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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Kirko V. I., Mamalis A. G., Petrov M. I., Ivanov V. V., Balaev D. A., Gokhfel'd D. M., Kharlamova S. A., Militsyn S. V., Shaikhutdinov K. A.
Заглавие : A new concept for a current switch based on a high-temperature superconductor
Место публикации : Tech. Phys.: AMER INST PHYSICS, 2001. - Vol. 46, Is. 10. - P1299-1302. - ISSN 1063-7842, DOI 10.1134/1.1412067
Примечания : Cited References: 14
Предметные рубрики: CURRENT LIMITER
Аннотация: A new concept for a device for protecting an alternating-current network is offered. It is based on a combination of a superconducting limiter of a short-circuit current and a circuit breaker. A high-temperature superconductor in the form of a pile of plane rings is used as the active element of the limiter. The test results of a model of such a limiter are obtained in the steady-state short-circuit regime. The characteristics of composite silverless materials used for design of the breaker are given. (C) 2001 MAIK "Nauka/Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Altin S., Gokhfeld D. M.
Заглавие : Magnetization loops and pinning force of Bi-2212 single-crystal whiskers
Место публикации : Physica C. - 2011. - Vol. 471, Is. 7-8. - P.217-221. - ISSN 0921-4534, DOI 10.1016/j.physc.2011.01.006
Примечания : Cited References: 40. - The work is supported by Project No. 7 of RAS Program "Quantum physics of condensed matter", Grant No. 13 of Lavrentyev competition of young researchers of SB RAS and Scientific and Technical Research Council of Turkey (TUBITAK) under Contract No. TUBITAK-109T747.
Предметные рубрики: T-C SUPERCONDUCTORS
HIGH-TEMPERATURE SUPERCONDUCTORS
JOSEPHSON VORTICES
GROWTH
BI2SR2CACU2O8+DELTA
DENSITY
STATE
FIELD
MELT
Ключевые слова (''Своб.индексиров.''): bi-2212--whisker--magnetization loop--pinning force--extended critical state model--bi-2212--extended critical state model--magnetization loop--pinning force--whisker--bi-2212--extended critical state model--magnetization loop--pinning force--whisker--flux pinning--magnetic fields--magnetization--critical current density (superconductivity)
Аннотация: Dependence of magnetization on applied magnetic field for single-crystal Bi-2212 whiskers was measured at different temperatures. Symmetric and asymmetric magnetization loops were successfully described by the extended critical state model (the extended Valkov-Khrustalev model). Pinning force of whiskers was investigated. (C) 2011 Elsevier B.V. All rights reserved.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Altin S., Gokhfeld D. M.
Заглавие : Transformation of hysteresis loops of a superconductor with magnetic inclusions
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : V Euro-Asian simposium "Trend in MAGnetism": Nanomagnetism: abstracts. - Vladivostok: FEFU, 2013. - P.258. - ISBN 978-5-7444-3124-2
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zeng, Xian Lin, Karwoth, Thomas, Koblischka,, Michael R., Hartmann, Uwe, Gokhfeld D. M., Chang, Crosby, Hauet, Thomas
Заглавие : Analysis of magnetization loops of electrospun nonwoven superconducting fabrics
Место публикации : Phys. Rev. Materials: American Physical Society, 2017. - Vol. 1, No. 4. - Ст.044802. - ISSN 2475-9953, DOI 10.1103/PhysRevMaterials.1.044802
Примечания : Cited References: 55. - We thank Prof. V. Presser (INM Saarbrücken and Saarland University) for the opportunity to use the electrospinning apparatus, and J. Schmauch (Saarland University, Prof. Birringer’s group) for technical assistance. The collaboration UdS-Nancy was supported by the EU-INTERREG IVa, project “Greater Region Magnetism Network (GRMN)”. This work was supported by the Volkswagen Foundation.
Аннотация: Networks of superconducting Bi2Sr2CaCu2O8 (Bi-2212) nanowires were fabricated by the electrospinning technique. The nanowires have a diameter of the order of 150–200 nm and lengths up to the micrometer range and form a nonwoven, fabric-like network with numerous interconnections enabling a current flow between the nanowires. The porosity of this nanowire network is 0.9928. Therefore, this material represents a novel class of ultraporous high-temperature superconductors. The magnetizations of the nanowire networks [M(T) and M(H)] were recorded by SQUID magnetometry. The magnetic properties were analyzed using the extended critical state model (ECSM). It is supposed that the averaged diameter of the nanowires rules the magnetic field dependence of the critical current density of the nanowire network. Single nanowires have remarkably high values of the critical current density of 1.04×107A/cm2 at 5 K. The macroscopic critical current density less than ∼0.05A/cm2 at 5 K is fine for this lightweight material. Using ECSM, several important magnetic parameters could be determined including the penetration field Hp, the irreversibility fields Hirr, the upper critical field Hc2, and the flux pinning forces. Applications for this material class may be found in the direction of sensors, thin shielding layers, or nanoporous bulks.
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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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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Savitskaya N. E., Popkov S. I., Kuzmichev N. D., Vasyutin M. A., Balaev D. A.
Заглавие : Anisotropic magnetization of an NbN film
Место публикации : J. Exp. Theor. Phys. - 2022. - Vol. 134, Is. 6. - P.707-712. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776122060097
Примечания : Cited References: 31. - We are grateful to I.V. Nemtsev for measurements on the scanning electron microscope, S.A. Skorobogatov for his help in magnetic measurements (scanning electron microscopy and magnetic measurements have been performed at the Krasnoyarsk Regional Collective Usage Center of the Federal Research Center “Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences”)
Аннотация: The structural and magnetic properties of a niobium nitride (NbN) film prepared by reactive sputtering onto a quartz substrate are investigated. It is shown using scanning electron microscopy that the film has a columnar structure with a diameter of crystallite columns of about 50 nm. The film magnetization loops are measured for the field orientation parallel and perpendicular to its surface. Based on the experimental data, the critical current densities of the film are estimated in both cases. For the field parallel to the film surface, the estimate is 6.5 × 104 A/cm2 at the liquid helium temperature. For the field perpendicular to the surface, the critical current density is close to the depairing current density (107 A/cm2). Analysis of the results based on different models of magnetic vortex pinning in superconductors shows that in the former case, pinning occurs at the boundaries of columns in the bulk of the sample, while in the latter case, it is determined by the influence of the surface barrier.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Petrov M. I., Nemtsev I. V., Balaev D. A.
Заглавие : Anisotropy and crystallite misalignment in textured superconductors
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 1. - P.59-65. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06454-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project “Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements” No. 20–42–240008
Аннотация: A misalignment of anisotropic crystallites causes small values of anisotropy and decreases the critical current density of textured polycrystalline superconductors. To relate the crystallite misalignment and out-plane anisotropy, the magnetic properties of the textured Bi2223 polycrystalline superconductor were investigated. A distribution of orientation angles of crystallites was determined using different data: scanning electron microscopy images and hysteresis magnetization loops when an external magnetic field was applied at different angles with respect to the texturing plane of the sample. It was demonstrated that the standard deviation of the distribution and the magnetic disorder angle of crystallites in textured samples can be determined from the magnetization data in perpendicular directions. These data may be either the irreversible magnetization measured for two different orientations of the sample or the simultaneously measured magnetization projections parallel and perpendicular to the magnetic field.
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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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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Gokhfeld D. M.
Заглавие : Developing a concept of an effective field in the intergrain medium of a granular superconductor: Effect of the intragrain Meissner currents and Abrikosov vortices trapped in grains on the magnetotransport properties of a Y-Ba-Cu-O granular HTS
Колич.характеристики :18 с
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 7-9. - P.1631-1648. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06608-2. - ISSN 15571947 (eISSN)
Примечания : Cited References: 58. - The authors are grateful to M.I. Petrov, A.D. Balaev, and V.M. Sosnin for fruitful discussions and A.V. Shabanov and I.V. Nemtsev for scanning electron microscopy investigations. The scanning electron microscopy investigations and a part of magnetic measurements (performed on a LakeShore VSM 8604 facility) were carried out at the Krasnoyarsk Regional Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences. The study is performed within the state assignment of Kirensky Institute of Physics
Аннотация: Granular high-temperature superconductors (HTSs) are characterized by the hysteretic field dependences of magnetoresistance R(H) and critical current IC(H). These hysteretic effects are described within the concept of an effective field in the intergrain medium. The effective field is a superposition of external magnetic field H and the field induced by the magnetic moments of superconducting grains into intergrain spacings (grain boundaries). The magnetization of superconducting grains is determined by two contributions: Meissner (shielding) currents (MC) and trapped magnetic fluxes (Abrikosov vortices (AV)). To develop the concept of an effective field in the intergrain medium, the magnetotransport properties (R and IC) have been compared for two cases: (AV) the magnetization of superconducting grains is only determined by the trapped magnetic flux (zero external field) and (MC) HTS grains are in the Meissner state (the external field is weaker than the first critical field of grains). In a set of experiments, the main features of the hysteretic R(H) and M(H) dependences have been illustrated and the external conditions for implementing the AV and MC states have been established. It has been found that the effects of the Abrikosov vortices and intragrain Meissner currents on an effective field in the intergrain medium at the same magnetization values are noticeably different. This is a nontrivial fact that requires a thorough study of the impact of the anisotropy of the superconducting properties of grains on the configuration of the Meissner currents in them, as well as on the orientation of vortices both inside grains and near their surface. We suggest the explanation of observed stronger effect of the Meissner currents on the intergrain medium as compared with the effect of the Abrikosov vortices.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Gokhfeld D. M.
Заглавие : Influence of intragranular Meissner currents and magnetic flux trapped in granules on the effective field in the intergranular medium and the magnetoresistance hysteresis of a granular HTSC
Место публикации : Phys. Solid State. - 2022. - Vol. 64, Is. 12. - P.1846-1854. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2022.12.54376.442. - ISSN 10906460 (eISSN)
Примечания : Cited References: 61. - The study was carried out with the financial support of the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, the Krasnoyarsk areal Science Foundation within the framework of the scientific project No. 20-42-240008 ”The effect of the introduction of paramagnetic ions of rare earth elements on the superconducting properties of materials based on YBCO“. The study of the microstructure and magnetic measurements were carried out using the equipment of the Center for Collective Use of the FITC KNC SB RAS
Аннотация: The concept of an effective field in an intergranular medium is used to describe the hysteresis magnetoresistance of granular HTSCs. This effective field is a superposition of the external magnetic field and the field induced by the magnetic moments of the superconducting granules. The magnetic moment of the granules is contributed by the shielding currents and the trapped magnetic flux. We studied and analyzed the effect of the trapped flux on the magnetoresistance. It has been experimentally shown that the dependence of the residual resistance RRem (after applying of the external field) on the trapped flux clearly correlates with the behavior of the remanent magnetization. In addition, special attention was paid to a detailed comparison of the magnetoresistance of the granular YBa2Cu3O7-δ for two cases: (a) the magnetization of HTSC-granules is caused only by the trapped magnetic flux (in a zero external field) and (b) HTSC-granules are in the Meissner state (the external field is smaller than the first critical field of the granules). It has been found that Abrikosov vortices and intragranular Meissner currents differently affect the effective field in the intergranular medium (for the same values (of magnetization for cases (a) and (b) ). A possible reason for this difference is discussed.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Gokhfeld D. M.
Заглавие : New evidence of interaction between grain and boundaries subsystems in granular high-temperature superconductors
Место публикации : J. Supercond. Novel Magn. - 2021. - Vol. 34. Is. 4. - P.1067-1075. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-021-05812-2
Примечания : Cited References: 62
Аннотация: Granular high-temperature superconductors (HTSs) exhibit magnetotransport properties, including the clockwise magnetoresistance hysteresis. The hysteresis is explained by the concept of an effective field in the subsystem of grain boundaries, where the observed dissipation occurs. The effective field in the intergrain medium is determined by a superposition of the external field H and the field induced by the magnetic response of HTS grains. The magnetic flux compression in the intergrain medium provides an increase of the effective field. The magnetoresistance hysteresis of polycrystalline YBa2Cu3O7-δ has a bright feature: In a fairly wide external field range, the hysteresis width ΔH(H) is found to be almost linear, ΔH ≈ H. This behavior is considered to be universal over the entire temperature range corresponding to the superconducting state (the investigations have been carried out at temperatures of 77 K and 4.2 K). The analysis of the magnetoresistive and magnetic properties has shown that the upper boundary of the field range of the ΔH ≈ H regime is consistent with the field of complete penetration into HTS grains. This is indicative of the strong interrelation between the magnetotransport and magnetic properties of granular HTSs.
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13.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gokhfel'd D. M., Semenov S. V., Balaev D. A., Dubrovskiy A. A., Terent'yev K. Yu., Freydman A. L., Krasikov A. A., Petrov M. I.
Заглавие : Control of peak effect in YBCO by Nd substitution
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.O2.7. - P.140. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 4. - The work was supported by Russian Foundation for Basic Research Grant No.16-38-00400
Ключевые слова (''Своб.индексиров.''): peak effect--paramagnetic magnetization--bulk superconductors--critical current--irreversibility field
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Petrov M. I., Balaev D. A., Gokhfel'd D. M., Шайхутдинов, Кирилл Александрович, Ospishchev S. V., Aleksandrov K. S.
Заглавие : Crossover from the "clean" limit to the "dirty" limit in a network of S-N-S weak links in Y3/4Lu1/4Ba 2Cu3O7 + BaPb1-xSnxO 3 (0 ≤ x ≤ 0.25)
Место публикации : Phys. Solid State. - 2004. - Vol. 46, Is. 10. - P.1792-1797. - ISSN 1063-7834, DOI 10.1134/1.1809407
Аннотация: Composites with a network of "superconductor-normal metal-superconductor" (S-N-S) weak links are prepared from a Y 3/4LU1/4Ba2Cu3O7 high-temperature superconductor and BaPb1-xSnxO 3 (0 ≤ x ≤ 0.25) metal oxides. It is found that an increase in the tin content x in the nonsuperconducting component of the composite leads to an increase in the electrical resistivity ρ and, hence, to a decrease in the mean free path l of charge carriers. The temperature dependences of the electrical resistivity ρ(T) and critical current jC(T) of the composites are analyzed in the framework of the de Gennes theory of S-N-S junctions. It is demonstrated that the network of weak links in the composites is characterized by a crossover from the "clean" limit (l ≥ L) to the "dirty" limit (l ≤ L) (where L is the effective thickness of N interlayers between high-temperature superconductor grains). © 2004 MAIK "Nauka/Interperiodica".
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Belozerova I. L., Gokhfeld D. M., Kashkina L. V., Kuzmin Y. I., Michel C. R., Petrov M. I., Popkov S. I., Shaikhutdinov K. A.
Заглавие : Current-voltage characteristics of a foamed Bi1.8Pb0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Разночтения заглавия :авие SCOPUS: Current-voltage characteristics of a foamed Bi1.8Pb 0.3Sr2Ca2Cu3Ox high-temperature superconductor with fractal cluster structure
Место публикации : Phys. Solid State: SPRINGER, 2006. - Vol. 48, Is. 2. - P207-212. - ISSN 1063-7834, DOI 10.1134/S1063783406020016
Примечания : Cited References: 27
Предметные рубрики: T-C SUPERCONDUCTORS
NORMAL-PHASE
VORTEX MOTION
TRANSITION
TRANSPORT
VORTICES
Аннотация: The influence of the structure of foamed polycrystalline bismuth-based superconductors on their critical currents and current-voltage characteristics is studied. It is found that superconducting foams have a fractal structure, and the fractal dimension of the boundary between the normal and superconducting phases is estimated. The magnetic and transport properties of superconducting foams are investigated, and the current-voltage characteristics are obtained in a wide range of currents. The effect of percolation phenomena on vortex pinning in a foamed superconductor is considered. The current-voltage characteristics of the superconducting foams at the beginning of the resistive transition are found to be in good agreement with a model in which a magnetic flux is assumed to be trapped in the fractal clusters of a normal phase.
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16.

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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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Balaev D. A., Shaikhutdinov K. A., Popkov S. I., Petrov M. I.
Заглавие : Current-voltage characteristics of break junctions of high-Tc superconductors
Место публикации : Physica C: Superconductivity and its Applications: Elsevier Science Publishing Company, Inc., 2007. - Т. 467, № 1-2. - С. 80-84. - ISSN 0921-4534, DOI 10.1016/j.physc.2007.09.001
ГРНТИ : 29.01
РИНЦ
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18.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zeng X. L., Gokhfeld D. M., Karwoth T., Koblischka M., Hauet T., Hartmann U.
Заглавие : Detailed analysis of magnetization loops of electrospun non-woven superconducting fabrics
Коллективы : Deutsche Physikalische Gesellschaft Verhandlungen
Место публикации : Theses of Deutsche physikalische gesellschaft (Spring meeting). - 2017. - Ст.TT47.5
Аннотация: Networks of superconducting Bi2Sr2CaCu2O8 (Bi-2212) nanowires were fabricated by the electrospinning technique. The nanowires form a non-woven, fabric-like network with numerous interconnects enabling a current flow between the nanowires. The porosity of this nanowire network is 0.9928. Therefore, this material represents a novel class of ultraporous high-temperature superconductors. The magnetization of the nanowire networks were recorded by SQUID magnetometry. The magnetic properties were analyzed using the extended critical state model (ECSM). Single nanowires have remarkably high values of the critical current density of 1.69×107 A/cm2 at 5 K. The resulting sample critical current density of 7.44×104 A/cm2 at 5 K is fine for this lightweight material. Using the ECSM, several important magnetic parameters could be determined including the penetration field, Hp, the irreversibility fields, Hirr, the upper critical field, Hc2, and the flux pinning forces.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Gokhfeld D. M., Terent'ev K. Yu., Volochaev M. N., Petrov M. I.
Заглавие : Diffusion of strontium in the intergranular boundaries of La2–xSrxCuO4
Место публикации : Russ. J. Phys. Chem. A. - 2021. - Vol. 95, Is. 6. - P.1165-1168. - ISSN 00360244 (ISSN), DOI 10.1134/S0036024421060066
Примечания : Cited References: 11. - This work was supported by the Russian Science Foundation, project no. 17-72-10067
Аннотация: Energy dispersive X-ray spectroscopy and scanning electron microscopy are used to study La2CuO4–La1.56Sr0.44CuO4 composites with different annealing times. Maps of the strontium distribution for such systems are calculated and compared to experimental data obtained for the area of contact between two dissimilar granules. The coefficient of lattice diffusion of strontium is found. At the areas of contact between La2CuO4 and La1.56Sr0.44CuO4 granules, the strontium concentration corresponds to superconducting phase La2−xSrxCuO4 with x = 0.05–0.25. The technological parameters of synthesis affect the size and number of superconducting and normal regions. Prolonged annealing lowers the gradient of the strontium concentration, which halts the increase in the size of the superconducting regions. This saturation confirms the diffusion front model.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bykov A. A., Gokhfeld D. M., Altynbaev E. V., Terent'ev K. Yu., Martin N., Semenov S. V., Grigoriev S. V.
Заглавие : Effect of Trapped Magnetic Flux on Neutron Scattering in La1.85Sr0.15CuO4 Superconductor
Место публикации : J. Supercond. Novel Magn. - 2019. - Vol. 32, Is. 12. - P.3797-3802. - ISSN 15571939 (ISSN) , DOI 10.1007/s10948-019-05195-5
Примечания : Cited References: 25. - The authors are grateful to G.P. Kopitsa and V.V. Runov for fruitful discussions.The work is supported by the Russian Science Foundation (project No. 17-72-10067).
Аннотация: The superconducting La1.85Sr0.15CuO4 ceramics has been studied by small angle neutron scattering, magnetization measurements, and scanning electron microscopy. Experiments have shown that the intensity of the magnetic scattering is 2–3 times higher in the field cooled regime than in the zero-field cooled regime. Additional magnetic heterogeneities due to closure of the trapped magnetic flux cause the excess scattering in the field cooled regime. The isotropic nature of the scattering is associated with the absence of a preferred direction of the Abrikosov vortices, which is caused by the random orientation of the ab planes of the anisotropic superconductor granules.
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