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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Crossing resonance of stochastically interacting wave fields
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 116, Is. 2. - P.206-222. - ISSN 1063-7761, DOI 10.1134/S1063776113020118
Примечания : Cited References: 42. - We are grateful to V. V. Val'kov and A. F. Sadreev for useful discussions. This work was supported by the Presidium of the Russian Academy of Sciences (Program no. 24.29), the Dynasty Foundation (Program for Support of Young Scientists), the Federal Target Program (state contract no. 14.B37.21.0730), and the Special Program for Siberian Federal University of the Ministry of Education and Science of the Russian Federation.
Предметные рубрики: CRYSTALS
SYSTEMS
ALLOYS
MEDIA
Аннотация: The dynamic susceptibilities (Green's functions) of the system of two interacting wave fields of different physical natures with a stochastically inhomogeneous coupling parameter between them with zero mean value have been examined. The well-known self-consistent approximation taking into account all diagrams with noncrossing correlation/interaction lines has been generalized to the case of stochastically interacting wave fields. The analysis has been performed for spin and elastic waves. The results obtained taking into account the processes of multiple scattering of waves from inhomogeneities are significantly different from those obtained for this situation earlier in the Bourret approximation [R.C. Bourret, Nuovo Cimento 26, 1 (1962)]. Instead of frequencies degeneracy removal in the wave spectrum and the splitting of resonance peaks of dynamic susceptibilities, a wide single-mode resonance peak should be observed at the crossing point of the unperturbed dispersion curves. The fine structure appears at vertices of these wide peaks in the form of a narrow resonance on the Green's-function curve of one field and a narrow antiresonance on the vertex of the Green's-function curve of the other field.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ikonnikov D. A., Malakhovskii A. V., Sukhachev A. L., Zaitsev A. I., Aleksandrovsky A. S., Jubera V.
Заглавие : Spectroscopic properties of Nd3+ in orthorhombic δ-BiB3O6 crystal
Место публикации : Opt. Mater.: ELSEVIER SCIENCE BV, 2012. - Vol. 34, Is. 11. - P.1839-1842. - ISSN 0925-3467, DOI 10.1016/j.optmat.2012.05.016
Примечания : Cited References: 23. - The work was supported by Ministry of Education and Science of Russian Federation (Contract 16.740.11.0150), by Russian Foundation for Basic Researches Grant 12-02-00026, Grant of President of Russian Federation for support of leading scientific schools No. SS-4828.2012.2, Grant No. SFU.F12, and Projects No. 28, 43 and No. 101 of SB RAS.
Предметные рубрики: SPECTRAL-LINE INTENSITIES
RARE-EARTH IONS
LASER CRYSTAL
NdAl3(BO3)(4) NAB
OPTICAL-SPECTRA
BiB3O6
SYSTEMS
GROWTH
Er3+
Tm3+
Ключевые слова (''Своб.индексиров.''): neodymium--orthorhombic bismuth triborate--absorption--judd-ofelt analysis
Аннотация: Absorption spectra of the Nd3+ ions in an orthorhombic δ-BiB3O6 single crystal were measured in the spectral range 11,000-20,500 cm-1. The f-f transition intensities were analyzed in terms of the Judd-Ofelt theory, and the following parameters of the theory were obtained: Ω2 = 6.35 × 10-20 cm2, Ω4 = 4.86 × 10-20 cm 2, and Ω6 = 11.233 × 10-20 cm 2. The strengths, spontaneous emission probabilities, branching ratios, spectroscopic quality factor and excited state radiative lifetime were calculated for laser transitions from the 4F3/2 state to 4IJ manifold. Spectroscopic properties of Nd 3+:δ-BiB3O6 crystal favor lasing at 1.3 μm, where this crystal possesses near non-critical phase matching for second harmonic generation. © 2012 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V.
Заглавие : Anomalous resistivity and the electron-polaron effect in the two-band hubbard model with one narrow band
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2012. - Vol. 25, Is. 5. - P.1379-1382. - ISSN 1557-1939, DOI 10.1007/s10948-012-1523-3
Примечания : Cited References: 28. - We are grateful to P. Fulde, Yu. Kagan, K. I. Kugel, N.V. Prokof'ev, P. Nozieres, and C. M. Varma for the numerous stimulating discussions. We acknowledge financial support of the RFBR Grant No. 11-02-00741.
Предметные рубрики: FERMI GAS
SUPERCONDUCTIVITY
SUPERFLUIDITY
TEMPERATURE
REPULSION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): electron-polaron effect--two-band hubbard model--marginality--anomalous resistivity
Аннотация: We search for anomalous normal and superconductive behavior in the two-band Hubbard model with one narrow band. We analyze the influence of the electron–polaron effect and the Altshuler–Aronov effect on effective mass enhancement and scattering times of heavy and light components in the clean case. We find anomalous behavior of resistivity at high temperatures TW∗hT W_{h}. *} both in 3D and 2D situations. The SC instability in the model is governed by an enhanced Kohn–Luttinger effect for p-wave pairing of heavy electrons via polarization of light electrons.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sokolov A. E., Edelman I. S., Zabluda V. N., Petrakovskaya E. A., Aleksandrovsky A. S., Shubin A. A., Trukhan S. N., Mart'yanov O. N.
Заглавие : Magneto-optical activity of crude oil and its heavy fractions
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 112, Is. 5. - P.755-762. - ISSN 0030-400X, DOI 10.1134/S0030400X12050165
Примечания : Cited References: 18. - This work was performed under Interdisciplinary Integration Project no. 118 of the Siberian Branch of the Russian Academy of Sciences (2009-2011).
Предметные рубрики: MAGNETIC CIRCULAR-DICHROISM
SINGLE-CRYSTALS
SPECTROSCOPY
EPR
ABSORBENCY
PORPHYRIN
SYSTEMS
Аннотация: We have experimentally studied optical and magneto-optical spectra of solutions of crude oils of different origin and their heavy fractions in the visible spectral range. Magnetic circular dichroism of oil in the wavelength range similar to 550 nm has been revealed. We show that the shape of the spectra of this dichroism depends on the origin of crude oil, with the magnetic dichroism magnitude being proportional to the concentration of the oil in the solution. A comparison of the data of magneto-optical spectroscopy with electron paramagnetic resonance spectra and chemical composition of samples has allowed us to conclude that the observed magneto-optical activity is determined by the occurrence of VO2+ complexes in the oil samples. The revealed magneto-optical activity of crude oil can form the basis of a unique method of analysis of the composition and properties of oils of different origin and heavy fractions thereof.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krinitsyn A., Nikolaev S., Ovchinnikov S. G.
Заглавие : Cluster size and shape effect on the electronic structure of the Hubbard model within the norm-conserving cluster perturbation theory
Коллективы : Siberian Federal University [F-11]; Presidium of RAS Program [20.7]; [NSh-1044.2012.2]; [MK-1168.2012.2]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2014. - Vol. 27, Is. 4. - P.955-963. - ISSN 1557-1939, DOI 10.1007/s10948-013-2418-7. - ISSN 1557-1947
Примечания : Cited References: 59. - This work was supported by Grants NSh-1044.2012.2 and MK-1168.2012.2, Siberian Federal University: Grant F-11, and the Presidium of RAS Program 20.7.
Предметные рубрики: NARROW ENERGY-BANDS
CUPRATE SUPERCONDUCTORS
PHOTOEMISSION SPECTRA
PSEUDOGAP
ANTIFERROMAGNET
EXCITATIONS
EVOLUTION
SYSTEMS
PHASE
STATE
Ключевые слова (''Своб.индексиров.''): cluster perturbation theory--hubbard model--strong correlations--density of states--fermi surface
Аннотация: Within a new norm-conserving approach to the cluster perturbation theory (CPT) for the 2d Hubbard model we study the effect of the cluster size and shape on the electronic structure. We have compared two type of clusters, 4-cluster (2x2) and 5-cluster (cruciform of 5 atoms). With 4-cluster we can treat exactly the first and second neighbours correlations, C (1) and C (2). With 5-cluster the third neighbour correlations C (3) are also treated exactly. The band structure in the CPT with 4- and 5-clusters differs remarkably. The quasiparticle spectral weight map for 5-clusters is very similar to the Quantum Monte Carlo (QMC) and the variational CPT data. With increasing doping, small hole Fermi surface transforms into conventional Fermi-liquid type large Fermi surface through Lifshitz quantum phase transitions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Tambasov I. A., Bayukov O. A., Zhigalov V. S., Bykova L. E., Mikhlin Yu. L., Volochaev M. N., Bondarenko G. N.
Заглавие : Solid state synthesis and characterization of ferromagnetic nanocomposite Fe-In2O3 thin films
Место публикации : J. Alloys Compd.: Elsevier Science, 2014. - Vol. 612. - P.189-194. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.05.176. - ISSN 1873-4669
Примечания : Cited References: 56
Предметные рубрики: HIGH-TEMPERATURE FERROMAGNETISM
PHASE-FORMATION
In2O
OXIDE
NANOPARTICLES
CO
SEMICONDUCTORS
NANOCRYSTALS
COMBUSTION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): thermite reactions--reactive films--ferromagnetic nanocomposite films--transparent conducting oxides
Аннотация: We have successfully synthesized ferromagnetic Fe-In2O 3 nanocomposite thin films for the first time using the thermite reaction Fe2O3 + In = In2O3 + Fe. The initial In/Fe2O3 bilayers were obtained by the deposition of In layers on α-Fe2O3 films. The reaction occurs in a self-propagating mode in a homogeneous thermal film plane field at heating rates above 20 K/s and at temperatures above initiation temperature T[[d]]in[[/d]] ~ 180 °C. At heating rates lower than 20 K/s the mixing of the In and Fe2O3 layers occurs across the whole In/Fe2O3 interface and the synthesis of the ferromagnetic α-Fe phase starts above the initiation temperature T[[d]]in[[/d]] = 180 °C. X-ray diffraction, X-ray photoelectron spectroscopy, Mossbauer spectroscopy, transmission electron microscopy and magnetic measurements were used for phase identification and microstructure observation of the synthesized Fe-In2O3 samples. The reaction products contain (1 1 0) textured α-Fe nanocrystals with a diameter around 100 nm and surrounded by an In2O3 matrix. These results enable new efficient low-temperature methods for synthesizing ferromagnetic nanocomposite films containing ferromagnetic nanoclusters embedded in transparent conducting oxides. © 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger superconductivity in idealized doped graphene
Коллективы : Program of the Division of Physical Sciences of the Russian Academy of Sciences [11.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Council of the President of the Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2014. - Vol. 188. - P.61-66. - ISSN 0038-1098, DOI 10.1016/j.ssc.2014.03.001. - ISSN 1879-2766
Примечания : Cited References: 31. - This work was supported by the Program of the Division of Physical Sciences of the Russian Academy of Sciences (Project 11.3.1), and the Russian Foundation for Basic Research (Projects 14-02-00058 and 14-02-31237). One of the authors (M.M.K.) acknowledges the support of the Council of the President of the Russian Federation (Project MK-526.2013.2), and the Dynasty Foundation.
Предметные рубрики: REPULSIVE INTERACTIONS
HUBBARD-MODEL
SUPERFLUIDITY
INSTABILITY
MECHANISM
DENSITY
SYSTEMS
Ключевые слова (''Своб.индексиров.''): graphene--superconductivity
Аннотация: Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter. (C) 2014 Elsevier Ltd. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kim J., Struzhkin V. V., Ovchinnikov S. G., Orlov Yu. S., Shvyd'ko Y., Upton M. H., Casa D., Gavriliuk A. G., Sinogeikin S. V.
Заглавие : Pressure-induced spin transition and evolution of the electronic excitations of FeBO3: Resonant inelastic x-ray scattering results
Коллективы : DOE [DE-FG02-02ER45955]; U.S. DOE [DE-AC02-06CH11357]; President of Russia Grants [NSh-1044.2012.2, MK-1168.2012.2]; Presidium of the Russian Academy of Sciences Program 2, RFFI [12-02-90410, 12-02-31543]; Siberian Federal University Grant [F11]; Russian Foundation for Basic Research grants from RAS programs [14-0200483, 15-02-03770]; FCP [GK-P891]
Место публикации : Europhys. Lett. - 2014. - Vol. 108, Is. 3. - Ст.37001. - ISSN 0295-5075, DOI 10.1209/0295-5075/108/37001. - ISSN 1286-4854
Примечания : Cited References: 47. - High-pressure work was supported by DOE under Contract No. DE-FG02-02ER45955. The use of the Advanced Photon Source at the Argonne National Laboratory was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. SGO and YuO acknowledge the President of Russia Grants NSh-1044.2012.2 and MK-1168.2012.2, the Presidium of the Russian Academy of Sciences Program 2, RFFI Grants 12-02-90410 and 12-02-31543, FCP GK-P891, and the Siberian Federal University Grant F11. AGG acknowledges support from the Russian Foundation for Basic Research grants 14-02-00483 and 15-02-03770 from RAS programs "Strongly correlated electron systems", "Elementary particle physics, fundamental nuclear physics and nuclear technologies".
Предметные рубрики: LOWER-MANTLE
SPECTRA
STATE
EMISSION
COLLAPSE
SYSTEMS
OXIDES
METAL
Аннотация: A high-pressure resonant inelastic x-ray scattering (RIXS) of FeBO3 at the Fe K pre-edge has been carried out to study the evolution of electronic excitations through the pressure-induced spin transition. Systematic peak shifts with insignificant peak width change are observed with increasing pressure in the high-spin state. An electronic transition occurs in tandem with the high-spin to low-spin transition, observed as the emergence of multiple new low-energy peaks in the spectra. The energy gap is reduced due to these low-energy peaks, not a peak width broadening. The observed electronic excitations are associated with dd excitations, which are calculated using a full-multiplet theory. We consider changes in crystal-field splitting and covalency to explain the observed peak shifts in the high-spin state. The new peaks that emerge upon the high- to low-spin transition are compared with dd excitations for the low-spin configuration. Copyright (C) EPLA, 2014
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arkhipkin V. G., Timofeev I. V.
Заглавие : Adiabatic propagation of short pulses under conditions of electromagnetically induced transparency
Место публикации : Quantum Electron.: Turpion LTD, 2000. - Vol. 30, Is. 2. - P.180-184. - ISSN 1063-7818, DOI 10.1070/QE2000v030n02ABEH001683
Примечания : Cited References: 31
Предметные рубрики: POPULATION TRANSFER
LASER-PULSES
INTERFERENCE
ENHANCEMENT
COHERENCE
QUANTUM
SYSTEMS
INDEX
Аннотация: The spatial and temporal dynamics of two short pulses propagating in an optically dense medium of resonant three-level Lambda-atoms is investigated numerically and analytically. The maximum coherence for the Raman transition due to coherent population trapping. it is shown that, at the initial stage of propagation, the waveforms of such pulses only slightly change along the length of the medium, which may considerably exceed the length of linear absorption for a single weak pulse. As the length of the absorbing medium increases, the energy of the probe (first) pulse is completely transferred into the second (control) pulse.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Pilipchuk A. S.
Заглавие : Bound states in the continuum in zigzag quantum wire enforced by a finger gate
Коллективы : Russian Foundation for Basic Research [14-12-00266]
Место публикации : JETP Letters. - 2015. - Vol. 100, Is. 9. - P.585-590. - ISSN 0021, DOI 10.1134/S0021364014210139. - ISSN 10906487(eISSN)
Примечания : Cited References:41. - This work was supported by the Russian Foundation for Basic Research(project no. 14-12-00266).
Предметные рубрики: WAVE-GUIDE
DOUBLE-BEND
SYSTEMS
TRANSMISSION
RESONANCES
ELECTRON
Аннотация: We consider electron transport in a zigzag quantum wire by the effect of finger gate potential. Using a non-Hermitian effective Hamiltonian, we calculate resonance positions and widths to show that the resonance widths are easily governed by the gate potential. In particular, the resonance width can be enforced to be equal to zero, which leads to an electron localization with the Fermi energy embedded in the propagation band of the wire, i.e., the bound state in the continuum (BSC). We show that, for positive values of the potential, a zigzag wire becomes a Fabry-Perot resonator to give rise to BSC too.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arauzo A., Kazak N. V., Ivanova N. B., Platunov M. S., Knyazev Yu. V., Bayukov O. A., Bezmaternykh L. N., Lyubutin I. S., Frolov K. V., Ovchinnikov S. G., Bartolome J.
Заглавие : Spin-glass behavior in single crystals of hetero-metallic magnetic warwickites MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4
Коллективы : MINECO Project [MAT11/23791, MAT2014-53921-R], DGA IMANA project [E-34], Russian Foundation for Basic Research [13-02-00958, 13-02-00358, 14-02-31051-mol-a], Council for Grants of the President of the Russian Federation [NSh-2886.2014.2, SP-938.2015.5], program of Foundation for Promotion of Small Enterprises in Science and Technology ("UMNIK" program)
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2015. - Vol. 392. - P.114-125. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.05.006. - ISSN 18734766(eISSN)
Примечания : Cited References:36. - This work has been financed by the MINECO Project MAT11/23791, MAT2014-53921-R and DGA IMANA project E-34, Russian Foundation for Basic Research (project Nr. 13-02-00958, 13-02-00358 and 14-02-31051-mol-a), Council for Grants of the President of the Russian Federation (project Nr. NSh-2886.2014.2 and SP-938.2015.5). The work of one of coauthors (M.S.P.) was supported by the program of Foundation for Promotion of Small Enterprises in Science and Technology ("UMNIK" program).
Предметные рубрики: SYSTEMS
CHAIN
Fe
SUSCEPTIBILITY
Fe2OBO3
ENERGY
Ключевые слова (''Своб.индексиров.''): warwickites--spin glass--entanglement--exchange interaction
Аннотация: Magnetic properties of heterometallic warwickites MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 are presented, highlighting the effect of Co substitution on the magnetic properties of these compounds. The analysis of magnetization and heat capacity data has shown that these compounds exhibit a spin-glass transition below TSG=10, 20 and 22 K, respectively. Using zero field ac susceptibility as entanglement witness we find that the low dimensional magnetic behavior above TSG show quantum entanglement behavior χ(Τ)∝T−α(Τ) up to TE≈130 K. The α parameters have been deduced as a function of temperature and Co content, indicating the existence of random singlet phase in this temperature region. Above TE the paramagnetism is interpreted in terms of non-entangled spins giving rise to Curie–Weiss paramagnetism. The different intra- and inter-ribbon exchange interaction pathways have been calculated within a simple indirect coupling model. It is determined that the triangular motifs in the warwickite structure, together with the competing interactions, induce frustration. The spin-glass character is explained in terms of the substitutional disorder of the Mg, Fe and Co atoms at the two available crystallographic sites, and the frustration induced by the competing interactions. The Co substitution induces uniaxial anisotropy, increases the absolute magnetization and increases the spin-glass freezing temperature. The entanglement behavior is supported in the intermediate phase irrespective of the introduction of anisotropy by the Co substitution.Представлены магнитные свойства гетерометаллических варвикитов MgFeBO4, Mg0.5Co0.5FeBO4 и CoFeBO4, с выделением эффекта замещения Co на магнитные свойства этих соединений. Анализ данных намагниченности и теплоемкости показал, что эти соединения обладают спин-стекольным переходом ниже TSG=10, 20 и 22 К соответственно. Используя нулевого поля для переменной восприимчивости, мы находим, что низкоразмерных магнитное поведение выше TSG показать квантовая запутанность поведение χ (Τ) αT? α (Τ) до TEE130 К. Параметры α были выведены в зависимости от температуры и содержание Со, что указывает на существование случайного синглетного фазы в этой области температур. Над TE в Парамагнетизм интерпретируется в терминах перепутывания спинов, приводящих к парамагнетизму Кюри-Вейсса. Различные внутри- и обменного взаимодействия между направлениями были рассчитаны в модели простой косвенной связи. Установлено, что треугольные мотивы в структуре варвикита, вместе с конкурирующими взаимодействиями, вызывают фрустрацию. Характер спинового стекла объясняется в условиях беспорядка замещения атомов Mg, Fe и Co в двух доступных кристаллографических позициях, и фрустрацию, индуцированную конкурирующими взаимодействиями. Замена Со вызывает одноосную анизотропию, увеличивает абсолютную намагниченность и повышает температуру замерзания спинового стекла. Запутанность Поведения поддерживается в промежуточной фазе, независимо от анизотропии из-за введения замещения Со.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shauro V. P.
Заглавие : Exact solutions for time-optimal control of spin I=1 by NMR
Коллективы : Russian Foundation for Basic Research [14-07-31086]
Место публикации : Quantum Inf. Process.: Springer, 2015. - Vol. 14, Is. 7. - P.2345-2355. - ISSN 1570, DOI 10.1007/s11128-015-0999-8. - ISSN 15731332(eISSN)
Примечания : Cited References:34. - The author thanks V.E. Zobov for fruitful discussions. This study was supported by the Russian Foundation for Basic Research, Project No. 14-07-31086.
Предметные рубрики: QUANTUM COMPUTATION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): quantum gate--qutrit--time-optimal control--nuclear magnetic resonance
Аннотация: We consider the problem of time-optimal control of quadrupole nucleus with the spin I = 1 by NMR. In contrast to the conventional methods based on selective pulses, the control is implemented using nonselective pulses separated by free-evolution intervals. Using the Cartan decomposition, the system of equations is obtained for finding parameters of a control field. Partial time-optimal solutions for the important single-qutrit gates (selective rotations and quantum Fourier transform) are found. The strong dependence of minimum gate implementation times on global phase of the gate is observed. The analytical values of minimum times are consistent with the numerical data.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Maksimov D. N., Pilipchuk A. S.
Заглавие : Gate controlled resonant widths in double-bend waveguides: bound states in the continuum
Коллективы : Russian Science Foundation [14-12-00266]
Место публикации : J. Phys.: Condens. Matter: IOP Publishing, 2015. - Vol. 27, Is. 29. - Ст.295303. - ISSN 0953, DOI 10.1088/0953-8984/27/29/295303. - ISSN 1361648X(eISSN)
Примечания : Cited References:52. - This work is supported by the Russian Science Foundation through Grant No. 14-12-00266. AS is grateful K-F Berggren for discussions.
Предметные рубрики: CIRCULAR BENDS
NUCLEAR REACTIONS
FANO RESONANCES
UNIFIED THEORY
QUANTUM
TRANSMISSION
TRANSPORT
SYSTEMS
Ключевые слова (''Своб.индексиров.''): double-bent waveguide--effective non-hermittian hamiltonian--bound--states in the continuum
Аннотация: We consider quantum transmission through double-bend Pi- and Z-shaped waveguides controlled by the finger gate potential. Using the effective non-Hermitian Hamiltonian approach we explain the resonances in transmission. We show a difference in transmission in the short waveguides that is the result of different chirality in Z and Pi waveguides. We demonstrate that the potential selectively affects the resonant widths resulting in the occurrence of bound states in the continuum.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Timofeev I. V., Gunyakov V. A., Sutormin V. S., Myslivets S. A., Arkhipkin V. G., Vetrov S. Ya., Lee W., Zyryanov V. Ya.
Заглавие : Geometric phase and ο-mode blueshift in a chiral anisotropic medium inside a Fabry-Pérot cavity
Место публикации : Phys. Rev. E: American Physical Society, 2015. - Vol. 92, Is. 5. - Ст.052504. - ISSN 15393755 (ISSN), DOI 10.1103/PhysRevE.92.052504
Примечания : Cited References: 92. - This work was supported in part by Russian Foundation for Basic Research Grants No. 14-02-31248 and No. 15-02-06924; Ministry of Education and Science of the Russian Federation under the Government program, Project No. 3.1276.2014/K; and the Ministry of Science and Technology of Taiwan under Grant No. NSC 103-2923-M-009-003-MY3 through an NSC–SB RAS joint project
Предметные рубрики: NEMATIC LIQUID-CRYSTAL
DIMENSIONAL PHOTONIC CRYSTAL
OPTICAL-PROPERTIES
ELECTROMAGNETIC PROPAGATION
DISPLAYS
SYSTEMS
FILTER
LIGHT
CELL
FORMULATION
Аннотация: Anomalous spectral shift of transmission peaks is observed in a Fabry-Pérot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method, and geometrically using the generalized Mauguin-Poincaré rolling cone method. The o-mode blueshift is measured for a 4-methoxybenzylidene-4′-n-butylaniline twisted-nematic layer inside the Fabry-Pérot cavity. The twist is electrically induced due to the homeoplanar-twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model. © 2015 American Physical Society.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S.
Заглавие : Quantum renormalizations in anisotropic multisublattice magnets and the modification of magnetic susceptibility under irradiation
Коллективы : Russian Foundation for Basic Research [13-02-00523, 14-02-31237, 15-42-04372]
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 121, Is. 5. - P.860-877. - ISSN 1063-7761, DOI 10.1134/S1063776115110175. - ISSN 1090-6509(eISSN)
Примечания : Cited References:46. - This work was supported by the Russian Foundation for Basic Research, project nos. 13-02-00523, 14-02-31237, and 15-42-04372
Предметные рубрики: SINGLE-CHAIN MAGNETS
GLAUBER MODEL
EASY-PLANE
ARRANGEMENT
SYSTEMS
IONS
Аннотация: The dispersion equation of a strongly anisotropic one-dimensional magnet catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 containing alternating high-spin (HS) (S = 2) and low-spin (LS) (S = 1/2) iron ions is obtained by the diagram technique for Hubbard operators. The analysis of this equation yields six branches in the excitation spectrum of this magnet. It is important that the crystal field for ions with spin S = 2 is described by the Hamiltonian of single-ion easy-plane anisotropy, whose orientation is changed by 90° when passing from one HS iron ion to another. The U(N) transformation technique in the atomic representation is applied to diagonalize a single-ion Hamiltonian with a large number of levels. It is shown that the modulation of the orientation of easy magnetization planes leads to a model of a ferrimagnet with easy-axis anisotropy and to the formation of energy spectrum with a large gap. For HS iron ions, a decrease in the mean value of the spin projection due to quantum fluctuations is calculated. The analysis of the specific features of the spectrum of elementary excitations allows one to establish a correspondence to a generalized Ising model for which the magnetic susceptibility is calculated in a wide range of temperatures by the transfer-matrix method. The introduction of a statistical ensemble that takes into account the presence of chains of different lengths and the presence of iron ions with different spins allows one to describe the experimentally observed modification of the magnetic susceptibility of the magnet under optical irradiation.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zinenko V. I.
Заглавие : The effect of structural ordering on the magnetic, electronic, and optical properties of the LaPbMnSbO6 double perovskite
Коллективы : Russian Foundation for Basic Research [15-02-00340-a]; Russian Federation [NSH-924.2014.2]
Место публикации : J. Alloys Compd.: Elsevier Science, 2016. - Vol. 671. - P.184-191. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2016.02.085. - ISSN 1873-4669(eISSN)
Примечания : Cited References:32. - This work was supported by the Russian Foundation for Basic Research, project no. 15-02-00340-a and the Grant of the President of the Russian Federation for Support of Leading Scientific Schools no. NSH-924.2014.2.
Предметные рубрики: SYSTEMS
NI
CO
Ключевые слова (''Своб.индексиров.''): ab initio calculation--double perovskite--magnetic materials--optical--properties--electronic properties--magnetic properties--layer compound
Аннотация: The interplay between the magnetic, electronic, and optical properties and the cation structural ordering in the LaPbMnSbO6 double perovskite is studied using the Vienna Ab Initio Simulation Package (VASP). The layer and rock-salt cation ordering types are investigated. Both of them are of great importance. The rock-salt ordering of B-site cations is one of the most frequently met cation ordering types in double perovskites; the layer ordering of both cations, which can be considered as a heterostructure, is interesting for fundamental research and experimental synthesis. It was established that the properties of the two investigated structures are strongly different. The compound with the layered structure exhibits the behavior typical of a semimetal with the ferromagnetic configuration of magnetic moments, which is unusual for a double perovskite. The rock-salt structure behaves as an antiferromagnetic insulator. Another surprising feature of the structure with the layer ordering is the coexistence of a polar phase and the metal-type conductivity. The calculated optical characteristics of the two ordered structures are compared with the experimental dates. (C) 2016 Elsevier B.V. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Marienko M. S., Val'kov V. V.
Заглавие : Triplet p-Wave Superconductivity in the Low-Density Extended Hubbard Model with Coulomb Repulsion
Разночтения заглавия :авие SCOPUS: Triplet p-wave superconductivity in the low-density extended hubbard model with Coulomb repulsion
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 12. - P.725-730. - ISSN 0021-3640, DOI 10.1134/S0021364011120083
Примечания : Cited References: 42. - We acknowledge useful with A. V. Chubukov, A.S. Alexandrov, I.A. Fomin, K.I. Kugel, and V. V. Kabanov for stimulating discussions. This work was supported by the Russian Foundation for Basic Research (project nos. 11-02-00708 and 11-02-00741). M.S.M acknowledges the support of the US Department of Energy (award no. DE-FG02-08ER64623, Hofstra University Center for Condensed Matter).
Предметные рубрики: T-J MODEL
FERMI GAS
SUPERFLUID TRANSITION
PHASE-SEPARATION
SYSTEMS
TEMPERATURES
BEHAVIOR
LIQUID
POINT
STATE
Аннотация: We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb repulsion between electrons on neighboring sites in the limit of low electron density (n(el) - 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U V W (U and V are the onsite and the intersite Coulomb repulsions, respectively, and W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.
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18.

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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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Valkov V. V.
Заглавие : Anomalous resistivity and superconductivity in the two-band Hubbard model with one narrow band (Review)
Место публикации : Low Temp. Phys. - 2011. - Vol. 37, Is. 1. - P.69-82. - ISSN 1063-777X, DOI 10.1063/1.3552118; \b Физика низких температур
Примечания : Cited References: 62. - We thank A.S. Alexandrov, A.F. Andreev, M.A. Baranov, Yu. Bichkov, A.V. Chubukov, D.V. Efremov, A.S. Hewson, K.A. Kikoin, F.V. Kusmartsev, P. Nozieres, T.M. Rice, A.O. Sboychakov, P. Thalmeer, C.M. Varma, D. Vollhardt, P. Woelfle, A. Yaresko and, especially, P. Fulde, Yu. Kagan, K.I. Kugel, and N.V. Prokof'ev for many simulating discussions on this subject and acknowledge the financial support of RFBR grants # 08-02-00224 and 08-02-00212. M.Yu.K. is also grateful to the Leverhulme trust for a grant to visit Loughborough University, where this work was completed.
Предметные рубрики: FERMI-LIQUID BEHAVIOR
MAGNETIC-ALLOYS
HEAVY
DENSITY
SYSTEMS
STATE
UPT3
MECHANISM
PARTICLE
VALENCE
Аннотация: We search for marginal Fermi-liquid behavior in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron-polaron effects and other mechanisms for mass-enhancement (related to the momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find a tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case with a large mismatch between the densities of heavy and light bands in the strong coupling limit. We also find that for low temperatures and equal densities, the resistivity in a homogeneous state R(T) proportional to T-2 behaves as a Fermi-liquid in both 3D and 2D. For temperatures greater than the effective bandwidth for heavy electrons T W-h*, the coherence of the heavy component breaks down completely. The heavy particles move diffusively in the surrounding light particles. At the same time, light particles scatter on heavy particles as if on immobile (static) impurities. Under these conditions, the heavy component is marginal, while the light component is not. The resistivity approaches saturation for T W-h* in the 3D case. In 2D the resistivity has a maximum and a localization tail owing to weak-localization corrections of the Altshuler-Aronov type. This behavior of resistivity in 3D could be relevant for some uranium-based heavy-fermion compounds such as UNi2Al3 and in 2D, for some other mixed-valence compounds, possibly including layered manganites. We also consider briefly the superconductive (SC) instability in this model. The leading instability tends to p-wave pairing and is governed by an enhanced Kohn-Luttinger mechanism for SC at low electron densities. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light electrons in 2D. (C) 2011 American Institute of Physics. [doi:10.1063/1.3552118]
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E.
Заглавие : THE critical exponent of the tree lattice generating function in the eden model
Разночтения заглавия :авие SCOPUS: The critical exponent of the tree lattice generating function in the eden model
Место публикации : Theor. Math. Phys.: SPRINGER, 2010. - Vol. 165, Is. 2. - P1443-1455. - ISSN 0040-5779, DOI 10.1007/s11232-010-0120-5
Примечания : Cited References: 14
Предметные рубрики: GROWTH PARAMETER
CLUSTERS
DIMENSIONS
SYSTEMS
Ключевые слова (''Своб.индексиров.''): number of lattice trees--tree perimeter--generating function--critical exponent--hypercubic lattice--bethe lattice--eden model--bethe lattice--critical exponent--eden model--generating function--hypercubic lattice--number of lattice trees--tree perimeter
Аннотация: We consider the increase in the number of trees as their size increases in the Eden growth model on simple and face-centered hypercubic lattices in different space dimensions. We propose a first-order partial differential equation for the tree generating function, which allows relating the exponent at the critical point of this function to the perimeter of the most probable tree. We estimate tree perimeters for the lattices considered. The theoretical values of the exponents agree well with the values previously obtained by computer modeling. We thus explain the closeness of the dimension dependences of the exponents of the simple and face-centered lattices and their difference from the results in the Bethe lattice approximation.
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