Formation of columnar defects in high-T-c superconductors by swift heavy ions

Experimental data on the variation of the size of columnar defects with the electronic stopping power S-e are analyzed for Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O. A model is applied that is based on the thermal spike concept and which was previously successfully used for irradiated insulating materials. The width of the thermal spike a (0) obtained from the analysis is 4.4 and 4.65 nm for Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O, respectively, which are in good agreement with the value for insulators. The fraction of the energy deposited to the thermal spike in the phonon system gS(e) is lower in high-T-c superconductors (HTCS's) than in insulators, This reduction is attributed to the anisotropy of the electron scattering. The model is suitable to predict the size of columnar defects in HTCS's.