Рубрики:
HIGH MAGNETIC-FIELDS
PHASE-SLIP
RESISTIVE TRANSITION
CU-O
TRANSPORT-PROPERTIES
JOSEPHSON MEDIUM
MIXED-STATE
FLUX-CREEP
T-C
DISSIPATION
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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Держатели документа:
[Balaev, D. A.
Bykov, A. A.
Semenov, S. V.
Popkov, S. I.
Dubrovskii, A. A.
Shaikhutdinov, K. A.
Petrov, M. I.] Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Akademgorodok 50, Krasnoyarsk 660036, Russian Federation
Доп.точки доступа:
Balaev, D. A.; Балаев, Дмитрий Александрович; Bykov, A. A.; Быков, Алексей Анатольевич; Semenov, S. V.; Семенов, Сергей Васильевич; Popkov, S. I.; Попков, Сергей Иванович; Dubrovskii, A. A.; Дубровский, Андрей Александрович; Shaikhutdinov, K. A.; Шайхутдинов, Кирилл Александрович; Petrov, M. I.; Петров, Михаил Иванович