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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : A study of anisotropic Heisenberg antiferromagnet with S=1/2 on a square lattice by Monte-Carlo method
Место публикации : Phys. Status Solidi B. - 1998. - Vol. 207, Is. 2. - P.491-498. - ISSN 0370-1972, DOI 10.1002/(SICI)1521-3951(199806)207:2491::AID-PSSB4913.0.CO;2-G
Примечания : Cited References: 24
Предметные рубрики: EU2CUO4
LA2CUO4
ORDER
MODEL
STATE
Аннотация: The two-dimensional (2D) Heisenberg model (J 0) with anisotropic exchange Delta = 1-J(X)/J(Z) greater than or equal to 0 and with S = 1/2 is studied by the quantum Monte-Carlo method. Energy, susceptibility, specific heat, spin-spin correlation functions, and correlation radius are calculated. The dependence of the Neel temperature T(N)/J = 2/ln(11/Delta) on the exchange anisotropy is determined. The static magnetic factor is very slowly decreased for T/J 0.4. It is assumed to realize topological excitations in the range of these temperatures. The correlation radius of the isotropic Heisenberg model is fitted by the dependence 1/xi = 2.05T(1.0(6))/exp (1.0(4)/T).The temperature behavior of the static structural magnetic factor in La(2)CuO(4) and Er(2)CuO(4) for T T(N) is in agreement with the MC calculations.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Dimerization of antiferromagnetic chain with 4-spin interaction
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 38, Is. 6. - P1868-1877. - ISSN 0367-3294
Примечания : Cited References: 30
Предметные рубрики: SPIN-1/2 HEISENBERG-ANTIFERROMAGNET
COMPETING INTERACTIONS
MONTE-CARLO
THERMODYNAMIC PROPERTIES
SYSTEMS
CUGEO3
TEMPERATURE
NEUTRON
STATE
MODEL
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Influence of spin-phonon coupling on the magnetic moment in 2D spin-1/2 antiferromagnet
Место публикации : Phys. Lett. A. - 2003. - Vol. 313, Is. 1-2. - P.122-125. - ISSN 0375-9601, DOI 10.1016/S0375-9601(03)00689-3
Примечания : Cited References: 17
Предметные рубрики: SQUARE LATTICE
EU2CUO4
MODEL
Ключевые слова (''Своб.индексиров.''): 2d heisenberg model--spin-phonon interactions--2d heisenberg model--spin-phonon interactions--ferromagnetic material--anisotropy--article--liquid--magnetism--mathematical model--monte carlo method--quantum theory--thermal conductivity--vibration
Аннотация: The ground state of two-dimensional Heisenberg spin-1/2 antiferromagnet (AF) with the spin-phonon coupling is studied by the quantum Monte Carlo method. The magnetic moment per site, mean-square vibration of ion, phase diagram of AF long range order-quantum spin. liquid are simulated. The spin-phonon coupling is estimated for R2CuO4, R = Gd, Eu. (C) 2003 Elsevier Science B.V. All rights reserved.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo analysis of the 2D Heisenberg antiferromagnet with S=1/2: the influence of exchange anisotropy
Разночтения заглавия :авие SCOPUS: Quantum Monte Carlo analysis of the 2D Heisenberg antiferromagnet with S = 1/2: The influence of exchange anisotropy
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1998. - Vol. 10, Is. 44. - P10061-10065. - ISSN 0953-8984, DOI 10.1088/0953-8984/10/44/012
Примечания : Cited References: 21
Предметные рубрики: SQUARE LATTICE
SYSTEMS
MODEL
Аннотация: The two-dimensional (2D) Heisenberg model with exchange anisotropy Delta = 1 - J(x)/J(z) (J 0) and S
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A., Miroshnichenko N. I.
Заглавие : Simulation of magnetic properties of the two-dimensional magnetic with anisotropic antiferromagnetic interactions and cluster ordering by quantum Monte Carlo
Место публикации : Phys. Lett. A: ELSEVIER SCIENCE BV, 2008. - Vol. 372, Is. 26. - P4722-4725. - ISSN 0375-9601, DOI 10.1016/j.physleta.2008.05.010
Примечания : Cited References: 12
Предметные рубрики: SPIN SYSTEM
EXCITATIONS
CU3B2O6
MODEL
Ключевые слова (''Своб.индексиров.''): anisotropic antiferromagnetic--cluster ordering--plateau of magnetization--modulated structure--exchange in cu3b2o6--anisotropic antiferromagnetic--cluster ordering--exchange in cu3b2o6--modulated structure--plateau of magnetization
Аннотация: Magnetic with anisotropic anti ferromagnetic exchange interactions and special topology of coupling in the square lattice with spins pairs ordering is studied by quantum Monte Carlo method. The antiferromagnetic order is found to be more stable as compared to spin liquid state. Exchange interactions and wave vector of structure modulation for Cu3B2O6 is estimated. Neel temperature versus strength of exchange in spin pair is calculated. Plateau and modulation of magnetic structure in field magnetization dependence is revealed. (C) 2008 Elsevier B.V. All rights reserved.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Fluctuations of orientational order in a uniaxial nematic liquid crystal with biaxial molecules and its response to an external field
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 5. - P990-1001. - ISSN 1063-7834, DOI 10.1134/1.1575350
Примечания : Cited References: 30
Предметные рубрики: PHASE-TRANSITION
SMECTIC-A
PARTICLES
SYSTEM
LANDAU
MODEL
Аннотация: Homogeneous thermal fluctuations of the orientational order parameters S and G of biaxial molecules in a uniaxial nematic liquid crystal are investigated in the framework of the molecular-statistical theory. It is demonstrated that the molecular biaxiality significantly affects the order parameters S and G, their temperature dependences in the nematic phase, the amplitude and the temperature dependence of the order parameter fluctuations in the nematic and isotropic phases, and the character of the transition from the nematic phase to the isotropic liquid phase. It is established that the fluctuations of the parameters S and G in the nematic phase are related to the temperature dependences of S and G and the susceptibilities chi(S) and chi(G) of the nematic liquid crystal to external fields, which leads to a change in the parameters S and G at a fixed director orientation. Explanations are offered for the known experimental data on the orientational ordering of biaxial molecules under the action of external fields in the isotropic phase of nematic liquid crystals. (C) 2003 MAIK "Nauka/Interperiodica".
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bobrov P. P., Mironov V. L., Repin A. V.
Заглавие : Dielectric permittivity spectra of oil-water-saturated sandy-clayey rocks of different mineralogical compositions and relaxation properties of water in these rocks
Коллективы : RFBR [12-05-00502a, 14-05-00151a]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2015. - Vol. 56, Is. 7. - P.1065-1073. - ISSN 1068-7971, DOI 10.1016/j.rgg.2015.06.007
Примечания : Cited References: 21. - This work was supported by RFBR (grant nos. 12-05-00502a and 14-05-00151a).
Предметные рубрики: MOIST SOILS
FREQUENCY
MODEL
TEMPERATURE
SALINITY
RANGE
GHZ
Ключевые слова (''Своб.индексиров.''): conductivity--dielectric permittivity--multifrequency dielectric relaxation--oil-bearing deposits--sandy-clayey rocks
Аннотация: Experimental measurements of the dielectric permittivity and equivalent conductivity of sandy-clayey samples (a mixture of river sand with bentonite or kaolin) saturated with salt-solution-diesel-fuel emulsions were performed in the frequency range from 10 kHz to 1 GHz at temperatures of 25-65 °C. It is shown that when the content of the salt solution in the saturating fluid does not exceed 10%, the dielectric permittivity in the frequency range from 1 MHz to 1 GHz depends little on the mineral composition of the sample and on the concentration of the saturating solution. When the portion of water is 33.3% or higher, increasing the concentration of the salt solution leads to an increase in the equivalent conductivity and the real part of the complex dielectric permittivity. Using the refractive model of the complex dielectric permittivity, we have estimated the dielectric properties of bound water, which depend on temperature and the type of clay (bentonite or kaolin) in the sand-clay mixture but are independent of the water saturation and the amount of clay in the sample.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Bound states in the continuum in photonic waveguides inspired by defects
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2008. - Vol. 78, Is. 7. - Ст.75105. - ISSN 1098-0121, DOI 10.1103/PhysRevB.78.075105
Примечания : Cited References: 53
Предметные рубрики: SCATTERING-THEORY
NUCLEAR REACTIONS
UNIFIED THEORY
TRANSMISSION
ELECTRON
MODEL
Аннотация: Photonic crystal with defect layer forms directed continuum for electromagnetic waves. Defect rods in the vicinity of the defect layer interact with the continuum and give rise to scattering of ingoing waves. We derive quantum-mechanical analog of the non-Hermitian Hamiltonian of the open system with complex eigenvalues, which describes a scattering of electromagnetic waves by the defect rods. In this formalism a bound state in the continuum (BIC) can be easily found by the condition that one of the complex eigenvalues becomes real for variation of dielectric constant of the defect rods. We numerically find BICs with discrete frequencies belong to the continuum for different arrangements of the defects and show that they are localized around the defects.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Current-voltage characteristics of the resonant tunnelling double-barrier structure under time-periodical perturbation
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1996. - Vol. 8, Is. 45. - P.8869-8887. - ISSN 0953-8984, DOI 10.1088/0953-8984/8/45/020
Примечания : Cited References: 38
Предметные рубрики: SEMICONDUCTOR DOUBLE-BARRIER
OSCILLATING QUANTUM-WELL
DEPENDENT TRANSPORT
INFRARED-RADIATION
TUNNELING TIMES
HETEROSTRUCTURES
TRANSMISSION
MODEL
FREQUENCIES
COHERENT
Аннотация: We consider a typical semiconductor resonant tunnelling GaAs/AlGaAs/GaAs nanostructure which forms a double-barrier potential with quasienergy levels corresponding to transition frequencies in the infrared and microwave regions. Two types of dynamical perturbation of the heterostructure in the form V-1(x, t) = V(1)x cos Omega t and V-2(t) = V-2 cos Omega t are considered. We analyse numerically a reconstruction of the electron transmission through the heterostructure and the current-voltage characteristics (IVC) under the influence of these dynamical perturbations. Both weak and strong perturbations are considered. We investigate the dependences of the transmission on the electron energy and the frequency of the external field with the main accent on the case where a frequency of the perturbation is tuned to a transition between quasienergies of the double-barrier structure. it is found that these resonant phenomena give rise to new peaks and dips in the IVC. In particular, it is shown that the dipole type of perturbation V-1(x, t) gives rise to a Rabi splitting of the transmission peaks and under certain conditions to a Rabi splining of the IVC peaks and dips. We demonstrate that dynamical perturbation may induce a direct current opposite to the direction of the applied voltage, and that this phenomenon takes the form of a sharp dip which has a resonant origin. It is observed that the dipole type of perturbation V-1(x, t) of laser radiation is more effective for tuning the IVC than the first perturbation V-2(t). Also absorption and emission of energy by an electron transmitted through the DBRTS are considered.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arbuzov A. B., Barbashov B. M., Nazmitdinov R. G., Pervushin V. N., Borowiec A., Pichugin K. N., Zakharov A. F.
Заглавие : Conformal Hamiltonian dynamics of general relativity
Место публикации : Phys. Lett. B: ELSEVIER SCIENCE BV, 2010. - Vol. 691, Is. 5. - P230-233. - ISSN 0370-2693, DOI 10.1016/j.physletb.2010.06.042
Примечания : Cited References: 30
Предметные рубрики: COSMOLOGICAL CONSTANT
UNIVERSE
GRAVITATION
SUPERNOVAE
MODEL
Ключевые слова (''Своб.индексиров.''): general relativity--cosmology--dilaton gravity--cosmology--dilaton gravity--general relativity
Аннотация: The General Relativity formulated with the aid of the spin connection coefficients is considered in the finite space geometry of similarity with the Dirac scalar dilaton. We show that the redshift evolution of the General Relativity describes the vacuum creation of the matter in the empty Universe at the electroweak epoch and the dilaton vacuum energy plays a role of the dark energy. (C) 2010 Elsevier B.V. All rights reserved.
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