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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : Electron-phonon interaction in cuprates with T and T '-structure in strongly correlated limit
Разночтения заглавия :авие SCOPUS: Electron-phonon interaction in cuprates with T and T′-structure in strongly correlated limit
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P451-452. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.195
Примечания : Cited References: 5
Ключевые слова (''Своб.индексиров.''): superconductivity--strong electron correlations--electron-phonon interaction--electron-phonon interaction--strong electron correlations--superconductivity--correlation methods--hamiltonians--molecular structure--quantum theory--electron-phonon interaction--occupation factors--strong electron correlations--oxide superconductors
Аннотация: Electron-phonon interaction in cuprate oxides is consistently determined from realistic multi band p-d model in strong correlations limit. We consider the momenta dependence matrix elements of the EPI for modes which most coupled to electrons and analyze a possible mechanism of kink formation. By unitary transformation we obtain an effective low-energy single-band Hamiltonian that includes only electron-electron interactions renormalized by the electron-phonon coupling and depends on occupation factors. (c) 2006 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Ovchinnikov S. G., Gavrichkov V. A., Nekrasov I. A., Pchelkina Z. V., Anisimov V. I.
Заглавие : Application of the new LDA plus GTB method for the band structure calculation of n-type cuprates
Разночтения заглавия :авие SCOPUS: Application of the new LDA+GTB method for the band structure calculation of n-type cuprates
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P459-460. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.340
Примечания : Cited References: 11
Предметные рубрики: SUPERCONDUCTIVITY
PARAMETERS
DENSITY
Ключевые слова (''Своб.индексиров.''): strongly correlated electron systems--superconductivity--n-type cuprates--n-type cuprates--strongly correlated electron systems--superconductivity--electronic structure--hamiltonians--mathematical models--oxide superconductors--perturbation techniques--intercluster hopping--n-type cuprates--strongly correlated electron systems--band structure
Аннотация: A novel hybrid scheme is proposed and applied for band structure calculations of undoped n-type cuprate Nd2CuO4. The ab initio LDA calculation is used to obtain single electron and Coulomb parameters of the multiband Hubbard-type model. In strong correlation regime the electronic structure within this model is calculated by the generalized tight-binding (GTB) method, that combines the exact diagonalization of the model Hamiltonian for a small cluster with perturbation treatment of the intercluster hopping and interactions. For Nd2CuO4, this scheme results in charge transfer insulator with value of the gap and band dispersion in agreement to the experimental data. (c) 2006 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : VALKOV V. V.
Заглавие : UNITARY TRANSFORMATIONS OF THE GROUP U(N) AND DIAGONALIZATION OF MULTILEVEL HAMILTONIANS
Место публикации : Theor. Math. Phys.: PLENUM PUBL CORP, 1988. - Vol. 76, Is. 1. - P766-772. - ISSN 0040-5779, DOI 10.1007/BF01029435
Примечания : Cited References: 20
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Petrakovskii G. A., Ryabinkina L. I., Abramova G. M., Kiselev N. I., Romanova O. B.
Заглавие : Influence of magnetic ordering on the resistivity anisotropy of alpha-MnS single crystal
Разночтения заглавия :авие SCOPUS: Influence of magnetic ordering on the resistivity anisotropy of α-MnS single crystal; авие SCOPUS: Influence of magnetic ordering on the resistivity anisotropy of ?-MnS single crystal
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2004. - Vol. 129, Is. 3. - P195-197. - ISSN 0038-1098, DOI 10.1016/j.ssc.2003.09.028; Solid State Commun. - 2004. - Vol. 129, Is. 3. - P195-197. - Вариант Sopus
Примечания : Cited References: 7
Ключевые слова (''Своб.индексиров.''): 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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Rotter I., Sadreev A. F.
Заглавие : Phase rigidity and avoided level crossings in the complex energy plane
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2006. - Vol. 74, Is. 5. - Ст.56204. - ISSN 1539-3755, DOI 10.1103/PhysRevE.74.056204
Примечания : Cited References: 40
Предметные рубрики: OPEN QUANTUM-SYSTEMS
FANO RESONANCES
S-MATRIX
DOT
CONTINUUM
TRANSMISSION
COHERENCE
TRANSPORT
BILLIARDS
PROBE
Ключевые слова (''Своб.индексиров.''): eigenvalues and eigenfunctions--hamiltonians--resonance--rigidity--semiconductor quantum dots--biorthogonal eigenfunctions--open quantum system--phase rigidity--quantum theory
Аннотация: We consider the effective Hamiltonian of an open quantum system, its biorthogonal eigenfunctions phi(lambda), and define the value r(lambda)=(phi(lambda)parallel to phi(lambda))/phi(lambda)parallel to phi(lambda) that characterizes the phase rigidity of the eigenfunctions phi(lambda). In the scenario with avoided level crossings, r(lambda) varies between 1 and 0 due to the mutual influence of neighboring resonances. The variation of r(lambda) is an internal property of an open quantum system. In the literature, the phase rigidity rho of the scattering wave function Psi(E)(C) is considered. Since Psi(E)(C) can be represented in the interior of the system by the phi(lambda), the phase rigidity rho of the Psi(E)(C) is related to the r(lambda) and therefore also to the mutual influence of neighboring resonances. As a consequence, the reduction of the phase rigidity rho to values smaller than 1 should be considered, at least partly, as an internal property of an open quantum system in the overlapping regime. The relation to measurable values such as the transmission through a quantum dot, follows from the fact that the transmission is, in any case, resonant at energies that are determined by the real part of the eigenvalues of the effective Hamiltonian. We illustrate the relation between phase rigidity rho and transmission numerically for small open cavities.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Rotter I.
Заглавие : Spectroscopic properties of large open quantum-chaotic cavities with and without separated time scales
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2006. - Vol. 73, Is. 6. - Ст.66222. - ISSN 1539-3755, DOI 10.1103/PhysRevE.73.066222
Примечания : Cited References: 24
Предметные рубрики: HELMHOLTZ EQUATION
SYSTEMS
DYNAMICS
STATES
TRANSMISSION
BILLIARDS
Ключевые слова (''Своб.индексиров.''): hamiltonians--numerical analysis--phase control--quantum theory--spectroscopic analysis--wave transmission--bunimovich cavity--hamiltonian formalism--phase rigidity--quantum-chaotic cavities--cavity resonators
Аннотация: The spectroscopic properties of an open large Bunimovich cavity are studied numerically in the framework of the effective Hamiltonian formalism. The cavity is opened by attaching two leads to it in four different ways. In some cases, the transmission takes place via standing waves with an intensity that closely follows the profile of the resonances. In other cases, short-lived and long-lived resonance states coexist. The short-lived states cause traveling waves in the transmission while the long-lived ones generate superposed fluctuations. The traveling waves oscillate as a function of energy. They are not localized in the interior of the large chaotic cavity. In all considered cases, the phase rigidity fluctuates with energy. It is mostly near to its maximum value and agrees well with the theoretical value for the two-channel case.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Polukhin D. S.
Заглавие : Effects of cross correlations between inhomogeneities of the parameters of an isotropic medium on the spectrum and damping of elastic waves
Место публикации : J. Exp. Theor. Phys. - NEW YORK: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 2. - С. 345-359. - FEB. - ISSN 1063-7761, DOI 10.1134/S1063776110020184
Примечания : Cited Reference Count: 17. - Гранты: This study was supported in part by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools (grant no. 3818.2008.3) and the Presidium of the Russian Academy of Sciences (program no. 27.1) and performed within the framework of the Federal Target Program (State Contract no. 02.740.11.0220).Финансирующая организация: Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools [3818.2008.3]; Presidium of the Russian Academy of Sciences [27.1]; Federal Target Program [02.740.11.0220]
Ключевые слова (''Своб.индексиров.''): cross correlations--dispersion law--elastic force--inhomogeneities--isotropic medium--negative cross-correlation--physical nature--two parameter--wave spectra--damping--dispersions--elastic waves--hamiltonians--dispersion (waves)
Аннотация: The dispersion and damping laws have been investigated for elastic waves in an isotropic medium with one- and three-dimensional inhomogeneities of the density p(x) of the material and the elastic force constants mu(x) and lambda(x) with allowance for the cross correlations between these inhomogeneities. It has been demonstrated that the positive cross correlations between mu(x) and lambda(x), as well as the negative cross correlations between p(x) and mu(x) or p(x) and lambda(x), lead to an enhancement of the modification of the dispersion law and an increase in the damping of waves. The positive cross correlations between p(x) and mu(x) or p(x) and lambda(x), as well as the negative cross correlations between mu(x) and lambda(x), result in the opposite effects: a weakening of the modification of the dispersion law and a decrease in the damping. An analysis of the results obtained in this paper and in our recent work [15] has made it possible to formulate the general regularity of the effects of cross correlations, irrespective of the physical nature of the waves: the effects of cross correlations between inhomogeneities of any two parameters of the material on the wave spectrum depend on whether both parameters related by the cross correlations belong to the same part of the Hamiltonian (i.e., if they both belong to either the kinetic part or the potential part of the Hamiltonian) or they belong to different parts of the Hamiltonian. The positive cross correlations lead to a greater modification of the dispersion law and to an increase in the damping of waves in the former case and to a decrease in these characteristics in the latter case. Correspondingly, the negative cross correlations in each of these cases result in the opposite effects. This regularity has been explained qualitatively.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R., Korsch H. J., Graefe E. M.
Заглавие : Bloch oscillations of Bose-Einstein condensates: Quantum counterpart of dynamical instability
Место публикации : Phys. Rev. A. - 2009. - Vol. 80, Is. 2. - ISSN 1050-2947, DOI 10.1103/PhysRevA.80.023617
Примечания : Cited Reference Count: 35. - Гранты: We thank D. Witthaut and F. Trimborn for valuable comments. Support from the Deutsche Forschungsgemeinschaft via the Graduiertenkolleg "Nichtlineare Optik und Ultrakurzzeitphysik" is gratefully acknowledged.Финансирующая организация: Deutsche Forschungsgemeinschaft
Предметные рубрики: OPTICAL LATTICE
ATOMS
Ключевые слова (''Своб.индексиров.''): bloch dynamics--bloch oscillations--bogoliubov--bose-einstein condensates--chaotic dynamics--cold atoms--decoherence--dinger equation--dynamical instabilities--equipartition--hubbard--mean-field--optical lattices--quantum counterpart--quasi-one-dimensional--quasimomentum--bose-einstein condensation--hamiltonians--nonlinear equations--steam condensers--stability
Аннотация: We study the Bloch dynamics of a quasi-one-dimensional Bose-Einstein condensate of cold atoms in a tilted optical lattice modeled by a Hamiltonian of Bose-Hubbard type. The corresponding mean-field system described by a discrete nonlinear Schrodinger equation can exhibit dynamical (or modulation) instability due to chaotic dynamics and equipartition over the quasimomentum modes. It is shown that these phenomena are related to Bogoliubov's depletion of the Bose-Einstein condensate and a decoherence of the condensate in the many-particle description. Three types of dynamics are distinguished: (i) decaying oscillations in the region of dynamical instability and (ii) persisting Bloch oscillations or (iii) periodic decay and revivals in the region of stability.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Huang L., Jia B., Pilipchuk A. S., Chiang Y., Huang S., Li J., Shen C., Bulgakov E. N., Deng F., Powell D. A., Cummer S. A., Li Y., Sadreev A. F., Miroshnichenko A. E.
Заглавие : General framework of bound states in the continuum in an open acoustic resonator
Место публикации : Phys. Rev. Appl. - 2022. - Vol. 18, Is. 5. - Ст.054021. - ISSN 23317019 (eISSN), DOI 10.1103/PhysRevApplied.18.054021
Примечания : Cited References: 47. - L.H. and A.E.M. are supported by the Australian Research Council Discovery Project (Grant No. DP200101353) and the UNSW Scientia Fellowship program. Y.K.C. and D.A.P. are supported by the Australian Research Council Discovery Project (Grant No. DP200101708). B.J., S.H., and Y.L. are supported by the National Natural Science Foundation of China (Grant No. 12074286) and the Shanghai Science and Technology Committee (Grant No. 21JC1405600). A.P., E.B., and A.S. are supported by the Russian Science Foundation (Grant No. 22-12-00070)
Аннотация: Bound states in the continuum (BICs) provide a viable way of achieving high-Q resonances in both photonics and acoustics. In this work, we propose a general method of constructing Friedrich-Wintgen (FW) BICs and accidental BICs in a coupled acoustic waveguide-resonator system. We demonstrate that FW BICs can be achieved with arbitrary two degenerate resonances in a closed resonator, regardless of whether they have the same or opposite parity. Moreover, their eigenmode profiles can be arbitrarily engineered by adjusting the position of the attached waveguide. This suggests an effective way of continuously switching the nature of the BICs from FW BICs to symmetry-protected BICs or accidental BICs. Also, such BICs are sustained in the coupled waveguide-resonator system with shapes such as rectangles, ellipses, and rhomboids. These interesting phenomena are well explained by the two-level effective non-Hermitian Hamiltonian, where two strongly coupled degenerate modes play a major role in forming such FW BICs. Additionally, we find that such an open system also supports accidental BICs in geometry space instead of momentum space via tuning the position of the attached waveguide, which is attributed to the quenched coupling between the waveguide and eigenmodes of the closed cavity. Finally, we fabricate a series of three-dimensional coupled resonator waveguides and experimentally verify the existence of FW BICs and accidental BICs by measuring the transmission spectra. Our results complement the current BIC library in acoustics and provide nice routes for designing acoustic devices, such as acoustic absorbers, filters, and sensors.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova M. N., Stanislavchuk T. N., Malkin B. Z., Bezmaternykh L. N.
Заглавие : Optical spectroscopy of PrFe3(BO3)(4): Crystal-field and anisotropic Pr-Fe exchange interactions
Коллективы : Russian Foundation for Basic Research [07-02-01185, 09-02-00930]; Russian Academy of Sciences under the Programs for Basic Research
Разночтения заглавия :авие SCOPUS: Optical spectroscopy of PrFe3 (BO3) 4: Crystal-field and anisotropic Pr-Fe exchange interactions
Место публикации : Phys. Rev. B. - 2009. - Vol. 80, Is. 19. - Ст.195101. - ISSN 1098-0121, DOI 10.1103/PhysRevB.80.195101
Примечания : Cited References: 36. - We thank S. Klimin for useful information concerning the structure of PrFeINF3/INF(BOINF3/INF)INF4/INF and E. Chukalina for participating in some measurements. This work was supported in part by the Russian Foundation for Basic Research (Grants No. 07-02-01185 and No. 09-02-00930) and by the Russian Academy of Sciences under the Programs for Basic Research.
Предметные рубрики: TRIGONAL GDFE3(BO3)(4)
NDFE3(BO3)(4)
DYFE3(BO3)(4)
TRANSITIONS
BORATE
ION
ND
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--crystal field interactions--exchange interactions (electron)--infrared spectra--iron compounds--magnetic susceptibility--magneto-optical effects--paramagnetic materials--praseodymium compounds--spin hamiltonians--visible spectra
Аннотация: High-resolution polarized optical absorption spectra of PrFe3(BO3)(4) in the paramagnetic and antiferromagnetic phases are reported. The measured energies of the crystal-field (CF) levels within the 4f(2) configuration of Pr3+ in the paramagnetic PrFe3(BO3)(4) are described by the CF model that involves the 4f(2)/4f5d and 4f(2)/4f6p configuration interactions. Ordering of Fe spins along the crystalline c axis below T-N=32 K is confirmed by the analysis of the spectra of Er3+ introduced as a probe into PrFe3(BO3)(4). To account for the observed changes in the optical spectra of Pr3+ at temperatures below T-N, in particular, for the shift of the CF levels, splitting of the CF doublets, and the appearance of forbidden lines, the Pr-Fe exchange Hamiltonian defined by seven parameters is considered. The theoretical approach has been tested by calculating the temperature dependence of the magnetic susceptibility. A good agreement between theory and optical and magnetic experimental data is found demonstrating the validity of the model used. The obtained results confirm that the model of the iron dimers inside the spiral chains of Fe3+(O2-)(6) octahedrons introduced by us earlier for NdFe3(BO3)(4) and modified in the present work may serve as a basis for analyzing the low-temperature properties of other rare-earth iron borates.
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