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Anomalous in-plane electronic scattering in charge ordered Na 0.41CoO 2•0.6H 2O / G. X. Cao [et al.] // Phys. Rev. Lett. - 2012. - Vol. 108, Is. 23. - Ст. 236401, DOI 10.1103/PhysRevLett.108.236401. - 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. . - ISSN 0031-9007

РУБ Physics, Multidisciplinary
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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Держатели документа:
[Cao, Guixin
Gao, Yuze
Le Tacon, Mathieu
Lin, Chengtian] Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany
[Cao, Guixin] Shanghai Univ, Dept Phys, Shanghai 200444, Peoples R China
[Cao, Guixin] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA
[Korshunov, Maxim M.] Univ Florida, Dept Phys, Gainesville, FL 32611 USA
[Korshunov, Maxim M.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Korshunov, Maxim M.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Singh, David J.] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA

Доп.точки доступа:
Cao, G. X.; Korshunov, M. M.; Коршунов, Максим Михайлович; Gao, Y. Z.; Le Tacon, M.; Singh, D. J.; Lin, C. T.
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Kagan, M. Y.
Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band / M. Y. Kagan, V. V. Val'kov // J. Supercond. Nov. Magn. - 2012. - Vol. 25, Is. 5. - P. 1379-1382, DOI 10.1007/s10948-012-1523-3. - 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. . - ISSN 1557-1939

РУБ Physics, Applied + Physics, Condensed Matter
Рубрики:
FERMI GAS
   SUPERCONDUCTIVITY
   SUPERFLUIDITY
   TEMPERATURE
   REPULSION
   SYSTEMS
Кл.слова (ненормированные):
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 T>W∗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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Держатели документа:
[Kagan, M. Y.] PL Kapitza Inst Phys Problems, Moscow 119334, Russia
[Val'kov, V. V.] Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
P.L. Kapitza Institute for Physical Problems, Kosygina st. 2, 119334 Moscow, Russian Federation
Kirenskii Institute of Physics, Akademgorodok 50, Building 38, 660036 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Каган, Максим Юрьевич
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Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article / M. Y. Kagan [et al.] // Low Temp. Phys. - 2012. - Vol. 38, Is. 9. - P. 874-879, DOI 10.1063/1.4752091. - 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. . - ISSN 1063-777X

РУБ Physics, Applied
Рубрики:
T-J MODEL
   SUPERFLUID TRANSITION-TEMPERATURE
   2-BAND HUBBARD-MODEL
   LOW ELECTRON-DENSITY
   FRACTIONAL-STATISTICS
   PHASE-SEPARATION
   SUPERCONDUCTIVITY
   GAS
   ENHANCEMENT
   MECHANISM
Кл.слова (ненормированные):
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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Публикация "на русском языке" Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density [Текст] : Review Article / M. Yu. Kagan [et al.] // Физ. низких температур : Физико-технический институт низких температур им. Б.И. Веркина НАН Украины, 2012. - Т. 38 Вып. 9.- С.1102-1108

Держатели документа:
[Kagan, M. Yu.] Kapitza Inst Phys Problems, Moscow 19334, Russia
[Efremov, D. V.] Max Planck Inst Festkorperforsch, D-70569 Stuttgart, Germany
[Mar'enko, M. S.] Hofstra Univ, Dept Phys & Astron, Hempstead, NY 11549 USA
[Val'kov, V. V.] Kirenskii Inst Phys, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Kagan, M. Y.; Каган, Максим Юрьевич; Efremov, D. V.; Mar'enko, M. S.; Val'kov, V. V.; Вальков, Валерий Владимирович
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Kuz'min, V. I.
Comparison of the electronic structure of the Hubbard and t - J models within the cluster perturbation theory / V. I. Kuz'min, S. V. Nikolaev, S. G. Ovchinnikov // Phys. Rev. B. - 2014. - Vol. 90, Is. 24. - Ст. 245104, DOI 10.1103/PhysRevB.90.245104. - 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). . - ISSN 1098-0121. - ISSN 1550-235X

РУБ Physics, Condensed Matter
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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Держатели документа:
SB RAS, LV Kirensky Inst Phys, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660041, Russia

Доп.точки доступа:
Nikolaev, S. V.; Николаев, Сергей Викторович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Кузьмин, Валерий Ипполитович; 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]
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Val'kov, V. V.
d-Wave pairing in an ensemble of spin polaron quasiparticles in the spin-fermion model of the electronic structure of the CuO2 plane / V. V. Val'kov, D. M. Dzebisashvili, A. F. Barabanov // Phys. Lett. A. - 2015. - Vol. 379, Is. 5. - P. 421-426, DOI 10.1016/j.physleta.2014.11.036. - Cited References:26. - This study was supported by the Russian Foundation for Basic Research,projects Nos. 13-02-00523, 13-02-00909 and 13-02-98013 (Siberia) and theDynasty Foundation. . - ISSN 0375. - ISSN 1873-2429. -

РУБ Physics, Multidisciplinary
Рубрики:
SUPERCONDUCTIVITY
ANTIFERROMAGNETISM
Кл.слова (ненормированные):
Hight-temperature cuprate superconductors -- Tree-band p-d model -- Spin -- polaron -- Strong electron correlations
Аннотация: It is demonstrated for the first time that the strong coupling between spin moments of copper ions and oxygen holes, which arises upon hybridization mixing of two hole subsystems in the Emery model, not only affects the formation of spin polaron quasiparticles but also ensures effective attraction between them via the exchange interaction. This results in the Cooper instability with d-wave pairing in a 2D ensemble of spin polaron quasiparticles. The T-x phase diagram obtained using this approach agrees well with the available experimental data. (C) 2014 Elsevier B.V. All rights reserved.

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Держатели документа:
RAS, LV Kirensky Inst Phys, SB, Krasnoyarsk 660036, Russia.
Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia.
Inst High Pressure Phys, Troitsk 142098, Moscow Region, Russia.

Доп.точки доступа:
Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Barabanov, A. F.; Вальков, Валерий Владимирович; Dynasty Foundation; Russian Foundation for Basic Research (Siberia) [13-02-00523,13-02-00909, 13-02-98013]
}
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Makarov, I. A.
Temperature dependence of the electronic structure of La2CuO4 in the multielectron LDA+GTB approach / I. A. Makarov, S. G. Ovchinnikov // J. Exp. Theor. Phys. - 2015. - Vol. 121, Is. 3. - P. 457-464, DOI 10.1134/S1063776115090174. - Cited References: 38. - The work was supported by the Russian Science Foundation (project no. 14-12-00061) . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
Copper oxides
   Model
   Superconductivity
   Excitations
   Instability
   Spectrum
   States
   Order
Аннотация: The band structure of La2CuO4 in antiferromagnetic and paramagnetic phases is calculated at finite temperatures by the multielectron LDA+GTB method. The temperature dependence of the band spectrum and the spectral weight of Hubbard fermions is caused by a change in the occupation numbers of local multielectron spin-split terms in the antiferromagnetic phase. A decrease in the magnetization of the sublattice with temperature gives rise to new bands near the bottom of the conduction band and the top of the valence band. It is shown that the band gap decreases with increasing temperature, but La2CuO4 remains an insulator in the paramagnetic phase as well. These results are consistent with measurements of the red shift of the absorption edge in La2CuO4 with increasing temperature. © 2015, Pleiades Publishing, Inc.

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Публикация на русском языке Макаров, Илья Анатольевич. Температурная зависимость электронной структуры La2CuO4 в многоэлектронном подходе LDA+GTB [Текст] / И. А. Макаров, С. Г. Овчинников // Журн. эксперим. и теор. физ. : Наука, 2015. - Т. 148 Вып. 3. - С. 526-534

Держатели документа:
Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Макаров, Илья Анатольевич
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    Structural and magnetic properties of Fe1−xCoxSe1.09 nanoparticles obtained by thermal decomposition / O. A. Li [et al.] // Mater. Res. Express. - 2015. - Vol. 2, No. 12. - Ст. 126501, DOI 10.1088/2053-1591/2/12/126501. - Cited References: 30. - This work is supported by the Ministry of Science and Technology of Taiwan (MOST103-2811-M-153 -001 and MOST102-2112-M-153 -002 -MY3). . - ISSN 2053-1591
   Перевод заглавия: Структурные и магнитные свойства наночастиц Fe1−xCoxSe1.09, полученных тепловым разложением

РУБ Materials Science, Multidisciplinary
Рубрики:
X-RAY-DIFFRACTION
   MOSSBAUER-SPECTROSCOPY
   CRYSTAL-STRUCTURES
   IRON SELENIDES
   SUPERCONDUCTIVITY
   FeSe
   MARCASITE
   PYRITE
Кл.слова (ненормированные):
nanoparticles -- chalcogenide -- iron-cobalt selenide -- ferrimagnetism -- paramagnetism -- Mossbauer spectroscopy
Аннотация: A series of Fe1−xCoxSe1.09 (x = 0 to ) nanoparticles were synthesized by thermal decomposition method. Particles in composition range Fe0.5Co0.5Se1.09 to CoSe1.09 crystallized in monoclinic structure of Co6.8Se8 , while FeSe1.09 crystallized in hexagonal structure of FeSe achavalite. Magnetization dependences on temperature and external magnetic field reveal complicated magnetic behavior and correspond to the sum of paramagnetic and superparamagnetic response. Mössbauer spectra contain several paramagnetic doublets with parameters corresponding to nonequivalent positions of divalent and trivalent iron cations with low spin. The nonequivalent positions appeared due to inhomogeneous distribution of Co ions or metal vacancies in iron surrounding.

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Доп.точки доступа:
Li, Oksana A.; Lin, Chun-Rong; Chen, Hung-Yi; Hsu, Hua-Shu; Wu, Kai-Wun; Tseng, Yaw-Teng; Bayukov, O. A.; Баюков, Олег Артемьевич; Edelman, I. S.; Эдельман, Ирина Самсоновна; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Shih, Kun-Yauh
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    Magnetic mechanisms of pairing in strongly correlated electron system of copper oxides / S. G. Ovchinnikov [et al.] // arXiv. - 2015. - Ст. eprint arXiv:1510.08640. - 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 support. - In 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
Рубрики:
Condensed matter--Strongly correlated electrons
   Superconductivity
Кл.слова (ненормированные):
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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Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Makarov, I. A.; Макаров, Илья Анатольевич; Shneyder, E. I.; Шнейдер, Елена Игоревна; Togushova, Yu.N.; Тогушова Ю.Н.; Gavrichkov, V. A.; Гавричков, Владимир Александрович; Korshunov, M. M.; Коршунов, Максим Михайлович
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    Transition between large and small polaron states in the electronic structure of HTSC cuprates / I. A. Makarov [et al.] // J. Supercond. Nov. Magn. - 2016. - Vol. 29, Is. 4. - P. 1063-1068, DOI 10.1007/s10948-016-3375-8. - 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. . - ISSN 1557-1939. - ISSN 1557-1947
   Перевод заглавия: Переход между состояниями большого и малого полярона в электронной структуре ВТСП купратов

РУБ Physics, Applied + Physics, Condensed Matter
Рубрики:
SUPERCONDUCTIVITY
Кл.слова (ненормированные):
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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Доп.точки доступа:
Makarov, I. A.; Макаров, Илья Анатольевич; Shneyder, E. I.; Шнейдер, Елена Игоревна; Kozlov, P. A.; Козлов, Пётр Александрович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; RFBR [13-02-01395 a, 14-02-31677 mol_a]
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10.

Influence of triplet states on the spectrum of collective spin-polaron excitations in a 2D kondo lattice / V. V. Val'kov [et al.] // Phys. Solid State. - 2011. - Vol. 53, Is. 10. - P. 1997-2000, DOI 10.1134/S1063783411100337. - 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). . - ISSN 1063-7834

РУБ Physics, Condensed Matter
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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Держатели документа:
[Val'kov, V. V.
Shklyaev, A. A.
Korovushkin, M. M.] Russian Acad Sci, Siberian Branch, Inst Phys, Krasnoyarsk 660036, Russia
[Val'kov, V. V.] Reshetnev Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
[Barabanov, A. F.] Russian Acad Sci, Inst High Pressure Phys, Troitsk 142092, Moscow Oblast, Russia
ИФ СО РАН
Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
Reshetnev Siberian State Aerospace University, pr. im. Gazety Krasnoyarskii Rabochii 31, Krasnoyarsk 660014, Russian Federation
Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow oblast 142092, Russian Federation

Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Shklyaev, A. A.; Korovushkin, M. M.; Коровушкин, Максим Михайлович; Barabanov, A. F.
}
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11.

Kagan, M. Y.
Manifestation of the upper Hubbard band in the 2D Hubbard model at low electron density / M. Y. Kagan, V. V. Val'kov, P. . Woelfle // Low Temp. Phys. - 2011. - Vol. 37, Is. 9-10. - P. 834-839 ; Физика низких температур, DOI 10.1063/1.3670026. - Cited References: 31. - This work was supported by RFBR Grants No. 11-0200798 and 11-02-00741. . - ISSN 1063-777X

РУБ Physics, Applied
Рубрики:
2-DIMENSIONAL FERMI GAS
   LIQUID BEHAVIOR
   SPECTRAL FUNCTIONS
   TRANSITION METALS
   SUPERCONDUCTIVITY
   FERROMAGNETISM
   DIMENSIONS
   SCATTERING
   STATE
Кл.слова (ненормированные):
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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Держатели документа:
[Kagan, M. Yu.] PL Kapitza Inst Phys Problem, Moscow 119334, Russia
[Val'kov, V. V.] LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
[Woelfle, P.] Karlsruhe Inst Technol, Inst Theoret Condensed Matter Phys, D-76131 Karlsruhe, Germany
ИФ СО РАН
P.L. Kapitza Institute for Physical Problem, 2 ul. Kosygina, Moscow 119334, Russian Federation
Kirensky Institute of Physics, Akademgorodok, 50, bld. 38, Krasnoyarsk 660036, Russian Federation
Institute for Theoretical Condensed Matter physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, Karlsruhe D-76131, Germany

Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Woelfle, P.

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12.

Val'kov, V. V.
Effective Interactions and the Nature of Cooper Instability of Spin Polarons in the 2D Kondo Lattice / V. V. Val'kov, M. M. Korovushkin, A. F. Barabanov // JETP Letters. - 2008. - Vol. 88, Is. 6. - P. 370-374, DOI 10.1134/S0021364008180069. - Cited References: 9. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Microphysics"), the Russian Foundation for Basic Research (project no. 06-02-16100), and the Siberian Branch, Russian Academy of Sciences (integration project no. 3.4). The work of M. M. Korovushkin was supported by the Krasnoyarsk Regional Science Foundation (project no. 18G). . - ISSN 0021-3640

РУБ Physics, Multidisciplinary
Рубрики:
SUPERCONDUCTIVITY
ANTIFERROMAGNET
MODEL
Аннотация: It has been shown that two- and three-center interactions arise in the strong-coupling regime for the 2D Kondo lattice; these interactions both induce and suppress the Cooper instability. It is important that, in contrast to the t-J* model, the three- center interactions promote the Cooper pairing and ensure the appearance of the superconducting phase with a high critical temperature T(c). The calculated concentration dependences of T(c) agree well with the experimental data for the cuprate superconductors.

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Держатели документа:
[Val'kov, V. V.
Korovushkin, M. M.] Russian Acad Sci, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia
[Val'kov, V. V.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Val'kov, V. V.] Siberian State Airspace Univ, Krasnoyarsk 660074, Russia
[Barabanov, A. F.] Russian Acad Sci, Inst High Pressure Phys, Troitsk 142190, Moscow Region, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russian Federation
Siberian Federal University, Krasnoyarsk 660041, Russian Federation
Siberian State Airspace University, Krasnoyarsk 660074, Russian Federation
Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow region 142190, Russian Federation

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Barabanov, A. F.; Вальков, Валерий Владимирович
}
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13.

Korshunov, M. M.
Doping evolution of itinerant magnetic fluctuations in Fe-based pnictides / M. M. Korshunov, I. . Eremin // Europhys. Lett. - 2008. - Vol. 83, Is. 6. - Ст. 67003, DOI 10.1209/0295-5075/83/67003. - 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. . - ISSN 0295-5075

РУБ Physics, Multidisciplinary
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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Держатели документа:
[Korshunov, M. M.
Eremin, I.] Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
[Korshunov, M. M.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Eremin, I.] Tech Univ Carolo Wilhelmina Braunschweig, Inst Math & Theoret Phys, D-38106 Braunschweig, Germany
ИФ СО РАН
Max-Planck-Institut fur Physik Komplexer Systeme, 01187 Dresden, EU, Germany
L.V. Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Institute fur Mathematische und Theoretische Physik, TU-Braunschweig, 38106 Braunschweig, EU, Germany
Kazan State University, 420008 Kazan, Russian Federation

Доп.точки доступа:
Eremin, I.; Коршунов, Максим Михайлович
}
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14.

Commensurate spin density wave in LaFeAsO: A local probe study / H. H. Klauss [et al.] // Phys. Rev. Lett. - 2008. - Vol. 101, Is. 7. - Ст. 77005, DOI 10.1103/PhysRevLett.101.077005. - Cited References: 28 . - ISSN 0031-9007

РУБ Physics, Multidisciplinary
Рубрики:
LAYERED QUATERNARY COMPOUND
SUPERCONDUCTIVITY
Кл.слова (ненормированные):
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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[Klauss, H. -H.] Tech Univ Dresden, Inst Festkorperphys, D-01069 Dresden, Germany
Amato, A.] Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland
Buechner, B.] Leibniz Inst Festkorper & Weskstoffforsch IFW, D-01171 Dresden, Germany
Kraken, M.] Tech Univ Carolo Wilhelmina Braunschweig, Inst Phys Kondensierten Mat, D-38106 Braunschweig, Germany
Eremin, I.] Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
[Korshunov, M. M.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Eremin, I.] Tech Univ Carolo Wilhelmina Braunschweig, Inst Math Phys, D-38106 Braunschweig, Germany
Institut fur Festkorperphysik, TU Dresden, D-01069 Dresden, Germany
Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
Leibniz-Institut fur Festkorper- und Werkstoffforschung (IFW) Dresden, D-01171 Dresden, Germany
Institut fur Physik der Kondensierten Materie, TU Braunschweig, D-38106 Braunschweig, Germany
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany
L.V. Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Institut fur Mathematische Physik, TU Braunschweig, D-38106 Braunschweig, Germany

Доп.точки доступа:
Klauss, H. H.; Luetkens, H.; Klingeler, R.; Hess, C.; Litterst, F. J.; Kraken, M.; Korshunov, M. M.; Коршунов, Максим Михайлович; Eremin, I.; Drechsler, S. L.; Khasanov, R.; Amato, A.; Hamann-Borrero, J. E.; Leps, N.; Kondrat, A.; Behr, G.; Werner, J.; Buchner, B.
}
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15.

Effect of heterovalent substitution of rare-earth elements on the magnetic and transport properties of YBa2Cu3O7 / M. I. Petrov [et al.] // Phys. Solid State. - 2007. - Vol. 49, Is. 11. - P. 2047-2051, DOI 10.1134/S1063783407110054. - Cited References: 18 . - ISSN 1063-7834

РУБ Physics, Condensed Matter
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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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation

Доп.точки доступа:
Petrov, M. I.; Петров, Михаил Иванович; Balaev, D. A.; Балаев, Дмитрий Александрович; Gokhfel'd, Yu. S.; Гохфельд, Юлия Сергеевна; Dubrovskii, A. A.; Дубровский, Андрей Александрович; Shaikhutdinov, K. A.; Шайхутдинов, Кирилл Александрович
}
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16.

Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta / C. . Janowitz [et al.] // JETP Letters. - 2004. - Vol. 80, Is. 11. - P. 692-696, DOI 10.1134/1.1862796. - Cited References: 18 . - ISSN 0021-3640

РУБ Physics, Multidisciplinary
Рубрики:
ELECTRONIC-STRUCTURE
   APICAL OXYGEN
   MODEL
   SUPERCONDUCTIVITY
   ONSET
Аннотация: The experimental dispersion of the first removal state in the insulating Bi2Sr2Ca1 - xYxCu2O8 + delta regime is found to differ significantly from that of other parent materials: oxyclorides and La2CuO4. For Y contents of 0.92 greater than or equal to x greater than or equal to 0.55 due to nonstoichiometric effects in the Bi-O layers, the hole concentration in the CuO2 layers is almost constant and, on the contrary, the crystal lattice parameters a, b, c change very strongly. This (a, b) parameter increase and c parameter decrease results in an unconventional three peak structure at (0, 0), (pi/2, pi/2), (pi, pi) for x = 0.92. We can describe the experimental data only beyond the framework of the three-band p-d-model involving the representations of a new triplet counterpart for the Zhang-Rice singlet state. (C) 2004 MAIK "Nauka/Interperiodica".

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Держатели документа:
Humboldt Univ, Inst Phys, D-12489 Berlin, Germany
Russian Acad Sci, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
Institute of Physics, Humboldt University of Berlin, 12489 Berlin, Germany
Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Janowitz, C.; Seidel, U.; Unger, RST; Krapf, A.; Manzke, R.; Gavrichkov, V. A.; Гавричков, Владимир Александрович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич
}
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17.

Kuz'min, E. V.
Effect of frustrations on magnetism in the Ru double perovskite Sr2YRuO6 / E. V. Kuz'min, S. G. Ovchinnikov, D. J. Singh // Phys. Rev. B. - 2003. - Vol. 68, Is. 2. - Ст. 24409, DOI 10.1103/PhysRevB.68.024409. - Cited References: 24 . - ISSN 1098-0121

РУБ Physics, Condensed Matter
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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Держатели документа:
Krasnoyarsk State Univ, Krasnoyarsk 660074, Russia
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
USN, Res Lab, Ctr Computat Mat Sci, Washington, DC 20375 USA
ИФ СО РАН

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Singh, D. J.
}
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18.

Borisov, A. A.
Doping dependence of the band structure and chemical potential in cuprates by the generalized tight-binding method / A. A. Borisov, V. A. Gavrichkov, S. G. Ovchinnikov // Mod. Phys. Lett. B. - 2003. - Vol. 17, Is. 10-12. - P. 479-486, DOI 10.1142/S0217984903005500. - Cited References: 12 . - ISSN 0217-9849

РУБ Physics, Applied + Physics, Condensed Matter + Physics, Mathematical
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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Держатели документа:
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Krasnoyarsk State Univ, Theoret Phys Chair, Krasnoyarsk 660041, Russia
ИФ СО РАН

Доп.точки доступа:
Gavrichkov, V. A.; Гавричков, Владимир Александрович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; International Conference on Modern Problems in Superconductivity(3 ; 2002 ; Sept. ; 9-14 ; Yalta, Ukrain)
}
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19.

Aplesnin, S. S.
Quantum spin liquid in the 2D anisotropic Heisenberg model with frustrated next nearest neighbor exchange / S. S. Aplesnin // Low Temp. Phys. - 1998. - Vol. 24, Is. 8. - P. 572-577 ; Физика низких температур, DOI 10.1063/1.593639. - Cited References: 25 . - ISSN 1063-777X

РУБ Physics, Applied
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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Держатели документа:
Russian Acad Sci, LV Kirenskii Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович

}
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20.

Aplesnin, S. S.
Dimer state in the two-dimensional anisotropic alternated-exchange Heisenberg model / S. S. Aplesnin // Phys. Solid State. - 1998. - Vol. 40, Is. 6. - P. 986-990, DOI 10.1134/1.1130463. - Cited References: 14 . - ISSN 1063-7834

РУБ Physics, Condensed Matter
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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Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович
}
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