Enhancement of critical current by post-annealing of thin YBCO films prepared by laser ablation from a nanocrystalline target

Influence of post-annealing oil surface morphology and superconducting properties of thin YBCO films prepared by laser ablation from a. nanocrystalline target is investigated. Annealing of the films in slowly flowing oxygen at the optimum temperature of 900 degrees C increases the superconducting transition temperature T-c at best from 82 K (as-deposited film) to 90 K (annealed film). Also the critical current density rises remarkably during annealing, reaching the value of J(c) approximate to 1.4 x 10(7) A/cm(2) at 77 It in zero magnetic field; A plausible mechanism is discussed for explanation of these observations. The main surface defects found on the annealed films are a few large particles and holes. Between these defects the rms smoothness of the surface is 3.6 nm.