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1.


    Bayukov, O. A.
    Application of the superexchange model to the evaluation method of exchange and 3d-electron transfer parameters in magnetodielectrics / O. A. Bayukov, A. F. Savitskii // Phys. Status Solidi B. - 1989. - Vol. 152, Is. 2. - P. K51-K53, DOI 10.1002/pssb.2221520236. - Cited References: 6 . - ISSN 0370-1972
РУБ Physics, Condensed Matter


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Доп.точки доступа:
Savitskii, A. F.; Баюков, Олег Артемьевич
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2.


   
    Crystal growth, structure, magnetic properties and theoretical exchange interaction calculations of Cu2MnBO5 / S. Sofronova [et al.] // J. Magn. Magn. Mater. - 2016. - Vol. 420. - P. 309-316, DOI 10.1016/j.jmmm.2016.07.019. - Cited References: 35. - X-ray diffraction experiment was carried out at the Centre on Molecular Design and Ecologically Safe Technologies at the Novosibirsk State University. The reported study was funded by Russian Foundation for Basic Research (RFBR) and Government of Krasnoyarsk Territory according to the research project No. 16-42-243028. . - ISSN 0304-8853
РУБ Materials Science, Multidisciplinary + Physics, Condensed Matter
Рубрики:
SPIN-GLASS BEHAVIOR
   SINGLE-CRYSTALS

   SUPEREXCHANGE INTERACTIONS

   LUDWIGITE

   DIELECTRICS

   CO3B2O6NI3B2O6

   WARWICKITES

   FE3O2BO3

   IFEFFIT

   NI3B2O6

Кл.слова (ненормированные):
Oxyborates -- Ludwigites -- XMCD -- EXAFS -- Magnetism
Аннотация: Single crystals of ludwigite Cu2MnBO5 were synthesized by flux growth technique. The detailed structural and magnetic characterizations of the synthesized samples have been carried out. The cations composition of the studied crystal was determined using X-ray diffraction and EXAFS technique, the resulting composition differ from the content of the initial Mn2O3–CuO components of the flux. Magnetic susceptibility measurements and the calculations of the exchange integrals in frameworks of indirect coupling model revealed that monoclinic distortions strongly affect exchange interactions and appearance of magnetic ordering phase at the temperature T=93 K. The hypothesis of the existence of several magnetic subsystems was supposed. © 2016 Elsevier B.V.

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Держатели документа:
L.V. Kirensky Institute of Physics, Siberian Branch of Russian Academy of Science, Krasnoyarsk, Russian Federation
M V Reshetnev Siberian State Aerospace University, Krasnoyarsk, Russian Federation
V.S. Sobolev Institute of Geology and Mineralogy, SB RAS, Novosibirsk, Russian Federation
Novosibirsk State University, Novosibirsk, Russian Federation
Institute of Physics, University of Mainz, Mainz, Germany
Institute of Inorganic and Analytical Chemistry, University of Mainz, Mainz, Germany
Lund University, MAX IV Laboratory, Lund, Sweden
National Research Centre “Kurchatov Institute”, Moscow, Russian Federation

Доп.точки доступа:
Sofronova, S. N.; Софронова, Светлана Николаевна; Moshkina, E. M.; Мошкина, Евгения Михайловна; Nazarenko, I. I.; Назаренко, Илья Иванович; Seryotkin, Yu. V.; Nepijko, S. A.; Ksenofontov, V.; Medjanik, K.; Veligzhanin, A. A.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич
}
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3.


   
    Effect of magnetic frustrations on magnetism of the Fe3BO5 and Co3BO5 ludwigites / Y. V. Knyazev [et al.] // J. Magn. Magn. Mater. - 2019. - Vol. 474. - P. 493-500, DOI 10.1016/j.jmmm.2018.10.126. - Cited References: 33. - The Russian Foundation for Basic Research, Russia (project no. 17-02-00826-a ). S.G.O. thanks the Russian Academy of Science , Russia (project no. 0356-2017-0030 ) for financial support. J.B. and A.A. acknowledge the financial support of the Spanish MINECO-MAT2017-83468R project, Aragonese E-12 17R RASMIA (co-funded by Fondo Social Europeo), and the European Union (FEDER (ES)). . - ISSN 0304-8853
Кл.слова (ненормированные):
Antiferromagnetics -- Superexchange interactions -- Frustrations
Аннотация: The magnetic structures of Fe3BO5 and Co3BO5 ludwigites have been studied experimentally by magnetic measurements and theoretically by the combination of the group theoretical analysis and semi empiric calculations of the superexchange interactions. The different collinear spin configurations in the triads 3-1-3 and 4-2-4 including ferromagnetic, antiferromagnetic and dimer have been considered. For Fe3BO5 the antiferromagnetic state with zero magnetic moment per unit cell, showing the lowest energy, results to be the most probable magnetic ground state. The unusual magnetic structure comprising two virtually independent orthogonal subsystems is formed to avoid heavy frustrations of superexchange interactions between the 3-1-3 and 4-2-4 spin ladders. In Co3BO5 the magnetic frustrations present for the Co3+ high-spin state are quenched for a Co3+ low spin state resulting in the ferrimagnetic long-range order. The obtained results are discussed in comparison with experimental magnetic data.

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Держатели документа:
Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, 660036, Russian Federation
Siberian State University of Science and Technologies, Krasnoyarsk, 660014, Russian Federation
Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza and Departamento de Fisica de la Materia Condensada, Zaragoza, 50009, Spain
Servicio de Medidas Fisicas, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain

Доп.точки доступа:
Knyazev, Yu. V.; Князев, Юрий Владимирович; Kazak, N. V.; Казак, Наталья Валерьевна; Nazarenko, I. I.; Назаренко, Илья Иванович; Sofronova, S. N.; Софронова, Светлана Николаевна; Rostovtsev, N. D.; Bartolome, J.; Arauzo, A.; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич
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4.


   
    Ferromagnetism in single-valent manganites / I. O. Troyanchuk [et al.] // J. Alloys Compd. - 2015. - Vol. 619. - P. 719-725, DOI 10.1016/j.jallcom.2014.08.236. - Cited References: 46. - The authors would like to thank J.B. Goodenough for the fruitful discussion. This work has been supported by Belarusian Republican Foundation for Fundamental Research (Grant F14R-040). . - ISSN 0925-8388. - ISSN 1873-4669
РУБ Chemistry, Physical + Materials Science, Multidisciplinary + Metallurgy & Metallurgical Engineering
Рубрики:
PHASE-SEPARATION
   DOPED MANGANITES

   DOUBLE EXCHANGE

   DIFFRACTION

   OXIDES

   NMR

Кл.слова (ненормированные):
Magnetically ordered materials -- Solid state reactions -- Exchange and superexchange -- Magnetic measurements -- Neutron diffraction
Аннотация: Structural and magnetization measurements have been performed on the La0.7Sr0.3Mn0.85 Nb 0.15 - x 5 + Mg x 2 + O3 stoichiometric compounds. With rise of the Mg2+ content the formal oxidation state manganese increases from +3 ( x = 0 ) up to +3.55 ( x = 0.15 ) . The compositions with 0 ⩽ x ≤ 0.08 undergo a structural transition from rhombohedral to orthorhombic symmetry below room temperature whereas x = 0.1 and x = 0.15 compounds are rhombohedral down to 2 K. The structural parameters evidence that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The Mg-free compound is ferromagnetic with the Curie point of around 150 K and a magnetic moment of 3.1 μ B /Mn. The substitution of Nb5+ with Mg2+ leads to a gradual weakening of the ferromagnetic component while in the x = 0.15 compound A-type antiferromagnetic short-range order is stabilized in spite of macroscopic R 3 ¯ c symmetry. All the compositions show insulating behavior. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder induced by Nb5+ and Mg2+ ions leads to suppression of ferromagnetism.

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Держатели документа:
Sci Pract Mat Res Ctr NAS Belarus, Minsk 220072, Byelarus
Helmholtz Zentrum Berlin, D-14109 Berlin, Germany
Joint Inst Nucl Res, Dubna 141980, Russia
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France
ISMRA Univ Caen, UMR Associee CNRS 6508, Lab CRISMAT, F-14050 Caen, France
Univ Caen, F-14050 Caen, France

Доп.точки доступа:
Troyanchuk, I. O.; Bushinsky, M. V.; Sikolenko, V.; Efimov, V.; Volkov, N. V.; Волков, Никита Валентинович; Tobbens, D. M.; Ritter, C.; Raveau, B.
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5.


    Gavrichkov, V. A.
    Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure / V. A. Gavrichkov, S. I. Polukeev, S. G. Ovchinnikov. - Electronic text data // ArXiv. - 2019. - Ст. 1911.06482. - Cited References: 63. - We acknowledge the support of the Russian Science Foundation through Grant 18-12-00022.
Рубрики:
Materials Science
   Strongly Correlated Electrons

Аннотация: We derived simple rules for the sign of 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 individual 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 superexchange interaction of a number of oxides with magnetic cations in electron configurations from d2 till 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 superexchange interaction.

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Держатели документа:
Kirensky Institute of Physics, Akademgorodok 50, bld.38, Krasnoyarsk, 660036 Russia

Доп.точки доступа:
Polukeev, S. I.; Полукеев, Семен Игоревич; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Гавричков, Владимир Александрович
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6.


    Gavrichkov, V. A.
    Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure / 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 2469-9969
РУБ Materials Science, Multidisciplinary + Physics, Applied + Physics, Condensed Matter
Рубрики:
EXCHANGE INTERACTION
   PHASE-TRANSITIONS

   STATE

   ELECTRON

   IRON

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]
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7.


    Gavrichkov, V. A.
    Contribution from optically excited many-electron states to the superexchange interaction in Mott-Hubbard insulators / V. A. Gavrichkov, S. I. Polukeev, S. G. Ovchinnikov // Phys. Rev. B. - 2017. - Vol. 95, Is. 14. - Ст. 144424, DOI 10.1103/PhysRevB.95.144424. - Cited References: 49. - This work was supported by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory and Krasnoyarsk Region Science and Technology Support Fund to the research Project No. 17-42-240212. We are also grateful to the RFBR Grants No. 16-02-00273, No. 16-02-00098, and No. NSh-7559.2016.2. . - ISSN 1098-0121
Аннотация: We investigated the effects of excited many-electron states in the optical control of the magnetic state in undoped Mott-Hubbard insulator. To derive the spin Hamiltonian in material under optical pumping one has used a many-electron approach based on the X-operator representation. Extending the projection operators approach on arbitrary energy spectra of the Mott-Hubbard insulator, we obtained the Hamiltonian of superexchange interaction in analytical form. The Hamiltonian includes the spin-exciton variables which are usually missing in discussion on the magnetic response to optical pumping. The superexchange is also not additive over contributions from the ground and optical excited states, and nonzero contributions to the Dzyaloshinskii-Moriya interaction are induced in insulators with different spins at the ground and excited cell states. As a test, a microscopic background for the optical induced superexchange was analyzed in La2CuO4 (further La214) and FeBO3 with spins 1/2 and 5/2, respectively. © 2017 American Physical Society.

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Держатели документа:
Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, Russian Federation
National Research Nuclear University MEPHI, Moscow Engineering Physics Institute, Moscow, Russian Federation

Доп.точки доступа:
Polukeev, S. I.; Полукеев, Семен Игоревич; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич; Гавричков, Владимир Александрович
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8.


    Gavrichkov, V. A.
    Magnetic interaction in doped 2D perovskite cuprates with nanoscale inhomogeneity: Lattice nonlocal effects vs. superexchange / V. A. Gavrichkov, S. I. Polukeev // Condens. Matter. - 2022. - Vol. 7, Is. 4. - Ст. 57, DOI 10.3390/condmat7040057. - Cited References: 78. - This work was supported by the Russian Science Foundation, research grant RSF No.22-22-00298 . - ISSN 2410-3896
   Перевод заглавия: Магнитное взаимодействие в допированных 2d перовскитах с наноразмерной неоднородностью: решеточные нелокальные эффекты против суперобмена
Кл.слова (ненормированные):
superexchange interaction -- nanoscale inhomogeneity -- doped 2D perovskite cuprates
Аннотация: We have studied the superexchange interaction Jij in doped 2D cuprates. The AFM interaction strongly depends on the state of the lattice of a CuO2 layer surrounded by two LaO rock salt layers. In a static U and D stripe nanostructure, the homogeneous AFM interaction is impossible due to the U/D/U… periodic stripe sequence and TN=0. In a dynamic stripe nanostructure, the ideal CuO2 layer with nonlocal effects and the homogeneous AFM interaction are restored. However, the interaction Jij decreases by the exponential factor due to partial dynamic quenching. The meaning of the transition from the dynamic to the static cases lies in the spontaneous θ-symmetry breaking with respect to the rotation of all the tilted CuO6 octahedra by an orientation angle δθ=n⋅(45°) (where n=1÷4) in the U and D stripe nanostructure of the CuO2 layer. Moreover, the structural features help to study various experimental data on the charge inhomogeneity, Fermi level pinning in the p type cuprates only and time reversal symmetry breaking from a unified point of view.

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Держатели документа:
Kirensky Institute of Physics, Akademgorodok 50, building 38, 660036 Krasnoyarsk, Russia

Доп.точки доступа:
Polukeev, S. I.; Полукеев, Семен Игоревич; Гавричков, Владимир Александрович
}
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9.


    Gavrichkov, V. A.
    Magnetic interaction in doped 2D perovskites with nanoscale inhomogenety: lattice nonlocal effects vs superexchange / V. A. Gavrichkov, S. I. Polukeev // XIX Конференция "Сильно коррелированные электронные системы и квантовые критические явления" : сборник тезисов / чл. прогр. ком. С. Г. Овчинников и др. - Москва, 2022. - P. 194-196. - Библиогр.: 1 . - ISBN 978-5-4344-0954-4

,
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Доп.точки доступа:
Овчинников, Сергей Геннадьевич \чл. прогр. ком.\; Ovchinnikov, S. G.; Polukeev, S. I.; Гавричков, Владимир Александрович; "Сильно коррелированные электронные системы и квантовые критические явления", конференция(19 ; 2022 ; 26 мая ; Москва); Российская академия наук; Физический институт им. П.Н. Лебедева РАН
}
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10.


    Gavrichkov, V. A.
    Superexchange in 2D perovskite HTSC with stripe nanostructure / V. A. Gavrichkov // International conference "Functional materials" : book of abstracts / ed. V. N. Berzhansky ; org. com. S. G. Ovchinnikov [et al.]. - Simferopol, 2021. - P. 223-2224. - Библиогр.: 3 назв. - The reported study was supported by the grant RFFI 19-02-00034 and the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, and Krasnoyarsk Regional Fund of Science according to the research project ”Studies of superexchange and electron-phonon interactions in correlated systems as a basis for searching for promising functional materials No. 20-42-240016.

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Доп.точки доступа:
Berzhansky, V. N. \ed.\; Бержанский, Владимир Наумович; Ovchinnikov, S. G. \org. com.\; Овчинников, Сергей Геннадьевич; Гавричков, Владимир Александрович; "Functional materials", International conference(2021 ; Oct. 4-8 ; Alushta, Russia); Крымский федеральный университет имени В.И. Вернадского
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