Vortex pinning and flux creep in Bi<sub>2</sub>Sr<sub>2</sub>(Ca<sub>1-x</sub>R<sub>x</sub>)Cu<sub>2</sub>O<sub>8+y</sub>(R=Y,Gd)
P A J de Groot; R A Rose; B Jayaram; G P Rapson; M Guillot; P A J de Groot; Dept. of Phys., Southampton Univ., UK; R A Rose; Dept. of Phys., Southampton Univ., UK; B Jayaram; Dept. of Phys., Southampton Univ., UK; G P Rapson; Dept. of Phys., Southampton Univ., UK; M Guillot; Dept. of Phys., Southampton Univ., UK
Журнал:
Superconductor Science and Technology
Дата:
1991-01-01
Аннотация:
The authors present magnetisation measurements on powders of Bi<sub>2</sub>Sr<sub>2</sub>(Ca<sub>1-x</sub>R<sub>x</sub>)Cu<sub>2</sub>O<sub>8+y</sub> (R=Y,Gd). The observed magnetic relaxations and the field dependence of the pinning force have been described in terms of a thermally activated flux-creep model without the need to consider phase transitions of the vortex system. They have found that the intra-grain J<sub>c</sub> decreases rapidly with rare earth or Y substitution. Even in the concentration range for which T<sub>c</sub> remains constant, J<sub>c</sub> decreases: J<sub>c</sub>(x=O)/J<sub>c</sub>(x=.32)=5.7.
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