Magneto-optical study of flux-line pinning in superconductors with linear defects

Abstract

Linear defects were introduced in high-temperature superconductor single crystals by high-energy heavy-ion irradiation. Different geometrical arrangements, such as parallel settings of linear defects perpendicular and inclined to the sample surface by a planar angle ϕ as well as crossed linear defects were produced. Magneto-optical study of flux penetration into the crystals revealed a strong dependence of the irradiation-induced critical-current enhancement on the defect arrangement. It was found that crossed linear defects in general provide better flux-line pinning than parallel ones. The optimal crossing angle is around 5°.