Influence of sequential etching on YBCO films deposited by PLD from a nanostructured target

摘要

Thin YBa2Cu3O6+x (YBCO) films with Tc = 90 K and high critical current in the order of 107 A/cm2 at 77 K are prepared with pulsed laser deposition from a nanostructured target. Changes in the superconducting and structural properties of the films are investigated after repeated thinning by Ar-ion sputtering or by electrochemical etching. As shown by Auger depth profiling, the chemical composition is preserved through the film during Ar-ion sputtering while electrochemical etching changes the atomic concentrations and surface structures. Investigations by SQUID magnetometry and by conventional resistivity measurements give evidence that the dependence of Tc on the film thickness is similar to as-prepared ultrathin films. The thickness dependence of Jc indicates an excess of pinning centers on the surface of the as-deposited film.