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1.


   
    Features in the resonance behavior of magnetization in arrays of triangular and square nanodots / V. A. Orlov, R. Y. Rudenko, V. S. Prokopenko, I. N. Orlova // J. Sib. Fed. Univ. Math. Phys. - 2021. - Vol. 14, Is. 5. - P. 611-623 ; Журн. СФУ. Матем. и физика, DOI 10.17516/1997-1397-2021-14-5-611-623. - Cited References: 23. - This study was supported by the Russian Foundation for Basic Research, project no. 20-02-00696 . - ISSN 1997-1397. - ISSN 2313-6022
   Перевод заглавия: Особенности резонансного поведения намагниченности в массивах треугольных и квадратных наноточек
РУБ Mathematics
Рубрики:
VORTEX STATE
   DYNAMICS

   MOTION

   EXCITATIONS

Кл.слова (ненормированные):
differential equation -- Cauchy problem -- split -- stability -- convergence -- дифференциальные уравнения -- задача Коши -- расщепление -- устойчивость -- сходимость
Аннотация: Collective modes of the gyrotropic motion of a magnetic vortex core in ordered arrays of triangular and square ferromagnetic film nanodots have been theoretically investigated. The dispersion relations have been derived. The dipole-dipole interaction of the magnetic moments of the magnetic vortex cores of elements has been taken into account in the approximation of a small shift from the equilibrium position. It is shown that the effective rigidity of the magnetic subsystem of triangular elements is noticeably higher than that of the subsystem of square elements of the same linear sizes. The potential application of the polygonal film nanodisks as nanoscalpels for noninvasive tumor cell surgery is discussed.
Теоретически исследуются коллективные моды гиротропного движения ядра магнитного вихря в упорядоченных массивах ферромагнитных пленочных наноточек треугольной и квадратной форм. Получены дисперсионные соотношения. Учитывается диполь-дипольное взаимодействие магнитных моментов ядер магнитных вихрей элементов в приближении малого смещения от положения равновесия. Показано, что эффективная жесткость магнитной подсистемы в треугольных элементах заметно больше, чем в квадратных при одинаковых линейных размерах. Обсуждается перспектива использования пленочных нанодисков-многоугольников в качестве "наноскальпелей" для неинвазивной клеточной хирургии опухолей.

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Держатели документа:
Siberian Fed Univ, Krasnoyarsk, Russia.
Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk, Russia.
Krasnoyarsk State Pedag Univ, Krasnoyarsk, Russia.

Доп.точки доступа:
Orlov, V. A.; Орлов, Виталий Александрович; Rudenko, Roman Yu; Prokopenko, Vladimir S.; Orlova, Irina N.; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [20-02-00696]

}
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2.


   
    Low-temperature spin dynamics in the TmFeO3 orthoferrite with a non-Kramers ion / S. A. Skorobogatov, S. E. Nikitin, K. A. Shaykhutdinov [et al.] // Phys. Rev. B. - 2020. - Vol. 101, Is. 1. - Ст. 014432, DOI 10.1103/PhysRevB.101.014432. - Cited References: 41. - We thank A. Sukhanov for stimulating discussions and D. Abernathy for support with data acquisition. This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory. S.E.N. acknowledges support from the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). Laue x-ray diffraction measurements were conducted at the Center for Nanophase Materials Sciences (CNMS) (CNMS2019-R18) at Oak Ridge National Laboratory (ORNL), which is a DOE Office of Science User Facility . - ISSN 2469-9950. - ISSN 2469-9969
РУБ Materials Science, Multidisciplinary + Physics, Applied + Physics, Condensed Matter
Рубрики:
NEUTRON-SCATTERING
   REORIENTATION

   VISUALIZATION

   EXCITATIONS

   SOFTWARE

Аннотация: We investigate the magnetic dynamics of the orthorhombic perovskite TmFeO3 at low temperatures, below the spin reorientation transition at TSR≈80 K, by means of time-of-flight neutron spectroscopy. We find that the magnetic excitation spectrum combines two emergent collective modes associated with different magnetic sublattices. The Fe subsystem orders below TN∼632 K into a canted antiferromagnetic structure and exhibits sharp, high-energy magnon excitations. We describe them using linear spin-wave theory, and reveal a pronounced anisotropy between in- and out-of-plane exchange interactions, which was mainly neglected in previous reports on the spin dynamics in orthoferrites. At lower energies, we find two crystalline electrical field (CEF) excitations of Tm3+ ions at energies of ∼2 and 5 meV. In contrast to the sister compound YbFeO3, where the Yb3+ ions form quasi-one-dimensional chains along the c axis, the Tm excitations show dispersion along both directions in the (0KL) scattering plane. Analysis of the neutron scattering polarization factor reveals a longitudinal polarization of the 2 meV excitation. To evaluate the effect of the CEF on the Tm3+ ions, we perform point-charge model calculations, and their results quantitatively capture the main features of Tm single-ion physics, such as energies, intensities, and polarization of the CEF transitions, and the type of magnetic anisotropy.

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Держатели документа:
Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.
Siberian Fed Univ, Inst Engn Phys & Radioelect, Dept Solid State Phys & Nanotechnol, Krasnoyarsk 660041, Russia.
Max Planck Inst Chem Phys Solids, D-01187 Dresden, Germany.
Tech Univ Dresden, Inst Festkorper & Mat Phys, D-01069 Dresden, Germany.
Oak Ridge Natl Lab, Neutron Technol Div, POB 2009, Oak Ridge, TN 37831 USA.
Oak Ridge Natl Lab, Neutron Scattering Div, POB 2009, Oak Ridge, TN 37831 USA.
Paul Scherrer Inst, Lab Multiscale Mat Expt, CH-5232 Villigen, Switzerland.

Доп.точки доступа:
Skorobogatov, S. A.; Скоробогатов, Станислав Алексеевич; Nikitin, S. E.; Shaykhutdinov, K. A.; Шайхутдинов, Кирилл Александрович; Balaev, A. D.; Балаев, Александр Дмитриевич; Terentjev, K. Yu.; Терентьев, Константин Юрьевич; Ehlers, G.; Sala, G.; Pomjakushina, E., V; Conder, K.; Podlesnyak, A.; International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM)
}
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3.


   
    Stability of the d-wave pairing with respect to the intersite Coulomb repulsion in cuprate superconductors / V. V. Val'kov [et al.] // J. Magn. Magn. Mater. - 2017. - Vol. 440. - P. 123-126, DOI 10.1016/j.jmmm.2016.12.090. - Cited References: 23. - The work was supported by the Siberian Branch of Russian Academy of Sciences (project no. 0358-2015-0002, Complex Program II.2P), the Russian Foundation for Basic Research (RFBR) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (projects nos. 16-42-240435 and 16-42-243057). The work of A.F.B. was funded by RFBR (project no. 16-02-00304). The work of M.M.K. was supported by grant of the President of the Russian Federation (project MK-1398.2017.2). . - ISSN 0304-8853
РУБ Materials Science, Multidisciplinary + Physics, Condensed Matter
Рубрики:
HUBBARD-MODEL
   EXCITATIONS

Кл.слова (ненормированные):
Cuprate superconductors -- Spin-fermion model -- Intersite Coulomb repulsion
Аннотация: Within the spin-fermion model for cuprate superconductors, the influence of the intersite Coulomb interactions V2 and V′2V′2 between holes located at the next-nearest-neighbor oxygen ions of CuO2 plane on the implementation of the dx2−y2dx2−y2-wave pairing is studied. It is shown that d-wave pairing can be suppressed only for unphysically large values of V2 and V′2V′2.
В рамках спин-фермионной модели для купратных сверхпроводников изучено влияние межузельных кулоновских отталкиваний V2 и V2' между дырками, находящимися на следующих за ближайшими ионах кислорода CuO2-плоскости, на реализацию сверхпроводящего dx2y2-спаривания. Показано, что d-спаривание подавляется только при нефизически больших значениях параметров V2 и V2'.

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Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Korovushkin, M. M.; Коровушкин, Максим Михайлович; Barabanov, A. F.; Euro-Asian Symposium "Trends in MAGnetism"(6 ; 2016 ; Aug. ; 15-19 ; Krasnoyarsk); "Trends in MAGnetism", Euro-Asian Symposium(6 ; 2016 ; Aug. ; 15-19 ; Krasnoyarsk); Институт физики им. Л.В. Киренского Сибирского отделения РАН
}
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4.


   
    Magnetic ground state of the Ising-like antiferromagnet DyScO3 / L. S. Wu [et al.] // Phys. Rev. B. - 2017. - Vol. 96, Is. 14. - Ст. 144407, DOI 10.1103/PhysRevB.96.144407. - Cited References:37. - We thank J. M. Sheng and Q. Zhang for the help with the neutron data refinement. We would like to thank A. Christianson, I. Zaliznyak, M. Mourigal, Z. T. Wang, and C. Batista for useful discussions. The research at the Spallation Neutron Source (ORNL) is supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy (DOE). Research supported in part by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. This work was partly supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Science and Engineering Division. . - ISSN 2469-9950. - ISSN 2469-9969
РУБ Physics, Condensed Matter
Рубрики:
THIN-FILMS
   FERROELECTRICITY

   VISUALIZATION

   EXCITATIONS

Аннотация: We report on the low-temperature magnetic properties of the DyScO3 perovskite, which were characterized by means of single crystal and powder neutron scattering, and by magnetization measurements. Below TN = 3.15 K, Dy3+ moments form an antiferromagnetic structure with an easy axis of magnetization lying in the ab plane. The magnetic moments are inclined at an angle of ∼ +/- 28 degrees to the b axis. We show that the ground-state Kramers doublet of Dy3+ is made up of primarily |+/- 15/2 ⟩ eigenvectors and well separated by a crystal field from the first excited state at E1 = 24.9 meV. This leads to an extreme Ising single-ion anisotropy, M⊥/M∥∼ 0.05. The transverse magnetic fluctuations, which are proportional to M⊥2/M∥2, are suppressed, and only moment fluctuations along the local Ising direction are allowed. We also found that the Dy-Dy dipolar interactions along the crystallographic c axis are two to four times larger than in-plane interactions.

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Держатели документа:
Oak Ridge Natl Lab, Quantum Condensed Matter Div, Oak Ridge, TN 37831 USA.
Max Planck Inst Chem Phys Solids, Nothnitzer Str 40, D-01187 Dresden, Germany.
Tech Univ Dresden, Inst Festkorper & Mat Phys, D-01069 Dresden, Germany.
Oak Ridge Natl Lab, Chem & Engn Mat Div, Oak Ridge, TN 37831 USA.
Fed Res Ctr SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.
Oak Ridge Natl Lab, Neutron Data Anal & Visualizat Div, Oak Ridge, TN 37831 USA.
Oak Ridge Natl Lab, Ctr Nanophase Mat Sci, Oak Ridge, TN 37831 USA.
Oak Ridge Natl Lab, Chem Sci Div, Oak Ridge, TN 37831 USA.
Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA.

Доп.точки доступа:
Wu, L. S.; Nikitin, S. E.; Frontzek, M.; Kolesnikov, A. I.; Ehlers, G.; Lumsden, M. D.; Shaykhutdinov, K. A.; Шайхутдинов, Кирилл Александрович; Guo, E. -J.; Savici, A. T.; Gai, Z.; Sefat, A. S.; Podlesnyak, A.; Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy (DOE); Laboratory Directed Research and Development Program of Oak Ridge National Laboratory; U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Science and Engineering Division
}
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5.


    Val'kov, V. V.
    Dynamicalmagnetic susceptibility in the spin-fermion model for cuprate superconductors / V. V. Val'kov, D. M. Dzebisashvili // Theor. Math. Phys. - 2017. - Vol. 193, Is. 3. - P. 1853-1864, DOI 10.1134/S004057791712011X. - Cited References:35. - This research was supported by the Russian Foundation for Basic Research (Grant No. 16-02-00073), the Administration of Krasnoyarsk Kray and the Krasnoyarsk Kray Foundation for Scientific and Technical Progress (Grant No. 16-42-240435), and the complex program No. II.2P of the Siberian Branch of the Russian Academy of Sciences (Grant No. 0356-2015-0405). . - ISSN 0040-5779. - ISSN 1573-9333
РУБ Physics, Multidisciplinary + Physics, Mathematical
Рубрики:
T-J MODEL
   LONG-RANGE-ORDER

   POLARON

   CUO2

   EXCITATIONS

   LATTICE

   WAVE

Кл.слова (ненормированные):
high-temperature conductor -- spin-fermion model -- magnetic susceptibility -- spin polaron
Аннотация: Using the method of diagram techniques for the spin and Fermi operators in the framework of the SU(2)-invariant spin-fermion model of the electron structure of the CuO2plane of copper oxides, we obtain an exact representation of the Matsubara Green’s function D⊥(k, iω m ) of the subsystem of localized spins. This representation includes the Larkin mass operator ΣL(k, iω m ) and the strength and polarization operators P(k, iω m ) and Π(k, iω m ). The calculation in the one-loop approximation of the mass and strength operators for the Heisenberg spin system in the quantum spin-liquid state allows writing the Green’s function D⊥(k, iω m ) explicitly and establishing a relation to the result of Shimahara and Takada. An essential point in the developed approach is taking the spin-polaron nature of the Fermi quasiparticles in the spin-fermion model into account in finding the contribution of oxygen holes to the spin response in terms of the polarization operator Π(k, iω m ).

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Публикация на русском языке Вальков, Валерий Владимирович. Динамическая магнитная восприимчивость в спин-фермионной модели купратных сверхпроводников [Текст] / В. В. Вальков, Д. М. Дзебисашвили // Теор. и мат. физика. - 2017. - Т. 193 Вып. 3. - С. 515-529

Держатели документа:
RAS, Siberian Branch, Fed Res Ctr, Kirensky Inst Phys,KSC, Krasnoyarsk, Russia.
Siberian State Aerosp Univ, Krasnoyarsk, Russia.

Доп.точки доступа:
Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Вальков, Валерий Владимирович; Russian Foundation for Basic Research [16-02-00073]; Krasnoyarsk Kray Foundation for Scientific and Technical Progress [16-42-240435]; Siberian Branch of the Russian Academy of Sciences [II.2P, 0356-2015-0405]; Administration of Krasnoyarsk Kray
}
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6.


    Kuz’min, V. I.
    Influence of varying magnetic order in an external magnetic field on the electronic structure and Fermi surface within the t–J model / V. I. Kuz’min, S. V. Nikolaev, S. G. Ovchinnikov // JETP Letters. - 2016. - Vol. 103, Is. 2. - P. 125-130, DOI 10.1134/S0021364016020089. - Cited References: 46. - This work was supported by the Russian Science Foundation (project no. 14-12-00061). . - ISSN 0021-3640
РУБ Physics, Multidisciplinary
Рубрики:
C copper oxides
   Quantum oscillations

   Cuprate superconductors

   Hubbard-model

   Temperature

   Excitations

   YBa2Cu3OY

   Evolution

   Phase

Аннотация: We investigate the electronic structure of the two-dimensional t–J model in a transverse external static magnetic field with canted long-range magnetic order using cluster perturbation theory. The distribution of the spectral weight in the whole range of fields from zero to ferromagnetic saturation is explored. We demonstrate the possibility of a sharp change in a distribution of spectral weight at the Fermi level associated with the magnetic correlations when varying magnetic field.

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Публикация "на русском языке" Kuz’min V. I. Influence of varying magnetic order in an external magnetic field on the electronic structure and Fermi surface within the t–J model [Текст] / V. I. Kuz’min, S. V. Nikolaev, S. G. Ovchinnikov // Письма в Журн. эксперим. и теор. физ. : Наука, 2016. - Т. 103 Вып. 1-2. - С. 132-137

Держатели документа:
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation
National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, Moscow, Russian Federation

Доп.точки доступа:
Nikolaev, S. V.; Николаев, Сергей Викторович; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Кузьмин, Валерий Ипполитович
}
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7.


    Makarov, I. A.
    Temperature dependence of the electronic structure of La2CuO4 in the multielectron LDA+GTB approach / I. A. Makarov, S. G. Ovchinnikov // J. Exp. Theor. Phys. - 2015. - Vol. 121, Is. 3. - P. 457-464, DOI 10.1134/S1063776115090174. - Cited References: 38. - The work was supported by the Russian Science Foundation (project no. 14-12-00061) . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
Copper oxides
   Model

   Superconductivity

   Excitations

   Instability

   Spectrum

   States

   Order

Аннотация: The band structure of La2CuO4 in antiferromagnetic and paramagnetic phases is calculated at finite temperatures by the multielectron LDA+GTB method. The temperature dependence of the band spectrum and the spectral weight of Hubbard fermions is caused by a change in the occupation numbers of local multielectron spin-split terms in the antiferromagnetic phase. A decrease in the magnetization of the sublattice with temperature gives rise to new bands near the bottom of the conduction band and the top of the valence band. It is shown that the band gap decreases with increasing temperature, but La2CuO4 remains an insulator in the paramagnetic phase as well. These results are consistent with measurements of the red shift of the absorption edge in La2CuO4 with increasing temperature. © 2015, Pleiades Publishing, Inc.

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Публикация на русском языке Макаров, Илья Анатольевич. Температурная зависимость электронной структуры La2CuO4 в многоэлектронном подходе LDA+GTB [Текст] / И. А. Макаров, С. Г. Овчинников // Журн. эксперим. и теор. физ. : Наука, 2015. - Т. 148 Вып. 3. - С. 526-534

Держатели документа:
Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Макаров, Илья Анатольевич
}
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8.


   
    Antiferromagnetic dichroism in a complex multisublattice magnetoelectric CuB2O4 / K. N. Boldyrev [et al.] // Phys. Rev. Lett. - 2015. - Vol. 114, Is. 24. - Ст. 247210, DOI 10.1103/PhysRevLett.114.247210. - Cited References:40. - This study was supported by the Russian Academy of Sciences under the Programs for Basic Research, by the President of the Russian Federation (Grant No. MK-3521.2015.2, K. N. B.), by the Russian Foundation for Basic Research (Grants No. 15-32-20613, K. N. B., and No. 15-02-04222, R. V. P.), and by the Ministry of Education and Science of the Russian Federation (Grant No. 14.B25.0031.25, R. V. P.). . - ISSN 0031. - ISSN 1079-7114
   Перевод заглавия: Антиферромагнитный дихроизм в сложном многоподрешеточном магнетоэлектрике CuB2O4
РУБ Physics, Multidisciplinary
Рубрики:
MAGNETIC SOLITON LATTICE
   COPPER METABORATE

   GYROTROPIC BIREFRINGENCE

   SPECTROSCOPY

   EXCITATIONS

   TRANSITIONS

   CRYSTALS

   Cr2O3

   FIELD

Аннотация: Magnetic control of the crystal chirality was announced by Saito et al. [Phys. Rev. Lett. 101, (2008)] on the ground of experiments in CuB2O4. This claim has raised a sharp dispute in the literature because it seemed to contradict the fundamental symmetry principles. We settle this dispute on the basis of a high-resolution optical spectroscopy study of excitonic transitions in CuB2O4. We find that a large sublattice-sensitive antiferromagnetic linear dichroism (LD) emerges at the Néel temperature TN=21 K and show how it could simulate a “magnetic-field control of the crystal chirality.” We prove that the discovered LD is related microscopically to the magnetic Davydov splitting. This LD is highly sensitive to subtle changes in the spin subsystems, which allowed us to observe a splitting of the phase transition into an incommensurate magnetic phase into two transitions (T∗1=8.5 and T∗2=7.9 K) and to suggest elliptical spiral structures below T∗1, instead of a simple circular helix proposed earlier.
О магнитном контроле кристаллической хиральности сообщил Сайто и др. [Phys. Rev. Lett. 101, 117402 (2008)] на основании экспериментов в CuB2O4. Это требование вызвало резкий спор в литературе, потому что это казалось, противоречат основным принципам симметрии. Мы урегулировать этот спор на основе исследования с помощью оптической спектроскопии высокого разрешения экситонных переходов в CuB2O4. Мы считаем, что большой подрешетко-чувствительный антиферромагнитный линейный дихроизм (LD) возникает при температуре Нееля TN= 21 Kи показываем, как это может имитировать "контроль магнитным полем кристаллической хиральности." Мы докажем, что обнаруженный LD связанс микроскопическим магнитным Давыдовским расщеплением. Этот Л.Д. весьма чувствителен к тонким изменениям в спиновых подсистем, которые позволили нам наблюдать расщепление фазового перехода в несоизмеримы магнитная фаза в двух переходов (T*1= 8,5 и Т*2 = 7,9 К) и предположить эллиптическую спиральную структуру ниже T*1, вместо простой круговой спирали предложенный ранее.

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Держатели документа:
RAS, Inst Spect, Moscow 142190, Russia.
RAS, Ioffe Phys Tech Inst, St Petersburg 194021, Russia.
RAS, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Boldyrev, K. N.; Pisarev, R. V.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич; Popova, M. N.; Russian Academy of Sciences under the Programs for Basic Research; Russian Federation [MK-3521.2015.2]; Russian Foundation for Basic Research [15-32-20613, 15-02-04222]; Ministry of Education and Science of the Russian Federation [14.B25.0031.25]
}
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9.


   
    Large directional optical anisotropy in multiferroic ferroborate / A. M. Kuzmenko [et al.] // Phys. Rev. B. - 2015. - Vol. 92, Is. 18. - Ст. 184409, DOI 10.1103/PhysRevB.92.184409. - Cited References: 44. - This work was supported by the Russian Foundation for Basic Research (14-02-91000, 15-02-07647, 14-02-00307, 13-02-12442, 15-42-04186), Sci. school-924.2014.2, and by the Austrian Science Fund (I815-N16, I1648-N27, W1243) . - ISSN 1098-0121
РУБ Physics, Condensed Matter
Рубрики:
DICHROISM
   BIREFRINGENCE

   RFe3(BO3)4

   POLARIZATION

   EXCITATIONS

   RESONANCE

   Cr2O3

Аннотация: One of the most fascinating and counterintuitive recent effects in multiferroics is directional anisotropy, the asymmetry of light propagation with respect to the direction of propagation. In such case the absorption in a material can be different for opposite directions. Besides absorption, different velocities of light for different directions of propagation may be also expected, which is termed directional birefringence. In this work, we demonstrate large directional anisotropy in multiferroic samarium ferroborate. The effect is observed for linear polarization of light in the range of millimeter wavelengths, and it survives down to low frequencies. The dispersion and absorption close to the electromagnon resonance can be controlled by external magnetic field and are fully suppressed in one direction. By changing the geometry of the external field, samarium ferroborate shows giant optical activity, which makes this material a universal tool for optical control: with a magnetic field as an external parameter it allows switching between two functionalities: polarization rotation and directional anisotropy.

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Держатели документа:
Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, Russian Federation
Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria
L. V. Kirensky Institute of Physics, Siberian Branch of RAS, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Kuzmenko, A. M.; Dziom, V.; Shuvaev, A.; Pimenov, A.; Schiebl, M.; Mukhin, A. A.; Ivanov, V. Y.; Gudim, I. A.; Гудим, Ирина Анатольевна; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич
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10.


    Krinitsyn, A.
    Cluster size and shape effect on the electronic structure of the Hubbard model within the norm-conserving cluster perturbation theory / A. Krinitsyn, S. Nikolaev, S. G. Ovchinnikov // J. Supercond. Nov. Magn. - 2014. - Vol. 27, Is. 4. - P. 955-963, DOI 10.1007/s10948-013-2418-7. - Cited References: 59. - This work was supported by Grants NSh-1044.2012.2 and MK-1168.2012.2, Siberian Federal University: Grant F-11, and the Presidium of RAS Program 20.7. . - ISSN 1557-1939. - ISSN 1557-1947
РУБ Physics, Applied + Physics, Condensed Matter
Рубрики:
NARROW ENERGY-BANDS
   CUPRATE SUPERCONDUCTORS

   PHOTOEMISSION SPECTRA

   PSEUDOGAP

   ANTIFERROMAGNET

   EXCITATIONS

   EVOLUTION

   SYSTEMS

   PHASE

   STATE

Кл.слова (ненормированные):
Cluster perturbation theory -- Hubbard model -- Strong correlations -- Density of states -- Fermi surface
Аннотация: Within a new norm-conserving approach to the cluster perturbation theory (CPT) for the 2d Hubbard model we study the effect of the cluster size and shape on the electronic structure. We have compared two type of clusters, 4-cluster (2x2) and 5-cluster (cruciform of 5 atoms). With 4-cluster we can treat exactly the first and second neighbours correlations, C (1) and C (2). With 5-cluster the third neighbour correlations C (3) are also treated exactly. The band structure in the CPT with 4- and 5-clusters differs remarkably. The quasiparticle spectral weight map for 5-clusters is very similar to the Quantum Monte Carlo (QMC) and the variational CPT data. With increasing doping, small hole Fermi surface transforms into conventional Fermi-liquid type large Fermi surface through Lifshitz quantum phase transitions.

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Держатели документа:
Dostoyevsky Omsk State Univ, Omsk 644077, Russia
Siberian Fed Univ, Krasnoyarsk 660041, Russia
Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Nikolaev, S.; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Siberian Federal University [F-11]; Presidium of RAS Program [20.7]; [NSh-1044.2012.2]; [MK-1168.2012.2]
}
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11.


    Dzebisashvili, D. M.
    Fermi surface evolution in the ensemble of spin-polarized quasiparticles in La2 - xSrxCuO4 / D. M. Dzebisashvili, V. V. Val'kov, A. F. Barabanov // JETP Letters. - 2014. - Vol. 98, Is. 9. - P. 528-533, DOI 10.1134/S0021364013220049. - Cited References: 36. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Mesoscopic and Disordered Structures"), by the Russian Foundation for Basic Research (project nos. 13-02-00909, 13-02-00523, and 11-02-98007-Siberia), and by the Dynasty Foundation. . - ISSN 0021-3640. - ISSN 1090-6487
РУБ Physics, Multidisciplinary
Рубрики:
SADDLE-POINT SINGULARITY
   ANTIFERROMAGNETIC CORRELATIONS

   CUPRATE SUPERCONDUCTORS

   NORMAL-STATE

   MODEL

   BI2SR2CACU2O8+DELTA

   YBA2CU3O6.9

   LA2CUO4

   EXCITATIONS

   YBA2CU4O8

Аннотация: For the spin-fermion model, it has been shown that the concept of spin polarons makes it possible to reproduce fine details of the Fermi surface evolution in the nodal direction of La2-xSrxCuO4 occurring with changes in the doping level x. The physics here is determined by the spin-correlated hopping of charge carriers and by the doping dependence of the inverse magnetic correlation length. © 2013 Pleiades Publishing, Inc.

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Публикация на русском языке Дзебисашвили, Дмитрий Михайлович. Эволюция ферми-поверхности ансамбля спин-поляронных квазичастиц в La2−xSrxCuO4 [Текст] / Д. М. Дзебисашвили, В. В. Вальков, А. Ф. Барабанов // Письма в Журн. эксперим. и теор. физ. : Наука, 2013. - Т. 98 Вып. 9. - С. 596-601

Держатели документа:
Russian Acad Sci, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia
Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
Russian Acad Sci, Inst High Pressure Phys, Troitsk 142092, Moscow Region, Russia

Доп.точки доступа:
Val'kov, V. V.; Вальков, Валерий Владимирович; Barabanov, A. F.; Дзебисашвили, Дмитрий Михайлович
}
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12.


    Val'kov, V. V.
    Effect of the concentration-dependent spin-charge correlations on the evolution of the energy structure of the 2D Emery model / V. V. Val'kov, D. M. Dzebisashvili, A. F. Barabanov // J. Exp. Theor. Phys. - 2014. - Vol. 118, Is. 6. - P. 959-970, DOI 10.1134/S1063776114060223. - Cited References: 48. - This work was supported by the program "Quantum Physics of Mesoscopic and Disordered Systems" of the Presidium of the Russian Academy of Sciences, the Russian Foundation for Basic Research (project nos. 13-02-00909, 13-02-00523, and 13-02-98013_r-sibir), and the Dynasty foundation. . - ISSN 1063-7761. - ISSN 1090-6509
РУБ Physics, Multidisciplinary
Рубрики:
SADDLE-POINT SINGULARITY
   CUPRATE SUPERCONDUCTORS

   FERMI-SURFACE

   ANTIFERROMAGNETIC CORRELATIONS

   NORMAL-STATE

   Bi2Sr2CaCu2O8+δ

   EXCITATIONS

   YBa2Cu3O6.9

   La2CuO4

   YBa2Cu4O8

Аннотация: It is shown using the 2D Emery model that the strong coupling between the spin subsystem of copper ions in the singlet state and the subsystem of oxygen holes considerably reduces the spectral intensity of the correlation function for holes on the Fermi contour. Spin-charge correlations are manifested in the existence of two channels. The first channel is due to the p-d exchange coupling of spins of the oxygen and copper holes. The second channel appears as a result of spin-correlated hoppings, when the motion of holes over oxygen ions is accompanied by spin-flip processes (i.e., simultaneous changes in the spin projections of an oxygen hole and a copper ion). It is established as a result of self-consistent calculations that the allowance for the concentration dependence of spin correlators and multicenter spin-charge correlators appearing in the dispersion equation ensures a decrease in the energy of the system and considerably affects the evolution of the Fermi surface under hole doping.

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Публикация на русском языке Вальков, Валерий Владимирович. Влияние концентрационно-зависимых спин-зарядовых корреляций на эволюцию энергетической структуры двумерной модели Эмери [Текст] / В. В. Вальков, Д. М. Дзебисашвили, А. Ф. Барабанов // Ж. эксперим. и теор. физ. : Наука, 2014. - Т. 145 Вып. 6. - С. 1087-1100

Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
Russian Acad Sci, Inst High Pressure Phys, Moscow 142190, Russia

Доп.точки доступа:
Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Barabanov, A. F.; Барабанов А. Ф.; Вальков, Валерий Владимирович; Presidium of the Russian Academy of Sciences; Russian Foundation for Basic Research [13-02-00909, 13-02-00523, 13-02-98013_r-sibir]; Dynasty foundation
}
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13.


   
    Electronic transitions and genuine crystal-field parameters in copper metaborate CuB2O4 / R. V. Pisarev [et al.] // Phys. Rev. B. - 2011. - Vol. 84, Is. 7. - Ст. 75160, DOI 10.1103/PhysRevB.84.075160. - Cited References: 65. - Useful discussions with W. Weber on crystal-field splitting of 3d states in cuprates are appreciated. We thank H.-J. Weber for the help in using Cary 2300 spectrophotometer. This work is supported by the Russian Foundation for Basic Research (project No. 09-02-00070) and Federal Agency for Science and Innovations (Grant No. 02.740.11.0384). A. M. K. acknowledges the financial support from the Committee for Science and Higher Education of the Government of Saint Petersburg. . - ISSN 1098-0121
РУБ Physics, Condensed Matter
Рубрики:
OPTICAL-ABSORPTION
   PHASE-DIAGRAM

   CUGEO3

   SPECTRUM

   SUPERCONDUCTORS

   EXCITATIONS

   SR2CUO2CL2

   SCATTERING

   LA2CUO4

   CUPRATE

Аннотация: We present and analyze high-resolution alpha-, sigma-, and pi-polarized absorption spectra related to d-d electronic transitions in tetragonal metaborate CuB2O4 where copper Cu2+ ions occupy two crystallographically distinct 4b and 8d positions. The spectra are characterized by exceptionally rich fine structure in the spectral range of 1.4-2.4 eV. Six zero-phonon (ZP) lines originating from the electronic transitions within the Cu2+ ions in both positions are distinguished and identified. Symmetry analysis explains polarization properties of the ZP lines in the 8d positions but only partially explains them in the 4b positions. Reliable assignment of all six ZP lines to specific transitions allowed us to calculate genuine cubic Dq and tetragonal Ds and Dt crystal-field parameters for both positions. We show that the (3r(2) - z(2)) state, the energy of which is the measure of the Jahn-Teller splitting, is the highest 3d state for both types of Cu2+ ion positions. Using the obtained crystal-field parameters as the reference values, we estimated Dq, Ds, and Dt for several other cuprates with different Cu-O bond lengths. In particular, the 3d level splitting in La2CuO4, Nd2CuO4, CuGeO3, Sr2CuO2Cl2, and Cu3B7O13Cl was analyzed. Our estimates suggest that the Jahn-Teller splitting in some of these cuprates is larger than it was assumed previously.

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Держатели документа:
[Pisarev, R. V.
Kalashnikova, A. M.] Russian Acad Sci, AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia
[Schoeps, O.] Dortmund Tech Univ, Inst Phys, D-44221 Dortmund, Germany
[Bezmaternykh, L. N.] Russian Acad Sci, Siberian Branch, Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН
Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russian Federation
Institute of Physics, Dortmund Technical University, 44221 Dortmund, Germany
Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Pisarev, R. V.; Kalashnikova, A. M.; Schops, O.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич
}
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14.


    Ovchinnikov, S. G.
    From underdoped to overdoped cuprates: two quantum phase transitions / S. G. Ovchinnikov, E. I. Shneyder, M. M. Korshunov // J. Phys.: Condens. Matter. - 2011. - Vol. 23, Is. 4. - Ст. 45701, DOI 10.1088/0953-8984/23/4/045701. - Cited References: 58. - We would like to thank S Sakai for useful discussions. The authors acknowledge support by the Russian Foundation for Basic Research (grant N 09-02-00127), by the Integration Program of SBRAS N40, the Presidium RAS Program 5.7, President of Russia (grant MK-1683.2010.2), FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK P891), and in part by the National Science Foundation under grant NSF PHY05-51164. . - ISSN 0953-8984
РУБ Physics, Condensed Matter
Рубрики:
HIGH-TEMPERATURE SUPERCONDUCTORS
   T-J MODEL

   CORRELATED FERMION SYSTEMS

   VALENCE BOND STATE

   MEAN-FIELD-THEORY

   CRITICAL-POINT

   HEISENBERG-ANTIFERROMAGNET

   EXCITATIONS

   PSEUDOGAP

   OSCILLATIONS

Кл.слова (ненормированные):
Critical concentration -- Critical points -- Cuprates -- Density of state -- Fermi surface topology -- Hall effect measurement -- High-T -- Optimal doping -- Overdoped -- Pseudo-gap -- Quantum phase transitions -- Theoretical study -- Copper compounds -- Hall effect -- Magnetic field effects -- Phase diagrams -- Phase transitions
Аннотация: Several experimental and theoretical studies indicate the existence of a critical point separating the underdoped and overdoped regions of the high-T-c cuprates' phase diagram. There are at least two distinct proposals on the critical concentration and its physical origin. The first one is associated with the pseudogap formation for p < p*, with p* approximate to 0.2. The other relies on the Hall effect measurements and suggests that the critical point and the quantum phase transition (QPT) take place at optimal doping, p(opt) approximate to 0.16. Here we have performed a precise density of states calculation and found that there are two QPTs and the corresponding critical concentrations associated with the change of the Fermi surface topology upon doping.

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Держатели документа:
[Ovchinnikov, S. G.
Shneyder, E. I.
Korshunov, M. M.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Shneyder, E. I.] Reshetnev Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
[Korshunov, M. M.] Univ Florida, Dept Phys, Gainesville, FL 32611 USA
ИФ СО РАН
L V Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk 660041, Russian Federation
Reshetnev Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation
Department of Physics, University of Florida, Gainesville, FL 32611, United States

Доп.точки доступа:
Shneyder, E. I.; Шнейдер, Елена Игоревна; Korshunov, M. M.; Коршунов, Максим Михайлович; Овчинников, Сергей Геннадьевич
}
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15.


   
    The Fermi surface and the role of electronic correlations in Sm2-xCexCuO4 / M. M. Korshunov [et al.] // J. Phys.: Condens. Matter. - 2010. - Vol. 22, Is. 1. - Ст. 15701, DOI 10.1088/0953-8984/22/1/015701. - Cited References: 35. - We would like to thank A A Kordyuk and I Eremin for useful discussions. The authors acknowledge support from RFBR (grants 08-02-00021, 10-02-00662, 08-02-91200 and 07-02-00226), the RAS programs on 'Low temperature quantum phenomena', 'Quantum physics of condensed matter' and 'Strongly correlated electrons solids', President of Russia (grants MK-614.2009.2 (IN) and MK-3227.2008.2 (ZP)), Scientific School (grant SS-1929.2008.2), Interdisciplinary UB-SB RAS project, Dynasty Foundation (ZP) and Russian Science Support Foundation (IN). . - ISSN 0953-8984
РУБ Physics, Condensed Matter
Рубрики:
T-C SUPERCONDUCTOR
   IN-GAP STATES

   SPIN CORRELATIONS

   BAND

   LA2-XSRXCUO4

   EXCITATIONS

   TRANSITION

   EVOLUTION

   SM2CUO4

   OXIDES

Кл.слова (ненормированные):
Antiferromagnetics -- Doping evolution -- Electron-doped -- Electronic correlation -- Emery model -- Experimental data -- Generalized tight bindings -- High-T -- Hybrid scheme -- Magnetic orders -- Spin-liquid -- Tight binding model -- Two-regime -- Antiferromagnetism -- Cerium -- Cerium compounds -- Copper oxides -- Corundum -- Doping (additives) -- Fermi surface -- Fermions -- Tin -- Surfaces
Аннотация: Using a LDA + GTB (local density approximation + generalized tight-binding) hybrid scheme we investigate the band structure of the electron-doped high-T-c material Sm2-xCexCuO4. Parameters of the minimal tight-binding model for this system (the so-called three-band Emery model) were obtained within the NMTO (Nth-order muffin-tin orbital) method. The doping evolution of the dispersion and the Fermi surface in the presence of electronic correlations was investigated in two regimes of magnetic order: short-range (spin-liquid) and long-range (antiferromagnetic metal). Each regime is characterized by the specific topologies of the Fermi surfaces and we discuss their relation to recent experimental data.

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Держатели документа:
[Korshunov, M. M.] Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
[Korshunov, M. M.
Zakharova, E. V.
Ovchinnikov, S. G.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Nekrasov, I. A.] Russian Acad Sci, Inst Electrophys, Ekaterinburg 620016, Russia
[Pchelkina, Z. V.] Russian Acad Sci, Inst Met Phys, Ekaterinburg 620219, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
ИФ СО РАН
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany
L v Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk 660036, Russian Federation
Institute for Electrophysics, Russian Academy of Sciences, Ekaterinburg 620016, Russian Federation
Institute for Metal Physics, Russian Academy of Sciences, Ekaterinburg 620219, Russian Federation
Siberian Federal University, Krasnoyarsk 660041, Russian Federation

Доп.точки доступа:
Korshunov, M. M.; Коршунов, Максим Михайлович; Zakharova, E. V.; Nekrasov, I. A.; Pchelkina, Z. V.; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич
}
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16.


    Ovchinnikov, S. G.
    Lifshits Quantum Phase Transitions and Rearrangement of the Fermi Surface upon a Change in the Hole Concentration in High-Temperature Superconductors / 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 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
T-J MODEL
   CORRELATED ELECTRONS

   COPPER OXIDES

   SPECTRUM

   PSEUDOGAP

   METAL

   FLUCTUATIONS

   EXCITATIONS

   INSULATOR

   SYSTEMS

Кл.слова (ненормированные):
Critical points -- Cuprates -- Electron heat -- Electron structures -- Experimental data -- High-T -- Layered cuprates -- Low temperatures -- Normal phase -- Quantum oscillations -- Quantum phase transitions -- Sign reversal -- Strong correlation -- Copper compounds -- Electronic structure -- Equations of state -- Fermi surface -- Fermions -- High temperature superconductors -- Hole concentration -- Superconductivity -- Surface structure -- Phase transitions
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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Публикация на русском языке Овчинников, Сергей Геннадьевич. Квантовые фазовые переходы Лифшица и перестройка ферми-поверхности с изменением концентрации дырок в высокотемпературных сверхпроводниках [Текст] / С. Г. Овчинников, М. М. Коршунов, Е. И. Шнейдер // Журнал экспериментальной и теоретической физики. - 2009. - Т. 136 Вып. 5. - С. 898-909

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]
}
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17.


    Aplesnin, S. S.
    Simulation of magnetic properties of the two-dimensional magnetic with anisotropic antiferromagnetic interactions and cluster ordering by quantum Monte Carlo / S. S. Aplesnin, G. . Petrakovskii, N. I. Miroshnichenko // Phys. Lett. A. - 2008. - Vol. 372, Is. 26. - P. 4722-4725, DOI 10.1016/j.physleta.2008.05.010. - Cited References: 12 . - ISSN 0375-9601
РУБ Physics, Multidisciplinary
Рубрики:
SPIN SYSTEM
   EXCITATIONS

   CU3B2O6

   MODEL

Кл.слова (ненормированные):
anisotropic antiferromagnetic -- cluster ordering -- plateau of magnetization -- modulated structure -- exchange in Cu3B2O6 -- Anisotropic antiferromagnetic -- Cluster ordering -- Exchange in Cu3B2O6 -- Modulated structure -- Plateau of magnetization
Аннотация: Magnetic with anisotropic anti ferromagnetic exchange interactions and special topology of coupling in the square lattice with spins pairs ordering is studied by quantum Monte Carlo method. The antiferromagnetic order is found to be more stable as compared to spin liquid state. Exchange interactions and wave vector of structure modulation for Cu3B2O6 is estimated. Neel temperature versus strength of exchange in spin pair is calculated. Plateau and modulation of magnetic structure in field magnetization dependence is revealed. (C) 2008 Elsevier B.V. All rights reserved.

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Держатели документа:
[Aplesnin, S. S.
Petrakovskii, G.] SB RAS, Inst Phys, Krasnoyarsk 660036, Russia
[Aplesnin, S. S.
Miroshnichenko, N. I.] MF Reshetneva Aircosm Siberian State Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
M.F. Reshetneva Aircosmic Siberian State University, Krasnoyarsk, 660014, Russian Federation
Institute of Physics, SB RAS, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Petrakovskii, G. A.; Петраковский, Герман Антонович; Miroshnichenko, N. I.; Аплеснин, Сергей Степанович
}
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18.


   
    Band-gap unification of partially Si-substituted single-wall carbon nanotubes / P. V. Avramov [et al.] // Phys. Rev. B. - 2006. - Vol. 74, Is. 24. - Ст. 245417, DOI 10.1103/PhysRevB.74.245417. - Cited References: 72 . - ISSN 1098-0121
РУБ Physics, Condensed Matter
Рубрики:
SILICON-CARBIDE NANOTUBES
   DENSITY-FUNCTIONAL THEORY

   TOTAL-ENERGY CALCULATIONS

   WAVE BASIS-SET

   ELECTRONIC-STRUCTURE

   AB-INITIO

   NANORODS

   EXCITATIONS

   TRANSITION

   NANOWIRES

Аннотация: The atomic and electronic structure of a set of pristine single wall SiC nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was studied by the local-density approximation (LDA) plane wave band structure calculations. Consecutive substitution of carbon atoms by Si leads to a gap opening in the energetic spectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of the band gap upon the Si concentration. The same substitution for the semiconductor (10,0) single wall carbon nanotubes (SWCNT) results in a band gap minimum (0.27 eV) at similar to 25% of Si concentration. In the Si concentration region of 12-18 %, both types of nanotubes have less than 0.5 eV direct band gaps at the Gamma-Gamma point. The calculation of the chiral (8,2) SWSi0.15C0.85NT system gives a similar (0.6 eV) direct band gap. The regular distribution of Si atoms in the atomic lattice is by similar to 0.1 eV/atom energetically preferable in comparison with a random distribution. Time dependent density functional theory (DFT) calculations showed that the silicon substitution sufficiently increases (roughly by one order of magnitude) the total probability of optical transitions in the near infrared region, which is caused by the opening of the direct band gap in metallic SWCNTs, the unification of the nature and energy of the band gaps of all SWCNT species, the large values of Si3p parallel to r parallel to Si3s radial integrals and participation of Si3d states in chemical bonding in both valence and conductance bands.

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Держатели документа:
Japan Atom Energy Res Inst, Adv Sci Res Ctr, Takasaki Branch, Takasaki, Gumma 3701292, Japan
RAS, SB, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
RAS, Inst Biochem Phys, Moscow 119991, Russia
AIST, Res Inst Computat Sci, Tsukuba, Ibaraki 3058568, Japan
Kyoto Univ, Dept Energy Sci & Technol, Sakyo Ku, Kyoto 6068501, Japan
ИФ СО РАН
Takasaki-branch, Advanced Science Research Center, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan
L.V. Kirensky Institute of Physics SB RAS, 660036 Krasnoyarsk, Russian Federation
Institute of Biochemical Physics of RAS, 119991 Moscow, Russian Federation
Research Institute for Computational Science, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8568, Japan
Department of Energy Science and Technology, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

Доп.точки доступа:
Avramov, P. V.; Аврамов, Павел Вениаминович; Sorokin, P. B.; Fedorov, A. S.; Федоров, Александр Семенович; Fedorov, D. G.; Maeda, Y.
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19.


    Gekht, R. S.
    A quantum spin liquid in a two-layer triangular antiferromagnet / R. S. Gekht, I. N. Bondarenko // J. Exp. Theor. Phys. - 2005. - Vol. 101, Is. 5. - P. 868-880, DOI 10.1134/1.2149066. - Cited References: 43 . - ISSN 1063-7761
РУБ Physics, Multidisciplinary
Рубрики:
ONE-DIMENSIONAL ANTIFERROMAGNETS
   DIMER GROUND-STATE

   MEAN-FIELD THEORY

   HEISENBERG-ANTIFERROMAGNET

   SYSTEM SRCU2(BO3)(2)

   PHASE-TRANSITION

   GAP

   FLUCTUATIONS

   EXCITATIONS

   LATTICE

Кл.слова (ненормированные):
Antiferromagnetic materials -- Magnetic fields -- Magnetization -- Phase diagrams -- Spectrum analysis -- Thermodynamics -- Analogous systems -- Square lattices -- Thermodynamic quantities -- Two-layer triangular antiferromagnets -- Quantum theory
Аннотация: The possibility of implementing a quantum-spin-liquid-type state in a two-layer triangular spin-1/2 antiferromagnet at T = 0 is investigated. The ratio of intra- to interlayer exchange constants (j) is found under which a transition from the classical state with 120 degrees triangular order to a quantum state with zero magnetization per site occurs; in this case, the spins of adjacent layers form singlets that are separated from triplet excitations by an energy gap. Compared with an analogous system with the square lattice, the range of j in which the classical ordered state is realized turns out to be an order of magnitude smaller due to the effects of frustration; in this case, the behavior of thermodynamic quantities is analogous, on the whole, to that in two-layer square lattices; a difference manifests itself in the behavior of the gap in the spectrum of quasiparticles in an external magnetic field h. For small fields h, a j-h phase diagram is constructed that determines the domains in which the 120 degrees and the singlet phases exist. It is established that, in the neighborhood of the second-order phase transition, the contribution, to the thermodynamic quantities, of longitudinal spin fluctuations, which are disregarded in the spin-wave description, is comparable to the contribution of transverse fluctuations. (c) 2005 Pleiades Publishing, Inc.

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

Доп.точки доступа:
Bondarenko, I. N.
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20.


    Ignatchenko, V. A.
    Waves in a superlattice with arbitrary interlayer boundary thickness / V. A. Ignatchenko, O. N. Laletin // Phys. Solid State. - 2004. - Vol. 46, Is. 12. - P. 2292-2300, DOI 10.1134/1.1841396. - Cited References: 34 . - ISSN 1063-7834
РУБ Physics, Condensed Matter
Рубрики:
PERIODIC STRUCTURES
   RAYLEIGH-WAVES

   LAYERED MEDIUM

   ELASTIC-WAVES

   SPIN-WAVES

   SPECTRUM

   MEDIA

   PROPAGATION

   EXCITATIONS

   MULTILAYERS

Аннотация: The transmittance D(omega), reflectance R(omega), and dispersion omega(k) are investigated for waves of various nature propagating through a one-dimensional superlattice (multilayer structure) with arbitrary thickness of the interlayer boundary. The dependences of the band gap widths Deltaomega(m) and their positions in the wave spectrum of the superlattice on the interlayer boundary thickness d and the band number m are calculated. Calculations are performed in terms of the modified coupled-mode theory (MCMT) using the frequency dependence of R(omega), as well as in the framework of perturbation theory using the function omega(k), which made it possible to estimate the accuracy of the MCMT method; the MCMT method is found to have a high accuracy in calculating the band gap widths and a much lower accuracy in determining the gap positions. It is shown that the m dependence of Deltaomega(m) for electromagnetic (or elastic) waves is different from that for spin waves. Furthermore, the widths of the band gaps with m = 1 and 2 are practically independent of d, whereas the widths of all gaps for m 2 depend strongly on d. Experimental measurements of these dependences allow one to determine the superlattice interface thicknesses by using spectral methods. (C) 2004 MAIK "Nauka/Interperiodica".

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Держатели документа:
Russian Acad Sci, Siberian Div, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Krasnoyarsk State Univ, Krasnoyarsk 660041, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russian Federation
Krasnoyarsk State University, Krasnoyarsk, 660041, Russian Federation

Доп.точки доступа:
Laletin, O. N.; Игнатченко, Вальтер Алексеевич
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