Mesoscopic superconducting disc with short-range columnar defects

Short-range columnar defects essentially influence the magnetic properties of a mesoscopic superconducting disc. They help the penetration of vortices into the sample, thereby decreasing the sample magnetization and reducing its upper critical field. Even the presence of weak defects split a giant vortex state (us;ally appearing in a clean disc in the vicinity of the transition to a normal state) into a number of vortices with smaller topological charges. In a disc with a sufficient number of strong enough defects, vortices are always placed onto defects. The presence of defects leads to the appearance of additional magnetization jumps related to the redistribution of vortices which are already present on the defects and not to the penetration of new vortices. [S0163-1829(99)03318-4].