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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gluck M., Kolovsky A. R., Korsch H. J.
Заглавие : Lifetime statistics for a Bloch particle in ac and dc fields
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 1999. - Vol. 60, Is. 1. - P247-258. - ISSN 1063-651X, DOI 10.1103/PhysRevE.60.247
Примечания : Cited References: 27
Предметные рубрики: DYNAMIC LOCALIZATION
QUANTUM
TRANSITION
SCATTERING
MATRICES
SYSTEMS
LADDER
STATES
ATOMS
LIGHT
Аннотация: We study the statistics of the Wigner delay time and resonance width for a Bloch particle in ac and de fields in the regime of quantum chaos. It is shown that after appropriate rescaling the distributions of these quantities have a universal character predicted by the random matrix theory of chaotic scattering. [s1063-651X(99)09907-9].
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gunyakov V. A., Parshin A. M., Shabanov V. F.
Заглавие : Investigation of the nematic-ferroelectric interface under a strong magnetic field
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 1998. - Vol. 105, Is. 12. - P761-765. - ISSN 0038-1098, DOI 10.1016/S0038-1098(97)10221-6
Примечания : Cited References: 14
Предметные рубрики: ANCHORING ENERGY
LIQUID-CRYSTAL
WALL INTERFACE
SURFACE
TRANSITION
Ключевые слова (''Своб.индексиров.''): ferroelectrics--liquid crystals--surfaces and interfaces--phase transitions--light absorption
Аннотация: The behaviour of methoxy benzylidene butyl aniline (MBBA) nematic liquid crystal on the;cleavage surface of triglycine sulphate under a strong magnetic field has been investigated. With the saturation regime obtained for the liquid crystal cell in fields up to 100 kOe, for the first time the possibility appears to determine not only the ordinary anchoring coefficient W-2, but the effective anchoring energy W* without any fitting procedure. Considerable difference in these parameters (two orders of magnitude) disagrees with "electrical" corrections of the Rapini-Papoular approximation. This discrepancy is connected with the surface polarization caused by spontaneous ordering of longitudinal components of MBBA molecular dipoles on interface. The form of the anisotropic interaction potential for such interfaces has to take into account polar effects in near-surface layers of the liquid crystal. (C) 1998 Elsevier Science Ltd.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pichugin K. N., Sadreev A. F.
Заглавие : Aharanov-Bohm oscillations of conductance in two-dimensional rings
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1997. - Vol. 56, Is. 15. - P9662-9673. - ISSN 0163-1829, DOI 10.1103/PhysRevB.56.9662
Примечания : Cited References: 56
Предметные рубрики: NORMAL-METAL RINGS
HALF FLUX QUANTA
MESOSCOPIC RING
MAGNETIC-FIELD
CIRCULAR BENDS
EDGE STATES
MAGNETOTRANSPORT
TRANSPORT
WIRES
TRANSITION
Аннотация: Transport properties of mesoscopic rings with applied external magnetic field are considered numerically. Rings have square and circular forms and a finite aspect ratio d/L where L is the ring size and d is the width of ring arms. The type of the Aharonov-Bohm oscillations (ABO's) of the transmission substantially depends on the number of channels participating in the electron transmission. Moreover the aspect ratio and the geometrical form of the ring are important for the ABO's. In square rings with a small aspect ratio (d/L = 1/10) the transmission displays periodic ABO's in the region of applied magnetic field defined by the inequality infinity l(B) = ((h) over bar c/eB)(1/2)greater than or equal to d, while for rings with a large aspect ratio (d/L = 1/3) only the single-channel transmission has quasiperiodical ABO's. For the circular rings with small aspect ratios the quasiperiodic ABO's are observed all over the region of the applied magnetic field while for the rings with moderate aspect ratios only the multichannel transmission displays irregular ABO's. The probability current flow patterns demonstrate fine correspondence between the transmission and the vortex structure of current distributions in the rings. For single-channel transmission, electron currents are laminar. For multichannel transport, current flow patterns display a complicated convection pattern in the form of a vortex lattice. An elementary cell of the vortex lattice consists of a few vortices and antivortices and has a size of similar to d/f, where f is the number of channels of electron transmission in the ring. Application of the flux distorts the vortex lattice enormously, partially destroying it. Correspondingly the Aharonov-Bohm oscillations of the transmission become irregular.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Balaev A. D., Vorotynov A. M.
Заглавие : Magnetic susceptibility and magnetic-field behavior of CuB(2)O(4) copper metaborate
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2000. - Vol. 42, Is. 2. - P321-325. - ISSN 1063-7834, DOI 10.1134/1.1131205
Примечания : Cited References: 10
Предметные рубрики: TRANSITION
STATE
Аннотация: An experimental study is reported regarding the temperature dependence of the magnetic susceptibility of a CuB(2)O(4) tetragonal single crystal within the 4.2-200-K range. It has been established that the magnetic susceptibility exhibits anomalies at 21 and 10 K and depends strongly on crystal orientation in the magnetic field. A study has been carried out of the field dependences of the magnetization of CuB(2)O(4) at various temperatures and crystal orientations. It is shown that for T 21 K, the crystal is in a paramagnetic state determined by Cu(2+) copper ions with an effective magnetic moment of 1.77 mu(B). Within the 10-21 K interval, the field dependence of the magnetization is typical of a weak ferromagnet with magnetic moments of the two antiferromagnetically coupled sublattices lying in the tetragonal plane of the crystal. The spontaneous weakly-ferromagnetic moment is 0.56 emu/g at 10 K. The canting angle of the sublattice magnetic moments, determined by the Dzyaloshinski-Moriya interaction, is 0.49 degrees. It is believed that below 10 K, the CuB(2)O(4) crystal retains its easy-plane magnetic structure, but with a zero spontaneous magnetic moment. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Roessli B., Schefer J., Petrakovskii G. A., Ouladdiaf B., Boehm M., Staub U., Vorotinov A. M., Bezmaternikh L. N.
Заглавие : Formation of a magnetic soliton lattice in copper metaborate
Место публикации : Phys. Rev. Lett.: AMERICAN PHYSICAL SOC, 2001. - Vol. 86, Is. 9. - P1885-1888. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.86.1885
Примечания : Cited References: 26
Предметные рубрики: SPIN-WAVES
BA2CUGE2O7
TRANSITION
ANTIFERROMAGNET
CUGEO3
PHASE
Ключевые слова (''Своб.индексиров.''): anisotropy--antiferromagnetism--ground state--magnetic moments--magnetic properties--magnetization--neutron diffraction--neutron scattering--phase transitions--solitons--thermal effects--antiferromagnetic state--copper metaborate--higher order magnetic satellites--magnetic soliton lattice--magnetic structure--copper compounds
Аннотация: The magnetic ground state of CuB2O4 is incommensurate at T = 1.8 K and undergoes a continuous phase transition to a noncollinear commensurate antiferromagnetic state at T* similar to 10 K. Close to T* higher-order magnetic satellites are observed. Coexistence of long- and short-range magnetic order is observed in both magnetic phases. This suggests that the association of the Dzyaloshinskii-Moriya interaction and anisotropy leads to the formation of a magnetic soliton lattice.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Gohfeld D. M., Popkov S. I., Saihutdinov K. A., Petrov M. I.
Заглавие : High-temperature superconductor based composites: Large magnetoresistance in weak magnetic fields
Место публикации : Tech. Phys. Lett.: AMER INST PHYSICS, 2001. - Vol. 27, Is. 11. - P952-955. - ISSN 1063-7850, DOI 10.1134/1.1424404
Примечания : Cited References: 16
Предметные рубрики: CRITICAL CURRENTS
APPLICABILITY
TRANSITION
TRANSPORT
SYSTEM
CUO
Аннотация: It was found that high-temperature superconductor (HTSC) based composites of the 1-2-3 (YBCO) + dielectric and YBCO + normal metal types exhibit large magnetoresistances in weak magnetic fields in a broad temperature range. This behavior is qualitatively explained using the concept of the irreversibility line in HTSCs and the mechanism of thermal fluctuations in the network of weak bonds of the Josephson type realized in HTSC composites. The HTSC-based composites exhibit a much higher sensitivity (as compared to that in the usual HTSC ceramics) to weak magnetic fields (below 300 Oe) at liquid-nitrogen temperatures, which is important for practical applications. (C) 2001 MAIK "Nauka /Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Existence of massive singlet excitations in an antiferromagnetic alternating chain with S=1/2
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2000. - Vol. 61, Is. 10. - P6780-6784. - ISSN 1098-0121, DOI 10.1103/PhysRevB.61.6780
Примечания : Cited References: 26
Предметные рубрики: PEIERLS COMPOUND CUGEO3
SPIN SYSTEMS
TRANSITION
Аннотация: The one-dimensional Heisenberg model with alternating antiferromagnetic bond and spin-1/2 has been studied by the Monte Carlo method. The thermodynamic characteristics, spin-spin, and four spin-correlation function have been calculated. From several maxima of the correlation radius of the four spin-correlation function and sharp slopes of the dimer order parameter, a longitudinal component of the total spin square as a function of temperature and magnetic field, the existence of two mass singlet excitation branches with Delta S-z=0 and one triplet with Delta S-z=1 is suggested. Critical temperatures and fields related to singlet filled bands have been estimated. From these results low-temperature (TT-SP) properties of spin-Peierls (SP) compounds CuGeO3 and NaV2O5 have been explained.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Petrakovskii G. A.
Заглавие : The magnetoelastic mechanism of singlet phase formation in a two-dimensional quantum antiferromagnet
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 2. - P234-247. - ISSN 1063-7761, DOI 10.1134/S106377610602004X
Примечания : Cited References: 18
Предметные рубрики: GROUND-STATE
SPIN
TRANSITION
CUGEO3
MODEL
Ключевые слова (''Своб.индексиров.''): crystal lattices--elasticity--mathematical models--oscillations--phase diagrams--phase transitions--quantum theory--two dimensional--atomic representation--magnetoelastic mechanism--quantum antiferromagnets--singlet phase formation--antiferromagnetic materials
Аннотация: A model describing the second-order phase transition with respect to the magnetoelastic coupling parameter from the anti ferromagnetic (AFM) to the singlet state in a two-dimensional quantum magnet on a square lattice is proposed. The spectrum of elementary excitations in the singlet and AFM phases is calculated using an atomic representation, and the evolution of transverse and longitudinal branches of this spectrum is studied in the vicinity of the transition point. It is established that the AFM to singlet phase transition is related to softening of the longitudinal branch of oscillations. In the singlet phase, the gap plays the role of a parameter characterizing the distance to the phase transition point. It is shown that the spectrum of transverse oscillations in the AFM phase corresponds to the Goldstone boson. Based on an analysis of the stability of the spectrum of elementary excitations, a phase diagram is constructed that determines the regions of the existence of phases with plaquette-deformed lattices.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Belozerova I. L., Gokhfeld D. M., Kashkina L. V., Kuzmin Y. I., Michel C. R., Petrov M. I., Popkov S. I., Shaikhutdinov K. A.
Заглавие : Current-voltage characteristics of a foamed Bi1.8Pb0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Разночтения заглавия :авие SCOPUS: Current-voltage characteristics of a foamed Bi1.8Pb 0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Место публикации : Phys. Solid State: SPRINGER, 2006. - Vol. 48, Is. 2. - P207-212. - ISSN 1063-7834, DOI 10.1134/S1063783406020016
Примечания : Cited References: 27
Предметные рубрики: T-C SUPERCONDUCTORS
NORMAL-PHASE
VORTEX MOTION
TRANSITION
TRANSPORT
VORTICES
Аннотация: The influence of the structure of foamed polycrystalline bismuth-based superconductors on their critical currents and current-voltage characteristics is studied. It is found that superconducting foams have a fractal structure, and the fractal dimension of the boundary between the normal and superconducting phases is estimated. The magnetic and transport properties of superconducting foams are investigated, and the current-voltage characteristics are obtained in a wide range of currents. The effect of percolation phenomena on vortex pinning in a foamed superconductor is considered. The current-voltage characteristics of the superconducting foams at the beginning of the resistive transition are found to be in good agreement with a model in which a magnetic flux is assumed to be trapped in the fractal clusters of a normal phase.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : SANDALOV I. S., HJORTSTAM O., JOHANSSON B., ERIKSSON O.
Заглавие : ORBITAL POLARIZATION IN METALLIC F-ELECTRON SYSTEMS
Разночтения заглавия :авие SCOPUS: Orbital polarization in metallic f-electron systems
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 1995. - Vol. 51, Is. 20. - P13987-14000. - ISSN 0163-1829, DOI 10.1103/PhysRevB.51.13987
Примечания : Cited References: 28
Предметные рубрики: MOTT INSULATORS
VOLUME COLLAPSE
CERIUM
LOCALIZATION
TRANSITION
PHASES
MODEL
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Potseluyko A. M., Ovchinnikov S. G., Alexandrovsky A. S., Chernov V. A., Rudenko V. V.
Заглавие : EXAFS study of Fe1-xVxBO3 system
Разночтения заглавия :авие SCOPUS: EXAFS study of Fe1 - x Vx BO3 system
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P327-329. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.119
Примечания : Cited References: 10
Предметные рубрики: MANY-ELECTRON MODEL
CALCITE STRUCTURE
BAND-STRUCTURE
FEBO3
VBO3
TRANSITION
CRBO3
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--x-ray absorption spectra--transition-metal compounds--strongly correlated electron systems--transition-metal compounds--x-ray absorption spectra--absorption--atomic force microscopy--solid solutions--transition metal compounds--x ray analysis--strongly correlated electron systems--x-ray absorption spectra--iron compounds
Аннотация: The room-temperature EXAFS measurements have been made on FeBO3 and VBO3, as well as on Fe1-xVxBO3 series with concentration x=0.13,0.3, and 0.95. The first-shell Me-O bond lengths deduced from EXAFS have shown a compositional independence. It has been found that Fe1-xVxBO3 forms solid solutions with random distribution of Fe3+ and V3+ ions. (c) 2006 Elsevier B.V. All rights reserved.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Sorokin P. B., Fedorov A. S., Fedorov D. G., Maeda Y.
Заглавие : Band-gap unification of partially Si-substituted single-wall carbon nanotubes
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2006. - Vol. 74, Is. 24. - Ст.245417. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.245417
Примечания : Cited References: 72
Предметные рубрики: SILICON-CARBIDE NANOTUBES
DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
WAVE BASIS-SET
ELECTRONIC-STRUCTURE
AB-INITIO
NANORODS
EXCITATIONS
TRANSITION
NANOWIRES
Аннотация: The atomic and electronic structure of a set of pristine single wall SiC nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was studied by the local-density approximation (LDA) plane wave band structure calculations. Consecutive substitution of carbon atoms by Si leads to a gap opening in the energetic spectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of the band gap upon the Si concentration. The same substitution for the semiconductor (10,0) single wall carbon nanotubes (SWCNT) results in a band gap minimum (0.27 eV) at similar to 25% of Si concentration. In the Si concentration region of 12-18 %, both types of nanotubes have less than 0.5 eV direct band gaps at the Gamma-Gamma point. The calculation of the chiral (8,2) SWSi0.15C0.85NT system gives a similar (0.6 eV) direct band gap. The regular distribution of Si atoms in the atomic lattice is by similar to 0.1 eV/atom energetically preferable in comparison with a random distribution. Time dependent density functional theory (DFT) calculations showed that the silicon substitution sufficiently increases (roughly by one order of magnitude) the total probability of optical transitions in the near infrared region, which is caused by the opening of the direct band gap in metallic SWCNTs, the unification of the nature and energy of the band gaps of all SWCNT species, the large values of Si3p parallel to r parallel to Si3s radial integrals and participation of Si3d states in chemical bonding in both valence and conductance bands.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Popkov S. I., Shaikhutdinov K. A., Petrov M. I.
Заглавие : Investigation of the Josephson coupling through a magnetoactive barrier (ferrimagnet, paramagnet) in Y3/4Lu1/4Ba2Cu3O7+Y-3(Al1-xFex)(5)O-12 composites
Разночтения заглавия :авие SCOPUS: Investigation of the Josephson coupling through a magnetoactive barrier (ferrimagnet, paramagnet) in Y3/4Lu1/4Ba 2Cu3O7 + Y3(Al1 - X Fe x )5O12 composites
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2046-2055. - ISSN 1063-7834, DOI 10.1134/S1063783406110023
Примечания : Cited References: 41
Предметные рубрики: S-F-S
MAGNETIC-PROPERTIES
RESISTIVE PROPERTIES
JUNCTION NETWORK
SUPERCONDUCTOR
Y3FE5-XALXO12
TRANSITION
TRANSPORT
METAL
FIELD
Аннотация: The transport properties of two-phase composites consisting of a high-temperature superconductor and a nonsuperconducting component with magnetic ordering are analyzed. These composites are considered as a network of "superconductor-magnetoactive insulator-superconductor" weak links of the Josephson type. Substituted garnets Y-3(Al1 - x Fe (x) )(5)O-12 (x = 0, ..., 1.0) are used as a magnetoactive component. The composites under investigation contain 92.5 vol % Y3/4Lu1/4Ba2Cu3O7 (the high-temperature superconductor) and 7.5 vol % Y-3(Al1 - x Fe (x) )(5)O-12 (x = 0, ..., 1.0). It is shown that an increase in the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet leads to a reduction of the Josephson coupling strength: the temperature range in which the electrical resistance of the composites is equal to zero is reduced, and the critical current density at a temperature of 4.2 K decreases exponentially. For composites in which the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet is higher than 0.1, the temperature dependence of the electrical resistance R(T) at temperatures below the transition point T-C of high-temperature superconductor crystallites has a portion in the range T-m -T-C where the resistance R(T) is independent of the transport current and the magnetic field strength. Below the temperature T-m , the dependences of the electrical resistance R(T) of the composites are nonlinear functions of the current and involve a considerable contribution from magnetoresistance. This behavior is characteristic of a network of Josephson junctions. The temperature T-m decreases with an increase in the iron content in the Y-3(Al1 - x Fe (x) )(5)O-12 garnet. The appearance of the above feature in the temperature dependences of the electrical resistance R(T) is interpreted as complete suppression of the Josephson coupling in the temperature range above T (m) due to the interaction of supercurrent carrier pairs with magnetic moments of iron atoms in the dielectric barriers separating high-temperature superconductor grains.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Piskunova N. I.
Заглавие : Anomalies in magnetoresistance and in the bulk modulus for ferromagnetics with four-spin exchange interaction on the Kondo lattice
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2006. - Vol. 18, Is. 29. - P.6859-6868. - ISSN 0953-8984, DOI 10.1088/0953-8984/18/29/023
Примечания : Cited References: 29
Предметные рубрики: MIXED-VALENCE MANGANITES
PHASE-SEPARATION
LA1-XSRXMNO3
BEHAVIOR
PECULIARITIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): elastic moduli--electric resistance--ferromagnetism--function evaluation--paramagnetism--transceivers--adiabatic approximation--kondo lattice--paramagnetic state--ring exchange--magnetoresistance
Аннотация: The temperature dependence of resistivity and the bulk modulus are calculated on the Kondo lattice, with ring exchange between localized spins, using the spin-polaron and adiabatic approximation. Peak and zero values of the bulk modulus as functions of temperature and concentration are determined below the temperature of the transition to the paramagnetic state. The effects of the nearest order between transverse spin components and a value of the ring exchange between localized spins on magnetoresistivity are estimated.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavriliuk A. G., Trojan I. A., Ovchinnikov S. G., Lyubutin I. S., Sarkisyan V. A.
Заглавие : The mechanism of suppression of strong electron correlations in FeBO3 at high pressures
Разночтения заглавия :авие SCOPUS: The mechanism of suppression of strong electron correlations in FeBO 3 at high pressures
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 99, Is. 3. - P566-573. - ISSN 1063-7761, DOI 10.1134/1.1809686
Примечания : Cited References: 18
Предметные рубрики: MAGNETIC COLLAPSE
TRANSITION
SPECTRA
ABSORPTION
STATE
Ключевые слова (''Своб.индексиров.''): crystal structure--high pressure effects--light absorption--parameter estimation--phase transitions--spectrum analysis--crystal field--electron correlations--generalized tight binding method--hybridization--iron compounds
Аннотация: The optical absorption spectra of iron borate (FeBO3) are measured at high pressures up to P = 82 GPa. A mechanism of suppression of strong electron correlations is proposed within the framework of the generalized tight binding method, which leads to the experimentally observed magnetic, electronic, and structural phase transitions. Taking into account peculiarities of the crystal structure of FeBO3 and the strong s-p hybridization of boron and oxygen, it is established that, as the distance between ions varies with increasing pressure, the crystal field parameter begins to play a decisive role in the electron transitions, while the influence of the d band broadening is negligibly small. Parameters of the theory are calculated as functions of the pressure. (C) 2004 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Shaihutdinov K. A., Popkov S. I., Gokhfeld D. M., Petrov M. I.
Заглавие : Magnetoresistive effect in bulk composites 1-2-3 YBCO+CuO and 1-2-3 YBCO+BaPb(1-x)SnxO(3) and their application as magnetic field sensors at 77 K
Разночтения заглавия :авие SCOPUS: Magnetoresistive effect in bulk composites 1-2-3 YBCO + CuO and 1-2-3 YBCO + BaPb1-xSnxO3 and their application as magnetic field sensors at 77 K
Место публикации : Supercond. Sci. Technol.: IOP PUBLISHING LTD, 2004. - Vol. 17, Is. 1. - P175-181. - ISSN 0953-2048, DOI 10.1088/0953-2048/17/1/031
Примечания : Cited References: 27
Предметные рубрики: PHASE-SLIP
SUPERCONDUCTOR
TEMPERATURE
YBA2CU3O7-DELTA
TRANSITION
Ключевые слова (''Своб.индексиров.''): ceramic materials--composite materials--critical current density (superconductivity)--high temperature operations--high temperature superconductors--lead compounds--magnetoresistance--sensors--yttrium barium copper oxides--high temperature superconductor ceramics--magnetic field sensors--magnetoresistive effect--transport current density--oxide superconductors
Аннотация: We have studied the magnetoresistive effect in bulk 1-2-3 YBCO + CuO and 1-2-3 YBCO + BaPb1-xSnxO3 composites prepared using the fast backing technique. We have found that the composites exhibit large magnetoresistance in low magnetic fields ( 100 Oe) for a broad temperature range. We have studied the experimental dependences of resistivity versus magnetic field at various transport current densities. The high-T-C superconductor (HTSC) based composites exhibit a much higher sensitivity to weak magnetic fields at liquid nitrogen temperature, compared to that for pure HTSC ceramics. This effect is attractive for practical applications and the composite materials can be used as active elements in magnetic field sensor devices.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : New Bloch period for interacting cold atoms in 1D optical lattices
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2003. - Vol. 90, Is. 21. - Ст.213002. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.90.213002
Примечания : Cited References: 19
Предметные рубрики: QUANTUM
TRANSITION
SUPERFLUID
INSULATOR
Аннотация: This paper studies Bloch oscillations of ultracold atoms in an optical lattice, in the presence of atom-atom interactions. A new, interaction-induced Bloch period is identified. Analytical results are corroborated by realistic numerical calculations.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bayukov O. A., Bykova L. E., Zhigalov V. S., Bondarenko G. N.
Заглавие : Solid-state synthesis in Ni/Fe/MgO(001) epitaxial thin films
Место публикации :. - Vol. 80, Is. 7. - P.487-490. - ISSN 0021-3640, DOI 10.1134/1.1839296
Примечания : Cited References: 34
Предметные рубрики: HIGH-TEMPERATURE SYNTHESIS
BINARY DIFFUSION COUPLES
MARTENSITIC TRANSFORMATIONS
PHASE-FORMATION
MAGNETIC-PROPERTIES
SPIN DYNAMICS
INVAR-ALLOYS
IRON
TRANSITION
NUCLEATION
Аннотация: Solid-state synthesis in Ni/Fe/MgO(001) bilayer epitaxial thin films has been studied experimentally. The phase sequence Fe/Ni -- (similar to350degreesC)Ni(3)Fe -- (similar to400degreesC)NiFe -- (similar to550degreesC)gamma(par) is formed as the annealing temperature increases. The crystal structure in the invar region consists of epitaxially intergrown single-crystal blocks consisting of the paramagnetic gamma(par) and ferromagnetic NiFe phases, which satisfy the orientation relationship [100](001)NiFe parallel to [100](001)gamma(par). It has been shown that the nucleation temperatures of the Ni(3)Fe, NiFe, and gamma(par) phases coincide with the temperatures of solid-state transformations in the Ni-Fe system. (C) 2004 MAIK "Nauka/Interperiodica".
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Dimension of mesogenic molecules as atomic clusters
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 2. - P378-389. - ISSN 1063-7834, DOI 10.1134/1.1866424
Примечания : Cited References: 19
Предметные рубрики: LIQUID-CRYSTAL CHEMISTRY
ORIENTATIONAL ORDER
TRANSITION
Аннотация: The problem regarding the mass dimension D of mesogenic molecules as atomic clusters is formulated and solved using computer simulation and analytical calculations. For a large number of compounds belonging to different chemical classes, it is shown that the cores of discotic lacunar (rodlike, lathlike) molecules forming nematic or columnar discotic (calamitic) phases have a fractional dimension 1 D-c 2 (D-c approximate to 1). The dependences of the dimension D-c on the symmetry, the conformation, and the structural-chemical features of the molecular core are determined. It is demonstrated that, in the region of side flexible chains in molecules of both types, the dimension D-ch can be either smaller or larger than unity, depending on the chain conformation. An analytical expression accounting for the results of numerical experiments is obtained for the dimension D-ch. (C) 2005 Pleiades Publishing, Inc.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavriliuk A. G., Trojan I. A., Lyubutin I. S., Ovchinnikov S. G., Sarkissian V. A.
Заглавие : High-pressure magnetic properties and P-T phase diagram of iron borate
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 4. - P688-696. - ISSN 1063-7761, DOI 10.1134/1.1926429
Примечания : Cited References: 24
Предметные рубрики: FEBO3 SINGLE-CRYSTALS
NUCLEAR-RESONANCE
BAND-STRUCTURE
TRANSITION
TEMPERATURE
SCATTERING
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--diamonds--ferromagnetic materials--high pressure effects--low temperature effects--magnetic moments--magnetic properties--magnetization--phase diagrams--powders--single crystals--synchrotron radiation--diamond anvil cells--electronic transition--iron borate--nuclear forward scattering (nfs)--iron compounds
Аннотация: The high-pressure magnetic states of iron borate (FeBO3)-Fe-57 single-crystal and powder samples have been investigated in diamond anvil cells by nuclear forward scattering (NFS) of synchrotron radiation at different temperatures. In the low-pressure (0 < P < 46 GPa) antiferromagnetic phase, an increase of the Neel temperature from 350 to 595 K induced by pressure was found. At pressures 46-49 GPa, a transition from the antiferromagnetic to a new magnetic state with a weak magnetic moment (magnetic collapse) was discovered. It is attributed to the electronic transition in Fe3+ ions from the high-spin 3d(5) (S = 5/2, (6)A(1g)) to the low-spin (S = 1/2, T-2(2g)) state (spin crossover) due to the insulator-semiconductor-type transition with extensive suppression of strong d-d electron correlations. At low temperatures, NFS spectra of the high-pressure phase indicate magnetic correlations in the low-spin system with a magnetic ordering temperature of about 50 K. A tentative magnetic P-T phase diagram of FeBO3 is proposed. An important feature of this diagram is the presence of two triple points where magnetic and paramagnetic phases of the high-spin and low-spin states coexist. © 2005 Pleiades Publishing, Inc.
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