Dependence of Jc on pinning center morphology: An explanation of record Jc observed for discontinuous columnar pinning of vortices

An experimental study of defects caused by ion irradiation has proven that very discontinuous multiple-in-line-damage results in much higher Jc than continuous columnar pinning centers. This is contrary to conventional wisdom. We develop a first approximation to a theory relating Jc to the morphology of pinning centers. Qualitative agreement with experiment is achieved. Conclusions indicate the relative importance of pinning potential, percolation, and critical temperature for various morphologies. Results suggest the leading importance of pinning, compared to texture, weak links and oxygenation in achievement of the goal of high Jc especially in large grain HTS.