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Вид документа : Статья из журнала Шифр издания :
Автор(ы) : Balaev D. A., Bykov A. A., Semenov S. V., Popkov S. I., Dubrovskii A. A., Shaikhutdinov K. A., Petrov M. I.
Заглавие : General regularities of magnetoresistive effects in the polycrystalline yttrium and bismuth high-temperature superconductor systems
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 5. - P922-932. - ISSN 1063-7834, DOI 10.1134/S1063783411050052 Примечания : Cited References: 52. - This study was supported by the Russian Academy of Sciences within the program no. 5 (project no. 7).
Предметные рубрики: HIGH MAGNETIC-FIELDS PHASE-SLIP RESISTIVE TRANSITION CU-O TRANSPORT-PROPERTIES JOSEPHSON MEDIUM MIXED-STATE FLUX-CREEP T-C DISSIPATION Аннотация: The influence of thermomagnetic prehistory on the behavior of a resistive transition R(T) in external magnetic fields of polycrystalline YBa(2)Cu(3)O(7) and Bi(1.8)Pb(0.3)Sr(1.9)Ca(2)Cu(3)O (x) high-temperature supercon-ductors and the Bi(1.8)Pb(0.3)Sr(1.9)Ca(2)Cu(3)O (x) + Ag texture has been investigated. It has been found that, for YBa(2)Cu(3)O(7), the thermomagnetic prehistory exerts a substantial influence on the dissipation in the subsystem of grain boundaries in magnetic fields up to similar to 10(3) Oe, and this effect becomes insignificant in fields higher than similar to 10(4) Oe. This behavior has been explained by the influence of magnetic moments of high-temperature superconductor grains on the effective magnetic field in the intergranular medium. For bismuth high-temperature superconductors, no influence of thermomagnetic prehistory on the resistive transition has been observed; however, this effect manifests itself in current-voltage characteristics at high transport current densities. There is also a radical difference in the behavior of isotherms of the magnetoresistance R(H) for the yttrium and bismuth systems. For YBa(2)Cu(3)O(7), there is a clear separation between the dissipation regimes in the intergranular medium and in grains, which manifests itself even at low transport current densities as a change of sign in the curvature of the dependence R(H). For a texture based on the bismuth high-temperature superconductor, this feature has been observed only at high current densities (comparable to the critical current density at H = 0). This difference in the behavior of magnetoresistive properties of the classical high-temperature superconductor systems under investigation has been explained by relatively low irreversibility fields of the bismuth high-temperature superconductors. In these materials, simultaneous processes of dissipation can occur in an external magnetic field both in the subsystem of grain boundaries between crystallites and in the crystallites themselves.
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