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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Киренский, Леонид Васильевич, Саланская, Любовь Александровна, Саланский, Наум Моисеевич
Заглавие : Об определении "эффективной" локальной анизотропии в поликристаллических пермаллоевых пленках
Место публикации : Физ. металлов и металловед. - 1969. - Т. 28, вып. 6. - С. 1115-1118
Примечания : Библиогр.: 7 назв.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Петров, Михаил Иванович, Balaev D. A., Khrustalev B. P., Aleksandrov K. S.
Заглавие : The effect of heat treatment on the transport properties of the polycrystalline HTSC
Место публикации : Physica C-Superconductivity and its Applications. - 1994. - Vol. 235-240, Is. 5. - P.3043-3044. - ISSN 0921-4534, DOI 10.1016/0921-4534(94)91048-0
Примечания : Cited References: 6
Аннотация: Temperature dependences of transport critical current (Jc) have been studied for polycrystalline HTSC samples of 1-2-3 structure with Y3/4Lu1/4Ba2Cu3O7 composition. The main aim of the investigation was the effect of the boundaries between crystallites on the current-carrying capability of the high-temperature superconductor. The modifications of the boundaries have been achieved by the long time heat treatments up to one week (?150 hours). It has been demonstrated experimentally that the Kulik-Omel'yanchuk theory describes adequately the temperature dependence of Jc of samples with short heat treatment time in "clean" limit. The absolute value of Jc (4.2k) ? 1.4kA/cm2. Long-term heat treated samples have Jc(4.2K) ? 0.1kA/cm2 and the temperature dependence of Jc becomes close to predictions of de Gennes theory. В© 1994.
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3.

Вид документа : Однотомное издание (Препринт)
Шифр издания : В36
Автор(ы) : Petrov M. I., Balaev D. A., Khrustalev B. P., Aleksandrov K. S.
Заглавие : Critical currents of polycrystalline HTSC with 1-2-3 structure undergone the heat treatment : препринт. № 752Ф
Выходные данные : Krasnoyarsk, 1994
Колич.характеристики :13 с
Коллективы : Russian Academy of Sciences, Siberian Branch RAS, Kirensky Institute of Physics
Примечания : Refereces.: 9 назв. :
ГРНТИ : 29.19.29 + 29.19.23 + 29.19.31
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfeld D. M., Ospishchev S. V., Shaikhutdinov K. A., Aleksandrov K. S.
Заглавие : Applicability of the theory based on Andreev reflection to the description of experimental current-voltage characteristics of polycrystalline HTSC plus normal metal composites
Место публикации : Physica C. - 1999. - Vol. 314, Is. 1-2. - P.51-54. - ISSN 0921-4534, DOI 10.1016/S0921-4534(99)00151-3
Примечания : Cited References: 19
Предметные рубрики: WEAK LINKS
JUNCTIONS
FILMS
Ключевые слова (''Своб.индексиров.''): ybacuo + bapbo3 composites--network of weak s-n-s links--current-voltage characteristic
Аннотация: Measurements of current-voltage characteristics (CVC) of Y3/4Lu1/4Ba2,Cu3O7 + BaPbO3 and Y3/4Lu1/4Ba2Cu3O7 +BaPb0.9Sn0.1O3 composites modelling network of superconducting-normal metal-superconducting (S-N-S) junctions in effectively 'clean' and 'dirty' limits, respectively, have been performed. Essential difference of CVCs for these composites is observed in spite of the identical preparation technique and experimental conditions. It is shown that the theory for S-N-S junctions [R. Kummel, U. Gunsenheimer, R. Nicolsky, Phys. Rev. B, 42 (1990) 3932] well describes the experimental CVCs of the composites in both cases. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mamalis A. G., Petrov M. I., Balaev D. A., Shaihutdinov K. A., Gohfeld D. M., Militsyn S. V., Ovchinnikov S. G., Kirko V. I., Vottea I. N.
Заглавие : A DC superconducting fault current limiter using die-pressed YBa2Cu3O7 ceramic
Место публикации : Supercond. Sci. Technol.: IOP PUBLISHING LTD, 2001. - Vol. 14, Is. 6. - P413-416. - ISSN 0953-2048, DOI 10.1088/0953-2048/14/6/316
Примечания : Cited References: 14
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK LINKS
COMPOSITES
Ключевые слова (''Своб.индексиров.''): current voltage characteristics--electric fault currents--high temperature applications--josephson junction devices--polycrystalline materials--fault current limiter devices--superconducting materials
Аннотация: A model of a superconducting fault current limiter on a polycrystalline high-temperature superconductor basis is checked in the dc short circuit regime. Protection of load takes place under the conditions described in this paper. The use of ceramic materials with superconducting-normal metal-superconducting Josephson junction network having an S-type current-voltage characteristic (CVC) is shown to be effective for fault current limiter devices.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Shaikhutdinov K. A., Aleksandrov K. S.
Заглавие : Superconductor-semiconductor-superconductor junction network in bulk polycrystalline composites Y3/4Lu1/4Ba2Cu3O7 + Cu1-xLixO
Место публикации : Superconductor Science and Technology. - 2001. - Vol. 14, Is. 9. - P.798-805. - ISSN 0953-2048, DOI 10.1088/0953-2048/14/9/333
Ключевые слова (''Своб.индексиров.''): critical current density (superconductivity)--josephson junction devices--polycrystalline materials--superconductivity--thermal effects--transport properties--superconductor junction networks--semiconductor junctions
Аннотация: Bulk Y3/4Lu1/4Ba2Cu3O7 + Cu1-xLixO composites with x = 0, 0.003 and 0.06 and varied volume content of Cu1-xLixO have been prepared. Analysis of the transport properties of the composites has shown that they can be represented as a network of superconductor-semiconductor-superconductor (S-Sm-S) weak links. The dependence of the critical current density on the normal resistance for the composites studied shows a behaviour similar to that for single Josephson junctions. The experimental temperature dependences of the critical current are qualitatively described in terms of a theory of S-Sm-S junctions that takes into account the Andreev reflection of carriers from the S-Sm and Sm-S interfaces.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Петров, Михаил Иванович, Balaev D. A., Gokhfel'd D. M., Шайхутдинов, Кирилл Александрович, Aleksandrov K. S.
Заглавие : Temperature evolution of the hysteresis in the current-voltage characteristic of a polycrystalline high-temperature superconductor with 1-2-3 structure
Место публикации : Phys. Solid State: American Institute of Physics, 2002. - Vol. 44, Is. 7. - P.1229-1234. - ISSN 1063-7834, DOI 10.1134/1.1494614
Примечания : Cited References: 38
Предметные рубрики: WEAK LINKS
ANDREEV REFLECTIONS
SIMPLIFIED MODEL
EXCESS CURRENT
SNS JUNCTIONS
SCATTERING
COMPOSITES
TRANSPORT
Аннотация: The temperature evolution of the current-voltage (I-U) characteristic of a contact of the break-junction type with direct conduction is investigated on a polycrystalline HTSC of the Y-Ba-Cu-O system. The experimental I-U characteristics possessing a hysteresis are correctly described in the framework of the Kummel-Nicolsky theory for an S-N-S contact (S stands for a superconductor; N, for a normal metal) in which the Andreev reflection of quasiparticles from the N-S interface is considered. It is shown that the shape of the I-U curve, as well as the existence of a hysteresis, is determined by the ratio of the number of "long" and "short" intergranular boundaries in the polycrystal under investigation. The coincidence of the calculated and experimental I-U curves made it possible to estimate the effective length of "natural" intergranular boundaries in polycrystalline HTSC materials. The estimate is obtained from the experimental temperature dependence of the critical current in the sample under investigation. (C) 2002 MAIK "Nauka/Interperiodica".
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd D. M., Shaikhutdinov K. A.
Заглавие : Andreev reflection in natural grain boundaries of polycrystalline high-T-c superconductor La1.85Sr0.15CuO4
Разночтения заглавия :авие SCOPUS: Andreev reflection in natural grain boundaries of polycrystalline high-Tc superconductor La1.85Sr0.15CuO 4
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 7. - P1219-1222. - ISSN 1063-7834, DOI 10.1134/1.1594233
Примечания : Cited References: 30
Предметные рубрики: CURRENT-VOLTAGE CHARACTERISTICS
WEAK LINKS
CHARGE-TRANSPORT
JUNCTIONS
CONDUCTIVITY
HYSTERESIS
COMPOSITES
SCATTERING
Аннотация: The temperature evolution of the current-voltage characteristic (CVC) of a "break junction" with metal-type conductivity on the polycrystalline La1.85Sr0.15CuO4 high-temperature superconductor is investigated. The CVC exhibits gap peculiarities and hysteresis, which is observed in the region of negative differential resistance. The experimental results are described well in terms of the Kummel-Gunsenheimer-Nicolsky theory for an S-N-S junction (S is a superconductor, N is a normal metal) this theory takes into account multiple Andreev reflection of quasiparticles. It is shown that the shape of the CVC and the existence and the shape of hysteresis are determined by the ratio of "long" and "short" grain boundaries in the polycrystal under investigation. (C) 2003 MAIK "Nauka / Interperiodica".
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Gokhfeld D. M., Balaev D. A., Shaihutdinov K. A., Kummel R.
Заглавие : Andreev reflections and experimental current-voltage characteristics of break junctions of polycrystalline HTSC
Место публикации : Physica C: ELSEVIER SCIENCE BV, 2004. - Vol. 408: 7th International Conference on Materials and Mechanisms of Superconductive and High Temperature Superconductors (MAY 25-30, 2003, Rio de Janeiro, BRAZIL). - P620-622. - ISSN 0921-4534, DOI 10.1016/j.physc.2004.03.085
Примечания : Cited References: 3
Ключевые слова (''Своб.индексиров.''): andreev reflections--break junction--current-voltage characteristics--andreev reflections--break junction--current-voltage characteristics--andreev reflections--break junctions--elastic scattering--lattice defects--negative differential resistance--electric fields--heuristic methods--hysteresis--microcracks--polycrystalline materials--probability density function--quasicrystals--superconducting materials--yttrium barium copper oxides--current voltage characteristics
Аннотация: The temperature evolution of current-voltage characteristics (CVCs) of break junctions made from polycrystalline Y0.75Lu0.25Ba2Cu3O7 and La1.85Sr0.15CuO4 is investigated. The experimental CVCs have hysteretic features that reflect a part of a curve with negative differential resistance. The temperature evolution of the CVCs is discussed within the framework of the Kummel-Gunsenheimer-Nicolsky theory for superconductor/normal-metal/superconductor junctions considering multiple Andreev reflections. It is shown that the shape of the CVCs of break junctions is determined by the ratio of the number of "short" and "long" intergrain normal regions in the polycrystalline HTSC under investigation. (C) 2004 Elsevier B.V. All rights reserved.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shaykhutdinov K. A., Balaev D. A., Gokhfeld D. M., Kuzmin Y. I., Popkov S. I., Petrov M. I.
Заглавие : Study of current-voltage characteristics of Bi-based high-temperature superconductors with fractal cluster structure
Коллективы : International Workshop on Weak Superconductivity
Место публикации : Physica C. - 2006. - Vol. 435, Is. 1-2. - P.19-22. - ISSN 0921-4534, DOI 10.1016/j.physc.2006.01.010
Примечания : Cited References: 18
Предметные рубрики: NORMAL-PHASE
VORTEX MOTION
TRANSPORT
Ключевые слова (''Своб.индексиров.''): superconducting foam--pinning--critical current density--fractal--percolation--cluster--cluster--critical current density--fractal--percolation--pinning--superconducting foam--bismuth--critical current density (superconductivity)--electric currents--electric potential--foams--percolation (solid state)--polycrystalline materials--cluster--fractal--pinning--superconducting foam--superconducting materials
Аннотация: We study the effect of the structure on critical currents and current-voltage characteristics (CVC's) of foamed bismuth-based polycrystalline high-temperature superconductors (HTSC). The fractal cluster structure of superconducting foams has been observed and the fractal dimension of boundaries between superconducting and normal clusters has been determined. Based on the magnetic and transport properties of the foamed polycrystalline superconductors, we have shown that the initial parts of CVC's of the superconducting foams are described well by the model that accounts the magnetic flux trapping in fractal clusters of a normal phase. (c) 2006 Elsevier B.V. All rights reserved.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : Description of hysteretic current-voltage characteristics of superconductor-normal metal-superconductor junctions
Место публикации : Supercond. Sci. Technol.: IOP PUBLISHING LTD, 2007. - Vol. 20, Is. 1. - P62-66. - ISSN 0953-2048, DOI 10.1088/0953-2048/20/1/011
Примечания : Cited References: 24
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTOR
WEAK LINKS
POLYCRYSTALLINE HTSC
ANDREEV REFLECTION
SIMPLIFIED MODEL
COMPOSITES
TRANSPORT
Ключевые слова (''Своб.индексиров.''): computational methods--current voltage characteristics--electric resistance--josephson junction devices--mathematical models--yttrium barium copper oxides--andreev reflection--metal superconductor junctions--metallic josephson junction--weak links--semiconductor junctions
Аннотация: A simplified model for the current-voltage characteristics of weak links is suggested. It is based on an approach considering the multiple Andreev reflection in a metallic Josephson junction. The model allows one to calculate the current-voltage characteristics of superconductor-normal metal-superconductor junctions with different thicknesses of normal layer at different temperatures. A hysteretic peculiarity of the V(I) dependence is described as a result of the negative differential resistance. The current-voltage characteristics of tin microbridges and high- T-c composite YBCO + BaPbO3 were computed.
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12.

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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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sapronova N. V., Volkov N. V., Sablina K. A., Petrakovskii G. A., Bayukov O. A., Vorotynov A. M., Velikanov D. A., Bovina A. F., Vasilyev A. D., Bondarenko G. V.
Заглавие : Synthesis of MnGeO3 polycrystalline and single-crystal samples and comparative analysis of their magnetic properties
Коллективы : Russian Foundation
Место публикации : Phys. Status Solidi B. - 2009. - Vol. 246, Is. 1. - P.206-214. - ISSN 0370-1972, DOI 10.1002/pssb.200844013
Примечания : Cited References: 16. - This study was supported by the Integration project CO No 3.7. The authors also thank the Russian Foundation for Science Support.
Аннотация: MnGeO3 single crystals have been grown by a flux method. The obtained MnGeO3 is orthorhombic; a P-bca space group does not undergo any structural phase transitions in the range from room temperature to 900 degrees C. Magnetic measurements carried out for the first time on the MnGeO3 single crystal have revealed higher values (T-N = 38 K and theta = -100 K) as compared to the data for polycrystalline samples reported in the literature (T-N =10 K and 14 K, theta = -54 K and -46 K). These magnetic parameters for polycrystalline samples synthesized by us are close to the literature data. A Mossbauer spectrum taken at T=300 K for a sample containing 5% (Fe2O3)-O-57 shows that manganese ions, Mn2+, occupy two non-equivalent positions and iron is included ina sublattice as Fe2+ and distributed among two positions substituting Mn2+. In this study, the magnetic characteristics are shown to be sensitive even to minor impurity amounts. The MnGeO3 magnetic structure and one of possible reasons causing the effect of impurities on the MnGeO3 magnetic properties are considered in the framework of a simple indirect coupling model. (C) 2009 WILEY-VCH Verlag GmBH & Co. KGaA, Weinheim
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14.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Shaykhutdinov K.A., Popkov S.I., Semenov S.V., Sablina K.A., Volkov N.V.
Заглавие : Low temperature resistiv?ity of polycrystalline (La0.5Eu0.5)0.7Pb0.3MnO3 in a magnetic field
Коллективы : International Conference on Magnetism
Место публикации : 18th International Conference on Magnetism (ICM-2009). - 2009. - Ст.Mo-A-5.1-03
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Semenov S.V., Shaykhutdinov K.A., Popkov S.I., Balaev A.D., Dubrovskiy A.A., Sablina K.A., Volkov N.V.
Заглавие : Magnetoresistance hysteresis in a polycrystalline (La0.5Eu0.5)0.7Pb0.3MnO3 manganite at low temperatures
Коллективы : International Conference on Magnetism
Место публикации : 18th International Conference on Magnetism (ICM-2009). - 2009. - Ст.Mo-A-5.1-03
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16.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Shaykhutdinov K.A., Popkov S.I., Balaev D.A., Dubrovskiy A.A., Semenov S.V., Bykov A.A., Sapronova N.V., Sablina K.A., Volkov N.V.
Заглавие : Low-temperature hysteresis behavior of resistance and magnetization of polycrystalline (La0.5Eu0.5)0.7Pb0.3MnO3
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Уральское отделение РАН
Место публикации : IV Euro-Asian Symposium "Trends in MAGnetism" Nanospintronics (EASTMAG-2010). School for young scientist "Spintronics": June 28 - Lule 2, 2010"Book of abstracts. - Ekaterinburg, 2010. - P.253
РИНЦ
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17.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Patrin G.S., Polyakova K.P., Patrusheva T.N., Klabukov A.A., Seredkin V.A., Patrin K.G., Polyakov V.V.
Заглавие : Polycrystalline La1-xSrxMnO3 films prepared by extraction pyrolitic method
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Уральское отделение РАН
Место публикации : IV Euro-Asian Symposium "Trends in MAGnetism" Nanospintronics (EASTMAG-2010). School for young scientist "Spintronics": June 28 - Lule 2, 2010"Book of abstracts. - Ekaterinburg, 2010. - P.199
РИНЦ
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Abramova G. M., Pankrats A. I., Petrakovskii G. A., Rasch JCE, Boehm M., Vorotynov A. M., Tugarinov V. I., Szumszak R., Bovina A. F., Vasil'ev V.
Заглавие : Electron spin resonance in CuCrS(2) chrome-copper disulphides synthesized by different methods
Разночтения заглавия :авие SCOPUS: Electron spin resonance in CuCrS 2 chrome-copper disulphides synthesized by different methods
Место публикации : J. Appl. Phys.: AMER INST PHYSICS, 2010. - Vol. 107, Is. 9. - Ст.93914. - ISSN 0021-8979, DOI 10.1063/1.3374679
Примечания : Cited References: 13
Предметные рубрики: COLOSSAL MAGNETORESISTANCE
PHYSICAL-PROPERTIES
TRANSITION
Ключевые слова (''Своб.индексиров.''): chemical vapor transport--electron spin resonance--ferromagnets--g-values--magnetic transitions--polycrystalline--synthesis method--temperature range--astatine--paramagnetism--resonance--single crystals--spin dynamics--crystal impurities
Аннотация: The electron spin resonance (ESR) in CuCrS(2) disulphides is found to be strongly dependent on a synthesis method used. At a temperature of 300 K, a polycrystalline CuCrS(2) sample is paramagnetic with a g-value of 1.95 at 40 K, it undergoes the magnetic transition. In the temperature range 4.2-290 K, a single-crystal sample prepared by a chemical vapor transport method exhibits the ESR features typical of a ferromagnet. It is shown that these features are related to the presence of a small amount of the single-crystal CuCr(2)S(4) impurity in the CuCrS(2) single crystal. (C) 2010 American Institute of Physics. [doi:10.1063/1.3374679]
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Dubrovskiy A. A., Popkov S. I., Shaikhutdinov K. A., Mart'yanov O. N., Petrov M. I.
Заглавие : Nonmonotonic Behavior of Magnetoresistance, R(H) Hysteresis, and Low-Temperature Heat Capacity of the BaPb0.75Bi0.25O3 Superconductor in a Magnetic Field: Possible Manifestations of Phase Separation
Коллективы :
Разночтения заглавия :авие SCOPUS: Nonmonotonic behavior of magnetoresistance, R(H) hysteresis, and low-temperature heat capacity of the BaPb0.75Bi0.25O 3 superconductor in a magnetic field: Possible manifestations of phase separation
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 4. - P584-593. - ISSN 1063-7761, DOI 10.1134/S1063776110040059
Примечания : Cited References: 27. - This study was performed under the program no. 5 of the Russian Academy of Sciences (project no. 7).
Предметные рубрики: ELECTRONIC SPECIFIC-HEAT
BAPB1-XBIXO3 SYSTEM
YBA2CU3O7-DELTA
COMPOSITES
TRANSITION
HTSCS
300-K
Ключевые слова (''Своб.индексиров.''): diamagnetic response--effective field--heat capacities--high-t--hysteretic dependence--josephson--low temperature heat capacities--non-monotonic dependence--nonmonotonic behaviors--polycrystalline--spatially inhomogeneous--transport currents--electric resistance--hysteresis--magnetic field effects--magnetic flux--magnetoelectronics--magnetoresistance--phase separation--semiconductor metal boundaries--specific heat--superconducting magnets--superconducting materials--superconductivity--transport properties--magnetic materials
Аннотация: The transport properties (R(T) and R(H) dependences at various values of the transport current in magnetic fields up to 65 kOe) and low-temperature heat capacity in magnetic fields up to 90 kOe of the BaPb0.75Bi0.25O3 superconductor (T-C approximate to 11.3 K) are investigated with the goal of clarifying the mechanisms determining the nonmonotonic behavior and hysteresis of its magnetoresistance R(H). The type of R(H) hysteretic dependences for BaPb0.75Bi0.25O3 is analogous to that observed in granular high-T-c superconductors (HTSCs); however, unlike classical HTSC systems, the field width of the magnetoresistance hysteresis loop for polycrystalline BaPb0.75Bi0.25O3 depends on the transport current. This means that although the mechanisms responsible for the magnetoresistance hysteresis (the influence of the magnetic flux trapped in super-conducting regions on the effective field in Josephson interlayers) are identical in these objects, the transport current in BaPb0.75Bi0.25O3 may considerably affect the diamagnetic response of the superconductor. A considerable effect of transport current on the field in which the R(H) dependences have a peak and exhibit hysterestic properties is observed. Such a behavior can be adequately interpreted using the model of the spatially inhomogeneous superconductor-insulator state proposed by Gorbatsevich et al. [JETP Lett. 52, 95 (1990)]. The nonmonotonic dependence of quantity C/T (C is the heat capacity) on the magnetic field discovered in the present study also agrees with the conclusions based on this model.
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20.

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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