Influence of randomly oriented columnar defects on the irreversible and reversible magnetization of Tl₂Ba₂CaCu₂O_x superconductor

Abstract

Bulk polycrystalline Tl2Ba2CaCu2Ox materials were irradiated with 0.8 GeV protons to introduce randomly oriented columnar defects. Proton fluences up to 8.7 × 1020 m-2 were used to create defect arrays corresponding to a 'matching field' of 1.5 T. Studies were conducted on the superconductive transition temperature, the Meissner fraction, the intragrain persistent current density against the magnetic field and temperature, and the equilibrium magnetization. The magnetization was modelled using London theory with the addition of vortex-defect interactions, yielding physically reasonable parameters.