Critical current density of Bi 2Sr 2Ca 1Cu 2O δ monocore and multifilamentary wires from 4.2 K up to Tc in high magnetic fields

Abstract

The transport critical current density ( J c) of a mono, 19 and 37 filament Bi 2Sr 2Ca 1Cu 2O δ wire has been measured in high fields at temperatures of 4.2 K up to 80 K. Measurements were made with the field applied parallel and perpendicular to the wire axis. The low-temperature high-field J c values for the 19 and 37 filament wires are similar and markedly higher than the monocore wire. The data have been analyzed in terms of pinning-force functions and an exponential field function. In low fields, below 40 K, the volume pinning force is given by a power law of the form F p ∝ B 3 4 . In high fields, the functional form is given by J c( B, T) = α( T) exp[ − B/ β( T)]. The parameters α( T) and β( T) are measured for the three wires and compared with those of a monocore Bi 2− x Pb xSr 2Ca 2Cu 3O δ silver-shathed tape.