Труды сотрудников института физики

/ S. V. Nikolaev, S. G. Ovchinnikov // J. Exp. Theor. Phys. - 2012. - Vol. 114, Is. 1. - P. 118-131, DOI 10.1134/S1063776111150143. - Cited References: 51. - This study was supported financially by the Russian Foundation for Basic Research (project nos. 10-02-90725-mob_st and 09-02-00127), Program 18.7 of the Presidium of the Russian Academy of Sciences, the Federal Target Program "Personnel" (state contract no. P891), and the integrated project no. 40 of the Siberian Branch of the Russian Academy of Sciences. . - ISSN 1063-7761РУБ Physics, Multidisciplinary

Аннотация: The concentration dependences of the band structure, spectral weight, density of states, and Fermi surface in the paramagnetic state are studied in the Hubbard model within cluster pertubation theory with 2 x 2 clusters. Representation of the Hubbard X operators makes it possible to control conservation of the spectral weight in constructing cluster perturbation theory. The calculated value of the ground-state energy is in good agreement with the results obtained using nonperturbative methods such as the quantum Monte Carlo method, exact diagonalization of a 4 x 4 cluster, and the variational Monte Carlo method. It is shown that in the case of hole doping, the states in the band gap (in-gap states) lie near the top of the lower Hubbard band for large values of U and near the bottom of the upper band for small U. The concentration dependence of the Fermi surface strongly depends on hopping to second (t') and third (t '') neighbors. For parameter values typical of HTSC cuprates, the existence of three concentration regions with different Fermi surfaces is demonstrated. It is shown that broadening of the spectral electron density with an energy resolution typical of contemporary ARPES leads to a pattern of arcs with a length depending on the concentration. Only an order-of-magnitude decrease in the linewidth makes it possible to obtain the true Fermi surface from the spectral density. The kinks associated with strong electron correlations are detected in the dispersion relation below the Fermi level.

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Держатели документа:
[Nikolaev, S. V.
Ovchinnikov, S. G.] Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia
[Nikolaev, S. V.] Dostoevsky State Univ, Omsk 644077, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Николаев, Сергей Викторович

/ A. R. Kolovsky, A. . Buchleitner // Europhys. Lett. - 2004. - Vol. 68, Is. 5. - P. 632-638, DOI 10.1209/epl/i2004-10265-7. - Cited References: 22 . - ISSN 0295-5075РУБ Physics, Multidisciplinary

Аннотация: We present a numerical study of the spectral properties of the 1D Bose-Hubbard model. Unlike the 1D Hubbard model for fermions, this system is found to be non-integrable, and exhibits Wigner-Dyson spectral statistics under suitable conditions.

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Держатели документа:
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН
Max-Planck-Inst. F. Physik K., D-01187 Dresden, Germany
Kirensky Institute of Physics, 660036 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Buchleitner, A.; Коловский, Андрей Радиевич

/ A. R. Kolovsky // Phys. Rev. Lett. - 2003. - Vol. 90, Is. 21. - Ст. 213002, DOI 10.1103/PhysRevLett.90.213002. - Cited References: 19 . - ISSN 0031-9007РУБ Physics, Multidisciplinary

Аннотация: This paper studies Bloch oscillations of ultracold atoms in an optical lattice, in the presence of atom-atom interactions. A new, interaction-induced Bloch period is identified. Analytical results are corroborated by realistic numerical calculations.

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Держатели документа:
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Коловский, Андрей Радиевич

/ S. G. Ovchinnikov, M. M. Korshunov, E. I. Shneyder // J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 5. - Pю. 775-785, DOI 10.1134/S1063776109110077. - Cited References: 71. - The authors thank A. A. Kordyuk for discussion of the results and T. M. Ovchinnikova for technical assistance in data processing.This study was supported by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7), integrated project no. 40 of the Siberian Branch-Ural Division of the Russian academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127). . - ISSN 1063-7761РУБ Physics, Multidisciplinary

Аннотация: Changes in the electronic structure in the normal phase of high-T-c superconductors (HTSCs), viz., layered cuprates, are considered. The results of LDA + GTB calculations of the electron structure and the Fermi surface of La2-xSrxCuO4 one-layer cuprates with allowance for strong correlations are compared with ARPES and quantum oscillations data. Two critical points x(c1) and x(c2) are discovered at which the rearrangement of the Fermi surface takes place. In the vicinity of these points, changes in the thermodynamic properties at low temperatures are determined using the Lifshits ideology concerning 2.5-order quantum phase transitions. A singularity delta(C/T) proportional to (x-x(e))(1/2) in the electron heat capacity agrees well with the available experimental data in the vicinity of x(c1)approximate to 0.15. Sign reversal of the Hall constant upon doping is also considered qualitatively.

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Держатели документа:
[Ovchinnikov, S. G.
Korshunov, M. M.
Shneyder, E. I.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Korshunov, M. M.] Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
[Korshunov, M. M.] Univ Florida, Dept Phys, Gainesville, FL 32611 USA
[Shneyder, E. I.] Reshetnikov Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
Kirenskii Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation
Siberian Federal University, Krasnoyarsk, 660041, Russian Federation
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany
Department of Physics, University of Florida, Gainesville, FL 32611, United States
Reshetnikov Siberian State Aerospace University, Krasnoyarsk, 660014, Russian Federation

Доп.точки доступа:
Korshunov, M. M.; Коршунов, Максим Михайлович; Shneyder, E. I.; Шнейдер, Елена Игоревна; Овчинников, Сергей Геннадьевич; Presidium of the Russian Academy of Sciences [5.7]; Russian academy of Sciences; Russian Foundation for Basic Research [09-02-00127]

/ K. Kudashkin, S. Nikolaev, S. Ovchinnikov // J. Supercond. Nov. Magn. - 2017. - Vol. 30, Is. 1. - P. 103-107, DOI 10.1007/s10948-016-3781-y. - Cited References:16. - This work was supported by RFBR grant 16-02-00098, Government of Krasnoyarsk Territory and RFBR according to the research projects 16-42-243048, 16-42-240511, and 16-42-240769, and the Russian President Grant NSh-7559.2016.2. . - ISSN 1557-1939. - ISSN 1557-1947РУБ Physics, Applied + Physics, Condensed Matter

Аннотация: We study the two-dimensional ultracold Bose gas in optical lattice. We use cluster perturbation theory based on Hubbard X-operators to calculate the spectral function and phase diagram of Bose-Hubbard model which is minimal model to describe behavior of ultracold gases in optical lattices. We have analyzed spectral properties of spinless bosons in a square lattice taking into account the short-range correlation.

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Держатели документа:
Siberian Fed Univ, Krasnoyarsk 660041, Russia.
Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Nikolaev, S. V.; Николаев, Сергей Викторович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; RFBR [16-02-00098, 16-42-243048, 16-42-240511, 16-42-240769]; Government of Krasnoyarsk Territory; Russian President Grant [NSh-7559.2016.2]

/ D. V. Averyanov, A. M. Tokmachev, O. E. Parfenov [et al.] // Appl. Surf. Sci. - 2019. - Vol. 488. - P. 107-114, DOI 10.1016/j.apsusc.2019.05.191. - Cited References: 57. - This work is partially supported by NRC "Kurchatov Institute" (synthesis), the Russian Foundation for Basic Research [grant 19-07-00249] (magnetization measurements), and the Russian Science Foundation [grant 19-19-00009] (transport measurements). The measurements have been carried out using the equipment of the resource centers of electrophysical, laboratory X-ray, and electron microscopy techniques of NRC "Kurchatov Institute". The authors also gratefully acknowledge the beamtime allocation (MA-3167) by the ESRF. . - ISSN 0169-4332. - ISSN 1873-5584РУБ Chemistry, Physical + Materials Science, Coatings & Films + Physics, Applied + Physics, Condensed Matter

Аннотация: Ferromagnetic insulators are widely employed to induce magnetic phenomena in adjacent layers via proximity effect. This approach could make non-magnetic materials (ranging from silicon to graphene) available for spintronic applications. Eu chalcogenides, EuO in particular, are highly efficient spin generators but suffer from low Curie temperatures. Here, experiments aimed at T-C increase in EuO by its integration with the ferromagnetic metal Gd are reported. The epitaxial bilayers Gd/EuO are synthesized on different substrates and characterized by a combination of diffraction and microscopy techniques. Their magnetic structure - established with magnetization and transport measurements as well as element-selective X-ray magnetic circular dichroism study - comprises coupled magnetic orders of EuO and Gd. EuO is robust against proximity effects - its T-C is still low, increased at most by a few tens of K. Nevertheless, the results encourage further studies of proximity-enhanced ferromagnetism to extend the range of applications of ultrathin layers of EuO in spintronics.

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Держатели документа:
Natl Res Ctr Kurchatov Inst, Kurchatov Sq 1, Moscow 123182, Russia.
ESRF, F-38054 Grenoble, France.

Доп.точки доступа:
Averyanov, D. V.; Tokmachev, Andrey M.; Parfenov, Oleg E.; Karateev, Igor A.; Sokolov, I. S.; Taldenkov, Alexander N.; Platunov, M. S.; Платунов, Михаил Сергеевич; Wilhelm, Fabrice; Rogalev, Andrei; Storchak, V. G.; NRC "Kurchatov Institute"; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-07-00249]; Russian Science FoundationRussian Science Foundation (RSF) [19-19-00009]