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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Shneyder E. I., Kozlov P. A., Ovchinnikov S. G.
Заглавие : Transition between large and small polaron states in the electronic structure of HTSC cuprates
Коллективы : RFBR [13-02-01395 a, 14-02-31677 mol_a]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1063-1068. - ISSN 1557-1939, DOI 10.1007/s10948-016-3375-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:10. - This work was funded by RFBR according to the research projects No. 13-02-01395 a and No. 14-02-31677 mol_a.
Предметные рубрики: SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): cuprates--strong electron correlations--electron-phonon interaction--polaron--franck-condon process--hubbard fermions--band structure
Аннотация: The effect of strong electron correlations (SEC) and strong electron-phonon interaction (EPI) on the electronic structure of cuprates is studied within the polaronic version of the generalized tight binding method. Both diagonal and off-diagonal EPI in terms of ionic coordinates are considered.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Kozlov P. A., Makarov I. A., Ovchinnikov S. G.
Заглавие : Transition Between Large and Small Polaron States in the Electronic Structure of HTSC Cuprates
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.P2.11. - P.153. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 3
Ключевые слова (''Своб.индексиров.''): cuprates--strong electron correlations--electron-phonon interaction--polaron--franck-condon
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Yakimov L. Y.
Заглавие : The exact spectrum of Fermi quasiparticles in Kondo-Anderson ferromagnetic lattice
Разночтения заглавия :авие SCOPUS: The Exact Spectrum of Fermi Quasiparticles in Kondo-Anderson Ferromagnetic Lattice
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 8. - P1479-1483. - ISSN 1063-7834, DOI 10.1134/1.1602883
Примечания : Cited References: 8. - This work was supported by the federal program “Integration” (project no. B 0017) and the Russian Foundation for Basic Research (project no. 02-02-97705)
Предметные рубрики: MAGNETIC POLARON
Аннотация: The spectrum of Fermi excitations of a nondegenerate ferromagnetic semiconductor at T=0 with one electron present is investigated in order to describe the electronic structure of manganites with inclusion of strong electron correlations within the Anderson periodic model with s-d exchange interaction. Exact dispersion relations and the Green functions for different spin projections are found. The density-of-states function is calculated for different positions of the d level relative to the band bottom. (C) 2003 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shklyaev A. A., Barabanov A. F.
Заглавие : The effect of spin correlations on a superconducting phase of the spin polarons in 2D Kondo lattice
Место публикации : J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 1. - ISSN 17426588 (ISSN), DOI 10.1088/1742-6596/200/1/012217
Ключевые слова (''Своб.индексиров.''): antiferromagnets--concentration dependence--cuprates--experimental data--hopping integrals--kondo lattice model--kondo lattices--magnetic correlation--spin correlations--spin polaron--superconducting phase--superconducting phase transitions--temperature dependence--copper compounds--correlators--magnetism--phase diagrams--polarons--superconducting magnets--superconductivity--phase transitions
Аннотация: The effect of the magnetic correlators on the spin polaron superconducting phase is studied in terms of 2D Kondo lattice model. It is shown that hopping integrals are renormalized by the magnetic correlators and as a result the Tc phase diagram is changing significantly. By computation the effect of magnetic correlation functions on the concentration dependence of T c was analysed and their substantial role in description of doped antiferromagnets is demonstrated. The obtained phase diagram is in qualitative agreement with experimental data for temperature dependence of the superconducting phase transition with d-type symmetry in cuprates. © 2010 IOP Publishing Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Romanova O. B., Sitnikov M. N., Kretinin V. V., Galyas, A., I, Yanushkevich, K., I
Заглавие : The alternating-sign magnetoresistance of polycrystalline manganese chalcogenide films
Коллективы : Russian Foundation for Basic Research (RFBR) [18-52-00009 Bel_a, 18-32-00079 mol_a, 18-42-240001 r_a]; [3.5743.2017/6.7]
Место публикации : Semicond. Sci. Technol. - 2018. - Vol. 33, Is. 8. - Ст.085006. - ISSN 0268-1242, DOI 10.1088/1361-6641/aace44. - ISSN 1361-6641(eISSN)
Примечания : Cited References: 33. - The reported study was funded by Russian Foundation for Basic Research (RFBR) according to the research project No 18-52-00009 Bel_a; No 18-32-00079 mol_a; No 18-42-240001 r_a; the state order No 3.5743.2017/6.7.
Предметные рубрики: NEUTRON-SCATTERING
SURFACE-STATES
MNTE
CONDUCTIVITY
MECHANISM
Ключевые слова (''Своб.индексиров.''): polycrystalline films--magnetoresistance--impedance--polaron--magnetic--properties--thermoelectric
Аннотация: The correlation between the dc and ac electrical resistance and the structural, magnetic, and thermoelectric properties of polycrystalline MnSe1−X Te Х (0.3 ≤ X ≤ 0.4) manganese chalcogenide films in the temperature range of 80–400 K has been investigated. Inhomogeneous electronic states and transitions between them accompanied by structural lattice deformations have been found at temperatures including the Neel temperature region. The magnetic susceptibility maximum above the Neel temperature in a magnetic field of 8.6 kOe has been observed. Temperature ranges of the coexistence of two types of electrically inhomogeneous states have been established by impedance spectroscopy in the frequency range of 0.1–1000 kHz and the change of the hopping conductivity for diffusion one accompanied by the magnetic susceptibility minimum has been found. The magnetoresistance in magnetic fields of up to 12 kОе has been established. It has been revealed that the thermopower and magnetoresistance change its sign upon heating. The experimental data are explained using a spin polaron model with the localization of polarons and formation of the electron phase-separation. The alternation of magnetoresistance in sign is attributed to the ferromagnetic orbital ordering of electrons and the negative magnetoresistance is explained by suppression of spin fluctuations in a magnetic field.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Zakharova E. V.
Заглавие : Temperature evolution of spin-polaron in-gap states in undoped antiferromagnetic cuprates
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 8. - P1401-1406. - ISSN 1063-7834, DOI 10.1134/S1063783408080027
Примечания : Cited References: 26. - This work was supported by the Russian Foundation for Basic Research (project nos. 06-02-16100 and 0602- 90537-BNTS), the Presidium of the Russian Academy of Sciences (program "Quantum Macrophysics"), and INTAS (YS grant no. 05-109-4891).
Предметные рубрики: J MODEL
LA2-XSRXCUO4
SUPERCONDUCTORS
BAND
Аннотация: The temperature evolution of in-gap states created by the spin polaron effect and located within the gap with charge transfer between the valence and conduction bands is studied for the case of strong electron correlations using the t-t'-t ''-J model of antiferromagnetic undoped cuprates. The effect of temperature is taken into account by temperature renormalization of the magnon concentration, which is calculated using the Heisenberg model with inclusion of weak interlayer exchange and weak in-plane spin anisotropy, and by introducing a Lorentzian with a temperature-dependent half-width in the form corresponding to the marginal Fermi liquid model. With increasing temperature, the spectral weight of the in-gap state, which is proportional to the magnon concentration, grows leading to an increased intensity of the corresponding peak of the spectral function in all points of the Brillouin zone. At points (pi/2, pi/2) and (pi, 0), the main peak is approached by the satellite peak related to the in-gap band and, at points (0, 0) and (pi, pi), the peaks move away from each other.
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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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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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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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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Borisov A. A., Gavrichkov V. A., Korshunov M. M.
Заглавие : Prediction of the in-gap states above the top of the valence band in undoped insulating cuprates due to the spin-polaron effect
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2004. - Vol. 16, Is. 8. - PL93-L100. - ISSN 0953-8984, DOI 10.1088/0953-8984/16/8/L04
Примечания : Cited References: 25
Предметные рубрики: ELECTRONIC-STRUCTURE
LA2-XSRXCUO4
MODEL
ANTIFERROMAGNETISM
SPECTRA
OXIDES
Ключевые слова (''Своб.индексиров.''): quasiparticle band structure--spin-polaron effect--antiferromagnetic materials--approximation theory--doping (additives)--electronic structure--hamiltonians--insulation--magnetic fields--strontium compounds--thermal effects--lanthanum compounds
Аннотация: In the framework of the generalized tight binding method we have calculated the quasiparticle band structure and the spectral functions of the undoped cuprates such as La2CuO4, Sr2CUO2Cl2 etc. Due to spin fluctuations the in-gap state appears above the top of the valence band in the undoped antiferromagnetic insulator similar to in-gap states induced by hole doping. In the ARPES experiments the in-gap states can be detected as weak low energy satellites.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Nikolaev S. V., Zotova M. V., Kaldin R. A., Ovchinnikov S. G.
Заглавие : Polaron transformations in the realistic model of the strongly correlated electron system
Коллективы : Russian Foundation for Basic Research, Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science [18-42-240017, 19-42240007]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 23. - Ст.235114. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.235114. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 69. - We acknowledge the stimulating discussions with V. A. Gavrichkov, G. Seibold, and K. I. Kugel. 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 "Features of electron-phonon coupling in high-temperature superconductors with strong electronic correlations" No. 18-42-240017 and project "Electronic correlation effects and multiorbital physics in iron-based materials and cuprates" No. 19-42240007.
Предметные рубрики: ANOMALOUS-DISPERSION
PHONON INTERACTION
PHASE-TRANSITIONS
LO PHONONS
Аннотация: Electron-phonon coupling, diagonal in a real space formulation, leads to a polaron paradigm of smoothly varying properties. However, fundamental changes, namely the singular behavior of polarons, occur if off-diagonal pairing is involved into consideration. The study of polaron transformations and related properties of matter is of particular interest for realistic models, since competition between diagonal and off-diagonal electron-phonon contributions in the presence of other strong interactions can result in unconventional behavior of the system. Here we consider a two-dimensional multiband pd model of cuprate superconductors with electron-phonon interaction and analyze the features of the systems that are caused by the competition of diagonal and off-diagonal electron-phonon contributions in the limit of strong electron correlations. Using the polaronic version of the generalized tight-binding method, we describe the evolution of the band structure, Fermi surface, density of states at Fermi level, and phonon spectral function in the space of electron-phonon parameters ranging from weak to strong coupling strength of the adiabatic limit. On the phase diagram of polaron properties we reveal two quantum phase transitions and show how electron-phonon interaction gives rise to Fermi surface transformation (i) from hole pockets to true Fermi arcs and (ii) from hole to electron type of conductivity. We also demonstrate the emergence of new states in the phonon spectral function of the polaron and discuss their origin.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Orlov Yu. S., Dudnikov V. A.
Заглавие : Polaron model of a pseudogap state in quasi-one-dimensional systems
Место публикации : J. Exp. Theor. Phys. - 2017. - Vol. 125, Is. 5. - P.798-809. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776117110103
Примечания : Cited References: 57. - This work was supported by the Russian Foundation for Basic Research (project nos. 17-02-00826, 16-02-00507, 16-02-00098, and 16-02-00273), by the Government of the Krasnoyarsk krai, by the Kras-noyarsk Regional Foundation for Supporting Scientific and Technological Activity (project nos. 16-42-243048, 16-42-240746, and 16-43-240505)), and by the Grants Council of the President of the Russian Federation (project nos. SP-1844.2016.1 and NSh-7559.2016.2).
Ключевые слова (''Своб.индексиров.''): basic concepts--cluster perturbation theories--polaron models--pseudogap state--quasi-one dimensional--quasi-one-dimensional systems
Аннотация: A brief overview of the basic concepts and problems of the physics of quasi-one-dimensional (q1D) compounds is given. A consistent theoretical description of the nature of the so-called pseudogap state still remains the main problem. A simplified model of the pseudogap state based on the formation of smallradius polarons is considered within the cluster perturbation theory.
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13.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Polaron in-gap states in CMR manganites
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2008): 2008, June 20-25 : book of abstracts. - 2008. - Ст.24PO-7-15. - P.630
Примечания : Библиогр.: 1
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Origin of the spin polaron quasiparticles and their cooper instability in High-Tc superconductors
Коллективы : Russian Foundation for Basic Research [13-02-00523, 13-02-00909]; Dynasty Foundation
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1049-1055. - ISSN 1557-1939, DOI 10.1007/s10948-016-3383-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:15. - This study was supported by the Russian Foundation for Basic Research, projects nos. 13-02-00523, 13-02-00909 and the Dynasty Foundation.
Предметные рубрики: Model
State
Ключевые слова (''Своб.индексиров.''): cuprate high-t-c superconductors--spin polarons--spin-fermion model
Аннотация: IIn the framework of the spin-fermion model, it is shown that accounting for the strong spin-charge fluctuations between holes of copper and oxygen ions in cuprate High-T c superconductors leads to the formation of the Fermi spin-polaron quasiparticles. It is demonstrated that the large value of the binding energy of such quasiparticle is determined by the processes in which hopping intensity of the oxygen holes depends significantly on the spin configuration of holes on the copper and oxygen ions. It was found that the ensemble of such quasiparticles manifests Cooper instability and the concentration dependence of the critical temperature is in good agreement with the experimental data.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Nonadiabatic interaction of acoustic phonons with spins S=1/2 in the two-dimensional Heisenberg model
Разночтения заглавия :авие SCOPUS: Nonadiabatic interaction of acoustic phonons with spins S = 1/2 in the two-dimensional heisenberg model
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 5. - P969-977. - ISSN 1063-7761, DOI 10.1134/1.1633952
Примечания : Cited References: 18
Предметные рубрики: QUANTUM MONTE-CARLO
EU2CUO4
GD2CUO4
POLARON
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--correlation methods--crystal symmetry--magnetic couplings--magnetic moments--magnetization--monte carlo methods--quantum theory--acoustic phonons--nonadiabatic interaction--orthorhombicity--quantum spin liquid transitions--phonons
Аннотация: The ground state of a two-dimensional antiferromagnet having spins S = 1/2 and interacting with acoustic phonons is investigated in the nonadiabatic approximation using the quantum-mechanical Monte Carlo method. The critical parameters of the spin-phonon coupling, corresponding to the formation of bound spin-phonon excitations, crystal symmetry lowering, and the emergence of a gap in the spin excitation spectrum, as well as the antiferromagnet-quantum spin liquid transition, are determined. The orthorhombicity parameter, the sublattice magnetization, the violation of the spherical symmetry of spin-spin correlation functions, and the magnetic moment in Gd2CuO4 and Eu2CuO4 are calculated. (C) 2003 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Kozlov P. A.
Заглавие : Multiphonon contribution to the polaron formation in cuprates with strong electron correlations and strong electron-phonon interaction
Коллективы : Oxide-Based Materials and Devices
Место публикации : Proceedings of SPIE - The International Society for Optical Engineering: SPIE, 2017. - Vol. 10105. - , DOI 10.1117/12.2266799
Примечания : Cited References: 17. - Authors are thankful to Russian Science Foundation (project No. 14-12-00061) for financial support.
Ключевые слова (''Своб.индексиров.''): high-temperature superconductivity--cuprates--strong electronic correlations--cluster form of perturbation theory--hubbard operator--three-band p-d model--electron-phonon interaction--polaron--franck-condon broadening
Аннотация: In this work dependences of the electron band structure and spectral function in the HTSC cuprates on magnitude of electron-phonon interaction (EPI) and temperature are investigated. We use three-band p-d model with diagonal and offdiagonal EPI with breathing and buckling phonon mode in the frameworks of polaronic version of the generalized tight binding (GTB) method. The polaronic quasiparticle excitation in the system with EPI within this approach is formed by a hybridization of the local multiphonon Franck-Condon excitations with lower and upper Hubbard bands. Increasing EPI leads to transfer of spectral weight to high-energy multiphonon excitations and broadening of the spectral function. Temperature effects are taken into account by occupation numbers of local excited polaronic states and variations in the magnitude of spin-spin correlation functions. Increasing the temperature results in band structure reconstruction, spectral weight redistribution, broadening of the spectral function peak at the top of the valence band and the decreasing of the peak intensity. The effect of EPI with two phonon modes on the polaron spectral function is discussed. © 2017 SPIE.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sukhanov A. S., Pavlovskii M. S., Bourges, P.h., Walker H. C., Manna K., Felser C., Inosov D. S.
Заглавие : Magnon-polaron excitations in the noncollinear antiferromagnet Mn3Ge
Коллективы : International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM); German Research Foundation (DFG) through project B05 of the Collaborative Research Center [SFB 1143, 247310070]; German Research Foundation (DFG) through project C03 of the Collaborative Research Center [SFB 1143, 247310070]; German Research Foundation (DFG) through Wurzburg-Dresden Cluster of Excellence ct.qmat [EXC 2147, 39085490]; German Research Foundation (DFG) [SPP 2137]
Место публикации : Phys. Rev. B. - 2019. - Vol. 99, Is. 21. - Ст.214445. - ISSN 2469-9950, DOI 10.1103/PhysRevB.99.214445. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 53. - We thank S. E. Nikitin for many stimulating discussions. A.S.S. acknowledges support from the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). Work at the TU Dresden was funded by the German Research Foundation (DFG) through projects B05 and C03 of the Collaborative Research Center SFB 1143 (project i.d. 247310070), Wurzburg-Dresden Cluster of Excellence ct.qmat (EXC 2147; project i.d. 39085490), and Priority Program SPP 2137 "Skyrmionics."
Предметные рубрики: TRIANGULAR SPIN CONFIGURATION
WEAK FERROMAGNETISM
MN3SN
Аннотация: We present detailed inelastic neutron scattering measurements of the noncollinear antiferromagnet Mn3Ge. Time-of-flight and triple-axis spectroscopy experiments were conducted at the temperature of 6 K, well below the high magnetic ordering temperature of 370 K. The magnetic excitations have a 5-meV gap and display an anisotropic dispersive mode reaching ~ 90 meV at the boundaries of the magnetic Brillouin zone. The spectrum at the zone center shows two additional excitations that demonstrate characteristics of both magnons and phonons. Ab initio lattice-dynamics calculations show that these can be associated with the magnon-polaron modes resulting from the hybridization of the spin fluctuations and the low-energy optical phonons. The observed magnetoelastic coupling agrees with the previously found negative thermal expansion in this compound and resembles the features reported in the spectroscopic studies of other antiferromagnets with similar noncollinear spin structures.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudarev A. V., Shneyder E. I.
Заглавие : Lang-Firsov transformation in the generalized tight-binding method
Колич.характеристики :6 с
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2023. - Vol. 16, Is. 6. - С. 780-785. - ISSN 19971397 (ISSN); Журн. СФУ. Матем. и физ. - ISSN 23136022 (eISSN)
Примечания : Cited References: 9
Аннотация: The effects of strong electron-phonon interaction in a realistic model of a system with strong Coulomb correlations are analyzed using the Lang and Firsov transformation. It is shown that polaronic and bipolaronic transformations, widely discussed in the literature and associated with a smooth or sharp transitions in the properties of charge carriers when the strength of the electron-phonon coupling changes, determine the switching of the system between the regimes of correlated carriers, polarons or bipolarons. These transitions are controlled by the local electron-phonon interaction of the Holstein type. At the same time, the non local electron-lattice contribution associated with the modulation of the hopping integral plays a major role in the crossover of the polaron and bipolaron regimes in the limit of strong electron correlations.В настоящей работе с помощью преобразования Ланга и Фирсова анализируются эффекты сильного электрон-фононного взаимодействия в реалистичной модели системы с сильными кулоновскими корреляциями. Показано, что широко обсуждаемые в литературе поляронные и биполяронные трансформации, связанные с плавным или резким изменением свойств носителей заряда при изменении силы электрон-фононной связи, определяют переключение системы между режимами коррелированных носителей, поляронов или биполяронов. При этом существенную роль в кроссовере поляронного и биполяронного режимов в пределе сильных электронных корреляций играет нелокальный электрон-фононный вклад, связанный с модуляцией интеграла перескока между различными орбиталями.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shklyaev A. A., Korovushkin M. M., Barabanov A. F.
Заглавие : Influence of triplet states on the spectrum of collective spin-polaron excitations in a 2D kondo lattice
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 10. - P1997-2000. - ISSN 1063-7834, DOI 10.1134/S1063783411100337
Примечания : Cited References: 10. - This study was supported by the Presidium of the Russian Academy of Sciences (Program "Quantum Physics of Condensed Matter"), the Siberian Branch of the Russian Academy of Sciences (Interdisciplinary Integration project no. 53), the Ministry of Education and Science of the Russian Federation (Russian Federal Targeted Program "Scientific and Scientific-Pedagogical Personnel of the Innovative Russia" in 2009-2013), and the Russian Foundation for Basic Research (projects nos. 09-02-00127, 10-02-00614).
Предметные рубрики: SUPERCONDUCTIVITY
ANTIFERROMAGNET
Аннотация: The normal and superconducting phases of the ensemble of spin polarons in a two-dimensional Kondo lattice have been considered under the conditions when the hopping integral is comparable to the s-d exchange interaction energy. The polaron excitation spectrum and the superconducting transition temperature have been found taking into account upper triplet states. The change in the concentration dependence of the critical temperature of the transition to the superconducting phase with the relation between the hopping integral and the integral of the s-d exchange coupling has been analyzed.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Korovushkin M. M., Barabanov A. F.
Заглавие : Influence of the Coulomb repulsions on the formation of the superconducting gap of the spin-polaron quasiparticles in cuprates
Место публикации : J. Low Temp. Phys. - 2019. - Vol. 196, Is. 1-2. - P.242–252. - ISSN 0022-2291, DOI 10.1007/s10909-018-02120-3. - ISSN 1573-7357 eISSN
Примечания : Cited References: 26. - 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 (Projects Nos. 16-02-00304 and 18-02-00837) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (Projects Nos. 18-42-243002 “Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors” and 18-42-243018 “Contact phenomena and magnetic disorder in the problem of the formation and detection of topological edge states in semiconductor nanostructures”), and the grant of the President of the Russian Federation (Project MK-1398.2017.2).
Ключевые слова (''Своб.индексиров.''): cuprate superconductors--intersite coulomb interaction--spin polarons--spin-charge correlations--unconventional superconductivity
Аннотация: Taking into account the real crystalline structure of the CuO2 plane and the strong spin-fermion coupling, the influence of the on-site Coulomb repulsion of holes Up and the intersite Coulomb repulsion V2 between holes located at the next-nearest-neighbor oxygen ions on the formation of the superconducting gap with the d-wave symmetry of the order parameter of the spin-polaron quasiparticles is studied. It is shown that the formation of the resulting superconducting gap within the spin-fermion model is caused by three components. The dependence of the narrowing of the superconducting gap on the values Up and V2 is analyzed.
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