2-DIMENSIONAL BEHAVIOR OF YBA2CU3OX FILMS ON SRTIO3 SUBSTRATES

Long-term (up to 18 months) degradation of textured YBa2Cu3Ox films pr epared by laser ablation and magnetron sputtering on single crystal Sr TiO3, MgO and Al2O3 substrates were investigated. All films at each st age of exposition displayed a clearly visible quasi-2D behavior. From tile measurements of the Kosterlitz-Thouless temperature it could be c oncluded that the oxygen content and density of charge carriers remain ed constant. It follows that the main consequence of degradation is ti le omission of some planes from the transport of supercurrent and the samples could be described ill the model of layered structure with var iable number of conducting planes. Using this model we find that effec tive thickness of an isolated CuO2 plane in samples with greatest inte rnal damage is d approximate to 3 Angstrom.