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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) : Zobov V. E., Popov M. A.
Заглавие : The coordinate of a singular point of the time correlation functions for a heteronuclear spin system of a crystal
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 4. - P775-783. - ISSN 1063-7761, DOI 10.1134/1.1926438
Примечания : Cited References: 24
Предметные рубрики: FLUCTUATION SPECTRUM
CROSS-RELAXATION
NMR ABSORPTION
SHAPE
WINGS
LINE
Ключевые слова (''Своб.индексиров.''): correlation methods--crystal lattices--crystallography--functions--integral equations--lithium compounds--nuclear magnetic resonance--quantum theory--random processes--autocorrelation functions (acf)--dipole-dipole interactions (ddi)--heteronuclear spin systems--self-consistent fluctuating field (scff)--crystals
Аннотация: The singularities of the time autocorrelation functions (ACFs) for a heteronuclear spin system of a crystal are investigated. Exact expressions are obtained for ten moments of the spectra of ACFs in the approximation of a self-consistent fluctuating field (SCFF) with arbitrary axial symmetry. These expressions are applied to determine the coordinate of the lowest singular point of these functions on the imaginary-time axis for a spin system with a dipole-dipole interaction (DDI). The leading corrections to this coordinate due to the correlation of local fields in real crystals are calculated. These corrections are determined by lattice sums with triangles of four bonds and pairs of four bonds. Numerical values of the coordinate are obtained for a LiF crystal in a magnetic field directed along three crystallographic axes. An increase in the coordinate of the singular point, which follows from the theory and leads to a faster falloff of the wings of the ACF spectra, qualitatively agrees with experiment. © 2005 Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E.
Заглавие : Singular points of time-dependent correlation functions of spin systems on large-dimensional lattices at high temperatures
Место публикации : Theor. Math. Phys.: PLENUM PUBL CORP, 2000. - Vol. 123, Is. 1. - P511-523. - ISSN 0040-5779, DOI 10.1007/BF02551058
Примечания : Cited References: 21
Предметные рубрики: BRANCHED POLYMERS
HEISENBERG MAGNET
EXPANSION
MODELS
Аннотация: Time-dependent autocorrelation functions are investigated for the Heisenberg model with spins 1/2 on d-dimensional simple cubic lattices of large dimensions d at infinite temperature. The autocorrelation function on the imaginary time axis is interpreted as the generating function of bond trees constructed with double bonds. These trees provide the leading terms with respect to lid for the time-expansion coefficients of the autocorrelation function. The correction terms from branch intersections to the generating function in the Bethe approximation are derived for these trees. A procedure is suggested for finding the correction to the coordinate of the singular point of the generating function (i.e., to the reciprocal of the branch growth-rate parameter) from the above correction terms without calculating the number of trees. The leading correction terms of order 1/sigma(2) (where sigma = 2d - 1) are found for the coordinates of the singular points of the autocorrelation function in question and for the generating function of the trees constructed with single bonds in the Eden model.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E.
Заглавие : On the short duration limit for the correlation-functions of 2 distant spins at high-temperatures
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 99, Is. 3. - P.809-815. - ISSN 0044-4510
Примечания : Cited References: 15
Предметные рубрики: DYNAMICS
Аннотация: The first term in the expansion in powers of time is found for the correlation function of two spins separated by a large distance in the case of an anisotropic Heisenberg paramagnet.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : On the radius of convergence of series in powers of time for spin correlation functions of the Heisenberg magnet at high temperature
Место публикации : Theor. Math. Phys.: PLENUM PUBL CORP, 1997. - Vol. 112, Is. 3. - P1182-1191. - ISSN 0040-5779, DOI 10.1007/BF02583049
Примечания : Cited References: 22
Предметные рубрики: AUTO-CORRELATION FUNCTION
INFINITE-TEMPERATURE
PARAMAGNET
DYNAMICS
MODEL
Аннотация: The convergence of series in powers of time for spin autocorrelation functions of the Heisenberg magnet are investigated at infinite temperatures on lattices of different dimensions d. The calculation data available at the present time for the coefficients of these series are used to estimate the corresponding radii of convergence, whose growth with decreasing d is revealed and explained in a self-consistent approximation. To this end, a simplified nonlinear equation corresponding to this approximation is suggested and solved for the autocorrelation function of a system with an arbitrary number Z of nearest neighbors. The coefficients of the expansion in powers of time for the solution are represented in the form of trees on the Bethe lattice with the coordination number Z. A computer simulation method is applied to calculate the expansion coefficients for trees embedded in square, triangular, and simple cubic lattices under the condition that the intersection of tree branches is forbidden. It is found that the excluded volume effect that manifests itself in a decrease in these coefficients and in an increase in the coordinate and exponent of the singularity of the autocorrelation function on the imaginary time axis is intensified with decreasing lattice dimensions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : On the effect of an inhomogeneous magnetic field on high-frequency asymptotic behaviors of correlation functions of spin lattices
Место публикации : JETP Letters. - 2018. - Vol. 107, Is. 9. - P.553-557. - ISSN 0021-3640, DOI 10.1134/S002136401809014X. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 39
Предметные рубрики: HEISENBERG PARAMAGNET
SYSTEMS
TIME
RELAXATION
DYNAMICS
SPECTRA
Аннотация: Singular points of spin autocorrelation functions on the imaginary time axis, which determine the arguments of exponential high-frequency asymptotic behaviors, have been analyzed. It has been shown that randomly distributed inhomogeneous magnetic fields expand the wings of spectra of autocorrelation functions and, thereby, intensify the heating of a system subjected to variable magnetic fields, which are used to create effective Hamiltonians or at the saturation of inhomogeneously broadened EPR lines.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : On the coordinate of a singular point of time correlation functions for the system of nuclear magnetic moments of a crystal
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 1. - P78-84. - ISSN 1063-7761, DOI 10.1134/1.1600799
Примечания : Cited References: 22
Предметные рубрики: DIPOLAR FLUCTUATION SPECTRUM
FREE-INDUCTION DECAY
CROSS-RELAXATION
DOUBLE-RESONANCE
SPIN SYSTEMS
NMR-SPECTRA
LINE SHAPE
IRREVERSIBILITY
ABSORPTION
CAF2
Ключевые слова (''Своб.индексиров.''): absorption spectroscopy--barium compounds--crystallography--lattice constants--magnetic fields--nuclear magnetic resonance--absorption spectrum--dipole-dipole interaction--magnetic field directions--nuclear magnetic moments--magnetic moments
Аннотация: The hypothesis concerning the existence of singular points on the imaginary time axis for a correlation function of a system with the dipole-dipole interaction of nuclear spins of a crystal is verified. Within the framework of the self-consistent fluctuating field theory taking into account the principal corrections related to the correlation of local fields, a result for this coordinate is obtained in terms of the ratios of lattice sums. Experimental values of this coordinate are calculated from the wings of the nuclear magnetic resonance absorption spectrum of a BaF2 crystal for the magnetic field directions along the three crystallographic axes. Good agreement of the theoretical and experimental results justifies this hypothesis. (C) 2003 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : On the coordinate of a singular point of the time correlation function for a spin system on a simple hypercubic lattice at high temperatures
Место публикации : Theor. Math. Phys. - 2002. - Vol. 131, Is. 3. - P.862-872. - ISSN 0040-5779, DOI 10.1023/A:1015935809388
Примечания : Cited References: 19
Предметные рубрики: NUCLEAR-DOUBLE-RESONANCE
HEISENBERG MAGNET
DEPENDENCE
MODEL
Ключевые слова (''Своб.индексиров.''): spin dynamics--correlation functions--power series in time--frequency moments--singular points--generated functions--lattice trees--multidimensional expansion--correlation functions--frequency moments--generated functions--lattice trees--multidimensional expansion--power series in time--singular points--spin dynamics
Аннотация: Using the d(-1) expansion method (d is the space dimension), we estimate the coordinate of the time-dependent autocorrelation function singular point on the imaginary time axis for the spin 1/2 Heisenberg model on a simple hypercubic lattice at high temperatures. We represent the coefficients of the time expansion (the spectral moments) for the autocorrelation function as the sums of the weighted lattice figures in which the trees constructed from the double bonds give the leading contributions with respect to d(-1) and the same trees with the built-in squares from six bonds or diagrams with the fourfold bonds give the contribution of the next-to-leading order. We find the corrections to the coordinate of the autocorrelation function singular point that are due to the latter contributions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : On the concentration dependence of wings of spectra of spin correlation functions of diluted heisenberg paramagnets
Место публикации : JETP Letters. - 2016. - Vol. 103, Is. 11. - P.687-691. - ISSN 0021-3640, DOI 10.1134/S0021364016110138. - ISSN 1090-6487(eISSN)
Примечания : Cited References:26
Предметные рубрики: HIGH-TEMPERATURES
AUTOCORRELATION FUNCTION
SINGULAR POINT
SYSTEMS
TIME
COORDINATE
LATTICE
Аннотация: Singular points of the autocorrelation function on the imaginary time axis that is averaged over the location of spins in the magnetically dilute spin lattice with isotropic spin-spin interaction at a high temperature have been studied. For the autocorrelation function in the approximation of the self-consistent fluctuating local field, nonlinear integral equations have been proposed which reflect the separation of the inhomogeneous spin systems into close spins and other spins. The coordinates of the nearest singular points have been determined in terms of the radius of convergence of the expansion in powers of time, the coefficients of which have been calculated from recurrence equations. It has been shown that the coordinates of singular points and, consequently, the wings of the autocorrelation function spectrum at strong magnetic dilution are determined by the modulation of the local field by the nearest pairs of spins leading to its logarithmic concentration dependence.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : On the concentration dependence of the high-frequency asymptotics of spin correlation functions in a dilute Heisenberg paramagnet
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.P5.7. - P.279. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 5
Ключевые слова (''Своб.индексиров.''): disordered spin system--spin dynamics--autocorrelation function--singular points--wings of spectrum
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : Exponential Bound for the Heating Rate of Periodically Driven Spin Systems
Место публикации : J. Exp. Theor. Phys. - 2019. - Vol. 128, Is. 4. - P.641-649. - ISSN 1063-7761, DOI 10.1134/S1063776119030130. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 42
Предметные рубрики: AUTOCORRELATION FUNCTIONS
HEISENBERG PARAMAGNET
FLUCTUATION SPECTRUM
Аннотация: For the nuclear spin system of a solid in the presence of an inhomogeneous magnetic field, we have found a rigorous bound for the heating rate of the system under the action of a high-frequency magnetic field, which is applied, for example, to create effective Hamiltonians. We consider the autocorrelation function (ACF) of a spin rotating in a local field whose fluctuations are specified by a Gaussian random process. The correlation function of a random field is taken as the sum of a static inhomogeneous contribution and a time-dependent contribution expressed self-consistently via the spin ACF. The ACF singularities on the imaginary time axis whose coordinates determine the exponents of exponential asymptotics in the high-frequency domain are investigated. The dependences of the coordinates on field inhomogeneity for various approximations have been derived. The wing of the ACF spectrum in the cumulant approximation is shown to serve as a rigorous upper bound for the wing of the ACF spectrum and, consequently, for the heating rate of the system when subjected to variable magnetic fields. We have established that randomly distributed inhomogeneous magnetic fields increase the wings of the ACF spectra and, thus, speed up the system's heating.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : Decay of multispin multiquantum coherent states in the NMR of a solid
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 3. - P451-459. - ISSN 1063-7761, DOI 10.1134/S1063776111020129
Примечания : Cited References: 24
Предметные рубрики: SYSTEMS
SPECTRA
Ключевые слова (''Своб.индексиров.''): adiabatic approximations--andersons--coherent state--dynamic phenomena--experimental data--local fields--model-based--radiospectroscopy--relaxation functions--spin precession--theoretical result--two-component--coherent light
Аннотация: A model based on the Anderson adiabatic approximation, which is widely used for describing various aspects of dynamic phenomena in conventional radiospectroscopy, is proposed for describing the decay of multispin multiquantum coherent states in a solid. The coherent state relaxation function is represented by the product of two functions corresponding to spin precession in a two-component local field with a correlated and an uncorrelated component. Theoretical results of this study explain the experimental data reported in a number of publications and are in good agreement with these data.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Kucherov M. M.
Заглавие : Concentration dependence of the wings of a dipole-broadened magnetic resonance line in magnetically diluted lattices
Место публикации : J. Exp. Theor. Phys.: Maik Nauka-Interperiodica Publishing, 2017. - Vol. 124, Is. 1. - P.151-158. - ISSN 10637761 (ISSN), DOI 10.1134/S106377611615005X
Примечания : Cited References: 34
Ключевые слова (''Своб.индексиров.''): drug interactions--magnetic fields--magnetic resonance--magnetism--nonlinear equations--optical systems--autocorrelation functions--concentration dependence--high-frequency asymptotics--local field approximations--magnetic resonance line--modulation frequencies--strong static magnetic fields--time autocorrelation functions--autocorrelation
Аннотация: The singularities of the time autocorrelation functions (ACFs) of magnetically diluted spin systems with dipole–dipole interaction (DDI), which determine the high-frequency asymptotics of autocorrelation functions and the wings of a magnetic resonance line, are studied. Using the self-consistent fluctuating local field approximation, nonlinear equations are derived for autocorrelation functions averaged over the independent random arrangement of spins (magnetic atoms) in a diamagnetic lattice with different spin concentrations. The equations take into account the specificity of the dipole–dipole interaction. First, due to its axial symmetry in a strong static magnetic field, the autocorrelation functions of longitudinal and transverse spin components are described by different equations. Second, the long-range type of the dipole–dipole interaction is taken into account by separating contributions into the local field from distant and near spins. The recurrent equations are obtained for the expansion coefficients of autocorrelation functions in power series in time. From them, the numerical value of the coordinate of the nearest singularity of the autocorrelation function is found on the imaginary time axis, which is equal to the radius of convergence of these expansions. It is shown that in the strong dilution case, the logarithmic concentration dependence of the coordinate of the singularity is observed, which is caused by the presence of a cluster of near spins whose fraction is small but contribution to the modulation frequency is large. As an example a silicon crystal with different 29Si concentrations in magnetic fields directed along three crystallographic axes is considered. © 2017, Pleiades Publishing, Inc.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : ZOBOV V. E.
Заглавие : AUTOCORRELATION FUNCTIONS OF THE ANISOTROPIC HEISENBERG PARAMAGNET IN THE APPROXIMATION OF A SELF-CONSISTENT FLUCTUATING FIELD
Место публикации : Theor. Math. Phys.: PLENUM PUBL CORP, 1990. - Vol. 84, Is. 1. - P751-757. - ISSN 0040-5779, DOI 10.1007/BF01017200
Примечания : Cited References: 10
Предметные рубрики: RELAXATION
Аннотация: The method proposed earlier for investigating the dynamics of the isotropic Heisenberg paramagnet at high temperatures is generalized to the anisotropic case. A system of nonlinear integrodifferential equations relating the three autocorrelation functions of the x, y, and z components of an individual spin is obtained. A solution of the system is sought in the form of series in powers of the time and is investigated on the plane of the complex time variable. The coefficients of the series up to the tenth order for the xy model and the model with truncated dipole interaction are calculated, and the parameters of the singular points nearest the origin are determined from them.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vyunishev A. M., Arkhipkin V. G.
Заглавие : Quasi-phase-matched second-harmonic generation in nonlinear crystals with harmonic modulation of nonlinearity
Место публикации : Laser Phys. - 2020. - Vol. 30, Is. 4. - Ст.045401. - ISSN 1054660X (ISSN), DOI 10.1088/1555-6611/ab7381
Примечания : Cited References: 20
Аннотация: We propose a new type of nonlinear photonic crystal with the lattice representing a harmonic function of the propagation coordinate. This type of spatial modulation of the quadratic nonlinearity is implemented to enhance the second-harmonic generation (SHG) efficiency. The process resembles that realized in periodic nonlinear photonic crystals with rectangular nonlinearity modulation under quasi-phase-matching. Residual periodic oscillations of the second-harmonic intensity were found. Comparison of the unipolar and bipolar modulations showed that they are equivalent with regard to the oscillations. The SHG efficiency in the harmonic lattices is 1.6 times lower compared with the efficiency corresponding to the quasi-phase-matching in periodic nonlinear photonic crystals with rectangular lattices.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Kravtsov A. S.
Заглавие : Spectral representations and description of a superconducting state with S-type order parameter Delta(k)
Разночтения заглавия :авие SCOPUS: Spectral representations and description of a superconducting state with S-type order parameter Δ(k)
Место публикации : JETP Letters. - 2003. - Vol. 77, Is. 9. - P.505-509. - ISSN 0021-3640, DOI 10.1134/1.1591980
Примечания : Cited References: 11
Предметные рубрики: GREENS FUNCTIONS
MODEL
Аннотация: The inclusion of a singular contribution to the spectral intensity of the anomalous correlation function is shown to regain the sum rule and remove the unjustified forbidding of the S-symmetry order parameter in superconductors with strong correlations. For the order parameter of this symmetry, the solution to the self-consistency equation is analyzed beyond the nearest-neighbor approximation. (C) 2003 MAIK "Nauka / Interperiodica".
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Aksenov S. V.
Заглавие : Nonequilibrium Green’s functions in the atomic representation and the problem of quantum transport of electrons through systems with internal degrees of freedom
Место публикации : Theor. Math. Phys. - 2018. - Vol. 194, Is. 2. - P.236-251. - ISSN 00405779 (ISSN), DOI 10.1134/S0040577918020046
Примечания : Cited References: 14. - This research was supported by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund (Grant Nos. 16-02-00073, 16-42-243056, 16-42-242036, and 17-42-240441) and in part (S. V. A.) by the Program for Governmental Support for Young Scientists and Candidates of Science (Grant No. MK-1398.2017.2).
Ключевые слова (''Своб.индексиров.''): nonequilibrium green’s functions--keldysh contour--atomic representation--kinetic equation--inelastic scattering
Аннотация: We develop the theory of quantum transport of electrons through systems with strong correlations between fermionic and internal spin degrees of freedom. The atomic representation for the Hamiltonian of a device and nonequilibrium Green’s functions constructed using the Hubbard operators allow overcoming difficulties in the perturbation theory encountered in the traditional approach because of a larger number of bare scattering amplitudes. Representing the matrix elements of effective interactions as a superposition of terms each of which is split in matrix indices, we obtain a simple method for solving systems of very many equations for nonequilibrium Green’s functions in the atomic representation. As a result, we obtain an expression describing the electron currents in a device one of whose sites is in tunnel coupling with the left contact and the other, with the right contact. We derive closed kinetic equations for the occupation numbers under conditions where the electron flow leads to significant renormalization of them.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S.
Заглавие : Effect of intersite repulsion on the correlation functions and thermodynamics of an Ising chain with annealed magnetic disorder
Место публикации : Bull. Russ. Acad. Sci. Phys.: Allerton Press, 2016. - Vol. 80, Is. 11. - P.1335-1337. - ISSN 10628738 (ISSN), DOI 10.3103/S1062873816110290
Примечания : Cited References: 6. - This work was supported by the Russian Foundation for Basic Research, project nos. 13-02-00073, 14-02-31237, and 15-42-04372.
Ключевые слова (''Своб.индексиров.''): chains--magnetic susceptibility--temperature distribution--thermodynamics--transfer matrix method--correlation function--equilibrium behavior--equilibrium distributions--non-magnetic impurities--quantum phase transitions--repulsion parameter--temperature dependence--transfer matrix technique--phase transitions
Аннотация: An exact solution for a model describing the equilibrium behavior of an ensemble of Ising chains with nonmagnetic intersite repulsion of nearest neighbors and an equilibrium distribution of nonmagnetic impurities is obtained using the transfer matrix technique. The possibility of exciting quantum phase transitions using the intersite repulsion parameter in a system is demonstrated. Proximity to the critical points of these transitions has a substantial effect on the temperature dependence of a system’s magnetic susceptibility. © 2016, Allerton Press, Inc.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuklin A. V., Kuzubov A. A., Kovaleva E. A., Mikhaleva N. S., Tomilin F. N., Lee H., Avramov P. V.
Заглавие : Two-dimensional hexagonal CrN with promising magnetic and optical properties: A theoretical prediction
Место публикации : Nanoscale: Royal Society of Chemistry, 2017. - Vol. 9, Is. 2. - P.621-630. - ISSN 20403364 (ISSN), DOI 10.1039/c6nr07790k
Примечания : Cited References: 76. - We acknowledge the Siberian Supercomputer Center (SSCC) of SB RAS, Novosibirsk; the Institute of Computational Modeling of SB RAS, Krasnoyarsk; the Joint Supercomputer Center of RAS, Moscow; and the ICC of Novosibirsk State University for providing the computing resources. This work was supported by the government contract of the Ministry of Education and Science of the Russian Federation to Siberian Federal University (Grant No. 16.1500.2014/K). P. V. A. acknowledges the Kyungpook National University Research Fund, 2014. N. S. M. acknowledges the Russian Foundation for Basic Research (RFBR 16-32-60003 mol_a_dk).
Ключевые слова (''Своб.индексиров.''): boron nitride--calculations--energy gap--ferromagnetic materials--ferromagnetism--graphene--magnetism--metals--transition metals--transparency--dielectric functions--ferromagnetic orderings--first-principles calculation--half-metallic properties--magnetic and optical properties--optical transparency--spintronics application--transition metal dichalcogenides--optical properties
Аннотация: Half-metallic ferromagnetic materials with planar forms are promising for spintronics applications. A wide range of 2D lattices like graphene, h-BN, transition metal dichalcogenides, etc. are non-magnetic or weakly magnetic. Using first principles calculations, the existence of graphene-like hexagonal chromium nitride (h-CrN) with an almost flat atomically thin structure is predicted. We find that freestanding h-CrN has a 100% spin-polarized half-metallic nature with possible ferromagnetic ordering and a high rate of optical transparency. As a possible method for stabilization and synthesis, deposition of h-CrN on 2D MoSe2 or on MoS2 is proposed. The formation of composites retains the half-metallic properties and leads to the reduction of spin-down band gaps to 1.43 and 1.71 eV for energetically favorable h-CrN/MoSe2 and h-CrN/MoS2 configurations, respectively. Calculation of the dielectric functions of h-CrN, h-CrN/MoSe2 and h-CrN/MoS2 exhibit the high transparency of all three low-dimensional nanomaterials. The honeycomb CrN may be considered as a promising fundamental 2D material for a variety of potential applications of critical importance. © The Royal Society of Chemistry 2017.
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20.

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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