Библиотека института физики им. Л.В. Киренского СО РАН

Главная

Базы данных

Труды сотрудников ИФ СО РАН - результаты поиска

Вид поиска

Каталог книг и брошюр библиотеки ИФ СО РАН

Каталог журналов библиотеки ИФ СО РАН

Труды сотрудников ИФ СО РАН

Область поиска

в найденном

Формат представления найденных документов:
полный	информационный	краткий

Отсортировать найденные документы по:
автору	заглавию	году издания	типу документа

Поисковый запрос: (<.>S=NMR<.>)

Общее количество найденных документов : 11
Показаны документы с 1 по 10

1-10 11-11

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I. P., Sukhovsky A. A., Ivanov Y. N., Raevsky I. P.
Заглавие : Local structure of disordered PbSc1/2Nb1/2O3 in the region of the diffuse tetragonal phase-rhombohedral phase transition
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 2. - P.316-323. - ISSN 1063-7834, DOI 10.1134/S1063783412020047
Примечания : Cited References: 16. - This study was supported by 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-4645.2010.2).
Предметные рубрики: Neutron-diffraction
Order
BaTiO3
PbNiO3
NMR
Аннотация: The local structure of the ferroelectric-relaxor PbSc1/2Nb1/2O3 in the temperature range from 550 to 220 K has been investigated using 45Sc nuclear magnetic resonance. It has been found that, in the paraelectric phase at temperatures below 550 K, the crystal consists of regions of an ordered elpasolite structure and inclusions of the disordered tetragonal perovskite phase with displacements along directions of the [001] type. The relative weight of the tetragonal structure in the region of the paraelectric phase is approximately equal to 0.28. Below the temperature of the phase transition from the disordered modification to the polar phase, the relative weight of the tetragonal phase decreases with decreasing temperature. The tetragonal structure is replaced by the trigonal polar structure. In a wide temperature range (∼50 K), there exists a heterophase structure that is characteristic of relaxors. Note that the correlation length of displacements in the tetragonal phase should be very small to explain the absence of indications of the existence of this phase in the diffraction data.
Смотреть статью,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyanchuk I. O., Bushinsky M. V., Sikolenko V., Efimov V., Volkov N. V., Tobbens D. M., Ritter C., Raveau B.
Заглавие : Ferromagnetism in single-valent manganites
Место публикации : J. Alloys Compd.: Elsevier Science, 2015. - Vol. 619. - P.719-725. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2014.08.236. - ISSN 1873-4669
Примечания : Cited References: 46. - The authors would like to thank J.B. Goodenough for the fruitful discussion. This work has been supported by Belarusian Republican Foundation for Fundamental Research (Grant F14R-040).
Предметные рубрики: PHASE-SEPARATION
DOPED MANGANITES
DOUBLE EXCHANGE
DIFFRACTION
OXIDES
NMR
Ключевые слова (''Своб.индексиров.''): magnetically ordered materials--solid state reactions--exchange and superexchange--magnetic measurements--neutron diffraction
Аннотация: Structural and magnetization measurements have been performed on the La0.7Sr0.3Mn0.85 Nb 0.15 - x 5 + Mg x 2 + O3 stoichiometric compounds. With rise of the Mg2+ content the formal oxidation state manganese increases from +3 ( x = 0 ) up to +3.55 ( x = 0.15 ) . The compositions with 0 ⩽ x ≤ 0.08 undergo a structural transition from rhombohedral to orthorhombic symmetry below room temperature whereas x = 0.1 and x = 0.15 compounds are rhombohedral down to 2 K. The structural parameters evidence that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The Mg-free compound is ferromagnetic with the Curie point of around 150 K and a magnetic moment of 3.1 μ B /Mn. The substitution of Nb5+ with Mg2+ leads to a gradual weakening of the ferromagnetic component while in the x = 0.15 compound A-type antiferromagnetic short-range order is stabilized in spite of macroscopic R 3 ¯ c symmetry. All the compositions show insulating behavior. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder induced by Nb5+ and Mg2+ ions leads to suppression of ferromagnetism.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Structural and thermodynamic consequencies of the interaction of conformational degrees of freedom of azomethines in the nematic phase
Место публикации : J. Struct. Chem.: Springer, 2014. - Vol. 55, Is. 4. - P.605-611. - ISSN 0022-4766, DOI 10.1134/S0022476614040039. - ISSN 1573-8779
Примечания : Cited References: 21
Предметные рубрики: CONJUGATED POLY(AZOMETHINE)S
TERMINAL SUBSTITUENTS
ELECTRONIC-STRUCTURES
FLUORINATED ANALOGS
INTERNAL-ROTATION
MOLECULES
COMPOUND
ANGLES
STATE
NMR
Ключевые слова (''Своб.индексиров.''): azomethines--benzylideneaniline--conformation--steric effects of substituents--nematic-isotropic liquid transition--conformational polymorphism
Аннотация: The interaction of the conformational degrees of freedom of azomethines in the nematic phase, which is induced by electronic donor-acceptor properties of the terminal substituents of the benzylideneaniline core is studied. These degrees of freedom related to the rotation angles phi (k) around the bonds between the substituent and the aniline ring (phi(1)) and also between the CH=N bridge and the aniline ring (omega(2)) are characterized by the parameters Q (k) = aOE (c) cos(2)phi (k) . It is found that the interaction of these degrees of freedom is manifested in the linear dependence Q (2)(Q (1)). Within the phenomenological theory the effect of this interaction on changes delta (k) in the Q (k) values during the nematic liquid crystal-isotropic liquid phase transition is revealed along with the temperature T (NI) and character of this transition. The derivation of previously established empirical dependences T (NI)(Q (k) ) is presented in the presence of direct and indirect steric effects of side substituents affecting the Q (k) values. A diverse combination of delta (k) signs in the nematic phase, which is a prerequisite for the conformational polymorphism of the nematic phases of azomethines, is shown.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Troyanchuk I. O., Bushinsky M. V., Volkov N. V., Sikolenko V., Efimova E. A., Ritter C.
Заглавие : Role of superexchange interactions in the ferromagnetism of manganites
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 120, Is. 1. - P.97-102. - ISSN 1063, DOI 10.1134/S1063776115010173. - ISSN 10906509(eISSN)
Примечания : Cited References:25. - This work was supported by the Belarussian Foundation for Basic Research, project no. F12SO-026.
Предметные рубрики: PHASE
NMR
Аннотация: Compound La0.7Sr0.3Mn0.85Nb0.15O3, in which manganese ions are in an oxidation state close to 3+, are studied by neutron diffraction and magnetic measurements. This compound is shown to be a ferromagnet with T C = 145 K and a magnetic moment of 3.1 μB/Mn at T = 10 K. No signs of cooperative orbital ordering are detected. When Mg2+ ions substitute for some Nb5+ ions, Mn4+ ions appear but ferromagnetism is not enhanced. An increase in the structural distortions leads to a decrease in the ferromagnetic component. The ferromagnetic state is assumed to be caused by substantial hybridization of the e g orbitals of manganese and oxygen, which increases the positive part of the superexchange interactions.
Смотреть статью,
Scopus,
WOS,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Makarov I. A., Shneyder E. I.
Заглавие : Effect of interlayer tunneling on the electronic structure of bilayer cuprates and quantum phase transitions in carrier concentration and high magnetic field
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 2. - P288-302. - ISSN 1063-7761, DOI 10.1134/S106377611005119X
Примечания : Cited References: 64. - This study was supported financially by the program "Quantum Physics of Condensed Media" of the Presidium of the Russian Academy of Sciences (project no. 5.7), the integration projects of the Siberian Branch and the Ural Division of the Russian Academy of Sciences (project no. 40), the Russian Foundation for Basic Research (project no. 09-02-00127), the President of the Russian Federation (grant no. MK-1683.2010.2), and the Federal Target Program P891.
Предметные рубрики: T-J MODEL
HIGH-TEMPERATURE SUPERCONDUCTORS
DIMENSIONAL HUBBARD-MODEL
FERMI-SURFACE
COPPER OXIDES
GROUND-STATE
CUO2 PLANES
SPECTRUM
BAND
NMR
Ключевые слова (''Своб.индексиров.''): antibonding--bi-layer--bilayer cuprates--complex sequences--cuprates--doping levels--external magnetic field--field magnitude--hartree-fock approximations--high magnetic fields--lifshitz transition--main effect--orbitals--perturbation theory--quantum phase transitions--quantum transitions--single-layer structure--theoretical study--unit cells--carrier concentration--copper compounds--density functional theory--electronic properties--electronic structure--hartree approximation--magnetic fields--perturbation techniques--phase transitions--surface structure--quantum theory
Аннотация: We present a theoretical study of the electronic structure of bilayer HTSC cuprates and its evolution under doping and in a high magnetic field. Analysis is based on the t-t'-taEuro(3)-J* model in the generalized Hartree-Fock approximation. Possibility of tunneling between CuO2 layers is taken into account in the form of a nonzero integral of hopping between the orbitals of adjacent planes and is included in the scheme of the cluster form of perturbation theory. The main effect of the coupling between two CuO2 layers in a unit cell is the bilayer splitting manifested in the presence of antibonding and bonding bands formed by a combination of identical bands of the layers themselves. A change in the doping level induces reconstruction of the band structure and the Fermi surface, which gives rise to a number of quantum phase transitions. A high external magnetic field leads to a fundamentally different form of electronic structure. Quantum phase transitions in the field are observed not only under doping, but also upon a variation of the field magnitude. Because of tunneling between the layers, quantum transitions are also split; as a result, a more complex sequence of the Lifshitz transitions than in single-layer structures is observed.
WOS,
Scopus,
РИНЦ,
Смотреть статью,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Drokin N. A., Kumakhov M. A., Shabanov V. F.
Заглавие : Dielectric properties of liquid crystals in polycapillary matrices
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 6. - P1315-1322. - ISSN 1063-7834, DOI 10.1134/S1063783410060314
Примечания : Cited References: 24. - This study was supported by the Council on Grants from the President of the Russian Federation (grant no. 3818.2008.3) and the Siberian Branch of the Russian Academy of Sciences (Integration Project no. 5) and performed within the framework of the State Contract (no. 02.740.11.0220).
Предметные рубрики: MOLECULAR-SIEVES
SILICA AEROGEL
POROUS-GLASS
MEMBRANES
NMR
8CB
Аннотация: This paper reports on the results of investigations into the dielectric properties of liquid crystals embedded in polycapillary matrices and describes a technique for their measurement. It has been revealed that the chemical structure of the rigid core and the length of mobile alkyl groups of liquid-crystal molecules of the alkylcyanobiphenyl group substantially affect the equilibrium configuration of the liquid-crystal director in capillaries. The reorientation of liquid-crystal molecules embedded in capillaries in the nematic phase under the influence of an external magnetic field has been investigated.
WOS,
Scopus,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I.
Заглавие : Dynamical magnetic susceptibility in the lamellar cobaltate superconductor NaxCoO2 center dot yH(2)O
Разночтения заглавия :авие SCOPUS: Dynamical magnetic susceptibility in the lamellar cobaltate superconductor Nax Co O2 y H2 O
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2008. - Vol. 77, Is. 6. - Ст.64510. - ISSN 1098-0121, DOI 10.1103/PhysRevB.77.064510
Примечания : Cited References: 49
Предметные рубрики: UNCONVENTIONAL SUPERCONDUCTIVITY
NMR
Аннотация: We systematically analyze the influence of the superconducting gap symmetry and the electronic structure on the dynamical spin susceptibility in superconducting NaxCoO2 center dot yH(2)O within three different models: The single a(1g)-band model with nearest-neighbor hoppings, the realistic three-band t(2g) model with, and without e(g)' pockets present at the Fermi surface. We show that the magnetic response in the normal state is dominated by the incommensurate antiferromagnetic spin density wave fluctuations at large momenta in agreement with experimental temperature dependence of the spin-lattice relaxation rate. Also, we demonstrate that the presence or the absence of the e(g)' pockets at the Fermi surface does not significantly affect this conclusion. In the superconducting state our results for d(x)(2)-y(2)- or d(xy)-wave symmetries of the superconducting order parameter are consistent with experimental data and exclude nodeless d(x)(2)-y(2)+id(xy)-wave symmetry. We further point out that the spin-resonance peak proposed earlier is improbable for the realistic band structure of NaxCoO2 center dot yH(2)O. Moreover, even if present the resonance peak is confined to the antiferromagnetic wave vector and disappears away from it.
WOS,
Scopus,
Читать в сети ИФ
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zeer E. P., Falaleev O. V., Ivanov Y. N., Petrakovskaya E. A.
Заглавие : Study of molecular mobility in ABF6-center-dot-6H2O crystal family
Место публикации : Fiz. Tverd. Tela. - 1994. - Vol. 36, Is. 8. - P.2210-2220. - ISSN 0367-3294
Примечания : Cited References: 21
Предметные рубрики: PHASE-TRANSITIONS
NMR
SYSTEM
WOS
Найти похожие

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I. P., Elizarev Y. G., Moskvich Yu. N., Kabanov I. S., Shuvalov L. A.
Заглавие : On the sequence of phase-transitions in monoclinic rubidium dihydrophosphate
Место публикации : Fiz. Tverd. Tela. - 1991. - Vol. 33, Is. 10. - P.2938-2944. - ISSN 0367-3294
Примечания : Cited References: 9
Предметные рубрики: RBD2PO4
NMR
WOS
Найти похожие

10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : Spin-array relaxation of the nuclear magnetic system of solid states with multi-spin interactions generated by modulated intense radiofrequent fields
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1996. - Vol. 110, Is. 2. - P635-660. - ISSN 0044-4510
Примечания : Cited References: 24
Предметные рубрики: NMR
WOS
Найти похожие