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1.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V.A., Tsikalov D.S.
Заглавие : Combined effects of 2D and 3D inhomogeneities on high-frequency susceptibility of superlattices
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Уральское отделение РАН
Место публикации : IV Euro-Asian Symposium "Trends in MAGnetism" Nanospintronics (EASTMAG-2010). School for young scientist "Spintronics": June 28 - Lule 2, 2010"Book of abstracts. - Ekaterinburg, 2010. - P.327
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2.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Tsikalov D. S.
Заглавие : Combined Effects of 2D and 3D Inhomogeneities on the Dynamic Susceptibility of Superlattices
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", Russian Acad Sci, Inst Metal Phys
Место публикации : TRENDS IN MAGNETISM. - STAFA-ZURICH: TRANS TECH PUBLICATIONS LTD, 2011. - Vol. 168-169. - С. 97-100. - (Solid State Phenomena). - ISBN 1012-0394, DOI 10.4028/www.scientific.net/SSP.168-169.97
Примечания : Cited Reference Count: 10
Предметные рубрики: Materials Science, Multidisciplinary
Physics, Condensed Matter
Ключевые слова (''Своб.индексиров.''): waves--superlattices--inhomogeneities--dynamic susceptibility--dos
Аннотация: The dynamic susceptibility and the one-dimensional density of states (DOS) of an initially sinusoidal superlattice (SL) with simultaneous presence of two-dimensional (2D) phase inhomogeneities that simulate the deformations of the interfaces between the SL's layers and three-dimensional (3D) amplitude inhomogeneities of the layer material of the SL were investigated. An analytical expression for the averaged Green's function of the sinusoidal SL with 2D phase inhomogeneities was obtained in the Bourret approximation. It was shown that the effect of increasing asymmetry of heights of the dynamic susceptibility peaks at the edge of the Brillouin zone of the SL, which was found in [6] at increasing the rms fluctuations of 2D inhomogeneities, also takes place at increasing the correlation wave number of such inhomogeneities. It was also shown that The increase of the tins fluctuations of 3D amplitude inhomogeneities in the superlattice with 2D phase inhomogeneities leads to the suppression of the asymmetry effect and to the decrease of the depth of the DOS gap.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deich L. I., Ignatchenko V. A.
Заглавие : Phonon spectroscopy of inhomogeneities in disordered solids
Разночтения заглавия :us: Phonon spectroscopy of inhomogeneties in disordered solids
Место публикации : Solid State Commun. - 1991. - Vol. 80, Is. 10. - P.881-884. - ISSN 0038-1098, DOI 10.1016/0038-1098(91)90525-Z
Примечания : Cited References: 15
Предметные рубрики: SPIN-WAVES
AMORPHOUS FILMS
DISPERSION
FERROMAGNETS
Аннотация: A possibility to use elastic waves for investigation of inhomogeneities corresponding in size to intermediate order in disordered solids is considered. It is shown that frequency dependencies of phase and group velocities of the elastic waves have some peculiarities which give the possibilities to find the characteristic size of inhomogenities and to determine the parameter of a matter whose fluctuations are most significant for the phenomena under study.
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4.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V.A.
Заглавие : Effects of correlated inhomogeneities of the spectral properties of disordered ferro magnets and superlattices
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Уральское отделение РАН
Место публикации : IV Euro-Asian Symposium "Trends in MAGnetism" Nanospintronics (EASTMAG-2010). School for young scientist "Spintronics": June 28 - Lule 2, 2010"Book of abstracts. - Ekaterinburg, 2010. - P.300 (Invited)
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effects of cross correlation between inhomogeneities of the exchange and anisotropy on the spin-wave spectrum
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2008): June 20-25, 2008, Moscow : book of abstract. - 2008. - Ст.23PO-12-12. - p.516-517
Примечания : This work was supported by the Grant of the RF President, SS-3818.2008.3
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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V.A.
Заглавие : Effects of cross correlation between inhomogeneities on the spectum and damping of spin and elastic waves (invited)
Коллективы : "Functional Materials", International Conference
Место публикации : International Conference "Functional Materials" (ICFM-09): book of abstracts : October 5-10, Ukraine, Crimea, Partenit. - 2009. - С. 281
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effects of cross correlations between inhomogeneities of the parameters of an isotropic medium on the spectrum and damping of elastic waves
Место публикации : J. Exp. Theor. Phys. - NEW YORK: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 2. - С. 345-359. - FEB. - ISSN 1063-7761, DOI 10.1134/S1063776110020184
Примечания : Cited Reference Count: 17. - Гранты: This study was supported in part by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools (grant no. 3818.2008.3) and the Presidium of the Russian Academy of Sciences (program no. 27.1) and performed within the framework of the Federal Target Program (State Contract no. 02.740.11.0220).Финансирующая организация: Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools [3818.2008.3]; Presidium of the Russian Academy of Sciences [27.1]; Federal Target Program [02.740.11.0220]
Ключевые слова (''Своб.индексиров.''): cross correlations--dispersion law--elastic force--inhomogeneities--isotropic medium--negative cross-correlation--physical nature--two parameter--wave spectra--damping--dispersions--elastic waves--hamiltonians--dispersion (waves)
Аннотация: The dispersion and damping laws have been investigated for elastic waves in an isotropic medium with one- and three-dimensional inhomogeneities of the density p(x) of the material and the elastic force constants mu(x) and lambda(x) with allowance for the cross correlations between these inhomogeneities. It has been demonstrated that the positive cross correlations between mu(x) and lambda(x), as well as the negative cross correlations between p(x) and mu(x) or p(x) and lambda(x), lead to an enhancement of the modification of the dispersion law and an increase in the damping of waves. The positive cross correlations between p(x) and mu(x) or p(x) and lambda(x), as well as the negative cross correlations between mu(x) and lambda(x), result in the opposite effects: a weakening of the modification of the dispersion law and a decrease in the damping. An analysis of the results obtained in this paper and in our recent work [15] has made it possible to formulate the general regularity of the effects of cross correlations, irrespective of the physical nature of the waves: the effects of cross correlations between inhomogeneities of any two parameters of the material on the wave spectrum depend on whether both parameters related by the cross correlations belong to the same part of the Hamiltonian (i.e., if they both belong to either the kinetic part or the potential part of the Hamiltonian) or they belong to different parts of the Hamiltonian. The positive cross correlations lead to a greater modification of the dispersion law and to an increase in the damping of waves in the former case and to a decrease in these characteristics in the latter case. Correspondingly, the negative cross correlations in each of these cases result in the opposite effects. This regularity has been explained qualitatively.
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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Yu. I.
Заглавие : Effects of inhomogeneities with extended correlations on the spin wave spectrum in nanocrystals and superlattices
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2008): June 20-25, 2008, Moscow : book of abstract. - 2008. - Ст.24TL-F-3. - p.581-582
Примечания : These works were supported by the Grant of the RF President, SS-3818.2008.3.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Stolyar S. V., Yakovchuk V. Yu., Chizhik M. V., Pozdnyakov V. G., Vazhenina I. G.
Заглавие : Ferromagnetic and spin-wave resonance in FexNi1-x (0x1) films
Место публикации : TRENDS IN MAGNETISM. - 2011. - Vol. 168-169. - С. 93-96. - ISSN 10120394 (ISSN); 9783037850213 (ISBN), DOI 10.4028/www.scientific.net/SSP.168-169.93
Ключевые слова (''Своб.индексиров.''): correlation radius--dispersion law for spin waves--exchange interaction--ferromagnetic resonance--spin-wave resonance--thermal evaporation method--crystal structure--dispersion (waves)--dispersions--evaporation--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--resonance--spin waves--crystal structure--dispersion (waves)--evaporation--exchange interactions--ferromagnetic materials--ferromagnetic resonance--ferromagnetism--multilayers--resonance--spin waves--thermal evaporation--bcc structure--correlation radius--dispersion law--feni alloys--magnetic inhomogeneities--magnetic state--magnetization fluctuations--spin-wave resonance--thermal evaporation method--spin wave resonances--thermal evaporation--magnetism
Аннотация: The spectrum of standing exchange magnon wave in FeNi alloy films obtained by thermal evaporation method is studied. The modification of dispersion law conditioned by magnetization fluctuations is detected. The films of invar structure having metastable bcc structure are most dispersing relative to magnetic state. The size of magnetic inhomogeneity was less than 5 nm.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chekanova L. A., Komogortsev S. V., Denisova E. A., Kuzovnikova L. A., Nemtsev I. V., Yaroslavtsev R. N., Iskhakov R. S.
Заглавие : Ferromagnetic resonance linewidth in powders consisting of core–shell particles
Место публикации : Bull. Russ. Acad. Sci. Phys.: Allerton Press Incorporation, 2017. - Vol. 81, Is. 3. - P.351-353. - ISSN 10628738 (ISSN), DOI 10.3103/S1062873817030091
Примечания : Cited References: 4
Ключевые слова (''Своб.индексиров.''): ferromagnetic resonance--ferromagnetism--linewidth--powders--resonance--shells (structures)--composite particles--demagnetizing field--ferromagnetic cores--ferromagnetic resonance linewidth--inhomogeneities--magnetic particle--non-ferromagnetic--nonmagnetics--ferromagnetic materials
Аннотация: The dependence of the ferromagnetic resonance linewidth on the thickness of nonmagnetic shells in powders consisting of ferromagnetic core–nonferromagnetic shell composite particles is investigated. It is found that an increase in shell thickness reduces the ferromagnetic resonance linewidth by several times, down to values comparable to those for coatings with compositions similar to that of the particle’s core. The observed effect is assumed to result from suppression of the inhomogeneity of demagnetizing fields in a powder consisting of magnetic particles. © 2017, Allerton Press, Inc.
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11.

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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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Yu. I., Tsikalov D. S.
Заглавие : High-frequency susceptibility of superlattices with two dimensional inhomogeneities
Коллективы : Moscow International Symposium on Magnetism, Московский государственный университет им. М.В. Ломоносова, Российский фонд фундаментальных исследований
Место публикации : Moscow Int. Symp. on Magnet. (MISM-2008): June 20-25, 2008, Moscow : book of abstract. - 2008. - Ст.21PO-16-16. - p.113-114
Примечания : This work was partially supported by the Grant of the RF President, SS – 3818.2008.3
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Development of a self-consistent approximation
Место публикации : J. Phys. A: IOP Publishing, 2016. - Vol. 49, Is. 9. - Ст.095004. - ISSN 17518113 (ISSN), DOI 10.1088/1751-8113/49/9/095004
Примечания : Cited References: 43
Предметные рубрики: SUPERCONDUCTING CRITICAL-TEMPERATURE
LATTICE-VIBRATIONS
VERTEX FUNCTION
ELECTRON
Ключевые слова (''Своб.индексиров.''): self-consistent approximation--green's functions--vertex corrections--inhomogeneities--correlations--dynamic susceptibility
Аннотация: A self-consistent approximation of a higher level than the standard self-consistent approximation, known in various fields of physics as the Migdal, Kraichnan or Born self-consistent approximation, is derived taking into account both the first and second terms of the series for the vertex function. In contrast to the standard approximation, the new self-consistent approximation is described by a system of two coupled nonlinear integral equations for the self-energy and the vertex function. In addition to all the diagrams with non-intersecting lines of correlation/interaction taken into account by the standard self-consistent approximation, the new approach takes into account in each term of the Green's function expansion a significant number of diagrams with intersections of these lines. Because of this, the shape, linewidth, and amplitude of the resonance peaks of the dynamic susceptibility calculated in this approximation are much closer to the exact values of these characteristics. The advantage of the new self-consistent approach is demonstrated by the example of calculation of the dynamic susceptibility of waves in an inhomogeneous medium. © 2016 IOP Publishing Ltd.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effect of cross correlations between inhomogeneities on the spectrum and damping of spin and elastic waves
Коллективы :
Место публикации : Low Temp. Phys. - 2010. - Vol. 36, Is. 8-9. - P.741-746. - ISSN 1063-777X, DOI 10.1063/1.3490860; \b Физика низких температур
Примечания : Cited References: 13. - This work was partially supported by Program No. 27 of the Presidium of the Russian Academy of Sciences, State contract No. 02.740.11.0220 as part of the Federal targeted program and the State program "Development of the scientific potential of higher education," project No. 2.1.1/3498.
Предметные рубрики: FERROMAGNET
Аннотация: This is a study of the dispersion relations and damping of spin waves in ferromagnets with inhomogeneities in their exchange and magnetic anisotropy parameters and of elastic waves in isotropic media with inhomogeneities in the density of matter and in the elastic force constants, with cross correlations between these inhomogeneities taken into account. A general behavior is found which is independent of the physical nature of the waves: the kind of effect cross correlations between inhomogeneities in any two parameters of a material will have on the wave spectrum depends on whether both parameters belong to the same (i.e., both belong to the kinetic part or both belong to the potential part) or to different parts of the hamiltonian. In the former case, positive cross correlations lead to a substantial modification of the dispersion relation and to increased wave damping, and in the latter case, to a smaller modification of these characteristics. On the other hand, negative cross correlations lead to the opposite effects in both cases. This behavior is explained qualitatively. (c) 2010 American Institute of Physics. [doi:10.1063/1.3490860]
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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) : 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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effects of cross correlations between exchange and magnetic-anisotropy inhomogeneities on the spectrum and damping of spin waves
Коллективы : Russian Federation for the Support of Leading Scientific Schools [3818.2008.3]
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 5. - P940-948. - ISSN 1063-7834, DOI 10.1134/S1063783409050096
Примечания : Cited References: 9. - This study was supported in part by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools (project no. 3818.2008.3).
Аннотация: Effects of cross correlations between inhomogeneities of the exchange and magnetic-anisotropy parameters on the spectrum and damping of spin waves in a ferromagnet are investigated. One- and three-dimensional inhomogeneities are considered. It is demonstrated that the positive cross correlations lead to an increase in the modification of the dispersion law and the damping of spin waves. The negative cross correlations result in the opposite effects: a decrease in the modification of the dispersion law and a decrease in the damping of spin waves. A comparison of the specific features revealed in this work and the results of targeted experimental investigations of modifications of the dispersion laws and damping in inhomogeneous magnets would make it possible to determine the contribution of the cross correlations to the formation of the stochastically inhomogeneous ground state in amorphous magnetic alloys.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effects of cross correlations between inhomogeneities of the parameters of an isotropic medium on the spectrum and damping of elastic waves
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 2. - P345-359. - ISSN 1063-7761, DOI 10.1134/S1063776110020184
Примечания : Cited References: 17. - This study was supported in part by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools (grant no. 3818.2008.3) and the Presidium of the Russian Academy of Sciences (program no. 27.1) and performed within the framework of the Federal Target Program (State Contract no. 02.740.11.0220).
Ключевые слова (''Своб.индексиров.''): cross correlations--dispersion law--elastic force--inhomogeneities--isotropic medium--negative cross-correlation--physical nature--two parameter--wave spectra--damping--dispersions--elastic waves--hamiltonians--dispersion (waves)
Аннотация: The dispersion and damping laws have been investigated for elastic waves in an isotropic medium with one- and three-dimensional inhomogeneities of the density p(x) of the material and the elastic force constants mu(x) and lambda(x) with allowance for the cross correlations between these inhomogeneities. It has been demonstrated that the positive cross correlations between mu(x) and lambda(x), as well as the negative cross correlations between p(x) and mu(x) or p(x) and lambda(x), lead to an enhancement of the modification of the dispersion law and an increase in the damping of waves. The positive cross correlations between p(x) and mu(x) or p(x) and lambda(x), as well as the negative cross correlations between mu(x) and lambda(x), result in the opposite effects: a weakening of the modification of the dispersion law and a decrease in the damping. An analysis of the results obtained in this paper and in our recent work [15] has made it possible to formulate the general regularity of the effects of cross correlations, irrespective of the physical nature of the waves: the effects of cross correlations between inhomogeneities of any two parameters of the material on the wave spectrum depend on whether both parameters related by the cross correlations belong to the same part of the Hamiltonian (i.e., if they both belong to either the kinetic part or the potential part of the Hamiltonian) or they belong to different parts of the Hamiltonian. The positive cross correlations lead to a greater modification of the dispersion law and to an increase in the damping of waves in the former case and to a decrease in these characteristics in the latter case. Correspondingly, the negative cross correlations in each of these cases result in the opposite effects. This regularity has been explained qualitatively.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Felk V. A.
Заглавие : Effects of long-wave inhomogeneities of the exchange and elastic force constants in the framework of the coherent potential approximation
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2006. - Vol. 74, Is. 17. - Ст.174415. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.174415
Примечания : Cited References: 14
Предметные рубрики: CRYSTALS
MODEL
Аннотация: The formalism of averaged Green's functions in the continuum is developed for spin waves in ferromagnets with inhomogeneities of the exchange constant and elastic waves in media with inhomogeneities of the force constant. The integral self-consisted equation in the coherent potential approximation is developed for taking into account effects of inhomogeneities of these nonlocal characteristics of the material on the wave spectrum in it. The obtained general results are applied to the study of effects of one-dimensional inhomogeneities of the exchange constant on the wave spectrum in a ferromagnet.
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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 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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