Surface nanostructuring and damage morphologies along 2GeV gold-ion-implanted tracks.

Good-quality melt-textured YBa[sub 2]Cu[sub 3]O[sub 7-x] materials with Y[sub 2]BaCuO[sub 5] nonsuperconducting inclusions were irradiated with 2GeV gold ions in order to produce a surface layer with columnar defects. The final goal is to gain a basic understanding of the role of the surface columnar defects in determining those magnetic properties of the materials that are related to the vortex confinement. The particle energy and the sample thickness were chosen in such a way that the percentage of irradiated volume is about 10%. In the paper the intrinsic structure and the damage morphology were analysed by means of transmission electron microscopy studies in both cross-section and plan-view geometry. As a result, the columnar defect density, size and shape were obtained. The irradiation produces parallel heavily damaged tracks whose diameter is between 3 and 6 nm. The overlapping of some columnar defects was highlighted and had to be taken into account to understand the superconducting properties of irradiated samples. The defects affect an implanted layer of about 50mum. The measured thickness coincides, within the experimental errors, with the thickness calculated by means of the Monte Carlo TRIM simulations. [ABSTRACT FROM AUTHOR]