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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Rudenko V. V., Kazak N. V., Edelman I. S., Gavrichkov V. A.
Заглавие : Weak antiferromagnet iron borate FeBO3. classical object for magnetism and the state of the art
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : J. Exp. Theor. Phys. - 2020. - Vol. 131, Is. 1. - P.177-188. - ISSN 1063-7761, DOI 10.1134/S106377612007016X. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 74. - This work was supported by the Russian Science Foundation, project no. 18-12-00022
Предметные рубрики: ELECTRONIC-STRUCTURE
TRANSITION
RESONANCE
FERROMAGNETISM
DEPENDENCE
Аннотация: The simple lattice and magnetic structure, the high Neel temperature, the narrow antiferromagnetic resonance line of FeBO3, and the narrow electron paramagnetic resonance line of its isostructural diamagnetic analogs MBO3:Fe3+(M = Ga, In, Sc, Lu) make iron borate unique for investigations and applications. Iron borate is a model crystal for numerous experimental and theoretical studies, including spin crossovers and metallization at megabar pressures and many-electron effects in optics and X-ray spectroscopy. The recent works dealing with the investigation of the properties of FeBO(3)are reviewed.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V.
Заглавие : Spintronics: manganite-based magnetic tunnel structures
Место публикации : Phys. Usp.: Turpion LTD, 2012. - Vol. 55, Is. 3. - P.250-269. - ISSN 1063-7869, DOI 10.3367/UFNe.0182.201203b.0263
Примечания : Cited References: 91. - This work was supported by the Russian Foundation for Basic Research (grant No. 11-02-00367-a); the program of the Presidium of the RAS, Fundamental Research on Nanotechnologies and Nanomaterials (grant No. 21.1); the program of the Department of Physical Sciences of the RAS "Spin Phenomena in Solid Nanostructures and Spintronics" (grant No. 2.4.4.1); integration projects of the Siberian Branch, RAS, Nos 5 and 134; and the Federal Special Purpose Program "Scientific and Pedagogical Personnel of Innovative Russia" (state contract No. NK-556P_15).
Предметные рубрики: HIGH-FREQUENCY RECTIFICATION
THIN INSULATING FILM
COLOSSAL MAGNETORESISTANCE
GIANT MAGNETORESISTANCE
ELECTRONIC-STRUCTURE
SANDWICH STRUCTURES
SPIN POLARIZATION
IDENTICAL METALS
PHASE-SEPARATION
ROOM-TEMPERATURE
Аннотация: A topical and highly promising aspect of the field of spintronics is the physics involved in the flow of a spin-polarized current through magnetic tunnel structures. This review focuses on manganite-based structures, which are appealing for their high Curie temperature, highly spin-polarized conduction electrons, high chemical stability, and well-developed fabrication technology. Particular emphasis is placed on some novel approaches to studying the tunnel structures, including the use of planar geometry and the application of combined external factors (microwave and optical radiation) to investigate spin-polarized transport.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Varganov S. A., Avramov P. V., Ovchinnikov S. G.
Заглавие : Ab initio calculations of endo- and exohedral C-60 fullerene complexes with Li+ ion and the endohedral C-60 fullerene complex with Li-2 dimer
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 2. - P388-392. - ISSN 1063-7834, DOI 10.1134/1.1131218
Примечания : Cited References: 16
Предметные рубрики: ELECTRONIC-STRUCTURE
ENERGIES
C60
Аннотация: The results of ab initio Hartree-Fock calculations of endo- and exohedral C-60 fullerene complexes with the Li+ ion and Li-2 dimer are presented. The coordination of the Li+ ion and the Li-2 dimer in the endohedral complexes and the coordination of Li+ ion in the exohedral complex of C-60 fullerene are determined by the geometry optimization using the 3-21G basis set. In the endohedral Li+C60 complex, the Li+ ion is displaced from the center of the C-60 cage to the centers of carbon hexa- and pentagons by 0.12 nm. In the Li-2 dimer encapsulated inside the C-60 cage, the distance between the lithium atoms is 0.02 nm longer than that in the free molecule. The calculated total and partial one-electron densities of states of C-60 fullerene are in good agreement with the experimental photoelectron and X-ray emission spectra. Analysis of one-electron density of states of the endohedral Li+@C-60 complex indicates an ionic bonding between the Li atoms and the C-60 fullerene. In the Li+C60 and Li+@C-60 complexes, there is a strong electrostatic interaction between the Li+ ion and the fullerene. (C) 2000 MAIK "Nauka/Interperiodica".
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Togushova, Yu. N., Shestakov V. A., Korshunov M. M.
Заглавие : Impurity-induced smearing of the spin resonance peak in Fe-based superconductors
Коллективы : RFBR [13-02-01395]; President Grant for Government Support of the Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; Ministry of education and science of Russia [GF-2, SFU]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.481-487. - ISSN 0022-2291, DOI 10.1007/s10909-016-1577-x. - ISSN 1573-7357(eISSN)
Примечания : Cited References:25. - We acknowledge partial support by the RFBR (Grant 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), and The Ministry of education and science of Russia (GF-2, SFU).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
ELECTRONIC-STRUCTURE
IRON
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin resonance peak--spin-orbit coupling--impurity scattering
Аннотация: The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yelisseyev A. P., Molokeev M. S., Jiang, Xingxing, Krinitsin P. G., Isaenko L. I., Lin, Zheshuai
Заглавие : Structure and optical properties of the Li2In2GeSe6 crystal
Коллективы : Russian Foundation of Basic Research [15-02-03408a, 17-45-540775r_a, 17-52-53031]; National Scientific Foundations of China [11474292, 51702330, 11611530680, 91622118, 91622124]; special foundation of the director of Technical Institute of Physics and Chemistry (TIPC); China "863" project [2015AA034203]; Youth Innovation Promotion Association, CAS [2017035]; [0330-2016-0008]
Место публикации : J. Phys. Chem. C. - 2018. - Vol. 122, Is. 30. - P.17413-17422. - ISSN 1932-7447, DOI 10.1021/acs.jpcc.8b02799
Примечания : Cited References: 49. - This work was supported by state assignment project #0330-2016-0008 and partly by the Russian Foundation of Basic Research (grants nos. 15-02-03408a, 17-45-540775r_a, and 17-52-53031), National Scientific Foundations of China (grants 11474292, 51702330, 11611530680, 91622118, and 91622124), the special foundation of the director of Technical Institute of Physics and Chemistry (TIPC), the China "863" project (no. 2015AA034203), and the Youth Innovation Promotion Association, CAS (outstanding member for Z.L. and grant 2017035 for X.J.).
Предметные рубрики: PHASE-MATCHING PROPERTIES
TEMPERATURE-DEPENDENCE
ELECTRONIC-STRUCTURE
Аннотация: Intense search for new nonlinear optical crystals for the mid-infrared region is in progress, and Li-containing quaternary chalcogenides are expected to improve transparency range, stability, phase-matching conditions, and other parameters in comparison with commercially available AgGaS2, AgGaSe2, and ZnGeP2. Single crystals of Li2In2GeSe6 up to 8 mm in size were obtained by the Bridgman- Stockbarger growth technique, and their high quality was confirmed by exciton luminescence. A monoclinic structure and direct band-to-band electronic transitions were established, and the thermal expansion was shown to be virtually isotropic. Defect-related absorption and luminescence were revealed, and the way to lower them was suggested. The electronic structure, density of states, and some optical properties were calculated from the first principles for Li2In2GeSe6. The calculated nonlinear coefficients and rather large birefringence indicate a strong phase-matching ability. These investigations demonstrate that Li2In2GeSe6 is a promising mid-infrared nonlinear optical crystal.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Janowitz C., Seidel U., Unger RST, Krapf A., Manzke R., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta
Разночтения заглавия :авие SCOPUS: Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xY xCu2O8+δ
Место публикации : JETP Letters. - 2004. - Vol. 80, Is. 11. - P.692-696. - ISSN 0021-3640, DOI 10.1134/1.1862796
Примечания : Cited References: 18
Предметные 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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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Ovchinnikov S. G., Korshunov M. M., Eremin I. M., Kazak N. V.
Заглавие : Specific features of spin, charge, and orbital ordering in cobaltites
Коллективы : RFBR [09-02-00171-a, 07-02-00226, 09-02-00127]; Federal Agency of Science and Innovation [MK-4278.2008.2]; Presidium of the Russian Academy of Sciences [5, 7]; Leading Science Schools of the Ministry of Education and Science of the Russian Federation [2.1.1/3199]
Место публикации : Phys. Usp.: Turpion Ltd, 2009. - Vol. 52, Is. 8. - P.789-810. - ISSN 1063-7869, DOI 10.3367/UFNe.0179.200908b.0837
Примечания : Cited References: 278. - This work was financially supported by the RFBR (projects 09-02-00171-a, 07-02-00226, and 09-02-00127), the Federal Agency of Science and Innovation (grant MK-4278.2008.2), and the Presidium of the Russian Academy of Sciences Program No. 5, Quantum Physics of Condensed Media (project No. 7). I.M.E.'s work was supported by the program for Leading Science Schools of the Ministry of Education and Science of the Russian Federation (grant 2.1.1/3199).
Предметные рубрики: PEROVSKITE-TYPE OXIDES
METAL-INSULATOR-TRANSITION
HIGH-TEMPERATURE SUPERCONDUCTIVITY
ONE-DIMENSIONAL CA3CO2O6
ELECTRONIC-STRUCTURE
MAGNETIC-PROPERTIES
TRANSPORT-PROPERTIES
STATE TRANSITION
FUEL-CELLS
CRYSTAL-STRUCTURE
Ключевые слова (''Своб.индексиров.''): cobalt oxides--lanthanides--orbital degrees of freedom--orbital ordering--quasi-one-dimensional--spin state--superconducting compounds--theoretical result--calcium--cobalt--lanthanum--oxide minerals--perovskite--spin dynamics--superconductivity--cobalt compounds
Аннотация: Complex cobalt oxides known as cobaltites are reviewed, including LnCoO(3)-based perovskite-structured rare-earth cobaltites (where Ln is lanthanum or a lanthanide), quasi-two-dimensional and quasi-one-dimensional cobaltites of the types LnCo(2)O(5+delta), La2CoO4, and Ca3Co2O8, and NaxCoO2 center dot yH(2)O superconducting compounds. Key experimental and theoretical results are presented, with emphasis on the interplay between charge, spin, and orbital degrees of freedom. Two problems of specific relevance to cobaltites - the spin state instability of Co3+ ions in LnCoO(3), and the nature of superconductivity in NaxCoO2 center dot yH(2)O - are also given significant attention.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Beisel N. F., Galashov E. N., Mandrik E. M., Molokeev M. S., Yelisseyev A. P., Yusuf A. A., Xia Z.
Заглавие : Pressure-stimulated synthesis and luminescence properties of microcrystalline (Lu,Y)3Al5O12:Ce3+ garnet phosphors
Место публикации : ACS Appl. Mater. Interfaces: American Chemical Society, 2015. - Vol. 7, Is. 47. - P.26235-26243. - ISSN 19448244 (ISSN), DOI 10.1021/acsami.5b08411
Примечания : Cited References: 75. - This work was partly supported by the National Natural Science Foundations of China (Grant Nos. 51272242 and 51511130035) and the Russian Foundation for Basic Research (Grant No. 15-52-53080 GFEN_a). V.V.A. was partly supported by the Ministry of Education and Science of the Russian Federation
Предметные рубрики: LASER MASS-SPECTROMETRY
LIGHT-EMITTING-DIODES
WHITE-LIGHT
SINGLE-CRYSTALS
OPTICAL-PROPERTIES
ELECTRONIC-STRUCTURE
VIBRATIONAL PROPERTIES
PHASE-TRANSITIONS
PARTICLE-SIZE
GROWTH
Ключевые слова (''Своб.индексиров.''): synthesis--pressure--garnet--structure--luminescence--phosphor
Аннотация: The Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 phosphors were synthesized by solid state reaction at temperature 1623 K and pressure 1.5 × 107 Pa in (95% N2 + 5% H2) atmosphere. Under the conditions, the compounds crystallize in the form of isolated euhedral partly faceted microcrystals ∼19 μm in size. The crystal structures of the Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 garnets have been obtained by Rietveld analysis. The photoluminescence (PL) and X-ray excited luminescence (XL) spectra obtained at room temperature indicate broad asymmetric bands with maxima near 519 and 540 nm for Y2.99Ce0.01Al5O12 and Lu2.98Ce0.01Y0.01Al5O12, respectively. The light source was fabricated using the powder Lu2.98Ce0.01Y0.01Al5O12 phosphor and commercial blue-emitting n-UV LED chips (λex = 450 nm). It is found that the CIE chromaticity coordinates are (x = 0.388, y = 0.563) with the warm white light emission correlated color temperature (CCT) of 6400 K and good luminous efficiency of 110 lm/W. © 2015 American Chemical Society.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhlin Y. L., Vorobyev S., Saikova S. V., Tomashevich Y., Fetisova O., Kozlova S., Zharkov S. M.
Заглавие : Preparation and characterization of colloidal copper xanthate nanoparticles
Коллективы : Russian Science Foundation [14-17-00280]
Место публикации : New J. Chem.: Royal Society of Chemistry, 2016. - Vol. 40, Is. 4. - P.3059-3065. - ISSN 1144-0546, DOI 10.1039/c6nj00098c. - ISSN 1369-9261(eISSN)
Примечания : Cited References:50. - This research was supported by the Russian Science Foundation grant 14-17-00280. We thank Dr Roberto Felix Duarte (HZB) and bilateral program "German-Russian laboratory at BESSY II" for assistance with the X-ray absorption experiments.
Предметные рубрики: X-ray-absorption
Self-assembled monolayers
Sulfide nanoparticles
Electronic-structure
Waste-water
Complexes
Flotation
Spectroscopy
Adsorption
Oxidation
Аннотация: Despite the important role of metal xanthates in a number of industrial processes and emerging applications, no attempts have been made to prepare the metal xanthate nanoparticles and to study colloidal solutions of insoluble heavy metal xanthates. Here, we examined the formation of colloidal copper xanthate particles during the reactions of aqueous solutions of cupric sulfate and various potassium xanthates, which occur in flotation and water treatment slurries and can be used to manufacture nanoparticles for materials science (e.g., as precursors for copper sulfide nanoparticles and biomedicine). The products were characterized using UV-vis absorption, dynamic light scattering, zeta potential measurements, transmission electron microscopy (TEM), electron diffraction, Fourier transform infrared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XANES). Colloidal copper xanthates with compositions of ROCSSCu (R = ethyl, isopropyl, butyl, isobutyl, and amyl groups), disordered structures and average diameters of 20–80 nm easily formed and aggregated and were stable for at least several hours, especially if excessive xanthate was used. The hydrodynamic diameters of the nanoparticles were smaller at lower temperatures. Dixanthogens, which were produced in the reactions along with ROCSSCu, seemed to promote nanoparticle aggregation and precipitated with the copper xanthate, affecting their thermal decomposition. The TEM micrographs and S K- and Cu K-edge XANES spectra revealed core/shell particle morphologies, likely with Cu(I) bonded to four S atoms in the core and reduced copper coordination in the shell.
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10.

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

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Сomparison between the band structures of La2CuO4 and Nd2CuO4
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 102, Is. 1. - P.127-131. - ISSN 0044-4510
Примечания : Cited References: 6
Предметные рубрики: ELECTRONIC-STRUCTURE
Аннотация: The band structure of quasiparticles in undoped La2CuO4 and Nd2CuO4 dielectric compounds is calculated involving the strong electron correlations in the generalized tight-binding method. In both compounds the dielectric gap is determined mainly by the charge-transfer processes. The reduction of the gap during the La-to-Nd transition is described by decreasing the parameter delta=epsilon(p)-epsilon(d) under the fixed other parameters of the theory, epsilon(p) and epsilon(d) being the energies of the single-particle states of p- and d-holes.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Symmetry of holes in high-temperature superconductors
Место публикации : Solid State Commun. - 1991. - Vol. 77, Is. 3. - P.221-224. - ISSN 0038-1098, DOI 10.1016/0038-1098(91)90336-T
Примечания : Cited References: 19
Предметные рубрики: FERMI-LIQUID STATES
X-RAY ABSORPTION
ELECTRONIC-STRUCTURE
PHOTOEMISSION
BI2SR2CACU2O8
BISMUTH
Аннотация: A symmetry of holes is investigated in the multielectron band theory which takes into account strong correlations. It is shown that a small number of d(z2) states appears near the Fermi level due to d(z2) Cu-2p(x(y))O charge transfer as admixture to d(x2-y2)-p(x(y)) bands with dominant contribution of O2p states. The results are in a qualitative agreement with polarized photoemission data.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Modification of magnetic and superconducting properties of layered cuprates due to copper substitution for zinc and nickel
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 37, Is. 12. - P3645-3654. - ISSN 0367-3294
Примечания : Cited References: 28
Предметные рубрики: ELECTRONIC-STRUCTURE
LA2CUO4
LA2-XSRXCUO4
EXCITATIONS
DENSITY
PLANE
NI
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : OVCHINNIKOV S. G.
Заглавие : EFFECT OF SUBSTITUTIONAL IMPURITY SPECIES ON THE SUPPRESSION OF MAGNETIC-PROPERTIES OF WEAKLY DOPED COPPER OXIDES
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 5. - P1307-1310. - ISSN 0367-3294
Примечания : Cited References: 16
Предметные рубрики: ELECTRONIC-STRUCTURE
SUPERCONDUCTIVITY
LA2CUO4
EXCITATIONS
SPECTRA
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Effect of spin crossovers on the Mott-Hubbard transition at high pressures
Коллективы :
Место публикации : J. Exp. Theor. Phys.: Maik Nauka/Interperiodica/Springer, 2008. - Vol. 107, Is. 1. - P140-146. - ISSN 1063-7761, DOI 10.1134/S1063776108070145
Примечания : Cited References: 19. - The author is grateful to D. Homsky, G. Sawatzky, and M. Haverkort for fruitful discussions of results. This study was supported by the Russdian Foundation for Basic Research ( project no. 07-02-00226) and the Presidium of the Russian Academy of Sciences ( Program "Quantum Macrophysics"). This study was initiated during the author's work at the Kavli Institute for Theoretical Physics (University of California, Santa Barbara, USA) and supported by the NSF ( grant no. PHY05-51164).
Предметные рубрики: NARROW ENERGY BANDS
ELECTRONIC-STRUCTURE
MAGNETIC COLLAPSE
METAL COMPOUNDS
FEBO3
SPECTRA
GAPS
Ключевые слова (''Своб.индексиров.''): high pressures--mott hubbard transitions--spin crossovers--spin dynamics
Аннотация: The effect of spin crossovers in d (n) terms on the effective Hubbardparameter (U(eff)) determining the gap between the lower and upper Hubbard bands is analyzed using a many-electron approach to describe the electron structure of Mott insulators. A new mechanism of the insulator-metal transition is established for d(5) ions, which is related to a decrease in U(eff) caused by spin crossover. For other ions, the U (eff) value is either independent of pressure (d(2), d(4), d(7)) or it exhibits nonmonotonic growth (d(3), d(6), d(8)).
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : EFFECT OF ANTIFERROMAGNETIC ORDERING ON ZONE STRUCTURE OF LA2CUO4
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 107, Is. 3. - P796-811. - ISSN 0044-4510
Примечания : Cited References: 42
Предметные рубрики: HIGH-TC SUPERCONDUCTORS
ELECTRONIC-STRUCTURE
OXIDE SUPERCONDUCTORS
CHARGE-TRANSFER
CUO2 PLANE
MODEL
HOLE
SPECTRUM
STATE
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavriliuk A. G., Kharlamova S. A., Lyubutin I. S., Ovchinnikov S. G., Potseluyko A. M., Trojan I. A., Zabluda V. N.
Заглавие : Optical transitions in GdFe3(BO3)(4) and FeBO3 under high pressures
Разночтения заглавия :авие SCOPUS: Optical transitions in GdFe3(BO3)4 and FeBO3 under high pressures
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2005. - Vol. 17: 2nd International Symposium on Physics of Solids Under High Presure Using Nuclear Probes (JUL 22-25, 2004, Cologne, GERMANY), Is. 48. - P7599-7604. - ISSN 0953-8984, DOI 10.1088/0953-8984/17/48/011
Примечания : Cited References: 8
Предметные рубрики: ELECTRONIC-STRUCTURE
Ключевые слова (''Своб.индексиров.''): band structure--coulomb blockade--high pressure effects--iron compounds--magnetic moments--mathematical models--optical properties--relaxation processes--coulomb correlations--electron correlations--insulator-semiconductor transitions--optical transitions--gadolinium compounds
Аннотация: The optical properties of GdFe3(BO3)(4) under high pressures have been investigated experimentally and theoretically, and the results are compared with the properties of FeBO3. A model of the GdFe3(BO3)(4) band structure is derived within the multielectron model taking into account the strong electron correlations. Crossover of the Fe3+ ion high-spin and low-spin states, collapse of the magnetic moment, the relaxation Coulomb correlations, and insulator-semiconductor transition are predicted. Optical transitions in GdFe3(BO3)(4) and FeBO3 under high pressures were discovered.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Malakhovskii A. V., Sukhachev A. L., Vasil'ev A. D., Leont'ev A. A., Kartashev A. V., Temerov V. L., Gudim, I. A.
Заглавие : Nature of optical properties of GdFe3(BO3)4 and GdFe2.1Ga0.9(BO3)4 crystals and other 3d5 antiferromagnets
Место публикации : Eur. Phys. J. B: Springer, 2012. - Vol. 85, Is. 2. - P.80. - ISSN 1434-6028, DOI 10.1140/epjb/e2012-20953-1
Примечания : Cited References: 70. - The work was supported by the Russian Foundation for Basic Researches Grant 12-02-00026 and by Russian President Grant NSh-1044.2012.2.
Предметные рубрики: IRON BORATE GDFE3(BO3)4
D-D TRANSITIONS
EARTH FERROBORATES RFE3(BO3)4
ABSORPTION-SPECTRA
OCTAHEDRAL COMPLEXES
ELECTRONIC-STRUCTURE
NEEL TEMPERATURE
FINE-STRUCTURE
EXCHANGE
IONS
Аннотация: Influence of the partial substitution of paramagnetic Fe3+ ions by diamagnetic Ga3+ ions in the trigonal crystal GdFe3 (BO3)4 on its optical and magnetic properties is studied and discussed in connection with problems common for all antiferromagnets containing 3d 5 ions. Polarized optical absorption spectra and linear birefringence of GdFe3 (BO3)4 and GdFe2.1Ga0.9 (BO3)4 single crystals have been measured in the temperature range 85–293 K. Specific heat temperature dependence (2–300 K) and structure of GdFe2.1Ga0.9 (BO3)4 crystal have been also studied. As a result of substitution of 30% Fe to Ga the Neel temperature diminishes from 38 till 16 K, the strong absorption band edge shifts on 860 cm-1 (0.11 eV) to higher energy and the d-d transitions intensity decreases substantially larger than the Fe concentration does. Strong absorption band edge is shown to be due to Mott-Hubbard transitions. Correlation between position of the strong absorption band edge and the Neel temperature of antiferromagnets has been revealed. Properties of the doubly forbidden d-d transitions in the studied crystals and in other antiferromagnets are explained within the framework of the model of the exchange-vibronic pair absorption, which is theoretically analyzed in detail. The model permitted us to determine the connection between parameters of d-d absorption bands (intensity, width and their temperature dependences), on the one hand, and the exchange, spin-orbit and electron-lattice interactions, on the other hand.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mitskan V. A., Korovushkin M. M., Dzebisashvili D. M.
Заглавие : Implementation of the concept of spin polaron in cuprate superconductors within the diagram technique
Место публикации : JETP Letters. - 2021. - Vol. 114, Is. 5. - P.289-295. - ISSN 0021-3640, DOI 10.1134/S0021364021170094. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 43. - This work was supported by the Russian Foundation for Basic Research, project nos. 18-02-00837 and 20-32-70059
Предметные рубрики: ELECTRONIC-STRUCTURE
ELEMENTARY EXCITATIONS
QUASI-PARTICLES
Аннотация: The spectral properties of an ensemble of spin-polaron quasiparticles have been studied within the spin–fermion model of cuprate superconductors using the method combining the Feynman diagram technique and the diagram technique for spin operators. It has been shown that strong spin–charge coupling results in the formation of the lower spin-polaron band separated by a wide energy gap from the band of bare holes. It has been shown that the spin-polaron band has a local minimum near the (π/2, π/2) point of the Brillouin zone. A class of diagrams for the self-energy part that have a fundamental significance for the description of the main features of the spin-polaron spectrum has been determined.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev A. D., Bayukov O. A., Vasil'ev A. D., Velikanov D. A., Ivanova N. B., Kazak N. V., Ovchinnikov S. G., Abd-Elmeguid M. M., Rudenko V. V.
Заглавие : Magnetic and electrical properties of Fe1.91V0.09BO4 warwickite
Разночтения заглавия :авие SCOPUS: Magnetic and electrical properties of Fe1.91V 0.09BO4 warwickite
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 5. - P989-995. - ISSN 1063-7761, DOI 10.1134/1.1633954
Примечания : Cited References: 22. - This study was supported in part by the Russian Foundation for Basic Research (project no. 03-02-16286) and by the Federal Program “Integration” (project no. B0017)
Предметные рубрики: ELECTRONIC-STRUCTURE
CRYSTAL-STRUCTURE
FE2OBO3
CHAINS
FE2BO4
FEBO3
Ключевые слова (''Своб.индексиров.''): electric conductivity--magnetic variables measurement--magnetization--single crystals--hopping conductivity--warwickite--iron compounds
Аннотация: We have performed a complex investigation of the structure and the magnetic and electrical properties of a warwickite single crystal with the composition Fe1.91V0.09BO4 . The results of Mossbauer measurements at T = 300 K indicate that there exist "localized" (Fe2+, Fe3+) and "delocalized" (Fe2.5+) states distributed over two crystallographically nonequivalent positions. The results of magnetic measurements show that warwickite is a P-type ferrimagnet below T = 130 K. The material exhibits hopping conductivity involving strongly interacting electrons. The experimental data are analyzed in comparison to the properties of the initial (unsubstituted) Fe2BO4 warwickite. The entire body of data on the electric conductivity and magnetization are interpreted on a qualitative basis. (C) 2003 MAIK "Nauka / Interperiodica".
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