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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bayukov O. A., Savitskii A. F.
Заглавие : Application of the superexchange model to the evaluation method of exchange and 3d-electron transfer parameters in magnetodielectrics
Место публикации : Phys. Status Solidi B. - 1989. - Vol. 152, Is. 2. - P.K51-K53. - ISSN 0370-1972, DOI 10.1002/pssb.2221520236
Примечания : Cited References: 6
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure [Electronic resource]
Место публикации : ArXiv. - 2019. - Ст.1911.06482
Вид и объем ресурса: Electronic text data
Примечания : Cited References: 63. - We acknowledge the support of the Russian Science Foundation through Grant 18-12-00022.
Предметные 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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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 9. - Ст.094409. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.094409. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 65. - We acknowledge the support of the Russian Science Foundation through Grant No. 18-12-00022
Предметные 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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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Contribution from optically excited many-electron states to the superexchange interaction in Mott-Hubbard insulators
Место публикации : Phys. Rev. B: American Physical Society, 2017. - Vol. 95, Is. 14. - Ст.144424. - ISSN 10980121 (ISSN), DOI 10.1103/PhysRevB.95.144424
Примечания : 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.
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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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Moshkina E. M., Nazarenko I. I., Seryotkin Yu. V., Nepijko S. A., Ksenofontov V., Medjanik K., Veligzhanin A. A., Bezmaternykh L. N.
Заглавие : Crystal growth, structure, magnetic properties and theoretical exchange interaction calculations of Cu2MnBO5
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 420. - P.309-316. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.07.019
Примечания : 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.
Предметные рубрики: SPIN-GLASS BEHAVIOR
SINGLE-CRYSTALS
SUPEREXCHANGE INTERACTIONS
LUDWIGITE
DIELECTRICS
CO3B2O6NI3B2O6
WARWICKITES
FE3O2BO3
IFEFFIT
NI3B2O6
Ключевые слова (''Своб.индексиров.''): 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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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Polukeev S. I., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Dependence of superexchange interaction in CrO2 on pressure
Коллективы : Российская академия наук, Уральское отделение РАН, Институт физики металлов им. М. Н. Михеева Уральского отделения РАН, Уральский федеральный университет им. первого Президента России Б.Н. Ельцина, Российский фонд фундаментальных исследований, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : Euro-asian symposium "Trends in magnetism" (EASTMAG-2019): Book of abstracts/ чл. конс. ком.: S. G. Ovchinnikov, N. V. Volkov [et al.] ; чл. прогр. ком. D. M. Dzebisashvili [et al.]. - 2019. - Vol. 2. - Ст.H.P19. - P.103. - ISBN 978-5-9500855-7-4 (Шифр В33/E12-125657784)
Примечания : Cited References: 3. - Support by RSF grant 18-12-00022 is acknowledged
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7.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Polukeev S. I., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Dependence of superexchange interaction in CrO2 on pressure
Коллективы : Институт физики металлов им. М. Н. Михеева Уральского отделения РАН, Институт электрофизики УрО РАН, Международная зимняя школа физиков-теоретиков "Коуровка", "Коуровка", международная зимняя школа физиков-теоретиков
Место публикации : Международная зимняя школа физиков-теоретиков "Коуровка-XXXVIII": тезисы докладов : Верхняя Сысерть, 23 - 29 февр. 2020 г. - Екатеринбург, 2020. - P.70. - ISBN 978-5-9500855-9-8
Примечания : Cited References: 3. - Support by RSF grant № 18-12-00022 is acknowledged
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Kazak N. V., Nazarenko I. I., Sofronova S. N., Rostovtsev N. D., Bartolome J., Arauzo A., Ovchinnikov S. G.
Заглавие : Effect of magnetic frustrations on magnetism of the Fe3BO5 and Co3BO5 ludwigites
Место публикации : J. Magn. Magn. Mater. - 2019. - Vol. 474. - P.493-500. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2018.10.126
Примечания : 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)).
Ключевые слова (''Своб.индексиров.''): 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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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : Effect of pressure on antiferromagnetic and superconducting ordering in systems with heavy fermions
Коллективы : International Interdisciplinary Symposium “Ordering in Minerals and Alloys” (14th; 8 -13 Sept. 2011; Rostov-on-Don)
Место публикации : Bull. Russ. Acad. Sci.: Phys.: Allerton Press, 2012. - Vol. 76, Is. 7. - P.733-736. - ISSN 0022-2860, DOI 10.3103/S1062873812070362
Примечания : Cited References: 7. - This work was supported by the Department of Physical Sciences, Russian Academy of Sciences (the Strong Electron Correlations Program); the Russian Foundation for Basic Research, projects nos. 100200251 and 110200741; the RFBR Sibir’, project no. 110298007; and by the federal target program Scientific and Pedagogical Personnel of an Innovative Russia, 2009–2013.
Ключевые слова (''Своб.индексиров.''): antiferromagnetic orderings--antiferromagnetic orders--antiferromagnetic phasis--antiferromagnetics--cooper instability--effect of pressure--external pressures--heavy fermion--impurity level--localized state--periodic anderson model--seed energy--spin moments--superconducting ordering--superexchange interaction--superconductivity--antiferromagnetism
Аннотация: Characteristics of the superconducting and antiferromagnetic phases of heavy-fermion intermet-allides are described within a periodic Anderson model with allowance for the superexchange interaction between spin moments of the localized states. It is shown that an external pressure that changes the seed energy of an impurity level can rapidly destroy the long-range antiferromagnetic order. The development of the Cooper instability near such an order-disorder transition induces the experimentally observed state in which superconductivity coexists with the antiferromagnetic ordering. В© 2012 Allerton Press, Inc.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Polukeev S. I., Gavrichkov V. A., Ovchinnikov S. G.
Заглавие : Effects of optical intra-gap transitions on superexchange interaction in La2CuO4 with nonequilibrium photoexcited centers
Место публикации : J. Sib. Fed. Univ. Math. Phys. - 2018. - Vol. 11, Is. 2. - P.159-170. - ISSN 19971397 (ISSN), DOI 10.17516/1997-1397-2018-11-2-159-170; Журн. СФУ. Сер. "Математика и физика"
Примечания : Cited References: 39
Ключевые слова (''Своб.индексиров.''): superexchange--optically excited states--mott-hubbard insulator--суперобмен--оптически возбужденные состояния--диэлектрик мотта-хаббарда
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 we have used 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, and is not additive over contributions from the ground and optically excited states. As a test, a microscopic background for the optical induced superexchange was analyzed in La2CuO4 (further La214).Мы исcледовали эффекты возбужденных многоэлектронных состояний в оптическом способе управления магнитным состоянием недопированных Мотт-Хаббардовских материалов. Для вывода спинового гамильтониана в веществе под воздействием оптической накачки был использован многоэлектронный метод, основанный на представлении X-операторов. С помощью обобщенного на произвольный энергетический спектр метода проекционных операторов мы получили гамильтониан суперобменного взаимодействия в аналитической форме. Гамильтониан является не аддитивными по вкладам от основных и оптически возбуждённых состояний, а также содержит спин-экситонные переменные, которые обычно отсутствуют в обсуждении магнитного отклика на оптическую накачку. В качестве конкретного приложения для теории мы рассчитали индуцированный суперобмен для оптически возбужденного купрата La2CuO4 (в дальнейшем La214).
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