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1.


    VALKOV, V. V.
    UNITARY TRANSFORMATIONS OF THE GROUP U(N) AND DIAGONALIZATION OF MULTILEVEL HAMILTONIANS / V. V. VALKOV // Theor. Math. Phys. - 1988. - Vol. 76, Is. 1. - P. 766-772, DOI 10.1007/BF01029435. - Cited References: 20 . - ISSN 0040-5779
РУБ Physics, Multidisciplinary + Physics, Mathematical


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Val'kov, V. V.
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2.


    Valkov, V. V.
    Application of indefinite metric for transition to bose description of Su(3) hamiltonians - excitation spectrum of spin nematics / V. V. Valkov, T. A. Valkova // Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 99, Is. 6. - P. 1881-1897. - Cited References: 37 . - ISSN 0044-4510
РУБ Physics, Multidisciplinary
Рубрики:
BIQUADRATIC EXCHANGE
   PHASE-TRANSITIONS

   DIAGRAM TECHNIQUE

   MAGNETISM

   FIELD

   STATE

Аннотация: A procedure is developed for a correct transition to the Bose representation for quantum SU(3) Hamiltonians. The analysis is carried out for a spin nematic by applying the indefinite metric formalism and pseudo-Hubbard operators. An important aspect of the theory is that the finiteness of the number of physical states is taken into account. This is attained by introducing and consistently taking into account the metric operator for which purpose a simple expression in terms of Bose operators is suggested. It is shown that in this approach the quantum Bose analog of the Hamiltonian is an Hermitian operator. This circumstance removes a number of principle contradictions which appeared previously on application of the Bose analog of the Hamiltonian derived by virtually identifying the Hubbard and pseudo-Hubbard operators and ignoring the finiteness of the number of physical states. The integral equations defining the chief characteristics of the system are obtained and solved analytically for the spin-nematic state of a magnet with S = 1 and by taking into account anharmonic effects. This permits one to write down in nonlinear theory explicit expressions for the two branches of the quantum excitation spectrum. The character of the renormalization of the spectrum parameters due to the presence of zero-point quantum oscillations is studied. The renormalization of the critical field on transition of the system from the spin nematic state is calculated analytically.

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Доп.точки доступа:
Valkova, T. A.; Вальков, Валерий Владимирович
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3.


    Rotter, I.
    Influence of branch points in the complex plane on the transmission through double quantum dots / I. . Rotter, A. F. Sadreev // Phys. Rev. E. - 2004. - Vol. 69, Is. 6. - Ст. 66201, DOI 10.1103/PhysRevE.69.066201. - Cited References: 25 . - ISSN 1539-3755
РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
ELECTRON-ATOM SCATTERING
   S-MATRIX

   DOUBLE POLES

   CONTINUUM

   SYSTEM

   MODEL

Кл.слова (ненормированные):
Eigenvalues and eigenfunctions -- Hamiltonians -- Mathematical models -- Matrix algebra -- Probability -- Resonance -- Scattering -- Wave propagation -- Branch points -- Open quantum systems -- Propagating modes -- Quantum computing devices -- Semiconductor quantum dots
Аннотация: We consider single-channel transmission through a double quantum dot system consisting of two single dots that are connected by a wire and coupled each to one lead. The system is described in the framework of the S matrix theory by using the effective Hamiltonian of the open quantum system. It consists of the Hamiltonian of the closed system (without attached leads) and a term that accounts for the coupling of the states via the continuum of propagating modes in the leads. This model allows one to study the physical meaning of branch points in the complex plane. They are points of coalesced eigenvalues and separate the two scenarios with avoided level crossings and without any crossings in the complex plane. They influence strongly the features of transmission through double quantum dots.

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Держатели документа:
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Linkoping Univ, Dept Phys & Measurement, S-58183 Linkoping, Sweden
Astafev Kransnoyarsk Pedag Univ, Krasnoyarsk 660049, Russia
ИФ СО РАН
Max-Planck-Inst. Phys. Komplexer S., D-01187 Dresden, Germany
Kirensky Institute of Physics, Krasnoyarsk, 660036, Russian Federation
Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden
Astaf'ev Krasnoyarsk Pedagogical U., 89 Lebedeva, Krasnoyarsk, 660049, Russian Federation

Доп.точки доступа:
Sadreev, A. F.; Садреев, Алмаз Фаттахович
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4.


    Bulgakov, E. N.
    Statistics of wave functions and currents induced by spin-orbit interaction in chaotic billiards / E. N. Bulgakov, A. F. Sadreev // Phys. Rev. E. - 2004. - Vol. 70, Is. 5. - Ст. 56211, DOI 10.1103/PhysRevE.70.056211. - Cited References: 33 . - ISSN 1539-3755
РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
HELMHOLTZ-EQUATION
   PERSISTENT CURRENTS

   ELECTRON-GAS

   RINGS

   EIGENFUNCTIONS

   SYSTEMS

   PHASE

Кл.слова (ненормированные):
Approximation theory -- Chaos theory -- Degrees of freedom (mechanics) -- Eigenvalues and eigenfunctions -- Electric field effects -- Electric potential -- Electron gas -- Hamiltonians -- Heterojunctions -- Microwaves -- Statistical methods -- Chaotic Robnik billiards -- Current distributions -- Spin-orbit interaction (SOI) -- Wave functions -- Quantum theory
Аннотация: We show that the wave function and current statistics in chaotic Robnik billiards crucially depend on the constant of the spin-orbit interaction (SOI). For small constant the current statistics is described by universal current distributions derived for slightly opened chaotic billiards [Saichev et al. J. Phys. A. 35, L87 (2002)] although one of the components of the spinor eigenfunctions is not universal. For strong SOI both components of the spinor eigenstate are complex random Gaussian fields. This observation allows us to derive the distributions of spin-orbit persistent cut-rents which well describe numerical statistics. For intermediate values of the statistics of the eigenstates and currents, both are deeply nonuniversal.

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Держатели документа:
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Astafev Krasnoyarsk Pedag Univ, Lebedeva 660049 89, Russia
Linkoping Univ, IFM, S-58183 Linkoping, Sweden
ИФ СО РАН
Kirensky Institute of Physics, 660036, Krasnoyarsk, Russian Federation
Astaf'ev Krasnoyarsk Pedagogical U., 660049, Lebedeva, 89, Russian Federation
IFM, Linkoping University, S-581 83 Linkoping, Sweden

Доп.точки доступа:
Sadreev, A. F.; Садреев, Алмаз Фаттахович; Булгаков, Евгений Николаевич
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5.


   
    Effective parameters of the band dispersion in n-type high-T-c superconductors / M. M. Korshunov [et al.] // Physica C. - 2004. - Vol. 402, Is. 4. - P. 365-370, DOI 10.1016/j.physc.2003.10.017. - Cited References: 32 . - ISSN 0921-4534
РУБ Physics, Applied
Рубрики:
DOPED CUPRATE SUPERCONDUCTORS
   TIGHT-BINDING METHOD

   QUASI-PARTICLES

   COPPER OXIDES

   LA2-XSRXCUO4

   SYMMETRY

   MODEL

   EVOLUTION

   ORDER

Кл.слова (ненормированные):
high-T-c superconductivity -- electronic correlations -- electron-doped cuprates -- Electron-doped cuprates -- Electronic correlations -- High-Tc superconductivity -- Approximation theory -- Atomic physics -- Band structure -- Binding energy -- Charge transfer -- Correlation methods -- Doping (additives) -- Electronic structure -- Hamiltonians -- Mathematical models -- Mathematical operators -- Oxide superconductors -- Perturbation techniques -- Photoelectron spectroscopy -- Atomic orbitals -- Conduction band -- Electron doped cuprates -- Electron spins -- Valence band -- High temperature superconductors
Аннотация: The electronic structure of electron-doped cuprates is discussed in the regions of small and optimal doping. For optimal doping we obtain the parameters from a simple tight-binding analysis by fitting ARPES data, and for small doping we study the band structure by the generalized tight-binding method that takes strong electronic correlations into account explicitly. This method has also reproduced well the ARPES data for small doping. The effective low-energy Hamiltonian is the t-t'-J model with hopping parameters t and t'. We compare both methods and find very good agreement for the value of t while t' is different because it is caused by the different contribution of the short-range spin correlations. (C) 2003 Elsevier B.V. All rights reserved.

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Держатели документа:
Free Univ Berlin, Inst Theoret Phys, D-14195 Berlin, Germany
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН
L.V. Kirensky Institute of Physics, Siberian Branch, Russian Academy of Science, Krasnoyarsk 660036, Russian Federation
Inst. fur Theoretische Physik, Freie Universitat Berlin, Arnimallee 14, D-14195 Berlin, Germany

Доп.точки доступа:
Korshunov, M. M.; Коршунов, Максим Михайлович; Gavrichkov, V. A.; Гавричков, Владимир Александрович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Manske, D.; Eremin, I.
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6.


   
    Prediction of the in-gap states above the top of the valence band in undoped insulating cuprates due to the spin-polaron effect / S. G. Ovchinnikov [et al.] // J. Phys.: Condens. Matter. - 2004. - Vol. 16, Is. 8. - P. L93-L100, DOI 10.1088/0953-8984/16/8/L04. - Cited References: 25 . - ISSN 0953-8984
РУБ Physics, Condensed Matter
Рубрики:
ELECTRONIC-STRUCTURE
   LA2-XSRXCUO4

   MODEL

   ANTIFERROMAGNETISM

   SPECTRA

   OXIDES

Кл.слова (ненормированные):
Quasiparticle band structure -- Spin-polaron effect -- Antiferromagnetic materials -- Approximation theory -- Doping (additives) -- Electronic structure -- Hamiltonians -- Insulation -- Magnetic fields -- Strontium compounds -- Thermal effects -- Lanthanum compounds
Аннотация: In the framework of the generalized tight binding method we have calculated the quasiparticle band structure and the spectral functions of the undoped cuprates such as La2CuO4, Sr2CUO2Cl2 etc. Due to spin fluctuations the in-gap state appears above the top of the valence band in the undoped antiferromagnetic insulator similar to in-gap states induced by hole doping. In the ARPES experiments the in-gap states can be detected as weak low energy satellites.

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Держатели документа:
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
L V Kirensky Institute of Physics, Siberian Branch, Russian Academy of Science, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Borisov, A. A.; Gavrichkov, V. A.; Гавричков, Владимир Александрович; Korshunov, M. M.; Коршунов, Максим Михайлович
}
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7.


   
    Influence of magnetic ordering on the resistivity anisotropy of alpha-MnS single crystal / S. S. Aplesnin [et al.] // Solid State Commun. - 2004. - Vol. 129, Is. 3. - P. 195-197 ; Solid State Commun. - 2004. - Vol. 129, Is. 3. - P. 195-197, DOI 10.1016/j.ssc.2003.09.028. - Cited References: 7 . - ISSN 0038-1098. - Вариант Sopus
РУБ Physics, Condensed Matter

Кл.слова (ненормированные):
anisotropy of resistivity -- optical gap -- D. Anisotropy of resistivity -- D. Optical gap -- Antiferromagnetism -- Band structure -- Bandwidth -- Diffractometers -- Electron transitions -- Fermi level -- Hamiltonians -- Light absorption -- Magnetic anisotropy -- Magnetization -- Single crystals -- Spectroscopic analysis -- X ray diffraction analysis -- Coulomb repulsion -- Resistivity anisotropy -- Semiconducting manganese compounds -- D. Anisotropy of resistivity -- D. Optical gap -- Antiferromagnetism -- Band structure -- Bandwidth -- Diffractometers -- Electron transitions -- Fermi level -- Hamiltonians -- Light absorption -- Magnetic anisotropy -- Magnetization -- Single crystals -- Spectroscopic analysis -- X ray diffraction analysis -- Coulomb repulsion -- Resistivity anisotropy -- Semiconducting manganese compounds
Аннотация: The resistivity and the optical absorbtion spectra of single crystal alpha-MnS are studied in the temperature range 80-300 K along two directions [100] and [111]. Strong anisotropy of the resistivity, and the shift of absorbtion spectra band edge below T < 160 K are explained in terms of model involving delocalized holes in 3d-band manganese ions interacting with localized spins by using the sd-model. (C) 2003 Elsevier Ltd. All rights reserved.

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН
Siberian Branch, Academcumpus, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Siberian Branch, Academcumpus, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Aplesnin, S. S.; Аплеснин, Сергей Степанович; Petrakovskii, G. A.; Петраковский, Герман Антонович; Ryabinkina, L. I.; Рябинкина, Людмила Ивановна; Abramova, G. M.; Абрамова, Галина Михайловна; Kiselev, N. I.; Romanova, O. B.; Романова, Оксана Борисовна

}
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8.


    Rotter, I.
    Zeros in single-channel transmission through double quantum dots / I. . Rotter, A. F. Sadreev // Phys. Rev. E. - 2005. - Vol. 71, Is. 4. - Ст. 46204, DOI 10.1103/PhysRevE.71.046204. - Cited References: 28 . - ISSN 1063-651X
РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
PHASE EVOLUTION
   RESONANCE

   TRANSPORT

   SYSTEMS

Кл.слова (ненормированные):
Fano interference -- Fano resonances -- Overlapping resonances -- Transmission amplitude -- Channel capacity -- Eigenvalues and eigenfunctions -- Function evaluation -- Hamiltonians -- Mathematical models -- Mathematical operators -- Matrix algebra -- Resonance -- Signal interference -- Semiconductor quantum dots
Аннотация: By using a simple model we consider single-channel transmission through a double quantum dot that consists of two single dots coupled by a wire of finite length L. Each of the two single dots is characterized by a few energy levels only, and the wire is assumed to have only one level whose energy depends on the length L. The transmission is described by using S matrix theory and the effective non-Hermitian Hamilton operator H-eff of the system. The decay widths of the eigenstates of H-eff depend strongly on energy. The model explains the origin of the transmission zeros of the double dot that is considered by us. Mostly, they are caused by (destructive) interferences between neighboring levels and are of first order. When, however, both single dots are identical and their transmission zeros are of first order, those of the double dot are of second order. First-order transmission zeros cause phase jumps of the transmission amplitude by pi, while there are no phase jumps related to second-order transmission zeros. In this latter case, a phase jump occurs due to the fact that the width of one of the states vanishes when crossing the energy of the transmission zero. The parameter dependence of the widths of the resonance states is determined by the spectral properties of the two single dots.

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Держатели документа:
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden
Astafev Krasnoyarsk Pedag Univ, Krasnoyarsk 660049, Russia
ИФ СО РАН
Max-Planck-Inst. Phys. Komplexer S., D-01187 Dresden, Germany
Kirensky Institute of Physics, Krasnoyarsk, 660036, Russian Federation
Dept. of Phys. and Msrmt. Technology, Linkoping University, S-58183 Linkoping, Sweden
Astaf'ev Krasnoyarsk Pedagogical U., Krasnoyarsk, 660049, Russian Federation

Доп.точки доступа:
Sadreev, A. F.; Садреев, Алмаз Фаттахович
}
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9.


    Korshunov, M. M.
    Effective Hamiltonian and the properties of normal and superconductive phases of n-type cuprates / M. M. Korshunov, S. G. Ovchinnikov, A. V. Sherman // Physica B. - 2005. - Vol. 359: International Conference on Strongly Correlated Electron Systems (SCES 04) (JUL 26-30, 2004, Karlsruhe, GERMANY). - P. 521-523, DOI 10.1016/j.physb.2005.01.134. - Cited References: 13 . - ISSN 0921-4526
РУБ Physics, Condensed Matter
Рубрики:
MODEL
   SYMMETRY

Кл.слова (ненормированные):
strong electron correlations -- superconductivity -- multiband p-d model -- n-type cuprates -- Multiband p-d model -- n-type cuprates -- Strong electron correlations -- Superconductivity -- Antiferromagnetism -- Correlation theory -- Fermi surface -- Hamiltonians -- Mathematical models -- Microscopic examination -- Oxide superconductors -- Phase diagrams -- Semiconductor doping -- Generalized tight-binding (GTB) -- Multiband p-d models -- N-type cuprates -- Single electron correlations -- Superconductivity
Аннотация: In the framework of the effective low-energy model for high-T-c, cuprates with account for three-center interaction terms and spin fluctuations the properties of normal and superconducting phases of n-type cuprates are investigated. Microscopic model parameters were obtained from ARPES data in undoped compounds. Obtained evolution of the chemical potential with doping, Fermi surface at optimal doping, and T-c(x) phase diagram are in remarkably good agreement with the experiment. (c) 2005 Elsevier B.V. All rights reserved.

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Держатели документа:
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Univ Tartu, Inst Phys, EE-51014 Tartu, Estonia
ИФ СО РАН
LV Kirensky Institute of Physics, Siberian Br. of Russ. Acad. of Sci., Krasnoyarsk, 660036, Russian Federation
Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Sherman, A. V.; Коршунов, Максим Михайлович
}
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10.


    Rotter, I.
    Avoided level crossings, diabolic points, and branch points in the complex plane in an open double quantum dot / I. . Rotter, A. F. Sadreev // Phys. Rev. E. - 2005. - Vol. 71, Is. 3. - Ст. 36227, DOI 10.1103/PhysRevE.71.036227. - Cited References: 49 . - ISSN 1063-651X
РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
BERRY TOPOLOGICAL PHASE
   EXCEPTIONAL POINTS

   GEOMETRIC PHASES

   NUCLEAR REACTIONS

   RESONANCE STATES

   UNIFIED THEORY

   S-MATRIX

   CONTINUUM

   REPULSION

   INTERFEROMETER

Кл.слова (ненормированные):
Branch points in the complex plane (BPCP) -- Diabolic points (DP) -- Geometric phases -- Riemann sheets -- Eigenvalues and eigenfunctions -- Electron energy levels -- Functions -- Hamiltonians -- Quantum theory -- Resonance -- Topology -- Semiconductor quantum dots
Аннотация: We study the spectrum of an open double quantum dot as a function of different system parameters in order to receive information on the geometric phases of branch points in the complex plane (BPCP). We relate them to the geometrical phases of the diabolic points (DPs) of the corresponding closed system. The double dot consists of two single dots and a wire connecting them. The two dots and the wire are represented by only a single state each. The spectroscopic values follow from the eigenvalues and eigenfunctions of the Hamiltonian describing the double dot system. They are real when the system is closed, and complex when the system is opened by attaching leads to it. The discrete states as well as the narrow resonance states avoid crossing. The DPs are points within the avoided level crossing scenario of discrete states. At the BPCP, width bifurcation occurs. Here, different Riemann sheets evolve and the levels do not cross anymore. The BPCP are physically meaningful. The DPs are unfolded into two BPCP with different chirality when the system is opened. The geometric phase that arises by encircling the DP in the real plane, is different from the phase that appears by encircling the BPCP. This is found to be true even for a weakly opened system and the two BPCP into which the DP is unfolded.

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Держатели документа:
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden
Astafev Krasnoyarsk Pedag Univ, Krasnoyarsk 660049, Russia
ИФ СО РАН
Max-Planck-Inst. Physik Komplexer S., D-01187 Dresden, Germany
Kirensky Institute of Physics, 660036, Krasnoyarsk, Russian Federation
Dept. of Physics and Measurement, Technology Linkoping University, S-581 83 Linkoping, Sweden
Astafev Krasnoyarsk Pedagogical U., 660049 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Sadreev, A. F.; Садреев, Алмаз Фаттахович
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