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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : The coordinate of the singular point of generating functions of clusters in the high-temperature dynamics of spin lattice systems with axially symmetric interaction
Место публикации : Theor. Math. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2003. - Vol. 136, Is. 3. - P1297-1311. - ISSN 0040-5779, DOI 10.1023/A:1025603416535
Примечания : Cited References: 25
Предметные рубрики: CONSISTENT FLUCTUATING FIELD
NUCLEAR-DOUBLE-RESONANCE
HEISENBERG PARAMAGNET
LINE SHAPE
RELAXATION
SPECTRUM
APPROXIMATION
CRYSTALS
MOMENT
CAF2
Ключевые слова (''Своб.индексиров.''): spin dynamics--singular points--expansion over the reciprocal space dimension--expansion over the reciprocal space dimension--singular points--spin dynamics
Аннотация: We investigate generating functions for equipped trees composed of double bonds of two sorts on a hypercubic lattice of dimension d with built-in fragments. Rules for constructing these clusters are chosen to ensure the estimate for coefficients of power series in time for the longitudinal and transverse autocorrelation functions of the spin system with axially symmetric interaction. We derive a system of two equations for the tree-generating functions and an equation for the generating functions of chains leading from the root to a fragment in a tree using the Bethe approximation and under the condition that mainly bonds of one sort are taken into account. For the face-centered hypercubic lattice, we find the First terms of the 1/d expansion for the coordinate of the singular point of the generating function in both the anisotropic and the isotropic cases taking fragments in the forms of a triangle from four bonds and a four-fold bound pair into account. The obtained result is written in terms of ratios of lattice sums and is generalized to nuclear spin systems with dipole-dipole interaction. The theoretical value of the singular-point coordinate agrees well with the experimental value calculated from the tail of the absorption spectrum of the nuclear magnetic resonance in a barium fluoride monocrystal.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Golovnya A. A.
Заглавие : Effect of Spin Fluctuations on the Superconducting Phase of Hubbard Fermions in the t-t'-t"-J* Model
Коллективы :
Разночтения заглавия :авие SCOPUS: Effect of spin fluctuations on the superconducting phase of Hubbard fermions in the t-t′-t″-J*model
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 6. - P996-1008. - ISSN 1063-7761, DOI 10.1134/S1063776108120091
Примечания : Cited References: 33. - This work was supported by the Program "Quantum Macrophysics" of the Presidium of the Russian Academy of Sciences, Russian Foundation for Basic Research (project no. 06.02.16100), and Integration project no. 3.4 of the Siberian Branch of the Russian Academy of Sciences.
Предметные рубрики: SPECTRUM
Ключевые слова (''Своб.индексиров.''): electric conductivity--fermions--integral equations--spin dynamics--spin fluctuations--anomalous components--critical temperatures--electron concentrations--hubbard--hubbard operators--joint effects--large systems--nonhomogeneous equations--one-loop approximations--order parameters--renormalization--scattering process--self energies--spin-fluctuation--strongly correlated electrons--superconducting phase--system of integral equations--superconductivity
Аннотация: The effect of spin-fluctuation scattering processes on the region of the superconducting phase in strongly correlated electrons (Hubbard fermions) is investigated by the diagram technique for Hubbard operators. Modified Gor'kov equations in the form of an infinitely large system of integral equations are derived taking into account contributions of anomalous components P(0 sigma),((sigma) over bar0) of strength operator P. It is shown that spin-fluctuation scattering processes in the one-loop approximation for the t-t'-t"-J* model taking into account long-range hoppings and three-center interactions are reflected by normal (P(0 sigma), (0 sigma)) and anomalous (P(0 sigma), ((sigma) over bar0)) components of the strength operator. Three-center interactions result in different renormalizations of the kernels of the integral equations for the superconducting d phase in the expressions for the self-energy and strength operators. In this approximation for the d-type symmetry of the order parameter for the superconducting phase, the system of integral equations is reduced to a system of nonhomogeneous equations for amplitudes. The resultant dependences of critical temperature on the electron concentrations show that joint effect of long-range hoppings, three-center interactions, and spin-fluctuation processes leads to strong renormalization of the superconducting phase region.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger effect and anomalous pairing in new superconducting systems and graphene
Коллективы : Physics Department of the Russian Academy of Sciences [P.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 118, Is. 6. - P.995-1011. - ISSN 1063-7761, DOI 10.1134/S1063776114060132. - ISSN 1090-6509
Примечания : Cited References: 114. - This study was supported by the Program of the Physics Department of the Russian Academy of Sciences (project no. P.3.1) and the Russian Foundation for Basic Research (project nos. 14-02-00058 and 14-02-31237). The work of two coauthors (M. M. K. and V.A.M) was supported financially by grant no. MK-526.2013.2 of the President of the Russian Federation and the Dynasty Foundation.
Предметные рубрики: P-WAVE SUPERCONDUCTIVITY
EXTENDED HUBBARD-MODEL
NARROW ENERGY-BANDS
2D KONDO-LATTICE
FERMI GAS
REPULSIVE INTERACTIONS
ELECTRON CORRELATIONS
COOPER INSTABILITY
PHASE-DIAGRAM
SPECTRUM
Аннотация: We present a review of theoretical investigations into the Kohn-Luttinger nonphonon superconductivity mechanism in various 3D and 2D repulsive electron systems described by the Fermi-gas, Hubbard, and Shubin-Vonsovsky models. Phase diagrams of the superconducting state are considered, including regions of anomalous s-, p-, and d-wave pairing. The possibility of a strong increase in the superconducting transition temperature T c even for a low electron density is demonstrated by analyzing the spin-polarized case or the two-band situation. The Kohn-Luttinger theory explains or predicts superconductivity in various materials such as heterostructures and semimetals, superlattices and dichalcogenides, high-T c superconductors and heavy-fermion systems, layered organic superconductors, and ultracold Fermi gases in magnetic traps. This theory also describes the anomalous electron transport and peculiar polaron effects in the normal state of these systems. The theory can be useful for explaining the origin of superconductivity and orbital currents (chiral anomaly) in systems with the Dirac spectrum of electrons, including superfluid 3He-A, doped graphene, and topological superconductors.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Feher A., Yyurkin I. M., Deich L. I., Orendac M., Turyanitsa I. D.
Заглавие : The comparative-analysis of some low-frequency vibrational-state density models of the amorphous materials - applied to the as2s3 glass
Коллективы : International Conference on Low Temperature Physics
Место публикации : Physica B/ International Conference on Low Temperature Physics (20 ; 1993 ; Aug. 04-11 ; Eugene, OR). - 1994. - Vol. 194. - P.395-396. - ISSN 0921-4526, DOI 10.1016/0921-4526(94)90527-4
Примечания : Cited References: 6
Предметные рубрики: SPECTRUM
Аннотация: The specific heat from 3K to 15K and the Raman spectra were measured on the As2S3 glass. The specific heat data were fitted using two different models of the vibrational state density, i.e. the phonon-fraction model and the model of lognormal distribution of frequencies. We have shown that the excess vibrational state density which governs the specific heat behaviour gives only a little contribution to the intensity of Raman scattering in the boson peak region.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Stolyar S. V., Chekanova L. A., Vazhenina I. G.
Заглавие : Spin-Wave Resonance in One-Dimensional Magnonic Crystals by an Example of Multilayer Co-P Films
Место публикации : Phys. Solid State. - 2020. - Vol. 62, Is. 10. - P.1861-1867. - ISSN 1063-7834, DOI 10.1134/S1063783420100121. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 47
Предметные рубрики: FERROMAGNETIC-RESONANCE
SPECTRUM
MODES
INHOMOGENEITIES
Аннотация: Layered magnetic films of Co–P alloy, which are sets of laminates with certain atomic and chemical structures, have been investigated by spin-wave resonance. Coatings of two types were synthesized: a magnonic crystal (amorphous Co(P)/fcc Co(P))N and gradient Co(P) films. They exhibit two different modifications of the spin-wave resonance (SWR) spectrum. In the first case, the SWR spectrum is described as Hn(n) ~ n2 with a modification caused by the formation of the first stop band of the magnonic crystal. In the second case, the dependence of resonance fields Hn of the spin-wave modes on mode number n has the form of Hn(n) ~ n2/3. Thermal annealing leads to crystallization (amorphous alloy → fcc) and causes transformation of the layered films to the films of single-phase Co–P alloys, which is accompanied by a change in the shapes of the SWR spectra and occurrence of a “exchange kink” spectral modification.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Stolyar S. V., Chizhik M. V., Chekanova L. A.
Заглавие : Spin-Wave Resonance in Multilayer Films (One-Dimensional Magnon Crystals). Identification Rules
Место публикации : JETP Letters. - 2011. - Vol. 94, Is. 4. - P.301-305. - ISSN 0021-3640, DOI 10.1134/S0021364011160077
Примечания : Cited References: 17. - This work was supported by the Ministry of Education and Science of the Russian Federation, project no. RNP 2.1.1/3498, program "Development of Scientific Potential of Higher Schools" for 2009 and 2010 and the program "Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013. We are grateful to Prof. V. A. Ignatchenko for stimulating discussions.
Предметные рубрики: SPECTRUM
ALLOYS
Аннотация: The characteristic modification of the spectrum of the exchange spin waves has been revealed in ferromagnet/ferromagnet multilayer films with a thickness of N(d(1) + d(2)) by the spin-wave resonance method. This modification is due to the first bandgap at the wavenumber k(b) = pi/(d(1) + d(2)) of a magnon crystal, which is formed by one-dimensional modulation of the magnetization. It has been shown that the transformation of the multilayer film with thermal annealing to the film of a single-phase alloy is accompanied by the disappearance of this modification of the spectrum. DOI: 10.1134/S0021364011160077
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vazhenina I. G., Iskhakov R. S., Milyaev M. A., Naumova L. I., Rautskii M. V.
Заглавие : Spin Wave Resonance in the [(Co0.88Fe0.12)/Cu]N Synthetic Antiferromagnet
Коллективы : Ministry of Science and Higher Education of the Russian Federation [AAAA-A18-118020290104-2]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [20-42-660018]
Место публикации : Tech. Phys. Lett. - 2020. - Vol. 46, Is. 11. - P.1076-1079. - ISSN 1063-7850, DOI 10.1134/S1063785020110140. - ISSN 1090-6533(eISSN)
Примечания : Cited References: 19. - This study was carried out under a state order of the Ministry of Science and Higher Education of the Russian Federation (theme "Spin" no. AAAA-A18-118020290104-2) and supported in part by the Russian Foundation for Basic Research (project no. 20-42-660018)
Предметные рубрики: MAGNETIC-PROPERTIES
MAGNETORESISTANCE
SPECTRUM
FILMS
Аннотация: The [(Co0.88Fe0.12)/Cu]N synthetic antiferromagnet has been investigated by the spin wave resonance method over the entire range of angles of an external dc magnetic field to the film surface normal. The investigations have shown that the superlattice under study consists of two exchange-coupled magnetic subsystems, each manifested in the recorded spectra as a series of spin-wave modes. The dependence of the linear region of propagation of a standing spin-wave mode on the sample orientation in an external magnetic field has been established.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Ovchinnikov S. G.
Заглавие : Phonon and magnetic pairing mechanisms in high-temperature superconductors in the strong correlation limit
Место публикации : JETP Letters. - 2006. - Vol. 83, Is. 9. - P.394-398. - ISSN 0021-3640, DOI 10.1134/S0021364006090062
Примечания : Cited References: 22
Предметные рубрики: BAND HUBBARD-MODEL
ELECTRON
SCATTERING
SPECTRUM
Аннотация: The t-t'-t"-J* model of electrons interacting with three phonon modes (breathing, apical breathing, and buckling) is considered. The wave-vector dependence of the matrix elements of the electron-phonon interaction leads to opposite contributions to the pairing potential with the d(x2-y2) symmetry: the buckling mode facilitates electron pairing, while the breathing mode suppresses it. As a result, the critical temperature of La2-xSrxCuO4 that is associated with the magnetic mechanism is lowered when phonons are taken into account.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Vtyurin A. N., Shmygol' I. V., Goryainov S. V.
Заглавие : Phase transition in the layered perovskite CsScF4 induced by hydrostatic pressure
Место публикации : Phys. Solid State: American Institute of Physics, 1999. - Vol. 41, Is. 9. - P.1541-1543. - ISSN 1063-7834, DOI 10.1134/1.1131019
Примечания : Cited References: 9
Предметные рубрики: SPECTRUM
Аннотация: Using polarization microscopy and Raman scattering, we have discovered a new phase transition in the layered perovskite crystal CsScF4 under a hydrostatic pressure around 6 GPa. The proposed space group of the high-pressure phase is C-2h(2), Z=4. (C) 1999 American Institute of Physics. [S1063-7834(99)03109-3].
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10.

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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