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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Pichugin K. N., Sadreev A. F.
Заглавие : Symmetry breaking for transmission in a photonic waveguide coupled with two off-channel nonlinear defects
Место публикации : Phys. Rev. B: American Physical Society, 2011. - Vol. 83, Is. 4. - Ст.45109. - ISSN 1098-0121, DOI 10.1103/PhysRevB.83.045109
Примечания : Cited References: 50. - This work was partially supported by RFBR Grant No. 09-02-98005-"Siberia" and RFBR Grant No. 11-02-00289.
Предметные рубрики: CRYSTAL-CIRCUITS
LOCALIZED MODES
BISTABILITY
IMPURITIES
RESONANCE
CAVITIES
STATES
MEDIA
Аннотация: We consider light transmission in a two-dimensional (2D) photonic crystal waveguide coupled with two identical nonlinear defects positioned symmetrically aside the waveguide. With the coupled mode theory, we show three scenarios for the transmission. The first one inherits the linear case and preserves the symmetry. In the second scenario, the symmetry is broken because of different light intensities at the defects. In the third scenario, the intensities at the defects are equal but phases of complex amplitudes are different. That results in a vortical power flow between the defects similar to the dc Josephson effect if the input power over the waveguide is applied and the defects are coupled. All of these phenomena agree well with computations based on an expansion of the electromagnetic field into optimally adapted photonic Wannier functions in a 2D photonic crystal.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Terent'yev K. Yu., Gokhfeld D. M., Petrov M. I.
Заглавие : Fractal dimension of cluster boundaries in porous polycrystalline HTSC materials
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 10. - P.1947-1950. - ISSN 1063-7834, DOI 10.1134/S1063783412100095
Примечания : Cited References: 20
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
ELECTRICAL-CONDUCTIVITY
PERCOLATION
MIXTURES
MEDIA
SUPERCONDUCTORS
TRANSPORT
SPHERES
Аннотация: The fractal dimension of the boundaries of clusters formed by pores and granules in polycrystalline materials is shown to be determined by the sample density and crystallite sizes. The dependence of the fractal dimension on the density has a maximum. It is shown that the maximum diamagnetic response can be obtained in a porous high-temperature superconductor with a porosity of 50-60% and small crystallite sizes.
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3.

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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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vetrov S. Y., Bikbaev R. G., Timofeev I. V.
Заглавие : Optical Tamm states at the interface between a photonic crystal and a nanocomposite with resonance dispersion
Коллективы : Ministry of Education and Science of the Russian Federation [14.V37.21.0730, 14V37.21.0730]; Presidium of the Siberian Branch, Russian Academy of Sciences [24.29]; Division of Physical Sciences, Russian Academy of Sciences [Sh.9.5]; Presidium of the Russian Academy of Sciences [24.29, 24.31]; Siberian Branch, Russian Academy of Sciences [43, 101]
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2013. - Vol. 117, Is. 6. - P.988-998. - ISSN 1063-7761, DOI 10.1134/S1063776113140185. - ISSN 1090-6509
Примечания : Cited References: 28. - This work was supported by the Ministry of Education and Science of the Russian Federation (state contract no. 14.V37.21.0730, federal program "Human Capital for Science and Education in Innovative Russia"); by the Presidium of the Siberian Branch, Russian Academy of Sciences (project no. 24.29); by the Ministry of Education and Science of the Russian Federation (contract no. 14V37.21.0730); by the Division of Physical Sciences, Russian Academy of Sciences (project no. Sh.9.5); by the Presidium of the Russian Academy of Sciences (project nos. 24.29 and 24.31); and by the Siberian Branch, Russian Academy of Sciences (project nos. 43 and 101).
Предметные рубрики: LIGHT
TRANSMISSION
MEDIA
LAYER
Аннотация: Optical Tamm states localized at the edges of a photonic crystal bounded from one or both sides by a nanocomposite have been studied. The nanocomposite consists of metallic nanoinclusions, which have a spherical or orientationally ordered spheroidal shape and are dispersed in a transparent matrix, and is characterized by the resonant effective permittivity. The transmission, reflection, and absorption spectra have been calculated for waves with longitudinal and transverse polarizations in such structures at the normal incidence of light. The spectral manifestation of Tamm states that is due to the existence of negative values of the real part of the effective permittivity has been analyzed for the visible spectral range. It has been established that the characteristics of Tamm states localized at the edge of the photonic crystal depend strongly both on the concentration of nanoballs in the nanocomposite film and on its thickness. Modes formed by two coupled Tamm plasmon polaritons localized at the edges of the photonic crystal adjacent to two nanocomposite layers have been examined. It has been shown that, in the case of the anisotropic nanocomposite layer adjacent to the photonic crystal, each of two orthogonal polarizations of the incident wave corresponds to a specific frequency of the Tamm state localized at the edge; owing to this property, the transmission spectra of such a structure are polarization sensitive.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vetrov S.Ya., Avdeeva A. Y., Bikbaev R. G., Timofeev I. V.
Заглавие : Traveling of light through a 1D photonic crystal containing a defect layer with resonant dispersion
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 113, Is. 5. - P.517-521. - ISSN 0030-400X, DOI 10.1134/S0030400X12110070
Примечания : Cited References: 14. - The work was supported by the grants NSh-7810.2010.3, RNP.2.1.1.3455, no. 27.1 and no. 3.9.1 RAS, no. 5 and no. 144 SO RAS, and g/k 02.740.11.0220 of the federal targeted program "Scientific and Pedagogical Personnel of Innovative Russia."
Предметные рубрики: 2ND-HARMONIC GENERATION
MEDIA
MODE
Аннотация: Spectral properties of a 1D photonic crystal that is comprised of two multilayered dielectric mirrors and a nanocomposite layer between them as a structural defect are studied. The nanocomposite consists of silver nanoballs dispersed in a transparent matrix and is characterized by an effective resonant permittivity. The spectral manifestation of the defect mode splitting for the s-polarized waves is studied as a function of the angle of incidence and concentration of nanoballs. Specific features of the transmission spectra for the s- and p-polarized waves are established for the angle of incidence equal to the Brewster angle of the seeding photonic crystal. It is shown, in particular, that, in the region of the continuous transmission spectrum of the spolarized waves, there arises an additional bandgap caused by mixing of the resonant mode with photonic modes.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vetrov S.Ya., Pyatnov M. V., Timofeev I. V.
Заглавие : Photonic defect modes in a cholesteric liquid crystal with a resonant nanocomposite layer and a twist defect
Коллективы : SB RAS [43, 101, 24.29]; Russian Fund of Fundamental Research Grant [14-02-31248]; Russian Ministry of Education and Science under the Government program [3.1276.2014/K]; Russian Federation [MK-250.2013.2]; NSCT-SB RAS joint project
Место публикации : Phys. Rev. E: American Physical Society, 2014. - Vol. 90, Is. 3. - Ст.32505. - ISSN 1539-3755, DOI 10.1103/PhysRevE.90.032505. - ISSN 1550-2376
Примечания : Cited References: 36. - This work was partially supported by Grants No. 43, No. 101, and No. 24.29 of SB RAS; Russian Fund of Fundamental Research Grant No. 14-02-31248; Russian Ministry of Education and Science under the Government program, Project No. 3.1276.2014/K; Grant of the President of the Russian Federation Grant No. MK-250.2013.2, and the NSCT-SB RAS joint project.
Предметные рубрики: OPTICAL-PROPERTIES
GENERATION
MEDIA
FILMS
Аннотация: We have studied spectral properties of a cholesteric liquid crystal with a combined defect consisting of a nanocomposite layer and a twist. The nanocomposite layer is made of metallic nanoballs dispersed in a transparent matrix and featuring effective resonant permittivity. A solution has been found for the transmission spectrum of circularly polarized waves in the structure. We have analyzed spectral splitting of the defect mode in the band gap of the cholesteric when its frequency coincides with the nanocomposite resonant frequency. Defect modes have characteristics strongly dependent on the magnitude and the sign of the phase difference of the cholesteric helix on both sides of the defect layer. It has been found that the band gap width and the position and localization degree of defect modes can be effectively controlled by external fields applied to the cholesteric.
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Arkhipkin V. G., Timofeev I. V.
Заглавие : Propagation of two short pulses under conditions of electromagnetically induced transparency: adiabatic following
Коллективы : International Workshop/Fall School Meeting for Young Scientists and Students on Optics, Laser Physics, and Biophysics (Saratov Fall Meeting 99) (1999 ; Oct.; Saratov)
Место публикации : Saratov fall meeting '99: Laser physics and spectroscopy. Ser. Proceedings of the society of photo-optical instrumentation engineers (SPIE): SPIE-Int. Soc. Optical Engineering, 2000. - Vol. 4002. - P.45-51. - ISBN 0277-786X, DOI 10.1117/12.380132. - ISBN 0-8194-3627-5
Примечания : Cited References: 31
Предметные рубрики: POPULATION TRANSFER
LASER-PULSES
QUANTUM
COHERENCE
MEDIA
INDEX
INTERFERENCE
ENHANCEMENT
TRANSITIONS
REFRACTION
Ключевые слова (''Своб.индексиров.''): electromagnetically-induced transparency--coherent population trapping--atomic coherence--quantum interference--adiabatic following--dressed field pulses
Аннотация: Spatio-temporal dynamics of two short laser pulses propagating in an absorbing medium, which consists of one-and two-photon resonant ii-atoms, is investigated in the adiabatic approximation. We give an analytical solution and compare it with numerical simulations. It is shown that pulses may propagate in a medium, whose thickness is considerably greater than the length of the linear absorption of a single weak probe wave. Finally, full transfer of the probe pulse energy into the coupling pulse takes place. A vector model of the adiabatic interaction of two pulses with three-level atom is proposed.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arkhipkin V. G., Timofeev I. V.
Заглавие : Temporal shape manipulation of intense light pulses by coherent population trapping
Место публикации : Phys. Rev. A: American physical society, 2006. - Vol. 73, Is. 2. - Ст.25803. - ISSN 1050-2947, DOI 10.1103/PhysRevA.73.025803
Примечания : Cited References: 37
Предметные рубрики: ELECTROMAGNETICALLY INDUCED TRANSPARENCY
NONLINEAR FREQUENCY-CONVERSION
DOUBLE-LAMBDA SYSTEM
LASER-PULSES
MEDIA
PROPAGATION
STORAGE
Аннотация: We describe how to control the temporal shape of adiabaton using peculiarities of propagation dynamics under coherent population trapping. Temporal compression is demonstrated as a special case of pulse shaping. The general case of unequal oscillator strengths of two optical transitions in an atom is considered.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Effective refractive index of a two-dimensional polycrystal
Место публикации : JETP Letters. - 2015. - Vol. 101, Is. 10. - P.685-689. - ISSN 0021-3640, DOI 10.1134/S0021364015100033
Примечания : Cited References: 28
Предметные рубрики: SPECTROSCOPIC ELLIPSOMETRY
CONJUGATED POLYMERS
LOCAL-FIELD
FILMS
CONDUCTIVITY
POLYFLUORENE
ANISOTROPY
DISPERSION
MEDIA
Аннотация: A relation of the effective refractive index of a two-dimensional polycrystalline dielectric film in the transparency region to the refractive indices n1 and n2 of crystallites at the positions of axes 1 and 2, respectively, of refraction ellipsoids of the crystallites in the plane of the film has been obtained. This relation and the relation L* = (L1 + L2)/2 between the components of the Lorentz tensors for the film and crystallites have been confirmed by comparison with experimental data for conjugate-polymer films with uniaxial domains.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Tsikalov D. S.
Заглавие : Green's functions of the scalar model of electromagnetic fields in sinusoidal superlattices
Место публикации : Physica B: Elsevier, 2016. - Vol. 485. - P.94-102. - ISSN 09214526 (ISSN), DOI 10.1016/j.physb.2016.01.006
Примечания : Cited References: 30
Предметные рубрики: SCATTERING
MEDIA
PROPAGATION
GRATINGS
DENSITY
LIGHT
Ключевые слова (''Своб.индексиров.''): green's functions--electromagnetic waves--scalar model--sinusoidal superlattices--photonic crystals--ldos
Аннотация: Problems of obtaining Green's function and using it for studying the structure of scalar electromagnetic fields in a sinusoidal superlattice are considered. An analytical solution of equation in the k-space for Green's function is found. Green's function in the r-space is obtained by both the numerical and the approximate analytical Fourier transformation of that solution. It is shown, that from the experimental study of Green's function in the k-space the position of the plane radiation source relative to the extremes of the dielectric permittivity ?(z) can be determined. The relief map of Green's function in the r-space shows that the structure of the field takes the form of chains of islets in the plane ?z, the number of which increases with increasing the distance from a radiation source. This effect leads to different frequency dependences of Green's function at different distances from the radiation source and can be used to measure the distance to the internal source. The real component of Green's function and its spatial decay in the forbidden zones in the near field is investigated. The local density of states, depending on the position of the source in the superlattice, is calculated.
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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., Mankov Y. I.
Заглавие : Partial restoration of the wave spectrum of a superlattice due to cross correlations between one- and three-dimensional inhomogeneities
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2007. - Vol. 75, Is. 23. - Ст.235422. - ISSN 1098-0121, DOI 10.1103/PhysRevB.75.235422
Примечания : Cited References: 32
Предметные рубрики: ELASTIC MEDIUM THEORY
PERIODIC MULTILAYERS
SPIN-WAVES
LOCALIZATION
SYSTEMS
SUSCEPTIBILITY
DISORDER
MEDIA
Аннотация: Effects of cross correlations between one-dimensional (1D) and three-dimensional (3D) random inhomogeneities on the wave spectrum in sinusoidal superlattices are studied theoretically. The situation when the gap in the spectrum (the forbidden zone) at the first Brillouin zone boundary of the superlattice is closed under the action of the 1D inhomogeneities is considered. The phenomenon of the partial opening of this gap is found when the 3D inhomogeneities cross correlated with the 1D inhomogeneities add to the superlattice. The appearance of the logarithmic resonance in the center of the forbidden zone under the action of the cross correlations is shown. The physical nature of the effects in the wave spectrum of the superlattice that are caused by the cross correlations and the relation of these effects with the asymptotic properties of the correlation function of inhomogeneities are discussed.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Komogortsev S. V., Iskhakov R. S.
Заглавие : Magnetization curve and magnetic correlations in a nanochain of ferromagnetic grains with random anisotropy
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 3. - P495-501. - ISSN 1063-7834, DOI 10.1134/1.1884711
Примечания : Cited References: 31
Предметные рубрики: NANOCRYSTALLINE FERROMAGNETS
AMORPHOUS FERROMAGNETS
FIELD
MODEL
MICROSTRUCTURE
SIMULATIONS
DEPENDENCE
SYMMETRY
SYSTEM
MEDIA
Аннотация: The magnetization curve and magnetization correlation function are calculated for a ferromagnetic chain of single-domain nanoparticles with a randomly oriented anisotropy axis for different ratios between the exchange correlation and anisotropy energies. It is shown that the coercive force decreases as the exchange correlations increase. For strong exchange correlations, the magnetization curve is described by the following three successive magnetization processes as the applied field is increased: (i) nonuniform rotation of the magnetization of stochastic domains, (ii) collapse of the magnetic solitons, and (iii) nonuniform rotation of exchange-correlated magnetization vectors of the nanoparticles. For high fields, the calculated correlation function of the transverse magnetization components coincides with that predicted from linear theory. At low and zero fields, the main parameters of the correlation function (the variance and correlation radius) tend to certain finite values rather than diverge (as is the case in linear theory). The irreversible variation in the magnetization at low fields (the hysteresis loop) and the hysteresis of the main parameters of the correlation function are calculated. (c) 2005 Pleiades Publishing, Inc.
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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) : 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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16.

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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17.

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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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 : Wave spectrum of multilayers with finite thicknesses of interfaces
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2000. - Vol. 62, Is. 3. - P2181-2184. - ISSN 0163-1829, DOI 10.1103/PhysRevB.62.2181
Примечания : Cited References: 24
Предметные рубрики: SPIN
EXCITATIONS
MEDIA
Аннотация: To describe a 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. Depending on the value of the modulus kappa of the elliptic function, the model describes the limiting cases of multilayers with sharp interfaces (kappa=1, d/l=0, where d is the thickness of the interface, l is the period of the superlattice) and of sinusoidal superlattices (kappa=0, d/l=1/4), as Well as all intermediate situations. We investigate the wave spectrum in such a superlattice. The dependences of the widths of the gaps in the spectrum at the boundaries of ail odd Brillouin zones on the ratio d/l are found. It is shown that the thicknesses of the interfaces can be determined if the experimental value of the relation between the widths of the first gap Delta v(1) and any other gap Delta v(n) is known.
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20.

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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