Two-dimensional growth of atomically smooth YBCO epitaxial films deposited by PLD in a pulsed oxygen flow

The employment of superconducting thin films as electronic devices seems to be the most probable future application of these materials. For this application, thin films with extremely smooth surface and very good superconducting as well as structural properties are required. We deposited YBCO epitaxial thin films by pulsed laser ablation using a pulsed molecular oxygen flow synchronous with the arrival of the ablated species on the substrate. We studied the dependence of their surface morphology on the deposition pressure and we found an evident improvement in the surface quality by lowering the deposition pressure below 5 × 10 -3 mbar. Films grown in these conditions showed surface roughness lower than 1 Å, transition temperatures above 88 K and critical current densities of about 10 7 A cm -2 at 4.2 K in self-field.