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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Дрокина, Тамара Васильевна, Петраковский, Герман Антонович, Молокеев, Максим Сергеевич, Великанов, Дмитрий Анатольевич, Плетнев, Олег Николаевич, Баюков, Олег Артемьевич
Заглавие : Особенности кристаллической структуры и магнитные свойства соединения DyFeTi2O7
Место публикации : Физ. тверд. тела. - 2013. - Т. 55, Вып. 10. - С. 1922-1927
Аннотация: Представлены результаты исследования особенностей кристаллической структуры и распределения катионов железа по позициям в соединении DyFeTi2O7, проведено сравнение с изоструктурным соединением GdGaTi2O7. Методами мессбауэровской спектроскопии и рентгеновской дифракции подтвержден атомный беспорядок в распределении ионов железа Fe3+ по структурным позициям в DyFeTi2O7. Результаты магнитных измерений в низкотемпературной области показывают излом на температурной зависимости магнитного момента и его зависимость от магнитной предыстории образца. Полученные экспериментальные данные позволяют сделать вывод о реализации состояния спинового стекла с температурой замерзания Tf=6 K в соединении DyFeTi2O7
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokina T. V., Petrakovskii G. A., Molokeev M. S., Velikanov D. A., Pletnev N. O., Bayukov O. A.
Заглавие : Specific features of the crystal structure and magnetic properties of the DyFeTi2O7 compound
Место публикации : Phys. Solid State. - 2013. - Vol. 55, Is. 10. - P.2037-2042. - ISSN 1063-7834, DOI 10.1134/S1063783413100107
Аннотация: Results of studying the specific features of formation of the crystal structure and distribution of iron cations over the sites in the DyFeTi2O7 compound have been presented and the comparison with the GdGaTi2O7 isostructural compound has been performed. The atomic disorder in the distribution of the Fe3+ ions over structural sites in the DyFeTi2O7 compound is confirmed by the Mossbauer spectroscopy and X-ray diffractometry. The results of magnetic measurements in the low-temperature region have revealed an inflection point in the temperature dependence of the magnetic moment and its dependence on the magnetic prehistory of the sample. The obtained experimental data suggest that there is a spin glass state with freezing point Tf = 6 K in the DyFeTi2O7 compound. В© 2013 Pleiades Publishing, Ltd.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Zlotnikov A. O.
Заглавие : Coexistence of superconductivity and antiferromagnetism in heavy-fermion intermetallic compound CeRhIn5
Место публикации : J. Supercond. Nov. Magn. - 2013. - Vol. 26, Is. 9. - P.2885-2886. - ISSN 1557-1939, DOI 10.1007/s10948-013-2222-4
Ключевые слова (''Своб.индексиров.''): coexistence superconductivity antiferromagnetism--heavy-fermion systems--periodic anderson model
Аннотация: An interference of heavy-fermion superconductivity (SC) and antiferromagnetism (AFM) has been studied in the framework of the periodic Anderson model with the superexchange interaction between localized electrons. It has been shown that pressure-induced energy change of the localized states leads to modifying antiferromagnetic and superconducting order parameters. Conditions have been found for the coexistence of SC and AFM in the model. Theoretical results of the pressure effects on the ground state character of the heavy-fermion systems are in good agreement with experimental data for a rare-earth intermetallic compound CeRhIn5. The divergence of the effective electron mass produced by suppressing the long-range antiferromagnetic order has also been analyzed in the same framework. В© 2013 Springer Science+Business Media New York.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakinci Z. D., Gokhfeld D. M., Altin E., Kurt F., Altin S., Demirel S., Aksan M. A., Yakinci M. E.
Заглавие : Jc enhancement and flux pinning of Se substituted YBCO compound
Место публикации : J. Mater. Sci.: Mater. Electron.: Springer, 2013. - Vol. 24. - P.4790–4797. - ISSN 0957-4522, DOI 10.1007/s10854-013-1476-8
Примечания : The work is supported by Project No. 7 of RAS Program ‘"Quantum physics of condensed matter"
Аннотация: Y2/3 Se1/3Ba2Cu3Ox compound was fabricated by using solid state fabrication technique. Optimum heat treatments conditions for Y0.77Se0.33Ba2Cu3Ox were investigated. It was determined that the XRD results of these samples were similar to Y-123 phase with some impurities. Magnetization dependence of applied magnetic fields was measured in the range of 0-9В T at 10-50В K. The symmetric and asymmetric M-H loops were obtained for the samples. Magnetization loops obtained from measurements were successfully described by the extended Valkov-Khrustalev model. The temperature and applied magnetic field dependencies of magnetization of sample were estimated and critical current density of samples was calculated by Bean model and pinning force of samples was calculated by using Lorentz force. It is found from critical current density values that Se additions were acted as a pinning center which increased critical current density. В© 2013 Springer Science+Business Media New York.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Drokina T. V., Velikanov D. A., Bayukov O. A., Molokeev M. S., Kartashev A. V., Shadrina A. L., Mitsuk A. A.
Заглавие : Magnetic state of the GdFeTi2O7 compound
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 9. - P.1813-1816. - ISSN 1063-7834, DOI 10.1134/S1063783412090235
Примечания : Cited References: 11
Предметные рубрики: SPIN-GLASS
GD
SM
Аннотация: The X-ray diffraction, Mossbauer, calorimetric, and magnetic characteristics of zirconolite GdFeTi2O7 have been measured to determine the ground magnetic state. A kink dependent on the magnetic prehistory of the sample has been revealed in the temperature dependence of the magnetic moment at T = 3 K. Mossbauer spectroscopy has confirmed the nonequivalence of the iron ion positions in GdFeTi2O7. The experimental data obtained allow the conclusion on the formation of a spin glass state with the freezing temperature T (f) = 3 K in the GdFeTi2O7 compound.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokina T. V., Petrakovskii G. A., Velikanov D. A., Molokeev M. S.
Заглавие : Specific features of magnetic ordering in the SmFeGe2O7 compound
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2014. - Vol. 56, Is. 6. - P.1131-1136. - ISSN 1063-7834, DOI 10.1134/S1063783414060122. - ISSN 1090-6460
Примечания : Cited References: 10
Предметные рубрики: NEUTRON-DIFFRACTION
PR
FERGE2O7
R=LA
Аннотация: The results of the experimental investigation of the magnetic properties of the SmFeGe2O7 compound have been presented. It has been found that the temperature dependence of the susceptibility exhibits two features that coincide with the anomalies in the temperature dependence of the specific heat and indicate magnetic phase transitions in SmFeGe2O7. The external magnetic field induces a magnetic transition, the critical field of which depends on the temperature.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Voronkov M. G., Zel'bst E. A., Vasil'ev A. D., Molokeev M. S., Kuznetsova G. A.
Заглавие : Oxatrane is a parent compound of a new atrane family: Crystal and molecular structure of triethanolamine N-oxide
Коллективы : Council for Grants of the President of the Russian Federation for Support of Leading Scientific Schools [NSh-3649.2014.3]
Место публикации : Dokl. Chem.: Pleiades Publishing, 2014. - Vol. 458. - P.172-175. - ISSN 0012-5008, DOI 10.1134/S0012500814090031. - ISSN 1608-3113
Примечания : This work was supported by the Council for Grants of the President of the Russian Federation for Support of Leading Scientific Schools (grant no. NSh-3649.2014.3).
Предметные рубрики: TERTIARY-AMINES
DIETHANOLAMINE
SILATRANES
OXIDATION
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8.

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.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Kuklin A. V., Kovaleva E. A., Kholtobina A. S.
Заглавие : Theoretical investigation of the adsorption and diffusion of hydrogen on the surface and in the bulk of the intermetallic compound Mg2Ni
Место публикации : Phys. Solid State: Pleiades Publishing, 2014. - Vol. 56, Is. 10. - P.2035-2042. - ISSN 1063-7834, DOI 10.1134/S1063783414100187. - ISSN 1090-6460
Примечания : Cited References: 30
Предметные рубрики: STORAGE MATERIAL Mg2NiH4
INITIO MOLECULAR-DYNAMICS
AUGMENTED-WAVE METHOD
MINIMUM ENERGY PATHS
ELASTIC BAND METHOD
TEMPERATURE STRUCTURE
SADDLE-POINTS
ALLOYS
TRANSITION
MAGNESIUM
Аннотация: The intermetallic compound Mg2Ni as a potential material for hydrogen storage has been investigated theoretically. The sorption and diffusion of a hydrogen atom in the bulk and on the surface of this material, as well as the step-by-step process of dissociative chemisorption of a H-2 molecule on the surface, have been considered. The dependence of the sorption energy of atomic hydrogen on the structural characteristics of the intermetallic compound Mg2Ni has been analyzed.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Sterkhova I. V., Goryunov Y. V., Atuchin V. V.
Заглавие : New class of bicyclic compounds derived from thiobarbituric acid with representative compound 1,3-diethyl-7-hydroxy-5,5,7-trimethyl-2-thioxo-1,2,3,5,6,7-hexahydro-4H-pyrano[2,3-d]pyrimidin-4-one. Preparation, crystal structure, mass spectrometry and IR spectroscopy
Место публикации : J. Mol. Struct.: Elsevier, 2015. - Vol. 1102. - P.101-107. - ISSN 0022-2860, DOI 10.1016/j.molstruc.2015.08.046
Примечания : Cited References: 40. - The work was carried out within the public task of the Ministry of Education and Science of the Russian Federation for research engineering of the Siberian Federal University in 2015 (Contract 3049). V.V.A. is grateful to the Ministry of Education and Science of the Russian Federation for the financial support of the investigation (Contract 14.607.21.0106). The authors also thank SFU CEJU for the technical support
Предметные рубрики: 1,3-diethyl-2-thiobarbituric acid
Crystal-structure
2-thiobarbituric acid
Barbituric-acid
Hydrogen-bond
Derivatives
Diffraction
Equilibria
Inhibitors
Series
Ключевые слова (''Своб.индексиров.''): bicyclic compounds--thiobarbiturates--heterocycles--x-ray diffraction--ir spectroscopy--theoretical calculations
Аннотация: The colorless crystals of 1,3-diethyl-7-hydroxy-5,5,7-trimethyl-2-thioxo-1,2,3,5,6,7-hexahydro-4H-pyrano[2,3-d]pyrimidin-4-one (1) have been crystallized from the solution containing 1,3-diethyl-2-thiobarbituric acid (HDETBA) and equal volumes of concentrated HCl and acetone A possible stoichiometric reaction mechanism has been suggested. The crystal structure of 1 has been determined by X-ray single crystal analysis. The phase purity of the precipitate has been verified by powder X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic structure, space group P212121, with cell parameters a = 9.7454(4), b = 11.2225(4), c = 13.9171(5) Å, Z = 4, V = 1522.1(1) Å3. The molecules of 1 contain the bicyclic ring constructions new in thiobarbiturates. The molecules of 1 are linked by O-H...O hydrogen bonds to infinite molecule chains. The results of mass spectrometric analysis, theoretical studies and IR spectroscopy confirm the structure of 1. Using the PASS software, the general pharmacological potential of 1 was analyzed.
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Drokina T. V., Petrakovskii G. A., Bartolome J., Arauzo A., Molokeev M. S.
Заглавие : Magnetic properties of LuFeTi2O7 compound
Коллективы : International Workshop on Phase Transitions and Inhomogeneous States in Oxides, "Фазовые переходы и неоднородные состояния в оксидах", международный семинар
Место публикации : Int. Workshop on Phase Transit. and Inhomogeneous States in Oxides: book of abstracts. - Kazan, 2015. - P.77
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Kartashev A. V., Gorev M. V., Bogdanov E. V., Mel'nikova S. V., Molokeev M. S., Pogoreltsev E. I., Laptash N. M.
Заглавие : Thermal, structural, optical, dielectric and barocaloric properties at ferroelastic phase transition in trigonal (NH4)2SnF6: A new look at the old compound
Место публикации : J. Fluor. Chem.: Elsevier, 2016. - Vol. 183. - P.1-9. - ISSN 00221139 (ISSN), DOI 10.1016/j.jfluchem.2015.12.010
Примечания : Cited References: 25. - The reported study was partially supported by RFBR, research project No. 15-02-02009a.
Предметные рубрики: Heat-capacity
Ammonium
(NH4)3TiF7
Pressure
Ключевые слова (''Своб.индексиров.''): fluorides--structural disorder--phase transitions--entropy--barocaloric effect
Аннотация: Structural phase transition P-3m1 → P-1 of the first order and nonferroelectric nature was found in (NH4)2SnF6 at about 110 K in the process of thermal, optical, dielectric and X-ray studies. Order-disorder transformation is accompanied by large changes of entropy (ΔS0 = 16.4 J/mol K) and volume (ΔV0/V ≈ 1%). The structural model associated with three orientations of NH4 tetrahedra in P-3m1 phase and their complete ordering in P-1 phase was suggested with the entropy change (ΔS0 = 18.3 J/mol K) close to the experimental value. A good agreement between baric coefficients measured in a direct way (dT0/dp = -157 K/GPa) and evaluated using entropy and volume changes at phase transition (-170 K/GPa) was found. Barocaloric effects in (NH4)2SnF6 are comparable with those of known solid state refrigerants and are characterised by a low-pressure need for realising their maximum values. © 2015 Elsevier B.V. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zinenko V. I.
Заглавие : The effect of structural ordering on the magnetic, electronic, and optical properties of the LaPbMnSbO6 double perovskite
Коллективы : Russian Foundation for Basic Research [15-02-00340-a]; Russian Federation [NSH-924.2014.2]
Место публикации : J. Alloys Compd.: Elsevier Science, 2016. - Vol. 671. - P.184-191. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2016.02.085. - ISSN 1873-4669(eISSN)
Примечания : Cited References:32. - This work was supported by the Russian Foundation for Basic Research, project no. 15-02-00340-a and the Grant of the President of the Russian Federation for Support of Leading Scientific Schools no. NSH-924.2014.2.
Предметные рубрики: SYSTEMS
NI
CO
Ключевые слова (''Своб.индексиров.''): ab initio calculation--double perovskite--magnetic materials--optical--properties--electronic properties--magnetic properties--layer compound
Аннотация: The interplay between the magnetic, electronic, and optical properties and the cation structural ordering in the LaPbMnSbO6 double perovskite is studied using the Vienna Ab Initio Simulation Package (VASP). The layer and rock-salt cation ordering types are investigated. Both of them are of great importance. The rock-salt ordering of B-site cations is one of the most frequently met cation ordering types in double perovskites; the layer ordering of both cations, which can be considered as a heterostructure, is interesting for fundamental research and experimental synthesis. It was established that the properties of the two investigated structures are strongly different. The compound with the layered structure exhibits the behavior typical of a semimetal with the ferromagnetic configuration of magnetic moments, which is unusual for a double perovskite. The rock-salt structure behaves as an antiferromagnetic insulator. Another surprising feature of the structure with the layer ordering is the coexistence of a polar phase and the metal-type conductivity. The calculated optical characteristics of the two ordered structures are compared with the experimental dates. (C) 2016 Elsevier B.V. All rights reserved.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Lesnikov M. K., Atuchin V. V.
Заглавие : First outer-sphere 1,3-diethyl-2-thiobarbituric compounds [M(H2O)6](1,3-diethyl-2-thiobarbiturate)2·2H2O (M = Co2+, Ni2+): Crystal structure, spectroscopic and thermal properties
Место публикации : Chem. Phys. Lett.: Elsevier, 2016. - Vol. 653. - P.54-59. - ISSN 00092614 (ISSN), DOI 10.1016/j.cplett.2016.04.059
Примечания : Cited References: 50. - The study was carried out within the public task of the Ministry of Education and Science of the Russian Federation for research engineering of the Siberian Federal University in 2015-2016. V.V. A. is grateful to the Ministry of Education and Science of the Russian Federation for the financial support of the investigation. X-ray data were obtained with use the analytical equipment of Krasnoyarsk Center of collective use of SB RAS.
Предметные рубрики: Thiobarbituric acid complexes
Transition-metal-complexes; 2-thiobarbituric acid; hydrogen-bond
2-thiobarbituric acid
Hydrogen-bond
Chemistry
Transformation
Diffraction
Ligand
Series
Copper
Ключевые слова (''Своб.индексиров.''): 1,3-diethyl-2-thiobarbituric acid--nickel(ii)--cobalt(ii)--coordination compound--x-ray diffraction--infrared spectroscopy--thermal analysis
Аннотация: Two new d-element compounds, [Co(H2O)6](Detba)2·2H2O (1) and [Ni(H2O)6](Detba)2·2H2O (2) (HDetba - 1,3-diethyl-2-thiobarbituric acid) were synthesized and characterized by single-crystal and powder X-ray diffraction analysis, TG-DSC and FT-IR. Structural analysis revealed that (1) and (2) are discrete structures, in which M2+ ion (M = Co, Ni) is six-coordinated by water molecules and it forms an octahedron. The outer-sphere Detba- ions and H2O molecules participate in O-H?(O/S) intermolecular hydrogen bonds which form the 2D layer. Thermal decomposition includes the stage of dehydration and the following stage of oxidation of Detba- with a release of CO2, SO2, H2O, NH3 and isocyanate gases. © 2016 Elsevier B.V. All rights reserved.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bykova L. E., Yakovchuk V. Yu., Zhigalov V. S., Volochaev M. N., Matsynin A. A., Tambasov I. A., Seredkin V. A., Patrin G. S., Bondarenko G. N.
Заглавие : Structural and magnetic features of solid-phase transformations in Mn/Bi and Bi/Mn films
Место публикации : JETP Letters. - 2016. - Vol. 103, Is. 4. - P.254-259. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364016040111
Примечания : Cited References: 47. - This work was supported by the Russian Foundation for Basic Research (project nos. 15-02-00948 and 16-03-00069), by the Council of the President of the Russian Federation for Support of Young Scientists and Leading Scientific Schools (project no. SP-317.2015.1), and by the Foundation for Promotion of the Development of Small Scientific and Engineering Enterprises (project nos. 0011727 and 6662GU2015, program Umnik). The electron microscopy studies were performed on the equipment of the Shared Usage Center, Krasnoyarsk Research Center, Siberian Branch, Russian Academy of Sciences.
Предметные рубрики: High-temperature synthesis
Epitaxial thin-films
State synthesis
Martensitic transformations
Vacuum depositions
MnBi filmsd
Bi
System
Anisotropy
Compound
Аннотация: Solid-phase transformations at different annealing temperatures in Mn/Bi (Mn on Bi) and Bi/Mn (Bi on Mn) films have been studied using X-ray diffraction, electron microscopy, and magnetic measurements. It has been shown that the synthesis of the α-MnBi phase in polycrystalline Mn/Bi films begins at a temperature of ~120°C and the Mn and Bi layers react completely at 300°C. The resulting α-MnBi(001) samples have a large perpendicular magnetic anisotropy (Ku ≃ 1.5 × 107 erg/cm3) and a coercive force H HC ~ 3 kOe. In contrast to Mn/Bi, the ferromagnetic α-MnBi phase in Bi/Mn films is not formed even at annealing processes up to 400°C and Mn clusters are formed in a Bi melt. This asymmetry in phase transformations occurs because chemosorbed oxygen existing on the surface of the Mn film in Bi/Mn films suppresses a solid-phase reaction between Mn and Bi. The analysis of the results obtained implies the existence of new low-temperature (~120°C) structural transformation in the Mn–Bi system. © 2016, Pleiades Publishing, Inc.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokina T. V., Petrakovskii G. A., Keller L., Schefer J., Balaev A. D., Kartashev A. V., Ivanov D. A.
Заглавие : Modulated magnetic structure in quasi-one-dimensional clinopyroxene NaFeGe2O6
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 1. - P121-126. - ISSN 1063-7761, DOI 10.1134/S1063776110061093
Примечания : Cited References: 18
Ключевые слова (''Своб.индексиров.''): antiferromagnetics--clinopyroxenes--field dependence--helical modulation--incommensurate magnetic structures--magnetic phase transitions--monoclinic compound--order-disorder--orientation phase transitions--quasi-one-dimensional--temperature behavior--temperature dependence--wave vector--antiferromagnetism--magnetic devices--magnetic structure--phase transitions--crystallography
Аннотация: The magnetic structure of the NaFeGe2O6 monoclinic compound has been experimentally investigated using the elastic scattering of neutrons. At a temperature of 1.6 K, an incommensurate magnetic structure has been observed in the form of an antiferromagnetic helix formed by a pairs of the spins of the Fe3+ ions with helical modulation in the ac plane of the crystal lattice. The wave vector of the magnetic structure has been determined and its temperature behavior has been studied. The analysis of the temperature dependences of the specific heat and susceptibility, as well as the isotherms of the field dependence of the magnetization, has revealed the existence of not only the order-disorder magnetic phase transition at the point T (N) = 13 K, but also an additional magnetic phase transition at the point T (c) = 11.5 K, which is assumingly an orientation phase transition.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Klauss H. H., Luetkens H., Klingeler R., Hess C., Litterst F. J., Kraken M., Korshunov M. M., Eremin I., Drechsler S. L., Khasanov R., Amato A., Hamann-Borrero J. E., Leps N., Kondrat A., Behr G., Werner J., Buchner B.
Заглавие : Commensurate spin density wave in LaFeAsO: A local probe study
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2008. - Vol. 101, Is. 7. - Ст.77005. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.101.077005
Примечания : Cited References: 28
Предметные рубрики: LAYERED QUATERNARY COMPOUND
SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): arsenic compounds--chlorine compounds--ferromagnetism--magnetic materials--magnetic properties--magnetization--magnets--molybdenum--phase transitions--spin density waves--commensurate spin density wave--external fields--magnetic orders--muon spin relaxations--order parameter--ordered moments--probe measurements--ssbauer spectroscopy--structural phase transition--sublattice magnetizations--temperature dependences--spin dynamics
Аннотация: We present a detailed study on the magnetic order in the undoped mother compound LaFeAsO of the recently discovered Fe-based superconductor LaFeAsO(1-x)F(x). In particular, we present local probe measurements of the magnetic properties of LaFeAsO by means of (57)Fe Mossbauer spectroscopy and muon-spin relaxation in zero external field along with magnetization and resistivity studies. These experiments prove a commensurate static magnetic order with a strongly reduced ordered moment of 0.25(5)mu(B) at the iron site below T(N)=138 K, well separated from a structural phase transition at T(S)=156 K. The temperature dependence of the sublattice magnetization is determined and compared to theory. Using a four-band spin density wave model both, the size of the order parameter and the quick saturation below T(N) are reproduced.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrakovskii G. A., Bezmaternykh L. N., Bayukov O. A., Popov M. A., Schefer J., Neidermayer C., Aleshkevich P., Szymczak R.
Заглавие : Magnetic structure and magnetic excitations in the two-dimensional spin system of the Cu3B2O6 compound
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 7. - P1315-1320. - ISSN 1063-7834, DOI 10.1134/S1063783407070207
Примечания : Cited References: 21
Предметные рубрики: LONG-RANGE ORDER
HEISENBERG-MODEL
GROUND-STATE
GAP
ANTIFERROMAGNET
SRCU2(BO3)(2)
CUGEO3
CHAINS
CAV4O9
Аннотация: This paper reports on the results of measurements of the magnetic susceptibility, heat capacity, neutron scattering, muon spin relaxation, and electron paramagnetic resonance in Cu3B2O6 for the study of the ground state of the spin system of this compound. The results obtained suggest that, at a temperature of 10 K, the spin subsystem of the crystal, which consists of single spins and clusters of pairs and fours of spins interacting with one another, undergoes a transition to a state representing a superposition of the singlet (for clusters) and magnetically ordered (for single spins) states.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivchenko E. L., Voronov M. M., Erementchouk M. V., Deych L. I., Lisyansky A. A.
Заглавие : Multiple-quantum-well-based photonic crystals with simple and compound elementary supercells
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2004. - Vol. 70, Is. 19. - Ст.195106. - ISSN 1098-0121, DOI 10.1103/PhysRevB.70.195106
Примечания : Cited References: 33
Предметные рубрики: EXCITON POLARITONS
DIELECTRIC MEDIUM
OPTICAL LATTICES
BRAGG STRUCTURES
BAND-STRUCTURES
PERIODIC-BRAGG
REFLECTION
ABSORPTION
SPECTRA
ARRAYS
Ключевые слова (''Своб.индексиров.''): article--crystal--crystal structure--elementary particle--light scattering--mathematical analysis
Аннотация: Exciton polaritons in one-dimensional photonic crystals based on multiple quantum well structures are investigated. The effects due to interplay between resonant interaction of light with quantum well excitons, and light scattering from well-barrier interface, are elucidated. Polariton dispersion equations and reflection spectra in structures with two wells in an elementary supercell of the periodic structure are studied. Several examples of different compound elementary supercells are considered. Special attention is paid to structures with the period or the distance between quantum wells satisfying the resonance Bragg condition. Such structures are characterized by a presence of a larger-than-usual polariton stop band. It is shown that in structures with a complex elementary supercell, the width of such a stop band can be significantly enhanced in comparison to that in simple structures.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Flerov I. N., Bondarev V. S., Sciau P., Lehmann A. G.
Заглавие : Heat capacity of the PbFe1/2Ta1/2O3 perovskite-like compound
Разночтения заглавия :авие SCOPUS: Heat Capacity of the PbFe1/2Ta1/2O3 Perovskite-Like Compound
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 3. - P521-525. - ISSN 1063-7834, DOI 10.1134/1.1687872
Примечания : Cited References: 26
Предметные рубрики: SINGLE-CRYSTALS
PBFE0.5TA0.5O3
FERROELECTRICS
DIFFRACTION
NIOBATE
GROWTH
Аннотация: The heat capacity C-p(T) of the complex perovskite PbFe1/2Ta1/2O3 has been studied using adiabatic calorimetry in the temperature range 150-370 K. Three diffuse anomalies in C-p(T) are found to exist at temperatures T-d approximate to 350 K, T-m approximate to 250-300 K, and T-c approximate to 205 K. The anomalous and the lattice contribution to the heat capacity are separated, and the change in the entropy is determined. The results of the study are discussed jointly with the data on the structure and physical properties of the compound. (C) 2004 MAIK "Nauka / Interperiodica".
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