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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Magnetoelastic resonance in media with the inhomogeneous coupling parameter
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: S. G. Ovchinnikov, A. Samardak: Trans Tech Publications, 2014. - Vol. 215: Trends in Magnetism: Nanomagnetism (EASTMAG-2013). - P.105-108. - DOI 10.4028/www.scientific.net/SSP.215.105. - ISSN 1662-9779
Примечания : Cited References: 8
Ключевые слова (''Своб.индексиров.''): elastic waves--green's functions--inhomogeneities--magnetoelastic coupling--self-consistent approximation--spin waves
Аннотация: The matrix Green's function of coupled spin and elastic waves for media with the 3D inhomogeneities of the coupling parameter is studied. It has been shown that the difference in shapes of the Green's functions for the cases of 1D and 3D inhomogeneities appears only for the sufficiently large correlation wave number of the inhomogeneities. © (2014) Trans Tech Publications, Switzerland.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Ospishchev S. V., Aleksandrov K. S.
Заглавие : Transport properties of HTSC plus Ba(Pb, Met)O-3 composites as functions of the electrical and magnetic characteristics of nonsuperconducting components
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 5. - P.810-815. - ISSN 1063-7834, DOI 10.1134/1.1131294
Примечания : Cited References: 27
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
CURRENT-VOLTAGE CHARACTERISTICS
NORMAL-METAL LAYER
WEAK LINKS
JUNCTIONS
SCATTERING
BAPB1-XBIXO3
TRANSITION
IMPURITIES
BREAKING
Аннотация: Composites simulating a network of weak metallic links and consisting of a classic 1-2-3 HTSC and a BaPbO3 metal oxide with incorporated Sn, Ni, and Fe impurities have been prepared. Experimental resistivity, magnetic, and Mossbauer studies of the BaPb(0.9)Met(0.1)O(3) nonsuperconducting components are presented. The transport properties of the HTSC + BaPb(0.9)Met(0.1)O(3) composites have been investigated. The superconducting properties of the composites are observed to be suppressed, both when the carrier mean free path in nonsuperconducting components with tin impurities decreases, and as a result of an additional interaction of the magnetic moments of (Fe, Ni) impurities with the spins of supercurrent carriers. The experimental temperature dependences of the composite critical current are analyzed in terms of the de Gennes theory for the superconductor-normal metal-superconductor structures. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sorokin B. P., Marushyak A. N., Aleksandrov K. S.
Заглавие : Influence of non-homogeneous uniaxial pressure on the propagation of bulk acoustic waves in crystals
Коллективы : IEEE Annual frequency control symposium
Место публикации : Proc Annu IEEE Int Freq Control Symp. - 2000. - P.404-409. - ISBN 0161-6404
Ключевые слова (''Своб.индексиров.''): acoustic bulk wave devices--calculations--crystal defects--crystal symmetry--functions--pressure effects--tensors--cubic crystal--green-christoffel equation--uniaxial mechanical pressure--acoustic wave propagation
Аннотация: The development of the theory of propagation small amplitude bulk acoustic waves in crystals under the uniaxial mechanical pressure has made by taking into account the condition of non-homogeneous deformation of crystal sample. It has been shown that the path of bulk acoustic waves will be function of a kind non-homogeneous deformation. As an example the calculation for some crystal directions of cubic crystal Bi12GeO20 (23 point symmetry) has made.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lundin A. A., Zobov V. E.
Заглавие : Order dependence of the profile of the intensities of multiple-quantum coherences
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 120, Is. 5. - P.762-771. - ISSN 1063, DOI 10.1134/S1063776115040093. - ISSN 10906509(eISSN)
Примечания : Cited References:62
Предметные рубрики: PARAMAGNETIC SPIN SYSTEMS
FREE-INDUCTION DECAY
NMR-SPECTRA
AUTOCORRELATION FUNCTIONS
FLUCTUATION SPECTRUM
TEMPERATURE DYNAMICS
LINE-SHAPE
SOLIDS
IRREVERSIBILITY
BEHAVIOR
Аннотация: A modification of the widespread phenomenological model theory of multiple-quantum (MQ) nuclear magnetic resonance spectra of a single cluster of correlated spins has been developed. In contrast to the mentioned theory, the size distribution of such clusters has been consistently taken into account. To obtain the distribution, solutions for the amplitudes of the expansion in the complete set of orthogonal operators are used. Expressions specifying the dependence of the profile of the intensities of MQ coherences on their number n (order) have been obtained. The total form of the dependence has been evaluated by means of the numerical implementation of the resulting expressions. The asymptotic expressions for large n values (wings of the spectrum) have been obtained analytically by the saddle-point method. It has been shown that the dependence under study has a Gaussian central part and exponential wings. The results obtained are in agreement with the previous calculations for some model systems and existing experimental data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Green’s function of magnetoelastic waves
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: N. Perov, A. Semisalova: Trans Tech Publications Ltd, 2015. - Vol. 233-234: Achievements in Magnetism. - P.12-15. - ISSN 1662-9779, DOI 10.4028/www.scientific.net/SSP.233-234.12. - ISSN 978-3-03835-482-6
Ключевые слова (''Своб.индексиров.''): dispersion relations--elastic waves--green’s functions--magnetoelastic coupling--resonances--spin waves--green's function--resonance--spin waves--wave propagation--approximate expressions--dipole dipole interactions--dispersion relations--elastic oscillations--longitudinal elastic wave--magnetoelastic couplings--off-diagonal elements--s function--elastic waves
Аннотация: The matrix (5x5) Green's function of magnetoelastic waves in an isotropic magnetoelastic medium taking into account the dipole-dipole interaction has been derived. The imaginary parts of diagonal and off-diagonal elements of the Green's function in the crossing resonance of spin and longitudinal elastic waves has been investigated. It is shown that under changing the angle of wave propagation θ the amplitudes of Green functions change drastically due redistribution of energy between the magnetic and elastic oscillation. Approximate expressions for the dependence of the widths of the gaps in the spectrum on the angle θ have been also derived. © (2015) Trans Tech Publications, Switzerland.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Tsikalov D. S.
Заглавие : Green’s functions of spin and electromagnetic waves in the sinusoidal superlattice
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Solid State Phenom.: Selected, peer reviewed papers/ ed.: N. Perov, A. Semisalova: Trans Tech Publications Ltd, 2015. - Vol. 233-234: Achievements in Magnetism. - P.47-50. - ISSN 1662-9779, DOI 10.4028/www.scientific.net/SSP.233-234.47. - ISSN 978-3-03835-482-6
Ключевые слова (''Своб.индексиров.''): continued fractions--electromagnetic waves--green’s functions--magnonic crystals--photonic crystals--sinusoidal modulation--spin waves--superlattices--circular waveguides--fourier transforms--green's function--photonic crystals--spin waves--superlattices--analytical expressions--continued fraction--fourier transformations--magnonic crystals--s function--sinusoidal modulation--spectral representations--electromagnetic waves
Аннотация: The problem of finding the Green's function of spin and electromagnetic waves in the sinusoidal superlattice is considered. An analytical expression for the spectral representation of the Green's function has been found in the form of ascending continued fractions, the particular denominators of which are ordinary continued fractions. The Green’s function in the r -space has been found by the numerical Fourier transformation of the Greens’s function found in the spectral representation. © (2015) Trans Tech Publications, Switzerland.
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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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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Woelfle P.
Заглавие : Manifestation of the upper Hubbard band in the 2D Hubbard model at low electron density
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 9-10. - P.834-839. - ISSN 1063-777X, DOI 10.1063/1.3670026; \b Физика низких температур
Примечания : Cited References: 31. - This work was supported by RFBR Grants No. 11-0200798 and 11-02-00741.
Предметные рубрики: 2-DIMENSIONAL FERMI GAS
LIQUID BEHAVIOR
SPECTRAL FUNCTIONS
TRANSITION METALS
SUPERCONDUCTIVITY
FERROMAGNETISM
DIMENSIONS
SCATTERING
STATE
Ключевые слова (''Своб.индексиров.''): electron density--electronic density of states--fermi liquid--green's function methods--hubbard model
Аннотация: We consider the 2D Hubbard model in the strong-coupling case (U W) and at low electron density (nd(2) ≪1). We find an antibound state as a pole in the two-particle T-matrix. The contribution of this pole in the self-energy reproduces a two-pole structure in the dressed one-particle Green-function similar to the Hubbard-I approximation. We also discuss briefly the Engelbrecht-Randeria mode which corresponds to the pairing of two holes below the bottom of the band for U W and low electron density. Both poles produce nontrivial corrections to Landau Fermi-liquid picture already at low electron density but do not destroy it in 2D.
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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) : Rubab N., Erkaev N. V., Langmayr D., Biernat H. K.
Заглавие : Kinetic Alfven wave instability in a Lorentzian dusty magnetoplasma
Коллективы :
Разночтения заглавия :авие SCOPUS: Kinetic Alfv́n wave instability in a Lorentzian dusty magnetoplasma
Место публикации : Phys. Plasmas: AMER INST PHYSICS, 2010. - Vol. 17, Is. 10. - Ст.103704. - ISSN 1070-664X, DOI 10.1063/1.3491336
Примечания : Cited References: 54. - This work is funded by the Higher Education Commission of Pakistan under the HEC-Overseas scholarship program Grant No. Ref: 1-1/PM OS /Phase-II/Batch-I/Austria/2007/. Part of this work was done while N. V. Erkaev was at the Space Research Institute of the Austrian Academy of Sciences in Graz. This work is also supported due to the RFBR Grant No. 09-05-91000-ANF-a. Further support is due to the "Austrian Fonds zur Forderung der Wissenschaftlichen Forschung" under Grant No. P20145-N16.
Предметные рубрики: MAXWELLIAN DISTRIBUTION-FUNCTIONS
FREQUENCY ELECTROMAGNETIC-WAVES
SOLAR-WIND
CHARGE FLUCTUATION
2-STREAM INSTABILITIES
ELECTROSTATIC MODES
SPACE PLASMAS
ION PLASMA
TEMPERATURE
PROPAGATION
Ключевые слова (''Своб.индексиров.''): analytical expressions--dispersion relations--distributed streaming--dust acoustic--dust particle--growth rate of instabilities--magnetized electrons--n-waves--potential theory--slow motion--streaming velocity--theoretical approach--two stream instability--whistler waves--dust--magnetic field effects--plasma waves--stability--acoustic wave propagation
Аннотация: This study presents a theoretical approach to analyze the influence of kappa distributed streaming ions and magnetized electrons on the plasma wave propagation in the presence of dust by employing two-potential theory. In particular, analytical expressions under certain conditions are derived for various modes of propagation comprising of kinetic Alfven wave streaming instability, two stream instability, and dust acoustic and whistler waves. A dispersion relation for kinetic Alfven-like streaming instability has been derived. The effects of dust particles and Lorentzian index on the growth rates and the threshold streaming velocity for the excitation of the instability are examined. The streaming velocity is observed to be destabilizing for slow motion and stabilizing for fast streaming motions. It is also observed that the presence of magnetic field and superthermal particles hinders the growth rate of instability. Possible applications to various space and astrophysical situations are discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3491336]
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12.

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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Berggren K. F., Maksimov D. N., Sadreev A. F., Hohmann R., Kuhl U., Stockmann H. J.
Заглавие : Quantum stress in chaotic billiards
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2008. - Vol. 77, Is. 6. - Ст.66209. - ISSN 1539-3755, DOI 10.1103/PhysRevE.77.066209
Примечания : Cited References: 43
Предметные рубрики: MICROWAVE CAVITIES
WAVE-FUNCTIONS
STATISTICAL PROPERTIES
SYSTEMS
FIELDS
Ключевые слова (''Своб.индексиров.''): computer networks--electric fields--electroacupuncture--electromagnetic field theory--electromagnetic fields--electromagnetism--function evaluation--functions--gaussian distribution--image segmentation--magnetism--mathematical models--microwaves--modal analysis--nematic liquid crystals--numerical analysis--random processes--stresses--tensors--trellis codes--two dimensional--wave functions--waves--abiotic and biotic stress--e ,2e theory--p ,p ,t measurements--american physical society (aps)--analytic expressions--current flowing--dinger equation--experimental studies--gaussian random fields--net flows--plane waves--quantum billiards--quantum-mechanical (qm)--scattering wave functions--sinai billiard (sb)--statistical distributions--stress tensors--two-dimensional (2d)--chaotic systems
Аннотация: This paper reports on a joint theoretical and experimental study of the Pauli quantum-mechanical stress tensor T(alpha beta)(x,y) for open two-dimensional chaotic billiards. In the case of a finite current flow through the system the interior wave function is expressed as psi=u + iv. With the assumption that u and v are Gaussian random fields we derive analytic expressions for the statistical distributions for the quantum stress tensor components T(alpha beta). The Gaussian random field model is tested for a Sinai billiard with two opposite leads by analyzing the scattering wave functions obtained numerically from the corresponding Schrodinger equation. Two-dimensional quantum billiards may be emulated from planar microwave analogs. Hence we report on microwave measurements for an open two-dimensional cavity and how the quantum stress tensor analog is extracted from the recorded electric field. The agreement with the theoretical predictions for the distributions for T(alpha beta)(x,y) is quite satisfactory for small net currents. However, a distinct difference between experiments and theory is observed at higher net flow, which could be explained using a Gaussian random field, where the net current was taken into account by an additional plane wave with a preferential direction and amplitude.
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14.

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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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I., Shorikov A., Anisimov V. I., Renner M., Brenig W.
Заглавие : Itinerant in-plane magnetic fluctuations and many-body correlations in NaxCoO2
Разночтения заглавия :авие SCOPUS: Itinerant in-plane magnetic fluctuations and many-body correlations in Nax Co O2
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2007. - Vol. 75, Is. 9. - Ст.94511. - ISSN 1098-0121, DOI 10.1103/PhysRevB.75.094511
Примечания : Cited References: 47
Предметные рубрики: TRANSITION-METALS
WAVE-FUNCTIONS
HUBBARD-MODEL
FERMI-SURFACE
ENERGY-BANDS
FERROMAGNETISM
APPROXIMATION
DIMENSIONS
SYSTEMS
FIELD
Аннотация: Based on the ab initio band structure for NaxCoO2, we derive the single-electron energies and the effective tight-binding description for the t(2g) bands using projection procedure. Due to the presence of the next-nearest-neighbor hoppings, a local minimum in the electronic dispersion close to the Gamma point of the first Brillouin zone forms. Correspondingly, in addition to a large Fermi surface, an electron pocket close to the Gamma point emerges at high doping concentrations. The latter yields a scattering channel, resulting in a peak structure of the itinerant magnetic susceptibility at small momenta. This indicates dominant itinerant in-plane ferromagnetic fluctuations above a certain critical concentration x(m), in agreement with neutron scattering data. Below x(m), the magnetic susceptibility shows a tendency toward the antiferromagnetic fluctuations. We further analyze the many-body effects on the electronic and magnetic excitations using various approximations applicable for different U/t ratios.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorban A., Popova T., Zinovyev A.
Заглавие : Codon usage trajectories and 7-cluster structure of 143 complete bacterial genornic sequences
Разночтения заглавия :авие SCOPUS: Codon usage trajectories and 7-cluster structure of 143 complete bacterial genomic sequences
Место публикации : Physica A: ELSEVIER SCIENCE BV, 2005. - Vol. 353. - P365-387. - ISSN 0378-4371, DOI 10.1016/j.physa.2005.01.043
Примечания : Cited References: 46
Предметные рубрики: DNA-BASE COMPOSITION
ASYMMETRIC SUBSTITUTION PATTERNS
PROTEIN-CODING REGIONS
MICROBIAL GENOMES
GENE IDENTIFICATION
MARKOV-MODELS
G+C CONTENT
BIAS
PREDICTION
SELECTION
Ключевые слова (''Своб.индексиров.''): genome--cluster--codon usage--correlations--entropy--mean field--cluster--codon usage--correlations--entropy--genome--mean field--approximation theory--correlation methods--database systems--entropy--functions--genes--mathematical models--clusters--codon usage--genomes--mean field--bacteria
Аннотация: Three results are presented. First, we prove the existence of a universal 7-cluster structure in all 143 completely sequenced bacterial genomes available in Genbank in August 2004, and explained its properties. The 7-cluster structure is responsible for the main part of sequence heterogeneity in bacterial genomes. In this sense, our 7 clusters is the basic model of bacterial genome sequence. We demonstrated that there are four basic "pure" types of this model, observed in nature: "parallel triangles", "perpendicular triangles", degenerated case and the flower-like type. Second, we answered the question: how big are the position-specific information and the contribution connected with correlations between nucleotide. The accuracy of the mean-field (context-free) approximation is estimated for bacterial genomes. We show that codon us-age of bacterial genomes is a multi-linear function of their genomic G+C-content with high accuracy (more precisely, by two similar functions, one for eubacterial genomes and the other one for archaea). Description of these two codon-usage trajectories is the third result. All 143 cluster animated 3D-scatters are collected in a database and is made available on our web-site: http://www.ihes.fr/similar to zinovyev/7clusters. (c) 2005 Elsevier B.V. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Maksimov D. N., Sadreev A. F.
Заглавие : Electric circuit networks equivalent to chaotic quantum billiards
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 4. - Ст.46205. - ISSN 1063-651X, DOI 10.1103/PhysRevE.71.046205
Примечания : Cited References: 31
Предметные рубрики: TIME-REVERSAL SYMMETRY
CONDUCTANCE FLUCTUATIONS
STATISTICS
SYSTEMS
EIGENFUNCTIONS
DOTS
Ключевые слова (''Своб.индексиров.''): chaotic quantum billiards--electric resonance circuits (erc)--resonance networks--wave functions--boundary conditions--capacitors--chaos theory--eigenvalues and eigenfunctions--electric inductors--natural frequencies--quantum theory--resonance--statistical mechanics--networks (circuits)
Аннотация: We consider two electric RLC resonance networks that are equivalent to quantum billiards. In a network of inductors grounded by capacitors, the eigenvalues of the quantum billiard correspond to the squared resonant frequencies. In a network of capacitors grounded by inductors, the eigenvalues of the billiard are given by the inverse of the squared resonant frequencies. In both cases, the local voltages play the role of the wave function of the quantum billiard. However, unlike for quantum billiards, there is a heat power because of the resistance of the inductors. In the equivalent chaotic billiards, we derive a distribution of the heat power which describes well the numerical statistics.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rotter I., Sadreev A. F.
Заглавие : Avoided level crossings, diabolic points, and branch points in the complex plane in an open double quantum dot
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 3. - Ст.36227. - ISSN 1063-651X, DOI 10.1103/PhysRevE.71.036227
Примечания : Cited References: 49
Предметные рубрики: BERRY TOPOLOGICAL PHASE
EXCEPTIONAL POINTS
GEOMETRIC PHASES
NUCLEAR REACTIONS
RESONANCE STATES
UNIFIED THEORY
S-MATRIX
CONTINUUM
REPULSION
INTERFEROMETER
Ключевые слова (''Своб.индексиров.''): branch points in the complex plane (bpcp)--diabolic points (dp)--geometric phases--riemann sheets--eigenvalues and eigenfunctions--electron energy levels--functions--hamiltonians--quantum theory--resonance--topology--semiconductor quantum dots
Аннотация: We study the spectrum of an open double quantum dot as a function of different system parameters in order to receive information on the geometric phases of branch points in the complex plane (BPCP). We relate them to the geometrical phases of the diabolic points (DPs) of the corresponding closed system. The double dot consists of two single dots and a wire connecting them. The two dots and the wire are represented by only a single state each. The spectroscopic values follow from the eigenvalues and eigenfunctions of the Hamiltonian describing the double dot system. They are real when the system is closed, and complex when the system is opened by attaching leads to it. The discrete states as well as the narrow resonance states avoid crossing. The DPs are points within the avoided level crossing scenario of discrete states. At the BPCP, width bifurcation occurs. Here, different Riemann sheets evolve and the levels do not cross anymore. The BPCP are physically meaningful. The DPs are unfolded into two BPCP with different chirality when the system is opened. The geometric phase that arises by encircling the DP in the real plane, is different from the phase that appears by encircling the BPCP. This is found to be true even for a weakly opened system and the two BPCP into which the DP is unfolded.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : The coordinate of a singular point of the time correlation functions for a heteronuclear spin system of a crystal
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 4. - P775-783. - ISSN 1063-7761, DOI 10.1134/1.1926438
Примечания : Cited References: 24
Предметные рубрики: FLUCTUATION SPECTRUM
CROSS-RELAXATION
NMR ABSORPTION
SHAPE
WINGS
LINE
Ключевые слова (''Своб.индексиров.''): correlation methods--crystal lattices--crystallography--functions--integral equations--lithium compounds--nuclear magnetic resonance--quantum theory--random processes--autocorrelation functions (acf)--dipole-dipole interactions (ddi)--heteronuclear spin systems--self-consistent fluctuating field (scff)--crystals
Аннотация: The singularities of the time autocorrelation functions (ACFs) for a heteronuclear spin system of a crystal are investigated. Exact expressions are obtained for ten moments of the spectra of ACFs in the approximation of a self-consistent fluctuating field (SCFF) with arbitrary axial symmetry. These expressions are applied to determine the coordinate of the lowest singular point of these functions on the imaginary-time axis for a spin system with a dipole-dipole interaction (DDI). The leading corrections to this coordinate due to the correlation of local fields in real crystals are calculated. These corrections are determined by lattice sums with triangles of four bonds and pairs of four bonds. Numerical values of the coordinate are obtained for a LiF crystal in a magnetic field directed along three crystallographic axes. An increase in the coordinate of the singular point, which follows from the theory and leads to a faster falloff of the wings of the ACF spectra, qualitatively agrees with experiment. © 2005 Pleiades Publishing, Inc.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Statistics of wave functions and currents induced by spin-orbit interaction in chaotic billiards
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2004. - Vol. 70, Is. 5. - Ст.56211. - ISSN 1539-3755, DOI 10.1103/PhysRevE.70.056211
Примечания : Cited References: 33
Предметные рубрики: HELMHOLTZ-EQUATION
PERSISTENT CURRENTS
ELECTRON-GAS
RINGS
EIGENFUNCTIONS
SYSTEMS
PHASE
Ключевые слова (''Своб.индексиров.''): approximation theory--chaos theory--degrees of freedom (mechanics)--eigenvalues and eigenfunctions--electric field effects--electric potential--electron gas--hamiltonians--heterojunctions--microwaves--statistical methods--chaotic robnik billiards--current distributions--spin-orbit interaction (soi)--wave functions--quantum theory
Аннотация: We show that the wave function and current statistics in chaotic Robnik billiards crucially depend on the constant of the spin-orbit interaction (SOI). For small constant the current statistics is described by universal current distributions derived for slightly opened chaotic billiards [Saichev et al. J. Phys. A. 35, L87 (2002)] although one of the components of the spinor eigenfunctions is not universal. For strong SOI both components of the spinor eigenstate are complex random Gaussian fields. This observation allows us to derive the distributions of spin-orbit persistent cut-rents which well describe numerical statistics. For intermediate values of the statistics of the eigenstates and currents, both are deeply nonuniversal.
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