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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R., Bulgakov E. N.
Заглавие : Wannier-Stark states and Bloch oscillations in the honeycomb lattice
Место публикации : Phys. Rev. B. - 2013. - Vol. 87, Is. 3. - Ст.033602. - P. - ISSN 1050-2947, DOI 10.1103/PhysRevA.87.033602
Ключевые слова (''Своб.индексиров.''): bloch oscillations--chaotic state--honeycomb lattices--localization length--localized state--quantum particles--static fields--tight-binding approximations--solid state physics--honeycomb structures
Аннотация: We study a quantum particle in a tilted honeycomb lattice in the tight-binding approximation. First we discuss the particle eigenstates, i.e., the stationary Wannier-Stark states. These states are proved to be extended states for the rational directions of the static field and localized states for the irrational directions. We find energy bands of the extended states and analyze the localized states. It is shown, in particular, that the localized honeycomb Wannier-Stark states are chaotic states with irregular dependence of the localization length on the static field magnitude. Second we discuss Bloch oscillations of the quantum particle. Irregular Bloch oscillations for irrational directions are observed. В© 2013 American Physical Society.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Tarasov A. S., Eremin E. V., Varnakov S. N., Ovchinnikov S. G., Zharkov S. M.
Заглавие : Magnetic-field- and bias-sensitive conductivity of a hybrid Fe/SiO 2/p-Si structure in planar geometry
Место публикации : J. Appl. Phys. - 2011. - Vol. 109, Is. 12. - Ст.123924. - P. - ISSN 0021-8979, DOI 10.1063/1.3600056
Ключевые слова (''Своб.индексиров.''): channel switching--comparative analysis--fe films--fe layer--ferromagnetic films--high temperature--hybrid structure--inversion layer--metal-insulator-semiconductors--negative magneto-resistance--planar geometries--positive magnetoresistance--schottky barriers--semiconductor substrate--temperature variation--weak localization--critical currents--electric resistance--ferromagnetic materials--geometry--magnetic fields--magnetoelectronics--magnetoresistance--metal insulator boundaries--metal insulator transition--mis devices--schottky barrier diodes--silicon--silicon compounds--switching circuits--transport properties--semiconducting silicon
Аннотация: Pronounced magnetic-field- and bias-sensitive features of the transport properties of a Fe/SiO2/p-Si hybrid structure in planar geometry at temperature variation are investigated. Comparative analysis of two Fe/SiO 2/p-Si samples, one with a continuous Fe film and the other with two electrodes formed from a Fe layer and separated by a micron gap, shows that these features are due to the metal-insulator-semiconductor (MIS) transition with a Schottky barrier near the interface between SiO2 and p-Si. Resistance of such a MIS transition depends exponentially on temperature and bias. In the structure with a continuous ferromagnetic film, the competition between conductivities of the MIS transition and the Fe layer results in the effect of current channel switching between the Fe layer and a semiconductor substrate. Within certain limits, this process can be controlled by a bias current and a magnetic field. Positive magnetoresistance of the structures at high temperatures is determined, most likely, by disorder-induced weak localization. In the structure with the gap, negative magnetoresistance is observed at certain temperature and bias. Its occurrence should be attributed to an inversion layer formed in the semiconductor near the SiO2/p-Si interface when MIS transition is in the inversion regime. В© 2011 American Institute of Physics.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R., Chesnokov I. Yu., Mantica G.
Заглавие : Cyclotron-Bloch dynamics of a quantum particle in a two-dimensional lattice. II. Arbitrary electric field directions
Место публикации : Phys. Rev. E: American Physical Society, 2012. - Vol. 86, Is. 4. - Ст.41146. - ISSN 1539-3755, DOI 10.1103/PhysRevE.86.041146
Примечания : Cited References: 15. - We thank Jean Bellissard and Italo Guarneri for illuminating comments on the nature of the energy spectrum for irrational beta. Computations for this work have been performed on the CSN4 cluster of INFN in Pisa. G. M. acknowledges the support of MIUR-PRIN project "Nonlinearity and Disorder in Classical and Quantum Transport Processes."
Предметные рубрики: MAGNETIC-FIELDS
LOCALIZATION
Аннотация: We study the quantum dynamics of a charged particle in a two-dimensional lattice, subject to constant and homogeneous electric and magnetic fields. We find that different regimes characterize these motions, depending on a combination of conditions, corresponding to weak and strong electric field intensities, rational or irrational directions of the electric field with respect to the lattice, and small or large values of the magnetic (Peierls) phase.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Kolovsky A. R.
Заглавие : Induced tunneling and localization for a quantum particle in tilted two-dimensional lattices
Коллективы : Russian Academy of Sciences through the SB RAS [29]
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 89, Is. 3. - Ст.035116. - ISSN 1098-0121, DOI 10.1103/PhysRevB.89.035116. - ISSN 1550-235X
Примечания : Cited References: 17. - The authors express their gratitude to D. N. Maksimov for useful remarks and acknowledge financial support of the Russian Academy of Sciences through the SB RAS integration project No. 29 Dynamics of atomic Bose-Einstein condensates in optical lattices.
Предметные рубрики: DYNAMIC LOCALIZATION
CHARGED-PARTICLE
OPTICAL LATTICE
ELECTRIC-FIELD
DIRAC POINTS
Аннотация: We consider a quantum particle in tilted two-dimensional lattices in the tight-binding approximations. We show that for certain lattice geometries the particle can freely move across the lattice in the direction perpendicular to the vector of the static force. This effect is argued to be analog of the photon-induced tunneling in driven one-dimensional lattices. We calculate the particle dispersion relation by using a method based on the Bogoliubov-Mitropolskii averaging technique from the theory of dynamical systems. This dispersion relation draws the analogy with driven one-dimensional lattices further by eventually showing band collapses when a control parameter is varied.
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Arkhipkin V. G., Myslivets S. A., Timofeev I. V., Shabanov A. V., Vetrov S. Ya., Timofeev V. P.
Заглавие : Photonic crystals with resonantly absorbing defects
Коллективы : International Conference on Laser and Fiber-Optical Networks Modeling (8; 2006 ; Jun 29-Jul 01; Kharkiv)
Место публикации : LFNM 2006: 8th International Conference on Laser and Fiber-Optical Networks Modeling, Proceedings: IEEE, 2006. - P.313-316. - ISBN 1-4244-0233-6
Примечания : Cited References: 12
Предметные рубрики: MICROCAVITIES
DISPERSION
SPECTRA
Ключевые слова (''Своб.индексиров.''): photonic crystal--photonic band gap--resonantly absorbing gas--light localization
Аннотация: We show that the defect mode of photonic crystal with resonantly absorbing gas in defect is splitted due to effects of linear absorption and dispersion of resonant atoms. The splitting and shape of the lines is very sensitive to an incidence-angle of radiation on PC. The cases of one and two defects are considered.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu J., Liu X., Yue C. L., Liu J. Y., Zhu H. W., He J. B., Wei J., Mao Z. Q., Antipina, L. Yu., Popov Z. I., Sorokin P.B., Liu T.J., Adams P.W., Radmanesh S. M. A., Spinu L., Ji H., Natelson D.
Заглавие : Enhanced electron coherence in atomically thin Nb3SiTe6
Коллективы : US National Science Foundation [DMR-1205469], NSF EPSCoR Cooperative Agreement [EPS-1003897], Louisiana Board of Regents; US Department of Energy, Office of Science, Basic Energy Sciences [DE-FG02-07ER46420], Russian Science Foundation [14-12-01217], Russian Federation [MK-6218.2015.2, 14.Z56.15.6218-MK], Leading Science School program [NSh-2886.2014.2], US Department of Energy, Office of Science, Basic Energy Sciences award [DE-FG02-06ER46337], US National Science Foundation under the NSF EPSCoR Cooperative Agreement [EPS-1003897]
Место публикации : Nat. Phys. - 2015. - Vol. 11, Is. 6. - P.471-476. - ISSN 1745, DOI 10.1038/NPHYS3321. - ISSN 17452481(eISSN)
Примечания : Cited References:38. - The authors are grateful to J. DiTusa for informative discussions. The work at Tulane is supported by the US National Science Foundation under grant DMR-1205469 and the NSF EPSCoR Cooperative Agreement No. EPS-1003897, with additional support from the Louisiana Board of Regents. P.W.A. and T.J.L. acknowledge the support of the US Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-FG02-07ER46420. L.Y.A. and P.B.S. acknowledge the support of the Russian Science Foundation (project #14-12-01217) and are grateful to the Joint Supercomputer Center of the Russian Academy of Sciences and 'Lomonosov' Research Computing Center for the opportunity of using a cluster computer for the quantum-chemical calculations. P.B.S. acknowledges a Grant of the President of the Russian Federation for government support of young PhD scientists MK-6218.2015.2 (project ID 14.Z56.15.6218-MK). Z.I.P. acknowledges the support of the Leading Science School program (No NSh-2886.2014.2). D.N. and H.J. acknowledge support through the US Department of Energy, Office of Science, Basic Energy Sciences award DE-FG02-06ER46337. The work at UNO is supported by the US National Science Foundation under the NSF EPSCoR Cooperative Agreement No. EPS-1003897, with additional support from the Louisiana Board of Regents.
Предметные рубрики: PHONON SCATTERING RATES
WEAK-LOCALIZATION
METAL-FILMS
Аннотация: It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene(1) and the large direct band gaps in MoS2 monolayers(2), arise from quantum confinement. However, the influence of reduced dimensions on electron-phonon (e-ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement(3-7) is expected to produce a suppression of e-ph interactions in 2D systems with rigid boundary conditions(6,7), experimental verification of this has remained elusive(8). Here, we show that the e-ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3SiTe6 atomic crystals. When the thickness of the Nb3SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e-ph interactions caused by quantum confinement of phonons.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev, Yu. V., Kazak N. V., Platunov M. S., Ivanova N. B., Bezmaternykh L. N., Arauzo A., Bartolome J., Ovchinnikov S. G.
Заглавие : Disorder- and correlation-induced charge carriers localization in oxyborate MgFeBO4, Mg0.5Co0.5FeBO4, CoFeBO4 single crystals
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 642. - P.232-237. - ISSN 0925, DOI 10.1016/j.jallcom.2015.04.056. - ISSN 18734669(eISSN)
Примечания : Cited References:32. - This work has been financed by Council for Grants of the President of the Russian Federation (Project Nos. NSh-2886.2014.2, SP-938.2015.5), Russian Foundation for Basic Research (Project Nos. 13-02-00958-a, 13-02-00358-a, 14-02-31051-mol-a). The work of one of coauthors (M.S.P.) was supported by the grant of KSAI "Krasnoyarsk Regional Fund of Supporting Scientific and Technological Activities'' and by the Program of Foundation for Promoting the Development of Small Enterprises in Scientific and Technical Sphere ("UMNIK'' program). Financial support from the Spanish MINECO MAT11/23791 and DGA IMANA project E-34 is acknowledged.
Предметные рубрики: WARWICKITE
Fe2OBO3
FeBO3
Ключевые слова (''Своб.индексиров.''): transition metal alloys and compounds--disordered system--semiconductors--electrical transport
Аннотация: The temperature dependence of the resistivity of single crystalline Mg1−xCoxFeBO4 samples with x = 0.0, 0.5, 1.0 is investigated for the temperature range (210–400 K). The conduction was found to be governed by Mott variable-range hopping (VRH) in the low-temperature range (T = 210–270 K) and by thermo-activation mechanism in the high-temperature range (T = 280–400 K). Microscopic electronic parameters, such as the density of the localized states near the Fermi level, localization length, the hopping length, and the activation energy have been obtained. The change of the activation energy observed at high-temperature range was attributed to local structure distortions around Fe and Co atoms. The complicated behavior of charge transfer mechanisms is discussed based on two approaches: atomic disorder and electron correlations.Температурная зависимость сопротивления монокристаллических образцов Mg1- XCoxFeBO4 с х = 0,0; 0.5, 1.0 исследована в интервале температур (210-400 К). Было установлено, что проводимость регулируется Мотт-переменной длиной прыжка (VRH) в области низких температур (T = 210-270 К) и термо-активационным механизмом в области высоких температур (Т = 280-400 К). Микроскопические электронные параметры, такие как плотность локализованных состояний вблизи уровня Ферми, длины локализации, длина прыжка, и энергия активации были получены. Изменение энергии активации наблюдается при высокой температурном Диапазоне, что было связано с локальными искажениями структуры вокруг Fe и Co атомов. Сложный механизм поведения переноса заряда обсуждается на основе двух подходов: атомный беспорядок и электронная корреляция.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tambasov I. A., Gornakov K. O., Myagkov V. G., Bykova L. E., Zhigalov V. S., Matsynin A. A., Yozhikova E. V.
Заглавие : Room temperature magneto-transport properties of nanocomposite Fe–In2O3 thin films
Место публикации : Physica B. - 2015. - Vol. 478. - P.135-137. - ISSN 0921-4526, DOI 10.1016/j.physb.2015.08.054
Примечания : Cited References: 28. - This study was supported by the Russian Foundation for Basic Research (Grants # 15-02-00948-A,), by the Council for Grants of the President of the Russian Federation (SP-317.2015.1), and by the program of Foundation for Promotion of Small Enterprises in Science and Technology (No 6662 FY2015) ("UMNIK" program).
Предметные рубрики: Doped In2O3 Films
High-performance
Indium oxide
Transistors
Magnetoresistance
Ferromagnetism
Ключевые слова (''Своб.индексиров.''): indium oxide--fe-in2o3 thin films--weak localization--disordered semiconductors
Аннотация: A ferromagnetic Fe–In2O3 nanocomposite thin film has been synthesized by the thermite reaction Fe2O3+In→Fe–In2O3. Measurements of the Hall carrier concentration, Hall mobility and magnetoresistance have been conducted at room temperature. The nanocomposite Fe–In2O3 thin film had n=1.94·1020 cm−3, μ=6.45 cm2/Vs and negative magnetoresistance. The magnetoresistance for 8.8 kOe was ~−0.22%.The negative magnetoresistance was well described by the weak localization and model proposed by Khosla and Fischer.
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9.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Ovchinnikov S. G.
Заглавие : Quasiparticle band structure, spectral weights and degree of d-electron localization in iron silicides
Коллективы : International seminar on ferroelastic physics, Международный семинар по физике сегнетоэластиков, Российская академия наук, Воронежский государственный технический университет
Место публикации : The Eighth Int. Sem. on Ferroelastic Phys.: book of abstracts. - 2015. - P.362

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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Ovchinnikov S. G.
Заглавие : Quasiparticle band structure, spectral weights and degree of d-electron localization in iron silicides
Коллективы : European Crystallographic Meeting
Место публикации : Acta Crystallogr. A: Wiley-Blackwell, 2015. - Vol. 71, Supplement. - Ст.s362. - ISSN 0108-7673, DOI 10.1107/S2053273315094590
Ключевые слова (''Своб.индексиров.''): strongly correlated electrons--delocalization
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grigoriev P. D., Korshunov M. M., Mogilyuk T. I.
Заглавие : Slow in-plane magnetoresistance oscillations in multiband quasi-two-dimensional metals
Коллективы : RFBR [16-02-00522, 16-02-00098]; Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1127-1132. - ISSN 1557-1939, DOI 10.1007/s10948-016-3373-x. - ISSN 1557-1947(eISSN)
Примечания : Cited References:73. - We are grateful to V.M. Pudalov, I. A. Nekrasov, and S.G. Ovchinnikov for useful discussions. We acknowledge the partial support by RFBR (Grants 16-02-00522 and 16-02-00098) and the President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2).
Предметные рубрики: High-temperature superconductivity
High magnetic-fields
Iron-based materials
Conductors
Localization
Weak
Ключевые слова (''Своб.индексиров.''): fermi surface--quantum oscillations--fe-based superconductors--slow--oscillations--magnetoresistance
Аннотация: Slow oscillations (SlO) of magnetoresistance is a convenient tool to measure electronic structure parameters in quasi-two-dimensional metals. We study the possibility to apply this method to multi-band conductors, e.g., to iron-based high-temperature superconducting materials. We show that SlO can be used to measure the interlayer transfer integral in multi-band conductors similar to single-band metals. In addition, the SlO allow to measure and compare the effective masses or the electron scattering rates in various bands.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Interplay between Anderson and Stark Localization in 2D Lattices
Коллективы :
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2008. - Vol. 101, Is. 19. - Ст.190602. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.101.190602
Примечания : Cited References: 20. - The author gratefully acknowledges discussions with X. Zotos and financial support under the Project No. FP6032980-2 within the 6th Framework Programme.
Предметные рубрики: BOSE-EINSTEIN CONDENSATE
CHARACTERISTIC VECTORS
INFINITE DIMENSIONS
BLOCH OSCILLATIONS
BORDERED MATRICES
EIGENFUNCTIONS
SUPERLATTICES
AC
Аннотация: This Letter studies the dynamics of a quantum particle in 2D lattices with on-site disorder in the presence of a static field. It is shown that the particle is localized along the field direction, while in the orthogonal direction to the field it shows diffusive dynamics for algebraically large times. For weak disorder an analytical expression for the diffusion coefficient is obtained by mapping the problem to a band random matrix. This expression is confirmed by numerical simulations of the particle's dynamics, which also indicate the existence of a universal equation for the diffusion coefficient, valid for an arbitrary disorder strength.
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13.

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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14.

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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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Ovchinnikov S. G., Abd-Elmeguid M. M., Ivanova N. B.
Заглавие : Electronic properties of Fe1-xVxBO3 at ambient conditions and at high pressure
Разночтения заглавия :авие SCOPUS: Electronic properties of Fe1-xVx-BO3 at ambient conditions and at high pressure
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2005. - Vol. 17: 2nd International Symposium on Physics of Solids Under High Pressure Using Nuclear Probes (JUL 20-24, 2004, Cologne, GERMANY), Is. 11. - P.S795-S800. - ISSN 0953-8984, DOI 10.1088/0953-8984/17/11/008
Примечания : Cited References: 16
Предметные рубрики: FEBO3 SINGLE-CRYSTALS
SOLID-SOLUTIONS
BAND-STRUCTURE
TRANSITION
MOSSBAUER
MAGNETIZATION
MODEL
VBO3
Ключевые слова (''Своб.индексиров.''): electronic properties--ferrimagnetic materials--high pressure effects--high temperature superconductors--metal insulator transition--single crystals--superconductivity--thermal effects--carrier localization--correlation effects--critical pressure--semiconducting behavior--oxide superconductors
Аннотация: We present the results of an in-plane resistivity study of the solid solutions Fe1-xVxBO3. The measurements were made on single crystals with concentration x = 0.02, 0.13, 0.18, 0.3, 0.95, 1.0 in the temperature range 220-600 K. Semiconducting behaviour for samples with x = 0.13 was found. Mott variable-range-hopping transport rho(T) = rho(0)exp(T*/T)(alpha) has been observed with alpha = 1/4 at T 290 K, suggesting carrier localization. Above this temperature the activation-type conductivity, with activation energies, E-a, about 1 eV for all samples, is observed. The possible electronic states and band structure of Fe1-xVx BO3 crystals are discussed in the different pressure ranges: P P-c(Fe), p(c)(Fe) p p(c)(V) P P-c(V) where p(c)(Fe) P-c(V) are the critical pressure values for FeBO3 and VBO3, respectively.
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16.

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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17.

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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18.

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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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mendez-Bermudez J. A., Luna-Acosta G. A., Seba P., Pichugin K. N.
Заглавие : Understanding quantum scattering properties in terms of purely classical dynamics: Two-dimensional open chaotic billiards
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2002. - Vol. 66, Is. 4. - Ст.46207. - ISSN 1539-3755, DOI 10.1103/PhysRevE.66.046207
Примечания : Cited References: 34
Предметные рубрики: BALLISTIC-TRANSPORT
POINCARE SECTIONS
CAVITIES
EIGENFUNCTIONS
LOCALIZATION
CHANNEL
Ключевые слова (''Своб.индексиров.''): chaos theory--electron tunneling--laser applications--nonlinear systems--probability--waveguide components--chaotic motion--microlasers--quantum scattering--scattering probability--quantum theory--article
Аннотация: We study classical and quantum scattering properties of particles in the ballistic regime in two-dimensional chaotic billiards that are models of electron- or micro-waveguides. To this end we construct the purely classical counterparts of the scattering probability (SP) matrix \S(n,m)\(2) and Husimi distributions specializing to the case of mixed chaotic motion (incomplete horseshoe). Comparison between classical and quantum quantities allows us to discover the purely classical dynamical origin of certain general as well as particular features that appear in the quantum description of the system. On the other hand, at certain values of energy the tunneling of the wave function into classically forbidden regions produces striking differences between the classical and quantum quantities. A potential application of this phenomenon in the field of microlasers is discussed briefly. We also see the manifestation of whispering gallery orbits as a self-similar structure in the transmission part of the classical SP matrix.
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