Critical Current Density of Narrow Superconducting Thin Films Fabricated by Laser Ablation Techniques

The variations of critical current density Jc of narrow Y‐Ba‐Cu‐O films as a function of temperature and magnetic field are investigated. Films with thickness of 150‐200 nm and width of 20‐100 urn were prepared by laser ablation and laser etching. For t (=T/TC) < 0.75, the temperature dependence of Jc shows a (1‐1) linear behavior, in sharp contrast to that of a Josephson junction. Near Tc, Jc varies with (1‐ t)n where n=3/2 or 2 depending on the morphology of films. The magnetic field dependence of Jc above a characteristic field value Hc’ can be described by a model based on flux creep.