high-temperature superconductors, the important role of the usually ignored long-range spin-correlated hops is determined.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Terent'ev K. Yu., Gokhfeld D. M., Savitskaya N. E., Popkov S. I., Petrov M. I.
Заглавие : Superconductivity on interfaces of nonsuperconducting granules La2CuO4 and La1.56Sr0.44CuO4
Место публикации : J. Supercond. Nov. Magn. - 2018. - Vol. 31, Is. 12. - P.3867–3874. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-018-4668-x
Примечания : Cited References: 19. - The authors are grateful to D.A. Balaev for fruitful discussions, and I.V. Nemtsev for electronic microscope measurements in the center for shared use, KSC SB RAS. The work is supported by the Russian Science Foundation (project No. 17-72-10067).
Ключевые слова (''Своб.индексиров.''): magnetic properties--superconductivity--oxide superconductors--grain boundaries--lco--lsco--josephson media
Аннотация: Composite materials fabricated by annealing of nonsuperconducting ceramics La2CuO4 and La1.56Sr0.44CuO4 at 910 °C during various time are investigated. Areas of superconducting La1.85Sr0.15CuO4 phase arises at boundaries of contacting nonsuperconducting granules. The volume fraction of the superconducting phase increases with increasing annealing time. A model describing the magnetic and transport properties of the samples at low magnetic fields is constructed. The magnetotransport characteristics of obtained samples at low magnetic fields (∼ 100 Oe) are defined by weak links network formed by superconducting areas. At high fields, behavior of the system is defined by a magnetization of the disconnected superconducting islands. The average size of the superconducting areas has been estimated from an extended critical state model.
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19.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : Magnetization of polycrystalline high-Tc superconductors
Место публикации : High-temperature superconductors: occurrence, synthesis and applications. - New York: Nova Science Publishers, 2018. - P.181-194. - ISBN 9781536133424. - ISBN 9781536133417
Примечания : Cited References: 29
Ключевые слова (''Своб.индексиров.''): critical current--magnetization--pinning force--scaling--surface
Аннотация: Magnetization loops of polycrystalline high-Tc superconductors always are semireversible; they have some asymmetry relative to field axis. These magnetization loops are described successfully by the extended critical state model, which accounts the equilibrium magnetization of the grain surface. The model is applied to determine the intragranular critical current density, the depth of the equilibrium surface region and the grain size from magnetic measurements. The dependence of the critical current density on the magnetic field, the pinning force scaling, the full penetration field and the irreversibility field are discussed.Асимметричные петли намагниченности высокотемпературных сверхпроводников успешно описываются расширенной моделью критического состояния. Внутригранульная плотность критического тока, глубина приповерхностного слоя с равновесной намагниченностью и размер гранул могут быть получены из магнитных измерений.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Togushova Yu.N.
Заглавие : Band structure modification due to the spin-orbit coupling in the three-orbital model for iron pnictides
Коллективы : Russian Foundation for Basic Research [16-02-00098]; BASIS Foundation for Development of Theoretical Physics and Mathematics
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2018. - Vol. 11, Is. 4. - P.430-437. - ISSN 1997-1397, DOI 10.17516/1997-1397-2018-11-4-430-437; Журн. СФУ. Сер. "Математика и физика". - ISSN 2313-6022(eISSN)
Примечания : Cited References: 14. - This work was supported in part by the Russian Foundation for Basic Research (grant 16-02-00098) and BASIS Foundation for Development of Theoretical Physics and Mathematics.
Предметные рубрики: SUPERCONDUCTING STATE
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin-orbit coupling--band structure--fermi surface--сверхпроводники на основе железа--спин-орбитальное взаимодействие--зонная структура--поверхность ферми
Аннотация: We study the effect of the spin-orbit coupling on the band structure and the Fermi surface of the three-orbital model within the two-iron Brillouin zone. Due to the presence of two irons in the crystallographically correct unit cell, the spin-orbit coupling can be divided into the intra- and intercell parts with respect to the one-iron unit cell. We show that the intercell part produces the reconstruction of the Fermi surface in the form of the pronounced splitting between the previously degenerate electron (π, π)-pockets along the (0, π) - (π, π) direction. Intracell part shifts the bands around (0, 0) point and removes degeneracy there. There are also some other band shifts but they should not affect the low-energy physics because they occur at energy scales of about 1 eV below the Fermi level.Исследовано влияние спин-орбитального взаимодействия на зонную сруктуру и поверхность Ферми трехорбитальной модели в зоне Бриллюэна двух атомов железа на ячейку. Из-за присутствия двух атомов железа в кристаллографической элементарной ячейке спин-орбитальное взаимодействие можно разделить на внутри- и межъячеечную части по отношению к элементарной ячейке решетки железа. Показано, что межъячеечная часть приводит к реконструкции поверхности Ферми в виде выраженного расщепления между ранее вырожденными электронными карманами в точке (π ;π ) вдоль направления (0; π) − (π; π). Внутриячеечная часть приводит к сдвигу зон вблизи точки (0; 0) и снимает там вырождение. Также имеют место другие сдвиги зон, но они не должны влиять на низкоэнергетическую физику, поскольку возникают на энергиях порядка 1 eV ниже уровня Ферми.
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