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 1-10    11-18 
1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M.Yu., Mitskan V. A., Korovushkin M. M.
Заглавие : Effect of the long-range Coulomb interaction on the phase diagram of the Kohn–Luttinger superconducting state in Idealized graphene
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2015. - Vol. - P.1-7. - ISSN 0022, DOI 10.1007/s10909-015-1427-2. - ISSN 15737357(eISSN)
Ключевые слова (''Своб.индексиров.''): unconventional superconductivity--kohn-luttinger mechanism--graphene monolayer
Аннотация: The effect of the long-range Coulomb interaction on the formation of the Kohn–Luttinger superconductivity in monolayer doped graphene is studied disregarding the Van der Waals potential of the substrate and both magnetic and non-magnetic impurities. It is shown that the allowance for the Kohn–Luttinger renormalizations up to the second order in perturbation theory in the on-site Hubbard interaction inclusively, as well as in the intersite Coulomb interaction, significantly affects the interplay between the superconducting phases with the f-wave, p+ip-wave, and d+id-wave symmetries of the order parameter. It is demonstrated that taking Coulomb repulsion of electrons located at the next-nearest neighboring atoms in such a system into account changes qualitatively the phase diagram and enhances the critical temperature of the transition to the superconducting phase.
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2.

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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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hirschfeld P. J., Korshunov M. M., Mazin I. I.
Заглавие : Gap symmetry and structure of Fe-based superconductors
Место публикации : Rep. Prog. Phys.: IOP PUBLISHING LTD, 2011. - Vol. 74, Is. 12. - Ст.124508. - ISSN 0034-4885, DOI 10.1088/0034-4885/74/12/124508
Примечания : Cited References: 312. - Wewould like to thankRArita, A V Chubukov, T P Devereaux, O Dolgov, I Eremin, R M Fernandes, S Graser, H Ikeda, A F Kemper, H Kontani, K Kuroki, T A Maier, Y Matsuda, V Mishra, K A Moler, R Prozorov, DJ Scalapino, T Shibauchi, G R Stewart, I Vekhter, W Wang, Y Wang and H-H Wen for useful discussions. Partial support was provided by DOE DE-FG02-05ER46236 (PJH and MMFK) and NSF-DMR-1005625 (PJH). MMK acknowledges support from RFBR (grant 09-02-00127), Presidium of RAS program 'Quantum physics of condensed matter' N5.7, FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK P891 and GK 16.740.12.0731), and President of Russia (grant MK-1683.2010.2). PJH and MMK are grateful for the support of the Kavli Institute for Theoretical Physics and the Stanford Institute for Materials and Energy Science during the writing of this work.
Предметные рубрики: D-WAVE SUPERCONDUCTORS
DENSITY-OF-STATES
HIGH-TEMPERATURE SUPERCONDUCTIVITY
RESOLVED PHOTOEMISSION-SPECTROSCOPY
IRON-BASED SUPERCONDUCTORS
UNCONVENTIONAL SUPERCONDUCTORS
ANISOTROPIC SUPERCONDUCTORS
RENORMALIZATION-GROUP
PAIRING SYMMETRY
CUPRATE SUPERCONDUCTORS
Аннотация: The recently discovered Fe-pnictide and chalcogenide superconductors display low-temperature properties suggesting superconducting gap structures which appear to vary substantially from family to family, and even within families as a function of doping or pressure. We propose that this apparent nonuniversality can actually be understood by considering the predictions of spin fluctuation theory and accounting for the peculiar electronic structure of these systems, coupled with the likely 'sign-changing s-wave' (s(+/-)) symmetry. We review theoretical aspects, materials properties and experimental evidence relevant to this suggestion, and discuss which further measurements would be useful to settle these issues.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I.
Заглавие : Dynamical magnetic susceptibility in the lamellar cobaltate superconductor NaxCoO2 center dot yH(2)O
Разночтения заглавия :авие SCOPUS: Dynamical magnetic susceptibility in the lamellar cobaltate superconductor Nax Co O2 y H2 O
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2008. - Vol. 77, Is. 6. - Ст.64510. - ISSN 1098-0121, DOI 10.1103/PhysRevB.77.064510
Примечания : Cited References: 49
Предметные рубрики: UNCONVENTIONAL SUPERCONDUCTIVITY
NMR
Аннотация: We systematically analyze the influence of the superconducting gap symmetry and the electronic structure on the dynamical spin susceptibility in superconducting NaxCoO2 center dot yH(2)O within three different models: The single a(1g)-band model with nearest-neighbor hoppings, the realistic three-band t(2g) model with, and without e(g)' pockets present at the Fermi surface. We show that the magnetic response in the normal state is dominated by the incommensurate antiferromagnetic spin density wave fluctuations at large momenta in agreement with experimental temperature dependence of the spin-lattice relaxation rate. Also, we demonstrate that the presence or the absence of the e(g)' pockets at the Fermi surface does not significantly affect this conclusion. In the superconducting state our results for d(x)(2)-y(2)- or d(xy)-wave symmetries of the superconducting order parameter are consistent with experimental data and exclude nodeless d(x)(2)-y(2)+id(xy)-wave symmetry. We further point out that the spin-resonance peak proposed earlier is improbable for the realistic band structure of NaxCoO2 center dot yH(2)O. Moreover, even if present the resonance peak is confined to the antiferromagnetic wave vector and disappears away from it.
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5.

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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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Dolgov O. V., Korshunov M. M., Golubov A. A., Efremov D. V.
Заглавие : Does magnetic scattering always suppress superconducting transition?
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.I2.5. - P.125. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : We acknowledge partial support by RFBR (Grant RFBR 16-02-00098)
Ключевые слова (''Своб.индексиров.''): unconventional superconductivity--impurities, pnictides --multiband systems
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7.

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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8.

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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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shestakov V. A., Korshunov M. M., Togushova Yu.N., Efremov D. V., Dolgov O. V.
Заглавие : Details of the disorder-induced transition between s± and s++ states in the two-band model for Fe-based superconductors
Коллективы : Russian Foundation for Basic Research [16-02-00098]; Government Support of the Leading Scientific Schools of the Russian Federation [NSh-7559.2016.2]; 'BASIS' Foundation for Development of Theoretical Physics and Mathematics
Место публикации : Supercond. Sci. Technol. - 2018. - Vol. 31, Is. 3. - Ст.034001. - ISSN 0953-2048, DOI 10.1088/1361-6668/aaa501. - ISSN 1361-6668(eISSN)
Примечания : Cited References:62. - We are grateful to P D Grigor'ev and M V Sadovskii for useful discussions. This work was supported in part by the Russian Foundation for Basic Research (grant 16-02-00098) and Government Support of the Leading Scientific Schools of the Russian Federation (NSh-7559.2016.2). MMK and VAS acknowledge the support of the 'BASIS' Foundation for Development of Theoretical Physics and Mathematics.
Предметные рубрики: IRON-BASED SUPERCONDUCTORS
HIGH-TEMPERATURE SUPERCONDUCTIVITY
PAIRING
Ключевые слова (''Своб.индексиров.''): unconventional superconductors--iron pnictides--iron chalcogenides--impurity scattering
Аннотация: IIrradiation of superconductors with different particles is one of many ways to investigate the effects of disorder. Here we study the disorder-induced transition between s ± and s ++ states in the two-band model for Fe-based superconductors with nonmagnetic impurities. Specifically, we investigate the important question of whether the superconducting gaps during the transition change smoothly or abruptly. We show that the behavior can be of either type and is controlled by the ratio of intraband to interband impurity scattering potentials, and by a parameter σ, that represents scattering strength and ranges from zero (Born approximation) to one (unitary limit). For the pure interband scattering potential and the scattering strength σ ≲ 0.11, the s ± → s ++ transition is accompanied by steep changes in the gaps, while for larger values of σ, the gaps change smoothly. The behavior of the gaps is characterized by steep changes at low temperatures, T˂ 0.1Tc0 with Tc0 being the critical temperature in the clean limit, otherwise it changes gradually. The critical temperature Tc is always a smooth function of the scattering rate in spite of the steep changes in the behavior of the gaps.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Korshunov M. M.
Заглавие : Itinerant spin fluctuations in iron-based superconductors
Место публикации : Perturbation theory: advances in research and applications. - New York: Nova Science Publishers, 2018. - Chap. 2. - P.61-137. - ISBN 9781536129908. - ISBN 9781536129892
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin fluctuations--spin resonance peak--unconventional superconductivity
Аннотация: In multiband systems, it is possible to explore a variety of competing ground states. Bright examples are the Fe-based pnictides and chalcogenides, which demonstrate metallic, superconducting, and various magnetic phases. Here I discuss only one of the many interesting topics, namely, spin fluctuations in metallic multiband systems. I show how to calculate the effect of itinerant spin excitations on the electronic properties and formulate a theory of spin fluctuation-induced superconductivity. The superconducting state is unconventional and thus the system demonstrates unusual spin response with the spin resonance feature. I discuss its origin, consequences, and relation to experimental observations. Role of the spin-orbit coupling is specifically emphasized.
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