Библиотека института физики им. Л.В. Киренского СО РАН

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slobodchikov, Anatoly A., Nekrasov, Igor A., Begunovich L. V., Makarov I. A., Korshunov M. M., Ovchinnikov S. G.
Заглавие : Electronic structure and minimal models for flat and corrugated CuO monolayers: An ab initio study
Место публикации : Materials. - 2023. - Vol. 16, Is. 2. - Ст.658. - ISSN 1996-1944 (ISSN), DOI 10.3390/ma16020658
Примечания : Cited References: 24. - This research was in part funded by the Russian Science Foundation grant number 23-22-00372
Аннотация: CuO atomic thin monolayer (mlCuO) was synthesized recently. Interest in the mlCuO is based on its close relation to CuO2 layers in typical high temperature cuprate superconductors. Here, we present the calculation of the band structure, the density of states and the Fermi surface of the flat mlCuO as well as the corrugated mlCuO within the density functional theory (DFT) in the generalized gradient approximation (GGA). In the flat mlCuO, the Cu-3dx2−y2 band crosses the Fermi level, while the Cu-3dxz,yz hybridized band is located just below it. The corrugation leads to a significant shift of the Cu-3dxz,yz hybridized band down in energy and a degeneracy lifting for the Cu-3dx2−y2 bands. Corrugated mlCuO is more energetically favorable than the flat one. In addition, we compared the electronic structure of the considered CuO monolayers with bulk CuO systems. We also investigated the influence of a crystal lattice strain (which might occur on some interfaces) on the electronic structure of both mlCuO and determined the critical strains of topological Lifshitz transitions. Finally, we proposed a number of different minimal models for the flat and the corrugated mlCuO using projections onto different Wannier functions basis sets and obtained the corresponding Hamiltonian matrix elements in a real space.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Nikolaev S. V., Korshunov M. M., Ovchinnikov S. G.
Заглавие : One- and two-particle correlation functions in the cluster perturbation theory for cuprates
Место публикации : Materials. - 2023. - Vol. 16, Is. 13. - Ст.4640. - ISSN 19961944 (eISSN), DOI 10.3390/ma16134640
Примечания : Cited References: 63. - V.I.K. and S.V.N. acknowledge support from the Krasnoyarsk Regional Science Foundation and Russian Science Foundation, grant no. 22-22-20007We acknowledge useful discussions with E.I. Shneyder
Аннотация: The physics of high-Tc superconducting cuprates is obscured by the effect of strong electronic correlations. One way to overcome this problem is to seek an exact solution at least within a small cluster and expand it to the whole crystal. Such an approach is at the heart of cluster perturbation theory (CPT). Here, we developed CPT for the dynamic spin and charge susceptibilities (spin-CPT and charge-CPT), with the correlation effects explicitly taken into account by the exact diagonalization. We applied spin-CPT and charge-CPT to the effective two-band Hubbard model for the cuprates obtained from the three-band Emery model and calculated one- and two-particle correlation functions, namely, a spectral function and spin and charge susceptibilities. The doping dependence of the spin susceptibility was studied within spin-CPT and CPT-RPA, that is, the CPT generalization of the random phase approximation (RPA). In the underdoped region, both our methods resulted in the signatures of the upper branch of the spin excitation dispersion with the lowest excitation energy at the (π,π) wave vector and no presence of low-energy incommensurate excitations. In the high doping region, both methods produced a low energy response at four incommensurate wave vectors in qualitative agreement with the results of the inelastic neutron scattering experiments on overdoped cuprates.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimov D. N., Aksenov S. V., Kolovsky A. R.
Заглавие : Non-Markovian master equation for quantum transport of fermionic carriers
Колич.характеристики :16 с
Место публикации : J. Phys. Condens. Matter. - 2023. - Vol. 36, Is. 4. - Ст.045301. - ISSN 09538984 (ISSN), DOI 10.1088/1361-648X/ad0351. - ISSN 1361648X (eISSN)
Примечания : Cited References: 42. - We acknowledge financial support from Russian Science Foundation through Grant No. 19-12-00167
Аннотация: We propose a simple, yet feasible, model for quantum transport of fermionic carriers across tight-binding chain connecting two reservoirs maintained at arbitrary temperatures and chemical potentials. The model allows for elementary derivation of the master equation for the reduced single particle density matrix in a closed form in both Markov and Born approximations. In the Markov approximation the master equation is solved analytically, whereas in the Born approximation the problem is reduced to an algebraic equation for the single particle density matrix in the Redfield form. The non-Markovian equation is shown to lead to resonant transport similar to Landauer's conductance. It is shown that in the deep non-Markovian regime the transport current can be matched with that obtained by the non-equilibrium Green's function method.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova L. T., Molokeev M. S., Galiakhmetova N. A., Denisov V. M., Vasil'ev G. V.
Заглавие : Synthesis, crystal structure, and thermal properties of substituted titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12
Коллективы : [FSRZ-2020-0013]
Место публикации : Phys. Solid State. - 2021. - Vol. 63. Is. 8. - P.1159-1164. - ISSN 1063-7834, DOI 10.1134/S1063783421080084. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 39. - This study was carried out in part within the state assignment for the Siberian Federal University, project no. FSRZ-2020-0013
Предметные рубрики: BI4-XRXTI3O12 R-X
PHASE-EQUILIBRIA
HEAT-CAPACITY
ND
BI4TI3O12
PR
Аннотация: Titanates Bi2Pr2Ti3O12 and Bi2Nd2Ti3O12 have been obtained by the solid-phase synthesis using sequential annealing of the Bi2O3, Nd2O3, Pr6O11, and TiO2 stoichiometric mixtures in air at temperatures of 1003–1323 K. Their crystal structure has been established by X-ray diffractometry and the high-temperature heat capacity has been determined by differential scanning calorimetry. Based on the experimental Cp = f(T) data, the main thermodynamic functions have been calculated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V.
Заглавие : Retrieving soil moisture profiles based on multifrequency polarimetric radar backscattering observations. Theoretical case study
Место публикации : Int. J. Remote Sens. - 2021. - Vol. 42, Is. 2. - P.506-519. - ISSN 01431161 (ISSN), DOI 10.1080/01431161.2020.1809743
Примечания : Cited References: 46. - This work was supported by the Russian Foundation for Basic Research (grant No. 18-05-00405) in part of the sensing depth investigation and retrieving soil moisture in the L-band, a technique for measuring moisture profiles at two frequencies of 435 MHz and 5.4 GHz was created in part of SB RAS project No. 0356-2019-0004
Аннотация: In this theoretical work, a dual-frequency polarimetric method is proposed for measuring moisture profiles in the topsoil up to 0.30 m thick. A case of measuring soil moisture profiles, which monotonically changes with depth, during 37 days after irrigation is considered. Original values of backscattering coefficients are calculated by the Oh model and by the small perturbation method at frequencies of 5.4 GHz and 435 MHz, respectively. In these calculations, we used measured moisture profiles and spectroscopic refractive mixing dielectric model of non-saline mineral soil with a clay fraction of 9.1%. Soil moisture profiles are retrieved by solving the inverse problem, the cost function of which is constructed based on the co- and cross-polarized ratios, calculated at two frequencies for the measured and modelled soil moisture profiles. An exponential function is used as a modelled soil moisture profile. It is shown that the standard deviation between the retrieved and measured soil moisture values in the surface layer 0.30 m thick appears to be ≤0.02 m3 m−3 (theoretical limit), and the determination coefficient is 0.881. The study shows a promising path towards developing multi-frequency radar systems for remote sensing of soil moisture profiles using satellites-based and unmanned aerial vehicles air-based platforms.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova L. T., Molokeev M. S., Chumilina L. G., Ryabov V. V., Denisov V. M.
Заглавие : Heat capacity and thermodynamic functions of GdGaTi2O7 in the temperature range of 320-1000 K
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 4. - P.534-537. - ISSN 1063-7834, DOI 10.1134/S1063783421040065. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 17
Аннотация: Titanate GdGaTi2O7 has been obtained from the initial oxides Gd2O3, Ga2O3, and TiO2 by the solid-state synthesis via annealing in air at temperatures of 1273 and 1573 K. The crystal structure of the titanate has been refined by X-ray diffraction. The high-temperature (320–1000 K) heat capacity of the compound has been measured by differential scanning calorimetry. Based on the experimental dependence Cp = f(T), the main thermodynamic functions of the titanate have been calculated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova L. T., Molokeev M. S., Ryabov V. V., Kargin Y. F., Chumilina L. G., Denisov V. M.
Заглавие : Crystal structure and thermodynamic properties of titanate ErGaTi2O7
Место публикации : Russ. J. Inorg. Chem. - 2021. - Vol. 66, Is. 4. - P.532-537. - ISSN 00360236 (ISSN), DOI 10.1134/S0036023621040082
Примечания : Cited References: 29
Аннотация: Erbium gallium titanate was prepared by solid-phase synthesis via the sequential calcination of precursor oxides in an air atmosphere at 1273 and 1573 K. The crystal structure of ErGaTi2O7 was characterized by full-profile analysis for the X-ray diffraction pattern of the synthesized powder sample as follows: space group Pcnb, a = 9.77326(15) Å, b = 13.5170(2) Å, c = 7.33189(11) Å, V = 918.58(3) Å3, ρ = 6.10 g/cm3. The high-temperature heat capacity of erbium gallium titanate was measured by differential scanning calorimetry within a temperature range of 320–1000 K. Based on these data, the basic thermodynamic functions of ErGaTi2O7 were calculated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Denisova L. T., Molokeev M. S., Kargin, Yu F., Irtyugo L. A., Belousova, N., V, Denisov V. M.
Заглавие : Synthesis, crystal structure, and thermodynamic properties of CuSm2Ge2O8
Коллективы : Siberian Federal University [FSRZ2020-0013]
Место публикации : Russ. J. Inorg. Chem. - 2021. - Vol. 66, Is. 12. - P.1817-1821. - ISSN 0036-0236, DOI 10.1134/S0036023621120020. - ISSN 1531-8613(eISSN)
Примечания : Cited References: 30. - This work was carried out with partial financial support within the framework of the State assignment for science of the Siberian Federal University, project number FSRZ2020-0013
Предметные рубрики: TEMPERATURE HEAT-CAPACITY
CU-O
PREDICTION
GERMANATES
GROWTH
Аннотация: Copper samarium germanate CuSm2Ge2O8 have been synthesized by the ceramic method from CuO, Sm2O3, and GeO2 in air at the final calcination temperature 1273 K (200 h), and its crystal structure has been determined (space group Cm; a = 9.7592(2) Å, b = 15.2608(4) Å, c = 8.2502(2) Å, β = 148.2566(8)°, V = 646.46(3) Å3). The temperature dependence of the molar heat capacity Cp = f(T) measured in the temperature range 350–1000 K shows a maximum at Tmax = 498.5 K caused by the phase transition. Thermodynamic properties have been calculated from experimental data.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Pichugin K. N., Sadreev A. F.
Заглавие : Giant resonant enhancement of optical binding of dielectric disks
Место публикации : J. Opt. Soc. Am. B. - 2020. - Vol. 37, Is. 11. - P.3335-3340. - ISSN 07403224 (ISSN), DOI 10.1364/JOSAB.402659
Примечания : Cited References: 30. - Russian Science Support Foundation (19-02-00055)
Аннотация: Two-fold variation over the aspect ratio of each disk and distance between disks gives rise to numerous events of avoided crossing of resonances of individual disks. For these events, the hybridized anti-bonding resonant modes can acquire a morphology close to the Mie resonant mode with the high orbital momentum of an equivalent sphere. The �� factor of such resonance can exceed the �� factor of an isolated disk by two orders of magnitude. We show that dual incoherent counterpropagating coaxial Bessel beams with power 1mW/µm2 with frequency resonant to such anti-bonding Mie-like modes result in unprecedented optical binding forces up to tens of nano-Newtons for silicon micrometer-sized disks. We show also that the magnitude and sign of optical forces depend strongly on the longitudinal wave vector of the Bessel beams.
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10.

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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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., 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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13.

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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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lundin A. A., Zobov V. E.
Заглавие : Asymptotic similarity of time correlation functions and shape of the 13C and 29Si NMR spectra in diamond and silicon
Коллективы : Institute of Chemical Physics of the Russian Academy of Science [0082-2018-0005, TSITIS AAAA-A18-118020690203]
Место публикации : J. Exp. Theor. Phys. - 2018. - Vol. 127, Is. 2. - P.305-315. - ISSN 1063-7761, DOI 10.1134/S1063776118080216. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 47. - We thank V.A. Atsarkin, V.V. Demidov, F.S. Dzheparov, and E. B. Feldman for the discussion of our results. This work was supported by a subsidy allocated by the Institute of Chemical Physics of the Russian Academy of Science for the State assignment, theme 0082-2018-0005, code TSITIS AAAA-A18-118020690203.
Предметные рубрики: SPIN SYSTEMS
LINE-SHAPES
RELAXATION
SOLIDS
PARAMAGNETS
RESONANCE
Аннотация: Based on the proposed theory, we have investigated the shape of the NMR absorption spectra for 13C and 29Si nuclei in diamond and silicon crystals attributable to the internuclear dipole–dipole interaction. In accordance with the available experimental data, we have considered both crystals with a 100% content of magnetoactive isotopes and crystals with a comparatively low dilution by nonmagnetic nuclei. The time correlation functions (the first of which is the Fourier transform of the NMR spectrum) arising in an infinite chain of coupled differential equations are shown to be mutually similar with a slight time delay. The proposed theory allows the spectrum to be calculated analytically. The results obtained agree satisfactorily with the experimental ones. It is noted that the mutual similarity of the time correlation functions is probably a corollary of the development of dynamical chaos in the system.
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15.

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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16.

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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17.

Вид документа : Статья из сборника (выпуск продолж. издания)
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Green's functions of polaritons in a medium with zero-mean inhomogeneous coupling parameter
Коллективы : International Conference on Photonics of Nano- and Bio-Structures, International Conference on Photonics of Nano- and Bio-Structures
Место публикации : Physics Procedia: Elsevier, 2017. - Vol. 86. - P.117-121. - , DOI 10.1016/j.phpro.2017.01.031
Примечания : Cited References: 10
Ключевые слова (''Своб.индексиров.''): electromagnetic waves--optical phonons--crossing resonance--polaritons--green's functions--self-consistent approximation
Аннотация: Dynamic susceptibilities (Green's functions) of the interacting electromagnetic waves G”e(ω) and optical phonons G”u(ω) in a medium with zero-mean inhomogeneous coupling parameter have been considered. The calculation was performed using a self-consistent approximation for the two stochastically interacting wave fields. It is shown that on the tops of the resonance maxima of the imaginary parts of the Green functions the fine structure is formed: a minimum (dip) on the top of G”e(ω) and narrow maximum (peak) on the top of G”u(ω). With increasing the correlation wavenumber of inhomogeneities kc (i.e., with decreasing the size of inhomogeneities), the width of the peak on G”u(ω) decreases, and two resonance maxima in the function G”e(ω) are formed. Because of the large difference in the speeds of light and optical phonons, the fine structure of the polaritons is manifested itself more clearly and saved to a much larger values of kc, than for the studied earlier crossing resonance of spin and elastic waves.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S., Tsikalov D. S.
Заглавие : Self-consistent approximation: Development and application to the problem of waves in inhomogeneous media
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН , SB of the Russian Academy of Sciences [II.2P (0356-2015-0410)]
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2017. - Vol. 440: EURO-Asian Symposium on Trends in Magnetism (EASTMAG) (AUG 15-19, 2016, Siberian Fed Univ, Krasnoyarsk, RUSSIA). - P.83-86. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2016.12.058. - ISSN 1873-4766(eISSN)
Примечания : Cited References:20. - This work was supported in part by the Complex Program No II.2P (0356-2015-0410) of the SB of the Russian Academy of Sciences.
Предметные рубрики: SUPERCONDUCTING CRITICAL-TEMPERATURE
MIGDALS THEOREM
VERTEX FUNCTION
Ключевые слова (''Своб.индексиров.''): self-consistent approximation--greens functions--vertex corrections--inhomogeneities--correlations--dynamic susceptibility
Аннотация: A new self-consistent approximation proposed earlier, is compared with various existing approximations, as well as with a numerical simulation of solutions of the wave equation for a medium with one-dimensional inhomogeneities. The Green's function, found using the new approach, is the closest to the result obtained by the numerical simulation. The results of the work show that the new approach has undoubted advantages in the study of stochastic problems in media with longwave inhomogeneities. The new self-consistent approximation in some cases has advantages over a numerical method: a more rapid process of calculation and the possibility of consideration of three-dimensional problems.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivantsov I. D., Ferraz A., Kochetov E.
Заглавие : Quantum Monte Carlo study of the itinerant-localized model of strongly correlated electrons: Spin-spin correlation functions
Место публикации : Phys. Rev. B: American Physical Society, 2016. - Vol. 94, Is. 23. - Ст.235118. - ISSN 10980121 (ISSN), DOI 10.1103/PhysRevB.94.235118
Примечания : Cited References: 15
Аннотация: We perform quantum Monte Carlo simulations of the itinerant-localized periodic Kondo-Heisenberg model for the underdoped cuprates to calculate the associated spin correlation functions. The strong electron correlations are shown to play a key role in the abrupt destruction of the quasi-long-range antiferromagnetic order in the lightly doped regime. © 2016 American Physical Society.
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20.

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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