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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Mean polarizability of molecules and anisotropy of the Lorentz tensor upon a nematic-smectic a phase transition: Their behavior in a homologous series
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 5. - P.720-728. - ISSN 0036-0244, DOI 10.1134/S0036024412050044
Примечания : Cited References: 37
Предметные рубрики: CHOLESTERIC LIQUID-CRYSTALS
REFRACTIVE-INDEX DATA
A PHASE
MESOMORPHIC PROPERTIES
ORIENTATIONAL ORDER
OPTICAL ANISOTROPY
LOCAL-FIELD
POLYMORPHISM
TEMPERATURE
A-monotone
Alkyl chain
Experimental values
Homologous series
Homologues
Limiting values
Lorentz
Mesophases
Molecular core
Molecular polarizabilities
Nematic
Orientational order parameters
Polarizabilities
Polarizability density
Quadratic dependence
A-monotone
Smectic
Smectic phase
Smectic phasis
Smectic-A phasis
Ключевые слова (''Своб.индексиров.''): molecular polarizability--anisotropy--phase transition--nematic--smectic--homologues
Аннотация: Experimental values of the mean polarizability of molecules, (gamma) over bar, and components of the Lorentz tensor, L-j, in the nematic and smectic A phases are obtained for a homologous series of n-alkyl-p-(4-ethoxybenzylideneamino)-alpha-methylcinnamates. Dependences of the (gamma) over bar and L-j values on the mesophase temperature, the orientational order parameter S of molecules, and the number n in the homologous series are revealed. The quadratic dependence of (gamma) over bar (S) in the nematic and smectic phases is established that is invariant with respect to the nematic-smectic A transition. Polarizability densities of the molecular core and the alkyl chain are found from the monotone decreasing dependence (gamma) over bar (n)/v (where v is volume per one molecule) in the smectic phase. The presence (or absence) of the odd-even alternation of L-j(n) in the nematic (smectic) phase is shown. A monotone decrease in the Lorentz tensor anisotropy L with an increase in n is revealed in the smectic phase, and limiting values L-j(n - infinity) are determined.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskii A. A., Popkov S. I., Gokhfeld D. M., Semenov S. V., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Specific features in the hysteretic behavior of the magnetoresistance of granular high-temperature superconductors
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 11. - P.2155-2164. - ISSN 1063-7834, DOI 10.1134/S1063783412110030
Примечания : Cited References: 52. - This study was supported by the Russian Foundation for Basic Research within the framework of the Regional Competition SIBERIA (project no. 11-02-98007 r-sibir'_a).
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK MAGNETIC-FIELDS
CRITICAL-CURRENT DENSITY
T-C SUPERCONDUCTORS
ANGULAR-DEPENDENCE
JOSEPHSON MEDIUM
TRANSPORT-PROPERTIES
CRITICAL-STATE
YBa2Cu3O7-DELTA
COMPOSITES
Аннотация: The behavior of the hysteresis of the magnetoresistance R(H) of granular high-temperature superconductors has been investigated under the conditions where the resistive response of the subsystem of grain boundaries close to saturation. The hysteretic dependences R(H) have been measured for Y1-xPrxBa2Cu3O7 samples at x = 0.11 and 0.04 with the transition temperatures T-C approximate to 85.5 and 91.0 K, respectively. The evolution of the field width of the hysteresis R(H) has been examined by varying the measuring current. The limit of the applicability has been established for the concept of the effective field in the intergranular medium, which was previously proposed for the description of the hysteretic behavior of the magnetoresistance R(H) and thermal magnetic prehistory of the granular high-temperature superconductors. In the studied samples, the approximation of the effective field in the intergranular medium is applicable until the magnetoresistance of the subsystem of grain boundaries exceeds (90 +/- 5)% of the maximum value.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Tomilin F. N., Fedorov A. S., Tolstaya A. V.
Заглавие : Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 87, Is. 8. - P.1332-1335. - ISSN 0036-0244, DOI 10.1134/S0036024413080141
Примечания : Cited References: 25
Предметные рубрики: AB-INITIO
THIN-FILMS
NANOTUBES
ENERGY
Ключевые слова (''Своб.индексиров.''): silicon carbide monolayer--density functional theory
Аннотация: The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 ). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Sakai S., Entani S., Matsumoto Y., Naramoto, Hiroshi
Заглавие : Ab initio LC-DFT study of graphene, multilayer graphenes and graphite
Место публикации : Chem. Phys. Lett.: Elsevier Science BV, 2011. - Vol. 508, Is. 1-3. - P.86-89. - ISSN 0009-2614, DOI 10.1016/j.cplett.2011.04.016
Примечания : Cited References: 32. - This work was supported by JAEA Research fellowship (P.V.A.). P.V.A. also acknowledges JAEA ASRC and Molecular Spintronics Group for hospitality and fruitful collaboration.
Предметные рубрики: DENSITY
NANORIBBONS
PERFORMANCE
FUNCTIONALS
FULLERENE
COBALT
FILMS
Аннотация: Atomic structure of graphene, bi-, tri-, tetralayer graphenes and graphite as well was studied using ab initio HSE, LDA and PBE DFT approaches in periodic boundary conditions. Based on comparison of theoretical results with experimental data the performance of the methods was estimated. It was found that long-range corrected HSE potential is the most reliable DFT approximation to reproduce the atomic structure of weakly bound multilayer graphenes and graphite as well. (C) 2011 Elsevier B. V. All rights reserved.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Zinenko V. I.
Заглавие : First-principles calculations of ferroelectric properties in AA`BB`O6 double perovskites with different types of cation ordering
Место публикации : Phys. status solidi B. - 2013. - Vol. 250, Is. 9. - P.1888-1897. - ISSN 0370-1972, DOI 10.1002/pssb.201349084
Ключевые слова (''Своб.индексиров.''): density functional theory--double perovskites--ferroelectrics--polarization
Аннотация: First-principles calculations of lattice dynamics and polarization properties have been performed for double perovskite ABiBNbO6 (A - alkali metal Na, Rb, and B - trivalent metal Sc, Lu). Three possible types of A- and B-site cation ordering are studied: layer and columnar ordering of A-site cations with rocksalt ordering of B-site cations, and layer ordering of both cations. The ground state of all compounds is polar with a large value of polarization for all types of cation ordering. For some compounds we obtain spontaneous polarization of 0.7-1.0Cm-2 that is twice the BaTiO3 value. For RbBiScNbO6 the lowest-energy state has layer ordering of both A- and B-site cations, which is rare for compounds with double-perovskite structure.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Superconductivity in repulsive fermi-systems at low density
Коллективы : RFBR [11-02-00741]
Место публикации : J. Supercond. Nov. Magn.: SPRINGER, 2013. - Vol. 26, Is. 9. - P.2809-2815. - ISSN 1557-1939, DOI 10.1007/s10948-013-2262-9
Примечания : Cited References: 57. - The authors acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N.M. Plakida, N.V. Prokof'ev, M. M. Korovushkin, M. A. Mitskan. M. Yu. K. work was supported by RFBR grant No. 11-02-00741.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
FRACTIONAL-STATISTICS
PHASE-SEPARATION
HUBBARD-MODEL
GAS
ENHANCEMENT
MECHANISM
EXCHANGE
PARTICLES
Ключевые слова (''Своб.индексиров.''): anomalous superconductivity--p-wave and d-wave pairings--kohn-luttinger mechanism--shubin-vonsovsky--hubbard and t-j models
Аннотация: In the large variety of models such as 3D and 2D Fermi-gas model with hard-core repulsion, 3D and 2D Hubbard model, and the Shubin-Vonsovsky model, we demonstrate the possibility of triplet p-wave pairing at low electron density. We show that the critical temperature of the p-wave pairing can be strongly increased in a spin-polarized case or in a two-band situation already at low density and reach experimentally feasible values of (1-5) K. We also discuss briefly d-wave pairing and high-T-C superconductivity with T-C similar to 100 K, which arises in the 2D t-J model in the range of parameters realistic for cuprates.
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Pozdnyakov A. V.
Заглавие : Spectral properties of superlattices with anisotropic inhomogeneities. The transition from 3D to 2D disorder
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Diffusion and Defect Data Pt.B: Solid State Phenomena. - 2012. - Vol. 190. - P.597-600. - ISBN 1012-0394, DOI 10.4028/www.scientific.net/SSP.190.597. - ISBN 9783037854365
Ключевые слова (''Своб.индексиров.''): anisotropic inhomogeneities--dos--green function--superlattice--susceptibility--waves--anisotropic inhomogeneities--continuous transitions--correlation properties--density of state--dynamic susceptibility--inhomogeneities--spectral properties--wave numbers--dos--green's function--magnetic materials--magnetic susceptibility--superlattices--three dimensional--waves--anisotropy
Аннотация: Waves in superlattice (SL) contained inhomogeneities with anisotropic correlation properties are considered. The anisotropy of the correlation during the transition from 3D to 2D disorder is characterized by the parameter ? 1 = k ||/k?-1, where k || and k? are the correlation wave numbers along the axis of the SL and in the plane of the its layers, respectively (r || =k || -1 and r?=k?-1 are the correlation radii). Dependencies of both the dynamic susceptibility and density of states at the continuous transition from the isotropic three-dimensional inhomogeneities (? 1 = 0) to the twodimensional ones (? 1 = -1) have been obtained. В© (2012) Trans Tech Publications.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M.Yu., Efremov D. V., Mar'Enko M. S., Val'kov V. V.
Заглавие : Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article
Место публикации : Физ. низких температур: Физико-технический институт низких температур им. Б.И. Веркина НАН Украины, 2012. - Т. 38, Вып. 9. - С.1102-1108. - ISSN 0132-6414
Примечания : Библиогр.: 59 назв. - We acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N. M. Plakida, and N. V. Prokof'ev. M. Yu. K's work was supported by RFBR Grant No 11-02-00741-a.
Ключевые слова (''Своб.индексиров.''): 3d and 2d hubbard model--fermi-gas model--superconductivity
Аннотация: In the large variety of models such as 3D and 2D Fermi-gas model with hard-core repulsion, 3D and 2D Hubbard model, and Shubin-Vonsovsky model we demonstrate the possibility of triplet p-wave pairing at low electron density. We show that the critical temperature of the p-wave pairing can be strongly increased in a spinpolarized case or in a two-band situation already at low density and reach experimentally observable values of (1-5) K. We also discuss briefly d-wave pairing and high-T c superconductivity with T c ∼ 100 K which arises in the extended Hubbard model and in the generalized t-J model close to half-filling.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Mar'enko M. S., Val'kov V. V.
Заглавие : Kohn-Luttinger effect and anomalous pairing in repulsive Fermi-systems at low density : Review Article
Место публикации : Low Temp. Phys.: American Institute of Physics, 2012. - Vol. 38, Is. 9. - P.874-879. - ISSN 1063-777X, DOI 10.1063/1.4752091
Примечания : Cited References: 59. - We acknowledge helpful discussions with A. V. Chubukov, A. S. Alexandrov, V. V. Kabanov, K. I. Kugel, Yu. V. Kopaev, N. M. Plakida, and N. V. Prokof'ev. M. Yu. K's work was supported by RFBR Grant No 11-02-00741-a.
Предметные рубрики: T-J MODEL
SUPERFLUID TRANSITION-TEMPERATURE
2-BAND HUBBARD-MODEL
LOW ELECTRON-DENSITY
FRACTIONAL-STATISTICS
PHASE-SEPARATION
SUPERCONDUCTIVITY
GAS
ENHANCEMENT
MECHANISM
Ключевые слова (''Своб.индексиров.''): d-wave superconductivity--electron density--electron spin polarisation--high-temperature superconductors--hubbard model--superconducting transition temperature--t-j model--two-dimensional electron gas
Аннотация: We demonstrate the possibility of triplet p-wave pairing at low electron density a large number of models such as 3D and 2D Fermi-gas models with hard-core repulsion, 3D and 2D Hubbard models, and the Shubin-Vonsovsky model. The critical temperature for p-wave pairing can be considerably higher in the spin-polarized case or even in a two-band situation at low density and can reach experimentally observable values of 1–5 K. We also discuss briefly the d-wave pairing and high-Tc superconductivity with Tc ∼ 100 K which arise in the extended Hubbard model and in the generalized t-Jmodel when close to half-filling.
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10.

Вид документа : Статья из журнала
Шифр издания : Physics, Applied/C94
Автор(ы) : Korshunov M. M., Ovchinnikov S. G., Shneyder E. I., Gavrichkov V. A., Orlov Yu.S., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Cuprates, manganites and cobaltites: Multielectron approach to the band structure
Место публикации : Mod. Phys. Lett. B: WORLD SCIENTIFIC PUBL CO PTE LTD, 2012. - Vol. 26, Is. 24. - Ст.1230016. - ISSN 0217-9849, DOI 10.1142/S0217984912300165
Примечания : Cited References: 93. - We are thankful to O. K. Andersen, V. I. Anisimov, A. F. Barabanov, K. I. Kikoin, N. M. Plakida, S. Sakai, A.-M.S. Tremblay, V. V. Val'kov, and R. O. Zaitsev for useful discussions. This work was supported by the Presisium of RAS program Quantum physics of condensed matter N 20.7, Grant "Leading scientific schools of Russia" (NSh 1044-2012.2), RFBR (Grant No. 09-02-00127), Integration Grant of SBRAS-UrBRAS N 44, Grant of President of Russia MK-1683.2010.2, FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK 16.740.12.0731 and GK 16.740.11.0740), and Siberian Federal University (Theme N F-11). M.M.K. and E.I.S. acknowledges support from The Dynasty Foundation and ICFPM.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
MEAN-FIELD THEORY
DENSITY-FUNCTIONAL FORMALISM
CORRELATED ELECTRON-SYSTEMS
TRANSITION-METAL COMPOUNDS
SPIN-STATE TRANSITION
T-J MODEL
MAGNETIC-PROPERTIES
COPPER OXIDES
LaCoO3
Ключевые слова (''Своб.индексиров.''): lda plus gtb method--strongly-correlated systems--band structure
Аннотация: High-T-c superconductors with CuO2 layers, manganites La1-xSrxMnO3 and cobaltites LaCoO3 present several mysteries in their physical properties. Most of them are believed to come from the strongly-correlated nature of these materials. From the theoretical viewpoint, there are many hidden rocks in making the consistent description of the band structure and low-energy physics starting from the Fermi-liquid approach. Here, we discuss the alternative method - multielectron approach to the electronic structure calculations for the Mott insulators - called LDA + GTB (local density approximation + generalized tight-binding) method. Its origin is a straightforward generalization of the Hubbard perturbation theory in the atomic limit and the multiband p - d Hamiltonian with the parameters calculated within LDA. We briefly discuss the method and focus on its applications to cuprates, manganites and cobaltites.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Tomilin F. N., Fedorov A. S., Tolstaya A. V.
Заглавие : Calculating the energy of vacancies and adatoms in a hexagonal SiC monolayer
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 7. - P.1091-1095. - ISSN 0036-0244, DOI 10.1134/S0036024412070138
Примечания : Cited References: 21
Предметные рубрики: INITIO MOLECULAR-DYNAMICS
ELECTRONIC-PROPERTIES
ABSORPTION-SPECTRA
Ключевые слова (''Своб.индексиров.''): silicon carbide--defects--adatoms--density functional method
Аннотация: It is noted that the development of semiconductor SiC-electronics is prevented by a low quality of grown silicon carbide single crystals. It is found that structural defects of a substrate penetrating into an epitaxial layer upon subsequent homoepitaxial growth can considerably degrade a device's characteristics. We investigate the effect of the deformation of a hexagonal SiC monolayer on vacancy stability and material properties, and study the processes of silicon and carbon adatom migration over a surface of SiC.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ushakov A. V., Karpov I. V., Lepeshev A. A., Petrov M. I., Fedorov L. Y.
Заглавие : Study of magnetic flux pinning in granular YBa2Cu3O7-y / nanoZrO2 composites
Коллективы : Ministry of Education and Sciences of the Russian Federation [7.4484.2011]
Место публикации : JETP Letters. - 2014. - Vol. 99, Is. 2. - P.99-103. - ISSN 0021-3640, DOI 10.1134/S002136401402009X. - ISSN 1090-6487
Примечания : Cited References: 15. - This work was supported in part by the Ministry of Education and Sciences of the Russian Federation (project no. 7.4484.2011).
Предметные рубрики: TEMPERATURE SUPERCONDUCTING WIRE
CRITICAL-CURRENT-DENSITY
FILMS
Аннотация: IIn this work, the effect of ZrO2 nanoparticles prepared in a low-pressure arc discharge plasma on magnetic flux pinning of granular YBa2Cu3O7-y /nanoZrO2 composites has been studied. It has been shown that the ZrO2 nanoparticles do not change the superconducting transition and the microstructure of superconductors. At a temperature of 5 K, the addition of 0.5 and 1 wt % of ZrO2 nanoparticles may lead to the additional effect of magnetic flux pinning and the increase in the critical current density J c. The J c value for composites with 1 wt % is two times larger than that for the reference sample. The fishtail effect is observed for YBa2Cu3O7-y /nanoZrO2 composites at the temperatures of 20 and 50 K. The problems associated with the additional effect of magnetic flux pinning of granular YBa2Cu3O7-y /nanoZrO2 composites and the appearance of the fishtail effect have been discussed.
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13.

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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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Gokhfeld D. M., Popkov S. I., Shaikhutdinov K. A., Klinkova L. A., Zherikhina L. N., Tsvokhrebov A. M.
Заглавие : Increase in the magnetization loop width in the Ba0.6K0.4BiO3 superconductor: Possible manifestation of phase separation
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 118, Is. 1. - P.104-110. - ISSN 1063-7761, DOI 10.1134/S1063776114010038. - ISSN 1090-6509
Примечания : Cited References: 39
Предметные рубрики: (K,BA)BIO3 SINGLE-CRYSTALS
II SUPERCONDUCTORS
BISMUTH-OXIDE
PEAK
DENSITY
TC
Аннотация: The magnetization of Ba0.6K0.4BiO3 samples in fields up to 90 kOe in the temperature range from 2 to 30 K is investigated. It is shown that the observed increase in the width of the magnetization loop can be explained by a decrease in the phase nonuniformity upon an increase in the magnetic field. The asymmetric hysteretic dependence of magnetization with the secondary peak was successfully described by the extended critical state model taking into account the phase separation in the superconductor.
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15.

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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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Tikhonova L. V., Fedorov A. S.
Заглавие : Ab initio investigation of a new boron nitride allotrope
Коллективы : Russian Foundation for Basic Research [12-02-00640]
Место публикации : Phys. Status Solidi B. - 2014. - Vol. 251, Is. 6. - P.1282-1285. - ISSN 0370-1972, DOI 10.1002/pssb.201350389. - ISSN 1521-3951
Примечания : Cited References: 31. - We acknowledge support of the Russian Foundation for Basic Research through Grant No. 12-02-00640. Also, we thank the Institute of Computer Modeling (Siberian Division, Russian Academy of Sciences, Krasnoyarsk), the Joint Supercomputer Center of the Russian Academy of Sciences (Moscow), the computer cluster "Chebyshev" of the Moscow State University (Moscow), and the supercomputer of the Institute of Space and Information Technologies of the Siberian Federal University for providing an opportunity to use their computers for performing all calculations.
Предметные рубрики: AUGMENTED-WAVE METHOD
MOLECULAR-DYNAMICS
TRANSITION
METALS
Ключевые слова (''Своб.индексиров.''): boron nitride--computational materials science--density functional theory--elastic properties--superhard materials
Аннотация: A new allotropic superhard and superdense structure of sp3-bonded boron nitride (hP3-BN) is proposed. Geometric electronic, elastic, and optical properties of the structure are investigated by density functional theory generalized gradient approximation (DFT-GGA) calculations. It is shown that the structure is an insulator with a band gap of 5.06 eV; is density is 5.03% higher than that of cubic boron nitride (c-BN) and its bulk modulus is 2.25% higher than that of c BN. The calculated hP3-BN refractive index in the range 200-800 nm is significantly higher than the indexes of diamond and all known carbon allotropes, expect for the analogous carbon h-P3 structure, and it has a large optical dispersion. In the range above 800 nm the refractive index changes from 2.60 to 2.35. (C) WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Shaikhutdinov K. A., Aleksandrov K. S.
Заглавие : Superconductor-semiconductor-superconductor junction network in bulk polycrystalline composites Y3/4Lu1/4Ba2Cu3O7 + Cu1-xLixO
Место публикации : Superconductor Science and Technology. - 2001. - Vol. 14, Is. 9. - P.798-805. - ISSN 0953-2048, DOI 10.1088/0953-2048/14/9/333
Ключевые слова (''Своб.индексиров.''): critical current density (superconductivity)--josephson junction devices--polycrystalline materials--superconductivity--thermal effects--transport properties--superconductor junction networks--semiconductor junctions
Аннотация: Bulk Y3/4Lu1/4Ba2Cu3O7 + Cu1-xLixO composites with x = 0, 0.003 and 0.06 and varied volume content of Cu1-xLixO have been prepared. Analysis of the transport properties of the composites has shown that they can be represented as a network of superconductor-semiconductor-superconductor (S-Sm-S) weak links. The dependence of the critical current density on the normal resistance for the composites studied shows a behaviour similar to that for single Josephson junctions. The experimental temperature dependences of the critical current are qualitatively described in terms of a theory of S-Sm-S junctions that takes into account the Andreev reflection of carriers from the S-Sm and Sm-S interfaces.
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18.

Вид документа :
Шифр издания :
Автор(ы) : Петров, Михаил Иванович, Balaev D. A., Ospishchev S. V., Шайхутдинов, Кирилл Александрович, Khrustalev B. P., Aleksandrov K. S.
Заглавие : Critical currents in bulk Y3/4Lu1/4Ba2Cu3O7 + BaPbO3 composites
Место публикации : Physics Letters, Section A: General, Atomic and Solid State Physics. - 1997. - Vol. 237, Is. 1-2. - P.85-89
Предметные рубрики: HIGH-TC-SUPERCONDUCTORS
WEAK LINKS
JUNCTIONS
Ключевые слова (''Своб.индексиров.''): bulk composites--critical current density--network of weak s-n-s links--ybacuo + bapbo3--ybacuo+bapbo3 bulk composites--network of weak s-n-s links--critical current density
Аннотация: Bulk composites Y3/4Lu1/4Ba2Cu3O7 + BaPbO3 with BaPbO3 volume content of 0-60% have been prepared. Temperature dependences of resistance and critical current density Jc(T) are presented. The best agreement of experimental Jc(T) with theory has been reached for the Gunsenheimer-Schussler-Kummel consideration of superconductor-normal metal-superconductor (S-N-S) junctions in the "clean" limit. В© 1997 Elsevier Science B.V.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Shaikhutdinov K. A., Khrustalev B. P., Aleksandrov K. S.
Заглавие : Transport properties of composites high temperature superconductor + semiconductor with different carrier concentration
Место публикации : Physica C-Superconductivity and its Applications. - 1997. - Vol. 282, Is. PART 4. - P.2449-2450. - ISSN 0921-4534
Ключевые слова (''Своб.индексиров.''): carrier concentration--critical current density (superconductivity)--high temperature superconductors--semiconductor materials--thermal effects--transport properties--superconductor semiconductor superconductor junctions--composite materials
Аннотация: Composites HTSC + semiconductor with different carrier concentrations were prepared as a model of Josephson type contacts. Experimental temperature dependences of the critical current density Jc(T) in the composites are presented. The best congruence of experiment with theory was reached for the Schussler-Kummel consideration of Andreev scattering in S-Sm-S (S-superconductor, Sm-semiconductor) junctions.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : An extended critical state model: Asymmetric magnetization loops and field dependence of the critical current of superconductors
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 56, Is. 12. - P.2380-2386. - ISSN 1063-7834, DOI 10.1134/S1063783414120129. - ISSN 1090-6460
Примечания : Cited References: 37
Предметные рубрики: CRITICAL-CURRENT DENSITY
HIGH-TEMPERATURE SUPERCONDUCTORS
II SUPERCONDUCTORS
SURFACE-BARRIER
MGB2
TRANSPORT
MOTION
J(C)
PEAK
Аннотация: An extended critical state model has been developed. The model has considered the equilibrium magnetization of a surface layer and the magnetization of the central region of a superconducting sample. The magnetic flux distributions in the sample have been calculated. An analytical dependence of the critical current density on the magnetic field with different behaviors in strong and weak fields has been proposed. A relation of the asymmetry of the magnetization loops and the critical current density to the sample size has been established. The model is applicable to the parameterization of magnetization loops of single-crystal and polycrystalline superconductors.
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