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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V., Zlotnikov A. O., Shustin M. S.
Заглавие : Strong Coulomb interactions in the problem of Majorana modes in a wire of the nontrivial topological class BDI
Коллективы : RAS Presidium programs for fundamental research [32, 12]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-32-00443, 19-02-00348]; Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [19-42-240011]; Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific SchoolsLeading Scientific Schools Program [MK-1641.2020.2, MK-3594.2018.2]; Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" [18-46-007]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 12. - Ст.125431. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.125431. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 60. - We acknowledge fruitful discussions with V. V. Valkov and V. A. Mitskan. The reported study was funded by the RAS Presidium programs for fundamental research Nos. 12 and 32, Russian Foundation for Basic Research (Projects No. 18-32-00443 and No. 19-02-00348), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: "Coulomb interactions in the problem of Majorana modes in low-dimensional systems with nontrivial topology" (Grant No. 19-42-240011). S.V.A. and A.O.Z. are grateful to the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools, Projects No. MK-1641.2020.2 and No. MK-3594.2018.2. S.V.A. acknowledges the support from the Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" (Grant No. 18-46-007).
Предметные рубрики: QUANTUM
POLARIZATION
TRANSITION
FERMIONS
SPECTRUM
STATE
Аннотация: In this study, the problem of strong Coulomb interactions in topological superconducting wire is analyzed by means of the density-matrix-renormalization-group (DMRG) approach. To analyze properties of edge states in the BDI-class structure, a quantity called Majorana polarization is used. From its dependence on wire length and an entanglement-spectrum degeneracy, topological phase diagrams are obtained. The DMRG calculations for the Shubin-Vonsovsky-type model of the wire show the transformation of phases with Majorana single and double modes (MSMs and MDMs, respectively) under the increase of onsite and intersite correlations. In particular, we demonstrate different scenarios including the possibilities of both induction and suppression of the MSMs and MDMs. It is shown that in the strongly correlated regime, the contributions of single-particle excitations to the Majorana-type states significantly decrease at low magnetic fxields. Moreover, the t-J*-V model is derived allowing to study the effective interactions and improve the DMRG numerics. It is found out that in the limiting case of the effective Hamiltonian with infinitely strong onsite repulsion, t model, the topological phases are destroyed. Finally, the ways to probe the MSMs and MDMs via the features of caloric functions are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova M. N., Stanislavchuk T. N., Malkin B. Z., Bezmaternykh L. N.
Заглавие : Breaking of the Selection Rules for Optical Transitions in the Dielectric PrFe3(BO3)(4) Crystal by a Praseodymium-Iron Exchange Interaction
Коллективы : RFBR [07-02-01185, 07-02-00704]; Russian Academy of Sciences
Разночтения заглавия :авие SCOPUS: Breaking of the selection rules for optical transitions in the dielectric PrFe3(BO3)4 crystal by a praseodymium-iron exchange interaction
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2009. - Vol. 102, Is. 18. - Ст.187403. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.102.187403
Примечания : Cited References: 26. - This work was supported in part by the RFBR under Grants No. 07-02-01185 and No. 07-02-00704 and by the Russian Academy of Sciences under the Programs for Basic Research.
Предметные рубрики: SINGLE-CRYSTAL
GDFE3(BO3)(4)
PHASE
DYFE3(BO3)(4)
SPECTRUM
LINES
Ключевые слова (''Своб.индексиров.''): magnetic ordering temperatures--optical spectrum--order parameters--point symmetries--selection rules--exchange interactions--neon--praseodymium--single crystals--crystal symmetry
Аннотация: We report on the emergence of new lines in the optical spectrum of the PrFe3(BO3)(4) single crystal at the magnetic ordering temperature. The transitions between singlet crystal-field sublevels of Pr3+ ion with the same transformational properties, strictly forbidden for the trigonal D-3 point symmetry of this ion in PrFe3(BO3)(4), appear below the Neel temperature and grow in intensity as a square of the order parameter. We show that the phenomenon originates from the mixing of wave functions of different Pr3+ sublevels by the Pr-Fe exchange interaction.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pisarev R. V., Kalashnikova A. M., Schops O., Bezmaternykh L. N.
Заглавие : Electronic transitions and genuine crystal-field parameters in copper metaborate CuB2O4
Разночтения заглавия :авие SCOPUS: Electronic transitions and genuine crystal-field parameters in copper metaborate CuB 2O 4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2011. - Vol. 84, Is. 7. - Ст.75160. - ISSN 1098-0121, DOI 10.1103/PhysRevB.84.075160
Примечания : Cited References: 65. - Useful discussions with W. Weber on crystal-field splitting of 3d states in cuprates are appreciated. We thank H.-J. Weber for the help in using Cary 2300 spectrophotometer. This work is supported by the Russian Foundation for Basic Research (project No. 09-02-00070) and Federal Agency for Science and Innovations (Grant No. 02.740.11.0384). A. M. K. acknowledges the financial support from the Committee for Science and Higher Education of the Government of Saint Petersburg.
Предметные рубрики: OPTICAL-ABSORPTION
PHASE-DIAGRAM
CUGEO3
SPECTRUM
SUPERCONDUCTORS
EXCITATIONS
SR2CUO2CL2
SCATTERING
LA2CUO4
CUPRATE
Аннотация: We present and analyze high-resolution alpha-, sigma-, and pi-polarized absorption spectra related to d-d electronic transitions in tetragonal metaborate CuB2O4 where copper Cu2+ ions occupy two crystallographically distinct 4b and 8d positions. The spectra are characterized by exceptionally rich fine structure in the spectral range of 1.4-2.4 eV. Six zero-phonon (ZP) lines originating from the electronic transitions within the Cu2+ ions in both positions are distinguished and identified. Symmetry analysis explains polarization properties of the ZP lines in the 8d positions but only partially explains them in the 4b positions. Reliable assignment of all six ZP lines to specific transitions allowed us to calculate genuine cubic Dq and tetragonal Ds and Dt crystal-field parameters for both positions. We show that the (3r(2) - z(2)) state, the energy of which is the measure of the Jahn-Teller splitting, is the highest 3d state for both types of Cu2+ ion positions. Using the obtained crystal-field parameters as the reference values, we estimated Dq, Ds, and Dt for several other cuprates with different Cu-O bond lengths. In particular, the 3d level splitting in La2CuO4, Nd2CuO4, CuGeO3, Sr2CuO2Cl2, and Cu3B7O13Cl was analyzed. Our estimates suggest that the Jahn-Teller splitting in some of these cuprates is larger than it was assumed previously.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Borisov A. A., Goryachev E. G.
Заглавие : Evolution of the band structure of quasiparticles with doping in copper oxides on the basis of a generalized tight-binding method
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2000. - Vol. 91, Is. 2. - P369-383. - ISSN 1063-7761, DOI 10.1134/1.1311997
Примечания : Cited References: 45
Предметные рубрики: T-J MODEL
CUPRATE SUPERCONDUCTORS
ELECTRONIC-STRUCTURE
EXCITATIONS
DEPENDENCE
TEMPERATURE
DERIVATION
SR2CUO2CL2
SPECTRUM
DENSITY
Аннотация: Two methods for stabilizing the two-hole B-3(1g) state as the ground state instead of the Zhang-Rice singlet are determined on the basis of an orthogonal cellular basis for a realistic multiband pd model of a CuO2 layer and the dispersion relations for the valence band top in undoped and doped cases are calculated. In the undoped case, aside from the valence band, qualitatively corresponding to the experimental ARPES data for Sr2CuO2Cl2 and the results obtained on the basis of the t-t'-J model, the calculations give a zero-dispersion virtual level at the valence band top itself. Because of the zero amplitude of transitions forming the virtual level the response corresponding to it is absent in the spectral density function. In consequence, the experimental ARPES data do not reproduce its presence in this antiferromagnetic undoped dielectric. A calculation of the doped case showed that the virtual level transforms into an impurity-type band and acquires dispersion on account of the nonzero occupation number of the two-hole states and therefore should be detected in ARPES experiments as a high-energy peak in the spectral density. The computed dispersion dependence for the valence band top is identical to the dispersion obtained by the Monte Carlo method, and the ARPES data for optimally doped Bi2Sr2CaCu2O8 + delta samples. The data obtained also make it possible to explain the presence of an energy pseudogap at the symmetric X point of the Brillouin band of HTSC compounds. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Influence of two-particle excited states on the interatomic exchange interaction in La(2)CuO(4)
Разночтения заглавия :авие SCOPUS: Influence of two-particle excited states on the interatomic exchange interaction in La2CuO4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 6. - P1081-1086. - ISSN 1063-7834, DOI 10.1134/S1063783408060140
Примечания : Cited References: 12. - This study was supported by the Integration Project of the Siberian Branch–Ural Branch of the Russian Academy of Sciences (project. no. 74), the Russian Academy of Sciences, the Presidium of the Russian Academy of Sciences within the program “Quantum Macrophysics,” and the Russian Foundation for Basic Research (project nos. 06-02-90537-BNTS and 07-02-00226)
Предметные рубрики: T-J MODEL
COPPER OXIDES
ELECTRON
SPECTRUM
Аннотация: The effective spin Hamiltonian for undoped cuprates is constructed in the framework of the realistic multiband p-d model with the parameters calculated from first principles. The exchange interaction parameter is defined as the sum of the antiferromagnetic and ferromagnetic contributions, which are determined by the two-hole triplet terms. The ferromagnetic and antiferromagnetic contributions of the excited terms compensate each other to a large extent. It is shown that the antiferromagnetic contribution of the two-hole ground singlet (1)A(1g) to the exchange interaction is dominant.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorelik V. S., Pyatyshev, A. Yu., Krylov A. S.
Заглавие : Raman light scattering in sodium nitrite crystals
Коллективы : Russian Foundation for Basic Research [12-02-00491, 13-02-00449, 13-02-90420, 14-02-00190]
Место публикации : Bull. Lebedev Phys. Inst.: Allerton Press, 2016. - Vol. 43, Is. 5. - P.167-173. - ISSN 1068-3356, DOI 10.3103/S1068335616050043. - ISSN 1934-838X(eISSN)
Примечания : Cited References:37. - This study was supported by the Russian Foundation for Basic Research, projects nos. 12-02-00491, 13-02-00449,13-02-90420, 14-02-00190.
Предметные рубрики: NANO2
PHASE
SPECTROSCOPY
PARAPHOTONS
DEPENDENCE
SPECTRUM
SEARCH
Ключевые слова (''Своб.индексиров.''): sodium nitrite--raman scattering--spectrum--polar mode--polariton--ferroelectric--dispersion curves
Аннотация: Raman light scattering spectra of a ferroelectric sodium nitrite crystal is studied in the lattice mode region as the temperature is lowered from room temperature to 123 K. The existence of a Raman satellite corresponding to the soft lattice mode, i.e., transverse polar vibration responsible for the ferroelectric phase transition, is established for the first time. It is found that the intensity of the Raman scattering by the pseudo-scalar low-frequency A (2) mode exceeds the intensity of other lattice variations by an order of magnitude.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorelik V. S., Pyatyshev A. Y., Krylov A. S.
Заглавие : Raman scattering in sodium nitrite crystals near the phase transition
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 1. - P.170-176. - ISSN 10637834 (ISSN), DOI 10.1134/S1063783416010133
Примечания : Cited References: 39. - This study was supported by the Russian Foundation for Basic Research (project nos. 12-02-00491, 13-02-00449, 13-02-90420, and 14-02-00190).
Предметные рубрики: NaNO2
SPECTROSCOPY
DEPENDENCE
SPECTRUM
SEARCH
MODES
Аннотация: Optical Raman spectra of a ferroelectric sodium nitrite crystal have been detected in a wide spectrum range at various temperatures, including the region of the ferroelectric phase transition. A manifestation of a transverse soft polar mode of the A1(z) type responsible for the ferroelectric phase transition has been discovered in the spectrum at room temperature. This mode has been found to become overdamped even far from the ferroelectric phase transition temperature. This mode also appears as a central peak under heating. It has been found that the pseudoscalar mode of the A2 type has the highest intensity in the Raman spectrum of sodium nitrite. The frequency corresponding to the maximum intensity of this mode in the Raman spectrum varies from 130 cm–1 at 123 K to 106 cm–1 at T = 513 K. A fair agreement of the experimental data for the A1(z) mode with the Lyddane–Sachs–Teller relation has been established. The polariton curves for the A1(z) polar mode and the dispersion curves for axinons has been plotted. © 2016, Pleiades Publishing, Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Pichugin K. N., Sadreev A. F., Streda P., Seba P.
Заглавие : Hall-like effect induced by spin-orbit interaction
Место публикации : Phys. Rev. Lett.: AMERICAN PHYSICAL SOC, 1999. - Vol. 83, Is. 2. - P376-379. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.83.376
Примечания : Cited References: 17
Предметные рубрики: BERRYS PHASE
CONDUCTANCE
SCATTERING
SPECTRUM
RINGS
Аннотация: We study the effect of spin-orbit interaction on the electron-transport properties of a cross-junction structure. It results in spin polarization of left and right outgoing electron waves. Consequently, the incoming electron wave of a certain polarization induces a voltage drop perpendicular to the direct current flow between the source and drain of the four-terminal cross structure investigated. The resulting Hall-like resistance is estimated to be of the order of 10(-3)-10(-2)h/e(2) for technologically feasible structures. The effect becomes more pronounced in the vicinity of resonances when the Hall-like resistance changes its sign as a function of the Fermi energy.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Man'kov Yu. I., Tsikalov D. S.
Заглавие : High-frequency susceptibility of a multilayered ferromagnetic system with two-dimensional inhomogeneities
Место публикации : Phys. Solid State. - NEW YORK: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 3. - С. 544-553. - MAR. - ISSN 1063-7834, DOI 10.1134/S1063783410030157
Примечания : Cited Reference Count: 24. - Гранты: This study was supported in part by the Council on Grants from the President of the Russian Federation for the State Support of Scientific Investigations performed by the Leading Scientific Schools (grant no. 3818.2008.3), the Presidium of the Russian Academy of Sciences (Program no. 27.1), and the Ministry of Education and Science within the framework of the Federal Program (State Contract no. 2.740.11.0220).Финансирующая организация: Russian Federation [3818.2008.3]; Presidium of the Russian Academy of Sciences [27.1]; Ministry of Education and Science [2.740.11.0220]
Предметные рубрики: SPIN-WAVE SUSCEPTIBILITY
SPECTRUM
SUPERLATTICES
INTERFACES
Аннотация: This paper reports on the results of the investigation of the high-frequency susceptibility of a layered ferromagnetic structure in which, apart from a periodic change in the magnetic anisotropy parameter from layer to layer, this parameter varies along layers according to a random law (the superlattice with two-dimensional phase inhomogeneities). The evolution of the frequency dependence of the imaginary part of the averaged Green's function in the range of the energy gap (band gap) in the spectrum of waves propagating along the superlattice axis due to the change in the relative root-mean-square fluctuations of the phase gamma 2 has been studied at the boundaries of the odd Brillouin zones. It has been found that, for all odd Brillouin zones, the imaginary part of the Green's function exhibits a universal behavior: the peak corresponding to the edge of the band gap with a lower frequency remains unchanged, and the peak corresponding to the edge of the band gap with a higher frequency is smoothed with an increase in the quantity gamma(2). These effects, which were initially revealed at the boundary of the first Brillouin zone of the sinusoidal superlattice, have been explained, as before, by the specific features of the energy conservation laws for the incident and scattered waves in the lattice with two-dimensional inhomogeneities. It has been demonstrated that an increase in the Brillouin zone number leads to a decrease in the value of gamma(2) at which the peak at the edge of the band gap with a higher frequency disappears.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I.
Заглавие : Effects of cross correlations between 1D and 3D inhomogeneities on the high-frequency susceptibility of superlattices
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 4. - P625-635. - ISSN 1063-7761, DOI 10.1134/S106377610604011X
Примечания : Cited References: 29
Предметные рубрики: ELASTIC MEDIUM THEORY
3-DIMENSIONAL INHOMOGENEITIES
PERIODIC MULTILAYERS
SPIN-WAVES
LOCALIZATION
SPECTRUM
SYSTEMS
MEDIA
DISORDER
Ключевые слова (''Своб.индексиров.''): correlation methods--damping--function evaluation--wave equations--brillouin zone--distribution function--random variables--superlattices
Аннотация: Cross Correlations between components of a mixture of one-dimensional (I D) and three-diniensional (3D) inhomogenetics are described by introducing a distribution function taking into account correlations between absolute values of two random variables in the absence of correlations between the variables themselves. This distribution function is used for derivation and analysis of the superlattice correlation function containing a mixture of cross-correlated 1D and 3D in homogeneitics. The effect of such inhomogeneities on the high-frequency susceptibility at the edge of the first Brillouin zone of the superlattice is investigated. It is shown that positive cross correlations partly suppress the effect of a mixture of 1D and 3D inhomogeneities on the wave spectrum: the gap at the boundary of the Brillouin zone increases, and wave damping decreases as compared to the effect produced by a mixture of 1D and 3D inhomogeneities in the absence of cross correlations. Negative cross correlations lead to the opposite effect: the gap decreases and wave damping increases. Cross correlations also lead to the emergence of new resonance effects: a narrow dip or a narrow peak at the center of the band gap (depending on the sign of the correlation factor).
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I., Tsikalov D. S.
Заглавие : High-Frequency Susceptibility of a Superlattice with 2D Inhomogeneities
Коллективы :
Разночтения заглавия :авие SCOPUS: High-frequency susceptibility of a superlattice with 2D inhomogeneities
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 4. - P603-611. - ISSN 1063-7761, DOI 10.1134/S1063776108100075
Примечания : Cited References: 26. - This work was supported in part by grant no. 3818.2008.3 from the President of Russia in accordance with the program supporting leading scientific schools.
Предметные рубрики: SPIN-WAVE SUSCEPTIBILITY
PERIODIC MULTILAYERS
LOCALIZATION
SYSTEMS
SPECTRUM
DISORDER
MEDIA
Ключевые слова (''Своб.индексиров.''): energy conservation--energy gap--energy management--frequency bands--gallium alloys--green's function--probability density function--three dimensional--band gaps--energy conservation laws--green functions--high frequencies--imaginary parts--magnon crystals--scattered waves--superlattice layers--wave spectrums--phase interfaces
Аннотация: We investigate the high-frequency susceptibility (Green function) of an initially sinusoidal 1D superlattice with 2D phase inhomogeneities that model the deformations of the interfaces between the superlattice layers. For waves propagating along the superlattice axis ( the geometry of a photon or magnon crystal), we have found a peculiar behavior of the imaginary part of the Green function that consists in a significant difference between the peaks corresponding to the edges of the band gap in the wave spectrum. The peak corresponding to the lower-frequency band edge remains essentially unchanged as the root-mean-square fluctuation of the 2D inhomogeneities. 2 increases, while the peak corresponding to the higher-frequency band edge broaden and decreases sharply in height until its complete disappearance with increasing gamma(2). This behavior of the peaks corresponds to a band gap closure mechanism that differs from the traditional one characteristic of 1D and 3D inhomogeneities. These effects can be explained by a peculiarity of the energy conservation laws for the incident and scattered waves for 2D inhomogeneities in a 1D superlattice.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Man'kov Y. I., Pozdnyakov A. V.
Заглавие : Spin-wave susceptibility of partially randomized ferromagnetic superlattices
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 89, Is. 4. - P717-722. - ISSN 1063-7761, DOI 10.1134/1.559033
Примечания : Cited References: 15
Предметные рубрики: SPECTRUM
LOCALIZATION
Аннотация: This paper is a theoretical investigation of the effect of inhomogeneities in the period of a ferromagnetic superlattice on the high-frequency superlattice susceptibility. The calculations are done for a model in which the uniaxial magnetic anisotropy is taken as the physical parameter that characterizes both the ideal superlattice and a partially randomized superlattice. It is found that as the inhomogeneities become more intense, the two resonance peaks corresponding to the splitting of the spectrum at the edge of the Brillouin zone of the superlattice broaden, move closer to each other, and finally merge into one. The height of this peak increases and the peak width decreases as the intensity of the inhomogeneities increases further. The effect of inhomogeneities on the susceptibility differs dramatically in the two limits of short- and long-wave inhomogeneities: in the latter case (in contrast to the former) the dependence of the separation of the susceptibility peaks on the intensity and correlation properties of the inhomogeneities is nonmonotonic. The possibility of observing these effects in spin-wave resonance experiments involving multilayer magnetic films is also discussed. (C) 1999 American Institute of Physics. [S1063-7761(99)01510-3].
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Maradudin A. A., Poszdnyakov A. V.
Заглавие : Waves in a superlattice with anisotropic inhomogeneities
Место публикации : JETP Letters. - 2003. - Vol. 78, Is. 9. - P.592-596. - ISSN 0021-3640, DOI 10.1134/1.1641491
Примечания : Cited References: 28
Предметные рубрики: PERIODIC MULTILAYERS
SPIN-WAVES
SPECTRUM
LOCALIZATION
SYSTEMS
MEDIA
DISORDER
AVERAGE
Аннотация: Dependences of the dispersion laws and damping of waves in an initially sinusoidal superlattice on inhomogeneities with anisotropic correlation properties are studied for the first time. The period of the superlattice is modulated by the random function described by the anisotropic correlation function K-phi(r) that has different correlation radii, k(parallel toparallel to)(-1) and k(perpendicular to)(-1), along the axis of the superlattice z and in the plane xy, respectively. The anisotropy of the correlation is characterized by the parameter lambda = 1 - k(perpendicular to)/k(parallel toparallel to) that can change from lambda = 0 to lambda = 1 when the correlation wave number k(perpendicular to) changes from k(perpendicular to) = k(parallel toparallel to) (isotropic 3D inhomogeneities) to k(perpendicular to) = 0 (1D inhomogeneities). The correlation function of the superlattice K(r) is developed. Its decreasing part goes to the asymptote L that divides the correlation volume into two parts, characterized by finite and infinite correlation radii. The dependences of the width of the gap in the spectrum at the boundary of the Brillouin zone Deltanu and the damping of waves xi on the value of lambda are studied. It is shown that decreasing L leads to the decrease of Deltanu, and increase of xi, with the increase of lambda. (C) 2003 MAIK "Nauka / Interperiodica".
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Laletin O. N.
Заглавие : Waves in a superlattice with arbitrary interlayer boundary thickness
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 12. - P2292-2300. - ISSN 1063-7834, DOI 10.1134/1.1841396
Примечания : Cited References: 34
Предметные рубрики: PERIODIC STRUCTURES
RAYLEIGH-WAVES
LAYERED MEDIUM
ELASTIC-WAVES
SPIN-WAVES
SPECTRUM
MEDIA
PROPAGATION
EXCITATIONS
MULTILAYERS
Аннотация: The transmittance D(omega), reflectance R(omega), and dispersion omega(k) are investigated for waves of various nature propagating through a one-dimensional superlattice (multilayer structure) with arbitrary thickness of the interlayer boundary. The dependences of the band gap widths Deltaomega(m) and their positions in the wave spectrum of the superlattice on the interlayer boundary thickness d and the band number m are calculated. Calculations are performed in terms of the modified coupled-mode theory (MCMT) using the frequency dependence of R(omega), as well as in the framework of perturbation theory using the function omega(k), which made it possible to estimate the accuracy of the MCMT method; the MCMT method is found to have a high accuracy in calculating the band gap widths and a much lower accuracy in determining the gap positions. It is shown that the m dependence of Deltaomega(m) for electromagnetic (or elastic) waves is different from that for spin waves. Furthermore, the widths of the band gaps with m = 1 and 2 are practically independent of d, whereas the widths of all gaps for m 2 depend strongly on d. Experimental measurements of these dependences allow one to determine the superlattice interface thicknesses by using spectral methods. (C) 2004 MAIK "Nauka/Interperiodica".
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klimin S. A., Kashchenko M. A., Bezmaternykh L. N.
Заглавие : Spin-phonon and electron-phonon interactions in multiferroic GdFe3(BO3)4 and TbFe3(BO3)4 evidenced by IR reflection spectroscopy
Коллективы : Russian Science Foundation [14-12-01033]; Swiss National Science Foundation (SNSF); Science and Technology cooperation program "Switzerland-Russia" of the University of Geneva
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.538-543. - ISSN 0022-2291, DOI 10.1007/s10909-016-1597-6. - ISSN 1573-7357(eISSN)
Примечания : Cited References:19. - The authors thank Alexey Kuzmenko and Marina Popova for fruitful discussions. This paper was supported by the Russian Science Foundation under Grant No. 14-12-01033, by the Swiss National Science Foundation (SNSF), and by the Science and Technology cooperation program "Switzerland-Russia" of the University of Geneva.
Предметные рубрики: PHASE-TRANSITIONS
GdFe3(BO3)4
CRYSTALS
SPECTRUM
Ключевые слова (''Своб.индексиров.''): multiferroics--ir-active phonons--spin-phonon interaction--coupled--electron-phonon mode
Аннотация: We study temperature-dependent polarized reflection spectra of multiferroic GdFe3(BO3)4 and TbFe3(BO3)4 single crystals. Signatures of spin–lattice interactions in both compounds and of a formation of the electron–phonon coupled mode in TbFe3(BO3)4 are discussed.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : The effective Hamiltonian of the singlet-triplet model for copper oxides
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2001. - Vol. 43, Is. 3. - P416-419. - ISSN 1063-7834, DOI 10.1134/1.1356113
Примечания : Cited References: 15
Предметные рубрики: HIGH-TC SUPERCONDUCTORS
BAND-STRUCTURE
LA2-XSRXCUO4
MECHANISM
SYMMETRY
SPECTRUM
Аннотация: The effective Hamiltonian for a realistic multiband p-d model is developed. In the case of electron doping, the Hamiltonian coincides with that for the standard t-J model. For hole doping, the singlet-triplet t-J model takes place. (C) 2001 MAIK "Nauka/Interperiodica".
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zyryanov V. Ya., Myslivets S. A., Gunyakov V. A., Parshin A. M., Arkhipkin V. G., Shabanov V. F., Lee, Wei
Заглавие : Magnetic-field tunable defect modes in a photonic-crystal/liquid-crystal cell
Место публикации : Opt. Express. - 2010. - Vol. 18, Is. 2. - P.1283-1288. - JAN 18. - ISSN 1094-4087, DOI 10.1364/OE.18.001283
Примечания : Cited Reference Count: 15. - Гранты: This work was partially supported by the Russian Federal Grant No. 02.740.11.0220 and SB RAS Grant Nos. 5, 27.1 and 144. W. Lee gratefully acknowledges financial support from the National Science Council of the Republic of China (Taiwan) under Grant No. NSC 98-2923-M-033-001-MY3 dedicated to an internationally joint effort between Russia and Taiwan.Финансирующая организация: Russian Federal [02.740.11.0220]; SB RAS [5, 27.1, 144]; National Science Council of the Republic of China (Taiwan) [NSC 98-2923-M-033-001-MY3]
Предметные рубрики: NEMATIC LIQUID-CRYSTAL
BAND-GAP MATERIALS
SPONTANEOUS EMISSION
SPECTRUM
Ключевые слова (''Своб.индексиров.''): crystal defects--magnetic fields--photonic crystals--applied magnetic fields--crossed polarizers--crystal cells--defect mode--homeotropic--light transmission spectra--light wave--nematic director--optical cells--planar alignment--spectral shift--tunable defect--light transmission--article--artifact--chemistry--electromagnetic field--liquid crystal--materials--materials testing--radiation exposure--refractometry--artifacts--electromagnetic fields--liquid crystals--manufactured materials--materials testing--refractometry
Аннотация: Light transmission spectrum of a multilayer photonic crystal with a central liquid-crystal defect layer placed between crossed polarizers has been studied. Transmittance was varied due to the magnetically induced reorientation of the nematic director from homeotropic to planar alignment. Two notable effects were observed for this scheme: the spectral shift of defect modes corresponding to the extraordinary light wave and its superposition with the ordinary one. As a result, the optical cell allows controlling the intensity of interfering defect modes by applied magnetic field. (C) 2010 Optical Society of America
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Effect of Interlayer Single-Particle Hoppings on the Superconducting Transition Temperature
Разночтения заглавия :авие SCOPUS: Effect of interlayer single-particle hoppings on the superconducting transition temperature
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 6. - P.339-343. - ISSN 0021-3640, DOI 10.1134/S0021364011060063
Примечания : Cited References: 27. - This work was supported by the Presidium of the Russian Academy of Sciences (program no. 18.7 "Quantum Physics of Condensed Matter"), by the Siberian and Ural Branches of the Russian Academy of Sciences (joint project no. 40), by the Russian Foundation for Basic Research (project no. 09-02-00127), by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. MK-1683.2010.2), and by the Ministry of Education and Science of the Russian Federation (project no. GK P891, federal program "Scientific and Pedagogical Personnel of Innovative Russia").
Предметные рубрики: T-J MODEL
DEPENDENCE
YBA2CU3O7-DELTA
ELECTRON
SPECTRUM
STRESS
Аннотация: It is well known that the superconducting transition temperature of high-T-c cuprates depends on the number of CuO2 planes in the unit cell. The multilayer structure implies the possibility of interlayer hopping. Under the assumption that the interlayer hopping can be specified by the parameter t(perpendicular to)(k) = t(perpendicular to)(cos(k(x)) - cos(k(y)))(2), the quasiparticle excitation spectrum for the bilayer cuprate in the superconducting state has been determined in the framework of the t - t' - t '' - t(perpendicular to) - J* model using the generalized mean-field approximation. It turns out that the interlayer hoppings does not create any additional mechanism of the Cooper paring and does not lead to an increase in T-c. The splitting of the upper Hubbard quasiparticle band attributed to the interlayer hoppings is manifested as two peaks in the doping dependence of the superconducting transition temperature at temperatures below the maximum T-c value for a single-layer cuprate. It has been found that antiferromagnetic interlayer correlations suppress the interlayer splitting. This probably leads to the common doping dependence of T-c for both single-layer and bilayer cuprates.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G., Shneider E. I.
Заглавие : Reconstruction of the Fermi surface of HTSC cuprates in a high magnetic field
Коллективы : Russian Foundation for Basic Research [09-02-00127]; Siberian Branch and the Ural Division, Russian Academy of Sciences [40]; Presidium of the Russian Academy of Sciences [5.7]
Место публикации : JETP Letters. - 2009. - Vol. 89, Is. 12. - P.632-637. - ISSN 0021-3640, DOI 10.1134/S002136400912008X
Примечания : Cited References: 19. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Siberian Branch and the Ural Division, Russian Academy of Sciences (integration project no. 40), and the Presidium of the Russian Academy of Sciences (program no. 5.7).
Предметные рубрики: T-J MODEL
COPPER OXIDES
ELECTRON
SPECTRUM
BAND
Аннотация: The effect of a high magnetic field on the electronic structure of HTSC cuprates is considered. The study is performed in the t-t'-taEuro(3)-J* model, and the high magnetic field effect is taken into account not only as the Zeeman splitting of the one-electron levels, but also in the occupation numbers of the states with different spin projections and in the formation of the spin correlation functions. The field is assumed to be high enough to align all of the spins along the field. As a result, the Fermi surface reconstruction is obtained from four hole pockets about the nodal point (pi/2, pi/2) in the paramagnetic phase to a large hole pocket about the point (pi, pi) in the ferromagnetic phase. As the magnetic field strength decreases, a number of quantum phase transitions are revealed; they are manifested in the changed Fermi surface topology. The Fermi surface reconstruction with a decreasing field is qualitatively the same as that with an increasing doping degree in the absence of a magnetic field.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Ovchinnikov S. G.
Заглавие : Temperature dependence of the electronic structure of La2CuO4 in the multielectron LDA+GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 121, Is. 3. - P.457-464. - ISSN 1063-7761, DOI 10.1134/S1063776115090174
Примечания : Cited References: 38. - The work was supported by the Russian Science Foundation (project no. 14-12-00061)
Предметные рубрики: Copper oxides
Model
Superconductivity
Excitations
Instability
Spectrum
States
Order
Аннотация: The band structure of La2CuO4 in antiferromagnetic and paramagnetic phases is calculated at finite temperatures by the multielectron LDA+GTB method. The temperature dependence of the band spectrum and the spectral weight of Hubbard fermions is caused by a change in the occupation numbers of local multielectron spin-split terms in the antiferromagnetic phase. A decrease in the magnetization of the sublattice with temperature gives rise to new bands near the bottom of the conduction band and the top of the valence band. It is shown that the band gap decreases with increasing temperature, but La2CuO4 remains an insulator in the paramagnetic phase as well. These results are consistent with measurements of the red shift of the absorption edge in La2CuO4 with increasing temperature. © 2015, Pleiades Publishing, Inc.
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