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1.


   
    On the non-orthogonality problem in the description of quantum devices / J. . Fransson [et al.] // Physica B. - 1999. - Vol. 272, Is. 1-4. - P. 28-30, DOI 10.1016/S0921-4526(99)00343-9. - Cited References: 8 . - ISSN 0921-4526
РУБ Physics, Condensed Matter
Рубрики:

Кл.слова (ненормированные):
non-orthogonality -- current -- tunneling -- Correlation methods -- Electric contacts -- Electric currents -- Electron energy levels -- Electron tunneling -- Equations of motion -- Green's function -- Mathematical operators -- Matrix algebra -- Hubbard operators -- Potential barriers -- Tunneling currents -- Semiconductor quantum dots
Аннотация: An approach which allows to include the corrections from non-orthogonality of electron states in contacts and quantum dots is developed. Comparison of the energy levels and charge distributions of electrons in 1D quantum dot (QD) in equilibrium, obtained within orthogonal (OR) and non-orthogonal representations (NOR), with the exact ones shows that the NOR provides a considerable improvement, for levels below the top of barrier. The approach is extended to non-equilibrium states. A derivation of the tunneling current through a single potential barrier is performed using equations of motion for correlation functions. A formula for transient current derived by means of the diagram technique for Hubbard operators is given for the problem of QD with strongly correlated electrons interacting with electrons in contacts. The non-orthogonality renormalizes the tunneling matrix elements and spectral weights of Green functions. (C) 1999 Elsevier Science B.V. All rights reserved.

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Держатели документа:
Univ Uppsala, Condensed Matter Theory Grp, S-75121 Uppsala, Sweden
RAS, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
Condensed Matter Theory Group, Uppsala University, Box 530, 751 21, Uppsala, Sweden
Kirensky Institute of Physics, RAS, 660036, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Fransson, J.; Eriksson, O.; Johansson, B.; Sandalov, I. S.; Сандалов, Игорь Семёнович; International Conference on Nonequilibrium Carrier Dynamics in Semiconductors(11 ; 1999 ; July ; 19-23 ; Kyoto, Japan)
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2.


    Kuz'min, E. V.
    Quantum spin liquid in the FCC lattice / E. V. Kuz'min // J. Exp. Theor. Phys. - 2003. - Vol. 96, Is. 1. - P. 129-139, DOI 10.1134/1.1545392. - Cited References: 12 . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
HEISENBERG-ANTIFERROMAGNET
   TRANSITION

Кл.слова (ненормированные):
Antiferromagnetism -- Green's function -- Linear systems -- Magnetic couplings -- Quantum theory -- Thermodynamic properties -- Antiferromagnetic interactions -- Green temperature functions -- Heisenberg model -- Quantum spin liquid -- Spin system -- Spin-wave theory -- Crystal lattices
Аннотация: The properties of the spin system in the FCC lattice described by the Heisenberg model (s=1/2) with antiferromagnetic interactions between the nearest neighbors were studied. It was shown within the framework of spin-wave theory that long-range antiferromagnetic order was absent because of frustration of exchange coupling and transverse quantum spin fluctuations. The system was in the quantum spin liquid state. A method for describing it within linear second-order theory with self-consistently calculated parameters was suggested. It was proved that the ground spin liquid state was singlet. The thermodynamic properties of the spin liquid in the whole temperature range and the character of spatial spin correlations, which had alternating signs and a finite correlation length, were determined. The theory was constructed based on the method of two-time Green temperature functions. (C) 2003 MAIK "Nauka/Interperiodica".

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Div, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russian Federation
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3.


    Ovchinnikov, S. G.
    The energy band structure and optical spectra of FeBO3 calculated with allowance for strong electron correlations / S. G. Ovchinnikov, V. N. Zabluda // J. Exp. Theor. Phys. - 2004. - Vol. 98, Is. 1. - P. 135-143, DOI 10.1134/1.1648107. - Cited References: 32. - This study was supported by the Russian Foundation for Basic Research (project no. 03-02-16286) and by the “Strongly Correlated Electrons” Program of the Department of Physical Sciences of the Russian Academy of Sciences . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
PHASE-TRANSITION
   HIGH-PRESSURE

   FERROMAGNETISM

   MODEL

Кл.слова (ненормированные):
Atomic physics -- Band structure -- Charge transfer -- Excitons -- Green's function -- Light absorption -- Dielectric gap -- Energy band structure -- Lehmann spectral representation -- Optical spectra -- Iron compounds
Аннотация: A model of the energy band structure of iron borate (FeBO3) is proposed that combines a one-electron description of the sp states of boron and oxygen with a many-electron description of the d states of iron. The Green functions of d electrons are calculated using the exact Lehmann spectral representation. The energies of the d-type quasiparticles are calculated using terms of the d(4) , d(5) , and d(6) electron configurations. The optical absorption spectrum of FeBO3 is determined by local excitons and by the electron excitations with charge transfer. The latter excitations control the nature of the dielectric gap in FeBO3 crystals. The model parameters are determined from a comparison to the exciton energies. The density of single-particle states in FeBO3 is calculated. The main bands in the calculated optical absorption spectrum agree well with experimental data for energies up to 3 eV. (C) 2004 MAIK "Nauka/Interperiodica".

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Публикация на русском языке Овчинников, Сергей Геннадьевич. Энергетическая структура и оптические спектры FeBO[3] с учетом сильных электронных корреляций [Текст] / С. Г. Овчинников, В. Н. Заблуда // Журн. эксперим. и теор. физ. - 2004. - Т. 125 Вып. 1. - С. 150-159

Держатели документа:
Russian Acad Sci, Siberian Div, Kirensky Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Zabluda, V. N.; Заблуда, Владимир Николаевич; Овчинников, Сергей Геннадьевич
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4.


    Ignatchenko, V. A.
    High-Frequency Susceptibility of a Superlattice with 2D Inhomogeneities / V. A. Ignatchenko, Y. I. Mankov, D. S. Tsikalov // J. Exp. Theor. Phys. - 2008. - Vol. 107, Is. 4. - P. 603-611, DOI 10.1134/S1063776108100075. - Cited References: 26. - This work was supported in part by grant no. 3818.2008.3 from the President of Russia in accordance with the program supporting leading scientific schools. . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
SPIN-WAVE SUSCEPTIBILITY
   PERIODIC MULTILAYERS

   LOCALIZATION

   SYSTEMS

   SPECTRUM

   DISORDER

   MEDIA

Кл.слова (ненормированные):
Energy conservation -- Energy gap -- Energy management -- Frequency bands -- Gallium alloys -- Green's function -- Probability density function -- Three dimensional -- Band gaps -- Energy conservation laws -- Green functions -- High frequencies -- Imaginary parts -- Magnon crystals -- Scattered waves -- Superlattice layers -- Wave spectrums -- Phase interfaces
Аннотация: We investigate the high-frequency susceptibility (Green function) of an initially sinusoidal 1D superlattice with 2D phase inhomogeneities that model the deformations of the interfaces between the superlattice layers. For waves propagating along the superlattice axis ( the geometry of a photon or magnon crystal), we have found a peculiar behavior of the imaginary part of the Green function that consists in a significant difference between the peaks corresponding to the edges of the band gap in the wave spectrum. The peak corresponding to the lower-frequency band edge remains essentially unchanged as the root-mean-square fluctuation of the 2D inhomogeneities. 2 increases, while the peak corresponding to the higher-frequency band edge broaden and decreases sharply in height until its complete disappearance with increasing gamma(2). This behavior of the peaks corresponds to a band gap closure mechanism that differs from the traditional one characteristic of 1D and 3D inhomogeneities. These effects can be explained by a peculiarity of the energy conservation laws for the incident and scattered waves for 2D inhomogeneities in a 1D superlattice.

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Держатели документа:
[Ignatchenko, V. A.
Mankov, Yu. I.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Mankov, Yu. I.
Tsikalov, D. S.] Siberian Fed Univ, Krasnoyarsk 660062, Russia
ИФ СО РАН
L.V. Kirenskii Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036, Russian Federation
Siberian Federal University, Krasnoyarsk 660062, Russian Federation

Доп.точки доступа:
Mankov, Y. I.; Tsikalov, D. S.; Цикалов, Денис Сергеевич; Игнатченко, Вальтер Алексеевич
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5.


    Val'kov, V. V.
    Spin-Fluctuation Renormalization of the Temperature of a Superconducting s-Phase in Rare-Earth Intermetallides / V. V. Val'kov, D. M. Dzebisashvili // J. Exp. Theor. Phys. - 2008. - Vol. 107, Is. 4. - P. 679-691, DOI 10.1134/S1063776108100166. - 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). . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
HEAVY-FERMION SUPERCONDUCTORS
   PERIODIC ANDERSON MODEL

   WAVE SUPERCONDUCTIVITY

   PERTURBATION-THEORY

   MECHANISM

   VALENCE

   SYSTEMS

   LATTICE

   STATE

Кл.слова (ненормированные):
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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Держатели документа:
[Val'kov, V. V.
Dzebisashvili, D. M.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Val'kov, V. V.
Dzebisashvili, D. M.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Val'kov, V. V.] Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
Siberian Federal University, Krasnoyarsk 660041, Russian Federation
Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Вальков, Валерий Владимирович
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6.


   
    Spin fluctuation processes in the problem of s-wave superconducting phase of the heavy-fermion intermetallides / V. V. Val'kov, D. M. Dzebisashvili // J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 1, DOI 10.1088/1742-6596/200/1/012030 . - ISSN 1742-6588
Кл.слова (ненормированные):
Anomalous component -- Critical points -- Critical temperatures -- Heavy-fermion -- Hubbard operators -- Kinematic mechanism -- One-loop approximation -- Periodic Anderson model -- Self-consistent equations -- Skutterudites -- Strong electron correlations -- Superconducting phase -- Superconducting phase transitions -- Green's function -- Mathematical operators -- Phase diagrams -- Shear waves -- Spin fluctuations -- Superconductivity -- Phase transitions
Аннотация: In the framework of the periodic Anderson model in the limit of strong electron correlations a theory of s-wave superconductivity (this phase has been recently discovered in the skutterudite LaFe4P12) has been developed. The theory is based on kinematic mechanism, provided that the spin fluctuation processes (SFP) are taken into account.To obtain the self-consistent equations for the superconducting phase the diagram technique for Hubbard operators has been used. The exact representations of normal and anomalous Green's functions in terms of normal and anomalous components of mass and strength operators have been obtained. A set of integral equations for superconducting phase was deduced with the assumption that SFP have been accounted for. In the solution of these equations normal and anomalous components of the mass and strength operators have been calculated in the one-loop approximation. Computation has revealed that SFP result in substantial decreasing of critical temperature Tc and shifting the concentration critical point of the superconducting phase transition. © 2010 IOP Publishing Ltd.

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Держатели документа:
L.V.Kirensky Institute of Physics, SB RAS, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович
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7.


    Val'kov, V. V.
    Thermodynamic properties of two-layer quasi-two-dimensional antiferromagnets / V. V. Val'kov, A. D. Fedoseev // Theor. Math. Phys. - 2011. - Vol. 168, Is. 3. - P. 1216-1224, DOI 10.1007/s11232-011-0099-6. - Cited References: 16. - This work was supported in part by the Russian Foundation for Basic Research (Grant No. 10-02-00251), the Presidium of the Russian Academy of Sciences (Fundamental Research Program "Quantum Physics of Condensed Matter"), the Siberian Branch of the Russian Academy of Sciences (Integration Project No. 53 and Lavrentiev Competition of Youth Projects, A. D. F.), the Ministry of Education and Science of the Russian Federation (Program "Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013), and the President of the Russian Federation (Grant No. MK-1300.2011.2, A. D. F.). . - ISSN 0040-5779
РУБ Physics, Multidisciplinary + Physics, Mathematical
Рубрики:
HEISENBERG-MODEL
   SPIN-WAVE

Кл.слова (ненормированные):
antiferromagnetism -- high-temperature superconductor -- Tyablikov approximation -- Green's function -- antiferromagnetism -- Green's function -- high-temperature superconductor -- Tyablikov approximation
Аннотация: For two-layer quasi-two-dimensional antiferromagnets of type YBaCuO in the Tyablikov approximation, we investigate the dependences of the energy spectrum and the temperature of transition into an ordered state on both the quasi-two-dimensionality parameter and the intensity of the exchange coupling of spin moments located in two close planes. We assume that the exchange parameters inside the CuO (2) planes are much greater than the exchange parameters resulting in coupling between a spin located on a plane of an elementary cell and a spin on another plane of a different elementary cell. The obtained expressions for the N,el temperature and for the sublattice magnetic moment at zero temperature describe the dependences of these quantities on the parameters of interplane exchange interactions.

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Держатели документа:
[Val'kov, V. V.
Fedoseev, A. D.] RAS, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk, Russia
Reshetnev Siberian State Aerosp Univ, Krasnoyarsk, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, RAS, Krasnoyarsk, Russian Federation
Reshetnev Siberian State Aerospace University, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Fedoseev, A. D.; Федосеев, Александр Дмитриевич; Вальков, Валерий Владимирович
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8.


    Ignatchenko, V. A.
    Spectral properties of superlattices with anisotropic inhomogeneities. The transition from 3D to 1D disorder / V. A. Ignatchenko, A. V. Pozdnyakov // Diffusion and Defect Data Pt.B: Solid State Phenomena. - 2011. - Vol. 168-169. - P. 85-88, DOI 10.4028/www.scientific.net/SSP.168-169.85 . - ISSN 1012-0394. - ISSN 9783-0378
Кл.слова (ненормированные):
Anisotropic inhomogeneities -- DOS -- Green's function -- Superlattice -- Susceptibility -- Waves -- Anisotropic inhomogeneities -- Continuous transitions -- Correlation properties -- Density of state -- Dynamic susceptibility -- Inhomogeneities -- Spectral properties -- Susceptibility -- Wave numbers -- Differential equations -- Magnetic susceptibility -- Superlattices -- Three dimensional -- Anisotropy
Аннотация: Waves in the superlattice (SL) contained inhomogeneities with anisotropic correlation properties are considered. The anisotropy of the correlations is characterized by the parameter ? = 1-k? / k ?, where k ? and k? are the correlation wave numbers along the axis of the SL and in the plane of its layers, respectively (r ? k ?-1 and r? = k?-1 are the correlation radii). Dependencies of both the dynamic susceptibility and density of states at the continuous transition from the isotropic three-dimensional inhomogeneities (? = 0 ) to the one-dimensional ones (? =1) have been obtained.

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Доп.точки доступа:
Pozdnyakov, A. V.; Игнатченко, Вальтер Алексеевич; Euro-Asian Symposium "Trends in MAGnetism"(4 ; 2010 ; Jun.-Jul. ; Ekaterinburg); "Trends in MAGnetism", Euro-Asian Symposium(4 ; 2010 ; Jun.-Jul. ; Ekaterinburg)
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9.


    Ignatchenko, V. A.
    Spectral Properties of Superlattices with Anisotropic inhomogeneities. The Transition from 3D to 1D Disorder / V. A. Ignatchenko, A. V. Pozdnyakov ; ed. ko, VA Ignatch // TRENDS IN MAGNETISM. Ser. Solid State Phenomena / Euro-Asian Symposium "Trends in MAGnetism": Nanospintronics (4 ; 2010 ; 28 June-2 July ; Ekaterinburg) : TRANS TECH PUBLICATIONS LTD, 2011. - Vol. 168-169. - P. 85-88, DOI 10.4028/www.scientific.net/SSP.168-169.85. - Cited References: 4 . - ISBN 1012-0394
РУБ Materials Science, Multidisciplinary + Physics, Condensed Matter

Кл.слова (ненормированные):
superlattice -- waves -- anisotropic inhomogeneities -- Green's function -- susceptibility -- DOS
Аннотация: Waves in the superlattice (SL) contained inhomogeneities with anisotropic correlation properties are considered. The anisotropy of the correlations is characterized by the parameter lambda=1-k(perpendicular to)/k(parallel to), where k(parallel to) and k(perpendicular to) are the correlation wave numbers along the axis of the SL and in the plane of its layers, respectively (r(parallel to) = k(parallel to)(-1) and r(perpendicular to) = k(perpendicular to)(-1) are the correlation radii). Dependencies of both the dynamic susceptibility and density of states at the continuous transition from the isotropic three-dimensional inhomogeneities (lambda=0) to the one-dimensional ones (lambda=1) have been obtained.

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Доп.точки доступа:
Pozdnyakov, A. V.; Ignatchenko, V. A. \ed.\; Игнатченко, Вальтер Алексеевич; Euro-Asian Symposium "Trends in MAGnetism"(4 ; 2010 ; Jun.-Jul. ; Ekaterinburg); "Trends in MAGnetism", Euro-Asian Symposium(4 ; 2010 ; Jun.-Jul. ; Ekaterinburg)
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10.


    Ignatchenko, V. A.
    Spectral properties of waves in superlattices with 2D and 3D inhomogeneities / V. A. Ignatchenko, D. S. Tsikalov // Journal of Experimental and Theoretical Physics. - 2011. - Vol. 113, Is. 2. - P. 232-244, DOI 10.1134/S1063776111080061 . - ISSN 1063-7761
Кл.слова (ненормированные):
Analytic expressions -- Brillouin zone boundary -- Density of state -- Dynamic susceptibility -- Inhomogeneities -- One-dimensional density -- Optical methods -- Optical structures -- Peak height -- Root mean squares -- Spectral properties -- Superlattice layers -- Two phase -- Wave numbers -- Green's function -- Magnetic susceptibility -- Optical multilayers -- Phase interfaces -- Three dimensional -- Superlattices
Аннотация: We investigate the dynamic susceptibility and one-dimensional density of states in an initially sinusoidal superlattice containing simultaneously 2D phase inhomogeneities simulating correlated rough-nesses of superlattice interfaces and 3D amplitude inhomogeneities of the superlattice layer materials. The analytic expression for the averaged Green's function of the sinusoidal superlattice with two phase inhomogeneities is derived in the Bourret approximation. It is shown that the effect of increasing asymmetry in the peak heights of dynamic susceptibility at the Brillouin zone boundary of the superlattice, which was discovered earlier [15] upon an increase in root-mean-square (rms) fluctuations, also takes place upon an increase in the correlation wavenumber of inhomogeneities. However, the peaks in this case also become closer, and the width and depth of the gap in the density of states decrease thereby. It is shown that the enhancement of rms fluctuations of 3D amplitude inhomogeneities in a superlattice containing 2D phase inhomogeneities suppresses the effect of dynamic susceptibility asymmetry and leads to a slight broadening of the gap in the density of states and a decrease in its depth. Targeted experiments aimed at detecting the effects studied here would facilitate the development of radio-spectroscopic and optical methods for identifying the presence of inhomogeneities of various dimensions in multilayer magnetic and optical structures. В© 2011 Pleiades Publishing, Ltd.

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Доп.точки доступа:
Tsikalov, D. S.; Цикалов, Денис Сергеевич; Игнатченко, Вальтер Алексеевич
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