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    Эффективные взаимодействия в периодической модели Андерсона в режиме смешанной валентности при сильных корреляциях / В. В. Вальков, Д. М. Дзебисашвили // Теоретическая и математическая физика. - 2008. - Т. 157, № 2. - С. 235-249, DOI 10.4213/tmf6277 . - ISSN 0564-6162. - ISSN 2305-3135
   Перевод заглавия: Effective interactions in the periodic Anderson model in the regime of mixed valency with strong correlations
Кл.слова (ненормированные):
периодическая модель Андерсона -- смешанная валентность -- тяжелые фермионы -- эффективный гамильтониан -- сверхпроводимость
Аннотация: Для периодической модели Андерсона в режиме сильных корреляций с точностью до членов четвертого порядка по параметру V/U (V – интенсивность гибридизационного взаимодействия, U – величина внутриатомного кулоновского отталкивания) построен эффективный гамильтониан H_{\mathrm{eff}}, содержащий взаимодействия, индуцирующие как магнитное упорядочение, так и куперовскую неустойчивость в условиях смешанной валентности редкоземельных ионов. На основе численных расчетов получены данные о зависимости параметров эффективных взаимодействий от расстояния между узлами кристаллической решетки. Показано, что реализация обменных связей соответствует сильно фрустрированной системе локализованных спиновых моментов и способствует подавлению антиферромагнитного параметра порядка с возможным переходом в состояние квантовой спиновой жидкости. Существенно, что среди слагаемых H_{\mathrm{eff}}, индуцирующих переход в сверхпроводящую фазу, содержатся слагаемые, приводящие к d-типу симметрии сверхпроводящего параметра порядка, который реализуется во многих тяжелофермионных соединениях.

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Держатели документа:
Институт физики им. Л. В. Киренского СО РАН

Доп.точки доступа:
Вальков, Валерий Владимирович; Дзебисашвили, Дмитрий Михайлович
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    Комогорцев, Сергей Викторович.
    Новые особенности полевого поведения магнитных корреляций в ферромагнетиках со случайной магнитной анизотропией / С. В. Комогорцев, В. А. Фельк, Р. С. Исхаков // Новое в магнетизме и магнитных материалах : сборник трудов XXIV международной конференции / прогр. ком.: Р. С. Исхаков, С. Г. Овчинников [и др.]. - 2021. - Секция 3: Микромагнетизм и доменная структура. - Ст. 3-62-65. - Библиогр.: 8. - Исследование выполнено при финансовой поддержке РФФИ, Правительства Красноярского края и Красноярского краевого фонда науки в рамках научного проекта № 20-42-240001.
   Перевод заглавия: New features in a field behavior of magnetic correlations in ferromagnets with random magnetic anisotropy
Аннотация: Модели тонкой поликристаллической пленки – тонком слое, состоящем из обменно-связанных кубических блоков со случайной ориентацией осей легкого намагничивания установлено, что скорость смены степенных режимов в полевых зависимостях параметров корреляций намагниченности подтверждает новые эмпирические выражения, предложенные в последних работах. Зависимость дисперсии намагниченности от поля в области существования ряби показывает показатель степени несколько ниже теоретически предсказанного показателя ¾.
The model of a thin polycrystalline film - a thin layer consisting of exchange-coupled cubic blocks with a random orientation of the easy magnetization axes is used to examine of powerlaw regimes in the field behavior magnetic correlation parameters. It was found that the rate of changing of power-law regimes follows new empirical expressions proposed in recent works. The field dependence of the dispersion of magnetization in the region of existence of ripples shows an exponent somewhat lower than the theoretically predicted exponent ¾.

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Держатели документа:
Институт физики им. Л.В. Киренского СО РАН

Доп.точки доступа:
Исхаков, Рауф Садыкович \прогр. ком.\; Iskhakov, R. S.; Овчинников, Сергей Геннадьевич \прогр. ком.\; Ovchinnikov, S. G.; Фельк, Владимир Александрович; Felk V.A.; Исхаков, Рауф Садыкович; Komogortsev, S. V.; "Новое в магнетизме и магнитных материалах", международная конференция(24 ; 2021 ; 1-8 июля ; Москва); Научный совет по физике конденсированных сред РАН; МИРЭА - Российский технологический университет; Московский государственный университет им. М.В. Ломоносова; Магнитное общество России
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Зобов, Владимир Евгеньевич.
Квантовые и классические корреляции в высокотемпературной динамике двух связанных больших спинов / В. Е. Зобов // Теор. и мат. физика. - 2013. - Т. 177, № 1. - С. 111–125DOI 1010.4231/tmf8510
Аннотация: Исследуются динамические корреляции двух связанных спинов в зависимости от времени и величин спиновых квантовых чисел. В высокотемпературном приближении получены аналитические выражения для взаимной информации, квантовой и классической частей корреляций. Наряду с ортогональными измерениями рассмотрены неортогональные измерения с базисом из спиновых когерентных состояний. Показано, что на малых временах при увеличении спиновых квантовых чисел квантовая часть корреляций становится много меньше классической части, тогда как на временах, равных половине квантового периода, это не так.

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Переводная версия Quantum and classical correlations in high-temperature dynamics of two coupled large spins. - [Б. м. : б. и.]

Держатели документа:
Институт физики им. Л.В. Киренского СО РАН

Доп.точки доступа:
Zobov, V. E.
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    Вальков, Валерий Владимирович.
    Майорановские моды в квантовых проволоках конечной длины с электронными корреляциями / В. В. Вальков, В. А. Мицкан, М. С. Шустин // Урал. междунар. зимняя шк. по физике полупроводников : 19 – 24 февраля 2018 г. : гопрограмма и тезисы докладов / чл. прогр. ком. В. В. Вальков. - 2018. - Секция 6 : Электронные свойства низкоразмерных систем. - Ст. L-53. - С. 168
   Перевод заглавия: Majorana zero modes in finite quantum wires with electronic correlations

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Держатели документа:
Институт физики им. Л.В. Киренского СО РАН

Доп.точки доступа:
Вальков, Валерий Владимирович \чл. прогр. ком.\; Val'kov, V. V.; Мицкан, Виталий Александрович; Mitskan, V. A.; Шустин, Максим Сергеевич; Shustin, M. S.; Институт физики металлов Уральского отделения РАН; Уральская международная зимняя школа по физике полупроводников(22 ; 2018 ; февр. ; Екатеринбург)
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Zobov, V. E.
Second moment of multiple-quantum NMR and a time-dependent growth of the number of multispin correlations in solids / V. E. Zobov, A. A. Lundin // J. Exp. Theor. Phys. - 2006. - Vol. 103, Is. 6. - P. 904-916, DOI 10.1134/S1063776106120089. - Cited References: 39 . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
NUCLEAR-MAGNETIC-RESONANCE
   LINE-SHAPE
   SPIN SYSTEMS
   DYNAMICS
   SPECTRA
   COHERENCES
   STATE
   BEHAVIOR
   CRYSTAL
   MODEL
Кл.слова (ненормированные):
Correlation methods -- Mathematical models -- Nuclear magnetic resonance spectroscopy -- Spectrum analysis -- Time series analysis -- Four-spin time correlation -- Multispin correlations -- Second moment -- Time power series -- Quantum theory
Аннотация: The time evolution of multispin correlations (the growth of the number of correlated spins as a function of time) can be observed directly using the multiple-quantum nuclear magnetic resonance spectroscopy of solids. A quantity related to this number, namely, the second moment of the intensity distribution of coherences of different orders in the multiple-quantum spectrum can be calculated using the theory proposed in this work. An approach to the calculation of the four-spin time correlation function through which this moment is expressed is developed. The main sequences of contributions in the expansion of this function into a time power series are summed using the approximation of a large number of neighbors both for systems with a secular dipole-dipole interaction and for systems with a nonsecular effective interaction. An exponential dependence of is obtained. The value of is additionally calculated using an expansion in terms of orthogonal operators for three model examples corresponding to different limiting realizations of spin systems. It is shown that the results of the microscopic theory at least qualitatively agree with both the results obtained for model examples and experimental results obtained recently for adamantane.

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Держатели документа:
Russian Acad Sci, Siberian Div, Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Russian Acad Sci, Semenov Inst Chem Phys, Moscow 117977, Russia
ИФ СО РАН
Kirenskii Institute of Physics, Siberian Division, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation
Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 117977, Russian Federation

Доп.точки доступа:
Lundin, A. A.; Зобов, Владимир Евгеньевич
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Zobov, V. E.
Quantum and classical correlations in the solid-state NMR free induction decay / V. E. Zobov, A. A. Lundin // International Conference Magnetic Resonance: Fundamental Research and Pioneering Applications : Book of abstracts. - 2014. - Ст. P 77. - P. 160. - Cited References: 16
Аннотация: The free induction decay (FID) of the transverse magnetization in a dipolar-coupled rigid lattice is a fundamental problem in magnetic resonance and in the theory of many-body systems. As it was shown earlier the FID shapes for the systems of classical magnetic moments and for quantum nuclear spin ones coincide if there are many nearly equivalent nearest neighbors n in a solid lattice. In this paper, we reduce a multispin density matrix of above system to a two-spin matrix. Then we obtain analytic expressions for the mutual information and the quantum and classical parts of correlations at the arbitrary spin quantum number S, in the high-temperature approximation. The time dependence of these functions is expressed via the derivative of the FID shape. To extract classical correlations for S 1/2 we provide generalized POVM measurement (positive-operator-valued measure) using the basis of spin coherent states. We show that in every pair of spins the portion of quantum correlations changes from 1/2 to 1/(S + 1) when S is growing up, and quantum properties disappear completely only if S → ∞.

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Lundin, A. A.; Зобов, Владимир Евгеньевич
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Zobov, V. E.
Quantum and classical correlations in the solid-state NMR free induction decay / V. E. Zobov, A. A. Lundin // Appl. Magn. Reson. - 2014. - Vol. 45, Is. 11. - P. 1169-1177, DOI 10.1007/s00723-014-0562-2. - Cited References: 16 . - ISSN 0937-9347. - ISSN 1613-7507

РУБ Physics, Atomic, Molecular & Chemical + Spectroscopy
Рубрики:
LATTICE
SPINS
Аннотация: The free induction decay (FID) of the transverse magnetization in a dipolar-coupled rigid lattice is a fundamental problem in magnetic resonance and in the theory of many-body systems. As it was shown earlier the FID shapes for the systems of classical magnetic moments and for quantum nuclear spin ones coincide if there are many nearly equivalent nearest neighbors n in a solid lattice. In this paper, we reduce a multispin density matrix of above system to a two-spin matrix. Then we obtain analytic expressions for the mutual information and the quantum and classical parts of correlations at the arbitrary spin quantum number S, in the high-temperature approximation. The time dependence of these functions is expressed via the derivative of the FID shape. To extract classical correlations for S 1/2 we provide generalized POVM measurement (positive-operator-valued measure) using the basis of spin coherent states. We show that in every pair of spins the portion of quantum correlations changes from 1/2 to 1/(S + 1) when S is growing up, and quantum properties disappear completely only if S → ∞.

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Держатели документа:
RAS, Siberian Branch, LV Kirensky Inst Phys, Krasnoyarsk 660036, Russia
RAS, NN Semenov Inst Chem Phys, Moscow 117977, Russia

Доп.точки доступа:
Lundin, A. A.; Зобов, Владимир Евгеньевич
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Zobov, V. E.
Quantum and classical correlations in high-temperature dynamics of two coupled large spins / V. E. Zobov // THEOR. MATH. PHYS. - 2013. - Vol. 177, Is. 1. - P. 1377-1389, DOI 10.1007/s11232-013-0110-5 . - ISSN 0040-5779
Кл.слова (ненормированные):
generalized measurement -- high-temperature approximation -- mutual information -- quantum correlation -- spin coherent state -- spin dynamics
Аннотация: We study the dynamical correlations between two coupled spins depending on time and the value of the spin quantum numbers. In the high-temperature approximation, we obtain analytic expressions for the mutual information and the quantum and classical parts of correlations. We consider both orthogonal and nonorthogonal measurements in the basis of spin coherent states. We show that at small times, the quantum part of correlations becomes much less than the classical part as the spin quantum numbers increase, while the situation is quite different at times equal to half the quantum period.

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Публикация на русском языке Квантовые и классические корреляции в высокотемпературной динамике двух связанных больших спинов. - [S. l. : s. n.]

Доп.точки доступа:
Зобов, Владимир Евгеньевич
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    Zobov, V. E.
    Quantum and classical correlations in high temperature dynamics of two coupled large spins : conference paper / V. E. Zobov // Proc. SPIE. - 2012. - Vol.8700. - Ст. 87001D. - P. , DOI 10.1117/12.2016982. - Cited References: 17 . - ISSN 0277-786X. - ISSN 978-08194
   Перевод заглавия: Квантовые и классические корреляции в высокотемпературной динамике двух связанных больших спинов
Кл.слова (ненормированные):
Dynamical correlations -- Measurement -- Mutual information -- Nuclear magnetic resonance -- Spin coherent states
Аннотация: We study dynamical correlations of two coupled large spins depending on the time and on the spin quantum numbers. In the high-temperature approximation, we obtain analytical expressions for the mutual informations, quantum and classical parts of correlations. The latter was obtained performing the non-orthogonal projective (POVM) measurements onto the spin coherent states of two spins or one spin, as well as by means of the orthogonal projective measurement of von Neumann. Contribution from quantum correlations is much less than that from classical ones and decreasing with the increase in spin quantum numbers at short times. However, it is not so in a time equal to half of the quantum period. © 2012 SPIE.

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Доп.точки доступа:
Зобов, Владимир Евгеньевич; International Conference on Micro- and Nano-Electronics (Oct. 1-5, 2012 ; Zvenigorod, Russia)
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10.

Zobov, V. E.
Quantum and classical correlations in high temperature dynamics of two coupled large spins / V. E. Zobov // International Conference "Micro- and Nanoelectronics – 2012" : Book of abstracts. - 2012. - Ст. q1-02. - P.

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Доп.точки доступа:
Зобов, Владимир Евгеньевич; "Micro- and nanoelectronics – 2012", Int. Conf. (2012 ; окт. ; 1-5 ; Москва / Звенигород, Россия)
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11.

Zobov, V. E.
Quantum and classical correlations in electron-nuclear spin echo / V. E. Zobov // J. Exp. Theor. Phys. - 2014. - Vol. 119, Is. 5. - P. 817-827, DOI 10.1134/S1063776114110132. - Cited References: 38 . - ISSN 1063-7761. - ISSN 1090-6509

РУБ Physics, Multidisciplinary
Рубрики:
DISCORD
QUBITS
Аннотация: The quantum properties of dynamic correlations in a system of an electron spin surrounded by nuclear spins under the conditions of free induction decay and electron spin echo have been studied. Analytical results for the time evolution of mutual information, classical part of correlations, and quantum part characterized by quantum discord have been obtained within the central-spin model in the high-temperature approximation. The same formulas describe discord in both free induction decay and spin echo although the time and magnetic field dependences are different because of difference in the parameters entering into the formulas. Changes in discord in the presence of the nuclear polarization β I in addition to the electron polarization β S have been calculated. It has been shown that the method of reduction of the density matrix to a two-spin electron-nuclear system provides a qualitatively correct description of pair correlations playing the main role at β S ≈ β I and small times. At large times, such correlations decay and multispin correlations ensuring nonzero mutual information and zero quantum discord become dominant.

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Публикация на русском языке Зобов, Владимир Евгеньевич. Квантовые и классические корреляции в электронно-ядерном спиновом эхе [Текст] / В. Е. Зобов // Журн. эксперим. и теор. физ. : Наука, 2014. - Т. 146 Вып. 5. - С. 933-945

Доп.точки доступа:
Зобов, Владимир Евгеньевич
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12.

Zlotnikov, A. O.
Spin-orbit coupling-induced effective interactions in superconducting nanowires in the strong correlation regime / A. O. Zlotnikov, S. V. Aksenov, M. S. Shustin // Phys. Solid State. - 2020. - Vol. 62, Is. 9. - P. 1612-1618, DOI 10.1134/S1063783420090371. - Cited References: 24. - This study was supported by the Russian Foundation for Basic Research, projects nos. 19-02-00348 and 20-3270059, the Government of the Krasnoyarsk Territory and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activity, projects nos. 19-42-240011 and 18-42240014 "Single-Orbit Effective Model of an Ensemble of Spin-Polaron Quasiparticles in the Problem of Describing the Intermediate State and Pseudogap Behavior of Cuprate Superconductors,"and the Presidium of the Russian Academy of Sciences, program I.12 "Fundamental Problems of High-Temperature Superconductivity." S.V.A. thanks the Council for Grants of the President of the Russian Federation for Governmental Support of Young Russian Scientists, project no. MK-1641.2020.2 . - ISSN 1063-7834. - ISSN 1090-6460

РУБ Physics, Condensed Matter

Кл.слова (ненормированные):
superconducting nanowire -- spin-orbit coupling -- Majorana modes -- strong electron correlations
Аннотация: In the second order of the operator form of the perturbation theory, the effective interactions in a superconducting nanowire have been obtained at the strong electron correlations, when the spin-orbit coupling parameter is comparable with the hopping integral. Using the exact diagonalization technique, in short nanowires with the open boundary conditions at the strong Coulomb repulsion, the excitations corresponding to the Majorana edge states with the energy below the value of a bulk superconducting gap have been demonstrated.

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Публикация на русском языке Злотников, Антон Олегович. Эффективные взаимодействия, индуцированные спин-орбитальной связью в сверхпроводящих нанопроволоках в режиме сильных корреляций [Текст] / A. O. Злотников, С. В. Аксенов, М. С. Шустин // Физ. тверд. тела. - 2020. - Т. 62 Вып. 9. - С. 1447-1453

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

Доп.точки доступа:
Aksenov, S. V.; Аксенов, Сергей Владимирович; Shustin, M. S.; Шустин, Максим Сергеевич; Злотников, Антон Олегович; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-02-00348, 20-3270059]; Krasnoyarsk Territorial Foundation [19-42-240011, 18-42240014]; Government of the Krasnoyarsk Territory; Presidium of the Russian Academy of SciencesRussian Academy of Sciences [I.12]; Council for Grants of the President of the Russian Federation [MK-1641.2020.2]
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13.

Val'kov, V. V.
Symmetry properties of the phase of coexistence of superconductivity and antiferromagnetism in 2D systems with strong electron correlations / V. V. Val’kov, A. O. Zlotnikov // J. Surf. Invest. - 2016. - Vol. 10, Is. 1. - P. 58-67, DOI 10.1134/S1027451016010195. - Cited References: 33. - The work is supported by the Russian Foundation for Basic Research, project nos.13-02-00523 and 15-42-04372. A.O. Zlotnikov is also grateful for the Grant Program for Young PhDs supported by the President of the Russian Federation, project no. SP-1370.2015.5 . - ISSN 1027-4510
Кл.слова (ненормированные):
superconductivity -- antiferromagnetism -- two-dimensional systems -- strong electron correlations -- heavy fermions -- cerium-based intermetallic compounds -- periodic Anderson model
Аннотация: Using the diagram technique for Hubbard operators, the effect of quasi-two-dimensionality and hybridization of the 4f electrons of cerium ions and p electrons of indium ions on the properties of the antiferromagnetic, superconducting, and mixed phases in heavy-fermion intermetallic compounds of cerium is studied. It is shown that taking into account quasi-two-dimensionality, low-energy hybridization processes renormalize the antiferromagnetic and superconducting order parameters in the broken time-reversal symmetry phase. Estimates of the critical temperatures of antiferromagnetic ordering and Cooper instability, obtained by the developed approach, are in good agreement with experimental data for cerium-based intermetallic compounds. © 2016, Pleiades Publishing, Ltd.

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Публикация на русском языке Вальков, Валерий Владимирович. Симметрийные свойства фазы сосуществования сверхпроводимости и антиферромагнетизма в 2D системах с сильными электронными корреляциями [Текст] / В. В. Вальков, A. O. Злотников // Поверхность : Наука, 2016. - № 1. - С. 49-59

Доп.точки доступа:
Zlotnikov, A. O.; Злотников, Антон Олегович; Вальков, Валерий Владимирович
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14.

Val'kov, V. V.
Stability of the Coexistence Phase of Chiral Superconductivity and Noncollinear Spin Ordering with a Nontrivial Topology and Strong Electron Correlations / V. V. Val’kov, A. O. Zlotnikov // JETP Letters. - 2019. - Vol. 109, Is. 11. - P. 736-743, DOI 10.1134/S0021364019110158. - Cited References: 37. - We are grateful to M.S. Shustin for stimulating discussions. This work was supported by the Russian Foundation for Basic Research (project nos. 19-02-00348-а and 18-32-00443-mol-a); jointly by the Russian Foundation for Basic Research, the Government of Krasnoyarsk Region, and the Krasnoyarsk Region Science and Technology Support Fund (project no. 18-42-243002 “Manifestation of Spin–Nematic Correlations in Spectral Characteristics of the Electronic Structure and Their Effect on the Practical Properties of Cuprate Superconductors”); and by the Presidium of the Russian Academy of Sciences (program no. I.12 “Fundamental Problems of High-Temperature Superconductivity”). A.O.Z. acknowledges the support of the Council of the President of the Russian Federation for State Support of Young Scientists and Leading Scientific Schools (project no. MK-3594.2018.2). . - ISSN 0021-3640
Аннотация: It has been shown that quantum charge and spin fluctuations in a strongly correlated 2D system with a triangular lattice, significantly renormalizing the magnetic order parameter, do not destroy the coexistence phase of chiral d + id superconductivity and 120° spin ordering. The region of realization of nontrivial topology determined by the topological index N3 holds. It has been shown that edge states for the topologically non-trivial phase include a Majorana mode. The spatial structure of this mode has been determined. It has been found that spin and charge fluctuations shift the critical electron densities at which quantum topological transitions occur. It has been shown that an increase in the intersite Coulomb repulsion reduces the number of such transitions. © 2019, Pleiades Publishing, Inc.

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Публикация на русском языке Вальков, Валерий Владимирович. Устойчивость фазы сосуществования киральной сверхпроводимости и неколлинеарного спинового упорядочения с нетривиальной топологией при сильных электронных корреляциях [Текст] / В. В. Вальков, A. O. Злотников // Письма в ЖЭТФ. - 2019. - Т. 109 Вып. 11. - С. 769-777

Держатели документа:
Kirensky Institute of Physics, Federal Research Center KSC, Siberian Branch, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Zlotnikov, A. O.; Злотников, Антон Олегович; Вальков, Валерий Владимирович
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15.

Val'kov, V. V.
Splitting of the lower subband of Hubbard fermions in the Shubin-Vonsowsky model under the influence of strong intersite correlations / V. V. Val'kov, M. M. Korovushkin // J. Exp. Theor. Phys. - 2011. - Vol. 112, Is. 1. - P. 108-120, DOI 10.1134/S1063776110061056. - Cited References: 26. - We express our deep gratitude to R. O. Zaitsev for numerous remarks and discussions. We are grateful to A. A. Golovnya, A. A. Shklyaev, and V. A. Mitskan for specific advice on the numerical calculations of the mass operator. This work was supported by the "Quantum Condensed Matter Physics" Program of the Presidium of the Russian Academy of Sciences, the Russian Foundation for Basic Research (project no. 10-02-00251), the "Scientific and Scientific-Pedagogical Personnel of Innovational Russian for 2009-2013" Federal Goal-Oriented Program, and the Interdisciplinary Integration Project no. 53 of the Siberian Branch of the Russian Academy of Sciences. One of us (M. K.) thanks Lavrentiev's contest of youth projects of the Siberian Branch of the Russian Academy of Sciences. . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
NARROW ENERGY BANDS
ELECTRON CORRELATIONS
Кл.слова (ненормированные):
Cooper channels -- Cooper instability -- Density of electronic state -- Doping levels -- Electron concentration -- Energy structures -- Hubbard -- Hubbard operators -- Interaction energies -- Intersite correlation -- Mott-Hubbard insulator -- Nonuniform -- Renormalization -- Root mean squares -- Scattering amplitudes -- Spectral intensity -- Split-off band -- Strongly correlated fermions -- Sub-bands -- Doping (additives) -- Superconducting transition temperature
Аннотация: The diagram technique for Hubbard operators is used to investigate the influence of intersite Coulomb interactions on the energy structure and Cooper instability of strongly correlated fermions. Allowance for intersite correlations in doped Mott-Hubbard insulators is shown to lead to a splitting of the lower subband of Hubbard fermions and to the formation of a band of fluctuation states as soon as the intersite interaction energy becomes comparable to or exceeds the mean kinetic energy. The spectral intensity of the splitoff band is proportional to the root-mean-square fluctuation of the occupation numbers and increases with doping level. The predicted effect changes significantly the structure of the density of electronic states. This leads to a renormalization of the pole of the scattering amplitude in the Cooper channel and manifests itself as a nonuniform (in electron concentration) modification of the dependence of the critical superconducting transition temperature.

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Держатели документа:
[Val'kov, V. V.
Korovushkin, M. M.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Val'kov, V. V.] Reshetnev Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036, Russian Federation
Reshetnev Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Вальков, Валерий Владимирович
}
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16.

Val'kov, V. V.
Spin-Fluctuation Renormalization of the Temperature of a Superconducting s-Phase in Rare-Earth Intermetallides / V. V. Val'kov, D. M. Dzebisashvili // J. Exp. Theor. Phys. - 2008. - Vol. 107, Is. 4. - P. 679-691, DOI 10.1134/S1063776108100166. - Cited References: 34. - This study was supported in part by the Russian Foundation for Basic Research ( project no. 07-02-00226), the Department of Physic of the Russian Academy of Sciences ( within the program "Strongly Correlated Electrons in Semiconductors, Superconductors, and Magnetic Materials"), and the Siberian Branch of the Russian Academy of Sciences ( integration project no. 3.4). . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
HEAVY-FERMION SUPERCONDUCTORS
   PERIODIC ANDERSON MODEL
   WAVE SUPERCONDUCTIVITY
   PERTURBATION-THEORY
   MECHANISM
   VALENCE
   SYSTEMS
   LATTICE
   STATE
Кл.слова (ненормированные):
Differential equations -- Electric conductivity -- Green's function -- Numerical analysis -- Rare earth elements -- Spin dynamics -- Spin fluctuations -- Anomalous components -- Critical temperatures -- Experimental datums -- Infinite systems -- Numerical calculations -- Order parameters -- Periodic Anderson models -- Renormalization -- S-phase -- Skutterudite -- Strong electron correlations -- Sub systems -- Superconducting states -- Superconductivity
Аннотация: A theory of the superconducting state with s-type symmetry of the order parameter ( the transition to this state was observed in recently discovered heavy-fermion skutterudite LaFe(4)P(12)) is developed using the periodic Anderson model in the limit of strong electron correlations. Exact representations of Green's functions of the superconducting phase via the normal and anomalous components of the mass and strength operators are obtained. It is shown that an important role in the description of this superconducting phase is played by the anomalous components of the strength operator, which reflect spin-fluctuation processes in the localized subsystem. These components are calculated in the one-loop approximation using the solution of an infinite system of integral equations of self-consistency for the superconducting phase. Numerical calculations show that allowance for the process of scattering on spin fluctuations leads to renormalization of the critical temperature and provides agreement with the experimental data.

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Держатели документа:
[Val'kov, V. V.
Dzebisashvili, D. M.] Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
[Val'kov, V. V.
Dzebisashvili, D. M.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
[Val'kov, V. V.] 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
Siberian State Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Dzebisashvili, D. M.; Дзебисашвили, Дмитрий Михайлович; Вальков, Валерий Владимирович
}
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17.

Val'kov, V. V.
Renormalization of Energy Structure and Oscillation Period in the de Haas-van Alphen Effect at the Strong Intersite Coulomb Interaction / V. . Val'kov, M. . Korovushkin // J. Phys. Soc. Jpn. - 2011. - Vol. 80, Is. 1. - Ст. 14703. - P., DOI 10.1143/JPSJ.80.014703. - Cited References: 36. - This study was supported by the program "Quantum Physics of Condensed Matter'' of the Presidium of the Russian Academy of Sciences (RAS), the Russian Foundation for Basic Research (project No. 10-02-00251), the Federal goal-oriented program Scientific Brainpower of the Russian Innovations 2009-2013, and the Siberian Division of RAS (Interdisciplinary Integration project No. 53). One of the authors (M. K.) would like to acknowledge the support of the Lavrentiev's Competition of the Siberian Division of RAS. The authors are grateful to the Physical Society of Japan for financial support in publication. . - ISSN 0031-9015

РУБ Physics, Multidisciplinary
Рубрики:
T-C SUPERCONDUCTOR
   EXTENDED HUBBARD-MODEL
   CUPRATE SUPERCONDUCTORS
   ELECTRON CORRELATIONS
   QUANTUM OSCILLATIONS
   FERMI-SURFACE
   OXIDES
   TEMPERATURE
   STATE
   BANDS
Кл.слова (ненормированные):
strongly correlated electron systems -- cuprate superconductors -- intersite Coulomb interaction -- t-V model -- de Haas-van Alphen effect -- Cuprate superconductors -- De Haas-van Alphen effect -- Intersite Coulomb interaction -- Strongly correlated electron systems -- T-V model
Аннотация: The effect of strong intersite Coulomb correlations on the formation of the electron structure of the t-V model has been studied. A qualitatively new result indicating the occurrence of a split-off band of Fermi states has been obtained. The spectral intensity of this band increases with an increase in doping level and is determined by the mean-square fluctuation of occupation numbers. This results in the transformation of the energy structure and the integrated density of states and in a further decrease in state occupation in the quasimomentum space near the Fermi level as compared with Hubbard renormalization. It has been shown that this effect leads to an increase in the area of the quasimomentum space part limited by the Fermi contour and is important for the analysis of the de Haas-van Alphen oscillations in cuprate superconductors.

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Держатели документа:
[Val'kov, Valery
Korovushkin, Maxim] LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
[Val'kov, Valery] Siberian Aerosp Univ, Krasnoyarsk 660014, Russia
ИФ СО РАН
L. V. Kirensky Institute of Physics, Krasnoyarsk 660036, Russian Federation
Siberian Aerospace University, Krasnoyarsk 660014, Russian Federation

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Вальков, Валерий Владимирович
}
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18.

Val'kov, V. V.
Lower subband splitting and superconductivity of 2D Hubbard fermions with strong intersite correlations / V. V. Val'kov, M. M. Korovushkin // Bull. Russ. Acad. Sci. Phys. - 2012. - Vol. 76, Is. 2. - P. 133-135, DOI 10.3103/S1062873812020074. - Cited References: 6. - This study was supported by Quantum Physics of Condensed Matter program of the Presidium of the Russian Academy of Sciences; the Russian Foundation for Basic Research, project np. 10-02-00251; the federal target program Scientists and Science Teachers of an Innovate Russia, 2009-2013; the Siberian Branch of the Russian Academy of Sciences, complex integration project no. 53; RF Presidential Grant MK-1300.2011.2; and the Siberian Branch of the Russian Academy of Sciences' Lavrent'ev Competition for Young Scientists. . - ISSN 1062-8738
Кл.слова (ненормированные):
Coulomb correlations -- Doping levels -- Electron structures -- Fermi state -- Hubbard -- Intersite correlation -- Mean-square fluctuations -- Spectral intensity -- Split-off band -- Subbands -- Natural sciences
Аннотация: The effect of the strong intersite Coulomb correlations on the formation of an electron structure in the Shubin-Vonsowsky model in the regime of strong one-site correlations is studied. The results reveal a split-off band of the Fermi states. The spectral intensity of this band grows with the enhancement of the doping level and is determined by the mean-square fluctuation of occupation numbers. This changes the structure of the electron density of states qualitatively. © 2012 Allerton Press, Inc.

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Публикация на русском языке Вальков, Валерий Владимирович. Расщепление нижней подзоны и сверхпроводимость 2D-фермионов Хаббарда при сильных межузельных корреляциях [Текст] / В. В. Вальков, М. М. Коровушкин // Изв. РАН. Сер. физич. - 2012. - Т. 76 № 2. - С. 158-160

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Вальков, Валерий Владимирович; International Symposium "Nanophysics and Nanoelectronics-2011" (March 2011 ; Nizhni Novgorod)
}
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19.

Val'kov, V. V.
Influence of the Coulomb repulsions on the formation of the superconducting gap of the spin-polaron quasiparticles in cuprates / V. V. Val'kov, M. M. Korovushkin, A. F. Barabanov // J. Low Temp. Phys. - 2019. - Vol. 196, Is. 1-2. - P. 242–252, DOI 10.1007/s10909-018-02120-3. - Cited References: 26. - The work was supported by the program of the Presidium of the Russian Academy of Sciences No. 12 “Fundamental problems of high-temperature superconductivity,” the Russian Foundation for Basic Research (Projects Nos. 16-02-00304 and 18-02-00837) and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (Projects Nos. 18-42-243002 “Manifestation of spin-nematic correlations in spectral characteristics of electronic structure and their influence on practical properties of cuprate superconductors” and 18-42-243018 “Contact phenomena and magnetic disorder in the problem of the formation and detection of topological edge states in semiconductor nanostructures”), and the grant of the President of the Russian Federation (Project MK-1398.2017.2). . - ISSN 0022-2291. - ISSN 1573-7357
Кл.слова (ненормированные):
Cuprate superconductors -- Intersite Coulomb interaction -- Spin polarons -- Spin-charge correlations -- Unconventional superconductivity
Аннотация: Taking into account the real crystalline structure of the CuO2 plane and the strong spin-fermion coupling, the influence of the on-site Coulomb repulsion of holes Up and the intersite Coulomb repulsion V2 between holes located at the next-nearest-neighbor oxygen ions on the formation of the superconducting gap with the d-wave symmetry of the order parameter of the spin-polaron quasiparticles is studied. It is shown that the formation of the resulting superconducting gap within the spin-fermion model is caused by three components. The dependence of the narrowing of the superconducting gap on the values Up and V2 is analyzed.

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Держатели документа:
Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, Russia
Vereshchagin Institute for High Pressure Physics, Troitsk, Moscow, Russia

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Barabanov, A. F.; Вальков, Валерий Владимирович
}
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20.

Val'kov, V. V.
Energy structure of high-temperature superconductors with the intersite Coulomb interaction / V. V. Val'kov, M. M. Korovushkin // Eur. Phys. J. B. - 2009. - Vol. 69, Is. 2. - P. 219-227, DOI 10.1140/epjb/e2009-00141-4. - Cited References: 26. - This study was supported by the program "Quantum physics of condensed matter"of the Presidium of the Russian Academy of Sciences (RAS); the Russian Foundation for Basic Research (project no. 07-02-00226); the Siberian Branch of RAS (Interdisciplinary Integration project no. 53). One of authors (M. K.) would like to acknowledge the support of the Dynasty Foundation. . - ISSN 1434-6028

РУБ Physics, Condensed Matter
Рубрики:
HIGH-TC SUPERCONDUCTIVITY
   SINGLE-BAND
   ELECTRON CORRELATIONS
   CU OXIDES
   J MODEL
   DERIVATION
Кл.слова (ненормированные):
Strongly correlated electron systems; heavy fermions -- Narrow-band systems; intermediate-valence solids -- Cuprate superconductors -- Strongly correlated electron systems heavy fermions -- Narrow-band systems intermediate-valence solids -- Cuprate superconductors -- Emery model -- Energy structures -- Fermi state -- Integrated density -- Root mean squares -- Spectral intensity -- Copper compounds -- Corundum -- Coulomb interactions -- Electrons -- Fermions -- High temperature superconductors -- Oxide superconductors -- Superconductivity
Аннотация: The effect of the intersite Coulomb interaction of fermions on the ground state and energy structure of high-temperature superconductors is considered within the three-band Emery model using an extended basis of the irreducible operators orthogonal on Mori. The proposed theory allows prediction of bands of the fluctuation states whose spectral intensity grows with an increase in the root-mean-square fluctuations of the occupation numbers. The increase in these fluctuations in high-temperature superconductors upon doping plays a key role in redistribution of the integrated density of the Fermi states.

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Держатели документа:
[Val'kov, V. V.
Korovushkin, M. M.] RAS, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Val'kov, V. V.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
ИФ СО РАН
L.V. Kirensky Institute of Physics, Siberian Branch, RAS, Krasnoyarsk 660036, Russian Federation
Siberian Federal University, Krasnoyarsk 660041, Russian Federation

Доп.точки доступа:
Korovushkin, M. M.; Коровушкин, Максим Михайлович; Вальков, Валерий Владимирович; Russian Academy of Sciences; Russian Foundation for Basic Research [07-02-00226]; RAS; Dynasty Foundation
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