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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkova E. A., Platunov M. S., Antipin A. M., Alpanova R. R., Dubrovskiy A. A., Pyastolova Yu. V., Podobraznyh A. D., Kosorukov V. L., Koporulina E. V., Maltsev V. V.
Заглавие : Synthesis, structure and magnetic properties of monoclinic lanthanum-chromium borate LaCr3(BO3)4
Колич.характеристики :9 с
Место публикации : J. Alloys Compd. - 2024. - Vol. 994. - Ст.174683. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2024.174683. - ISSN 1873-4669
Примечания : Cited References: 38. - Single crystal X-ray analysis was carried out within the State assignment NRC "Kurchatov institute" (research contribution of A.M.A.). The research contribution of M.S.P. was partially supported by the Ministry of Science and Higher Education of the Russian Federation within the governmental assignment for Synchrotron radiation facility "SKIF", Boreskov Institute of Catalysis (project FWUR-2024–0040)
Аннотация: Single crystals of LaCr3(BO3)4 were synthesized through spontaneous nucleation from a K2Mo3O10 flux melt. The crystal structure was determined using single-crystal X-ray diffraction (XRD) at temperatures of 293 K and 85 K. LaCr-borate crystallizes in the monoclinic C2/c space group with unit cell parameters a = 7.47980(5) Å, b = 9.55180(7) Å, c = 11.48330(8) Å, β= 104.0060(6)°, V = 796.04(1) Å3 (for C1, T = 293 K), and a = 7.47380(5) Å, b = 9.55520(7) Å, c = 11.47100(8) Å, β = 103.9330(6)°, V = 795.08(1) Å3 (for C2, T = 85 K), each with Z = 4. The temperature dependence of the unit cell parameters, including the monoclinic angle (β) and the unit cell volume (V), was investigated over the range of 85–293 K. No structural phase transitions were observed in the low-temperature region down to 85 K. Differential scanning calorimetry (DSC) measurements revealed no high-temperature phase transitions between 50 and 1350°C. Infrared (IR) spectroscopy confirmed the monoclinic structure of LaCr3(BO3)4 crystals, revealing characteristic absorption bands, including the lowest frequency mode associated with the translational vibrations of the La3+ ion.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Basova S. A., Molokeev M. S., Oreshonkov A. S., Zhernakov M. A., Khritokhin N. A., Aleksandrovsky A. S., Krylov A. S., Sal’nikova E. I., Azarapin N. O., Shelpakova N. A., Muller-Buschbaum K., Denisenko Yu. G.
Заглавие : Thermochemistry, structure, and optical properties of a new β-La2(SO4)3 polymorphic modification
Колич.характеристики :14 с
Место публикации : Inorganics. - 2023. - Vol. 11, Is. 11. - Ст.434. - ISSN 23046740 (eISSN), DOI 10.3390/inorganics11110434
Примечания : Cited References: 58. - The work was partly carried out within the framework of the Strategic Academic Leadership Program “Priority-2030” for the Kazan Federal University and the state assignment of the Kirensky Institute of PhysicsWe acknowledge Lisa-Marie Wagner (JLU Giessen) for help with X-ray powder diffractometry, and Svetlana Volkova and Irina Palamarchuk (UTMN) for help with IR- and UV-spectrometry. The use of equipment provided by the Krasnoyarsk Regional Center of Research Equipment of Federal Research Center “Krasnoyarsk Science Center SB RAS” is acknowledged
Аннотация: A new polymorphic modification of lanthanum sulfate was obtained by thermal dehydration of the respective nonahydrate. According to powder X-ray diffraction, it was established that β-La2(SO4)3 crystallized in the C2/c space group of the monoclinic system with the KTh2(PO4)3 structure type (a = 17.6923(9), b = 6.9102(4), c = 8.3990(5) Å, β = 100.321(3)°, and V = 1010.22(9) Å3). Temperature dependency studies of the unit cell parameters indicated almost zero expansion along the a direction in the temperature range of 300–450 K. Presumably, this occurred due to stretching of the [LaO9]n chains along the c direction, which occurred without a significant alteration in the layer thickness over the a direction. A systematic study of the formation and destruction processes of the lanthanum sulfates under heating was carried out. In particular, the decisive impact of the chemical composition and formation energy of compounds on the thermodynamic and kinetic parameters of the processes was established. DFT calculations showed β-La2(SO4)3 to be a dielectric material with a bandgap of more than 6.4 eV. The processing of β-La2(SO4)3 with the Kubelka–Munk function exhibited low values below 6.4 eV, which indicated a fundamental absorption edge above this energy that was consistent with LDA calculations. The Raman and infrared measurements of β-La2(SO4)3 were in accordance with the calculated spectra, indicating that the obtained crystal parameters represented a reliable structure.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ivantsov R. D., Mikhailov M. M., Edelman I. S., Yurkin G. Yu.
Заглавие : Features of magnetic and magneto-optical properties of lanthanum manganite microparticles
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : The Sixth Asian school-conference on physics and technology of nanostructured materials: Proceedings. - VLadivostok, 2022. - Ст.III.o.06. - P.128. - ISBN 987-5-8044-1716-2
Примечания : Cited References: 1
Аннотация: For La1-xSrxMnO3 powders prepared by the solid-phase reaction method using various thermal regimes and x values, the temperature dependences of magnetization, circular magnetic dichroism (MCD), and diffuse reflectance spectra were studied. The powders synthesis at temperatures of 800–900 °C for 2 h leads to the formation of a multiphase state. The higher temperatures and duration of synthesis lead to the formation of two predominant magnetic phases with the Curie temperature (TC) of about 250 and 360 K. Correlation is established between magnetic states of the powder and the shape of the diffuse reflection spectra. The strong red shift of the MCD spectrum for the La1-xSrxMnO3 powder is revealed comparing to the MCD spectra of La1-xSrxMnO3 films available in literature.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ivantsov R. D., Mikhailov M. M., Yurkin G. Yu., Edelman I. S.
Заглавие : Preparation, phase evolution, and magnetic properties of lanthanum manganite perovskite powders synthesized by solid-state reaction
Коллективы : Российская академия наук, Уральское отделение РАН, Институт физики металлов им. М. Н. Михеева Уральского отделения РАН, Уральский федеральный университет им. первого Президента России Б.Н. Ельцина, Российский фонд фундаментальных исследований, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : Euro-asian symposium "Trends in magnetism" (EASTMAG-2019): Book of abstracts/ чл. конс. ком.: S. G. Ovchinnikov, N. V. Volkov [et al.] ; чл. прогр. ком. D. M. Dzebisashvili [et al.]. - 2019. - Vol. 1. - Ст.C.P14. - P.294-295. - ISBN 978-5-9500855-7-4 (Шифр В33/E12-125657784)
Примечания : Cited References: 6. - The reported study was carried out with the financial support of the Russian Foundation for Fundamental Research, the Government of the Krasnoyarsk Territory, the Krasnoyarsk Territory Fund for Support of Scientific and Technical Activity in the framework of scientific Projects No. 18-43-243003 and No. 18-42-243011. The work is supported by the Special Program of the Ministry of Education and Science of the Russian Federation for the Siberian Federal University
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Zobkalo I. A., Dubrovskii A. A., Smirnov O. P., Nikitin S. E., Terent'ev K. Yu., Gavrilov S. V., Shaikhutdinov K. A.
Заглавие : Two-dimensional antiferromagnetic correlations in an La1.4Sr1.6(Mn0.9Co0.1)2O7 single crystal
Место публикации : J. Exp. Theor. Phys.: Maik Nauka-Interperiodica Publishing, 2017. - Vol. 124, Is. 5. - P.786-791. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776117050120
Примечания : Cited References: 20
Ключевые слова (''Своб.индексиров.''): antiferromagnetism--cobalt--cobalt compounds--lanthanum compounds--magnetization--magnetostriction--antiferromagnetic correlations--bi-layer--ferromagnetic orderings--field dependence--lanthanum manganites--single-crystal neutron diffraction--single crystals
Аннотация: The temperature and field dependences of the magnetization, the electrical resistivity, and the magnetostriction of bilayer lanthanum manganite La1.4Sr1.6Mn2O7 single crystals and cobalt-doped La1.4Sr1.6(Mn0.9Cu0.1)2O7 are measured. The magnetostriction of the cobalt-doped compound increases as compared to the initial La1.4Sr1.6Mn2O7 compound, and the magnetization and the magnetoresistance of the former compound change substantially. Powder and single-crystal neutron diffraction patterns are used to detect ferromagnetic ordering in La1.4Sr1.6(Mn0.9Co0.1)2O7 at a temperature below TC ~ 45(2) K, and this ordering coexists with antiferromagnetic correlations, which develop at temperatures below TC ~ 80(5) K. © 2017, Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moshkina E. M., Krylov A. S., Sofronova S. N., Gudim, I. A., Temerov V. L.
Заглавие : Crystal growth and Raman spectroscopy study of Sm1-xLaxFe3(BO3)4 ferroborates
Место публикации : Cryst. Growth Des.: American Chemical Society, 2016. - Vol. 16, Is. 12. - P.6915-6921. - ISSN 15287483 (ISSN), DOI 10.1021/acs.cgd.6b01079
Примечания : Cited References: 17. - This work was supported by the Russian Foundation for Basic Research, Project No. 14-02-00307.
Ключевые слова (''Своб.индексиров.''): crystal lattices--iron compounds--raman spectroscopy--single crystals--crystal nucleation--flux methods--internal structure--magnetic phase transitions--magnon scattering--spectral region--temperature range--wave numbers--lanthanum
Аннотация: Sm1-xLaxFe3(BO3)4 (x = 0, 0.75) single crystals were synthesized using the flux method. The crystal nucleation procedure and flux parameters are reported. Conditions for growing the Sm1-xLaxFe3(BO3)4 (x = 0, 0.75) single crystals are described. The prepared crystals were studied by Raman spectroscopy in the temperature range of T = 10-300 K. The spectral region corresponding to temperatures of T = 10-55 K, which involves the temperatures of the magnetic phase transition TN = 32 K for x = 0 and TN = 31 K for x = 0.75, was thoroughly analyzed. Anomalies related to the magnetic ordering established in both compounds were found. The main changes occur in the low-wavenumber region (up to 100 cm-1), where the mode corresponding to magnon scattering arises. This mode is shown to have the internal structure indicative of the occurrence of unstable vibrations (40-80 cm-1). The results obtained are analyzed by calculating the empirical lattice dynamics in Sm1-xLaxFe3(BO3)4 with x = 0 and x = 1. © 2016 American Chemical Society.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Greben'kova Yu.E., Sokolov A. E., Edel'man I. S., Andreev N. V., Chichkov V. I.
Заглавие : Linear and circular magnetic dichroism in thin films of lanthanum manganite
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : V Euro-Asian simposium "Trend in MAGnetism": Nanomagnetism: abstracts. - Vladivostok: FEFU, 2013. - P.324. - ISBN 978-5-7444-3124-2
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Sablina K. A., Sapronova N. V., Volkov N. V.
Заглавие : Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)(0.7)Pb0.3MnO3
Разночтения заглавия :авие SCOPUS: Low-temperature resistance and magnetoresistance hysteresis in polycrystalline (La0.5Eu0.5)0.7Pb 0.3MnO3
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 109, Is. 5. - Ст.53711. - ISSN 0021-8979, DOI 10.1063/1.3559303
Примечания : Cited References: 20. - This study was partially supported by the Russian Foundation for Basic Research, Project No. 08-02-00259a and the Lavrentyev Competition of the Young Scientists' Projects of the Siberian Branch of the Russian Academy of Sciences, Project No. 12.
Предметные рубрики: RESISTIVITY MINIMUM
MANGANITES
FILMS
Ключевые слова (''Своб.индексиров.''): antiferromagnets--electrical resistances--ferromagnets--field dependence--inter-grain--lanthanum manganites--low temperatures--low-temperature resistance--polycrystalline--temperature dependence--tunnel contacts--antiferromagnetic materials--europium--ferromagnetic materials--ferromagnetism--hysteresis--lead--magnetic field effects--magnetoelectronics--magnetoresistance--magnets--manganese oxide--paramagnetism--superconducting materials--electric resistance
Аннотация: The behavior of temperature dependences of electrical resistance and magnetoresistance of polycrystalline substituted lanthanum manganite (La0.5Eu0.5)(0.7)Pb0.3MnO3 at low temperatures was thoroughly studied. A broad hysteresis was found in the field dependences of electrical resistance in the low-temperature region. Above 40 K, no hysteresis feature was observed. The temperature T = 40 K corresponds to the temperature of minimum electrical resistance and the temperature T-N to the antiferromagnet-paramagnet phase transition of the material of the intergrain boundaries. In this work we propose a model which explains the observed features of the rho(T) and rho(H) curves at temperatures below T-N by the formation of a network of ferromagnet-antiferromagnet-ferromagnet tunnel contacts. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559303]
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Electronic Structure of p-Type La1-xMx2+MnO3 Manganites in the Ferromagnetic and Paramagnetic Phases in the LDA plus GTB Approach
Разночтения заглавия :авие SCOPUS: Electronic structure of p-Type La 1-x M x 2+ MnO 3 manganites in the ferromagnetic and paramagnetic phases in the LDA + GTB approach
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 5. - P860-876. - ISSN 1063-7761, DOI 10.1134/S1063776111030101
Примечания : Cited References: 47. - This study was supported financially by integration project no. 40 of the Ural and Siberian Branches of the Russian Academy of Sciences, the program "Strong Electron Correlations" of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 10-02-00251-a).
Предметные рубрики: DOUBLE-EXCHANGE
COLOSSAL MAGNETORESISTANCE
THIN-FILMS
PHYSICS
LA1-XSRXMNO3
RESISTIVITY
SEPARATION
TRANSPORT
MODEL
Ключевые слова (''Своб.индексиров.''): complex structure--cubic materials--ferromagnetic phase--half metals--jahn teller effect--metal properties--metal types--orbitals--p-type--paramagnetic phase--paramagnetic phasis--quasi particles--spectral intensity--spin projections--strong electron correlations--barium--density functional theory--electron correlations--electron density measurement--electronic properties--electronic structure--fermi level--ferromagnetic materials--ferromagnetism--manganese oxide--manganites--paramagnetic materials--paramagnetism--valence bands--lanthanum
Аннотация: The band structure, spectral intensity, and position of the Fermi level in doped p-type La1-xMx2+ MnO3 manganites (M = Sr, Ca, Ba) is analyzed using the LDA + GBT method for calculating the electronic structure of systems with strong electron correlations, taking into account antiferro-orbital ordering and using the Kugel-Khomskii ideas and real spin S = 2. The results of the ferromagnetic phase reproduce the state of a spin half-metal with 100% spin polarization at T = 0, when the spectrum is of the metal type for a quasiparticle with one spin projection and of the dielectric type for the other. It is found that the valence band becomes approximately three times narrower upon a transition to the paramagnetic phase. For the paramagnetic phase, metal properties are observed because the Fermi level is located in the valence band for any nonzero x. The dielectrization effect at the Curie temperature is possible and must be accompanied by filling of d(x) orbitals upon doping. The effect itself is associated with strong electron correlations, and a complex structure of the top of the valence band is due to the Jahn-Teller effect in cubic materials. DOI: 10.1134/S1063776111030101
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Balaev D. A., Semenov S. V., Popkov S. I., Dubrovskiy A. A., Sapronova N. V., Volkov N. V.
Заглавие : Relaxation of low-temperature magnetoresistance and magnetization of polycrystalline (La0.5Eu0.5)(0.7)Pb0.3MnO3
Разночтения заглавия :авие SCOPUS: Relaxation of low-temperature magnetoresistance and magnetization of polycrystalline (La 0.5Eu 0.5) 0.7Pb 0.3MnO 3
Место публикации : J. Phys. D. - 2011. - Vol. 44, Is. 25. - Ст.255001. - ISSN 0022-3727, DOI 10.1088/0022-3727/44/25/255001
Примечания : Cited References: 34. - This work was partially supported by the Lavrentyev Competition of the Young Scientist's Projects of the Siberian Branch of the Russian Academy of Sciences, Project No 12. The authors are grateful to A D Balaev and V M Sosnin for useful discussions on the results.
Предметные рубрики: INSULATOR-METAL TRANSITION
GRANULAR FILMS
NANOPARTICLES
PR0.7CA0.3MNO3
PERCOLATION
MANGANITES
Ключевые слова (''Своб.индексиров.''): antiferromagnetic boundaries--characteristic value--ferromagnetic domains--ferromagnetic metal--lanthanum manganites--logarithmic law--low temperatures--magneto-resistive effect--polycrystalline--relative orientation--relaxation of magnetization--temperature fluctuation--time evolutions--time interval--tunnel magnetoresistance--antiferromagnetism--electric resistance--europium--ferromagnetic materials--ferromagnetism--grain boundaries--grain size and shape--lanthanum compounds--lead--magnetic domains--magnetic moments--magnetoelectronics--magnetoresistance--manganese oxide--magnetization
Аннотация: Hysteresis and relaxation of magnetoresistance and magnetization of substituted (La0.5Eu0.5)(0.7)Pb0.3MnO3 lanthanum manganite in a low-temperature region ( 40 K) are investigated. It is shown that at these temperature features of the magnetoresistive effect are determined mainly by spin-dependent tunnelling of carriers via insulating grain boundaries. As was demonstrated previously, the grain boundaries may be antiferromagnetically ordered. Therefore, relaxation of magnetization and resistance is determined by the processes of relative orientation of the magnetic moments of ferromagnetic domains neighbouring the antiferromagnetic boundary of ferromagnetic domains under the action of temperature fluctuations. It is shown that relaxation follows the logarithmic law within the time interval t similar to 10(2)-3x10(3) s. A comparison between time evolutions of the magnetic moment and resistance shows that magnetoresistance and magnetization are related as delta R
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Semenov S. V., Popkov S. I., Balaev D. A., Bykov A. A., Dubrovskiy A. A., Petrov M. I., Volkov N. V.
Заглавие : Magnetoresistance of substituted lanthanum manganites La0.7Ca0.3MnO3 upon nonequilibrium overheating of carriers
Разночтения заглавия :авие SCOPUS: Magnetoresistance of substituted lanthanum manganites La 0.7Ca 0.3MnO 3 upon nonequilibrium overheating of carriers
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2011. - Vol. 109, Is. 8. - Ст.83711. - ISSN 0021-8979, DOI 10.1063/1.3573666
Примечания : Cited References: 15. - This study was partially supported by the Russian Foundation for Basic Research, project no. 08-02-00259a, and the Lavrent'ev's Competition of Young Scientists of the Siberian Branch of the RAS, project no. 12.
Ключевые слова (''Своб.индексиров.''): field dependence--lanthanum manganites--low thermal conductivity--manganite materials--negative differential resistivity--non equilibrium--non-linearity--nonequilibrium heating--polycrystalline--positive magnetoresistance--transport currents--electric resistance--electron gas--heating--lanthanum--lanthanum alloys--magnetic fields--magnetoelectronics--magnetoresistance--manganese oxide--manganites--thermal conductivity--current voltage characteristics
Аннотация: Current-voltage characteristics of the polycrystalline substituted lanthanum manganite La0.7Ca0.3MnO3 were experimentally studied at T - 77.4 K in magnetic fields up to 13 kOe. In these characteristics, a portion of negative differential resistivity was observed above a certain threshold value of critical current density j caused, in our opinion, by nonequilibrium heating of the electron gas due to low thermal conductivity of the manganite material. Because of the nonlinearity of the current-voltage characteristics, the field dependences of resistivity rho( H) appear extremely sensitive to the value of a transport current. In this case, the rho( H) dependences reveal both ordinary negative and positive magnetoresistance. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3573666]
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Eremin E. V., Patrin G. S., Kim P. D., Seong-Cho Y., Kim D. -H., Chau N.
Заглавие : Current channel switching in the manganite-based multilayer structure
Место публикации : J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 5. - ISSN 17426588 (ISSN), DOI 10.1088/1742-6596/200/5/052031
Ключевые слова (''Своб.индексиров.''): channel switching--current in planes--magnetic tunnel junction--magnetoresistive--manganese silicide--multilayer structures--optical radiations--potential barriers--lanthanum--magnetic fields--manganese--silicides--transport properties--tunnel junctions--manganese oxide
Аннотация: The transport properties of the structure La0.7Sr 0.3MnO3/depleted manganite layer/MnSi have been studied. The depleted manganite layer serves as a potential barrier between the ferromagnetic conducting La0.7Sr0.3MnO3 and MnSi layers by forming a magnetic tunnel junction. The study in the CIP (current-in-plane) geometry has revealed the effect of current channel switching between the manganite layer and the manganese silicide layer with higher conductivity. The effect is controlled by bias current, magnetic field, and optical radiation. Such switching is responsible for the features of the transport properties and the magnetoresistive and photovoltaic effects in the structure. © 2010 IOP Publishing Ltd.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaikhutdinov K. A., Popkov S. I., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Sablina K. A., Volkov N. V.
Заглавие : Low-temperature resistivity of polycrystalline (La0.5Eu 0.5)0.7Pb0.3MnO3 in a magnetic fields
Место публикации : J. Phys. Conf. Ser. - 2010. - Vol. 200, Is. SECTION 5. - ISSN 17426588 (ISSN) , DOI 10.1088/1742-6596/200/5/052025
Ключевые слова (''Своб.индексиров.''): antiferromagnetic grains--comparative analysis--ferromagnetic grain--low temperatures--polycrystalline--specific heat measurement--spin dependent tunneling--transport and magnetic properties--antiferromagnetism--electric resistance--europium--grain boundaries--grain size and shape--lanthanum compounds--lead--magnetic field effects--magnetic properties--magnetoresistance--manganese oxide--single crystals--thermal variables measurement--lanthanum
Аннотация: The effect of grain boundaries on magnetoresistance (MR) of manganites have been investigated by the comparative analysis of the properties of single-crystal and polycrystalline (La0.5Eu0.5) 0.7Pb0.3MnO3. While MR of the single crystal is maximum near the Curie temperature and vanishes in the low-temperature region, the polycrystalline (La0.5Eu0.5)0.7Pb 0.3MnO3 sample exhibits high MR in the low-temperature region. In order to clarify the origin of the low-temperature MR, the transport and magnetic properties of the polycrystalline (La0.5Eu 0.5)0.7Pb0.3MnO3 in magnetic fields have been supplemented by study of magnetic properties and specific heat measurements. The results obtained could be attributed to spin-dependent tunneling between ferromagnetic grains through insulating antiferromagnetic grain boundaries. © 2010 IOP Publishing Ltd.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Popkov S. I., Balaev D. A., Semenov S. V., Bykov A. A., Dubrovskiy A. A., Sapronova N. V., Volkov N. V.
Заглавие : Non-linear current-voltage characteristics of (La0.5Eu0.5)(0.7)Pb0.3MnO3 single crystals: Possible manifestation of the internal heating of charge carriers
Коллективы :
Разночтения заглавия :авие SCOPUS: Non-linear currentvoltage characteristics of (La0.5Eu 0.5)0.7Pb0.3MnO3 single crystals: Possible manifestation of the internal heating of chargecarriers
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2010. - Vol. 405, Is. 24. - P4961-4965. - ISSN 0921-4526, DOI 10.1016/j.physb.2010.09.043
Примечания : Cited References: 19. - The authors are grateful to A.N. Lavrov for useful discussions on the results. This study was partially supported by the Russian Foundation for Basic Research, Project no. 08-02-00259a and the Lavrent'ev Young Scientists' Competition of the Siberian Branch of the Russian Academy of Sciences. Project no. 12.
Предметные рубрики: INSULATOR-METAL TRANSITION
PR0.7CA0.3MNO3
MANGANITES
Ключевые слова (''Своб.индексиров.''): manganites--negative differential resistance--cvc--cvc--manganites--negative differential resistance--applied electric field--charge ordering--current switching--cvc--dielectric regions--experimental data--internal heating--lanthanum manganites--metal-dielectric transition--negative differential resistances--non equilibrium--non-linear--sample heating--temperature evolution--transport currents--electric fields--electron gas--europium--heating--lanthanum--lead--manganites--negative resistance--phase separation--single crystals--thermal conductivity--manganese oxide
Аннотация: Temperature evolution of the current-voltage characteristics (CVCs) of a single-crystal lanthanum manganite (La0.5Eu0.5)(0.7)Pb0.3MnO3 is investigated in a wide (up to 1 A) range of instrumental currents. Effects of a transport current and an applied electric field on the resistance of the material are studied in view of possible implementation of the charge ordering break in dielectric regions occurring due to phase separation in manganites. A negative differential resistance portion observed in the CVCs suggests the presence of a current switching effect. Below the temperature of the metal-dielectric transition in (La0.5Eu0.5)(0.7)Pb0.3MnO3, the hysteresis is observed in the CVC. The detailed analysis of the internal sample heating on the basis of experimental data on thermal conductivity showed, however, that these CVC features can be explained within the concept of non-equilibrium heating of electron gas. (C) 2010 Elsevier B.V. All rights reserved.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Lee C. G., Kim P. D., Eremin E. V., Patrin G. S.
Заглавие : Optically driven conductivity and magnetoresistance in a manganite-based tunnel structure
Коллективы : Russian Foundation for Basic Research [08-02-00259-a, 08-02-00397-a]; Division of Physical Sciences of the RAS; [2.4.2]
Место публикации : J. Phys. D. - 2009. - Vol. 42, Is. 20. - Ст.205009. - ISSN 0022-3727, DOI 10.1088/0022-3727/42/20/205009
Примечания : Cited References: 13. - This study was supported by the Russian Foundation for Basic Research (Projects Nos 08-02-00259-a and 08-02-00397-a) and the Division of Physical Sciences of the RAS, Programme 'Spin-dependent Effects in Solids and Spintronics' (Project No 2.4.2 of the Siberian Branch of the RAS).
Предметные рубрики: JUNCTIONS
Ключевые слова (''Своб.индексиров.''): conducting layers--current-in-plane geometry--dielectric layer--electron hole pairs--interband absorption--magnetic tunnel junction--magnetic tunnels--multilayer structures--optical radiations--photoinduced change--potential barriers--radiation power density--threshold characters--tunnel structures--electric resistance--lanthanum--light--magnetic field effects--magnetoelectronics--magnetoresistance--manganese compounds--oxide minerals--photovoltaic effects--semiconductor junctions--transport properties--vehicular tunnels--wind tunnels--tunnel junctions
Аннотация: In the multilayer structure, La(0.7)Sr(0.3)MnO(3)/depleted manganite layer/MnSi, the photovoltaic effect has been discovered. The depleted manganite layer in the structure is dielectric and serves as a potential barrier between the ferromagnetic conducting La(0.7)Sr(0.3)MnO(3) and MnSi layers by the formation of a magnetic tunnel junction. The photoinduced changes in the transport properties of the magnetic tunnel structure have been observed in the current-in-plane geometry. The changes are reversible and saturate at radiation power densities over 30 mW cm(-2). The photovoltaic effect has a threshold character: it reveals only at h nu 1.17 eV. Most likely, the effect of optical radiation is related to the formation of electron-hole pairs due to interband absorption of light in the dielectric layer. A photocurrent through the tunnel junctions separating the conducting layers causes a redistribution of the current channels between the conducting layers, which influences the conductivity and the magnetoresistance of the structure.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Ovchinnikov S. G., Korshunov M. M., Eremin I. M., Kazak N. V.
Заглавие : Specific features of spin, charge, and orbital ordering in cobaltites
Коллективы : RFBR [09-02-00171-a, 07-02-00226, 09-02-00127]; Federal Agency of Science and Innovation [MK-4278.2008.2]; Presidium of the Russian Academy of Sciences [5, 7]; Leading Science Schools of the Ministry of Education and Science of the Russian Federation [2.1.1/3199]
Место публикации : Phys. Usp.: Turpion Ltd, 2009. - Vol. 52, Is. 8. - P.789-810. - ISSN 1063-7869, DOI 10.3367/UFNe.0179.200908b.0837
Примечания : Cited References: 278. - This work was financially supported by the RFBR (projects 09-02-00171-a, 07-02-00226, and 09-02-00127), the Federal Agency of Science and Innovation (grant MK-4278.2008.2), and the Presidium of the Russian Academy of Sciences Program No. 5, Quantum Physics of Condensed Media (project No. 7). I.M.E.'s work was supported by the program for Leading Science Schools of the Ministry of Education and Science of the Russian Federation (grant 2.1.1/3199).
Предметные рубрики: PEROVSKITE-TYPE OXIDES
METAL-INSULATOR-TRANSITION
HIGH-TEMPERATURE SUPERCONDUCTIVITY
ONE-DIMENSIONAL CA3CO2O6
ELECTRONIC-STRUCTURE
MAGNETIC-PROPERTIES
TRANSPORT-PROPERTIES
STATE TRANSITION
FUEL-CELLS
CRYSTAL-STRUCTURE
Ключевые слова (''Своб.индексиров.''): cobalt oxides--lanthanides--orbital degrees of freedom--orbital ordering--quasi-one-dimensional--spin state--superconducting compounds--theoretical result--calcium--cobalt--lanthanum--oxide minerals--perovskite--spin dynamics--superconductivity--cobalt compounds
Аннотация: Complex cobalt oxides known as cobaltites are reviewed, including LnCoO(3)-based perovskite-structured rare-earth cobaltites (where Ln is lanthanum or a lanthanide), quasi-two-dimensional and quasi-one-dimensional cobaltites of the types LnCo(2)O(5+delta), La2CoO4, and Ca3Co2O8, and NaxCoO2 center dot yH(2)O superconducting compounds. Key experimental and theoretical results are presented, with emphasis on the interplay between charge, spin, and orbital degrees of freedom. Two problems of specific relevance to cobaltites - the spin state instability of Co3+ ions in LnCoO(3), and the nature of superconductivity in NaxCoO2 center dot yH(2)O - are also given significant attention.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gorev M. V., Bondarev V. S., Flerov I. N., Maglione M., Simon A., Sciau P., Boulos M., Guillemet-Fritsch S.
Заглавие : Thermal expansion, polarization and phase diagrams of Ba1-yBi2y/3Ti1-xZrxO3 and Ba1-yLayTi1-y/4O3 compounds
Коллективы : Russian Foundation for Basic Research [07-02-00069]; Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools [NSh-1011.2008.2]
Разночтения заглавия :авие SCOPUS: Thermal expansion, polarization and phase diagrams of Ba 1-yBi2y/3Ti1-xZrxO3 and Ba1-yLayTi1-y/4O3 compounds
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2009. - Vol. 21, Is. 7. - Ст.75902. - С. P. - ISSN 0953-8984, DOI 10.1088/0953-8984/21/7/075902
Примечания : Cited References: 28. - This work was supported by the Russian Foundation for Basic Research ( project no. 07-02-00069) and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools ( project no. NSh-1011.2008.2).
Предметные рубрики: HEAT-CAPACITY
CERAMICS
BA(TI1-XZRX)O-3
FERROELECTRICS
BEHAVIOR
BATIO3
BATI0.65ZR0.35O3
CONDUCTIVITY
PEROVSKITES
CHEMISTRY
Ключевые слова (''Своб.индексиров.''): barium--dielectric properties--lanthanum--phase diagrams--polarization--thermal stress--zirconium--ceramic compositions--root mean squares--temperature ranges--temperature-dependent measurements--thermal expansion co-efficient--thermal-expansion properties--thermal expansion
Аннотация: The thermal expansion properties of the ceramic compositions Ba1-yLayTi1-y/4O3 (y = 0.0, 0.026, 0.036, 0.054) and Ba1-yBi2y/3Ti1-xZrxO3 (y = 0.10; x = 0.0, 0.04, 0.05, 0.10, 0.15) were determined in the temperature range 120-700 K. We report the temperature- dependent measurements of the strain, thermal expansion coefficient and the magnitude of root mean square polarization. The results obtained are discussed together with the data on the structure and dielectric properties.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Balaev D. A., Shaykhutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Current-voltage characteristics of break junctions of high-T-c superconductors
Разночтения заглавия :авие SCOPUS: Current-voltage characteristics of break junctions of high-Tc superconductors
Место публикации : Physica C. - 2007. - Vol. 467, Is. 1-2. - P.80-84. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.09.001
Примечания : Cited References: 19
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
ANDREEV REFLECTION
POLYCRYSTALLINE HTSC
WEAK LINKS
COMPOSITES
Ключевые слова (''Своб.индексиров.''): network of weak links--andreev reflection--hysteretic peculiarity--andreev reflection--hysteretic peculiarity--network of weak links--lanthanum compounds--mathematical models--polycrystalline materials--superconducting materials--andreev reflection--break junctions--hysteretic peculiarity--network of weak links--current voltage characteristics
Аннотация: The current-voltage (I-V) characteristics of break junctions of polycrystalline La1.85Sr0.15CuO4, Y0.75Lu0.25Ba2Cu3O7-delta, Bi1.8Pb0.3Sr1.9Ca2Cu3Ox and composite YBa2Cu3O7-delta + Ag are investigated. The experimental I-V curves exhibit the specific peculiarities of superconductor/normal-metal/superconductor junctions. The relation between an I-V characteristic of network of weak links and I-V dependencies of typical weak links is suggested to describe the experimental data. The I-V curves of typical weak links are calculated by the Kummel-Gunsenheimer-Nicolsky model considering the multiple Andreev reflections. (c) 2007 Elsevier B.V. All rights reserved.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Orlov Yu. S.
Заглавие : Covalence-induced stabilization of an intermediate-spin state and the magnetic susceptibility of LaCoO3
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 104, Is. 3. - P436-444. - ISSN 1063-7761, DOI 10.1134/S1063776107030090
Примечания : Cited References: 24. - This work was supported by the program of the Division of Physical Sciences of the Russian Academy of Sciences “Strong Electronic Correlations,” the integration project SORAN-URORAN (grant no. 74), and the Krasnoyarsk krai Science Foundation
Предметные рубрики: TRANSITION
Ключевые слова (''Своб.индексиров.''): band structure--electron transitions--ground state--hamiltonians--magnetic susceptibility--magnetic variables measurement--spin dynamics--covalence induced stabilization--diagnoalization--orbital degeneracy--spin states--lanthanum compounds
Аннотация: The energies of terms with spins S = 0, 1, 2 have been found using exact diagonalization of the multielectron Hamlitonian of a multiband pd model for the CoO6 cluster. Co (e(g) orbital)-O hops, which form the covalent sigma bond, are shown to decrease the energy of the state (IS) with an intermediate spin (S = 1) as compared to the energy of the state (LS) with a low spin (S = 0). An analogue of the Tanabe-Sugano diagram that takes into account the covalence of the CoO6 cluster is constructed. The state with S = 1 is shown to be a ground state at certain model parameters. An increase in temperature is established to decrease the crystal field and, thus, favors the transition of the ground state from LS to IS at T = 100 K and the transition of the IS ground state to a state (HS) with a high spin (S = 2) at T = 550 K. The magnetic susceptibility of LaCoO3 is calculated with allowance for the LS, IS, and HS states and for the fact that the HS state exhibits threefold orbital degeneracy of the t(2g) shell, which results in an effective orbital moment L = 1 and the importance of spin-orbit interaction. The behavior of this magnetic susceptibility agrees well with the experimental chi(T) dependence of LaCoO3.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Yakimov L. E.
Заглавие : The role of orbital ordering in the formation of electron structure in undoped LaMnO3 manganites in the regime of strong electron correlations
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 6. - P972-985. - ISSN 1063-7761, DOI 10.1134/S1063776106060112
Примечания : Cited References: 25
Предметные рубрики: COLOSSAL MAGNETORESISTIVE OXIDES
DOUBLE EXCHANGE
BAND
MODEL
Ключевые слова (''Своб.индексиров.''): computational methods--correlation methods--doping (additives)--electrons--ferromagnetic materials--lanthanum compounds--paramagnetic materials--intraatomic electron correlations--mott hubbard correlation gap--orbital ordering--paramagnetic phases--electronic structure
Аннотация: The electron structure of undoped LaMnO3 and slightly doped La1-xSrxMnO3 manganites has been calculated within the framework of a generalized tight binding method with explicit allowance for strong intra-atomic electron correlations. According to the results of these calculations, the ground state in orbitally disordered undoped LaMnO3 ferromagnets would be metallic despite the Mott-Hubbard correlation gap in the spectrum of quasiparticles. Owing to the orbital ordering, the insulating state is stabilized in both antiferromagnetic and paramagnetic phases. In-gap states of a polaron nature with a spectral weight proportional to the dopant concentration have been found near the top of the valence band in La1-xSrxMnO3. As the doping level increases, a metal state appears in the ferromagnetic phase, which has a metallic character for one spin subband and an insulating character for the other subband (representing the so-called half-metallic state).
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