Tuesday, 08/19/08

Session Title:	Flux Pinning and Dynamics II - Engineered Pinning Arrangements
Session Chairs:	Paul Barnes, Air Force Research Laboratory, Wright-Patterson AFB & Takanobu Kiss, Kyushu University
Paper Number:	2MPD02
Start Time:	10:00am
Session Type:	Poster

Pinning centres induced in YBCO films by nano-dots in substrate decoration and quasi-superlattice approaches P. Mikheenko, A. Sarkar, V.S. Dang, J.L. Tanner, M.M. Awang Kechik, J.S. Abell, A. Crisan, University of Birmingham, UK

For power applications of superconducting films, the critical current density (J_c) and the thickness of the film should be as high as possible. J_c decreases with both thickness and magnetic field, so artificial pinning centres in addition to natural ones are required. The earliest cost-effective method used for introducing artificial pinning centres was the so-called substrate decoration, i.e., growing nanoscale islands (nano-dots) of certain materials on the substrate prior to the deposition of the superconducting thin film. Later on other two approaches proved to be successful: bulding up a layered distribution of a second phase using a multilayer deposition (quasi-superlattices), and, respectively, by distribution of a secondary phase as a result of a compositional change in the target. Several materials have been used till now for the creation of artificial pinning centres. Here we report on the artificial pinning centres induced in YBCO films and multilayers by decorating the substrate with Au nano-dots and, respectively, by a layered distribution (up to 7 layers) of Au nano-dots inside thick YBCO films. The effect of film thickness and nano-dots induced pinning centres on the critical current density will be discussed. Cross-sectional AFM images show evidence of c-axis correlated columnar defects.