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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Вальков, Валерий Владимирович, Дзебисашвили, Дмитрий Михайлович
Заглавие : Особенности спектра тяжелых фермионов в скошенной фазе антиферромагнитных интерметаллидов
Место публикации : Теоретическая и математическая физика. - Москва: Математический институт им. В.А. Стеклова РАН, 2010. - Т. 162, № 1. - С. 125-149. - ISSN 0564-6162, DOI 10.4213/tmf6460. - ISSN 2305-3135(eissn)
Предметные рубрики:
Ключевые слова (''Своб.индексиров.''): периодическая модель андерсона--тяжелые фермионы--антиферромагнетизм--скошенная фаза
Аннотация: Изучено влияние индуцированного магнитным полем скоса магнитных подрешеток на энергетическую структуру тяжелофермионных квазичастиц в интерметаллидах с антиферромагнитным типом упорядочения. Исследования выполнены в рамках эффективного гамильтониана периодической модели Андерсона в режиме сильных электронных корреляций. В результате учета виртуальных забросов в высокоэнергетические двоечные состояния этот гамильтониан включает обменные взаимодействия между спиновыми моментами f-ионов, а также s–f-обменную связь между двумя подсистемами. Для неколлинеарной геометрии задачи введено унитарное преобразование, позволившее свести уравнение восьмой степени для спектра тяжелых фермионов к двум уравнениям четвертой степени. Показано, что характер квазиимпульсной зависимости энергии тяжелых фермионов претерпевает качественные изменения при переходе от антиферромагнитной фазы к фазе со значительным углом скоса, возникающим при наложении внешнего магнитного поля.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Вальков, Валерий Владимирович, Злотников, Антон Олегович
Заглавие : Сосуществование сверхпроводимости и антиферромагнетизма в тяжелофермионных интерметаллидах
Место публикации : Теор. и мат. физика. - 2013. - Т. 174, № 3. - С. 484-503. - DOI 10.4213/tmf8378
Аннотация: В рамках эффективного гамильтониана для периодической модели Андерсона при использовании двухвременных запаздывающих функций Грина изучены условия реализации фазы сосуществования сверхпроводимости и антиферромагнетизма. Такая фаза экспериментально наблюдается в редкоземельных интерметаллидах с тяжелыми фермионами при приложении внешнего давления. В выбранной модели при наличии дальнего антиферромагнитного упорядочения куперовская неустойчивость индуцируется в результате совместного влияния сверхобменного взаимодействия в подсистеме локализованных электронов и гибридизации между двумя группами электронов. Приложение внешнего давления вызывает увеличение энергии локализованного уровня, сопровождающееся в определенной области фазовой диаграммы резким разрушением дальнего антиферромагнитного упорядочения. В точке разрушения сверхпроводящий параметр порядка обладает максимальным значением. Показано, что уменьшение намагниченности антиферромагнитной подрешетки с ростом давления вызывает значительное увеличение массы фермиевских квазичастиц, а в критической точке происходит изменение знака носителей тока. Полученные результаты на качественном уровне хорошо согласуются с экспериментальными данными для тяжелофермионного интерметаллида CeRhIn5
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3.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Вальков, Валерий Владимирович, Дзебисашвили, Дмитрий Михайлович, Барабанов А. Ф.
Заглавие : d-Волновое спаривание спин-поляронных квазичастиц в спин-фермионной модели электронного строения CuO2-плосксти
Коллективы : Южный федеральный университет, "Порядок, беспорядок и свойства оксидов", международный междисциплинарный симпозиум (17; 2014 ; 5-10 сент.; Ростов-на-Дону/ Южный, Ростовская обл.)
Место публикации : XVII межд. симп. "Порядок, беспорядок и св-ва оксидов" (ODPO-17)/ чл. межд. прогр. ком. В. В. Вальков. - 2014. - Вып. 17, Т. 1. - С. 399-403
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Generalized Kondo lattice model and its spin-polaron realization by the projection method for cuprates
Коллективы : Russian Foundation for Basic Research [16-02-00073, 16-02-00304, 16-42-240435]; Siberian Branch of the Russian Academy of Sciences (Complex Program) [II.2P, 0358-2015-0005]
Место публикации : Theor. Math. Phys.: MAIK Nauka-Interperiodica / Springer, 2017. - Vol. 191, Is. 2. - P.752-763. - ISSN 0040-5779, DOI 10.1134/S0040577917050142. - ISSN 1573-9333(eISSN)
Примечания : Cited References:35. - This research was supported by the Russian Foundation for Basic Research (Grant No. 16-02-00073, 16-02-00304, and 16-42-240435) and the Siberian Branch of the Russian Academy of Sciences (Complex Program No. II.2P, Grant No. 0358-2015-0005).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
HIGH-TC SUPERCONDUCTORS
COPPER OXIDES
Ключевые слова (''Своб.индексиров.''): strong electron correlation--spin-fermion model--kondo lattice model--spin polaron
Аннотация: The spin-fermion model, which is an effective low-energy realization of the three-band Emery model after passing to the Wannier representation for the px and py orbitals of the subsystem of oxygen ions, reduces to the generalized Kondo lattice model. A specific feature of this model is the existence of spin-correlated hoppings of the current carriers between distant cells. Numerical calculations of the spectrum of spin-electron excitations highlight the important role of the long-range spin-correlated hoppings.
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5.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : The influence of spin and charge fluctuations on the coexistence phase of superconductivity and antiferromagnetism in heavy-fermion Ce-based compounds
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.O2.3. - P.136. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 2. - This study was funded by the Program of SB RAS 0358-2015-0002 and RFBR project No. 16-02-00073-a. A.O.Z. is grateful for support of the Grant of the President of the Russian Federation SP-1370.2015.5.
Ключевые слова (''Своб.индексиров.''): heavy fermions--antiferromagnetism--superconductivity--ginzburg-landau theory
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Spin-polaron nature of fermion quasiparticles and their d-wave pairing in cuprate superconductors
Место публикации : JETP Letters. - 2016. - Vol. 104, Is. 10. - P.730-741. - ISSN 00213640 (ISSN), DOI 10.1134/S002136401622015X
Примечания : Cited References: 52
Аннотация: In the framework of the spin-fermion model, to which the Emery model is reduced in the limit of strong electron correlations, it is shown that the fermion quasiparticles in cuprate high-Tcsuperconductors (HTSCs) arise under a strong effect of exchange coupling between oxygen holes and spins of copper ions. This underlies the spin-polaron nature of fermion quasiparticles in cuprate HTSCs. The Cooper instability with respect to the d-wave symmetry of the order parameter is revealed for an ensemble of such quasiparticles. For the normal phase, the spin-polaron concept allows us to reproduce the fine details in the evolution of the Fermi surface with the changes in the doping level x observed in experiment for La2-xSrxCuO4. The calculated T–x phase diagram correlates well with the available experimental data for cuprate HTSCs. © 2016, Pleiades Publishing, Inc. All Right Reserved.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Spin-Fluctuation Renormalization of the Temperature of a Superconducting s-Phase in Rare-Earth Intermetallides
Коллективы :
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 107, Is. 4. - P679-691. - ISSN 1063-7761, DOI 10.1134/S1063776108100166
Примечания : 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).
Предметные рубрики: HEAVY-FERMION SUPERCONDUCTORS
PERIODIC ANDERSON MODEL
WAVE SUPERCONDUCTIVITY
PERTURBATION-THEORY
MECHANISM
VALENCE
SYSTEMS
LATTICE
STATE
Ключевые слова (''Своб.индексиров.''): 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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8.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : Spin wave theory of heavy-fermion antiferromagnets in the framework of the periodic anderson model
Коллективы : "Spin Waves", International Simposium, Физико-технический институт им. А.Ф. Иоффе РАН
Место публикации : Spin Waves 2015, Int. Symp.: abstracts. - СПб., 2015
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Properties of the heavy-fermion spectrum in the canted phase of antiferromagnetic intermetallides
Коллективы :
Место публикации : Theor. Math. Phys.: SPRINGER, 2010. - Vol. 162, Is. 1. - P106-125. - ISSN 0040-5779, DOI 10.1007/s11232-010-0008-4
Примечания : Cited References: 23. - This paper was supported by the Russian Foundation for Basic Research (Grant No. 07-02-00226), the Siberian Branch, Russian Academy of Sciences (Integrated Project No. 53), and the program "Strong Electron Correlations" of the Physics Division, Russian Academy of Sciences.
Предметные рубрики: PERIODIC ANDERSON MODEL
KONDO-LATTICE
VALENCE
Ключевые слова (''Своб.индексиров.''): periodic anderson model--heavy fermion--antiferromagnetism--canted phase--antiferromagnetism--canted phase--heavy fermion--periodic anderson model
Аннотация: We study the effect of the magnetic-field-induced canting of magnetic sublattices on the energy structure of heavy fermion quasiparticles in intermetallides with antiferromagnetic-type ordering. We work in the framework of an effective Hamiltonian of the periodic Anderson model in the regime of strong electron correlations. With the virtual transfers into high-energy double states taken into account, this Hamiltonian involves exchange interactions between spin moments of the f ions and the s-f-exchange coupling between the two subsystems. For a noncollinear problem geometry, we introduce a unitary transformation that allows reducing an eighth-order equation for the spectrum of heavy fermions to two fourth-order equations. We show that the quasimomentum dependence of the heavy-fermion energy changes qualitatively under the transition from the antiferromagnetic phase to a phase with a considerable canting angle emerging in an external magnetic field.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Origin of the spin polaron quasiparticles and their cooper instability in High-Tc superconductors
Коллективы : Russian Foundation for Basic Research [13-02-00523, 13-02-00909]; Dynasty Foundation
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1049-1055. - ISSN 1557-1939, DOI 10.1007/s10948-016-3383-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:15. - This study was supported by the Russian Foundation for Basic Research, projects nos. 13-02-00523, 13-02-00909 and the Dynasty Foundation.
Предметные рубрики: Model
State
Ключевые слова (''Своб.индексиров.''): cuprate high-t-c superconductors--spin polarons--spin-fermion model
Аннотация: IIn the framework of the spin-fermion model, it is shown that accounting for the strong spin-charge fluctuations between holes of copper and oxygen ions in cuprate High-T c superconductors leads to the formation of the Fermi spin-polaron quasiparticles. It is demonstrated that the large value of the binding energy of such quasiparticle is determined by the processes in which hopping intensity of the oxygen holes depends significantly on the spin configuration of holes on the copper and oxygen ions. It was found that the ensemble of such quasiparticles manifests Cooper instability and the concentration dependence of the critical temperature is in good agreement with the experimental data.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : On the s-type superconductivity in heavy-fermion compounds
Место публикации : JETP Letters. - 2006. - Vol. 84, Is. 4. - P.217-221. - ISSN 0021-3640, DOI 10.1134/S0021364006160119
Примечания : Cited References: 8
Аннотация: The amplitude of scattering of f electrons has been calculated for the periodic Anderson model in the strong-correlation limit (U = infinity) in the Cooper channel. From the condition of the existence of a pole of this amplitude, an equation is derived for determining the critical temperature (T-c) of the transition to the superconducting phase with the s symmetry of the order parameter. The temperature T-c as a function of the electron density and hybridization parameter has been calculated by self-consistently solving the system of equations. The region of the existence of the superconducting phase is found to adjoin the region of the existence of the unsaturated ferromagnetic state and does not overlap it. The results can be used to describe the transition to the superconducting phase with the s symmetry of the order parameter in heavy-fermion skutterudite LaFe4P12. In this case, the inclusion of the scattering of fermions by spin fluctuations turns out to be substantial enough to obtain T-c values close to the experimental data.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : On the implementation of the coexistence phase of antiferromagnetism and superconductivity in heavy-fermion intermetallides
Место публикации : JETP Letters. - 2012. - Vol. 95, Is. 7. - P.350-356. - ISSN 0021-3640, DOI 10.1134/S0021364012070089
Примечания : Cited References: 29. - This work was supported by the Presidium of the Russian Academy of Sciences (program "Quantum Mesoscopic and Disordered Structures"), the Russian Foundation for Basic Research (project nos. 10-02-00251 and 11-02-98007-Siberia), and the Ministry of Education and Science of the Russian Federation (federal program "Human Capital for Science and Education in Innovative Russia" for 2009-2013).
Предметные рубрики: QUANTUM-CRITICAL-POINT
CRITICAL PRESSURE
CERHIN5
LATTICE
Аннотация: The region of the state diagram in which the pressure-induced quantum phase transition occurs with the destruction of the antiferromagnetic ordering and the appearance of the superconductivity has been described within the periodic Anderson model. It has been shown that a microscopically homogeneous coexistence phase of antiferromagnetism and superconductivity is implemented in the vicinity of the critical point, which was experimentally found in the heavy-fermion compound CeRhIn5. In this region, the pressure increase is accompanied by the experimentally observed strong growth of the effective fermion mass.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M., Barabanov A. F.
Заглавие : Nature of Cooper instability of spin polarons in cuprate high-Tc superconductors
Коллективы : Russian Foundation for Basic Research [13-02-00523, 13-02-00909], Dynasty Foundation
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2015. - Vol. 181, Is. 3-4. - P.134-138. - ISSN 0022, DOI 10.1007/s10909-015-1331-9. - ISSN 15737357(eISSN)
Примечания : Cited References:10. - This study was supported by the Russian Foundation for Basic Research, Projects Nos. 13-02-00523, 13-02-00909 and the Dynasty Foundation.
Предметные рубрики: OXIDES
MODEL
Ключевые слова (''Своб.индексиров.''): high-t-c superconductors--spin polarons--spin-fermion model
Аннотация: It is shown that the exchange interaction in the subsystem of localized moments of copper ions can trigger a Cooper instability in the ensemble of spin-polaron quasiparticles in cuprate high-temperature superconductors. It is important that, inherent to cuprates, strong coupling between Fermi and spin degrees of freedom leads on the one hand to formation of spin-polaron quasiparticles and, on the other hand, allows to transfer the interaction between Bose degrees of freedom onto the interaction between Fermi quasiparticles. The solution of the integral equation for the d-wave superconducting order parameter is well consistent with the available experimental data.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Mitskan V. A., Shustin M. S.
Заглавие : Ground-State Fermion Parity and Caloric Properties of a Superconducting Nanowire
Место публикации : J. Exp. Theor. Phys. - 2019. - Vol. 129, Is. 3. - P.426-437. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776119080144
Примечания : Cited References: 74. - This work was supported by the Russian Foundation for Basic Research (project nos. 16-02-00073, 18-32-00443, 18-42-243017, 18-42-243018), the Government of the Krasnoyarsk Kray, the Krasnoyarsk Kray Science Foundation within the scientific projects “Contact Phenomena and Magnetic Disorder in the Formation and Detection of Topologically Protected Edge States in Semiconductor Nanostructures” (project no. 18-42-243018), “Manifestation of Coulomb Interactions and Bounded-Geometry Effects in the Properties of Topological Edge States of Nanostructures with Spin–Orbit Interactions” (project no. 18-42-243017). One of us (Sh. M. S.) thanks the Council for Grants of the Russian President (project nos. MK-3594.2018.2 and MK-3722.2018.2).
Аннотация: Abstract: The ground-state structure and fermion parity have been determined for a semiconductor nano-wire with a strong Rashba spin–orbit interaction and proximity-induced superconductivity placed in an external magnetic field under periodic boundary conditions. Allowance for the open boundaries is shown to cause the topologically nontrivial parameter region to be partitioned into a set of subregions with a different ground-state fermionic parity. This peculiarity is related to the emergence of edge modes with nonmonotonically changing excitation energies in the system as its parameters change. At the quantum transition point, at which the ground-state fermionic parity changes, the edge-mode energy is zero. The magneto- and electrocaloric effects are shown to be effective characteristics that allow the series of quantum transitions in an open nanowire to be identified experimentally. These effects at low temperatures exhibit an anomalous behavior in the parameter region for which topologically stable Majorana modes are realized in long nanowires. © 2019, Pleiades Publishing, Inc.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Fedoseev A. D.
Заглавие : Fano antiresonance induced by the rashba spin-orbit coupling in systems with conduction channels exhibiting the points of nonanalyticity in fermion paths
Коллективы : Russian Foundation for Basic Research [16-42-242036, 16-42-243056, 17-42-240441]; Government of the Krasnoyarsk Territory; Krasnoyarsk Region Science and Technology Support Fund [21/16, 29/16, 02/17]
Место публикации : JETP Letters. - 2017. - Vol. 106, Is. 5. - P.302-307. - ISSN 0021-3640, DOI 10.1134/S0021364017170131. - ISSN 1090-6487(eISSN)
Примечания : Cited References:17. - This work was funded by the Russian Foundation for Basic Research (project nos. 16-42-242036, 16-42-243056, and 17-42-240441), Government of the Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the Research (project nos. 21/16, 29/16, and 02/17).
Аннотация: It is shown that the combined effect of the nonanalyticity of the channel for the motion of charge carriers and the Rashba spin-orbit coupling induces resonant anomalies in the transport characteristics of nanosystems related to the size quantization. When the characteristic length determined by the ratio of the hopping integral and the spin-orbit coupling constant coincides with the distance between the points of nonanalyticity, the size effect arises in the channel. It manifests itself in the complete reflection from the device, which can be treated as the Fano antiresonance. The current-voltage characteristics of the nanosystem with the nonanalytical channel undergo significant changes at slight variations of the spin-orbit coupling constant near its critical value.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Electron spectrum and heat capacity of heavy fermions in the canted phase of antiferromagnetic intermetallides
Коллективы :
Место публикации : J. Exp. Theor. Phys. - 2010. - Vol. 110, Is. 2. - P.301-318. - ISSN 1063-7761, DOI 10.1134/S1063776110020147
Примечания : Cited References: 41. - This study was supported by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences, interdisciplinary integration project no. 53 of the Siberian Branch of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 07-02-00226).
Предметные рубрики: PERIODIC ANDERSON MODEL
PRESSURE-INDUCED SUPERCONDUCTIVITY
KONDO-LATTICE
FERROMAGNETISM
FLUCTUATIONS
COEXISTENCE
CERHIN5
SYSTEMS
DIAGRAM
CENISN
Ключевые слова (''Своб.индексиров.''): antiferromagnetic phase--antiferromagnetics--antiferromagnets--electron spectrum--electronic heat capacity--energy spectra--experimental data--external magnetic field--heat capacities--heavy fermion--low temperatures--magnetic sublattices--magnetic subsystems--sommerfeld constant--structural rearrangement--temperature dependence--antiferromagnetism--cerium--cerium compounds--fermions--magnetic fields--phase transitions--specific heat--spectroscopy--antiferromagnetic materials
Аннотация: The energy spectrum of heavy fermions in an external magnetic field is calculated for canted magnetic sublattices of antiferromagnetic intermetallides. This makes it possible to determine low-temperature features of electronic heat capacity of heavy-fermion antiferromagnets with the metal-type ground state taking into account the structural rearrangement of the magnetic subsystem. The calculated temperature dependences of the magnetization, heat capacity, and Sommerfeld constant in the vicinity of the point of transition to the antiferromagnetic phase correlate with experimental data obtained for heavy-fermion antiferromagnets PuGa3, Ce2Au2Cd, YbNiSi3, and PuPd5Al2.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : EFFECTIVE INTERACTIONS IN THE PERIODIC ANDERSON MODEL IN THE REGIME OF MIXED VALENCY WITH STRONG CORRELATIONS
Коллективы :
Разночтения заглавия :авие SCOPUS: Effective interactions in the periodic Anderson model in the regime of mixed valency with strong correlations
Место публикации : Theor. Math. Phys.: SPRINGER, 2008. - Vol. 157, Is. 2. - P1565-1576. - ISSN 0040-5779, DOI 10.1007/s11232-008-0130-8
Примечания : Cited References: 19. - This work was supported in part by the Russian Foundation for Basic Research (Grant No. 07-02-00226), a program of the Branch of Physical Sciences, Russian Academy of Sciences, and the "Integration Project" of the Siberian Branch, Russian Academy of Sciences.
Предметные рубрики: LATTICE
Ключевые слова (''Своб.индексиров.''): periodic anderson model--mixed valency--heavy fermion--effective hamiltonian--superconductivity--effective hamiltonian--heavy fermion--mixed valency--periodic anderson model--superconductivity
Аннотация: For the periodic Anderson model in the strong correlation regime, we construct the effective Hamiltonian H(eff) up to terms of the fourth order in the parameter V/U, where V is the hybridization interaction intensity and U is the intra-atom Coulomb repulsion strength. This Hamiltonian contains interactions inducing both magnetic ordering and Cooper instability under conditions of a mixed valency of rare-earth ions. Based on numerical calculations, we obtain information about the dependences of the effective interaction parameters on the distance between crystal lattice sites. We demonstrate that realizing exchange interactions corresponds to a strongly frustrated system of localized spin moments and facilitates the suppression of the antiferromagnetic order parameter with a possible transition to the state of a quantum spin liquid. It is essential that among the terms in H(eff) inducing the transition to the superconductivity phase, there are terms resulting in the d-type symmetry of the superconductivity order parameter; such a symmetry is realized in many heavy-fermion compounds.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Fedoseev A. D.
Заглавие : Effect of total reflection from a symmetric two-channel device with fermion path nonanalyticity points induced by Rashba spin-orbit coupling
Место публикации : Bull. Russ. Acad. Sci. Phys. - 2018. - Vol. 82, Is. 5. - P.550-553. - ISSN 10628738 (ISSN), DOI 10.3103/S1062873818050313
Примечания : Cited References: 8. - The reported study was funded by Russian Foundation for Basic Research (project nos. 16-42-242036, 16-42-243056, and 17-42-240441), Government of Krasnoyarsk Territory, and Krasnoyarsk Region Science and Technology Support Fund to the research (project nos. 22/17, 24/17, and 02/17).
Ключевые слова (''Своб.индексиров.''): electron transport--nonanalyticity--rashba spin-orbit coupling--regular polygon--spin-orbit couplings--symmetric systems--total reflection--transmission coefficients
Аннотация: The effect Rashba spin-orbit coupling has on transmission coefficient through a symmetric system with fermion path nonanalyticity points is illustrated using the example of a regular polygon-shaped chain. It is shown that the current passage through a device is blocked at the critical spin-orbit coupling values determined by the system’s geometry. At the near-critical spin-orbit coupling values, electron transport is possible only in a narrow range of energies.
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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : Dynamicalmagnetic susceptibility in the spin-fermion model for cuprate superconductors
Коллективы : 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
Место публикации : Theor. Math. Phys. - 2017. - Vol. 193, Is. 3. - P.1853-1864. - ISSN 0040-5779, DOI 10.1134/S004057791712011X. - ISSN 1573-9333(eISSN)
Примечания : 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).
Предметные рубрики: T-J MODEL
LONG-RANGE-ORDER
POLARON
CUO2
EXCITATIONS
LATTICE
WAVE
Ключевые слова (''Своб.индексиров.''): 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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