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

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Boehm M., Roessli B., Schefer J., Ouladdiaf B., Amato A., Baines C., Staub U., Petrakovskii G. A.
Заглавие : A neutron scattering and mu SR investigation of the magnetic phase transitions of CuB2O4
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2002. - Vol. 318: 6th Patras-University Euroconference on Properties of Condensed Matter Probed with X-Ray Scattering-Electron Correlations and Magnetism (SEP 21-25, 2001, PATRAS, GREECE), Is. 4. - P277-281. - ISSN 0921-4526, DOI 10.1016/S0921-4526(02)00788-3
Примечания : Cited References: 8
Предметные рубрики: COPPER METABORATE
Ключевые слова (''Своб.индексиров.''): magnetic soliton lattice--dzyaloshinskii-moriya interaction--neutron diffraction--mu sr
Аннотация: We have investigated the magnetic ground state in CuB2O4, copper metaborate, by means of neutron diffraction and muSR measurements. At T-N = 21 K CuB2O4 undergoes a second-order phase transition from a paramagnetic to an antiferromagnetic commensurate state followed by a second transition at T* = 10 K where the two magnetic sublattices form a soliton lattice, as reported earlier. We give a detailed analysis of the magnetic structure in the commensurate phase which is found to be different from the one published recently. New experimental results are presented which show the existence of a third transition below T approximate to 1.8 K. The magnetic structure remains incommensurate at very low temperatures, but a re-distribution of the magnetic intensities is observed in the neutron diffraction data set which suggests that the phases between the Cu2+ spins are changed. (C) 2002 Elsevier Science B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gerasimova Y. V., Krylov A. S., Vtyurin A. N., Laptash N. M., Goryainov S. V.
Заглавие : A Raman scattering study of the phase transition in the ammonium oxyfluoride (NH4)(3)TiOF5
Разночтения заглавия :авие SCOPUS: A raman scattering study of the phase transition in the ammonium oxyfluoride (NH4)3TiOF5
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 8. - P1534-1537. - ISSN 1063-7834, DOI 10.1134/S1063783408080246
Примечания : Cited References: 8
Предметные рубрики: (NH4)(3)WO3F3 OXYFLUORIDE
Аннотация: Raman spectra of a polycrystalline sample of the perovskite-like oxyfluoride (NH4)(3)TiOF5 are measured in the frequency region 100-3600 cm(-1) at temperatures ranging from 91 to 370 K under hydrostatic pressures of up to 9 GPa, which include the range of the phase transition from the orientationally disordered cubic phase to the low-symmetry phase. Anomalies in the spectral parameters due to the phase transition are revealed in the range of vibrations of TiOF5 octahedral groups.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Gerasimova J. V., Vtyurin A. N., Fokina V. D., Laptash N. M., Voyt E. I.
Заглавие : A study of phase transition in (NH4)(3)WO3F3 oxyfluoride by Raman scattering
Разночтения заглавия :авие SCOPUS: A study of phase transition in (NH4)3WO 3F3 oxyfluoride by Raman scattering
Место публикации : Phys. Status Solidi B. - 2006. - Vol. 243, Is. 2. - P.435-441. - ISSN 0370-1972, DOI 10.1002/pssb.200541259
Примечания : Cited References: 11
Предметные рубрики: ELPASOLITE RB2KSCF6
Аннотация: Raman scattering spectra of perovskite-like (NH4)(3)WO3F3 oxyfluoride are studied in the 70-3600 cm(-1) frequency range and the 93-323 K temperature range including the transition point from orientationally disordered cubic phase into the lower symmetry one. Internal vibrations of ammonium ions and WO3F3 octahedra have been found to exhibit transition anomalies. Analysis of measurements suggests that the transition under study is due mainly to the ordering of octahedra.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Bartolome J.
Заглавие : Structural distortions in families of perovskite-like crystals
Место публикации : Phase Transit.: TAYLOR & FRANCIS LTD, 2001. - Vol. 74, Is. 3. - P.255-335. - ISSN 0141-1594, DOI 10.1080/01411590108228754
Примечания : Cited References: 262
Предметные рубрики: LOW-TEMPERATURE PHASE
INELASTIC-NEUTRON-SCATTERING
POWDER PROFILE REFINEMENT
MII = CO
X-RAY
RAMAN-SCATTERING
ORDERED PEROVSKITE
RHOMBOHEDRAL PEROVSKITES
RB2KMIIIF6 ELPASOLITES
MAGNETIC-PROPERTIES
Ключевые слова (''Своб.индексиров.''): structural phase transitions--perovskites--perovskite-like crystals--group theoretical classification
Аннотация: The crystallographic and group theoretical analysis of the structural phase transitions in perovskite and perovskite-like crystals is reviewed. We include ABX(3) perovskites and their relative crystals of ReO3 type (G(0) = O-h(1)), elpasolites, cryolites and their relatives (G(0) = O-h(5)) layered crystals of TIAIF(4) series (G(0) = D-4h(1)), Aurivillius and Ruddlesden-Popper series (G(0) = D-4h(17)). The structures in their initial phase G(0) often contain n layers (n = 1, 2,3) of vertex linked octahedra. The distorted phases produced by one kind of tilt and by superposition of tilts in the slabs are enumerated. Most of the tilts correspond to symmetry changes, which can be associated to definite librational lattice modes irreducible representations of the G(0) group. The softening of modes associated to the PT has been found experimentally in many perovskites, elpasolites and layered crystals with n = 1. In contrast, no such soft modes have been found yet for even-layered (n = 2) crystals. Examples of successive phase transitions due to the superposition of tilts in these types of crystals have been collected.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorob’ev S. A., Burdakova E. A., Sarycheva A. A., Volochaev M. N., Karacharov A. A., Likhatskii M. N., Mikhlin Y. L.
Заглавие : Analysis of function of copper sulfide nanoparticles as sphalerite flotation activator
Место публикации : J. Min. Sci. - 2021. - Vol. 57, Is. 1. - P.144-153. - ISSN 10627391 (ISSN), DOI 10.1134/S1062739121010154
Примечания : Cited References: 22. - This study was supported by the Russian Science Foundation, project no. 18-17-00135
Аннотация: The authors compare the effect exerted by copper ions and sulphide copper nanoparticles on flotation of Gorevka deposit sphalerite using potassium n-butyl xanthate and in reagent-less regime. Covelline-like colloid particles 4–8 nm in size, obtained in interaction of copper (II) and sulfide ions in aqueous solutions, are characterized using the methods of dynamic light scattering, electron microscopy and diffraction. Sphalerite surface after reaction with copper ions and CuS dispersoid solutions are described by zeta-potential measurements and X-ray photoelectron spectroscopy. It is found that sphalerite flotation after activation with nanoparticles is lower than with copper ion solutions of the same concentrations, and improves with increasing duration of activation and flotation processes. The mechanism of CuS nanoparticles consists in creation of active centers for the collector to attach to, which intensifies the hydrophobic behavior and adsorption of the collector. Moreover, CuS nanoparticles promote formation of a special microrelief of the solid–liquid interface, which ensures rupture of liquid film and attachment of sphalerite particles to air bubbles when they collide.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovkina E. V., Krylova S. N., Vtyurin A. N., Krylov A. S.
Заглавие : Analyzing the symmetry of the Raman spectra of crystals according to angular dependences
Колич.характеристики :6 с
Место публикации : Bull. Russ. Acad. Sci. Phys. - 2024. - Vol. 88, Is. 5. - P.773-778. - ISSN 10628738 (ISSN), DOI 10.1134/S1062873824706573. - ISSN 19349432 (eISSN)
Примечания : Cited References: 32. - This work was supported by the Russian Foundation for Basic Research, project no. 21-52-12018. The authors are grateful to Dr. Irena Senkovska for providing our DUT-8(Ni) samples
Аннотация: The authors propose a way of reconstructing the Raman tensor by studying the angular dependences of the intensities of the Raman lines of unoriented microcrystals. The technique is verified using familiar calomel Hg2Cl2 crystals. It is shown that the lines on DUT-8 (Ni) crystals indicating phases with open and closed pores have different types of symmetries. The technique can be used to reconstruct the Raman tensor for any unoriented crystalline sample.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd D. M., Shaikhutdinov K. A.
Заглавие : Andreev reflection in natural grain boundaries of polycrystalline high-T-c superconductor La1.85Sr0.15CuO4
Разночтения заглавия :авие SCOPUS: Andreev reflection in natural grain boundaries of polycrystalline high-Tc superconductor La1.85Sr0.15CuO 4
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 7. - P1219-1222. - ISSN 1063-7834, DOI 10.1134/1.1594233
Примечания : Cited References: 30
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK LINKS
CHARGE-TRANSPORT
JUNCTIONS
CONDUCTIVITY
HYSTERESIS
COMPOSITES
SCATTERING
Аннотация: The temperature evolution of the current-voltage characteristic (CVC) of a "break junction" with metal-type conductivity on the polycrystalline La1.85Sr0.15CuO4 high-temperature superconductor is investigated. The CVC exhibits gap peculiarities and hysteresis, which is observed in the region of negative differential resistance. The experimental results are described well in terms of the Kummel-Gunsenheimer-Nicolsky theory for an S-N-S junction (S is a superconductor, N is a normal metal) this theory takes into account multiple Andreev reflection of quasiparticles. It is shown that the shape of the CVC and the existence and the shape of hysteresis are determined by the ratio of "long" and "short" grain boundaries in the polycrystal under investigation. (C) 2003 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Gokhfeld D. M., Balaev D. A., Shaihutdinov K. A., Kummel R.
Заглавие : Andreev reflections and experimental current-voltage characteristics of break junctions of polycrystalline HTSC
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2004. - Vol. 408: 7th International Conference on Materials and Mechanisms of Superconductive and High Temperature Superconductors (MAY 25-30, 2003, Rio de Janeiro, BRAZIL). - P620-622. - ISSN 0921-4534, DOI 10.1016/j.physc.2004.03.085
Примечания : Cited References: 3
Ключевые слова (''Своб.индексиров.''): andreev reflections--break junction--current-voltage characteristics--andreev reflections--break junction--current-voltage characteristics--andreev reflections--break junctions--elastic scattering--lattice defects--negative differential resistance--electric fields--heuristic methods--hysteresis--microcracks--polycrystalline materials--probability density function--quasicrystals--superconducting materials--yttrium barium copper oxides--current voltage characteristics
Аннотация: The temperature evolution of current-voltage characteristics (CVCs) of break junctions made from polycrystalline Y0.75Lu0.25Ba2Cu3O7 and La1.85Sr0.15CuO4 is investigated. The experimental CVCs have hysteretic features that reflect a part of a curve with negative differential resistance. The temperature evolution of the CVCs is discussed within the framework of the Kummel-Gunsenheimer-Nicolsky theory for superconductor/normal-metal/superconductor junctions considering multiple Andreev reflections. It is shown that the shape of the CVCs of break junctions is determined by the ratio of the number of "short" and "long" intergrain normal regions in the polycrystalline HTSC under investigation. (C) 2004 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pugachev A. M., Zaytseva I. V., Surovtsev N. V., Krylov A. S.
Заглавие : Anharmonicity and local noncentrosymmetric regions in BaTiO3 pressed powder studied by the Raman line temperature dependence
Место публикации : Ceram. Int. - 2020. - Vol. 46, Is. 14. - P.22619-22623. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2020.06.024
Примечания : Cited References: 26. - The reported study was funded by RFBR , according to the research project No. 18-02-00399 and 19-42-543-016 , Government of Novosibirsk region No. 19-42-543-016 and State assignment No AAAA-A17-117052410033-9. The experiments were performed in the multiple-access center “High-Resolution Spectroscopy of Gases and Condensed Matter” in IA&E SB RAS (Novosibirsk, Russia) and Center for Common Use of the Krasnoyarsk Scientific Center, SB RAS (Krasnoyarsk, Russia)
Аннотация: The temperature dependencies of position, width, and integral amplitude the E(TO) line near 307 cm−1 in Raman spectra in barium titanate powders with different non-hydrostatic pressure and temperature treatment were studied. It was found that parameters of the E(TO) line near 307 cm−1 are different in the crystal, the untreated powder, the powder treated by the non-hydrostatic pressure, and the powder annealed after the pressure treatment. The line width (FWHM) increase with temperature according to Klemens model. It indicates that the origin of the line broadening is the anharmonicity of the E(TO) phonons. The pressure treatment changes the anharmonicity of the phonon potential. It was found that the temperature dependence of the integral intensity of the E(TO) line is similar to that of the second optical harmonic signal and reflects the presence of the local polar regions. Thus, the E(TO) line in the Raman spectrum allows one to characterize the average polarity of local regions and their anharmonicity depending on non-hydrostatic pressures and thermal treatment.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kemper A. F., Korshunov M. M., Devereaux T. P., Fry J. N., Cheng H. P., Hirschfeld P. J.
Заглавие : Anisotropic quasiparticle lifetimes in Fe-based superconductors
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2011. - Vol. 83, Is. 18. - Ст.184516. - ISSN 1098-0121, DOI 10.1103/PhysRevB.83.184516
Примечания : Cited References: 43. - We thank O. Dolgov, R. Hackl, D. Maslov, I. Mazin, B. Muschler, V. Mishra, and J. Schmalian for useful discussions. A. F. K. and T. P. D. thank the Walther MeiBner Institut for their hospitality. A. F. K., M. M. K., and P. J. H. acknowledge support from DOE Grant No. DE-FG02-05ER46236. M. M. K. acknowledges support from RFBR (Grant No. 09-02-00127), Presidium of RAS program "Quantum physics of condensed matter" N5.7, FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK P891), and President of Russia (Grant No. MK-1683.2010.2). A. F. K. and T. P. D. acknowledge support from DOE Grant No. DE-AC02-76SF00515. H.-P. C. and J.N.F. acknowledge DOE/BES Grant No. DE-FG02-02ER45995.
Предметные рубрики: ELECTRONIC RAMAN-SCATTERING
Аннотация: We study the dynamical quasiparticle scattering by spin and charge fluctuations in Fe-based pnictides within a five-orbital model with on-site interactions. The leading contribution to the scattering rate is calculated from the second-order diagrams with the polarization operator calculated in the random-phase approximation. We find one-particle scattering rates which are highly anisotropic on each Fermi surface sheet due to the momentum dependence of the spin susceptibility and the multiorbital composition of each Fermi pocket. This fact, combined with the anisotropy of the effective mass, produces disparity between electrons and holes in conductivity, the Hall coefficient, and the Raman initial slope, in qualitative agreement with experimental data.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cao G. X., Korshunov M. M., Gao Y. Z., Le Tacon M., Singh D. J., Lin C. T.
Заглавие : Anomalous in-plane electronic scattering in charge ordered Na 0.41CoO 2•0.6H 2O
Место публикации : Phys. Rev. Lett.: American Physical Society, 2012. - Vol. 108, Is. 23. - Ст.236401. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.108.236401
Примечания : Cited References: 41. - We thank H. Habermeier, D. Mandrus, B. C. Sales, I. Eremin, I. I. Mazin, and P. J. Hirschfeld for useful discussions. G. Cao acknowledges support from NSFC (No. 10804068, 10774097). M. M. K. acknowledges support from RFBR (Grant No. 09-02-00127), Presisium of RAS program "Quantum physics of condensed matter" N5.7, Integration Grant of SBRAS-UrBRAS N40, and Russian FCP (GK 16.740.12.0731), and The Dynasty Foundation and ICFPM. Work at ORNL was supported by the Department of Energy, BES, Materials Science and Engineering Division.
Предметные рубрики: SUPERCONDUCTIVITY
TRIPLET
FLUCTUATIONS
IONS
Аннотация: We report electronic transport measurements on high quality floating zone grown NaxCoO2 and Na0.41CoO2·0.6H2O single crystals. We find an in-plane electronic scattering minimum near 11 K and a clear charge ordering at approximately 50 K. The electronic and magnetic properties in hydrated and nonhydrated Na0.41CoO2 samples are similar at higher temperature, but evolve in markedly different ways below ∼50 K, where a strong ferromagnetic tendency is observed in the hydrated sample. Model calculations show the relationship of this tendency to the structure of the Fermi surface. The results, particularly the clear differences between the hydrated and nonhydrated material show a substantially enhanced ferromagnetic tendency upon hydration. Implications for superconductivity are discussed.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the magnetic properties of weakly interacting antiferromagnetic chains with an alternating exchange interaction with spin S=1/2
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2000. - Vol. 90, Is. 1. - P194-201. - ISSN 1063-7761, DOI 10.1134/1.559075
Примечания : Cited References: 35
Предметные рубрики: PEIERLS COMPOUND CUGEO3
MAGNON DISPERSION
BI2CUO4
EXCITATIONS
RESONANCE
SYSTEMS
SCATTERING
DYNAMICS
NEUTRON
PHASE
Аннотация: An approximation dependence of the spontaneous magnetic moment at a site, sigma/sigma(0) - 1 = 0.71(6)delta(2.5(2)), and the antiferromagnet-singlet state phase boundary, J(2)/J(1) = 0.52(3)delta, are determined by the quantum Monte Carlo method in the self-consistent sublattice molecular field approximation for weakly interacting (J(2)) antiferromagnetic chains with spin S = 1/2 and alternating exchange interaction (J(1) +/- delta). The Neel temperature and a number of critical temperatures which could be related with the filling energy of two singlets (Delta S-z = 0) and one triplet (Delta S-z= 1) spin bands, each of which is split by the sublattice field (h(x,y)not equal h(z)) into two subbands, are determined on the basis of the computed correlation radii of the two- and four-spin correlation function, the squared total spin (S-z)(2) with respect to the longitudinal components, the dimerization parameter, and the correlation functions between the nearest neighbors with respect to longitudinal and transverse spin components. On the basis of the Monte Carlo calculations, the critical temperatures and possible energy gaps at the band center are determined for the antiferromagnets CuWO4 and Bi2CuO4 and for the singlet compounds (VO)(2)P2O7 and CuGeO3 , agreeing satisfactorily with existing results, and new effects are also predicted. (C) 2000 MAIK "Nauka / Interperiodica".
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Two-particle spin-singlet excitations in coupled spin-1/2 antiferromagnetic alternating chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2001. - Vol. 13, Is. 14. - P.3403-3410. - ISSN 0953-8984, DOI 10.1088/0953-8984/13/14/313
Примечания : Cited References: 14
Предметные рубрики: MAGNETIC-PROPERTIES
LIGHT-SCATTERING
CUGEO3
S=1/2
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--chemical bonds--electron transport properties--monte carlo methods--particles (particulate matter)--quantum theory--thermal effects--antiferromagnetic alternating chains--excitation spectrum--interchain exchange--mean-field approximation--quantum monte carlo method--singlet gaps--spin-singlet excitations--energy gap
Аннотация: The spectrum of the two-particle spin-singlet (DeltaS(z) = 0, +/-1) excitations of a weakly coupled antiferromagnetic spin-1/2 alternating (J(1) +/- delta) chain is calculated using a mean-field approximation for the interchain exchange (J(2)) by the quantum Monte Carlo method. The bandwidth change of these excitations, the mass gaps in the singlet-singlet excitation spectrum, the top boundaries of the bands and the velocities of these excitations are estimated as functions of the alternating bond delta. The temperatures at which the singlet gaps close are determined.
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14.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Parshin A. S., Kushenkov S. A., Aleksandrova G. A., Dolbak A. E., Pchelyakov O. P., Olshanetsky B. Z., Ovchinnikov S. G.
Заглавие : Application of inelastic electron scattering cross sections for quantitative analysis
Коллективы : "Trends in Nanomechanics and Nanoengineering", workshop, Сибирский федеральный университет, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : Workshop "Trends in Nanomechanics and Nanoengineering": book of abstracts/ предс. сем. K. S. Aleksandrov ; зам. предс. сем.: G. S. Patrin, S. G. Ovchinnikov ; чл. лок. ком.: N. N. Kosyrev, A. S. Fedorov [et al]. - 2009. - P.20
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M., Rumyantsev V. G.
Заглавие : Manifestations of the higher moments of the orientation distribution function of molecules in the spectral properties of an impurity nematic
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 98, Is. 6. - P1146-1151. - ISSN 1063-7761, DOI 10.1134/1.1777627
Примечания : Cited References: 15
Предметные рубрики: LIQUID-CRYSTAL
SCATTERING
PHASES
MATRIX
ORDER
DYES
Ключевые слова (''Своб.индексиров.''): absorption--band structure--impurities--molecular dynamics--polarization--spectrum analysis--distribution function--local field parameters--splitting--temperature dependence--nematic liquid crystals
Аннотация: The polarized electronic absorption spectra, orientation ordering, and the special local field features were studied for push-pull linear dye molecules with strong donor-acceptor electronic conjugation of terminal fragments in the matrix of a nematic liquid crystal. The temperature-induced inversion of the sign of the splitting of polarized impurity absorption bands was observed. This effect was shown to be caused by the statistical character of orientation ordering of impurity molecules and manifestation of the higher moments of the orientation distribution function. The dependence of local field parameters (Lorentz tensor components) of impurity molecules on their orientation ordering was established. This dependence was used to reproduce the temperature dependence of the orientation order parameter of the matrix. (C) 2004 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : Effects of strong electron correlations in X-ray and electron spectra of high-T-c superconductors
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 5. - P788-809. - ISSN 1063-7834, DOI 10.1134/1.1131293
Примечания : Cited References: 92
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
COPPER-OXIDE SUPERCONDUCTORS
MULTIPLE-SCATTERING ANALYSIS
HIGH-ENERGY SPECTROSCOPY
ABSORPTION-SPECTRA
PHOTOELECTRON-SPECTRA
EDGE STRUCTURE
PHOTOEMISSION SPECTRA
INCOMPLETE SHELL
SINGLE-CRYSTAL
Аннотация: The current state of theoretical and experimental studies on the electronic structure of high-T-c superconductors is analyzed. The agreement between the theory and experimental spectroscopic data is shown to be rather poor in certain cases. The reason is that the X-ray and electronic spectra reveal strong electron correlations. At the same time, no realistic model has been developed up to now in which both one-electron and multielectron mechanisms of the formation of the spectra could be described in a unified way in compounds containing transition and rare-earth elements. In this paper, particular attention is paid to a sudden-perturbation model, by which it has been possible to describe or interpret some X-ray and electronic spectra, including both one-electron and multielectron effects. (C) 2000 MAIK "Nauka/Interperiodica".
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Yakobson B. I., Scuseria G. E.
Заглавие : Mechanisms of inelastic scattering of low-energy protons by C6H6, C-60, C6F12, and C60F48 molecules
Разночтения заглавия :авие SCOPUS: Mechanisms of inelastic scattering of low-energy protons by C 6H6, C60, C6F12, and C60F48 molecules
Место публикации : Phys. Solid State: SPRINGER, 2006. - Vol. 48, Is. 1. - P177-184. - ISSN 1063-7834, DOI 10.1134/S106378340601032X
Примечания : Cited References: 23
Предметные рубрики: DYNAMICS SIMULATIONS
FULLERENES
COMPLEXES
BUCKMINSTERFULLERENE
HELIUM
ATOMS
Аннотация: The mechanisms of inelastic scattering of low-energy protons with a kinetic energy of 2-7 eV by C6H6, C6F12, C-60, and C60F48 molecules are studied using the methods of quantum chemistry and nonempirical molecular dynamics. It is shown that, for the C6H6 + proton and C-60 + proton systems, starting from a distance of 6 angstrom from the carbon skeleton, the electronic charge transfer from the aromatic molecule to H+ occurs with a probability close to unity and transforms the H+ ion into a hydrogen atom and the neutral C6H6 and C-60 molecules into cation radicals. The mechanism of interaction of low-energy protons with C6F12 and C60F48 molecules has a substantially different character and can be considered qualitatively as the interaction between a neutral molecule and a point charge. The Coulomb perturbation of the system arising from the interaction of the noncompensated proton charge with the Mulliken charges of fluorine atoms results in an inversion of the energies of the electronic states localized, on the one hand, on the positively charged hydrogen ion and, on the other hand, on the C6F12 and C60F48 molecules. As a result, the neutral molecule + proton state becomes the ground state. In turn, this inversion makes the electronic charge transfer energetically unfavorable. Quantum-chemical and molecular-dynamics calculations on different levels of theory showed that, for fluorine derivatives of some aromatic structures (C6F12, C60F48), the barriers to proton penetration through carbon hexagons are two to four times lower than for the corresponding parent systems (C6H6, C-60). This effect is explained by the absence of active pi-electrons in the case of fluorinated molecules.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Ovchinnikov S. G.
Заглавие : The strong electron correlation effects in XAFS spectra of HTSC cuprates
Место публикации : J. Phys. IV. - 1997. - Vol. 7: 9th International Conference on X-Ray Absorption Fine Structure (AUG 26-30, 1996, GRENOBLE, FRANCE), Is. C2. - P.183-185. - ISSN 1155-4339
Примечания : Cited References: 11
Предметные рубрики: X-RAY-ABSORPTION
MULTIPLE-SCATTERING ANALYSIS
EDGE STRUCTURE
LA2CUO4
XANES
Аннотация: Theoretical XAFS spectra of highly correlated copper oxides have been presented as a product of a single-electron part obtained by the SCF X alpha- SW method, and a multi-electron part obtained by the multi-band multi-electron p-d model. The main line of CuK-spectrum of La2CuO4 was aligned to the Cud(10) (L) under bar configuration and the single satellite line was aligned to the Cud(9). Comparison of the theoretical data with the experimental ones shows that the ground state of the two-holes in the CuO4 doped cell is triplet. The last conclusion has been confirmed by analysis of CuL2,3-spectra of two-hole impurity states of doped CuO4 cell. Another interesting future of CuL2,3-spectra a peak 2.8 eV higher the threshold was aligned to the transitions into quasi-stationary states due to existence of a high barrier in the Cud-state potential.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Tyurnev V. V.
Заглавие : Resonances of electromagnetic oscillations in a spherical metal nanoparticle
Место публикации : Microw. Opt. Technol. Lett.: Wiley-Blackwell, 2016. - Vol. 58, Is. 8. - P.1883-1886. - ISSN 0895-2477, DOI 10.1002/mop.29930. - ISSN 1098-2760(eISSN)
Примечания : Cited References:18
Предметные рубрики: OPTICAL-PROPERTIES
LIGHT
Ключевые слова (''Своб.индексиров.''): plasmonics--scattering--particles--resonators--resonant modes
Аннотация: Electrodynamic analysis of plasma oscillations in a spherical metal nanoparticle is performed. It is shown that typical reduction in the frequency and quality factor of the resonances with increasing nanoparticle radius fades if the mode number grows. Depending on the particle radius, the resonant enhancement of the electric field might considerably either increase or decrease with increasing mode number. (C) 2016 Wiley Periodicals, Inc.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Tyurnev V. V.
Заглавие : Scattering of electromagnetic waves by a metal lattice placed at the interface of two media
Место публикации : J. Commun. Technol. Electron.: Maik Nauka-Interperiodica Publishing, 2017. - Vol. 62, Is. 7. - P.750-758. - ISSN 10642269 (ISSN), DOI 10.1134/S1064226917070026
Примечания : Cited References: 24
Ключевые слова (''Своб.индексиров.''): bandpass filters--electromagnetic waves--frequency bands--frequency response--optical multilayers--reflection--dielectric layer--efficient control--electromagnetic analysis--lattice periods--metal lattices--optical bandpass filters--scattering matrices--scattering of electromagnetic waves--electromagnetic wave scattering
Аннотация: Simple formulas for determination of components of the scattering matrix of a plane electromagnetic wave incident along the normal onto a thin infinite 2D metal lattice with square windows placed at the interface of two media are derived for the first time. Frequency responses (FRs) of this structure calculated with the use of these formulas agree well with responses obtained by the numerical electromagnetic analysis of a 3D model in the case when the lattice period is less than one-half of the wavelength. The capability of efficient control of the FR of the analyzed structure by means of variation in the width of conductors and the lattice period enables application of this lattice for fabrication of a reflector with prescribed reflectivity. Such reflectors at interfaces of dielectric layers are required, for example, in the design of multilayer sufaces radio transparent in a specified frequency band or optical bandpass filters.
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