M Dhallé et al 1997 Supercond. Sci. Technol. 10 21 doi:10.1088/0953-2048/10/1/004
M Dhallé
, M Cuthbert
, M D Johnston
, J Everett
, R Flükiger
, S X Dou§, W Goldacker||, T Beales
,
and A D Caplin![]()
The current - voltage characteristics and the magnetic field dependence of the critical current of a range of mono-core BSCCO 2223 tapes are presented, illustrating the complementary use of transport and magnetization experiments in determining and analysing the current-limiting dissipation processes in these HTS conductors. Below a magnetic cross-over field
the samples resemble a Josephson-linked current network, with the dominant dissipation at the weakest grain boundaries. In this regime, increasing field leads to a gradual fragmentation of the network. The network homogeneity and connectivity can be inferred from screening current length-scale measurements and comparison of transport and magnetization measurements. Above the cross-over field
, flux motion within the surviving strongly linked backbone dominates the dissipation. The details of the dependences of the critical current and flux creep rate on magnetic field can be used to examine the intragranular pinning potential in the tapes. We show that, despite the wide range of transport critical-current values of the samples examined, the intragranular pinning proves to be remarkably sample independent. We conclude that while
at low fields may be increased by improved processing that yields better intergrain connectivity, the high-field
can be enhanced only by strengthening the pinning within the BSCCO 2223 crystallites themselves.
84.71.Mn Superconducting wires, fibers, and tapes
74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
74.25.Qt Vortex lattices, flux pinning, flux creep
85.25.Am Superconducting device characterization, design, and modeling
Issue 1 (January 1997)
Received 27 August 1996
M Dhallé et al 1997 Supercond. Sci. Technol. 10 21
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