Библиотека института физики им. Л.В. Киренского СО РАН

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V., Zlotnikov A. O., Shustin M. S.
Заглавие : Majorana modes in BDI-class wire with strong Coulomb correlations [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1911.01035
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 55. - We acknowledge fruitful discussions with V.V. Valkov and V.A. Mitskan. The reported study was funded by the RAS Presidium programs for fundamental research Nos. 12 and 32, Russian Foundation for Basic Research (projects Nos. 18-32-00443, 19-02-00348), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects: ”The manifestation of Coulomb interactions and effects of bounded geometry in the properties of topological edge states of nanostructures with spin-orbit interaction” (No. 18-42-243017), ”Coulomb interactions in the problem of Majorana modes in low-dimensional systems with nontrivial topology” (No. 19-42-240011). S.A. and A.Z. are grateful to the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools, projects Nos. MK-3722.2018.2, MK-3594.2018.2.
Предметные рубрики: Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
Аннотация: In this study the problem of strong Coulomb interactions in topological superconducting wire is analyzed by means of the density-matrix-renormalization-group (DMRG) approach. To obtain the topological phase diagrams and analyze properties of edge states in the BDI-class structure the quantity called Majorana polarization is used. Its behavior agrees with the entanglement-spectrum degeneracy which has topological nature. The DMRG calculations for the Shubin-Vonsovsky-type model of the wire show the transformation of phases with Majorana single and double modes (MSMs and MDMs, respectively) under the increase of on- and inter-site correlations. In particular, the effects of MSM and MDM robustness as well as their induction are observed. It is shown that in the strongly correlated regime the contributions of single-particle excitations to the Majorana-type states significantly decrease if averaged on-site spin-dependent concentrations have comparable values. Moreover, the t−J∗−V-model is derived allowing to study the effective interactions and improve the DMRG numerics. In order to demonstrate the key role of spin and charge fluctuations in the revealed effects we analytically consider the limiting case of the effective Hamiltonian with infinitely strong on-site repulsion using the Hubbard-I approximation. Finally, the ways to probe the MSMs and MDMs via the features of caloric functions are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cao G. X., Korshunov M. M., Gao Y. Z., Le Tacon M., Singh D. J., Lin C. T.
Заглавие : Anomalous in-plane electronic scattering in charge ordered Na 0.41CoO 2•0.6H 2O
Место публикации : Phys. Rev. Lett.: American Physical Society, 2012. - Vol. 108, Is. 23. - Ст.236401. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.108.236401
Примечания : Cited References: 41. - We thank H. Habermeier, D. Mandrus, B. C. Sales, I. Eremin, I. I. Mazin, and P. J. Hirschfeld for useful discussions. G. Cao acknowledges support from NSFC (No. 10804068, 10774097). M. M. K. acknowledges support from RFBR (Grant No. 09-02-00127), Presisium of RAS program "Quantum physics of condensed matter" N5.7, Integration Grant of SBRAS-UrBRAS N40, and Russian FCP (GK 16.740.12.0731), and The Dynasty Foundation and ICFPM. Work at ORNL was supported by the Department of Energy, BES, Materials Science and Engineering Division.
Предметные рубрики: SUPERCONDUCTIVITY
TRIPLET
FLUCTUATIONS
IONS
Аннотация: We report electronic transport measurements on high quality floating zone grown NaxCoO2 and Na0.41CoO2·0.6H2O single crystals. We find an in-plane electronic scattering minimum near 11 K and a clear charge ordering at approximately 50 K. The electronic and magnetic properties in hydrated and nonhydrated Na0.41CoO2 samples are similar at higher temperature, but evolve in markedly different ways below ∼50 K, where a strong ferromagnetic tendency is observed in the hydrated sample. Model calculations show the relationship of this tendency to the structure of the Fermi surface. The results, particularly the clear differences between the hydrated and nonhydrated material show a substantially enhanced ferromagnetic tendency upon hydration. Implications for superconductivity are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Dimer state in the two-dimensional anisotropic alternated-exchange Heisenberg model
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1998. - Vol. 40, Is. 6. - P986-990. - ISSN 1063-7834, DOI 10.1134/1.1130463
Примечания : Cited References: 14
Предметные рубрики: SPIN-PEIERLS
HUBBARD-MODEL
SUPERCONDUCTIVITY
ANTIFERROMAGNETS
Аннотация: An analysis is made of the two-dimensional Heisenberg model with S = 1/2, anisotropic exchange interaction between nearest neighbors, and alternating exchange in two directions, [100] and [010] (corresponding to condensation of the (pi,pi) mode) and in one direction [100] (corresponding to condensation of the (pi,0) mode), The quantum Monte Carlo method is used to calculate the thermodynamic characteristics and the spin correlation functions which are used as the basis to determine the boundary of stability of an anisotropic antiferromagnetic with respect to alternation of exchange delta = (1 - J(x,y) / J(z))(0.4) in the (pi,pi) model and delta = (1 - J(x,y) / J(z))(0.31) in the (pi,0) model. In the (pi,0) model a disordered quantum state exists in the range (1 - J(x,y) / J(z))(0.31) delta (0.3-0.35). The energy (E - 0.68)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum spin liquid in the 2D anisotropic Heisenberg model with frustrated next nearest neighbor exchange
Место публикации : Low Temp. Phys. - 1998. - Vol. 24, Is. 8. - P.572-577. - ISSN 1063-777X, DOI 10.1063/1.593639; \b Физика низких температур
Примечания : Cited References: 25
Предметные рубрики: SQUARE-LATTICE ANTIFERROMAGNETS
VALENCE BOND STATES
SYSTEMS
SUPERCONDUCTIVITY
SYMMETRY
Аннотация: The two-dimensional (2D) Heisenberg model with anisotropic exchange (Delta = 1 - J(x)/J(z)) and with negative next nearest neighbor exchange (J(2)) with S = 1/2 is investigated by using the quantum-mechanical Monte-Carlo method. The energy, magnetic moment at a site, heat capacity, and spin-spin correlation functions are calculated. The stability regions for Neel ordering of spins as well as the strip-phase and gapless quantum spin liquid are determined in the interval Delta/2 less than or equal to J(2)/ J(1)less than or equal to 1/(2 Delta). (C) 1998 American Institute of Physics. [S1063-777X(98)00808-1].
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G., Gavrichkov V. A., Nekrasov I. A., Pchelkina Z. V., Anisimov V. I.
Заглавие : Application of the new LDA plus GTB method for the band structure calculation of n-type cuprates
Разночтения заглавия :авие SCOPUS: Application of the new LDA+GTB method for the band structure calculation of n-type cuprates
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P459-460. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.340
Примечания : Cited References: 11
Предметные рубрики: SUPERCONDUCTIVITY
PARAMETERS
DENSITY
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--superconductivity--n-type cuprates--n-type cuprates--strongly correlated electron systems--superconductivity--electronic structure--hamiltonians--mathematical models--oxide superconductors--perturbation techniques--intercluster hopping--n-type cuprates--strongly correlated electron systems--band structure
Аннотация: A novel hybrid scheme is proposed and applied for band structure calculations of undoped n-type cuprate Nd2CuO4. The ab initio LDA calculation is used to obtain single electron and Coulomb parameters of the multiband Hubbard-type model. In strong correlation regime the electronic structure within this model is calculated by the generalized tight-binding (GTB) method, that combines the exact diagonalization of the model Hamiltonian for a small cluster with perturbation treatment of the intercluster hopping and interactions. For Nd2CuO4, this scheme results in charge transfer insulator with value of the gap and band dispersion in agreement to the experimental data. (c) 2006 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Underestimating the width of the bandgap in the electronic spectra of La2CuO4
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1997. - Vol. 39, Is. 3. - P389-391. - ISSN 1063-7834, DOI 10.1134/1.1129865
Примечания : Cited References: 9
Предметные рубрики: SUPERCONDUCTIVITY
Аннотация: It is shown that the width of the bandgap determined by the simultaneous analysis of the experimental photoelectron and inverse photoemission spectra of the surface of La2CuO4 using a common energy scale is underestimated by 1 eV. The electronic and satellite structures of the spectra of La2CuO4 are calculated on the basis of the multiband p-d model and the sudden perturbation approximation. It is shown that shakedown processes shift the one-electron contour of the final two-hole configuration of the photoelectron spectrum 1 eV down the energy scale and shift the contour of the final d(10) configuration of the inverse photoemission spectrum downward by 2 eV; these shifts cause the energy splitting between the filled and empty bands to be underestimated. (C) 1997 American Institute of Physics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Borisov A. A., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Doping dependence of the band structure and chemical potential in cuprates by the generalized tight-binding method
Коллективы : International Conference on Modern Problems in Superconductivity
Место публикации : Mod. Phys. Lett. B/ International Conference on Modern Problems in Superconductivity (3 ; 2002 ; Sept. ; 9-14 ; Yalta, Ukrain). - 2003. - Vol. 17, Is. 10-12. - P.479-486. - ISSN 0217-9849, DOI 10.1142/S0217984903005500
Примечания : Cited References: 12
Предметные рубрики: CORRELATED ELECTRONS
SUPERCONDUCTIVITY
OXIDES
Аннотация: Quasiparticle band structure in hole doped CuO2 layer is calculated with account for strong electron correlations in the framework of multiband p-d model. For undoped layer we obtain the charge-transfer antiferromagnetic insulator. With doping unusual impurity-like quasiparticle appears at the top of the valence band with spectral weight proportional to doping concentration. In the overdoped regime the band structure in the paramagnetic phase results in the doping dependent Fermi surface in agreement to ARPES data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klauss H. H., Luetkens H., Klingeler R., Hess C., Litterst F. J., Kraken M., Korshunov M. M., Eremin I., Drechsler S. L., Khasanov R., Amato A., Hamann-Borrero J. E., Leps N., Kondrat A., Behr G., Werner J., Buchner B.
Заглавие : Commensurate spin density wave in LaFeAsO: A local probe study
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2008. - Vol. 101, Is. 7. - Ст.77005. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.101.077005
Примечания : Cited References: 28
Предметные рубрики: LAYERED QUATERNARY COMPOUND
SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): arsenic compounds--chlorine compounds--ferromagnetism--magnetic materials--magnetic properties--magnetization--magnets--molybdenum--phase transitions--spin density waves--commensurate spin density wave--external fields--magnetic orders--muon spin relaxations--order parameter--ordered moments--probe measurements--ssbauer spectroscopy--structural phase transition--sublattice magnetizations--temperature dependences--spin dynamics
Аннотация: We present a detailed study on the magnetic order in the undoped mother compound LaFeAsO of the recently discovered Fe-based superconductor LaFeAsO(1-x)F(x). In particular, we present local probe measurements of the magnetic properties of LaFeAsO by means of (57)Fe Mossbauer spectroscopy and muon-spin relaxation in zero external field along with magnetization and resistivity studies. These experiments prove a commensurate static magnetic order with a strongly reduced ordered moment of 0.25(5)mu(B) at the iron site below T(N)=138 K, well separated from a structural phase transition at T(S)=156 K. The temperature dependence of the sublattice magnetization is determined and compared to theory. Using a four-band spin density wave model both, the size of the order parameter and the quick saturation below T(N) are reproduced.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd Yu. S., Dubrovskii A. A., Shaikhutdinov K. A.
Заглавие : Effect of heterovalent substitution of rare-earth elements on the magnetic and transport properties of YBa2Cu3O7
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 11. - P2047-2051. - ISSN 1063-7834, DOI 10.1134/S1063783407110054
Примечания : Cited References: 18
Предметные рубрики: PR
SUPERCONDUCTIVITY
CE
ND
TRANSITION
SYSTEM
LA
Аннотация: The Y(1-x) Ce (x) Ba2Cu3O7 system with low cerium concentrations has been synthesized. The cerium solubility limit measured using x-ray powder diffraction analysis is about 2.4 at. %. The temperature dependences of the magnetization M(T) are measured for samples cooled in a magnetic field (FC) and in a zero field (ZFC). The difference between the magnetizations M-ZFC-M-FC at 77.4 K, which is proportional to the pinning potential, passes through a maximum at x = 0.0156. This concentration corresponds to the average distance (equal to eight lattice constants) between the impurity ions in the plane of the rare-earth elements, which is comparable to the diameter of Abrikosov vortices in YBa2Cu3O7.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Donkov A., Eremin I., Knolle J., Korshunov M. M.
Заглавие : Electron-Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate NaxCoO2
Разночтения заглавия :авие SCOPUS: Electron-phonon interaction and phonon renormalization in the lamellar cobaltate Na x CoO 2
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2009. - Vol. 22: International Conference on Quantum Phenomena in Complex Matters (JUL 26-AUG 01, 2008, Erice, ITALY), Is. 1. - P37-40. - ISSN 1557-1939, DOI 10.1007/s10948-008-0372-6
Примечания : Cited References: 16
Предметные рубрики: SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): electron-phonon interaction--superconductivity--sodium cobaltate--electron-phonon interaction--sodium cobaltate--superconductivity--brillouin zones--cobaltate--conducting electrons--conduction electrons--doping dependences--feedback effects--matrix elements--phonon frequencies--phonon modes--raman experiments--renormalization--sodium cobaltate--sodium cobaltates--atoms--cobalt compounds--critical current density (superconductivity)--electric conductivity--electron-phonon interactions--electrons--flow interactions--penetration depth (superconductivity)--sodium--superconductivity--phonons
Аннотация: We study theoretically the electron-phonon interaction in NaxCoO2. For the A(1g) and E-1g phonon modes found in Raman experiments, we calculate the matrix elements of the electron-phonon interaction. Analyzing the feedback effect of the conduction electrons on the phonon frequency., we investigate the doping dependence of these two phonon modes. Due to the momentum dependence of the electron-phonon interaction, we find the strongest renormalization of the E-1g mode around the Brillouin zone boundary which should be observed in the neutron scattering. At the same time, the A(1g) mode shows the strongest coupling to the conducting electrons around the G point and reveals its doping dependence in the Raman experiments. Our results shed light on the possible importance of the electron-phonon interaction in the lamellar sodium cobaltates.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Gokhfeld D. M., Savitskaya N. E., Terentjev K. Yu., Popkov S. I., Mistonov A. A., Grigoryeva N. A., Zakhidov A., Grigoriev, S., V
Заглавие : Flux pinning mechanisms and a vortex phase diagram of tin-based inverse opals
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [17-72-10067]
Место публикации : Supercond. Sci. Technol. - 2019. - Vol. 32, Is. 11. - Ст.115004. - ISSN 0953-2048, DOI 10.1088/1361-6668/ab3db7. - ISSN 1361-6668(eISSN)
Примечания : Cited References: 31. - The work was supported by the Russian Foundation for Basic Research, project no. 17-72-10067.
Предметные рубрики: SUPERCONDUCTIVITY
Аннотация: Three-dimensional periodic tin structures were synthesized by filling pores in silicon opals with a sphere diameter of 194 nm (Sn190) and 310 nm (Sn300). The samples were examined by the ultra-small-angle x-ray diffraction method, energy dispersive x-ray microanalysis and scanning electron microscopy. It was found that the inverse opal structure consists of tin nanoparticles inscribed in octahedral and tetrahedral pores with diameters of 128 nm and 70 nm for the sample Sn300, and 80 nm and 42 nm for the sample Sn190. The study of the magnetic properties of the samples by SQUID magnetometry showed that magnetization reversal curves exhibit hysteretic behavior. The mechanisms of magnetic flux pinning in the samples depend on the size of the tin nanoparticles. Tin nanoparticles in Sn300 behave like a classical type-I superconductor. The hysteretic behavior of the magnetization reversal curves at low magnetic fields is due to the formation of a network of superconducting contours in Sn300. These superconducting contours effectively trap the magnetic flux. The octahedral tin nanoparticles in Sn190 remain type-I superconductors, but smaller tetrahedral particles behave like type-II superconductors. Type-I and II superconducting particles in Sn190 lead to the coexistence of different mechanisms of flux pinning These are flux trapping by superconducting contours at low magnetic fields and flux pinning by tetrahedral particles due to the surface barrier at high magnetic fields.
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12.

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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2012. - Vol. 25, Is. 5. - P.1379-1382. - ISSN 1557-1939, DOI 10.1007/s10948-012-1523-3
Примечания : Cited References: 28. - We are grateful to P. Fulde, Yu. Kagan, K. I. Kugel, N.V. Prokof'ev, P. Nozieres, and C. M. Varma for the numerous stimulating discussions. We acknowledge financial support of the RFBR Grant No. 11-02-00741.
Предметные рубрики: FERMI GAS
SUPERCONDUCTIVITY
SUPERFLUIDITY
TEMPERATURE
REPULSION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): electron-polaron effect--two-band hubbard model--marginality--anomalous resistivity
Аннотация: We search for anomalous normal and superconductive behavior in the two-band Hubbard model with one narrow band. We analyze the influence of the electron–polaron effect and the Altshuler–Aronov effect on effective mass enhancement and scattering times of heavy and light components in the clean case. We find anomalous behavior of resistivity at high temperatures TW∗hT W_{h}. *} both in 3D and 2D situations. The SC instability in the model is governed by an enhanced Kohn–Luttinger effect for p-wave pairing of heavy electrons via polarization of light electrons.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Woelfle P.
Заглавие : Manifestation of the upper Hubbard band in the 2D Hubbard model at low electron density
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 9-10. - P.834-839. - ISSN 1063-777X, DOI 10.1063/1.3670026; \b Физика низких температур
Примечания : Cited References: 31. - This work was supported by RFBR Grants No. 11-0200798 and 11-02-00741.
Предметные рубрики: 2-DIMENSIONAL FERMI GAS
LIQUID BEHAVIOR
SPECTRAL FUNCTIONS
TRANSITION METALS
SUPERCONDUCTIVITY
FERROMAGNETISM
DIMENSIONS
SCATTERING
STATE
Ключевые слова (''Своб.индексиров.''): electron density--electronic density of states--fermi liquid--green's function methods--hubbard model
Аннотация: We consider the 2D Hubbard model in the strong-coupling case (U W) and at low electron density (nd(2) ≪1). We find an antibound state as a pole in the two-particle T-matrix. The contribution of this pole in the self-energy reproduces a two-pole structure in the dressed one-particle Green-function similar to the Hubbard-I approximation. We also discuss briefly the Engelbrecht-Randeria mode which corresponds to the pairing of two holes below the bottom of the band for U W and low electron density. Both poles produce nontrivial corrections to Landau Fermi-liquid picture already at low electron density but do not destroy it in 2D.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article
Место публикации : Low Temp. Phys.: American Institute of Physics, 2012. - Vol. 38, Is. 9. - P.874-879. - ISSN 1063-777X, DOI 10.1063/1.4752091
Примечания : Cited References: 59. - We acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N. M. Plakida, and N. V. Prokof'ev. M. Yu. K's work was supported by RFBR Grant No 11-02-00741-a.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
2-BAND HUBBARD-MODEL
LOW ELECTRON-DENSITY
FRACTIONAL-STATISTICS
PHASE-SEPARATION
SUPERCONDUCTIVITY
GAS
ENHANCEMENT
MECHANISM
Ключевые слова (''Своб.индексиров.''): d-wave superconductivity--electron density--electron spin polarisation--high-temperature superconductors--hubbard model--superconducting transition temperature--t-j model--two-dimensional electron gas
Аннотация: We demonstrate the possibility of triplet p-wave pairing at low electron density a large number of models such as 3D and 2D Fermi-gas models with hard-core repulsion, 3D and 2D Hubbard models, and the Shubin-Vonsovsky model. The critical temperature for p-wave pairing can be considerably higher in the spin-polarized case or even in a two-band situation at low density and can reach experimentally observable values of 1–5 K. We also discuss briefly the d-wave pairing and high-Tc superconductivity with Tc ∼ 100 K which arise in the extended Hubbard model and in the generalized t-Jmodel when close to half-filling.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komarov K. K., Dzebisashvili D. M.
Заглавие : Effect of Coulomb repulsion on the London penetration depth in cuprate superconductors [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1912.04577
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 55. - The work was financially supported by the Presidium of the Russian Academy of Sciences the Program No.12 ”Fundamental problems of high-temperature superconductivity”, the Russian Foundation for Basic Research (project #18-02-00837, #20-32-70059), the Government of Krasnoyarsk Region, the Krasnoyarsk Regional Science and Technology Support Fund (projects: #18-42-240014 ”One-orbit effective model of an ensemble of spin-polaron quasiparticles in the problem of describing the intermediate state and pseudogap behavior of cuprate superconductors” and #18-42-243002 ”Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors”). The work of K.K.K. was supported by the Council for Grants of the President of the Russian Federation (project MK-3722.2018.2).
Предметные рубрики: Superconductivity
Strongly Correlated Electrons
Аннотация: We study the effect of Coulomb repulsion between oxygen holes on the London penetration depth λ based on the concept of spin-polaron nature of Fermi quasiparticles in cuprates superconductors. It is shown that for the generally accepted values of the parameters of the spin-fermion model, taking into account the Coulomb interaction, both the one-site Hubbard Up and interaction between the holes on next-nearest-neighbor oxygen ions V2, allows one to achieve a much better agreement of the calculated temperature dependencies of the value λ−2 with the experimental data in La2−xSrxCuO4 with optimal doping.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I.
Заглавие : Doping evolution of itinerant magnetic fluctuations in Fe-based pnictides
Коллективы :
Место публикации : Europhys. Lett. - 2008. - Vol. 83, Is. 6. - Ст.67003. - ISSN 0295-5075, DOI 10.1209/0295-5075/83/67003
Примечания : Cited References: 18. - We would like to thank B. BUCHNER, S.-L. DRECHSLER, D. EFREMOV, P. FULDE, I. MAZIN, R. MOESSNER and D. PARKER for useful discussions. IE acknowledges support from Volkswagen Foundation.
Предметные рубрики: SUPERCONDUCTIVITY
ORDER
Аннотация: Employing the four-band tight-binding model, we study theoretically the doping dependence of the spin response in the normal state of novel Fe-based pnictide superconductors. We show that the commensurate spin density wave (SDW) transition that arises due to interband scattering between the hole alpha-pockets and the electron beta-pockets disappears already at the doping concentration x approximate to 0.04 reflecting the evolution of the Fermi surfaces. Correspondingly, with further increase of the doping the antiferromagnetic fluctuations are suppressed for x 0.1 and the imaginary part of the spin susceptibility at antiferromagnetic wave vector becomes nearly temperature independent. At the same time, we observe that the uniform susceptibility deviates from the Pauli-like behavior and is increasing with increasing temperature reflecting the activation processes for the alpha-Fermi surfaces up to temperatures of about T = 800 K. With increase of the doping the absolute value of the uniform susceptibility lowers and its temperature dependence changes. In particular, it is a constant at low temperatures and then decreases with increasing temperature. We discuss our results in a context of recent experimental data. Copyright (C) EPLA, 2008
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Ovchinnikov S. G., Singh D. J.
Заглавие : Effect of frustrations on magnetism in the Ru double perovskite Sr2YRuO6
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2003. - Vol. 68, Is. 2. - Ст.24409. - ISSN 1098-0121, DOI 10.1103/PhysRevB.68.024409
Примечания : Cited References: 24
Предметные рубрики: MOTT TRANSITION
LATTICE
SPIN
ANTIFERROMAGNETISM
SUPERCONDUCTIVITY
FERROMAGNETISM
Аннотация: Localized Ru5+ spins in Sr2YRuO6 form a fcc lattice with an antiferromagnetic (AFM) nearest-neighbor (NN) coupling J approximate to 25 meV and rather low Neel temperature T-N= 26 K. Analysis of the electronic structure of Sr2RuO4 results in the effective Heisenberg model. We have studied the effect of frustrations on the AFM type-I structure of Sr2YRuO6 in the spin-wave approximation. In the model with only NN coupling the AFM state is unstable due to frustrations, and T-N = 0. Stabilization of the AFM state occurs due to the next-nearest-neighbor coupling I or due to the magnetic anisotropy D. Very small values D/J similar to I/J less than or equal to 10(-3) are enough to obtain the experimental values of T-N and sublattice magnetization m = 1.85 mu(B) /Ru (62% from the nominal S = 3/2 value).
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Comparison of the electronic structure of the Hubbard and t - J models within the cluster perturbation theory
Коллективы : RFBR [13-02-01395-a, 14-02-31677-mol-a, 14-02-00186-a]; Ministry of Education and Science of Russia [3085, SibFU 2014 GF-2]; [NSh-2886.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 90, Is. 24. - Ст.245104. - ISSN 1098-0121, DOI 10.1103/PhysRevB.90.245104. - ISSN 1550-235X
Примечания : Cited References: 37. - This work is supported by RFBR (Grants No. 13-02-01395-a, No. 14-02-31677-mol-a, and No. 14-02-00186-a), the Ministry of Education and Science of Russia (Government Contract No. 3085, SibFU 2014 GF-2), and a grant of the Russian President (Grant No. NSh-2886.2014.2).
Предметные рубрики: FERMION SYSTEMS
SUPERCONDUCTIVITY
METAL
Аннотация: Electronic dispersion and density of states (DOS) have been calculated for the Hubbard model and the t−J and t−J∗ models with three-site correlated hopping by the cluster perturbation theory. We have found a rather strong quantitative difference both in dispersion and DOS at all doping for the Hubbard and t−J models at the energy scale ω≳t. The three-site correlated hopping addition results in an almost negligible difference for the Hubbard and t−J∗ models. Close to the Fermi energy, at the scale ω≲J, the electronic structure of all three models is similar. We have found the line of zeros of the Green function for the t−J model that has been previously obtained for the Hubbard model by cellular dynamical mean-field theory calculations.
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20.

Вид документа : Однотомное издание
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Shneyder E. I., Togushova Yu.N., Gavrichkov V. A., Korshunov M. M.
Заглавие : Magnetic mechanisms of pairing in strongly correlated electron system of copper oxides [Electronic resource]
Место публикации : arXiv. - 2015. - Ст.eprint arXiv:1510.08640
Примечания : Cited References: 214. - The authors acknowledge support from FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK 16.740.12.0731 and GK 16.740.11.0740), RFBR (Grants 12-02-31534 and 12-02-31597), Siberian Federal University (Theme #F-11), Governmental support of leading scientific schools of Russia (NSh-1044.2012.2), Program of SB RAS #44, Presidium of RAS program #20.7. EIS, IAM, and MMK are grateful to The Dynasty Foundation and ICFPM forthe financial supportIn book.: Recent advances in superconductivity research", ed. by C.B. Taylor, 321 p., Nova Science Publishers Inc. New York, 2013 ISBN: 978-1-62618-406-0, Chapter 6
Предметные рубрики: Condensed matter-- Strongly correlated electrons
Superconductivity
Ключевые слова (''Своб.индексиров.''): strong electronic correlations--cuprates--hubbard operators--electronic structure--quantum phase transitions--magnetic mechanism of pairing
Аннотация: The multielectron LDA+GTB approach has been developed to calculate electronic structure of strongly correlated cuprates. At low energies the effective Hamiltonian of the t−t′−t"−t⊥−J∗−J⊥-model has been derived with parameters coming from the ab initio calculation for LSCO. The electronic structure of LSCO has been calculated self-consistently with the short-range antiferromagnetic order for various doping level. Two Lifshitz-type quantum phase transitions with Fermi surface topology changes have been found at dopings xc1=0.15 and xc2=0.24. Its effect on normal and superconducting properties has been calculated. The interatomic exchange parameter and its pressure dependence has been calculated within LDA+GTB scheme. The magnetic mechanisms of d-wave pairing induced by static and dynamical spin correlations are discussed. Simultaneous treatment of magnetic and phonon pairing results in the conclusion that both contributions are of the same order. For two layer cuprates like YBCO the interlayer hopping and exchange effects on the electronic structure and doping dependence of Tc is discussed as well as the Coulomb interaction induced mechanism of pairing.
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