PILLAR DEFECTS, A NEW-TYPE OF TRACK IN PB-IRRADIATED BI-2212 THIN-FILMS - NANOSTRUCTURAL STUDY AND INFLUENCE ON THE IRREVERSIBILITY LINE

Bi-2212 thin films have been irradiated by 936 MeV Pb ions. An High Re solution Electron Microscopy (HREM) study revealed the formation of sq uare based defects, the so-called pillar tracks, extending throughout the thickness of the film and coexisting with columnar defects of same size. The pinning efficiency of this mixed structure of defects has b een investigated by magnetic measurements and compared to a structure containing only columnar defects of the same size. This comparison sug gests that pillar defects act the same way as columnar defects of abou t the same size (125 Angstrom). (C) 1998 Elsevier Science B.V. All rig hts reserved.