Perpendicular transport properties of YBa2Cu3O7−δ/PrBa2Cu3O7−δ superlattices

Abstract

The coupling between the superconducting planes of YBa2Cu3O 7−δ / PrBa2Cu3O 7−δ superlattices has been measured by c-axis transport. We show that only by changing the thickness of the superconducting YBa2Cu3O 7−δ layers, it is possible to switch between quasi-particle and Josephson tunneling. From our data we deduce a low temperature c-axis coherence length of ξc = 0.27 nm. Artificial YBa 2 Cu 3 O 7−δ /PrBa 2 Cu 3 O 7−δ superlattices (Y123/Pr123) constitute ideal model systems for isolating given properties of High Temperature Superconductors. In those systems it is possible for instance to modify the c-axis tunneling properties simply by varying the periodicities of the Y123 and Pr123 layers.Series of 200 nm thick Y123/Pr123 superlattices have been prepared by high-pressure dcsputtering. The high quality of the samples was checked by detecting up to third order satellite peaks in x-ray θ − 2θ scans. Later on series of mesa structures with dimensions between 15 × 15 and 50 × 50 µm 2 were prepared by ion milling. In this work we present low temperature data on 2:7 (2 layers of Y123 and 7 of Pr123) and 8:8 superlattices.