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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : Tree growth parameter in the Eden model on face-centered hypercubic lattices
Место публикации : Theor. Math. Phys. - 2005. - Vol. 144, Is. 3. - P.1361-1371. - ISSN 0040-5779, DOI 10.1007/s11232-005-0165-z
Примечания : Cited References: 19
Предметные рубрики: BRANCHED POLYMERS
HIGH-TEMPERATURES
EXPANSION
CLUSTERS
SYSTEMS
TIME
Ключевые слова (''Своб.индексиров.''): eden model--number of lattice trees--monte carlo method--growth parameter--singular points of generating function--large-dimension expansion--face-centered hypercubic lattice--eden model--face-centered hypercubic lattice--growth parameter--large-dimension expansion--monte carlo method--number of lattice trees--singular points of generating function
Аннотация: In the Eden model, we investigate how the tree growth parameter depends on the space dimension d for face-centered hypercubic lattices. We find the first three terms of the 1/d-expansion for this parameter directly from the generating function without calculating the number of trees because the growth parameter is the reciprocal coordinate of the singular point of the tree generating function. The same growth parameter was calculated by computer experiment where the ratios between the numbers of trees without intersections and trees without restrictions in the dimensions 3, 4, 6, 8, and 10 were estimated by the Monte Carlo method on face-centered cubic lattices. The results of the two methods agree well. Comparing with the previously performed computer experiment for simple hypercubic lattices, we observe that the values of the singular exponents for the tree generating functions are close for two different types of lattices.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E.
Заглавие : THE critical exponent of the tree lattice generating function in the eden model
Разночтения заглавия :авие SCOPUS: The critical exponent of the tree lattice generating function in the eden model
Место публикации : Theor. Math. Phys.: SPRINGER, 2010. - Vol. 165, Is. 2. - P1443-1455. - ISSN 0040-5779, DOI 10.1007/s11232-010-0120-5
Примечания : Cited References: 14
Предметные рубрики: GROWTH PARAMETER
CLUSTERS
DIMENSIONS
SYSTEMS
Ключевые слова (''Своб.индексиров.''): number of lattice trees--tree perimeter--generating function--critical exponent--hypercubic lattice--bethe lattice--eden model--bethe lattice--critical exponent--eden model--generating function--hypercubic lattice--number of lattice trees--tree perimeter
Аннотация: We consider the increase in the number of trees as their size increases in the Eden growth model on simple and face-centered hypercubic lattices in different space dimensions. We propose a first-order partial differential equation for the tree generating function, which allows relating the exponent at the critical point of this function to the perimeter of the most probable tree. We estimate tree perimeters for the lattices considered. The theoretical values of the exponents agree well with the values previously obtained by computer modeling. We thus explain the closeness of the dimension dependences of the exponents of the simple and face-centered lattices and their difference from the results in the Bethe lattice approximation.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : On the Second Moment of the Multiquantum NMR Spectrum of a Solid
Место публикации : Russ. J. Phys. Chem. B: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 2, Is. 5. - P676-683. - ISSN 1990-7931, DOI 10.1134/S1990793108050035
Примечания : Cited References: 39
Предметные рубрики: MULTIPLE-QUANTUM NMR
DEPENDENT BEHAVIOR
MAGNETIC-MOMENTS
SPIN CLUSTERS
LINE-SHAPE
DYNAMICS
COHERENCES
SYSTEMS
CRYSTAL
GROWTH
Аннотация: New experimental data on the time dependence of an increase in the number of correlated spins under the conditions of the observation of the multiquantum NMR spectrum of a solid are processed on the basis of a microscopic theory for describing the growth of the second moment of multiquantum NMR developed by us earlier. As follows from the theory, the growth is an exponential function of time for crystals with quite diverse structures. The results are discussed on the basis of semiphenomenological models.
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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., 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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Shauro V. P., Ermilov A. S.
Заглавие : Implementation of the quantum order-finding algorithm on two qudits
Место публикации : JETP Letters. - 2008. - Vol. 87, Is. 6. - P.334-339. - ISSN 0021-3640, DOI 10.1134/S0021364008060143
Примечания : Cited References: 24
Предметные рубрики: EXPERIMENTAL REALIZATION
FOURIER-TRANSFORM
COMPUTATION
SYSTEMS
GATES
Аннотация: A quantum circuit has been proposed for the algorithm for finding the permutation order on two qudits with the number of levels d(1) and d(2). The sequence of the RF pulses for implementing the algorithm on two quadrupole nuclei I-1 = 7/2 (d(1) = 8) and I-2 = 3/2 (d(2) = 4) has been calculated and the algorithm has been numerically simulated. A method for preparing pseudopure states has been presented. A comparison with the implementation of the algorithm by NMR methods on five qubits has been performed.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Sofronova S. N.
Заглавие : The structural properties of RbMnX3 (X=F, Cl, Br) halides
Разночтения заглавия :авие SCOPUS: The structural properties of RbMnX3 (X = F, Cl, Br) halides
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 96, Is. 4. - P747-756. - ISSN 1063-7761, DOI 10.1134/1.1574547
Примечания : Cited References: 15
Предметные рубрики: POLARIZATION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): crystals--formability--hydrostatic pressure--ions--phase transitions--polarization--rubidium compounds--cubic structures--hexagonal structures--quadrupole polarizabilities--structural properties--halogen compounds
Аннотация: The results of nonempirical calculation of energies of three polytypes (cubic, two-layer hexagonal, and six-layer hexagonal) are given for RbMnX3 (X=F, Cl, Br) crystals. The calculation is performed using an ionic crystal model with regard for the deformability and the dipole and quadrupole polarizabilities of ions. The behavior of these crystals under the action of hydrostatic pressure is studied. It is demonstrated that, at normal pressure, the RbMnCl3 and RbMnBr3 crystals have a six-layer hexagonal structure. At pressures above 11 kbar, RbMnCl3 passes to a phase with a cubic structure; RbMnBr3 at pressures above 90 kbar passes to a phase with a two-layer hexagonal structure. The RbMnF3 crystal under normal conditions has a cubic structure and experiences no phase transformations under the effect of pressure. The obtained results are in satisfactory agreement with the known experimental data. (C) 2003 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zinenko V. I.
Заглавие : The effect of structural ordering on the magnetic, electronic, and optical properties of the LaPbMnSbO6 double perovskite
Коллективы : Russian Foundation for Basic Research [15-02-00340-a]; Russian Federation [NSH-924.2014.2]
Место публикации : J. Alloys Compd.: Elsevier Science, 2016. - Vol. 671. - P.184-191. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2016.02.085. - ISSN 1873-4669(eISSN)
Примечания : Cited References:32. - This work was supported by the Russian Foundation for Basic Research, project no. 15-02-00340-a and the Grant of the President of the Russian Federation for Support of Leading Scientific Schools no. NSH-924.2014.2.
Предметные рубрики: SYSTEMS
NI
CO
Ключевые слова (''Своб.индексиров.''): ab initio calculation--double perovskite--magnetic materials--optical--properties--electronic properties--magnetic properties--layer compound
Аннотация: The interplay between the magnetic, electronic, and optical properties and the cation structural ordering in the LaPbMnSbO6 double perovskite is studied using the Vienna Ab Initio Simulation Package (VASP). The layer and rock-salt cation ordering types are investigated. Both of them are of great importance. The rock-salt ordering of B-site cations is one of the most frequently met cation ordering types in double perovskites; the layer ordering of both cations, which can be considered as a heterostructure, is interesting for fundamental research and experimental synthesis. It was established that the properties of the two investigated structures are strongly different. The compound with the layered structure exhibits the behavior typical of a semimetal with the ferromagnetic configuration of magnetic moments, which is unusual for a double perovskite. The rock-salt structure behaves as an antiferromagnetic insulator. Another surprising feature of the structure with the layer ordering is the coexistence of a polar phase and the metal-type conductivity. The calculated optical characteristics of the two ordered structures are compared with the experimental dates. (C) 2016 Elsevier B.V. All rights reserved.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aronov I. E., Berman G. P., Campbell D. K., Dudiy S. V.
Заглавие : Wigner function description of ac transport through a two-dimensional quantum point contact
Разночтения заглавия :авие SCOPUS: Wigner function description of a.c. transport through a two-dimensional quantum point contact
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1997. - Vol. 9, Is. 24. - P.5089-5103. - ISSN 0953-8984, DOI 10.1088/0953-8984/9/24/009
Примечания : Cited References: 45
Предметные рубрики: QUANTIZED CONDUCTANCE
BALLISTIC-RESISTANCE
CONSTRICTION
CAPACITANCE
ADMITTANCE
ELECTRONS
SYSTEMS
FIELD
PUMP
Аннотация: We have calculated the admittance of a two-dimensional quantum point contact (QPC) using a novel variant of the Wigner distribution function (WDF) formalism. In the semiclassical approximation, a Boltzmann-like equation is derived for the partial WDF describing both propagating and non-propagating electron modes in an effective potential generated by the adiabatic QPC. We show that this quantum kinetic approach leads to the well known stepwise behaviour of the real part of the admittance (the conductance), and of the imaginary part of the admittance (the emittance), in agreement with the latest results derived by Christen and Buttiker, which is determined by the number of propagating electron modes. It is shown that the emittance is sensitive to the geometry of the QPC, and can be controlled by the gate voltage. We have established that the emittance has contributions corresponding to both quantum inductance and quantum capacitance. Stepwise oscillations in the quantum inductance are determined by the harmonic mean of the velocities for the propagating modes, whereas the quantum capacitance is a significant mesoscopic manifestation of the nonpropagating (reflecting) modes.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : The electron energy spectrum and superconducting transition temperature of strongly correlated fermions with three-center interactions
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 3. - P608-616. - ISSN 1063-7761, DOI 10.1134/1.1901772
Примечания : Cited References: 29
Предметные рубрики: T-J MODEL
BAND HUBBARD-MODEL
VALENCE BOND STATE
RANGE-ORDER
SYSTEMS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--fermions--ground state--hamiltonians--superconductivity--density of states--electron energy spectrum--strongly correlated fermions--superconducting phase--superconducting transition temperature
Аннотация: The renormalizations of the fermionic spectrum are considered within the framework of the t-J* model taking into account three-center interactions (H-(3)) and magnetic fluctuations. Self-consistent spin dynamics equations for strongly correlated fermions with three-center interactions were obtained to calculate quasi-spin correlators. A numerical self-consistent solution to a system of ten equations was obtained to show that, in the nearest-neighbor approximation, simultaneously including H-(3) and magnetic fluctuations at n n(1) (n(1) approximate to 0.72 for 2t/U = 0.25) caused qualitative changes in the structure of the energy spectrum. A new Van Hove singularity is then induced in the density of states, and an additional maximum appears in the T-c(n) concentration dependence of the temperature of the transition to the superconducting phase with order parameter symmetry of the d(x2-y2) type. (C) 2005 Pleiades Publishing, Inc.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Spin-Fluctuation Renormalization of the Temperature of a Superconducting s-Phase in Rare-Earth Intermetallides
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 4. - P679-691. - ISSN 1063-7761, DOI 10.1134/S1063776108100166
Примечания : Cited References: 34. - This study was supported in part by the Russian Foundation for Basic Research ( project no. 07-02-00226), the Department of Physic of the Russian Academy of Sciences ( within the program "Strongly Correlated Electrons in Semiconductors, Superconductors, and Magnetic Materials"), and the Siberian Branch of the Russian Academy of Sciences ( integration project no. 3.4).
Предметные рубрики: HEAVY-FERMION SUPERCONDUCTORS
PERIODIC ANDERSON MODEL
WAVE SUPERCONDUCTIVITY
PERTURBATION-THEORY
MECHANISM
VALENCE
SYSTEMS
LATTICE
STATE
Ключевые слова (''Своб.индексиров.''): differential equations--electric conductivity--green's function--numerical analysis--rare earth elements--spin dynamics--spin fluctuations--anomalous components--critical temperatures--experimental datums--infinite systems--numerical calculations--order parameters--periodic anderson models--renormalization--s-phase--skutterudite--strong electron correlations--sub systems--superconducting states--superconductivity
Аннотация: A theory of the superconducting state with s-type symmetry of the order parameter ( the transition to this state was observed in recently discovered heavy-fermion skutterudite LaFe(4)P(12)) is developed using the periodic Anderson model in the limit of strong electron correlations. Exact representations of Green's functions of the superconducting phase via the normal and anomalous components of the mass and strength operators are obtained. It is shown that an important role in the description of this superconducting phase is played by the anomalous components of the strength operator, which reflect spin-fluctuation processes in the localized subsystem. These components are calculated in the one-loop approximation using the solution of an infinite system of integral equations of self-consistency for the superconducting phase. Numerical calculations show that allowance for the process of scattering on spin fluctuations leads to renormalization of the critical temperature and provides agreement with the experimental data.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S.
Заглавие : Quantum renormalizations in anisotropic multisublattice magnets and the modification of magnetic susceptibility under irradiation
Коллективы : Russian Foundation for Basic Research [13-02-00523, 14-02-31237, 15-42-04372]
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 121, Is. 5. - P.860-877. - ISSN 1063-7761, DOI 10.1134/S1063776115110175. - ISSN 1090-6509(eISSN)
Примечания : Cited References:46. - This work was supported by the Russian Foundation for Basic Research, project nos. 13-02-00523, 14-02-31237, and 15-42-04372
Предметные рубрики: SINGLE-CHAIN MAGNETS
GLAUBER MODEL
EASY-PLANE
ARRANGEMENT
SYSTEMS
IONS
Аннотация: The dispersion equation of a strongly anisotropic one-dimensional magnet catena-[FeII(ClO4)2{FeIII(bpca)2}]ClO4 containing alternating high-spin (HS) (S = 2) and low-spin (LS) (S = 1/2) iron ions is obtained by the diagram technique for Hubbard operators. The analysis of this equation yields six branches in the excitation spectrum of this magnet. It is important that the crystal field for ions with spin S = 2 is described by the Hamiltonian of single-ion easy-plane anisotropy, whose orientation is changed by 90° when passing from one HS iron ion to another. The U(N) transformation technique in the atomic representation is applied to diagonalize a single-ion Hamiltonian with a large number of levels. It is shown that the modulation of the orientation of easy magnetization planes leads to a model of a ferrimagnet with easy-axis anisotropy and to the formation of energy spectrum with a large gap. For HS iron ions, a decrease in the mean value of the spin projection due to quantum fluctuations is calculated. The analysis of the specific features of the spectrum of elementary excitations allows one to establish a correspondence to a generalized Ising model for which the magnetic susceptibility is calculated in a wide range of temperatures by the transfer-matrix method. The introduction of a statistical ensemble that takes into account the presence of chains of different lengths and the presence of iron ions with different spins allows one to describe the experimentally observed modification of the magnetic susceptibility of the magnet under optical irradiation.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Electron spectrum and heat capacity of heavy fermions in the canted phase of antiferromagnetic intermetallides
Коллективы :
Место публикации : J. Exp. Theor. Phys. - 2010. - Vol. 110, Is. 2. - P.301-318. - ISSN 1063-7761, DOI 10.1134/S1063776110020147
Примечания : Cited References: 41. - This study was supported by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences, interdisciplinary integration project no. 53 of the Siberian Branch of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 07-02-00226).
Предметные рубрики: PERIODIC ANDERSON MODEL
PRESSURE-INDUCED SUPERCONDUCTIVITY
KONDO-LATTICE
FERROMAGNETISM
FLUCTUATIONS
COEXISTENCE
CERHIN5
SYSTEMS
DIAGRAM
CENISN
Ключевые слова (''Своб.индексиров.''): antiferromagnetic phase--antiferromagnetics--antiferromagnets--electron spectrum--electronic heat capacity--energy spectra--experimental data--external magnetic field--heat capacities--heavy fermion--low temperatures--magnetic sublattices--magnetic subsystems--sommerfeld constant--structural rearrangement--temperature dependence--antiferromagnetism--cerium--cerium compounds--fermions--magnetic fields--phase transitions--specific heat--spectroscopy--antiferromagnetic materials
Аннотация: The energy spectrum of heavy fermions in an external magnetic field is calculated for canted magnetic sublattices of antiferromagnetic intermetallides. This makes it possible to determine low-temperature features of electronic heat capacity of heavy-fermion antiferromagnets with the metal-type ground state taking into account the structural rearrangement of the magnetic subsystem. The calculated temperature dependences of the magnetization, heat capacity, and Sommerfeld constant in the vicinity of the point of transition to the antiferromagnetic phase correlate with experimental data obtained for heavy-fermion antiferromagnets PuGa3, Ce2Au2Cd, YbNiSi3, and PuPd5Al2.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kliava J., Malakhovskii A. V., Edelman I. S., Potseluyko A. M., Petrakovskaja E. A., Melnikova S.V., Zarubina T. V., Petrovskii G., Bruckental Y., Yeshurun Y.
Заглавие : Unusual magnetic transitions and nature of magnetic resonance spectra in oxide glasses containing gadolinium
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2005. - Vol. 71, Is. 10. - Ст.104406. - ISSN 1098-0121, DOI 10.1103/PhysRevB.71.104406
Примечания : Cited References: 40
Предметные рубрики: ELECTRON-PARAMAGNETIC-RESONANCE
BORATE GLASSES
IONS
BEHAVIOR
GD3+
SPECTROSCOPY
SYSTEMS
GD-3+
FIELD
SHAPE
Ключевые слова (''Своб.индексиров.''): gadolinium--glass--lanthanide--oxide--anisotropy--article--chemical structure--concentration response--electron spin resonance--energy--magnetism--molecular physics--nanoparticle--phase transition--refraction index--temperature sensitivity
Аннотация: Magnetic susceptibility, electron paramagnetic resonance (EPR), and optical properties have been studied in a glass system {20La(2)O(3)-22Al(2)O(3)-23B(2)O(3)-35(SiO2+GeO2)} with a part of La2O3 substituted by Gd2O3 in different concentrations. Positive Weiss constants have been found in the more heavily doped glasses and ascribed to clustering of Gd3+ ions. Two magnetic phase transitions at 55 and 12 K were detected and ascribed, respectively, to ferromagnetic and antiferromagnetic clusters containing Gd ions. The overall shape of the EPR spectra shows the presence of clustering at the higher Gd contents. At low temperatures the cluster-related resonance signal is altered in shape, indicating an onset of magnetic anisotropy field. This signal is convincingly fitted to superparamagnetic resonance arising from ferromagnetic nanoparticles. The clustering, depending on the Gd concentration, correlates with a significant shift to lower energies of the strong optical absorption band edge, ascribed to a charge transfer transition between Gd ions. A nonmonotonous change of refractive index with the increase of the Gd content indicates changes in the glass matrix and in Gd cluster structure.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Marienko M. S., Val'kov V. V.
Заглавие : Triplet p-Wave Superconductivity in the Low-Density Extended Hubbard Model with Coulomb Repulsion
Разночтения заглавия :авие SCOPUS: Triplet p-wave superconductivity in the low-density extended hubbard model with Coulomb repulsion
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 12. - P.725-730. - ISSN 0021-3640, DOI 10.1134/S0021364011120083
Примечания : Cited References: 42. - We acknowledge useful with A. V. Chubukov, A.S. Alexandrov, I.A. Fomin, K.I. Kugel, and V. V. Kabanov for stimulating discussions. This work was supported by the Russian Foundation for Basic Research (project nos. 11-02-00708 and 11-02-00741). M.S.M acknowledges the support of the US Department of Energy (award no. DE-FG02-08ER64623, Hofstra University Center for Condensed Matter).
Предметные рубрики: T-J MODEL
FERMI GAS
SUPERFLUID TRANSITION
PHASE-SEPARATION
SYSTEMS
TEMPERATURES
BEHAVIOR
LIQUID
POINT
STATE
Аннотация: We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb repulsion between electrons on neighboring sites in the limit of low electron density (n(el) - 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U V W (U and V are the onsite and the intersite Coulomb repulsions, respectively, and W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger superconductivity in idealized doped graphene
Коллективы : Program of the Division of Physical Sciences of the Russian Academy of Sciences [11.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Council of the President of the Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2014. - Vol. 188. - P.61-66. - ISSN 0038-1098, DOI 10.1016/j.ssc.2014.03.001. - ISSN 1879-2766
Примечания : Cited References: 31. - This work was supported by the Program of the Division of Physical Sciences of the Russian Academy of Sciences (Project 11.3.1), and the Russian Foundation for Basic Research (Projects 14-02-00058 and 14-02-31237). One of the authors (M.M.K.) acknowledges the support of the Council of the President of the Russian Federation (Project MK-526.2013.2), and the Dynasty Foundation.
Предметные рубрики: REPULSIVE INTERACTIONS
HUBBARD-MODEL
SUPERFLUIDITY
INSTABILITY
MECHANISM
DENSITY
SYSTEMS
Ключевые слова (''Своб.индексиров.''): graphene--superconductivity
Аннотация: Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter. (C) 2014 Elsevier Ltd. All rights reserved.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tanner G., Chappell D. J., Maksimov D. N.
Заглавие : Wave Intensity Distributions in Complex Structures
Коллективы : Workshop on Quantum Chaos and Localisation Phenomena
Место публикации : Acta Phys. Pol. A. - 2011. - Vol. 120, Is. 6A. - P.A172-A177. - ISSN 0587-4246
Примечания : Cited References: 19
Предметные рубрики: STATISTICAL ENERGY ANALYSIS
HIGH-FREQUENCIES
SYSTEMS
VIBRATIONS
Аннотация: The vibro-acoustic response of mechanical structures can in general be well approximated in terms of linear wave equations. Standard numerical solution methods comprise the finite or boundary element method in the low frequency regime and statistical energy analysis in the high-frequency limit. Major computational challenges are posed by the so-called mid-frequency problem - that is, composite structures where the local wavelength may vary by orders of magnitude across the components. Recently, a new approach towards determining the distribution of mechanical and acoustic wave energy in complex built-up structures improving on standard statistical energy analysis has been proposed. The technique interpolates between statistical energy analysis and ray tracing containing both these methods as limiting cases. The method has its origin in studying solutions of wave equation with an underlying chaotic ray-dynamics - often referred to as wave chaos. Within the new theory dynamical energy analysis - statistical energy analysis is identified as a low resolution ray tracing algorithm and typical statistical energy analysis assumptions can be quantified in terms of the properties of the ray dynamics. We have furthermore developed a hybrid statistical energy analysis/finite element method based on random wave model assumptions for the short-wavelength components. This makes it possible to tackle mid-frequency problems under certain constraints on the geometry of the structure. Dynamical energy analysis and statistical energy analysis/finite element method calculations for a range of multi-component model systems will be presented. The results are compared with both statistical energy analysis results and finite element method as well as boundary element method calculations. Dynamical energy analysis emerges as a numerically efficient method for calculating mean wave intensities with a high degree of spatial resolution and capturing long range correlations in the ray dynamics.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Isohatala J., Alekseev K. N., Kurki L. T., Pietilainen P.
Заглавие : Symmetry breaking in a driven and strongly damped pendulum
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 6. - Ст.66206. - ISSN 1539-3755, DOI 10.1103/PhysRevE.71.066206
Примечания : Cited References: 37
Предметные рубрики: DC VOLTAGE GENERATION
SEMICONDUCTOR SUPERLATTICES
JOSEPHSON-JUNCTIONS
BLOCH OSCILLATIONS
FORCED PENDULUM
CHAOS
FREQUENCY
SYSTEMS
RECTIFICATION
STANDARD
Ключевые слова (''Своб.индексиров.''): periodically driven pendulums--symmetry breaking--bifurcation (mathematics)--damping--dynamics--nonlinear systems--semiconductor superlattices--pendulums
Аннотация: We examine the conditions for appearance of a symmetry breaking bifurcation in damped and periodically driven pendulums in the case of strong damping. We show that symmetry breaking, unlike other nonlinear phenomena, can exist at high dissipation. We prove that symmetry breaking phases exist between phases of symmetric normal and symmetric inverted oscillations. We find that symmetry broken solutions occupy a smaller region of the pendulum's parameter space in comparison to the statements made in earlier considerations [McDonald and Plischke, Phys. Rev. B 27, 201 (1983)]. Our research on symmetry breaking in a strongly damped pendulum is relevant to an understanding of the phenomena of dynamic symmetry breaking and rectification in pure ac driven semiconductor superlattices.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseev K. N., Cannon E. H., McKinney J. C., Kusmartsev F. V., Campbell D. K.
Заглавие : Spontaneous dc current generation in a resistively shunted semiconductor superlattice driven by a terahertz field
Место публикации : Phys. Rev. Lett.: AMERICAN PHYSICAL SOC, 1998. - Vol. 80, Is. 12. - P2669-2672. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.80.2669
Примечания : Cited References: 21
Предметные рубрики: DYNAMIC LOCALIZATION
BLOCH OSCILLATIONS
ELECTRIC-FIELD
THZ-FIELD
PENDULUM
CHAOS
TIME
SUPPRESSION
SYSTEMS
Аннотация: We study a resistively shunted semiconductor superlattice subject to a high-frequency electric field. Using a balance equation approach that incorporates the influence of the electric circuit, we determine numerically a range of amplitude and frequency of the ac field for which a de bias and current are generated spontaneously and show that this region is likely accessible to current experiments. Our simulations reveal that the Bloch frequency corresponding to the spontaneous de bias is approximately an integer multiple of the ac field frequency.
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