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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Melnikova S. V., Misyul S. V., Voronov V. N., Aleksandrov K. S.
Заглавие : Phase-transitions in elpasolite Rb2KSCF6
Место публикации : Fiz. Tverd. Tela. - 1992. - Vol. 34, Is. 7. - P.2185-2195. - ISSN 0367-3294
Примечания : Cited References: 24
Предметные рубрики: RB2KMIIIF6 ELPASOLITES
CS2NANDCL6
SCATTERING
RB2NADYF6
CS2RBDYF6
RB2KDYF6
CRYSTAL
MODE
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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) : Bulgakov E. N., Pichugin K. N., Sadreev A. F., Streda P., Seba P.
Заглавие : Hall-like effect induced by spin-orbit interaction
Место публикации : Phys. Rev. Lett.: AMERICAN PHYSICAL SOC, 1999. - Vol. 83, Is. 2. - P376-379. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.83.376
Примечания : Cited References: 17
Предметные рубрики: BERRYS PHASE
CONDUCTANCE
SCATTERING
SPECTRUM
RINGS
Аннотация: We study the effect of spin-orbit interaction on the electron-transport properties of a cross-junction structure. It results in spin polarization of left and right outgoing electron waves. Consequently, the incoming electron wave of a certain polarization induces a voltage drop perpendicular to the direct current flow between the source and drain of the four-terminal cross structure investigated. The resulting Hall-like resistance is estimated to be of the order of 10(-3)-10(-2)h/e(2) for technologically feasible structures. The effect becomes more pronounced in the vicinity of resonances when the Hall-like resistance changes its sign as a function of the Fermi energy.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Role of zinc and nickel impurities in high-temperature superconductors
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1999. - Vol. 41, Is. 4. - P534-538. - ISSN 1063-7834, DOI 10.1134/1.1130819
Примечания : Cited References: 32
Предметные рубрики: PR2-XCEXCUO4+DELTA SINGLE-CRYSTALS
SR-CU-O
COPPER OXIDES
MAGNETIC-PROPERTIES
NI
MODEL
ZN
SUBSTITUTION
SCATTERING
SPECTRUM
Аннотация: The local changes produced in the electronic structure and their effect on the physical properties of the superconducting and normal phases when zinc and nickel are substituted for copper are examined on the basis of a multiband p-d model. It is shown that strong electronic correlations suppress the S = 1 configuration of Ni2+ and cause the superposition of the S = 1/2 and S = 0 states of nickel. The change in the density of states in p- and n-type systems is studied, and the peculiarity of Zn impurity for p- type systems and Ni impurity for n-type systems is shown. The universal dependence of the T-c on the residual resistance in lightly doped superconductors and deviations from it in optimally doped systems are discussed. (C) 1999 American Institute of Physics. [S1063-7834(99)00704-2].
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Ospishchev S. V., Aleksandrov K. S.
Заглавие : Transport properties of HTSC plus Ba(Pb, Met)O-3 composites as functions of the electrical and magnetic characteristics of nonsuperconducting components
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 5. - P.810-815. - ISSN 1063-7834, DOI 10.1134/1.1131294
Примечания : Cited References: 27
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
CURRENT-VOLTAGE CHARACTERISTICS
NORMAL-METAL LAYER
WEAK LINKS
JUNCTIONS
SCATTERING
BAPB1-XBIXO3
TRANSITION
IMPURITIES
BREAKING
Аннотация: Composites simulating a network of weak metallic links and consisting of a classic 1-2-3 HTSC and a BaPbO3 metal oxide with incorporated Sn, Ni, and Fe impurities have been prepared. Experimental resistivity, magnetic, and Mossbauer studies of the BaPb(0.9)Met(0.1)O(3) nonsuperconducting components are presented. The transport properties of the HTSC + BaPb(0.9)Met(0.1)O(3) composites have been investigated. The superconducting properties of the composites are observed to be suppressed, both when the carrier mean free path in nonsuperconducting components with tin impurities decreases, and as a result of an additional interaction of the magnetic moments of (Fe, Ni) impurities with the spins of supercurrent carriers. The experimental temperature dependences of the composite critical current are analyzed in terms of the de Gennes theory for the superconductor-normal metal-superconductor structures. (C) 2000 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the magnetic properties of weakly interacting antiferromagnetic chains with an alternating exchange interaction with spin S=1/2
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2000. - Vol. 90, Is. 1. - P194-201. - ISSN 1063-7761, DOI 10.1134/1.559075
Примечания : Cited References: 35
Предметные рубрики: PEIERLS COMPOUND CUGEO3
MAGNON DISPERSION
BI2CUO4
EXCITATIONS
RESONANCE
SYSTEMS
SCATTERING
DYNAMICS
NEUTRON
PHASE
Аннотация: An approximation dependence of the spontaneous magnetic moment at a site, sigma/sigma(0) - 1 = 0.71(6)delta(2.5(2)), and the antiferromagnet-singlet state phase boundary, J(2)/J(1) = 0.52(3)delta, are determined by the quantum Monte Carlo method in the self-consistent sublattice molecular field approximation for weakly interacting (J(2)) antiferromagnetic chains with spin S = 1/2 and alternating exchange interaction (J(1) +/- delta). The Neel temperature and a number of critical temperatures which could be related with the filling energy of two singlets (Delta S-z = 0) and one triplet (Delta S-z= 1) spin bands, each of which is split by the sublattice field (h(x,y)not equal h(z)) into two subbands, are determined on the basis of the computed correlation radii of the two- and four-spin correlation function, the squared total spin (S-z)(2) with respect to the longitudinal components, the dimerization parameter, and the correlation functions between the nearest neighbors with respect to longitudinal and transverse spin components. On the basis of the Monte Carlo calculations, the critical temperatures and possible energy gaps at the band center are determined for the antiferromagnets CuWO4 and Bi2CuO4 and for the singlet compounds (VO)(2)P2O7 and CuGeO3 , agreeing satisfactorily with existing results, and new effects are also predicted. (C) 2000 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Jorio A., Currat R., Myles DAA, McIntyre G. J., Aleksandrova I. P., Kiat J. M., Saint-Gregoire P.
Заглавие : Ferroelastic phase transition in Cs3Bi2I9: A neutron diffraction study
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2000. - Vol. 61, Is. 6. - P3857-3862. - ISSN 1098-0121, DOI 10.1103/PhysRevB.61.3857
Примечания : Cited References: 16
Предметные рубрики: CRYSTAL
SCATTERING
CS3SB2I9
Аннотация: Crystalline Cs3Bi2I9, With the P6(3)/mmc symmetry at room temperature was studied by Laue and four-circle neutron diffractometry from room temperature down to 50 K. At T-0 = 220 K the crystal undergoes a second-order proper ferroelastic phase transition to a polydomain structure with a nonprimitive monoclinic C12/m1 space group. Satellites were not found below T-0, indicating that the continuous distribution of sites observed in previous I-127 nuclear quadrupole resonance experiments is due either to an undetected incommensurate phase characterized by a very small displacement amplitude, or due to the fraction of the crystal volume occupied by domain walls. We argue that thick domain walls are expected in the present structure due to the absence of mechanical compatibility between domains.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vtyurin A. N., Bulou A., Krylov A. S., Voronov V. N.
Заглавие : Soft-mode condensation in Raman spectra of the Rb2KScF6 elpasolite
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2001. - Vol. 43, Is. 11. - P2154-2157. - ISSN 1063-7834, DOI 10.1134/1.1417197
Примечания : Cited References: 11
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
SCATTERING
Аннотация: This paper reports on the first observation of soft-mode condensation in the Raman spectra of the Rb2KScF6 elpasolite crystal below the transition points from the cubic to tetragonal and, subsequently, monoclinic phase. (C) 2001 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Voronov V. N., Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S.
Заглавие : Lattice dynamics and hydrostatic-pressure-induced phase transitions in ScF3
Место публикации : J. Exp. Theor. Phys.: American Institute of Physics, 2002. - Vol. 94, Is. 5. - P.977-984. - ISSN 1063-7761, DOI 10.1134/1.1484991
Примечания : Cited References: 20
Предметные рубрики: RAMAN-SPECTROSCOPY
CRYSTALS
SCATTERING
Аннотация: New phase transitions induced by hydrostatic pressure in a cubic (under standard conditions) ScF3 crystal are discovered by the methods of polarization microscopy and Raman scattering. The space groups R (3) over barc for Z = 2 and Pnma for Z = 4 are proposed for the high-pressure phases. A nonempirical computation of the lattice dynamics of the crystal is carried out. It is shown that, under normal pressure, the cubic phase is stable down to T = 0 K, while the application of a hydrostatic pressure gives rise to a phonon branch in the vibrational spectrum (between points R and M of the Brillouin zone) with negative values of squares of frequencies. The condensation of soft mode R-5 at the boundary point of the Brillouin zone leads to rhombohedral distortion of the cubic structure with the unit cell volume doubling. The calculated frequencies at q = 0 of the ScF3 lattice in the distorted rhombohedral phase are real-valued; the number and position of frequencies active in Raman scattering are in accord with the experimental values. (C) 2002 MAIK "Nauka/Interperiodica".
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Петров, Михаил Иванович, Balaev D. A., Gokhfel'd D. M., Шайхутдинов, Кирилл Александрович, Aleksandrov K. S.
Заглавие : Temperature evolution of the hysteresis in the current-voltage characteristic of a polycrystalline high-temperature superconductor with 1-2-3 structure
Место публикации : Phys. Solid State: American Institute of Physics, 2002. - Vol. 44, Is. 7. - P.1229-1234. - ISSN 1063-7834, DOI 10.1134/1.1494614
Примечания : Cited References: 38
Предметные рубрики: WEAK LINKS
ANDREEV REFLECTIONS
SIMPLIFIED MODEL
EXCESS CURRENT
SNS JUNCTIONS
SCATTERING
COMPOSITES
TRANSPORT
Аннотация: The temperature evolution of the current-voltage (I-U) characteristic of a contact of the break-junction type with direct conduction is investigated on a polycrystalline HTSC of the Y-Ba-Cu-O system. The experimental I-U characteristics possessing a hysteresis are correctly described in the framework of the Kummel-Nicolsky theory for an S-N-S contact (S stands for a superconductor; N, for a normal metal) in which the Andreev reflection of quasiparticles from the N-S interface is considered. It is shown that the shape of the I-U curve, as well as the existence of a hysteresis, is determined by the ratio of the number of "long" and "short" intergranular boundaries in the polycrystal under investigation. The coincidence of the calculated and experimental I-U curves made it possible to estimate the effective length of "natural" intergranular boundaries in polycrystalline HTSC materials. The estimate is obtained from the experimental temperature dependence of the critical current in the sample under investigation. (C) 2002 MAIK "Nauka/Interperiodica".
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Ospishchev S. V., Petrov M. I., Aleksandrov K. S.
Заглавие : The effect of paramagnetic impurities in normal metal on the critical current in a network of S-N-S Josephson junctions in bulk Y3/4Lu1/4Ba2Cu3O7+BaPb(1-x)Fe(x)O(3)composites
Разночтения заглавия :авие SCOPUS: The effect of paramagnetic impurities in normal metal on the critical current in a network of S-N-S Josephson junctions in bulk Y3/4Lu1/4Ba2Cu3O7 + BaPb1-xFexO3 composites
Место публикации : Supercond. Sci. Technol. - 2003. - Vol. 16, Is. 1. - P.60-64. - ISSN 0953-2048, DOI 10.1088/0953-2048/16/1/311
Примечания : Cited References: 41
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK LINKS
RESISTIVE PROPERTIES
MAGNETIC-IMPURITIES
EXCHANGE FIELD
SNS JUNCTIONS
F-S
COMPOSITES
SUPERCONDUCTOR
SCATTERING
Ключевые слова (''Своб.индексиров.''): critical currents--interfaces (materials)--josephson junction devices--paramagnetism--transport properties--non-superconducting ingredient--paramagnetic impurities--superconductor normal metal superconductor--oxide superconductors
Аннотация: Bulk Y3/4Lu1/4Ba2Cu3O7 + BaPb1-xFexO3 composites representing a model of a network of superconductor-normal metal-superconductor (SNS) Josephson junctions with paramagnetic impurities (Fe) in the N layers have been prepared. The transport properties of the composites have been studied. An exponential decay of the critical current with increasing Fe content in the non-superconducting ingredient of the composite has been observed. Such a behaviour is accounted for in terms of the de Gennes proximity effect theory.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Boehm M., Roessli B., Schefer J., Wills A. S., Ouladdiaf B., Lelievre-Berna E., Staub U., Petrakovskii G. A.
Заглавие : Complex magnetic ground state of CuB2O4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2003. - Vol. 68, Is. 2. - Ст.24405. - ISSN 1098-0121, DOI 10.1103/PhysRevB.68.024405
Примечания : Cited References: 16
Предметные рубрики: COPPER METABORATE
SCATTERING
Аннотация: The magnetic ground-state of copper metaborate CuB2O4 was investigated with unpolarized and polarized neutron scattering. A phase transition was found at T-N = 21 K to a commensurate weakly ferromagnetic state followed by a second transition at T* = 10 K to an incommensurate magnetic structure. Neutron diffraction revealed a continuously changing magnetic propagation vector below T*, and unusually asymmetric magnetic satellite reflections. Additionally, diffuse scattering is observed in the temperature range 1.5 K less than or equal to Tless than or equal to 30 K. The magnetic structure determined in both phases are shown to be consistent with results of symmetry analysis. In particular, we find that only one of the two inequivalent Cu2+ sublattice fully orders down to the lowest temperature. Our results show that the complex magnetic behavior of copper metaborate is a consequence of mutual interaction between the two Cu2+ sublattices with different ordering temperatures.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd D. M., Shaikhutdinov K. A.
Заглавие : Andreev reflection in natural grain boundaries of polycrystalline high-T-c superconductor La1.85Sr0.15CuO4
Разночтения заглавия :авие SCOPUS: Andreev reflection in natural grain boundaries of polycrystalline high-Tc superconductor La1.85Sr0.15CuO 4
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 7. - P1219-1222. - ISSN 1063-7834, DOI 10.1134/1.1594233
Примечания : Cited References: 30
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK LINKS
CHARGE-TRANSPORT
JUNCTIONS
CONDUCTIVITY
HYSTERESIS
COMPOSITES
SCATTERING
Аннотация: The temperature evolution of the current-voltage characteristic (CVC) of a "break junction" with metal-type conductivity on the polycrystalline La1.85Sr0.15CuO4 high-temperature superconductor is investigated. The CVC exhibits gap peculiarities and hysteresis, which is observed in the region of negative differential resistance. The experimental results are described well in terms of the Kummel-Gunsenheimer-Nicolsky theory for an S-N-S junction (S is a superconductor, N is a normal metal) this theory takes into account multiple Andreev reflection of quasiparticles. It is shown that the shape of the CVC and the existence and the shape of hysteresis are determined by the ratio of "long" and "short" grain boundaries in the polycrystal under investigation. (C) 2003 MAIK "Nauka / Interperiodica".
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Voronov V. N., Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S.
Заглавие : Pressure-induced phase transitions in ScF3 crystal-Raman spectra and lattice dynamics
Коллективы : Russian-CIS-Baltic-Japanese symposium on ferroelectricity
Место публикации : Ferroelectrics. - 2003. - Vol. 284. - P.205-219. - ISSN 0015-0193, DOI 10.1080/00150190390204691
Примечания : Cited References: 24
Предметные рубрики: SCATTERING
Ключевые слова (''Своб.индексиров.''): scf3--high pressure--phase transitions--raman scattering--ab initio lattice dynamics
Аннотация: New pressure-induced phases are found in normally cubic ScF3 crystal using polarizing microscopy and micro-Raman spectroscopy. Their supposed space groups are R (3) over barc, Z = 2 and Pnma, Z = 4. Using ab initio model cubic phase was shown to be stable at ambient pressure down to T = 0 K, while hydrostatic pressure brings one of the phonon branches down to negative squared frequencies. R-5 soft mode condensation results in the rhombohedric distortion of the cubic lattice with cell volume doubling. Calculated squared frequencies of the high pressure phase are positive, their number and values agree with experimental results.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M., Rumyantsev V. G.
Заглавие : Manifestations of the higher moments of the orientation distribution function of molecules in the spectral properties of an impurity nematic
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 98, Is. 6. - P1146-1151. - ISSN 1063-7761, DOI 10.1134/1.1777627
Примечания : Cited References: 15
Предметные рубрики: LIQUID-CRYSTAL
SCATTERING
PHASES
MATRIX
ORDER
DYES
Ключевые слова (''Своб.индексиров.''): absorption--band structure--impurities--molecular dynamics--polarization--spectrum analysis--distribution function--local field parameters--splitting--temperature dependence--nematic liquid crystals
Аннотация: The polarized electronic absorption spectra, orientation ordering, and the special local field features were studied for push-pull linear dye molecules with strong donor-acceptor electronic conjugation of terminal fragments in the matrix of a nematic liquid crystal. The temperature-induced inversion of the sign of the splitting of polarized impurity absorption bands was observed. This effect was shown to be caused by the statistical character of orientation ordering of impurity molecules and manifestation of the higher moments of the orientation distribution function. The dependence of local field parameters (Lorentz tensor components) of impurity molecules on their orientation ordering was established. This dependence was used to reproduce the temperature dependence of the orientation order parameter of the matrix. (C) 2004 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Aleksandrov K. S., Tressaud A., Fokina V. D.
Заглавие : Ferroelastic phase transitions in fluorides with cryolite and elpasolite structures
Место публикации : Crystallogr. Rep. - 2004. - Vol. 49, Is. 1. - P.100-107. - ISSN 1063-7745, DOI 10.1134/1.1643969
Примечания : Cited References: 43
Предметные рубрики: NUCLEAR MAGNETIC-RESONANCE
THERMODYNAMIC PROPERTIES
RB2KMIIIF6 ELPASOLITES
NEUTRON-DIFFRACTION
CRYSTALS
PEROVSKITES
DIAGRAM
SC
RB2KGAXSC1-XF6
SCATTERING
Аннотация: The ferroelastic phase transitions are investigated in several series of fluoride crystals belonging to the elpasolite and cryolite families (space group Fm (3) over barm) with the general formula A(2)BB'F-6. The influence of the size and shape of cations and anions on the entropy and the mechanism of structural distortions is discussed. (C) 2004 MAIK "Nauka/Interperiodica".
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17.

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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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneider E. I.
Заглавие : Effective Hamiltonian for HTSC cuprates taking into account electron-phonon interaction in the strong-correlation regime
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 101, Is. 5. - P844-855. - ISSN 1063-7761, DOI 10.1134/1.2149064
Примечания : Cited References: 38. - This work was supported by the Russian Foundation for Basic Research (project no. 03-02-16124), the program “Quantum Macrophysics” of the Presidium of the Russian Academy of Sciences, the Foundation in Support for Russian Science, the Foundation of Noncommercial
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
D-WAVE SUPERCONDUCTIVITY
T-C
DISPERSION
SCATTERING
OXIDES
STATE
MODEL
Ключевые слова (''Своб.индексиров.''): electron beams--electronic structure--optimization--phonons--electron correlations--hubbard x operators--spin-photon interaction--hamiltonians
Аннотация: Electron-phonon interaction is sequentially derived from a realistic p-d multiband model for the cuprates under conditions of strong electron correlations. The electronic structure is described using the representation of the Hubbard X operators in a generalized tight-binding method. Dependences of the diagonal and off-diagonal (on lattice sites) matrix elements of electron-phonon interaction on the wavevectors are found for three phonon modes, namely, breathing, apical breathing, and bending modes. The interactions of the breathing and bending modes with electrons are shown to contribute to the formation of kinks in the (0; 0)-(pi; pi) and (0; 0)-(pi; 0) directions, respectively. A low-energy t-J* model with phonons is developed; apart from electron-phonon interaction, it also includes spin-phonon interaction. The elimination of phonons gives an effective electron-electron interaction that depends on the occupation number of a multielectron term and on the carrier concentration due to strong electron correlations. (c) 2005 Pleiades Publishing, Inc.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyubutin I. S., Gavriliuk A. G., Struzhkin V. V., Ovchinnikov S. G., Kharlamova S. A., Bezmaternykh L. N., Hu M., Chow P.
Заглавие : Pressure-induced electron spin transition in the paramagnetic phase of the GdFe3(BO3)(4) Heisenberg magnet
Разночтения заглавия :авие SCOPUS: Pressure-induced electron spin transition in the paramagnetic phase of the GdFe3(BO3)4 Heisenberg magnet
Место публикации : JETP Letters. - 2006. - Vol. 84, Is. 9. - P.518-523. - ISSN 0021-3640, DOI 10.1134/S0021364006210119
Примечания : Cited References: 26
Предметные рубрики: TRIGONAL GDFE3(BO3)(4)
NUCLEAR
FEBO3
STATE
SCATTERING
COLLAPSE
Аннотация: The HS - LS spin crossover effect (high-spin - low-spin transition) induced by high pressure in the range 45-53 GPa is observed in trivalent Fe3+ ions in the paramagnetic phase of a (GdFe3)-Fe-57(BO3)(4) gadolinium iron borate crystal. This effect is studied in high-pressure diamond-anvil cells by two experimental methods using synchrotron radiation: nuclear resonant forward scattering (NFS) and Fe K-beta high-resolution x-ray emission spectroscopy (YES). The manifestation of the crossover in the paramagnetic phase, which has no order parameter to distinguish between the HS and LS states, correlates with the optical-gap jump and with the insulator-semiconductor transition in the crystal. Based on a theoretical many-electron model, an explanation of this effect at high pressures is proposed.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Pichugin K. N., Sadreev A. F., Rotter I.
Заглавие : Bound states in the continuum in open Aharonov-Bohm rings
Место публикации : JETP Letters. - 2006. - Vol. 84, Is. 8. - P.430-435. - ISSN 0021-3640, DOI 10.1134/S0021364006200057
Примечания : Cited References: 33
Предметные рубрики: WAVE-GUIDE
QUANTUM
TRANSMISSION
SCATTERING
BILLIARDS
ELECTRON
Аннотация: Using the formalism of the effective Hamiltonian, we consider bound states in a continuum (BIC). They are nonhermitian effective Hamiltonian eigenstates that have real eigenvalues. It is shown that BICs are orthogonal to open channels of the leads, i.e., disconnected from the continuum. As a result, BICs can be superposed to a transport solution with an arbitrary coefficient and exist in a propagation band. The one-dimensional Aharonov-Bohm rings that are opened by attaching single-channel leads to them allow exact consideration of BICs. BICs occur at discrete values of the energy and magnetic flux; however, it's realization strongly depends on the way to the BIC point.
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