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1.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : The interplay of phonon and magnetic mechanism of pairing in strongly correlated electron system of high-Tc cuprates
Коллективы : International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials, Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting
Место публикации : Seventh International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials and Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting: May 13-16, 2009, Beijing, China. - Ст.S1E0900
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : Magnetic flux trapping in porous high-Tc superconductors
Колич.характеристики :4 с
Место публикации : Phys. C: Supercond. Appl. - 2024. - Vol. 619. - Ст.1354486. - ISSN 09214534 (ISSN), DOI 10.1016/j.physc.2024.1354486. - ISSN 18732143 (eISSN)
Примечания : Cited References: 39
Аннотация: Porosity affects the properties of high-Tc superconductors and can improve their performance by enhancing oxygenation, cryocooling, etc. Among other factors, the presence of pores plays a significant role in the process of magnetic flux trapping. Relationships with the porosity manifest in the irreversibility field, the full penetration field, and the remnant magnetization of the samples. To account for the effect of porosity on the trapped magnetic flux into type-II superconductors, a simple toy model is suggested. Generally, as the porosity increases, the trapped flux and related parameters tend to diminish. However, in the case of microscopic samples, porosity can enhance magnetic flux trapping.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanov D. A., Togushova Y. N., Korshunov M. M.
Заглавие : Changes of the Fermi surface topology in the three-orbital model for iron pnictides with the spin-orbit coupling
Колич.характеристики :9 с
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2023. - Vol. 16, Is. 6. - P.795-803. - ISSN 19971397 (ISSN); Журн. СФУ. Матем. и физ. - ISSN 23136022 (eISSN)
Примечания : Cited References: 28
Аннотация: Effect of the spin-orbit coupling on the band structure and the Fermi surface of the three-orbital model is studied. The inter-orbital part of the model is reformulated to fully conform with the iron lattice symmetry. Because there are two iron ions in the unit cell, we introduce the intra-and inter-ion spin-orbit coupling constants to separate the effect of the related couplings on the band structure and the Fermi surface. Both the intra-and inter-ion parts lift the degeneracy of some bands at the Γ = (0, 0) point and the splitting of bands along the (0, π) ‒ (π, π) direction of the Brillouin zone. We show that the inter-ion part of the spin-orbit coupling leads to the topological change of the Fermi surface — the splitting of two Fermi surface sheets around the M = (π, π) point.Изучено влияние спин-орбитального взаимодействия на зонную структуру и поверхность Ферми в трехорбитальной модели. Межорбитальная часть модели изменена для полного соответствия с симметрией решетки железа. Из-за наличия двух ионов железа в элементарной ячейке мы вводим внутри- и межионную константы спин-орбитального взаимодействия для разделения эффектов соответствующих взаимодействий на зонную структуру и поверхность Ферми. И внутри, и межионная части снимают вырождение некоторых зон в точке Γ = (0, 0) и вырождение вдоль направления (0, π) − (π, π) зоны Бриллюэна. Показано, что межионная часть спин-орбитального взаимодействия приводит к изменению топологии поверхности Ферми, а именно к разделению листов поверхности Ферми вблизи точки M = (π, π).
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : On estimating the critical current density in polycrystalline superconductors synthesized by solid-state method
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 4. - P.1089-1092. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06575-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 38
Аннотация: In a recent paper, Zhang et al. [1] studied the effect of a Pb content on the superconducting properties of Bi-2223. Some earlier, Ramirez et al. [2] explored the effect of compaction pressure on the Bi-2212. In both studies, the critical current densities were estimated and compared for a series of polycrystalline superconducting samples. The synthesis conditions for the highest critical current density were claimed in both works. This comment explains that the average granule size should be used instead of the sample size in the Bean formula for the polycrystalline superconductors synthesized by solid-state, sol–gel, electrospinning, and solution blow spinning methods. The corrected estimations for the commented articles conclude that the synthesis conditions affect both the granule size and the intragranular critical current density. The synthesis parameters for the highest critical current density conditions are clarified.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zlotnikov A. O.
Заглавие : Majorana vortex modes in spin-singlet chiral superconductors with noncollinear spin ordering: Local density of states study
Место публикации : Phys. Rev. B. - 2023. - Vol. 107, Is. 14. - Ст.144513. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.107.144513. - ISSN 24699969 (eISSN)
Примечания : Cited References: 71. - I am grateful for fruitful discussions with participants of the seminar of Laboratory of Theoretical Physics in Kirensky Institute of Physics, especially with V. V. Val'kov, S. V. Aksenov, A. D. Fedoseev, and M. S. Shustin. The reported study was funded by the Theoretical Physics and Mathematics Advancement Foundation “BASIS”
Аннотация: In this study, topologically nontrivial edge and vortex bound states are described in the coexistence phase of chiral spin-singlet superconductivity and noncollinear spin ordering on a triangular lattice in the presence of few (up to four) vortices. We consider the topological phase transition induced by the magnetic order between the phase hosting Majorana modes and the initial phase of the chiral d-wave superconductivity supporting non-Majorana modes which is also topologically nontrivial. The change of the excitation spectrum at the critical point is obtained in both cases of open and periodic boundary conditions in the presence of vortices. It is proved that zero-energy Majorana modes localized at vortex cores are caused by noncollinear long-range magnetic ordering. Even though nearby excitation energies of subgap states including the edge-localized and vortex-localized states are very close to each other, the energy difference between different vortex bound states is an order of magnitude higher. This difference determines the energy gap for Majorana vortex modes separating them from other vortex bound states. It is found that even in the presence of noncollinear spin ordering its value can be estimated from the excitation energy of vortex bound states in the pure chiral d-wave state for the nonmagnetic case. By studying local density of states near the vortex cores the possibility to experimentally detect the described Majorana vortex modes by scanning tunneling microscopy is discussed. It is demonstrated that Majorana vortex modes and Majorana antivortex modes induced by noncollinear magnetism have different features in energy and spatially resolved density of states due to the chiral symmetry on the superconducting order parameter.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Petrov M. I., Nemtsev I. V., Balaev D. A.
Заглавие : Anisotropy and crystallite misalignment in textured superconductors
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 1. - P.59-65. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06454-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project “Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements” No. 20–42–240008
Аннотация: A misalignment of anisotropic crystallites causes small values of anisotropy and decreases the critical current density of textured polycrystalline superconductors. To relate the crystallite misalignment and out-plane anisotropy, the magnetic properties of the textured Bi2223 polycrystalline superconductor were investigated. A distribution of orientation angles of crystallites was determined using different data: scanning electron microscopy images and hysteresis magnetization loops when an external magnetic field was applied at different angles with respect to the texturing plane of the sample. It was demonstrated that the standard deviation of the distribution and the magnetic disorder angle of crystallites in textured samples can be determined from the magnetization data in perpendicular directions. These data may be either the irreversible magnetization measured for two different orientations of the sample or the simultaneously measured magnetization projections parallel and perpendicular to the magnetic field.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimova A. N., Kashurnikov V. A., Moroz A. N., Gokhfeld D. M.
Заглавие : Trapped field in superconductors with perforations
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [20-21-00085]; ROSATOM [20-21-00085]
Место публикации : J. Supercond. Nov. Magn. - 2022. - Vol. 35, Is. 1. - P.283-290. - ISSN 1557-1939, DOI 10.1007/s10948-021-06067-7. - ISSN 1557-1947(eISSN)
Примечания : Cited References: 35. - The reported study was funded by RFBR and ROSATOM according to the research project No 20-21-00085 (V.A. Kashurnikov, A.N. Moroz)
Предметные рубрики: MAGNETIZATION
BULK
Аннотация: The Monte Carlo method has been used to calculate the trapped magnetic field in superconducting plates with holes. The mechanism of flux pinning on the holes is implemented with special subprocesses added to the algorithm: vortex capture and emission, both occurring on the hole boundaries. Secondary peaks related to the holes emerge on the calculated profiles of the trapped magnetic field. It has been found that these peaks disappear in plates with sufficiently strong pinning or when the computational mesh is coarse (the case corresponding to a low resolution of probes in experiments). The dependence of the trapped field on the hole radius has been analyzed.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Maksimova A. N., Kashurnikov V. A., Moroz A. N.
Заглавие : Optimizing trapped field in superconductors with perforations
Место публикации : Physica C. - 2022. - Vol. 600. - Ст.1354106. - ISSN 0921-4534, DOI 10.1016/j.physc.2022.1354106
Примечания : Cited References: 28. - The reported study was partly funded by RFBR and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project 20-42-240008 (D.M. Gokhfeld) and by RFBR and ROSATOM according to the research project 20-21-00085 (V.A. Kashurnikov, A.N. Moroz)
Аннотация: The use of artificial holes can improve the performance of high-temperature bulk superconductors. We report the results of Monte Carlo simulations of the trapped magnetic flux in superconducting samples with different configurations of perforated holes. Vortex trapping and emission at the hole boundary were modeled to account for flux pinning on the holes. It was found that the trapped flux can reach its maximum value, which does not depend on the number of holes. The dependence of the trapped flux on the diameter and number of holes is explored and described by the suggested relations that account for pinning on the holes and the effective hole area. Recommendations are provided to attain the maximum trapped flux for a fixed number or diameter of holes.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Nemtsev I. V., Yakimov I. S., Balaev D. A.
Заглавие : Magnetic ion substitution and peak effect in YBCO: the strange case of Y1–xGd xBa2Cu3O7–δ
Место публикации : J. Supercond. Novel Magn. - 2022. - Vol. 35, Is. 10. - P.2679-2687. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06317-2
Примечания : Cited References: 50. - This work was supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project “Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements” No. 20-42-240008
Аннотация: We present the results of a study of the superconducting and paramagnetic properties of polycrystalline Y1–xGdxBa2Cu3O7–δ samples. The critical current density and critical temperature of YBCO were weakly decreased by the Gd doping. A peak effect, which is a nonmonotonic dependence of the critical current density on magnetic field, was detected for all samples. The peak position shifted to higher magnetic fields with increasing Gd content. This behavior is opposite to the shift of the peak effect observed for other YBCO compounds doped by magnetic ions. This unusual behavior is apparently related to the realized granular structure instead of the type of doping ion. A correlation between the peak position and the granule size was found in the investigated samples and other polycrystalline YBCO compounds.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aksenov S. V., Fedoseev A. D., Shustin M. S., Zlotnikov A. O.
Заглавие : Effective interactions in higher-order topological superconductors with strong electron correlations
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 2, Sect. I: Magnetism and superconductivity. - Ст.I.P7. - P.164-165. - ISBN 978-5-94469-051-7
Примечания : Cited References: 7. - The study was supported by Russian Science Foundation, project 22-22-20076
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Kuzmichev S. A., Kuzmicheva T. E.
Заглавие : Direct observation of the spin exciton in Andreev spectroscopy of iron-based superconductors
Место публикации : Materials. - 2022. - Vol. 15, Is. 17. - Ст.6120. - ISSN 19961944 (ISSN), DOI 10.3390/ma15176120
Примечания : Cited References: 50. - All authors acknowledge support by the state assignment of the Ministry of Science and Higher Education of the Russian Federation, nos. 0023-2019-0005 and 0287-2021-0035
Аннотация: Quasiparticle excitations provide viable information on the physics of unconventional superconductors. Higgs and Leggett modes are some of the classic examples. Another important bosonic excitation is the spin exciton originating from the sign-changing superconducting gap structure. Here we report a direct observation of the temperature-dependent spin exciton in the Andreev spectra of iron-based superconductors. Combined with the other experimental evidence, our observation confirms the extended s-wave (s±) order parameter symmetry and indirectly proves the spin-fluctuation mechanism of Cooper pairing.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Enhanced s*-wave component of the superconducting gap in overdoped HTSC cuprates with orthorhombic distortion
Место публикации : Phys. Lett. A. - 2022. - Vol. 444. - Ст.128226. - ISSN 03759601 (ISSN), DOI 10.1016/j.physleta.2022.128226
Примечания : Cited References: 67. - We would like to especially thank A. Bianconi for new ideas, useful discussions, and suggestions. The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science according to the research project “Studies of superexchange and electron-phonon interactions in correlated systems as a basis for searching for promising functional materials” No. 20-42-240016
Аннотация: In this work, the concentration and temperature dependence of the superconducting gap of the HTSC cuprate in the orthorhombic phase are obtained within the framework of the Hubbard model taking into account the exchange mechanism of pairing. To elucidate the reasons for the unexpectedly large s*-wave component of the superconducting gap in the overdoped regime, the electronic structure of low-energy excitations and the k-dependent contributions of pair states to the gap components were investigated. It is shown that the s*-wave component growth results from the shallowing of the electron pocket in the region of the s*-wave component maximum.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nekrasov I., Ovchinnikov S. G.
Заглавие : Hydrides under high pressure
Место публикации : J. Supercond. Nov. Magn. - 2022. - Vol. 35, Is. 4: Road to Room Temperature Superconductivity. - P.959-963. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-021-06087-3
Примечания : Cited References: 44. - This work was partially supported by RFBR grant No. 20-02-00011
Аннотация: The experimental discovery of the highest, up to 0 degree Celsius, superconducting transition temperatures Tc in the class of so-called hydrides under high pressure is undoubtedly the striking event in modern physics. In this paper, we give a short overview of the some history of the room-temperature conventional superconductivity. A theoretical description of such high Tc, as was shown and even predicted in a number of ab initio works, can be unambiguously given in the framework of the electron–phonon mechanism of Cooper pairing. Thus, the basic equation to calculate Tc will be the one proposed in 1957 by Bardeen, Cooper, and Schriefer. It is known that in this case the value of Tc is directly determined by a number of effective parameters: the Debye frequency, the density of electronic states at the Fermi level, and the electron–phonon interaction constant. Within the framework of the modern development of the density functional theory, all these quantities can be obtained using standard packages for band structure calculations.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Begunovich L. V., Korshunov M. M.
Заглавие : Band structure of organic-ion-intercalated (EMIM)xFeSe superconductor
Место публикации : Materials. - 2022. - Vol. 15, Is. 5. - Ст.1856. - ISSN 19961944 (ISSN), DOI 10.3390/ma15051856
Примечания : Cited References: 62. - This work was supported in part by Russian Science Foundation (Project 19-73-10015)
Аннотация: The band structure and the Fermi surface of the recently discovered superconductor (EMIM)xFeSe are studied within the density functional theory in the generalized gradient approximation. We show that the bands near the Fermi level are formed primarily by Fe-d orbitals. Although there is no direct contribution of EMIM orbitals to the near-Fermi level states, the presence of organic cations leads to a shift of the chemical potential. It results in the appearance of small electron pockets in the quasi-two-dimensional Fermi surface of (EMIM)xFeSe.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komarov K. K., Dzebisashvili D. M.
Заглавие : The origin of an inflection point on the temperature dependence of the London penetration depth in hole-doped cuprate high-temperature superconductors
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-02-00837, 20-3270059]
Место публикации : J. Exp. Theor. Phys. - 2021. - Vol. 133, Is. 3. - P.351-359. - ISSN 1063-7761, DOI 10.1134/S1063776121080021. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 77. - This work was supported by the Russian Foundation for Basic Research, project nos. 18-02-00837 and 20-3270059
Предметные рубрики: MUON-SPIN-ROTATION
QUASI-PARTICLES
FERMI-SURFACE
Аннотация: A scenario of the formation of an experimentally observed inflection point on the temperature dependence of the London penetration depth λ in cuprate high-temperature superconductors (HTSCs) with optimal hole doping is discussed within the spin-polaron concept. It is shown that the reason for the appearance of an inflection point on the 1/λ2(T) dependence is due to the features of the energy spectrum of spin-polaron quasiparticles in the superconducting phase, as well as to the specific temperature dependence of their spectral density.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Togushova Yu. N., Dolgov, O., V
Заглавие : Decisive proofs of the s± → s++ transition in the temperature dependence of the magnetic penetration depth
Коллективы : Russian Foundation for Basic Research (RFBR)Russian Foundation for Basic Research (RFBR) [19-32-90109]; RFBRRussian Foundation for Basic Research (RFBR); Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science to the Research Projects 'Electronic correlation effects and multiorbital physics in iron-based materials and cuprates' [19-42-240007]
Место публикации : Supercond. Sci. Technol. - 2021. - Vol. 34, Is. 7. - Ст.075008. - ISSN 0953-2048, DOI 10.1088/1361-6668/abff6f. - ISSN 1361-6668(eISSN)
Примечания : Cited References: 40. - We are grateful to D V Efremov, A S Fedorov, S G Ovchinnikov, E I Shneyder, D Torsello, and A N Yaresko for useful discussions. This work was supported in part by the Russian Foundation for Basic Research (RFBR) Grant No. 19-32-90109 and by RFBR and Government of Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science to the Research Projects 'Electronic correlation effects and multiorbital physics in iron-based materials and cuprates' Grant No. 19-42-240007.
Предметные рубрики: ORDER-PARAMETER
IMPURITIES
SUPERCONDUCTORS
STATES
MODEL
Аннотация: One of the features of the unconventional s± state in iron-based superconductors is possibility to transform to the s++ state with the increase of the nonmagnetic disorder. Detection of such a transition would prove the existence of the s± state. Here we study the temperature dependence of the London magnetic penetration depth within the two-band model for the s± and s++ superconductors. By solving Eliashberg equations accounting for the spin-fluctuation mediated pairing and nonmagnetic impurities in the T-matrix approximation, we have derived a set of specific signatures of the s± → s++ transition: (1) sharp change in the behavior of the penetration depth λL as a function of the impurity scattering rate at low temperatures; (2) before the transition, the slope of ΔλL(T) = λL(T) - λL(0) increases as a function of temperature, and after the transition this value decreases; (3) the sharp jump in the inverse square of the penetration depth as a function of the impurity scattering rate, λL-2(Γa), at the transition; (4) change from the single-gap behavior in the vicinity of the transition to the two-gap behavior upon increase of the impurity scattering rate in the superfluid density ρs(T).
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Terentyev K. Yu., Yakimov I. S., Balaev D. A.
Заглавие : Interplay of magnetic and superconducting subsystems in Ho-doped YBCO
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR); Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project "Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements" [20-42-240008]
Место публикации : J. Supercond. Nov. Magn. - 2021. - Vol. 34. Is. 10. - P.2537-2543. - ISSN 1557-1939, DOI 10.1007/s10948-021-05954-3. - ISSN 1557-1947(eISSN)
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project "Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements" No. 20-42-240008
Предметные рубрики: TEMPERATURE
TRANSPORT
PEAK
DY
SUSCEPTIBILITY
TRANSITION
BEHAVIOR
Аннотация: Superconducting and paramagnetic contributions to the magnetization of polycrystalline Y1−xHoxBa2Cu3O7−δ samples were investigated. The superconductivity is responsible for a partial screening of magnetic ions from an external magnetic field and for a possible sinking of antiferromagnetic correlations between these ions. Magnetic moments of Ho ions influence on a peak effect induced by the order–disorder transition of the Abrikosov vortex lattice. The critical current density and the critical temperature of YBCO are not changed by the Ho doping.
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18.

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

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Komarov K. K., Dzebisashvili D. M.
Заглавие : On the origin of the inflection point in the temperature dependence of the london penetration depth in cuprate superconductors
Коллективы : International Conference on Supercondactivity and Magnetism
Место публикации : International conference on supercondactivity and magnetism (ICSM2021): abstract book. - 2021. - P.75
Примечания : Cited References: 5
Материалы конференции,
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Semenov S. V., Balaev D. A., Petrov M. I.
Заглавие : Universal behavior and temperature evolution of the magnetoresistance hysteresis in granular high-temperature superconductors Y-Ba-Cu-O
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 7. - P.1069-1080. - ISSN 1063-7834, DOI 10.1134/S1063783421070192. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 80. - The authors are grateful to D.M. Gokhfeld for discussion of the results. The measurements of the transport properties were performed in part on a PPMS-6000 system of the Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences
Предметные рубрики: CRITICAL-CURRENT-DENSITY
CURRENT-VOLTAGE CHARACTERISTICS
MAGNETIC-FLUX COMPRESSION
Аннотация: Regularities in the behavior of the magnetoresistance hysteresis R(H) in the granular yttrium high-temperature superconductors (HTSs) have been established. For this purpose, a comparative analysis of the magnetotransport properties has been carried out on the granular HTS samples, which exhibit (i) approximately the same magnetic properties and temperatures of the onset of the superconducting transition (90.5–93.5 K, which is characteristic of HTS grains) and (ii) different critical transport currents JC (which is characteristic of grain boundaries). Despite a significant (by more than an order of magnitude) spread of the JC values for the three samples, a universal behavior of the magnetoresistance hysteresis has been found, which is apparently inherent in all the granular Y–Ba–Cu–O compounds. The R(H) hysteresis is extremely broad and, in a fairly wide external field range, the dependence of the magnetoresistance hysteresis width ΔН on the field Hdec (the external field for the decreasing hysteresis branch is Н = Hdec) is almost linear: ΔH ≈ Hdec. This behavior is observed over the entire temperature range of implementation of the superconducting state (the investigations have been carried out at temperatures of 77–88 and 4.2 K). The result obtained has been explained by considering the effective field in grain boundaries, which is a superposition of the external field and the field induced by the magnetic moments of grains. The field induced by grains, in turn, significantly increases in the region of grain boundaries due to the magnetic flux compression (the grain boundary length is shorter than the HTS grain size by several orders of magnitude). The aforesaid has been confirmed by the analysis of the R(H) hysteresis for the Y–Ba–Cu–O- and CuO-based HTS composite, in which the grain boundary length is purposefully increased; as a result, the flux compression is less pronounced and the R(H) hysteresis narrows.
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