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|Type:||Artigo de periódico|
|Title:||Quantum Creep Of Josephson Intergrain Vortices In Bi2sr2ca2cu3o10|
|Abstract:||Magnetic relaxation caused by the creep of Josephson intergrain vortices is studied in Bi2Sr2Ca2Cu3O10 high-Tc superconductor in the temperature interval 1.8 - 30 K for applied magnetic fields between 15 and 25 Oe. It is found that the magnetic moment M logarithmically decays with time t. At high enough temperatures the normalized logarithmic decay rate S = - (1/MJ0)(dMJ/dlnt) linearly increases with temperature, while at T < T0(H), a temperature -independent relaxation rate S ≈ 1.7-10-3 is found, manifesting the occurrence of quantum creep of the Josephson vortices. The "crossover" temperature T0 from the quantum tunneling to the classical thermally activated regime of the vortex motion rapidly decreases from T0 = 10 K to T0 < 2 K when the field is increased from H = 15 Oe to H = 25 Oe. No thermal enhancement of the tunneling rate was found in contrast to the quantum creep behavior of Abrikosov intragrain vortices measured in the same sample (Physica C 222 (1994) 149).|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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