Processing high-T_c superconductors with GeV heavy ions

Abstract

Irradiation of high-Tc superconducting crystals with low doses (1010-1011 ions/cm2) of GeV heavy ions produces a unique microstructure consisting of discrete amorphous columns which are only a few nm in diameter but tens of μm long. It has been found recently that this columnar microstructure causes larger increases in magnetization and critical current at high temperature and high magnetic field than other types of defects in these materials. This can be understood as a consequence of the effective pinning of magnetic vortex lines provided by the columnar defects. Measurements confirm that the pinning is strongest when the magnetic field is aligned with the ion tracks. Differences in the pinning in different materials can be related to differences in their anisotropy, which affects the structure of the vortices and their pinning at columnar defects. © 1993.