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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) : 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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Gavrichkov V. A., Korshunov M. M., Shneyder E. I.
Заглавие : Electron structure and electron-phonon interaction in the strongly correlated electron system of cuprates
Место публикации : Low Temp. Phys. - 2006. - Vol. 32, Is. 4-5. - P.483-488. - ISSN 1063-777X, DOI 10.1063/1.2199450; \b Физика низких температур
Примечания : Cited References: 37
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
HIGH-TC SUPERCONDUCTIVITY
C SUPERCONDUCTORS
J MODEL
BAND
REPRESENTATION
REGIME
OXIDES
Аннотация: The generalized tight-binding method presents a practical realization of the scheme that describes quasiparticles in a strongly correlated electron system and consists of exact intra-cell diagonalization of the model Hamiltonian and perturbative treatment of the inter-cell hoppings. In the present paper this method and its ab initio modification are applied to undoped and weakly doped HTSC cuprates. Results are in very good agreement with the experimental ARPES data on various compounds. Starting with a multiband p-d model the realistic effective low-energy Hamiltonian of strongly correlated electrons interacting with spin fluctuations and phonons is derived both for hole- and electron-doped systems. Without electron-phonon interaction the pure magnetic mechanism of pairing does not provide the correct value of T, even for single-layer La2-xSrxCuO4 and Nd2-xCexCuO4. (c) 2006 American Institute of Physics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaihutdinov K. A., Balaev D. A., Gokhfeld D. M., Popkov S. I., Petrov M. I.
Заглавие : Transport properties of HTSC-based composites: Modeling the random networks of Josephson weak links with magneto-active barriers.
Коллективы : NATO Advanced Research Workshop on Vortex Dynamics in High-Temperature Superconductors
Разночтения заглавия :авие SCOPUS: Transport properties of HTSC- based composites: Modeling the random networks of Josephson weak links with magneto-active barriers
Место публикации : J. Low Temp. Phys./ NATO Advanced Research Workshop on Vortex Dynamics in High-Temperature Superconductors (2002 ; May ; 17-22). - 2003. - Vol. 130, Is. 3-4. - P.347-381. - ISSN 0022-2291, DOI 10.1023/A:1022204705059
Примечания : Cited References: 89
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
HIGH-TEMPERATURE SUPERCONDUCTORS
SNS JUNCTIONS
THERMAL FLUCTUATIONS
RESISTIVE PROPERTIES
PERCOLATION SYSTEM
TRANSITION
YBA2CU3O7
BOUNDARY
OXIDES
Ключевые слова (''Своб.индексиров.''): crystalline materials--electric insulators--josephson junction devices--magnetic devices--magnetic barriers--superconducting materials--composite
Аннотация: The results of the study of transport properties (temperature dependences of resistivity and critical current, current-voltage characteristics) of two-phase composites on the basis of Y3/4Lu1/4Ba2Cu3O7 high-temperature superconductor (HTSC) produced by fast baking technique and modelling networks of Josephson-type weak links are reported. Non-superconducting ingredients with different magnetic structures, insulators and normal metals, function as barriers between HTSC crystallites. Besides strong suppression of superconducting properties in HTSC composites with magnetic barriers, anomalous behavior of temperature dependences of resistivity below T-c of HTSC grains have been observed and investigated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Zakharova E. V., Nekrasov I. A., Pchelkina Z. V., Ovchinnikov S. G.
Заглавие : The Fermi surface and the role of electronic correlations in Sm2-xCexCuO4
Коллективы :
Разночтения заглавия :авие SCOPUS: The Fermi surface and the role of electronic correlations in Sm 2-xCexCuO4
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2010. - Vol. 22, Is. 1. - Ст.15701. - ISSN 0953-8984, DOI 10.1088/0953-8984/22/1/015701
Примечания : Cited References: 35. - We would like to thank A A Kordyuk and I Eremin for useful discussions. The authors acknowledge support from RFBR (grants 08-02-00021, 10-02-00662, 08-02-91200 and 07-02-00226), the RAS programs on 'Low temperature quantum phenomena', 'Quantum physics of condensed matter' and 'Strongly correlated electrons solids', President of Russia (grants MK-614.2009.2 (IN) and MK-3227.2008.2 (ZP)), Scientific School (grant SS-1929.2008.2), Interdisciplinary UB-SB RAS project, Dynasty Foundation (ZP) and Russian Science Support Foundation (IN).
Предметные рубрики: T-C SUPERCONDUCTOR
IN-GAP STATES
SPIN CORRELATIONS
BAND
LA2-XSRXCUO4
EXCITATIONS
TRANSITION
EVOLUTION
SM2CUO4
OXIDES
Ключевые слова (''Своб.индексиров.''): antiferromagnetics--doping evolution--electron-doped--electronic correlation--emery model--experimental data--generalized tight bindings--high-t--hybrid scheme--magnetic orders--spin-liquid--tight binding model--two-regime--antiferromagnetism--cerium--cerium compounds--copper oxides--corundum--doping (additives)--fermi surface--fermions--tin--surfaces
Аннотация: Using a LDA + GTB (local density approximation + generalized tight-binding) hybrid scheme we investigate the band structure of the electron-doped high-T-c material Sm2-xCexCuO4. Parameters of the minimal tight-binding model for this system (the so-called three-band Emery model) were obtained within the NMTO (Nth-order muffin-tin orbital) method. The doping evolution of the dispersion and the Fermi surface in the presence of electronic correlations was investigated in two regimes of magnetic order: short-range (spin-liquid) and long-range (antiferromagnetic metal). Each regime is characterized by the specific topologies of the Fermi surfaces and we discuss their relation to recent experimental data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Korovushkin M. M.
Заглавие : Renormalization of Energy Structure and Oscillation Period in the de Haas-van Alphen Effect at the Strong Intersite Coulomb Interaction
Разночтения заглавия :авие SCOPUS: Renormalization of energy structure and oscillation period in the de Haas-van Alphen effect at the strong intersite Coulomb interaction
Место публикации : J. Phys. Soc. Jpn.: PHYSICAL SOC JAPAN, 2011. - Vol. 80, Is. 1. - Ст.14703. - С. P. - ISSN 0031-9015, DOI 10.1143/JPSJ.80.014703
Примечания : Cited References: 36. - This study was supported by the program "Quantum Physics of Condensed Matter'' of the Presidium of the Russian Academy of Sciences (RAS), the Russian Foundation for Basic Research (project No. 10-02-00251), the Federal goal-oriented program Scientific Brainpower of the Russian Innovations 2009-2013, and the Siberian Division of RAS (Interdisciplinary Integration project No. 53). One of the authors (M. K.) would like to acknowledge the support of the Lavrentiev's Competition of the Siberian Division of RAS. The authors are grateful to the Physical Society of Japan for financial support in publication.
Предметные рубрики: T-C SUPERCONDUCTOR
EXTENDED HUBBARD-MODEL
CUPRATE SUPERCONDUCTORS
ELECTRON CORRELATIONS
QUANTUM OSCILLATIONS
FERMI-SURFACE
OXIDES
TEMPERATURE
STATE
BANDS
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--cuprate superconductors--intersite coulomb interaction--t-v model--de haas-van alphen effect--cuprate superconductors--de haas-van alphen effect--intersite coulomb interaction--strongly correlated electron systems--t-v model
Аннотация: The effect of strong intersite Coulomb correlations on the formation of the electron structure of the t-V model has been studied. A qualitatively new result indicating the occurrence of a split-off band of Fermi states has been obtained. The spectral intensity of this band increases with an increase in doping level and is determined by the mean-square fluctuation of occupation numbers. This results in the transformation of the energy structure and the integrated density of states and in a further decrease in state occupation in the quasimomentum space near the Fermi level as compared with Hubbard renormalization. It has been shown that this effect leads to an increase in the area of the quasimomentum space part limited by the Fermi contour and is important for the analysis of the de Haas-van Alphen oscillations in cuprate superconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneider E. I.
Заглавие : Effective Hamiltonian for HTSC cuprates taking into account electron-phonon interaction in the strong-correlation regime
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 101, Is. 5. - P844-855. - ISSN 1063-7761, DOI 10.1134/1.2149064
Примечания : Cited References: 38. - This work was supported by the Russian Foundation for Basic Research (project no. 03-02-16124), the program “Quantum Macrophysics” of the Presidium of the Russian Academy of Sciences, the Foundation in Support for Russian Science, the Foundation of Noncommercial
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
D-WAVE SUPERCONDUCTIVITY
T-C
DISPERSION
SCATTERING
OXIDES
STATE
MODEL
Ключевые слова (''Своб.индексиров.''): electron beams--electronic structure--optimization--phonons--electron correlations--hubbard x operators--spin-photon interaction--hamiltonians
Аннотация: Electron-phonon interaction is sequentially derived from a realistic p-d multiband model for the cuprates under conditions of strong electron correlations. The electronic structure is described using the representation of the Hubbard X operators in a generalized tight-binding method. Dependences of the diagonal and off-diagonal (on lattice sites) matrix elements of electron-phonon interaction on the wavevectors are found for three phonon modes, namely, breathing, apical breathing, and bending modes. The interactions of the breathing and bending modes with electrons are shown to contribute to the formation of kinks in the (0; 0)-(pi; pi) and (0; 0)-(pi; 0) directions, respectively. A low-energy t-J* model with phonons is developed; apart from electron-phonon interaction, it also includes spin-phonon interaction. The elimination of phonons gives an effective electron-electron interaction that depends on the occupation number of a multielectron term and on the carrier concentration due to strong electron correlations. (c) 2005 Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Petrakovskii G. A., Bayukov O. A., Varnek V. A., Sokolov V. V., Bovina A. F.
Заглавие : Mossbauer studies of FexMn1-xS single crystals
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 2. - P237-240. - ISSN 1063-7834, DOI 10.1134/S1063783408020042
Примечания : Cited References: 16
Предметные рубрики: METAL-INSULATOR-TRANSITION
MAGNETIC-PROPERTIES
ALPHA-MNS
SULFIDES
MAGNETORESISTANCE
PRESSURE
SYSTEM
OXIDES
Аннотация: Single crystals of iron manganese sulfides FexMn1-xS (0.25
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Avramov P. V.
Заглавие : Effects of intense electron correlations on x-ray and x-ray electron copper spectra of high-temperature superconductors
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 37, Is. 9. - P.2559-2567. - ISSN 0367-3294
Примечания : Cited References: 22
Предметные рубрики: HIGH-ENERGY SPECTROSCOPY
HIGH-TC SUPERCONDUCTORS
SATELLITES
LA2CUO4
OXIDES
HOLES
STATE
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Effects of the intense electron correlations on the shape of x-ray CuK absorption spectra of La2-xSrxCuO4
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 108, Is. 4. - P.1479-1488. - ISSN 0044-4510
Примечания : Cited References: 28
Предметные рубрики: HIGH-TC SUPERCONDUCTIVITY
EDGE STRUCTURE
LA2CUO4
SATELLITES
ALPHA
EXCITATIONS
COPPER
OXIDES
STATE
SHAKE
WOS
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S. N., Dudnikov V. A., Shishkina N. N., Solovyov L. A.
Заглавие : Phase transformation behavior of Sr0.8Gd0.2CoO3-delta perovskite in the vicinity of order-disorder transition
Коллективы : Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund [16-43-240505 p_a, 16-02-00507A]
Место публикации : Thermochim. Acta: Elsevier Science, 2017. - Vol. 655. - P.34-41. - ISSN 0040-6031, DOI 10.10164/j.tca.2017.06.003. - ISSN 1872-762X(eISSN)
Примечания : Cited References:40. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research project #16-43-240505 p_a and #16-02-00507A.
Предметные рубрики: OXYGEN SORPTION
OXIDES
PERFORMANCE
DIFFUSE
LN
Ключевые слова (''Своб.индексиров.''): perovskite--ruddlesden-popper phase--order-disorder--phase transition--dsc
Аннотация: The phase transformation behavior of a single-phase tetragonal Sr0.8Gd0.2CoO3-δ (with ordered distribution of Sr2+/Gd3+ cations and anion vacancies) was investigated by TG–DSC and XRD at 1100–1473 K and oxygen partial pressure p(O2) from 1 to 5·104 Pa. The first-order smeared order-disorder (o-d) phase transition involving heat absorption was observed at about 1383 K under O2-Ar flow with p(O2) 2.5 kPa. The crystal structure of the high-temperature phase was found to be cubic perovskite with disordered Sr2+/Gd3+ cations and anion vacancies. The temperature of o-d transition at p(O2) 2.5 kPa was not influenced by the heating rate or oxygen partial pressure. It was shown that at p(O2) 2.5 kPa the o-d transition gives rise to Sr0.8Gd0.2CoO3−δ decomposition to form CoO and Sr2.4Gd0.6Co2O7-δ − Ruddlesden-Popper type phase with novel composition. The phase boundaries between the ordered tetragonal Sr0.8Gd0.2CoO3−δ, disordered cubic Sr0.8Gd0.2CoO3−δ and CoO + Sr2.4Gd0.6Co2O7-δ composite as a function of temperature and p(O2) values were determined.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Non-diagram transitions in polarized X-ray absorption CuL(3) spectra of HTSC-ceramics
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 38, Is. 11. - P3226-3240. - ISSN 0367-3294
Примечания : Cited References: 28
Предметные рубрики: HIGH-TC SUPERCONDUCTIVITY
LA2CUO4
ALPHA
SATELLITES
STATES
OXIDES
XANES
WOS
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Orlov Y. S., Ovchinnikov S. G.
Заглавие : Construction of a Multielectron Basis for Mott Insulators with Strong Electron Correlations, Spin-Orbit Interaction, and Covalence
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 2. - P.322-338. - ISSN 1063-7761, DOI 10.1134/S1063776109080196
Примечания : Cited References: 35
Предметные рубрики: NARROW ENERGY BANDS
MAGNETIC ANISOTROPY ENERGY
ORIGIN
TRANSITION
PHYSICS
MANGANITES
OXIDES
CHARGE
Аннотация: We propose that the apparatus of quantum mechanics of a free atom (in particular, the theory of nj symbols and Rakah-Wigner genealogic coefficients generalized to the case of point groups and widely used in crystal field theory) be used for constructing multielectron bases with allowance for covalence and spin-orbit interaction. This allows us to take into account the electron-electron interaction for 3d ions the most comprehensively. The basis constructed in this way can be used in the generalized strong coupling method for the multiband p-d model in describing the structure of the quasiparticle energy spectrum and physical properties of systems with strong electron correlations. The procedure of construction and computation is demonstrated for the (5)T(2g) term in the d(6) configuration of the transition metal atom in an octahedral field. The mechanism for the emergence of magnetic anisotropy in S ions (Fe(3+) and Mn(2+)) due to covalent mixing of d(6) (L) under bar configurations with a nonzero orbital angular momentum ((L) under bar is a hole in ligands) is demonstrated
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : OVCHINNIKOV S.G.
Заглавие : THE INFLUENCE OF THE ANTIFERROMAGNETISM ON THE ELECTRONIC-STRUCTURE OF LA2CUO4
Разночтения заглавия :авие SCOPUS: The influence of the antiferromagnetism on the electronic structure of La2CuO4
Место публикации : J. Supercond.: PLENUM PUBL CORP, 1995. - Vol. 8: University-of-Miami Workshop on High-Temperature Superconductivity - Physical Properties and Mechanisms (JAN 05-11, 1995, CORAL GABLES, FL), Is. 5. - P675-676. - ISSN 0896-1107, DOI 10.1007/BF00727473
Примечания : Cited References: 15
Предметные рубрики: OXIDES
MODEL
Ключевые слова (''Своб.индексиров.''): electron correlations--electron structure--spin fluctuations--electron correlations--electron structure--spin fluctuations--antiferromagnetism--band structure--calculations--correlation theory--electrons--lanthanum compounds--paramagnetism--perturbation techniques--antiferromagnetic phase--electron correlations--intercluster interactions--spin fluctuations--electronic structure
Аннотация: The quasiparticle approach for electronic structure calculations considering strong electron correlations is given. The exact diagonalization of a multiband Hubbard Hamiltonian for a small cluster is combined with perturbation theory for intercluster hopping. The band structure of paramagnetic and antiferromagnetic La2CuO4 are discussed.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Kuz'min E. V., Ovchinnikov S. G.
Заглавие : Electronic structure and order parameter symmetry in high-temperature superconductors
Место публикации : Uspekhi Fiz. Nauk: MEZHDUNARODNAYA KNIGA, 2000. - Vol. 170, Is. 2. - P.189-192. - ISSN 0042-1294
Примечания : Cited References: 31
Предметные рубрики: CORRELATED ELECTRONS
HUBBARD-MODEL
OXIDES
LA2-XSRXCUO4
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Ovchinnikov S. G., Gavriliuk A. G., Struzhkin V. V.
Заглавие : Spin-crossover-induced Mott transition and the other scenarios of metallization in 3d(n) metal compounds
Разночтения заглавия :авие SCOPUS: Spin-crossover-induced Mott transition and the other scenarios of metallization in 3 dn metal compounds
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2009. - Vol. 79, Is. 8. - Ст.85125. - ISSN 1098-0121, DOI 10.1103/PhysRevB.79.085125
Примечания : Cited References: 41
Предметные рубрики: RARE-EARTH ORTHOFERRITES
NARROW ENERGY BANDS
HIGH-PRESSURE
MAGNETIC COLLAPSE
ELECTRON CORRELATIONS
PHASE-TRANSITION
STATE
Y3FE5O12
OXIDES
EQUATION
Ключевые слова (''Своб.индексиров.''): bismuth compounds--hubbard model--localised states--metal-insulator transition--metallisation--spin systems
Аннотация: A different "Hubbard energy control" mechanism of the insulator-metal transition (IMT) in Mott-Hubbard insulators is discussed. This mechanism can be initiated by the lattice compression and it is driven by a spin crossover of 3d(5) ions from the high-spin state to the low-spin state. The spin crossover suppresses the effective Hubbard parameter U-eff down to the value enabling the insulator-metal transition according to the Mott mechanism U-eff/W approximate to 1. The classification of possible scenarios of metallization in the other 3d(n) metal compounds is also performed.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vereshchagin S. N., Solovyov L. A., Rabchevskii E. V., Dudnikov V. A., Ovchinnikov S. G., Anshits A. G.
Заглавие : Methane oxidation over A-site ordered and disordered Sr0.8Gd0.2CoO3−δ perovskites
Коллективы : SB RAS project [38]; RFBR [13-02-00358]
Место публикации : Chem. Commun.: Royal Society of Chemistry, 2014. - Vol. 50, Is. 46. - P.6112-6115. - ISSN 1359-7345, DOI 10.1039/c4cc00913d. - ISSN 1364-548X
Примечания : Cited References: 20. - The authors acknowledge the financial support from SB RAS project N 38 (2012) and RFBR grant 13-02-00358.
Предметные рубрики: MEMBRANE REACTORS
OXYGEN
OXIDES
PERFORMANCE
COMBUSTION
FEATURES
PHASES
Аннотация: A tetragonal phase Sr0.8Gd0.2CoO3−δ with ordered Gd3+/Sr2+ ions and oxygen vacancy sites is found to be about five times less active in the reaction of methane combustion than a quenched cubic perovskite phase with randomly distributed (disordered) Gd3+/Sr2+ ions over the A-sites of the crystal lattice.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Dudnikov V. A., Ovchinnikov S. G., Orlov Yu.S., Kazak N. V., Michel C. R., Patrin G. S., Yurkin G.Yu.
Заглавие : Contribution of Co3+ ions to the high-temperature magnetic and electrical properties of GdCoO3
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 114, Is. 5. - P.841-849. - ISSN 1063-7761, DOI 10.1134/S106377611203003X
Примечания : Cited References: 28. - This work was supported by the Ural Branch of the Russian Academy of Sciences and Siberian Branch of the Russian Academy of Sciences (project no. 40), the Russian Foundation for Basic Research (project nos. 09-02-00171-a, 10-02-00251), program 2.3 of the Department of Physical Sciences of Russian Academy of Sciences, and Nonprofit Dinastiya Foundation.
Предметные рубрики: SPIN-STATE
RCOO3 R
TRANSITIONS
COBALTITES
LACOO3
OXIDES
SM
EU
ND
Аннотация: The temperature dependence of the static magnetization of polycrystalline rare-earth cobaltite GdCoO3 is measured in the temperature range 2-800 K. The magnetic behaviors of GdCoO3 and Gd3+ are found to be different at temperatures above room temperature, which is caused by the appearance of a contribution from Co3+ ions at high temperatures. The temperature dependence of the magnetic susceptibility of GdCoO3 is determined by the magnetization of rare-earth gadolinium ions and the additional paramagnetic contribution induced by the thermally excited magnetic terms of Co3+ ions. The LDA + GTB method is used to calculate the electronic structure of GdCoO3 in the temperature range 0-300 K with allowance for strong electron correlations. The energy spectrum of GdCoO3 is found to have intragap states that decrease the dielectric gap width with increasing temperature.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kim J., Struzhkin V. V., Ovchinnikov S. G., Orlov Yu. S., Shvyd'ko Y., Upton M. H., Casa D., Gavriliuk A. G., Sinogeikin S. V.
Заглавие : Pressure-induced spin transition and evolution of the electronic excitations of FeBO3: Resonant inelastic x-ray scattering results
Коллективы : DOE [DE-FG02-02ER45955]; U.S. DOE [DE-AC02-06CH11357]; President of Russia Grants [NSh-1044.2012.2, MK-1168.2012.2]; Presidium of the Russian Academy of Sciences Program 2, RFFI [12-02-90410, 12-02-31543]; Siberian Federal University Grant [F11]; Russian Foundation for Basic Research grants from RAS programs [14-0200483, 15-02-03770]; FCP [GK-P891]
Место публикации : Europhys. Lett. - 2014. - Vol. 108, Is. 3. - Ст.37001. - ISSN 0295-5075, DOI 10.1209/0295-5075/108/37001. - ISSN 1286-4854
Примечания : Cited References: 47. - High-pressure work was supported by DOE under Contract No. DE-FG02-02ER45955. The use of the Advanced Photon Source at the Argonne National Laboratory was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. SGO and YuO acknowledge the President of Russia Grants NSh-1044.2012.2 and MK-1168.2012.2, the Presidium of the Russian Academy of Sciences Program 2, RFFI Grants 12-02-90410 and 12-02-31543, FCP GK-P891, and the Siberian Federal University Grant F11. AGG acknowledges support from the Russian Foundation for Basic Research grants 14-02-00483 and 15-02-03770 from RAS programs "Strongly correlated electron systems", "Elementary particle physics, fundamental nuclear physics and nuclear technologies".
Предметные рубрики: LOWER-MANTLE
SPECTRA
STATE
EMISSION
COLLAPSE
SYSTEMS
OXIDES
METAL
Аннотация: A high-pressure resonant inelastic x-ray scattering (RIXS) of FeBO3 at the Fe K pre-edge has been carried out to study the evolution of electronic excitations through the pressure-induced spin transition. Systematic peak shifts with insignificant peak width change are observed with increasing pressure in the high-spin state. An electronic transition occurs in tandem with the high-spin to low-spin transition, observed as the emergence of multiple new low-energy peaks in the spectra. The energy gap is reduced due to these low-energy peaks, not a peak width broadening. The observed electronic excitations are associated with dd excitations, which are calculated using a full-multiplet theory. We consider changes in crystal-field splitting and covalency to explain the observed peak shifts in the high-spin state. The new peaks that emerge upon the high- to low-spin transition are compared with dd excitations for the low-spin configuration. Copyright (C) EPLA, 2014
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyanchuk I. O., Bushinsky M. V., Sikolenko V., Efimov V., Volkov N. V., Tobbens D. M., Ritter C., Raveau B.
Заглавие : Ferromagnetism in single-valent manganites
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 619. - P.719-725. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.08.236. - ISSN 1873-4669
Примечания : Cited References: 46. - The authors would like to thank J.B. Goodenough for the fruitful discussion. This work has been supported by Belarusian Republican Foundation for Fundamental Research (Grant F14R-040).
Предметные рубрики: PHASE-SEPARATION
DOPED MANGANITES
DOUBLE EXCHANGE
DIFFRACTION
OXIDES
NMR
Ключевые слова (''Своб.индексиров.''): magnetically ordered materials--solid state reactions--exchange and superexchange--magnetic measurements--neutron diffraction
Аннотация: Structural and magnetization measurements have been performed on the La0.7Sr0.3Mn0.85 Nb 0.15 - x 5 + Mg x 2 + O3 stoichiometric compounds. With rise of the Mg2+ content the formal oxidation state manganese increases from +3 ( x = 0 ) up to +3.55 ( x = 0.15 ) . The compositions with 0 ⩽ x ≤ 0.08 undergo a structural transition from rhombohedral to orthorhombic symmetry below room temperature whereas x = 0.1 and x = 0.15 compounds are rhombohedral down to 2 K. The structural parameters evidence that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The Mg-free compound is ferromagnetic with the Curie point of around 150 K and a magnetic moment of 3.1 μ B /Mn. The substitution of Nb5+ with Mg2+ leads to a gradual weakening of the ferromagnetic component while in the x = 0.15 compound A-type antiferromagnetic short-range order is stabilized in spite of macroscopic R 3 ¯ c symmetry. All the compositions show insulating behavior. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder induced by Nb5+ and Mg2+ ions leads to suppression of ferromagnetism.
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