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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Atomic current in optical lattices: Reexamination of the Esaki-Tsu equation
Место публикации : Phys. Rev. A. - COLLEGE PK: AMER PHYSICAL SOC, 2008. - Vol. 77, Is. 6. - С. 063604. - JUN. - ISSN 1050-2947, DOI 10.1103/PhysRevA.77.063604
Примечания : Cited Reference Count: 13
Ключевые слова (''Своб.индексиров.''): atomic physics--atoms--crystal lattices--optical materials--standards--systems analysis--velocity control--american physical society (aps)--drift currents--master equations--optical lattices (ol)--standard form--velocity distribution
Аннотация: This paper discusses the master equation approach to the derivation of the Esaki-Tsu equation for drift current. It is shown that the relaxation term in the master equation can be identified by measuring the velocity distribution of the carriers. We also show that the standard form of the relaxation term, used earlier to derive the Esaki-Tsu equation, predicts unphysical velocity distribution. We suggest a more elaborate relaxation term, which is argued to correctly capture the effect of a bosonic bath in experiments on atomic current in optical lattices.
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2.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aleksandrov K. S., Turchin P. P., Sorokin B. P., Karpovich A. A., Nefedov V. A.
Заглавие : Bulk acoustic waves propagation in Li2B4O7 piezoelectric crystals under the static uniaxial mechanical pressure
Коллективы : Annual frequency control symposium
Место публикации : Proceedings of the Annual IEEE International Frequency Control Symposium/ Annual frequency control symposium (54 ; 2000 ; Jun. ; 7-9 ; Kansas, MO). - 2000. - P.214-217. - ISBN 01616404
Примечания : Cited References: 8
Ключевые слова (''Своб.индексиров.''): acoustic wave transmission--acoustic wave velocity--elasticity--lithium compounds--mathematical models--permittivity--piezoelectricity--pressure effects--single crystals--electromechanical constants--piezoelectric crystal--piezoelectric materials
Аннотация: The influence of uniaxial mechanical stresses on bulk acoustic waves velocity in piezoelectric crystals Li2B4O7 has been investigated. Electromechanical constants have determined.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseev K. N., Berman G. P., Campbell D. K., Cannon E. H., Cargo M. C.
Заглавие : Dissipative chaos in semiconductor superlattices
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1996. - Vol. 54, Is. 15. - P10625-10636. - ISSN 0163-1829, DOI 10.1103/PhysRevB.54.10625
Примечания : Cited References: 89
Предметные рубрики: NEGATIVE DIFFERENTIAL CONDUCTIVITY
INJECTED SIGNAL
BLOCH OSCILLATIONS
COLLECTIVE EXCITATIONS
DETERMINISTIC CHAOS
MINIBAND TRANSPORT
SURFACE-PLASMONS
TIME-SERIES
LASER
VELOCITY
Аннотация: We consider the motion of ballistic electrons in a miniband of a semiconductor superlattice (SSL) under the influence of an external, time-periodic electric field. We use a semiclassical, balance-equation approach, which incorporates elastic and inelastic scattering (as dissipation) and the self-consistent field generated by the electron motion. The coupling of electrons in the miniband to the self-consistent held produces a cooperative nonlinear oscillatory mode which, when interacting with the oscillatory external field and the intrinsic Bloch-type oscillatory mode, can lead to complicated dynamics, including dissipative chaos. For a range of values of the dissipation parameters we determine the regions in the amplitude-frequency plane of the external field in which chaos can occur. Our results suggest that for terahertz external fields of the amplitudes achieved by present-day free-electron lasers, chaos may be observable in SSL's. We clarify the nature of this interesting nonlinear dynamics in the superlattice-external-field system by exploring analogies to the Dicke model of an ensemble of two-level atoms coupled with a resonant cavity field, and to Josephson junctions.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : Effect of degradation processes caused by a small perturbation on the growth of the average cluster size of correlated spins in multiple quantum NMR spectroscopy of solids
Место публикации : Appl. Magn. Reson. - 2021. - Vol. 52. Is. 7. - P.879–892. - ISSN 09379347 (ISSN), DOI 10.1007/s00723-021-01342-1
Примечания : Cited References: 33. - The study is funded by the Ministry of Science and Higher Education of the Russian Federation in the framework of the State assignment, State registration number AAAA-A19-119012890064-7
Аннотация: Multiple quantum (MQ) NMR spectroscopy of solids allows one to observe the growth and decay of multispin correlations. As a rule, the average size of the cluster of correlated spins is extracted from the width of the MQ spectrum. In the present article, the size distribution of such clusters is explored. To obtain the above distribution, the solutions for the amplitudes of the decomposition over complete sets of orthogonal operators for the two different models were used. By means of these models, we have taken into account the dependence of cluster degradation (the degradation of a cluster means, e.g., destruction of correlations in cluster or loss of particles in it) through two positions. The first one defines by the cluster size while the second one depends on the MQ coherence order of the cluster. It is shown that in dependence of the relation the rates of these degradation processes, the width of the MQ spectrum carries different information. If the first process is faster that the second one, then the width of the MQ spectrum is still determined by the average cluster size. When the velocity ratio becomes inverse, the width of the MQ spectrum takes on a smaller value, which is a consequence of the faster degradation of the MQ spectrum components with large orders of coherence.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mankov Y. I.
Заглавие : Electromagnetic waves with a negative group velocity in a randomly inhomogeneous Josephson junction
Место публикации : Phys. Solid State. - 2013. - Vol. 55, Is. 5. - P.924-929. - ISSN 1063-7834, DOI 10.1134/S1063783413050223
Аннотация: Electromagnetic waves in a randomly inhomogeneous Josephson junction have been investigated by the averaged Green's function method for a nonmonotonic decay of the correlations of inhomogeneities. Modifications of the spectrum and the decay of these excitations caused by spatial fluctuations of the critical current of the Josephson junction have been studied. The regions of the values of the frequency, the wave number, and the stochastic parameters of the medium, at which the waves have a negative group velocity, have been determined. В© 2013 Pleiades Publishing, Ltd.
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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sorokin B. P., Marushyak A. N., Aleksandrov K. S.
Заглавие : Influence of heterogeneous external fields on propagation of bulk acoustic waves in crystals
Коллективы : IEEE International ultrasonics symposium
Место публикации : Proceedings - IEEE Ultrasonics Symposium. - 2008. - Ст.4803313. - P.1472-1475. - ISBN 1051-0117, DOI 10.1109/ULTSYM.2008.0358
Ключевые слова (''Своб.индексиров.''): bulk elastic wave--non-homogeneous mechanical loading--phase velocity--wave surface--bulk acoustic waves--bulk elastic wave--bulk waves--external fields--non-homogeneous--non-homogeneous mechanical loading--numerical calculation--small amplitude--wave surface--acoustic fields--crystals--elastic waves--elasticity--phase velocity--silicon compounds--soil structure interactions--waves--velocity
Аннотация: Formulas describing the influence of nonhomogeneous pressure on propagation of bulk waves in crystals have derived. Phase velocity for small amplitude waves in Bi12SiO20 crystal the action of non-homogeneous pressure has been . Under those conditions the behavior of the wave has researched. Numerical calculation of phase velocity of and their directions propagation changing have obtained. В©2008 IEEE.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Avramov P. V., Ovchinnikov S. G., Kresse G.
Заглавие : Isotope velocity differentiation in thin carbon nanotubes through quantum diffusion
Место публикации : Europhys. Lett. - 2003. - Vol. 63, Is. 2. - P.254-260. - ISSN 0295-5075, DOI 10.1209/epl/i2003-00512-5
Примечания : Cited References: 17
Предметные рубрики: MOLECULAR-DYNAMICS
TRANSITIONS
TRANSPORT
ENERGY
Аннотация: An approach is proposed to evaluate the average velocities of adsorbate molecules in one-dimensional nanopore, when quantum tunneling between neighboring potential minima leads to nonzero velocity. The approach is used to calculate the hydrogen isotope molecule (H-2, D-2, T-2) velocities in ultrathin carbon single-wall nanotubes (SWNT) (3, 3) and (6, 0). It is shown that the isotope mass difference leads to large differences of the quantum tunneling value and large differences of the average molecule velocities, especially inside the tube (6, 0). It is shown that different tube chirality leads to drastically different velocities of adsorbate molecules, even if the diameters of both nanotubes do not differ significantly.
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8.

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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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G.
Заглавие : LDA plus GTB (generalized tight-binding) method for the electronic structure calculations of strongly correlated electron systems: Application for the band structure calculations of p-type cuprates
Разночтения заглавия :авие SCOPUS: LDA + GTB (generalized tight-binding) method for the electronic structure calculations of strongly correlated electron systems: Application for the band structure calculations of p-type cuprates
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2007. - Vol. 460: 8th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (JUL 09-14, 2006, Dresden, GERMANY). - P1018-1019. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.03.381
Примечания : Cited References: 12
Предметные рубрики: 3-CENTER INTERACTIONS
MODEL
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--superconductivity--p-type cuprates--spin fluctuations--fermi surface--fermi surface--p-type cuprates--spin fluctuations--strongly correlated electron systems--superconductivity--band structure--correlation methods--electronic structure--fermi surface--hubbard model--mean field theory--spin fluctuations--superconductivity--fermi velocity--hole pockets--strongly correlated electron systems--oxide superconductors
Аннотация: Mean-field theory of the non-superconducting phase of the high-T-c cuprates is formulated within the effective t-t'-t"-J model with three-site correlated hoppings. This model with the ab initio calculated parameters results from the LDA + GTB method. The static spin and kinematical correlation functions beyond Hubbard I approximation are calculated self-consistently taking into account hoppings to the first, the second, and the third neighboring sites, as well as the three-site correlated hoppings. The obtained Fermi surface evolves from hole-pockets at low-doping to large hole-type Fermi surface at higher doping concentrations. Calculated doping dependence of the nodal Fermi velocity, the effective mass and the chemical potential shift are in good agreement with experimental data. (c) 2007 Elsevier B.V. All rights reserved.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Erkaev N. V., Semenov V. S., Biernat H. K.
Заглавие : Magnetic double-gradient instability and flapping waves in a current sheet
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2007. - Vol. 99, Is. 23. - Ст.235003. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.99.235003
Примечания : Cited References: 10
Предметные рубрики: MAGNETOTAIL CURRENT SHEET
CLUSTER
Ключевые слова (''Своб.индексиров.''): magnetic fields--magnetic properties--magnetohydrodynamics--velocity measurement--current sheets--flapping waves--magnetic gradients--stable regions--electromagnetic waves
Аннотация: A new kind of magnetohydrodynamic instability and waves are analyzed for a current sheet in the presence of a small normal magnetic field component varying along the sheet. These waves and instability are related to the existence of two gradients of the tangential (B(tau)) and normal (B(n)) magnetic field components along the normal (del(n)B(tau)) and tangential (del(tau)B(n)) directions with respect to the current sheet. The current sheet can be stable or unstable if the multiplication of two magnetic gradients is positive or negative. In the stable region, the kinklike wave mode is interpreted as so-called flapping waves observed in Earth's magnetotail current sheet. The kink wave group velocity estimated for the Earth's current sheet is of the order of a few tens of kilometers per second. This is in good agreement with the observations of the flapping motions of the magnetotail current sheet.
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