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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arkhipkin V. G., Timofeev I. V.
Заглавие : Adiabatic propagation of short pulses under conditions of electromagnetically induced transparency
Место публикации : Quantum Electron.: Turpion LTD, 2000. - Vol. 30, Is. 2. - P.180-184. - ISSN 1063-7818, DOI 10.1070/QE2000v030n02ABEH001683
Примечания : Cited References: 31
Предметные рубрики: POPULATION TRANSFER
LASER-PULSES
INTERFERENCE
ENHANCEMENT
COHERENCE
QUANTUM
SYSTEMS
INDEX
Аннотация: The spatial and temporal dynamics of two short pulses propagating in an optically dense medium of resonant three-level Lambda-atoms is investigated numerically and analytically. The maximum coherence for the Raman transition due to coherent population trapping. it is shown that, at the initial stage of propagation, the waveforms of such pulses only slightly change along the length of the medium, which may considerably exceed the length of linear absorption for a single weak pulse. As the length of the absorbing medium increases, the energy of the probe (first) pulse is completely transferred into the second (control) pulse.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Anomalies in transport properties in a magnetically ordered region on a Kondo lattice
Место публикации : JETP Letters. - 2005. - Vol. 81, Is. 2. - P.66-71. - ISSN 0021-3640, DOI 10.1134/1.1887917
Примечания : Cited References: 33
Предметные рубрики: DOUBLE EXCHANGE MODEL
PHASE-SEPARATION
MANGANITES
LA1-XSRXMNO3
SYSTEMS
SHIFT
EDGE
Аннотация: The temperature dependences of resistivity and thermal emf on a Kondo lattice are calculated using the spinpolaron approximation. The peaks and sign reversal points of thermal emf as a function of temperature and concentration below the temperature of the transition to the paramagnetic state are determined. The concentration region containing the metal-insulator transition below the Curie temperature and the shift of the upper spin-polaron band are calculated. (c) 2005 Pleiades Publishing, Inc.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Valkov V. V.
Заглавие : Anomalous resistivity and superconductivity in the two-band Hubbard model with one narrow band (Review)
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 1. - P.69-82. - ISSN 1063-777X, DOI 10.1063/1.3552118; \b Физика низких температур
Примечания : Cited References: 62. - We thank A.S. Alexandrov, A.F. Andreev, M.A. Baranov, Yu. Bichkov, A.V. Chubukov, D.V. Efremov, A.S. Hewson, K.A. Kikoin, F.V. Kusmartsev, P. Nozieres, T.M. Rice, A.O. Sboychakov, P. Thalmeer, C.M. Varma, D. Vollhardt, P. Woelfle, A. Yaresko and, especially, P. Fulde, Yu. Kagan, K.I. Kugel, and N.V. Prokof'ev for many simulating discussions on this subject and acknowledge the financial support of RFBR grants # 08-02-00224 and 08-02-00212. M.Yu.K. is also grateful to the Leverhulme trust for a grant to visit Loughborough University, where this work was completed.
Предметные рубрики: FERMI-LIQUID BEHAVIOR
MAGNETIC-ALLOYS
HEAVY
DENSITY
SYSTEMS
STATE
UPT3
MECHANISM
PARTICLE
VALENCE
Аннотация: We search for marginal Fermi-liquid behavior in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron-polaron effects and other mechanisms for mass-enhancement (related to the momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find a tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case with a large mismatch between the densities of heavy and light bands in the strong coupling limit. We also find that for low temperatures and equal densities, the resistivity in a homogeneous state R(T) proportional to T-2 behaves as a Fermi-liquid in both 3D and 2D. For temperatures greater than the effective bandwidth for heavy electrons T W-h*, the coherence of the heavy component breaks down completely. The heavy particles move diffusively in the surrounding light particles. At the same time, light particles scatter on heavy particles as if on immobile (static) impurities. Under these conditions, the heavy component is marginal, while the light component is not. The resistivity approaches saturation for T W-h* in the 3D case. In 2D the resistivity has a maximum and a localization tail owing to weak-localization corrections of the Altshuler-Aronov type. This behavior of resistivity in 3D could be relevant for some uranium-based heavy-fermion compounds such as UNi2Al3 and in 2D, for some other mixed-valence compounds, possibly including layered manganites. We also consider briefly the superconductive (SC) instability in this model. The leading instability tends to p-wave pairing and is governed by an enhanced Kohn-Luttinger mechanism for SC at low electron densities. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light electrons in 2D. (C) 2011 American Institute of Physics. [doi:10.1063/1.3552118]
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2012. - Vol. 25, Is. 5. - P.1379-1382. - ISSN 1557-1939, DOI 10.1007/s10948-012-1523-3
Примечания : Cited References: 28. - We are grateful to P. Fulde, Yu. Kagan, K. I. Kugel, N.V. Prokof'ev, P. Nozieres, and C. M. Varma for the numerous stimulating discussions. We acknowledge financial support of the RFBR Grant No. 11-02-00741.
Предметные рубрики: FERMI GAS
SUPERCONDUCTIVITY
SUPERFLUIDITY
TEMPERATURE
REPULSION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): electron-polaron effect--two-band hubbard model--marginality--anomalous resistivity
Аннотация: We search for anomalous normal and superconductive behavior in the two-band Hubbard model with one narrow band. We analyze the influence of the electron–polaron effect and the Altshuler–Aronov effect on effective mass enhancement and scattering times of heavy and light components in the clean case. We find anomalous behavior of resistivity at high temperatures TW∗hT W_{h}. *} both in 3D and 2D situations. The SC instability in the model is governed by an enhanced Kohn–Luttinger effect for p-wave pairing of heavy electrons via polarization of light electrons.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Pilipchuk A. S.
Заглавие : Bound states in the continuum in zigzag quantum wire enforced by a finger gate
Коллективы : Russian Foundation for Basic Research [14-12-00266]
Место публикации : JETP Letters. - 2015. - Vol. 100, Is. 9. - P.585-590. - ISSN 0021, DOI 10.1134/S0021364014210139. - ISSN 10906487(eISSN)
Примечания : Cited References:41. - This work was supported by the Russian Foundation for Basic Research(project no. 14-12-00266).
Предметные рубрики: WAVE-GUIDE
DOUBLE-BEND
SYSTEMS
TRANSMISSION
RESONANCES
ELECTRON
Аннотация: We consider electron transport in a zigzag quantum wire by the effect of finger gate potential. Using a non-Hermitian effective Hamiltonian, we calculate resonance positions and widths to show that the resonance widths are easily governed by the gate potential. In particular, the resonance width can be enforced to be equal to zero, which leads to an electron localization with the Fermi energy embedded in the propagation band of the wire, i.e., the bound state in the continuum (BSC). We show that, for positive values of the potential, a zigzag wire becomes a Fabry-Perot resonator to give rise to BSC too.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kaptsov O. V., Zabluda A. V.
Заглавие : Characteristic invariants and Darboux's method
Место публикации : J. Phys. A. - 2005. - Vol. 38, Is. 14. - P.3133-3144. - ISSN 0305-4470, DOI 10.1088/0305-4470/38/14/005
Примечания : Cited References: 22
Предметные рубрики: PARTIAL-DIFFERENTIAL-EQUATIONS
MOVING COFRAMES
SYSTEMS
Аннотация: We develop a method that allows us to derive reductions and solutions to hyperbolic systems of partial differential equations. The method is based on using functions that are constant in the direction of characteristics of the system. These functions generalize well-known Riemann invariants. As applications we consider the gas dynamics system and ideal magnetohydrodynamics equations. In special cases, we find solutions of these equations depending on some arbitrary functions.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Cluster perturbation theory in Hubbard model exactly taking into account the short-range magnetic order in 2 x 2 cluster
Коллективы :
Разночтения заглавия :авие SCOPUS: Cluster perturbation theory in Hubbard model exactly taking into account the short-range magnetic order in 2 × 2 cluster
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 111, Is. 4. - P635-644. - ISSN 1063-7761, DOI 10.1134/S1063776110100146
Примечания : Cited References: 23. - The authors thank V. V. Val'kov for fruitful discussions of this work. This research was supported financially by the Russian Foundation for Basic Research (project nos. 09-02-90723-mob_st and 09-02-00127) and by program no. 5.7 of the Presidium of the Russian Academy of Sciences and integration project no. 40 of the Siberian Branch and Ural Division of the Russian Academy of Sciences.
Предметные рубрики: INFINITE DIMENSIONS
SYSTEMS
STATE
Ключевые слова (''Своб.индексиров.''): antiferromagnetic orders--characteristic energy--cluster perturbation theories--coulomb repulsions--density of state--dynamic mean field theories--eigenvalue problem--exact diagonalization--excited levels--finite temperatures--half-filling--hubbard--metal insulator transition temperature--nearest neighbors--numerical solution--pseudo-gap--quasiparticle spectrum--shadow zone--short-range magnetic orders--temperature evolution--zero temperatures--antiferromagnetism--eigenvalues and eigenfunctions--fermi level--hubbard model--mean field theory--metal insulator boundaries--perturbation techniques--semiconductor insulator boundaries--statistical mechanics--metal insulator transition
Аннотация: The cluster perturbation theory is presented in the 2D Hubbard model constructed using X operators in the Hubbard-I approximation. The short-range magnetic order is taken into account by dividing the entire lattice into individual 2 x 2 clusters and solving the eigenvalue problem in an individual cluster using exact diagonalization taking into account all excited levels. The case of half-filling taking into account jumps between nearest neighbors is considered. As a result of numerical solution, a shadow zone is discovered in the quasiparticle spectrum. It is also found that a gap in the density of states in the quasiparticle spectrum at zero temperature exists for indefinitely small values of Coulomb repulsion parameter U and increases with this parameter. It is found that the presence of this gap in the spectrum is due to the formation of a short-range antiferromagnetic order. An analysis of the temperature evolution of the density of states shows that the metal-insulator transition occurs continuously. The existence of two characteristic energy scales at finite temperatures is demonstrated, the larger scale is associated with the formation of a pseudogap in the vicinity of the Fermi level, and the smaller scale is associated with the metal-insulator transition temperature. A peak in the density of states at the Fermi level, which is predicted in the dynamic mean field theory in the vicinity of the metal-insulator transition, is not observed.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krinitsyn A., Nikolaev S., Ovchinnikov S. G.
Заглавие : Cluster size and shape effect on the electronic structure of the Hubbard model within the norm-conserving cluster perturbation theory
Коллективы : Siberian Federal University [F-11]; Presidium of RAS Program [20.7]; [NSh-1044.2012.2]; [MK-1168.2012.2]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2014. - Vol. 27, Is. 4. - P.955-963. - ISSN 1557-1939, DOI 10.1007/s10948-013-2418-7. - ISSN 1557-1947
Примечания : Cited References: 59. - This work was supported by Grants NSh-1044.2012.2 and MK-1168.2012.2, Siberian Federal University: Grant F-11, and the Presidium of RAS Program 20.7.
Предметные рубрики: NARROW ENERGY-BANDS
CUPRATE SUPERCONDUCTORS
PHOTOEMISSION SPECTRA
PSEUDOGAP
ANTIFERROMAGNET
EXCITATIONS
EVOLUTION
SYSTEMS
PHASE
STATE
Ключевые слова (''Своб.индексиров.''): cluster perturbation theory--hubbard model--strong correlations--density of states--fermi surface
Аннотация: Within a new norm-conserving approach to the cluster perturbation theory (CPT) for the 2d Hubbard model we study the effect of the cluster size and shape on the electronic structure. We have compared two type of clusters, 4-cluster (2x2) and 5-cluster (cruciform of 5 atoms). With 4-cluster we can treat exactly the first and second neighbours correlations, C (1) and C (2). With 5-cluster the third neighbour correlations C (3) are also treated exactly. The band structure in the CPT with 4- and 5-clusters differs remarkably. The quasiparticle spectral weight map for 5-clusters is very similar to the Quantum Monte Carlo (QMC) and the variational CPT data. With increasing doping, small hole Fermi surface transforms into conventional Fermi-liquid type large Fermi surface through Lifshitz quantum phase transitions.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Crossing resonance of stochastically interacting wave fields
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 116, Is. 2. - P.206-222. - ISSN 1063-7761, DOI 10.1134/S1063776113020118
Примечания : Cited References: 42. - We are grateful to V. V. Val'kov and A. F. Sadreev for useful discussions. This work was supported by the Presidium of the Russian Academy of Sciences (Program no. 24.29), the Dynasty Foundation (Program for Support of Young Scientists), the Federal Target Program (state contract no. 14.B37.21.0730), and the Special Program for Siberian Federal University of the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CRYSTALS
SYSTEMS
ALLOYS
MEDIA
Аннотация: The dynamic susceptibilities (Green's functions) of the system of two interacting wave fields of different physical natures with a stochastically inhomogeneous coupling parameter between them with zero mean value have been examined. The well-known self-consistent approximation taking into account all diagrams with noncrossing correlation/interaction lines has been generalized to the case of stochastically interacting wave fields. The analysis has been performed for spin and elastic waves. The results obtained taking into account the processes of multiple scattering of waves from inhomogeneities are significantly different from those obtained for this situation earlier in the Bourret approximation [R.C. Bourret, Nuovo Cimento 26, 1 (1962)]. Instead of frequencies degeneracy removal in the wave spectrum and the splitting of resonance peaks of dynamic susceptibilities, a wide single-mode resonance peak should be observed at the crossing point of the unperturbed dispersion curves. The fine structure appears at vertices of these wide peaks in the form of a narrow resonance on the Green's-function curve of one field and a narrow antiresonance on the vertex of the Green's-function curve of the other field.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : Decay of multispin multiquantum coherent states in the NMR of a solid
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 3. - P451-459. - ISSN 1063-7761, DOI 10.1134/S1063776111020129
Примечания : Cited References: 24
Предметные рубрики: SYSTEMS
SPECTRA
Ключевые слова (''Своб.индексиров.''): adiabatic approximations--andersons--coherent state--dynamic phenomena--experimental data--local fields--model-based--radiospectroscopy--relaxation functions--spin precession--theoretical result--two-component--coherent light
Аннотация: A model based on the Anderson adiabatic approximation, which is widely used for describing various aspects of dynamic phenomena in conventional radiospectroscopy, is proposed for describing the decay of multispin multiquantum coherent states in a solid. The coherent state relaxation function is represented by the product of two functions corresponding to spin precession in a two-component local field with a correlated and an uncorrelated component. Theoretical results of this study explain the experimental data reported in a number of publications and are in good agreement with these data.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lundin A. A., Zobov V. E.
Заглавие : Decoherence-induced stabilization of the multiple-quantum NMR-spectrum width
Место публикации : Appl. Magn. Reson.: Springer, 2016. - Vol. 47, Is. 7. - P.701-710. - ISSN 0937-9347, DOI 10.1007/s00723-016-0770-z. - ISSN 1613-7507(eISSN)
Примечания : Cited References:26
Предметные рубрики: SIMULATIONS
DYNAMICS
SYSTEMS
SOLIDS
Аннотация: The time dependence of an increase in the number of correlated spins in cluster was calculated for a particular variant of multiple-quantum (MQ) nuclear magnetic resonance spectroscopy using an effective two-quantum Hamiltonian that includes conventional secular nuclear dipole-dipole interaction as a weak perturbation at the stage of correlation preparation. It was shown that the cluster size grows steadily, while the width of the MQ spectrum stabilizes because the decay rates of the spectral components located at different areas of the MQ spectrum are different. The MQ bandwidth was also calculated as a function of the preparation time for various perturbation strengths. The results obtained are in excellent agreement with the experimental data reported in Alvarez and Suter (Phys Rev A 84:012320, 2011).
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Dimerization of antiferromagnetic chain with 4-spin interaction
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 38, Is. 6. - P1868-1877. - ISSN 0367-3294
Примечания : Cited References: 30
Предметные рубрики: SPIN-1/2 HEISENBERG-ANTIFERROMAGNET
COMPETING INTERACTIONS
MONTE-CARLO
THERMODYNAMIC PROPERTIES
SYSTEMS
CUGEO3
TEMPERATURE
NEUTRON
STATE
MODEL
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-T-c copper oxides
Разночтения заглавия :авие SCOPUS: Doping-dependent evolution of low-energy excitations and quantum phase transitions within an effective model for high-T c copper oxides
Место публикации : Eur. Phys. J. B: SPRINGER, 2007. - Vol. 57, Is. 3. - P271-278. - ISSN 1434-6028, DOI 10.1140/epjb/e2007-00179-2
Примечания : Cited References: 49
Предметные рубрики: ELECTRON CORRELATIONS
HUBBARD-MODEL
RANGE-ORDER
DIMENSIONS
WAVE
FERMIONS
SYSTEMS
BANDS
METAL
Ключевые слова (''Своб.индексиров.''): doping dependent evolution--kinematic correlation functions--low energy excitations--quantum phase transitions--doping (additives)--electric excitation--mean field theory--parameter estimation--phase transitions--quantum theory--copper oxides
Аннотация: In this paper a mean-field theory for the spin-liquid paramagnetic non-superconducting phase of the p- and n-type high-T-c cuprates is developed. This theory applied to the effective t-t'-t ''-J* model with the ab initio calculated parameters and with the three-site correlated hoppings. The static spin-spin and kinematic correlation functions beyond Hubbard-I approximation are calculated self-consistently. The evolution of the Fermi surface and band dispersion is obtained for the wide range of doping concentrations x. For p-type systems the three different types of behavior are found and the transitions between these types are accompanied by the changes in the Fermi surface topology. Thus a quantum phase transitions take place at x = 0.15 and at x = 0.23.Due to the different Fermi surface topology we found for n-type cuprates only one quantum critical concentration, x = 0.2. The calculated doping dependence of the nodal Fermi velocity and the effective mass are in good agreement with the experimental data.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : BERMAN G., Bulgakov E. N., HOLM D., KLUGER Y.
Заглавие : DYNAMICAL CHAOS IN SU(2) CIRCLE-TIMES-U (1) THEORY
Место публикации : Phys. Lett. A: ELSEVIER SCIENCE BV, 1994. - Vol. 194, Is. 4. - P251-264. - ISSN 0375-9601, DOI 10.1016/0375-9601(94)91247-5
Примечания : Cited References: 26
Предметные рубрики: GAUGE-THEORY
SYSTEMS
FIELDS
Аннотация: We study the dynamics of the classical homogeneous SU(2) x U(1) gauge theory in the spontaneously broken phase. A transition from regular to chaotic dynamics is shown to occur for energy densities epsilon 0.3m(w)2/G(F) almost-equal-to 2 x 10(10) GeV/fm3. The regular regime is characterized by a sharp frequency spectrum for the Yang-Mills fields. The frequency spectrum in the chaotic regime is continuous and the sharp frequency lines of the regular regime are dispersed. In the early universe or at high energy densities in a Yang-Mills plasma this transition may have observable effects that can be studied by analyzing the frequency spectrum and the time correlation functions. In the chaotic regime these time correlation functions decay considerably faster than in the regular regime.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I.
Заглавие : Effect of the correlation properties of one- and three-dimensional inhomogeneities on the high-frequency magnetic susceptibility of sinusoidal superlattices
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 3. - P587-594. - ISSN 1063-7834, DOI 10.1134/1.1884725
Примечания : Cited References: 29
Предметные рубрики: PERIODIC MULTILAYERS
WAVE SPECTRUM
SPIN-WAVES
LOCALIZATION
SYSTEMS
DISORDER
Аннотация: The effect of one-(1D) and three-dimensional (3D) inhomogeneities on the high-frequency magnetic susceptibility at the boundary of the first Brillouin zone of a ferromagnetic superlattice is studied. The study is performed with an earlier developed method of random spatial modulation (RSM) of the superlattice period. In this method, structural inhomogeneities are described in terms of the random-phase model, in which the phase depends on three coordinates in the general case. The frequency spacing Delta v(m) between two peaks in the imaginary part of the averaged Green's function, which characterizes the gap width in the frequency spectrum at the boundary of the Brillouin zone, is calculated as a function of both the root-mean-square fluctuations gamma(i) and the correlation wavenumbers eta(i) of phase inhomogeneities (i = 1 and 3 for 1D and 3D inhomogeneities, respectively). The function Delta v(m)(gamma(1), eta(1)) for 1D inhomogeneities is shown to be symmetric with respect to inter- changing the variables gamma(1)(2) and eta(1), whereas the function Delta v(m)(gamma(3), eta(3)) for 3D inhomogeneities is strongly asym- metric with respect to interchanging gamma(3)(2) eta(3). This effect is associated with the difference in form between the correlation functions of 1D and 3D inhomogeneities and can be used to determine the dimensionality of inhomogeneities from the results of spectral studies of such superlattices. (c) 2005 Pleiades Publishing, Inc.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pichugin K., Schanz H., Seba P.
Заглавие : Effective coupling for open billiards
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2001. - Vol. 64, Is. 5. - Ст.56227. - ISSN 1063-651X, DOI 10.1103/PhysRevE.64.056227
Примечания : Cited References: 30
Предметные рубрики: QUANTUM CHAOTIC SCATTERING
MICROWAVE CAVITY
RESONANCE POLES
QUANTIZATION
STATISTICS
DYNAMICS
FORMULA
SYSTEMS
STATES
Аннотация: We derive an explicit expression for the coupling constants of individual eigenstates of a closed billiard that is opened by attaching a waveguide. The Wigner time delay and the resonance positions resulting from the coupling constants are compared to an exact numerical calculation. Deviations can be attributed to evanescent modes in the waveguide and to the finite number of eigenstates taken into account. The influence of the shape of the billiard and of the boundary conditions at the mouth of the waveguide are also discussed. Finally we show that the mean value of the dimensionless coupling constants tends to the critical value when the eigenstates of the billiard follow random-matrix theory.
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17.

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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I., Maradudin A. A.
Заглавие : Effects of one- and three-dimensional inhomogeneities on the wave spectrum of multilayers with finite interface thicknesses
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2002. - Vol. 65, Is. 2. - Ст.24207. - ISSN 1098-0121, DOI 10.1103/PhysRevB.65.024207
Примечания : Cited References: 24
Предметные рубрики: PERIODIC MULTILAYERS
SPIN-WAVES
LOCALIZATION
SUPERLATTICES
SYSTEMS
DISORDER
AVERAGE
MEDIA
Аннотация: To describe a partially randomized multilayer structure with arbitrary thicknesses of the interfaces between layers, we introduce a model in which the dependence of a material parameter along the axis of such a Superlattice is described by a Jacobian elliptic sine function with a random spatial modulation of its period. Both one- and three-dimensional inhomogeneities of the period are considered. We develop the correlation function for this model, and investigate the dispersion law and damping of averaged waves in this superlattice. The dependencies of the widths of the gaps in the spectrum and the damping at the boundaries of all odd Brillouin zones, on the thicknesses of the interfaces, and on the dimensionality, intensity, and correlation wave number of the inhomogeneities are found. It is shown that experimental investigations of the widths of the gaps and damping for several Brillouin zones could permit, in principle, determining all parameters of the superlattice as well as the parameters of the inhomogeneities from these spectral characteristics.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I., Maradudin A. A.
Заглавие : Effects of the dimensionality of inhomogeneities on the wave spectrum of superlattices
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2003. - Vol. 68, Is. 2. - Ст.24209. - ISSN 1098-0121, DOI 10.1103/PhysRevB.68.024209
Примечания : Cited References: 26
Предметные рубрики: ELASTIC MEDIUM THEORY
PERIODIC MULTILAYERS
SPIN-WAVES
LOCALIZATION
SYSTEMS
MEDIA
DISORDER
Аннотация: Dependences of the dispersion laws and damping of waves in an initially sinusoidal superlattice on the dimensionality of inhomogeneities modulating the period of the superlattice are studied. The cases of one- and three-dimensional modulations, as well as modulation by a mixture of inhomogeneities of both of these dimensionalities, are considered. The correlation function of the superlattice K(r) has the form of a product of the same periodic function and a decreasing function that is significantly different for these different cases. For r -- infinity the decreasing function goes to zero for the one-dimensional inhomogeneities and to a nonzero asymptote for the three-dimensional ones. Consequently, the transition from the disordered to ordered states is accompanied in the three-dimensional case not only by an increase of the correlation radius as in the one-dimensional case, but also by a change in the relationship between the volumes of the superlattices with finite and infinite correlation radii. The decreasing part of the correlation function for the mixture of inhomogeneities of different dimensionalities has the form of a product of the decreasing parts of the correlation functions of the components of the mixture. This leads to the nonadditivity of the contributions of the components of different dimensionalities to the resulting modification of the parameters of the wave spectrum that are due to the inhomogeneities (the damping of waves for the mixture of these components is smaller than the sum of the dampings of the components, the maximum gap in the spectrum corresponds to the simultaneous presence of both components, and so on).
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I., Maradudin A. A.
Заглавие : Effects of the mixture of one- and three-dimensional inhomogeneities on the wave spectrum of superlattices
Место публикации : JETP Letters. - 2003. - Vol. 77, Is. 6. - P.285-290. - ISSN 0021-3640, DOI 10.1134/1.1577758
Примечания : Cited References: 24
Предметные рубрики: PERIODIC MULTILAYERS
SPIN-WAVES
LOCALIZATION
SYSTEMS
THICKNESSES
DISORDER
AVERAGE
MEDIA
Аннотация: Dependences of the dispersion laws and damping of waves in an initially sinusoidal superlattice on the dimensionality of inhomogeneities modulating the period of the superlattice are studied. The cases of one- and three-dimensional modulations, as well as modulation by a mixture of inhomogeneities of both of these dimensionalities, are considered. The correlation function of the superlattice K(r) has the form of a product of the same periodic function and a decreasing function that is significantly different for these different cases. The decreasing part of the correlation function for the mixture of inhomogeneities of different dimensionalities has the form of a product of the decreasing parts of the correlation functions of the components of the mixture. This leads to the nonadditivity of the contributions of the components of different dimensionalities to the resulting modification of the parameters of the wave spectrum that are due to the inhomogeneities (the damping of waves for the mixture of these components is smaller than the sum of the dampings of the components, the maximum gap in the spectrum corresponds to the simultaneous presence of both components of the mixture, not only of the three-dimensional inhomogeneities). (C) 2003 MAIK "Nauka / Interperiodica".
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