Труды сотрудников института физики

/ E. I. Shneyder, S. G. Ovchinnikov, A. V. Shnurenko // JETP Letters. - 2012. - Vol. 95, Is. 4. - P. 193-197, DOI 10.1134/S0021364012040078. - Cited References: 44. - This work was supported by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. NSh-1044.2012.2), by the Russian Foundation for Basic Research (project no. 12-02-00040), by the Presidium of the Russian Academy of Sciences (program no. 20 "Quantum Mesoscopic and Disordered Systems"), jointly by the Siberian and Ural Branches of the Russian Academy of Sciences, by Siberian Federal University (project no. s/b S-11), and by the Ministry of Education and Science of the Russian Federation (state contract no. P891, federal program "Human Capital"). E.I.Sh. acknowledges the support of the Dynasty Foundation. . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: The effect of non-Heisenberg four-spin ring exchange on the superconducting transition temperature in strongly correlated electron systems is studied. It is shown that the ring exchange can significantly suppress the contribution of the Heisenberg exchange to superconducting pairing.

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Держатели документа:
[Shneyder, E. I.
Ovchinnikov, S. G.
Shnurenko, A. V.] Russian Acad Sci, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Shnurenko, A. V.; Шнуренко, А. В.; Шнейдер, Елена Игоревна

/ A. E. Ershov [et al.] // Appl. Phys. B. - 2014. - Vol. 115, Is. 4. - P. 547-560, DOI 10.1007/s00340-013-5636-6. - Cited References: 48. - Authors are thankful to Prof. V. A. Markel (University of Pennsylvania) for supplying program codes for realization of the coupled dipole method for polydisperse metal nanoparticle aggregates. This research was supported by the Russian Academy of Sciences under the Grants 24.29, 24.31, III.9.5, 43, SB RAS-SFU (101); Ministry of Education and Science of Russian Federation under Contract 14.B37.21.0457. . - ISSN 0946-2171. - ISSN 1432-0649РУБ Optics + Physics, Applied

Аннотация: We propose an optodynamical model of interaction of pulsed laser radiation with aggregates of spherical metallic nanoparticles embedded into host media. The model takes into account polydispersity of particles, pair interactions between the particles, dissipation of absorbed energy, heating and melting of the metallic core of particles and of their polymer adsorption layers, and heat exchange between electron and ion components of the particle material as well as heat exchange with the interparticle medium. Temperature dependence of the electron relaxation constant of the particle material and the effect of this dependence on interaction of nanoparticles with laser radiation are first taken into consideration. We study in detail light-induced processes in the simplest resonant domains of multiparticle aggregates consisting of two particles of an arbitrary size in aqueous medium. Optical interparticle forces are realized due to the light-induced dipole interaction. The dipole moment of each particle is calculated by the coupled dipole method (with correction for the effect of higher multipoles). We determined the role of various interrelated factors leading to photomodification of resonant domains and found an essential difference in the photomodification mechanisms between polydisperse and monodisperse nanostructures.

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Держатели документа:
Russian Acad Sci, LV Kirenski Inst Phys, Krasnoyarsk 660036, Russia
Russian Acad Sci, Inst Computat Modeling, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660028, Russia

Доп.точки доступа:
Ershov, A. E.; Ершов, Александр Евгеньевич; Gavrilyuk, A. P.; Karpov, S. V.; Карпов, Сергей Васильевич; Semina, P. N.; Семина, Полина Николаевна; Russian Academy of Sciences [24.29, 24.31, III.9.5, 43, SB RAS-SFU (101)]; Ministry of Education and Science of Russian Federation [14.B37.21.0457]

/ A. F. Sadreev, A. S. Pilipchuk // JETP Letters. - 2015. - Vol. 100, Is. 9. - P. 585-590, DOI 10.1134/S0021364014210139. - Cited References:41. - This work was supported by the Russian Foundation for Basic Research(project no. 14-12-00266). . - ISSN 0021. - ISSN 1090-6487. - РУБ Physics, Multidisciplinary

Аннотация: We consider electron transport in a zigzag quantum wire by the effect of finger gate potential. Using a non-Hermitian effective Hamiltonian, we calculate resonance positions and widths to show that the resonance widths are easily governed by the gate potential. In particular, the resonance width can be enforced to be equal to zero, which leads to an electron localization with the Fermi energy embedded in the propagation band of the wire, i.e., the bound state in the continuum (BSC). We show that, for positive values of the potential, a zigzag wire becomes a Fabry-Perot resonator to give rise to BSC too.

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Держатели документа:
Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Krasnoyarsk 660080, Russia.

Доп.точки доступа:
Pilipchuk, A. S.; Пилипчук, Артем Сергеевич; Садреев, Алмаз Фаттахович; Russian Foundation for Basic Research [14-12-00266]

/ V. A. Ignatchenko, D. S. Polukhin // J. Phys. A. - 2016. - Vol. 49, Is. 9. - Ст. 095004, DOI 10.1088/1751-8113/49/9/095004. - Cited References: 43 . - ISSN 1751-8113РУБ Physics, Multidisciplinary + Physics, Mathematical

Аннотация: A self-consistent approximation of a higher level than the standard self-consistent approximation, known in various fields of physics as the Migdal, Kraichnan or Born self-consistent approximation, is derived taking into account both the first and second terms of the series for the vertex function. In contrast to the standard approximation, the new self-consistent approximation is described by a system of two coupled nonlinear integral equations for the self-energy and the vertex function. In addition to all the diagrams with non-intersecting lines of correlation/interaction taken into account by the standard self-consistent approximation, the new approach takes into account in each term of the Green's function expansion a significant number of diagrams with intersections of these lines. Because of this, the shape, linewidth, and amplitude of the resonance peaks of the dynamic susceptibility calculated in this approximation are much closer to the exact values of these characteristics. The advantage of the new self-consistent approach is demonstrated by the example of calculation of the dynamic susceptibility of waves in an inhomogeneous medium. © 2016 IOP Publishing Ltd.

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Доп.точки доступа:
Polukhin, D. S.; Полухин, Дмитрий Сергеевич; Игнатченко, Вальтер Алексеевич

/ S. . Maiti [et al.] // Phys. Rev. B. - 2011. - Vol. 84, Is. 22. - Ст. 224505, DOI 10.1103/PhysRevB.84.224505. - Cited References: 46. - We acknowledge helpful discussions with L. Benfatto, R. Fernandes, W. Hanke, I. Eremin, H. Kontani, K. Kuroki, Y. Matsuda, I. Mazin, R. Prozorov, D. Scalapino, J. Schmalian, Z. Tesanovic, R. Thomale, M. Vavilov, and A. Vorontsov. This work was supported by NSF-DMR-0906953 (S. M. and A. V. C.). Partial support from MPI PKS (Dresden) (S. M. and A. V. C.) and the Humboldt Foundation (A. V. C.) is gratefully acknowledged. T. A. M. acknowledges support from the Center of Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Office of Basic Energy Sciences, US Department of Energy. M. M. K. and P. J. H. acknowledge support from DOE DE-FG02-05ER46236. M. M. K. is grateful for support from RFBR (Grant No. 09-02-00127), Presidium of RAS program N5.7, FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK P891 and GK 16.740.12.0731), and the President of Russia (Grant No. MK-1683.2010.2). . - ISSN 1098-0121РУБ Physics, Condensed Matter

Аннотация: We present a detailed study of the symmetry and structure of the pairing gap in Fe-based superconductors (FeSCs). We treat FeSCs as quasi-2D, decompose the pairing interaction in the XY plane in s-wave and d-wave channels into contributions from scattering between different Fermi surfaces, and analyze how each scattering evolves with doping and input parameters. We verify that each interaction is well approximated by the lowest angular harmonics. We use this simplification to analyze the interplay between the interaction with and without spin-fluctuation components, the origin of the attraction in the s(+/-) and d(x2-y2) channels, the competition between them, the angular dependence of the s(+/-) gaps along the electron Fermi surface, the conditions under which the s(+/-) gap develops nodes, and the origin of superconductivity in heavily electron-or hole-doped systems, when only Fermi surfaces of one type are present. We also discuss the relation between RPA and RG approaches for FeSCs.

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Держатели документа:
[Maiti, S.
Chubukov, A. V.] Univ Wisconsin, Dept Phys, Madison, WI 53706 USA
[Korshunov, M. M.
Hirschfeld, P. J.] Univ Florida, Dept Phys, Gainesville, FL 32611 USA
[Korshunov, M. M.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Korshunov, M. M.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Maier, T. A.] Oak Ridge Natl Lab, Comp Sci & Math Div, Oak Ridge, TN 37831 USA
[Maier, T. A.] Oak Ridge Natl Lab, Ctr Nanophase Mat Sci, Oak Ridge, TN 37831 USA
ИФ СО РАН
Department of Physics, University of Wisconsin, Madison, WI 53706, United States
Department of Physics, University of Florida, Gainesville, FL 32611, United States
L. V. Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Siberian Federal University, Svobodny Prospect 79, 660041 Krasnoyarsk, Russian Federation
Computer Science and Mathematics Division, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States

Доп.точки доступа:
Maiti, S.; Korshunov, M. M.; Коршунов, Максим Михайлович; Maier, T. A.; Hirschfeld, P. J.; Chubukov, A. V.

/ E. . Bulgakov, A. . Sadreev // Phys. Rev. B. - 2011. - Vol. 83, Is. 23. - Ст. 235321, DOI 10.1103/PhysRevB.83.235321. - Cited References: 61 . - ISSN 1098-0121РУБ Physics, Condensed Matter

Аннотация: We consider mechanisms of formation of the bound states in the continuum in open rectangular quantum dots with variable width. Because of symmetry there might be bound states in the continuum (BSCs) embedded into one, two, and three continua because of the symmetry of system. These BSCs arise for selected values of the width. We show numerically that the BSCs can be excited for transmission of wave packets if the quantum dot width is varied in time and reaches these selected values of dot width. Moreover, we consider numerically a decay process of different eigenstates in the closed quantum dot to show that some of them trap in the BSC after the quantum dot is opened.

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Держатели документа:
[Bulgakov, Evgeny
Sadreev, Almas] LV Kirenskii Inst Phys, RU-660036 Krasnoyarsk, Russia
[Bulgakov, Evgeny] Siberian State Aerosp Univ, Krasnoyarsk, Russia
ИФ СО РАН
Kirensky Institute of Physics, RU-660036, Krasnoyarsk, Russian Federation
Siberian State Aerospace University, Krasnoyarsk Rabochii, 31, Krasnoyarsk, Russian Federation

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

/ I. A. Makarov, S. G. Ovchinnikov // JETP Letters. - 2011. - Vol. 93, Is. 6. - P. 339-343, DOI 10.1134/S0021364011060063. - Cited References: 27. - This work was supported by the Presidium of the Russian Academy of Sciences (program no. 18.7 "Quantum Physics of Condensed Matter"), by the Siberian and Ural Branches of the Russian Academy of Sciences (joint project no. 40), by the Russian Foundation for Basic Research (project no. 09-02-00127), by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. MK-1683.2010.2), and by the Ministry of Education and Science of the Russian Federation (project no. GK P891, federal program "Scientific and Pedagogical Personnel of Innovative Russia"). . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: It is well known that the superconducting transition temperature of high-T-c cuprates depends on the number of CuO2 planes in the unit cell. The multilayer structure implies the possibility of interlayer hopping. Under the assumption that the interlayer hopping can be specified by the parameter t(perpendicular to)(k) = t(perpendicular to)(cos(k(x)) - cos(k(y)))(2), the quasiparticle excitation spectrum for the bilayer cuprate in the superconducting state has been determined in the framework of the t - t' - t '' - t(perpendicular to) - J* model using the generalized mean-field approximation. It turns out that the interlayer hoppings does not create any additional mechanism of the Cooper paring and does not lead to an increase in T-c. The splitting of the upper Hubbard quasiparticle band attributed to the interlayer hoppings is manifested as two peaks in the doping dependence of the superconducting transition temperature at temperatures below the maximum T-c value for a single-layer cuprate. It has been found that antiferromagnetic interlayer correlations suppress the interlayer splitting. This probably leads to the common doping dependence of T-c for both single-layer and bilayer cuprates.

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Держатели документа:
[Makarov, I. A.
Ovchinnikov, S. G.] Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia
[Ovchinnikov, S. G.] Reshetnev Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russian Federation
Reshetnev Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Макаров, Илья Анатольевич

/ E. N. Bulgakov, A. F. Sadreev // Phys. Rev. B. - 2008. - Vol. 78, Is. 7. - Ст. 75105, DOI 10.1103/PhysRevB.78.075105. - Cited References: 53 . - ISSN 1098-0121РУБ Physics, Condensed Matter

Аннотация: Photonic crystal with defect layer forms directed continuum for electromagnetic waves. Defect rods in the vicinity of the defect layer interact with the continuum and give rise to scattering of ingoing waves. We derive quantum-mechanical analog of the non-Hermitian Hamiltonian of the open system with complex eigenvalues, which describes a scattering of electromagnetic waves by the defect rods. In this formalism a bound state in the continuum (BIC) can be easily found by the condition that one of the complex eigenvalues becomes real for variation of dielectric constant of the defect rods. We numerically find BICs with discrete frequencies belong to the continuum for different arrangements of the defects and show that they are localized around the defects.

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Держатели документа:
[Bulgakov, Evgeny N.
Sadreev, Almas F.] Russian Acad Sci, Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН
Institute of Physics, Academy of Sciences, 660036 Krasnoyarsk, Russian Federation

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

/ V. A. Gavrichkov, S. G. Ovchinnikov // Phys. Solid State. - 2008. - Vol. 50, Is. 6. - P. 1081-1086, DOI 10.1134/S1063783408060140. - Cited References: 12. - This study was supported by the Integration Project of the Siberian Branch–Ural Branch of the Russian Academy of Sciences (project. no. 74), the Russian Academy of Sciences, the Presidium of the Russian Academy of Sciences within the program “Quantum Macrophysics,” and the Russian Foundation for Basic Research (project nos. 06-02-90537-BNTS and 07-02-00226) . - ISSN 1063-7834РУБ Physics, Condensed Matter

Аннотация: The effective spin Hamiltonian for undoped cuprates is constructed in the framework of the realistic multiband p-d model with the parameters calculated from first principles. The exchange interaction parameter is defined as the sum of the antiferromagnetic and ferromagnetic contributions, which are determined by the two-hole triplet terms. The ferromagnetic and antiferromagnetic contributions of the excited terms compensate each other to a large extent. It is shown that the antiferromagnetic contribution of the two-hole ground singlet (1)A(1g) to the exchange interaction is dominant.

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Держатели документа:
[Gavrichkov, V. A.
Ovchinnikov, S. G.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Gavrichkov, V. A.
Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660062, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russian Federation
Siberian Federal University, Svobodnyi pr. 79, Krasnoyarsk, 660062, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Гавричков, Владимир Александрович

/ M. M. Korshunov, S. G. Ovchinnikov, A. V. Sherman // JETP Letters. - 2004. - Vol. 80, Is. 1. - P. 39-43, DOI 10.1134/1.1800212. - Cited References: 32 . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: An effective low-energy Hamiltonian is derived from a microscopic multiband p-d model in the regime of strong electron correlations. The parameters of the p-d model are determined by comparison with the ARPES data for undoped Nd2CuO4. The Hamiltonian is the t-J* model in which hopping and exchange slowly decay with distance and are taken into account up to the fifth coordination sphere. The quasiparticle band structure is calculated as a function of the doping concentration with regard to short-range magnetic order, and the superconductivity theory with the spin-fluctuation pairing mechanism is constructed. Assuming that the parameters of the model do not depend on the doping level, we obtained quantitative agreement with the properties observed experimentally for the normal and superconducting phases without introducing fitting parameters. (C) 2004 MAIK "Nauka / Interperiodica".

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Div, Krasnoyarsk 660036, Russia
Univ Tartu, Inst Phys, EE-51014 Tartu, Estonia
ИФ СО РАН
Kirenskii Institute of Physics, Siberian Division, Russian Academy of Sciences, Krasnoyarsk, Akademgorodok, 660036, Russian Federation
Institute of Physics, University of Tartu, Tartu, 51014, Estonia

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

/ E. N. Bulgakov [et al.] // JETP Letters. - 2006. - Vol. 84, Is. 8. - P. 430-435, DOI 10.1134/S0021364006200057. - Cited References: 33 . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: Using the formalism of the effective Hamiltonian, we consider bound states in a continuum (BIC). They are nonhermitian effective Hamiltonian eigenstates that have real eigenvalues. It is shown that BICs are orthogonal to open channels of the leads, i.e., disconnected from the continuum. As a result, BICs can be superposed to a transport solution with an arbitrary coefficient and exist in a propagation band. The one-dimensional Aharonov-Bohm rings that are opened by attaching single-channel leads to them allow exact consideration of BICs. BICs occur at discrete values of the energy and magnetic flux; however, it's realization strongly depends on the way to the BIC point.

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Держатели документа:
Russian Acad Sci, Inst Phys, Krasnoyarsk 660036, Russia
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
ИФ СО РАН
Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany

Доп.точки доступа:
Bulgakov, E. N.; Булгаков, Евгений Николаевич; Pichugin, K. N.; Пичугин, Константин Николаевич; Sadreev, A. F.; Садреев, Алмаз Фаттахович; Rotter, I.

/ A. F. Sadreev, E. N. Bulgakov, I. . Rotter // Phys. Rev. B. - 2006. - Vol. 73, Is. 23. - Ст. 235342, DOI 10.1103/PhysRevB.73.235342. - Cited References: 24 . - ISSN 1098-0121РУБ Physics, Condensed Matter

Аннотация: We show the existence of bound states in the continuum (BICs) in quantum billiards (QBs) that are opened by attaching single-channel leads to them. They may be observed by varying an external parameter continuously, e.g., the shape of the QB. At some values of the parameter, resonance states with vanishing decay width (the BICs) occur. They are localized almost completely in the interior of the closed system. The phenomenon is shown analytically to exist in the simplest case of a two level QB and is complemented by numerical calculations for a real QB.

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Держатели документа:
Acad Sci, Inst Phys, Krasnoyarsk 660036, Russia
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
ИФ СО РАН
Institute of Physics, Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany

Доп.точки доступа:
Bulgakov, E. N.; Булгаков, Евгений Николаевич; Rotter, I.; Садреев, Алмаз Фаттахович

/ E. I. Shneyder, S. G. Ovchinnikov // JETP Letters. - 2006. - Vol. 83, Is. 9. - P. 394-398, DOI 10.1134/S0021364006090062. - Cited References: 22 . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: The t-t'-t"-J* model of electrons interacting with three phonon modes (breathing, apical breathing, and buckling) is considered. The wave-vector dependence of the matrix elements of the electron-phonon interaction leads to opposite contributions to the pairing potential with the d(x2-y2) symmetry: the buckling mode facilitates electron pairing, while the breathing mode suppresses it. As a result, the critical temperature of La2-xSrxCuO4 that is associated with the magnetic mechanism is lowered when phonons are taken into account.

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Держатели документа:
Russian Acad Sci, Kirenskii Inst Phys, Siberian Div, Krasnoyarsk 660036, Russia
Krasnoyarsk State Univ, Krasnoyarsk 660062, Russia
ИФ СО РАН

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Шнейдер, Елена Игоревна

/ I. A. Makarov, S. G. Ovchinnikov, E. I. Shneider // JETP Letters. - 2009. - Vol. 89, Is. 12. - P. 632-637, DOI 10.1134/S002136400912008X. - Cited References: 19. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00127), the Siberian Branch and the Ural Division, Russian Academy of Sciences (integration project no. 40), and the Presidium of the Russian Academy of Sciences (program no. 5.7). . - ISSN 0021-3640РУБ Physics, Multidisciplinary

Аннотация: The effect of a high magnetic field on the electronic structure of HTSC cuprates is considered. The study is performed in the t-t'-taEuro(3)-J* model, and the high magnetic field effect is taken into account not only as the Zeeman splitting of the one-electron levels, but also in the occupation numbers of the states with different spin projections and in the formation of the spin correlation functions. The field is assumed to be high enough to align all of the spins along the field. As a result, the Fermi surface reconstruction is obtained from four hole pockets about the nodal point (pi/2, pi/2) in the paramagnetic phase to a large hole pocket about the point (pi, pi) in the ferromagnetic phase. As the magnetic field strength decreases, a number of quantum phase transitions are revealed; they are manifested in the changed Fermi surface topology. The Fermi surface reconstruction with a decreasing field is qualitatively the same as that with an increasing doping degree in the absence of a magnetic field.

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Держатели документа:
[Makarov, I. A.
Ovchinnikov, S. G.
Shneider, E. I.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Shneider, E. I.] Reshetnev 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
Reshetnev Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Shneider, E. I.; Шнейдер, Елена Игоревна; Макаров, Илья Анатольевич; Russian Foundation for Basic Research [09-02-00127]; Siberian Branch and the Ural Division, Russian Academy of Sciences [40]; Presidium of the Russian Academy of Sciences [5.7]

/ V. A. Gavrichkov, S. I. Polukeev, S. G. Ovchinnikov // Phys. Rev. B. - 2020. - Vol. 101, Is. 9. - Ст. 094409, DOI 10.1103/PhysRevB.101.094409. - Cited References: 65. - We acknowledge the support of the Russian Science Foundation through Grant No. 18-12-00022 . - ISSN 2469-9950. - ISSN 2469-9969РУБ Materials Science, Multidisciplinary + Physics, Applied + Physics, Condensed Matter

Аннотация: We derived simple rules for the sign of 180° superexchange interaction based on the multielectron calculations of the superexchange interaction in the transition metal oxides that are valid both below and above spin crossover under high pressure. The superexchange interaction between two cations in dn configurations is given by a sum of partial contributions related to the electron-hole virtual excitations to the different states of the dn+1 and dn−1 configurations. Using these rules, we have analyzed the sign of the 180° superexchange interaction of a number of oxides with magnetic cations in electron configurations from d2 until d8: the iron, cobalt, chromium, nickel, copper, and manganese oxides with increasing pressure. The most interesting result concerns the magnetic state of cobalt and nickel oxides CoO, Ni2O3 and also La2CoO4, LaNiO3 isostructural to well-known high-TC and colossal magnetoresistance materials. These oxides have a spin 12 at the high pressure. Change of the interaction from antiferromagnetic below spin crossover to ferromagnetic above spin crossover is predicted for oxide materials with cations in d5(FeBO3) and d7(CoO) configurations, while for materials with the other dn configurations spin crossover under high pressure does not change the sign of the 180∘ superexchange interaction.

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Держатели документа:
Kirensky Inst Phys, Akadeingorodok 50,Bld 38, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Polukeev, S. I.; Полукеев, Семен Игоревич; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Гавричков, Владимир Александрович; Russian Science FoundationRussian Science Foundation (RSF) [18-12-00022]

/ V. A. Ignatchenko, D. S. Polukhin // J. Exp. Theor. Phys. - 2020. - Vol. 130, Is. 3. - P. 358-369, DOI 10.1134/S1063776120010033. - Cited References: 37 . - ISSN 1063-7761. - ISSN 1090-6509
Аннотация: The crossing resonance of two wavefields m(x, t) and u(x, t) of different natures in an inhomogeneous medium with zero mean value of the coupling parameter η between fields has been studied. The stages of formation of the fine structure of the crossing resonance have been analyzed. It has been shown within the model of independent crystallites that the removal of the degeneracy of eigenfrequencies of these fields at the crossing resonance point has a threshold character in the coupling parameter and occurs under the condition η ηc, where ηc = |Γu – Γm|/2, Γu and Γm are the relaxation parameters of the corresponding wavefields. At η ηc, each random implementation of the Green’s functions G~′′mm and G~′′uu of wavefields has the form of two resonance peaks with the same half-width (Γu + Γm)/2 spaced by the interval 2η; this form is standard for crossing resonances. At η ηc, the functions G~′′mm and G~′′uu are different: if Γu Γm, the function G~′′mm has the form of a narrow resonance peak at ω = ωr, whereas the function G~′′uu has the form of a broader resonance peak split at the top by a narrow antiresonance. Averaging over regions where η ηc leads to the formation of a broad resonance with a resonance line half-width of about η2〉1/2 on the both averaged Green’s functions, which is due to the stochastic distribution of resonance frequencies. Averaging over regions where η ηc results in the sharpening of a resonance peak on the function G′′mm and an antiresonance peak on the function G′′uu at the same frequency ω vu at the first and second crossing points, respectively.

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Russian Acad Sci, Siberian Branch, Krasnoyarsk Sci Ctr, Kirensky Inst Phys,Fed Res Ctr, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Polukhin, D. S.; Полухин, Дмитрий Сергеевич; Игнатченко, Вальтер Алексеевич