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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Астахов, Александр Михайлович, Дюгаев, Константин Петрович, Кузубов, Александр Александрович, Наслузов, Владимир Александрович, Васильев, Александр Дмитриевич, Бука, Эдуард Станиславович
Заглавие : Теоретическое исследование строения нитриминов. I. структура 2-нитрогуанидина и его алкилпроизводных
Место публикации : Журнал структурной химии. - Новосибирск: Изд-во СО РАН, 2009. - Т. 50, № 2. - С. 216-226. - ISSN 0136-7463
ГРНТИ : 31.15
УДК : 544.144.2 + 544.183 + 547.495.9
Ключевые слова (''Своб.индексиров.''): энергоемкие соединения--нитримины--energetic compounds--nitrimines--nitroguanidine--molecular structure--bond lengths--bond angles--quantum-chemical calculations--нитрогуанидин--строение молекул--длины связей--валентные углы--квантово-химические расчеты
Аннотация: Молекулярная структура 2-нитрогуанидина и его 1-метил-, 1-этил- и 1,1,3,3-тетраметил-производных изучена расчетными методами квантовой химии. Полученные результаты сравниваются с рентгеноструктурными данными. Показано, что увеличение базиса выше 6-31G, использование поляризационных функций и учет электронной корреляции не улучшает приближения к экспериментальным данным. Главной причиной этого является значительное влияние кристаллического поля на молекулярные геометрические параметры.The molecular structure of 2-nitroguanidine and its 1-methyl, 1-ethyl, and 1,1,3,3-tetramethyl derivatives was studied by quantum-chemical methods. The results were compared with X-ray data. Using a basis larger than 6-31G and polarization functions and including electron correlation in calculations did not improve agreement with experiment. The major reason for this is the considerable effect of the crystal field on the geometrical parameters of the molecules.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Pavlovskii M. S.
Заглавие : Lattice dynamics of BiFeO3: The untypical behavior of the ferroelectric instability under hydrostatic pressure
Место публикации : JETP Letters. - 2008. - Vol. 87, Is. 6. - P.288-291. - ISSN 0021-3640, DOI 10.1134/S0021364008060052
Примечания : Cited References: 15
Предметные рубрики: AB-INITIO CALCULATIONS
PEROVSKITE
Аннотация: Within a nonempirical model of an ionic crystal with the inclusion of the dipole and quadrupole ion polarizations, the lattice vibrational frequencies, high-frequency dielectric constant, Born dynamic charges, and the elasticity moduli of the BiFeO3 crystal have been calculated and their dependencies on the hydrostatic pressure in the cubic, rhombic, and rhombohedral phases have been determined. The results indicate the presence of the ferroelectric instability, which depends weakly on the pressure in all of the phases investigated. The dependence of the crystal lattice dynamics on the applied pressure for the cubic phases of BiAlO3, BaTiO3, and PbTiO3 has been calculated for comparison.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N.
Заглавие : The spin-state transition in ACo2O4 spinels (A = Be, Mg, Ca, Cd, Zn)
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 552. - Ст.169206. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169206
Примечания : Cited References: 51. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects № 19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic Mn+1AXn (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: The magnetic and electronic properties of the Co-based spinel oxides ACo2O4 (A = Be, Mg, Ca, Zn, Cd) were studied within GGA + U approach. It was found that the Co3+ ion is in a low-spin state due to the effect of the crystal field of octahedral symmetry. It is shown that Co3+ ion undergoes a spin-state transition into the high-spin state under the critical pressure of P = −10 GPa – −20 GPa. This pressure-induced spin-state transition is caused by the redistribution of electrons between the t2g- and eg-orbitals arising with increasing interatomic distances. The role of interatomic distances between Co3+ ion and its ligands is discussed. Thin-film form also favors the appearance of a high-spin state of Co3+ ion. At the same critical pressure, there is a sharp increase in the majority spin bandgap and a sharp decrease in the minority spin bandgap. These findings allow manipulating the spin state of Co3+ ions and bandgap width through the pressure or strain arising in thin films.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S.
Заглавие : The magnetic, electronic, optical, and structural properties of the AB2O4 (A = Mn, Fe, Co; B = Al, Ga, In) spinels: Ab initio study
Место публикации : J. Magn. Magn. Mater. - 2021. - Vol. 533. - Ст.168015. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2021.168015
Примечания : Cited References: 38. - The reported study was funded by Russian Foundation for Basic Research , Government of Krasnoyarsk Territory , Krasnoyarsk Regional Fund of Science to the research project № 19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: The effect of cation composition on the magnetic, electronic, optical, and structural properties of the spinel oxides AB2O4 (A = Fe, Mn, Co; B = Al, Ga, In) were studied within DFT-GGA + U approximation. The spinels were considered both in the normal and inverse structure. FeB2O4 (B = Al, Ga, In) spinels have an inverse structure, whereas AB2O4 (A = Mn, Co; B = Al, Ga, In) prefer a normal structure. We find that the studied spinels are antiferromagnetic materials with the composition-dependent bandgap. The bandgap width is determined by the minimum of the conductive s-band formed by B-site cations states and can be increased by the applied pressure. The microscopic mechanisms of the relationship between composition, structural and electronic properties are analyzed. The ability to manipulate the structural, electronic, and optical properties is attributed to the different s-orbital energies and sizes of the B-site cations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Matsynin A. A.
Заглавие : The effect of the impurities on the magnetic, electronic and optical properties of Mn5Ge3
Место публикации : Chin. J. Phys. - 2020. - Vol. 68. - P.9-18. - ISSN 05779073 (ISSN), DOI 10.1016/j.cjph.2020.06.027
Примечания : Cited References: 29. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects № № 19-42-240016 : «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and 18-42-243009: «New magnetic film nanocomposites based on layered GeO/Mn systems: synthesis, experimental and theoretical study of structural and magnetic properties». The calculations were performed with the computer resources of "Complex modeling and data processing research installations of mega-class" SRC "Kurchatovsky Institute” ( http://ckp.urcki.ru )
Аннотация: Earlier, we experimentally showed a significant effect of oxygen on the magnetic and structural properties of Mn5Ge3 due to the formation of a Nowotny phase of Mn5Ge3Ox. Here, in continuation of this study, we present a theoretical study of the magnetic and electronic properties of Mn5Ge3 and Mn5Ge3Dx (D = B, C, O). It was found that hexagonal Mn5Ge3 is a ferromagnetic metal with two nonequivalent manganese atoms in the structure. Our ab initio calculations also predict the existence of a spin-crossover in Mn5Ge3 under pressure. Impurities reduce saturation magnetization and electrical and thermal conductivity; however, the magnetic susceptibility and Curie temperature increase. Microscopic mechanisms of the effect of the impurities on the magnetic and electronic properties Mn5Ge3 are discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zamkova N. G., Draganyuk O. N.
Заглавие : The arising of ferromagnetism in Al-doped Mn2(Ga1−xAlx)C MAX phases
Колич.характеристики :5 с
Место публикации : J. Magn. Magn. Mater. - 2024. - Vol. 601. - Ст.172193. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2024.172193. - ISSN 18734766 (eISSN)
Примечания : Cited References: 30. - The study was funded by a grant from the Russian Science Foundation # 23-22-10020 https://rscf.ru/project/23-22-10020/, Krasnoyarsk Regional Fund of Science. The calculations were performed with the computer resources of "Complex modeling and data processing research installations of mega-class" SRC "Kurchatovsky Institute" (http://ckp.urcki.ru). The ternary phase diagrams for the calculation of formation enthalpies were taken from Materials Project (https://materialsproject.org) and OQMD (https://oqmd.org/) databases
Аннотация: The magnetic properties of ordered MAX phases Mn2(AlxGa1−x)C (x = 0.125, 0.25, 0.5, 0.75 and 0.875) have been studied within the DFT-GGA. We have found that increase of Al atom at A-site leads to the formation of the ferromagnetic phase with large magnetization of about 3.6 μB/f.u. The investigation of the phase stability is performed by comparing the total energy of the MAX phases with that of a set of competitive phases for calculation of the phase formation enthalpy. Up to a concentration of Al atoms x = 0.7 the compound remains thermodynamically stable. The exchange constants analysis shows the crucial role of exchange interactions between manganese atoms along the c-axis in forming of ferromagnetism. The magnetic transition temperature of Mn2(AlxGa1−x)C alloys increases with increase of the aluminum concentration.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zhandun V. S., Kazak N. V.
Заглавие : Orthogonal magnetic structures of Fe5O6: representation analysis and DFT calculations
Коллективы : International Baltic Conference on Magnetism, Балтийский федеральный университет им. И. Канта
Место публикации : V International Baltic Conference on Magnetism. IBCM: Book of abstracts. - 2023. - P.172
Примечания : Cited References: 4. - РФФИ № 21-52-12033
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zhandun V. S., Kazak N. V.
Заглавие : Orthogonal magnetic structures of Fe5O6: representation analysis and DFT calculations
Коллективы : Samarkand International Symposium on Magnetism, Samarkand State University
Место публикации : Book of abstacts of Samarkand International Symposium on Magnetism (SISM-2023)/ int. adv. com. S. G. Ovchinnikov [et al.]. - 2023. - Ст.2PO-L1-18. - P.62. - ISBN 978-5-00202-320-2
Примечания : РФФИ № 21-52-12033. - Cited References: 4. - РФФИ № 21-52-12033
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Kazak N. V., Vasiukov D. M.
Заглавие : Magnetic structure of Fe5O6: Group-theoretical analysis and DFT calculations
Колич.характеристики :5 с
Место публикации : JETP Lett. - 2024. - Vol. 119, Is. 4. - P.294-298. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364023604244. - ISSN 10906487 (eISSN)
Примечания : Cited References: 27. - V. Zhandun and N. Kazak acknowledge the support of the Russian Science Foundation (project no. 21-52-12033) and D. Vasiukov acknowledges the support of the Swedish Research Council (project no. 2018-04704)
Аннотация: The magnetic structure of Fe5O6 is studied using a combination of the group-theoretical analysis and DFT + U calculations of the electronic spectrum. The calculations are performed for the magnetic k = (0, 0, 0) vector. The magnetic ground state corresponds to the orthogonal ordering of two magnetic subsystems: the magnetic moments of Fe2+/Fe3+ ions located at the octahedral sites (slabs of octahedra) are directed along the c axis and are antiferromagnetically ordered, whereas the magnetic moments of Fe2+ ions in trigonal prisms forming one-dimensional chains are directed along the b axis and are antiferromagnetically coupled along the c axis. The formation of a nonzero antiferromagnetic component of magnetic moments in the slabs of octahedra directed along the b axis is caused by the effect of magnetic chains on the three-dimensional magnetic structure.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N., Zamkova N. G.
Заглавие : Magnetic structure and pressure-induced spin-crossover in Me3B2O6 (Me = Mn, Fe, Co, Ni) kotoites: Representation analysis and DFT calculations
Колич.характеристики :10 с
Место публикации : Comput. Mater. Sci. - 2024. - Vol. 236. - Ст.112859. - ISSN 09270256 (ISSN), DOI 10.1016/j.commatsci.2024.112859. - ISSN 18790801 (eISSN)
Примечания : Cited References: 25. - The study was funded by a grant from the Russian Science Foundation # 22-22-20024 https://rscf.ru/project/22-22-20024/, Krasnoyarsk Regional Fund of Science. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru). VZ thanks Dr. Natalia Kazak and Oksana Draganyuk for help in preparing the manuscript, useful discussions and valuable advices
Аннотация: The magnetic and electronic properties of transition metal borates Me3B2O6 (Me = Mn, Fe, Co, Ni) with kotoite structure have been investigated at ambient and high pressures via a combination of representation analysis and density functional theory (DFT + U) calculations. Several magnetic configurations corresponding to the different irreducible representations have been considered. The total-energy calculations reveal that the magnetic ground state of Me3B2O6 kotoites is composition-dependent. The lowest energy magnetic phase of manganese and nickel kotoites is characterized by the antiferromagnetic ordering of the transition metal magnetic moments along the c- axis and along the b-axis for cobalt and iron kotoites. The magnetic cell of Ni3B2O6 kotoite corresponds to k = (1/2, 0, 1/2) vector and four time larger than the unit cell. The calculated exchange constants indicate the competition between ferromagnetic and antiferromagnetic interactions. At a critical pressure, Me ions undergo a high-spin to low-spin state crossover. This magnetic moments collapse is analyzed in terms of change in electronic structure under pressure.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N.
Заглавие : Magnetic and electronic properties of M3B2O6 (Me=Mn, Fe, Co, Ni) kotoites: representation analysis and DFT calculations
Коллективы : International Baltic Conference on Magnetism, Балтийский федеральный университет им. И. Канта
Место публикации : V International Baltic Conference on Magnetism. IBCM: Book of abstracts. - 2023. - P.149
Примечания : Cited References: 2. - РНФ № 22-22-20024 ; Красноярский регион. фонд науки
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zinenko V. I.
Заглавие : Calculations of the lattice dynamics and spontaneous polarization for thin ferroelectric films of disordered solid solutions PbB'(1/2) BaEuro(1/2)(3)O(3) (B' = Sc, Ga, In, Lu; BaEuro(3) = Nb, Ta)
Коллективы : Russian Foundation for Basic Research; President of the Russian Federation [NSh-4137.2006.2]
Место публикации : Phys. Solid State. - 2009. - Vol. 51, Is. 9. - P.1894-1900. - ISSN 1063-7834, DOI 10.1134/S1063783409090212
Примечания : Cited References: 13. - This study was supported by the Russian Foundation for Basic Research and the Council on Grants from the President of the Russian Federation for Support of the Leading Scientific Schools of the Russian Federation (grant no. NSh-4137.2006.2).
Аннотация: The lattice dynamics and spontaneous polarization in thin ferroelectric films of disordered solid solutions PbB'(1/2) BaEuro(1/2)(3) O-3 (B' = Sc, Ga, In, Lu; BaEuro(3) = Nb, Ta) are calculated in terms of the generalized Gordon-Kim model. It is found that all the compounds under investigation contain an unstable polar mode, the frequencies of this mode for all the compounds are close in magnitude, and the eigenvectors of the soft polar mode are different in character for different types of surfaces (PbO and aOE (c) B O-2, where aOE (c) B is the average ion in the virtual crystal approximation). The frequency of the soft polar mode, the dynamic Born charges, and the rf permittivity are calculated as functions of the film thickness. It is demonstrated that, as the film thickness increases, all the above quantities tend to corresponding values for the bulk compound. The spontaneous polarization of the monoclinic phase distorted along the eigenvector of the soft mode is calculated as a function of the film thickness and in individual layers of the film for different types of surfaces.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Nemtsev A. V.
Заглавие : Ab initio study of the magnetic, optical and electronic properties of spinel Co3O4 within DFT and GW approaches
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 499. - Ст.166306. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2019.166306. - ISSN 1873-4766 (eISSN)
Примечания : Cited References: 65. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 18-42-243019: «First-principles studies of the polarization, magnetic, electronic, and magnetoelectric properties of functional compounds with a spinel structure containing 3d and 4f ions». The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class ”SRC“ Kurchatovsky Institute” (http://ckp.urcki.ru).
Аннотация: The spinel cobalt oxide Co3O4 is an antiferromagnetic semiconductor containing two non-equivalent Co2+ and Co3+ cobalt ions with different local environments and different magnetic moments. We have performed ab initio study and comparison of the electronic, magnetic and optical properties of Co3O4 within GGA, GGA + U, and G0W0 approximations. GGA correctly predicts Co3O4 to be a semiconductor, but severely underestimates the bandgap. G0W0 approximations increase the bandgap indicating a better description of the cobalt localized d-states. The spectral weights of the bands near Fermi energy are about 0.5. Ab initio calculations confirm that the low-spin state of Co3+ ion arises due to the local environment and the crystal effect field. The investigation of the pressure dependencies of magnetic properties revealed the appearance of Co3+ ion abrupt transition from low-spin state to high-spin state under tensile pressure. This allows manipulating the spin state of Co3+ ions through the pressure or strain.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Nemtsev A. V.
Заглавие : Ab initio comparative study of the magnetic, electronic and optical properties of AB2O4 (A, B= Mn, Fe) spinels
Место публикации : Mater. Chem. Phys. - 2021. - Vol. 259. - Ст.124065. - ISSN 0254-0584 (ISSN), DOI 10.1016/j.matchemphys.2020.124065. - ISSN 1879-3312 (eISSN)
Примечания : Cited References: 32. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions » The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: The comparison of the magnetic, electronic, and optical properties of the spinel transition-metal oxides AB2O4 (A, B = Fe, Mn) and their relationship with the structure and composition were studied within DFT-GGA + U approximation. The spinels were considered both in the normal and inverse structure. We have found that regardless of composition and structure, the studied spinels are ferrimagnetic with antiparallel magnetic moments on A- and B-site cations. Electronic and structural properties of spinels depend on the composition: FeMn2O4 has a tetragonal structure and half-metallic properties; however, in the inverse FeMn2O4, the bandgap opens for the spin-up channel. MnFe2O4 is a cubic insulator with a bandgap of about 1.5 eV, which decreases in the inverse structure. The superexchange constants estimate within the simple indirect coupling model and have values close to the experimental ones. The total magnetization of FeMn2O4 is drop-down to zero under hydrostatic pressure above 60 GPa due to the strong dependence of the magnetic moment of octahedral manganese ion on the pressure. The microscopic mechanisms of the relationship between the structure, composition and properties are studied.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : ZEIN N. E., ZINENKO V. I., FEDOROV A. S.
Заглавие : ABINITIO CALCULATIONS OF PHONON FREQUENCIES AND DIELECTRIC-CONSTANTS IN A(4)B(6) COMPOUNDS
Место публикации : Phys. Lett. A: ELSEVIER SCIENCE BV, 1992. - Vol. 164, Is. 1. - P115-119. - ISSN 0375-9601, DOI 10.1016/0375-9601(92)90916-A
Примечания : Cited References: 20
Предметные рубрики: IV-VI COMPOUNDS
CRYSTAL-STRUCTURE
Аннотация: The transverse and longitudinal optical frequencies at q = 0, the dielectric constant and the effective charges are calculated for the A4B6 type family of the semiconducting compounds GeTe, SnTe and PdTe. The calculations are performed in the framework of the density functional method with the use of the norm-conserving "first-principles" pseudopotentials. The estimated ferroelectric phase transition temperatures and a number of other calculated quantities turned out to be in good agreement with the experimental data. The variations of the electronic structure in the row PbTe-GeTe, which promote the ferroelectric phase transition for GeTe, are discussed.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Zinenko V. I.
Заглавие : First-principles calculations of ferroelectric properties in AA`BB`O6 double perovskites with different types of cation ordering
Место публикации : Phys. status solidi B. - 2013. - Vol. 250, Is. 9. - P.1888-1897. - ISSN 0370-1972, DOI 10.1002/pssb.201349084
Ключевые слова (''Своб.индексиров.''): density functional theory--double perovskites--ferroelectrics--polarization
Аннотация: First-principles calculations of lattice dynamics and polarization properties have been performed for double perovskite ABiBNbO6 (A - alkali metal Na, Rb, and B - trivalent metal Sc, Lu). Three possible types of A- and B-site cation ordering are studied: layer and columnar ordering of A-site cations with rocksalt ordering of B-site cations, and layer ordering of both cations. The ground state of all compounds is polar with a large value of polarization for all types of cation ordering. For some compounds we obtain spontaneous polarization of 0.7-1.0Cm-2 that is twice the BaTiO3 value. For RbBiScNbO6 the lowest-energy state has layer ordering of both A- and B-site cations, which is rare for compounds with double-perovskite structure.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Samardak, Alexander S., Ognev, Alexey, V, Kolesnikov, Alexander G., Stebliy, Maksim E., Samardak, Vadim Yu, Iliushin, Ilia G., Pervishko, Anastasiia A., Yudin, Dmitry, Platunov M. S., Ono, Teruo, Wilhelm, Fabrice, Rogalev, Andrey
Заглавие : XMCD and ab initio study of interface-engineered ultrathin Ru/Co/W/Ru films with perpendicular magnetic anisotropy and strong Dzyaloshinskii-Moriya interaction
Коллективы : Russian Ministry of Science and Higher Education [075-15-2021-607, 0657-2020-0013]; Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-32-60020]; Russian Federation President Scholarship for Young Scientists [SP-1640.2021.5]; Russian Science FoundationRussian Science Foundation (RSF) [21-42-00041]; Russian Ministry of Science and Higher Education
Место публикации : Phys. Chem. Chem. Phys. - 2022. - Vol. 24, Is. 14. - P.8225-8232. - ISSN 1463-9076, DOI 10.1039/d1cp05456b. - ISSN 1463-9084(eISSN)
Примечания : Cited References: 47. - A. V. O., I. G. I. and T. O. thank the Russian Ministry of Science and Higher Education for state support of scientific research conducted under the supervision of leading scientists in Russian institutions of higher education, scientific foundations and state research centers (Project No. 075-15-2021-607) in parts of sample preparation and its magnetic characterization. The micromagnetic simulations performed by M. E. S. were supported by the Russian Ministry of Science and Higher Education under the state task (0657-2020-0013). A. A. P. (ab initio calculations) acknowledges the support from the Russian Foundation for Basic Research (Project No. 19-32-60020) and the Russian Federation President Scholarship for Young Scientists (SP-1640.2021.5). The work of A. S. S. related to the experimental and analytical study of DMI and skyrmion bubbles was supported by the Russian Science Foundation (Project No. 21-42-00041). The authors acknowledge the use of computational resources of the Skoltech supercomputer Zhores47 to obtain the theoretical results presented in this paper. The authors thank ID12 beamline staff for their help during the XMCD experiment and gratefully acknowledge the provision of beamtime (Proposal MA-3661) by the ESRF. The research contribution of M. P. (XMCD anaysis) was partially funded by the Russian Ministry of Science and Higher Education via the budget project of SRF SKIF, Boreskov Institute of Catalysis
Предметные рубрики: TOTAL-ENERGY CALCULATIONS
CIRCULAR-DICHROISM
MOLECULAR-DYNAMICS
Аннотация: Understanding the nature of recently discovered spin–orbital induced phenomena and a definition of a general approach for “ferromagnet/heavy-metal” layered systems to enhance and manipulate spin–orbit coupling, spin–orbit torque, and the Dzyaloshinskii–Moriya interaction (DMI) assisted by atomic-scale interface engineering are essential for developing spintronics and spin-orbitronics. Here, we exploit X-ray magnetic circular dichroism (XMCD) spectroscopy at the L2,3-edges of 5d and 4d non-magnetic heavy metals (W and Ru, respectively) in ultrathin Ru/Co/W/Ru films to determine their induced magnetic moments due to the proximity to the ferromagnetic layer of Co. The deduced orbital and spin magnetic moments agree well with the theoretically predicted values, highlighting the drastic effect of constituting layers on the system's magnetic properties and the strong interfacial DMI in Ru/Co/W/Ru films. As a result, we demonstrate the ability to simultaneously control the strength of magnetic anisotropy and intermixing-enhanced DMI through the interface engineered inversion asymmetry in thin-film chiral ferromagnets, which are a potential host for stable magnetic skyrmions.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sokolov A. Е., Ivanova O. S., Fedorov A. S., Kovaleva E. A., Vysotin M. A., Lin, C-R, Ovchinnikov S. G.
Заглавие : Why the magnetite-gold core-shell nanoparticles are not quite good and how to improve them
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-52-52002]; Ministry of Science and Technology of TaiwanMinistry of Science and Technology, Taiwan [109-2112-M-153-003, 108-2923-M-153-001-MY3]
Место публикации : Phys. Solid State. - 2021. - Vol. 63, Is. 10. - P.1536-1540. - ISSN 1063-7834, DOI 10.1134/S1063783421090365. - ISSN 1090-6460(eISSN)
Примечания : Cited References: 35. - This study was supported by the Russian Foundation for Basic Research, project no. 19-52-52002, and the Ministry of Science and Technology of Taiwan, projects MOST nos. 109-2112-M-153-003 and 108-2923-M-153-001-MY3
Предметные рубрики: IRON-OXIDE NANOPARTICLES
TOTAL-ENERGY CALCULATIONS
STABILITY
DESIGN
Аннотация: The nature of the formation of a chemical bond at the magnetite-gold interface has been studied. The geometric structure and the electronic and magnetic properties of plane layers consisting of magnetite Fe3O4 and gold have been investigated using the DFT-GGA calculation. It has been found that the specific energy and the wetting parameter of the magnetite-gold interface are negative, which leads to the island growth of small Au particles on the Fe3O4 surface. The role of an intermediate thin titanium layer between magnetite and gold has been discussed. The specific energy and wetting parameter of the magnetite-titanium (for thin Ti layers) and magnetite-titanium-gold interfaces are positive. It has been suggested that an intermediate thin titanium layer at the interface between the magnetite nanoparticle surface and the gold layer will make it possible to obtain magnetite nanoparticles with a continuous gold coating.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Varganov S. A., Avramov P. V., Ovchinnikov S. G.
Заглавие : Ab initio calculations of endo- and exohedral C-60 fullerene complexes with Li+ ion and the endohedral C-60 fullerene complex with Li-2 dimer
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2000. - Vol. 42, Is. 2. - P388-392. - ISSN 1063-7834, DOI 10.1134/1.1131218
Примечания : Cited References: 16
Предметные рубрики: ELECTRONIC-STRUCTURE
ENERGIES
C60
Аннотация: The results of ab initio Hartree-Fock calculations of endo- and exohedral C-60 fullerene complexes with the Li+ ion and Li-2 dimer are presented. The coordination of the Li+ ion and the Li-2 dimer in the endohedral complexes and the coordination of Li+ ion in the exohedral complex of C-60 fullerene are determined by the geometry optimization using the 3-21G basis set. In the endohedral Li+C60 complex, the Li+ ion is displaced from the center of the C-60 cage to the centers of carbon hexa- and pentagons by 0.12 nm. In the Li-2 dimer encapsulated inside the C-60 cage, the distance between the lithium atoms is 0.02 nm longer than that in the free molecule. The calculated total and partial one-electron densities of states of C-60 fullerene are in good agreement with the experimental photoelectron and X-ray emission spectra. Analysis of one-electron density of states of the endohedral Li+@C-60 complex indicates an ionic bonding between the Li atoms and the C-60 fullerene. In the Li+C60 and Li+@C-60 complexes, there is a strong electrostatic interaction between the Li+ ion and the fullerene. (C) 2000 MAIK "Nauka/Interperiodica".
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20.

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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