The effect of splayed columnar defects on the magnetisation of Bi2Sr2Ca2Cu3O10/Ag tapes

Abstract Columnar defects are known to provide excellent flux pinning sites in high T c superconductors. The changes in pinning properties of Bi 2 Sr 2 Ca 2 Cu 3 O 10 /Ag tapes due to perfectly splayed amorphous tracks were examined measuring the DC magnetisation versus temperature T and magnetic field H . We compare the hysteretic magnetisation ΔM ( T , H ) and the magnetic relaxation rate S ( T , H ) before and after irradiation. The data show how played columnar defects indeed increase the pinning strength at high temperature, but enhance vortex motion at low temperature. We attribute the cross-over between these two regimes to a change in vortex dimensionality.