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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Prokert F., Aleksandrov K. S.
Заглавие : Neutron scattering studies on phase transition and phonon dispersion in Cs//2NaBiCl//6
Место публикации : Phys Status Solidi B. - 1984. - Vol. 124, Is. 2. - P.503-513. - ISSN 0370-1972, DOI 10.1002/pssb.2221240208
Примечания : Cited References: 24
Ключевые слова (''Своб.индексиров.''): neutrons - scattering--phonons--phase transition--phonon dispersion--cesium compounds
Аннотация: The structural phase transition (PT) of elpasolite-type crystal Cs//2NaBiCl//6 is investigated by neutron scattering. At first the acoustic phonon dispersion is measured at room temperature for the high-symmetric directions DELTA , SIGMA , and LAMBDA of the Brillouin zone. The transverse rotary mode is studied for phonon wave vectors q parallel as well as perpendicular to DELTA and the dispersion shows a quasi-two-dimensional behavior of the Cl-octahedra rotation. At cooling down to the PT, this branch shows a softening along DELTA , reaching the lowest energies at the zone center. The PT, which is found to be of weakly first order, seems to be driven and triggered by the ferrorotative octahedra mode.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Podoprigora V. G., Remizov I. A., Shabanov V. F., Botvich A. N.
Заглавие : Surface phonons in molecular-crystals
Место публикации : Phys. Status Solidi B. - 1987. - Vol. 139, Is. 1. - P.109-115. - ISSN 0370-1972, DOI 10.1002/pssb.2221390108
Примечания : Cited References: 9
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolbysheva O. P., Sadreev A. F.
Заглавие : The coupling of solitons via phonons in the phi-4-phi-2-model
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 100, Is. 4. - P.1262-1271. - ISSN 0044-4510
Примечания : Cited References: 9
Аннотация: The indirect coupling of solitons via phonons in the one-dimensional model phi-4-phi-2, as well as the coupling of plane domain walls in the d-dimensional model are analyzed. Both analytically and numerically, the indirect coupling is shown to be repulsive and significantly more long-range than the static coupling of solitons. The soliton coupling involving the soliton pinning is considered as well.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Vtyurin A. N., Bulou A., Voronov V. N.
Заглавие : Raman spectra and phase transitions in the Rb2KScF6 elpasolite
Коллективы : Russian-CIS-Baltic-Japanese symposium on ferroelectricity
Место публикации : Ferroelectrics: Taylor & Francis LTD, 2003. - Vol. 284. - P221-238. - ISSN 0015-0193, DOI 10.1080/00150190390204709
Примечания : Cited References: 13
Предметные рубрики: LIGHT-SCATTERING
OPTICAL PHONONS
MODE
Ключевые слова (''Своб.индексиров.''): rb2kscf6--phase transitions--raman scattering--soft modes
Аннотация: Raman spectra of Rb2KScF6 elpasolite crystal have been studied in a wide temperature range, including two transition points: from cubic to tetragonal, and then-to the monoclinic phase. For the first time both for this crystal and for fluoride elpasolites in general soft modes restoration has been found below transition points; in agreement with selection rules a splitting of degenerate modes has been observed as well both for lattice vibrations and internal modes of ScF6 octahedrons. Parameters of Raman lines have been quantitatively analyzed and found in good agreement with known thermodynamic characteristics of these transitions; in particular, lines widths are shown to be determined by tree-phonons anharmonic interactions. A wide region of pretransitional fluctuations was found above the upper transition point.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Flerov I. N., Bondarev V. S., Sciau P.
Заглавие : Heat capacity study of relaxor PbMg1/3Nb2/3O3 in a wide temperature range
Разночтения заглавия :авие SCOPUS: Heat capacity study of relaxor PbMg1/3Nb2/3O 3 in a wide temperature range
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2003. - Vol. 96, Is. 3. - P531-537. - ISSN 1063-7761, DOI 10.1134/1.1567427
Примечания : Cited References: 21
Предметные рубрики: DIFFUSE PHASE-TRANSITION
FERROELECTRICS
Ключевые слова (''Своб.индексиров.''): differential scanning calorimetry--mathematical models--phonons--random processes--specific heat--spectrum analysis--thermal effects--bond-random field models--wide temperature intervals--lead compounds
Аннотация: Heat capacity of the PbMg1/3Nb2/3O3 compound is measured using the methods of adiabatic and differential scanning calorimetry in the temperature range 80-750 K. Two blurred anomalies on the C-p(T) dependence are observed in wide temperature intervals of 200- 400 K and 500-700 K. The results of studies are discussed together with data on the structure and phonon spectrum in the framework of spherical random bond-random field model. (C) 2003 MAIK "Nauka/Interperiodica".
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Nonadiabatic interaction of acoustic phonons with spins S=1/2 in the two-dimensional Heisenberg model
Разночтения заглавия :авие SCOPUS: Nonadiabatic interaction of acoustic phonons with spins S = 1/2 in the two-dimensional heisenberg model
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 5. - P969-977. - ISSN 1063-7761, DOI 10.1134/1.1633952
Примечания : Cited References: 18
Предметные рубрики: QUANTUM MONTE-CARLO
EU2CUO4
GD2CUO4
POLARON
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--correlation methods--crystal symmetry--magnetic couplings--magnetic moments--magnetization--monte carlo methods--quantum theory--acoustic phonons--nonadiabatic interaction--orthorhombicity--quantum spin liquid transitions--phonons
Аннотация: The ground state of a two-dimensional antiferromagnet having spins S = 1/2 and interacting with acoustic phonons is investigated in the nonadiabatic approximation using the quantum-mechanical Monte Carlo method. The critical parameters of the spin-phonon coupling, corresponding to the formation of bound spin-phonon excitations, crystal symmetry lowering, and the emergence of a gap in the spin excitation spectrum, as well as the antiferromagnet-quantum spin liquid transition, are determined. The orthorhombicity parameter, the sublattice magnetization, the violation of the spherical symmetry of spin-spin correlation functions, and the magnetic moment in Gd2CuO4 and Eu2CuO4 are calculated. (C) 2003 MAIK "Nauka / Interperiodica".
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zinenko V. I., Sofronova S. N.
Заглавие : The nonempirical calculation of the cation ordering and lattice dynamics in the solid solutions of PbSc1/2Nb1/2O3 and PbSc1/2Ta1/2O3
Место публикации : 11th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 25-30, 2004, St Petersburg, RUSSIA): WILEY-V C H VERLAG GMBH, 2004. - P3047-3051. - ISBN 3-527-40588-7, DOI 10.1002/pssc.200405286
Примечания : Cited References: 10
Аннотация: An effective Hamiltonian for the study of Sc-Nb(Ta) cation ordering in PbSc1/2Nb(Ta)(1/2)O-3 solid solutions is written out. To determine the parameters of the effective Hamiltonian, a nonempirical calculation is performed within an ionic-crystal model taking into account the deformation, dipole and quadrupole polarizabilities of ions. The phase transition temperatures are calculated by mean field, cluster approximations and Monte-Carlo method. Within the same ionic-crystal model, we calculated the high-frequency permittivity, Born dynamic charges, and the phonon spectrum for a completely disordered and ordered phases. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylova S. N., Vtyurin A. N., Bulou A., Krylov A. S., Zamkova N. G.
Заглавие : Lattice dynamics and raman scattering spectrum of elpasolite Rb2KScF6: Comparative analysis
Разночтения заглавия :авие SCOPUS: Lattice dynamics and Raman scattering spectrum of elpasolite Rb 2KScF6: Comparative analysis
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 7. - P1311-1319. - ISSN 1063-7834, DOI 10.1134/1.1778457
Примечания : Cited References: 18
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
LIGHT-SCATTERING
OPTICAL PHONONS
SOFT-MODE
CRYSTAL
Аннотация: Raman scattering spectra of elpasolite Rb2KScF6 are studied in a wide temperature range including two phase transitions: from the cubic to the tetragonal phase and then to the monoclinic phase. The experimental Raman scattering spectrum is compared with the lattice vibration spectra of these phases calculated using an ab initio approach. A number of anomalies (caused by structural rearrangement during the phase transitions) are revealed and quantitatively analyzed in the ranges of both the intramolecular vibrations of the octahedron molecular ScF6 ions and low-frequency intermolecular lattice vibrations. The interaction between low-frequency intramolecular vibrations and the intermolecular modes is found to be significant, and strong resonance interaction of the rotational soft modes (which are recovered below the phase transition points) with hard low-frequency vibrations of the rubidium ion sublattice is detected. These interactions are shown to substantially complicate the spectra. (C) 2004 MAIK "Nauka / Interperiodica".
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Two-dimensional quantum spin liquid with S=1/2 spins interacting with acoustic phonons
Разночтения заглавия :авие SCOPUS: Two-dimensional quantum spin liquid with S = 1/2 spins interacting with acoustic phonons
Место публикации : Phys. Lett. A. - 2004. - Vol. 333, Is. 5-6. - P.446-449. - ISSN 0375-9601, DOI 10.1016/j.physleta.2004.10.064
Примечания : Cited References: 11
Предметные рубрики: ANTIFERROMAGNET
Ключевые слова (''Своб.индексиров.''): spin-phonon interactions--spin-liquid--spinon excitations--spin-liquid--spin-phonon interactions--spinon excitations--ferromagnetic material--acceleration--acoustics--article--density--energy--liquid--magnetic field--mathematical analysis--monte carlo method--phonon--quantum mechanics
Аннотация: The spin density of states of a two-dimensional antiferromagnet in magnetic field having spins-1/2 and interacting with acoustic phonons is investigated in the nonadiabatic approximation using the quantum Monte Carlo method. It is found the gap energy A in the single particle spin excitations spectrum closes at magnetic field Delta similar or equal to H-c, W-ph W-s and Delta similar or equal to (1/2)H-c, W-ph W-s, where W-ph and W-s are the bandwidths of phonon and spin excitations in antiferromagnet. (C) 2004 Elsevier B.V All rights reserved.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Vtyurin A. N., Goryainov S. V., Krylov A. S., Krylova S. N., Shefer A. D., Zamkova N. G., Zinenko V. I.
Заглавие : Raman spectra and pressure-induced lattice instabilities in RbMnCl3 crystal
Разночтения заглавия :авие SCOPUS: Raman spectra and pressure-induced lattice instabilities in RbMnCl 3 crystal
Место публикации : 11th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 25-30, 2004, St Petersburg, RUSSIA): WILEY-V C H VERLAG GMBH, 2004. - 11th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 25-30, 2004, St Petersburg, RUSSIA). - P3097-3100. - ISBN 3-527-40588-7, DOI 10.1002/pssc.200405332
Примечания : Cited References: 14
Предметные рубрики: PHASE-TRANSITION
SPECTROSCOPY
Ключевые слова (''Своб.индексиров.''): frequencies--hydrostatic pressure--mathematical models--parameter estimation--raman scattering--spectrometers--stability--ambient conditions--anomalies--lattice instabilities--structural units--rubidium compounds
Аннотация: Raman scattering spectra of the RbMnCl3 crystal have been studied under ambient conditions and under high hydrostatic pressure. The results produced have been interpreted with the ab initio model. The experimental data agree well with the estimated values in the low frequency range and show a slightly worse agreement at higher frequencies. A phase transition from the hexagonal phase to the perovskite phase predicted earlier within the same model was observed under high pressure (above 0.7 GPa) and new transitions to lower symmetry phases were found at higher pressures (1.1 GPa and 5 GPa). (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Spinon excitations in 2D uantum spin liquid with S=1/2 interacted with acoustic phonons
Коллективы : Российская академия наук, Научный совет по физике конденсированных сред РАН, Научный совет РАН по физике низких температур, Сибирское отделение РАН, Красноярский научный центр Сибирского отделения РАН, Институт физики им. Л.В. Киренского Сибирского отделения РАН, Красноярский государственный университет, Красноярский государственный технический университет, Институт физики металлов Уральского отделения РАН, Euro-asian symposium "Trends in magnetism", "Trends in magnetism", Euro-Asian Symposium
Место публикации : EASTMAG-2004: abstract book/ org. com. K. S. Aleksandrov [et al.]. - Krasnoyarsk, 2004. - Sect.: Fundamental magnetic properties. - P.54
Примечания : Cited References: 3
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Vtyurin A. N., Isaenko L. I., Krylova S. N., Yelisseyev A., Shebanin A. P., Turchin P. P., Zamkova N. G., Zinenko V. I.
Заглавие : Raman spectra and elastic properties of KPb2Cl5 crystals
Место публикации : 11th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 25-30, 2004, St Petersburg, RUSSIA): WILEY-V C H VERLAG GMBH, 2004. - P3142-3145. - ISBN 3-527-40588-7, DOI 10.1002/pssc.200405401
Примечания : Cited References: 10
Предметные рубрики: LATTICE-DYNAMICS
Ключевые слова (''Своб.индексиров.''): computer simulation--crystal structure--eigenvalues and eigenfunctions--halogen compounds--nonlinear optics--phonons--potassium compounds--vectors--elastic constants--heavy cations--ionic electron envelopes--ionic interactions--raman scattering
Аннотация: Raman scattering spectra and elastic constants of KPb2Cl5 crystals have been studied. The results obtained are interpreted in terms of the ab initio lattice dynamics model taking into account multipole moments of ionic electron envelopes. The experimental results have been found to be in good agreement with numerical simulation; the narrow phonon spectra are shown to be due to a considerable contribution of heavy cations into the eigenvectors of the higher frequency lattice modes.
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13.

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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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fausti D., Nugroho A. A., van Loosdrecht PHM, Klimin S. A., Popova M. N., Bezmaternykh L. N.
Заглавие : Raman scattering from phonons and magnons in RFe3(BO3)(4)
Разночтения заглавия :авие SCOPUS: Raman scattering from phonons and magnons in RFe3 (BO3) 4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2006. - Vol. 74, Is. 2. - Ст.24403. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.024403
Примечания : Cited References: 26
Предметные рубрики: IRON BORATE GDFE3(BO3)(4)
LIGHT-SCATTERING
CRYSTALS
ND
CRYSTALLIZATION
TRANSITIONS
GENERATION
LASER
Аннотация: Inelastic light scattering spectra of several members of the RFe3(BO3)(4) family reveal a cascade of phase transitions as a function of temperature, starting with a structural, weakly first-order, phase transition followed by two magnetic phase transitions. Those consist of the ordering of the Fe-spin sublattice, revealed by all the compounds, and a subsequent spin-reorientational transition for GdFe3(BO3)(4). The Raman data evidence a strong coupling between the lattice and magnetic degrees of freedom in these borates. The Fe-sublattice ordering leads to a strong suppression of the low-energy magnetic scattering, and a multiple peaked two-magnon scattering continuum is observed. Evidence for short-range correlations is found in the "paramagnetic" phase by the observation of a broad magnetic continuum in the Raman data, which persists up to surprisingly high temperatures.
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zamkova N. G., Zinenko V. I.
Заглавие : Lattice dynamics and ferroelectric phase transitions in solid solutions PbSc(1/2)Nb(1/2)O(3) and PbSc(1/2)Ta(1/2)O(3)
Разночтения заглавия :авие SCOPUS: Lattice dynamics and ferroelectric phase transitions in solid solutions PbSc1/2Nb1/2O3 and PbSc1/2Ta 1/2O3
Место публикации : 12TH INTERNATIONAL CONFERENCE ON PHONON SCATTERING IN CONDENSED MATTER (PHONONS 2007). Ser. Journal of Physics Conference Series: IOP PUBLISHING LTD, 2007. - Vol. 92: 12th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 15-20, 2007, Paris, FRANCE). - Ст.12162. - ISBN 1742-6588, DOI 10.1088/1742-6596/92/1/012162
Примечания : Cited References: 14
Предметные рубрики: PEROVSKITES
BATIO3
Аннотация: The calculation of the lattice dynamics and ferroelectric phase transitions for disordered and ordered solid solution PbSc(1/2)Nb(1/2)O(3) and PbSC(1/2)Ta(1/2)O(3) in the framework of the Gordon-Kim model are performed. The unstable ferroelectric modes were found in all cases. The model Hamiltonian for the study finite temperature behavior during for the ferroelectric phase transition is used. The transition temperatures, phase sequences and spontaneous polarizations are calculated by Monte-Carlo method.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Maksimov E. G., Sofronova S. N.
Заглавие : Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb1/2O3 solid solutions
Разночтения заглавия :авие SCOPUS: Lattice dynamics and ferroelectric instability in ordered and disordered PbSc1/2Ta1/2O3 and PbSc1/2Nb 1/2O3 solid solutions
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 105, Is. 3. - P617-625. - ISSN 1063-7761, DOI 10.1134/S1063776107090191
Примечания : Cited References: 23
Предметные рубрики: RELAXOR FERROELECTRICS
PHASE-TRANSITION
LOCAL-STRUCTURE
PB(SC1/2NB1/2)O-3
PEROVSKITE
CRYSTALS
Ключевые слова (''Своб.индексиров.''): dipole moment--lattice vibrations--negative ions--phonons--positive ions--solid solutions--dynamic born charges--ferroelectric instabilities--frequency spectra--gordon-kim models--oxygen anions--phonon spectra--ferroelectricity
Аннотация: The dynamic Born charges and the frequency spectra of lattice oscillations in the crystals of ordered and disordered PbSc1/2Ta1/2O3 (PST) and PbSc1/2Nb1/2O3 (PSN) solid solutions have been calculated within the framework of the generalized Gordon-Kim model with allowance for the dipole and quadrupole polarizabilities. The phonon spectra of both compounds contain ferroelectric soft modes. The influence of various interactions on the magnitude of dynamic charges and ferroelectric instability in PSN and PST solid solutions has been studied and it is shown that both these charges and the ferroelectric instability are determined by the competition between long-range dipole-dipole interactions and short-range dipole-charge interactions, the determining role played by the interaction of Nb (Ta) cations and oxygen anions in the Nb-O (Ta-O) bond direction.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Pavlovskii M. S.
Заглавие : Lattice dynamics and the phase transition from the cubic phase to the tetragonal phase in the LaMnO3 crystal within the polarizable-ion model
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 9. - P1749-1758. - ISSN 1063-7834, DOI 10.1134/S1063783407090235
Примечания : Cited References: 23
Предметные рубрики: NEUTRON-DIFFRACTION
PEROVSKITES
MANGANITES
PHONONS
Аннотация: The paper reports on the results of ab initio calculations of the static and dynamic properties of the LaMnO3 crystal with a perovskite structure in the cubic, rhombohedral, and orthorhombic phases. The calculations are performed within the ionic crystal model, which takes into account the deformability and polarizability of the ions. It is revealed that the spectrum of lattice vibrations in the cubic phase contains unstable vibrational modes, which occupy the phase space in the entire Brillouin zone. The eigenvectors of the softest mode at the boundary point R of the Brillouin zone are associated with the displacements of the oxygen ions and correspond to the "rotation" of the MnO6 octahedron. The condensation of one, two, and three components of this mode leads to the tetragonal, orthorhombic, and rhombohedral distortions of the structure. The structural phase transition is described in terms of the local mode approximation with the use of the double perovskite unit cell, in which the MnO6 octahedron is explicitly separated. The parameters of the model Hamiltonian are determined. The static properties are investigated by the Monte Carlo method. The calculated temperature of the phase transition from the cubic phase (9800 K) is considerably higher than the melting temperature of the crystal under investigation. The calculated frequencies of long-wavelength lattice vibrations in the experimentally observed orthorhombic and rhombohedral phases are in reasonable agreement with experimental data.
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18.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Vtyurin A. N., Krylov A. S., Gerasimova J. V., Fokina V. D., Kocharova A. G., Laptash N. M., Voyt E. I., Surovtsev N. V.
Заглавие : Raman scattering study of ordering processes and phase transitions in A(2)BWO(3)F(3) oxyfluorides crystals
Разночтения заглавия :авие SCOPUS: Raman scattering study of ordering processes and phase transitions in A2BWO3F3oxyfluorides crystals
Место публикации : 12TH INTERNATIONAL CONFERENCE ON PHONON SCATTERING IN CONDENSED MATTER (PHONONS 2007). Ser. Journal of Physics Conference Series: IOP PUBLISHING LTD, 2007. - Vol. 92: 12th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004) (JUL 15-20, 2007, Paris, FRANCE). - Ст.12158. - ISBN 1742-6588, DOI 10.1088/1742-6596/92/1/012158
Примечания : Cited References: 6
Предметные рубрики: (NH4)(3)WO3F3
Аннотация: Raman spectra of perovskite-like (NH(4))(3)WO(3)F(3), (NH(4))(2)KWO(3)F(3) and Cs(2)(NH(4))WO(3)F(3) oxyfluorides are obtained in a wide temperature range including transition points. Transition anomalies are found and analyzed. Transformation in (NH(4))(3)WO(3)F(3) is shown to be bound with octahedron groups ordering and strong distortion of ammonium ions due to H-bond formation, that is accompanied by cell volume multiplication, hardening and formation of complex discrete low frequency lattice spectrum. Same cell doubling was found in (NH(4))(2)KWO(3)F(3), but without lattice ordering Cs(2)(NH(4))WO(3)F(3) lattice stays disordered down to 15 K.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Davydov V. Yu., Klochikhin A. A., Smirnov A. N., Strashkova I. Y., Krylov A. S., Lu H., Schaff W. J., Lee H. M., Hong Y. L., Gwo S.
Заглавие : Selective excitation of E-1(LO) and A(1)(LO) phonons with large wave vectors in the Raman spectra of hexagonal InN
Коллективы : RFBR [09-02-01280]; NSC-RFBR [08-02-92003-HHC]
Разночтения заглавия :авие SCOPUS: Selective excitation of E1 (LO) and A1 (LO) phonons with large wave vectors in the Raman spectra of hexagonal InN
Место публикации : Phys. Rev. B. - 2009. - Vol. 80, Is. 8. - Ст.81204. - ISSN 1098-0121, DOI 10.1103/PhysRevB.80.081204
Примечания : Cited References: 15. - We are thankful to B. N. Mavrin and A. N. Vtyurin for the arrangement NIR measurements and S. A. Permogorov for the critical reading of the manuscript. This work was supported by RFBR (Grant No. 09-02-01280), NSC-RFBR (Grant No. 08-02-92003-HHC), and the Program of RAS "New materials and structures."
Предметные рубрики: SCATTERING
RESONANCE
Ключевые слова (''Своб.индексиров.''): iii-v semiconductors--indium compounds--phonon dispersion relations--raman spectra--wide band gap semiconductors
Аннотация: It is shown that dispersions of E-1(LO) and A(1)(LO) modes of InN can be restored in a wide interval of wave vectors by studying impurity-induced first-order Raman scattering as a function of exciting light energy. It is also shown that due to the resonance character of scattering the observed phonon energies correspond to the wave vectors strictly defined by exciting photon energies. The frequencies of E-1(LO) and A(1)(LO) phonons at the Gamma point obtained by extrapolation to zero wave vectors were found to be 604 and 592 cm(-1), respectively.
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20.

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