Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 8: Postersitzung I: Supraleitung
TT 8.32: Poster
Montag, 8. März 2004, 14:30–19:00, Poster A
Magnetic Properties of YBa2Cu3O7 Ring Structures — •K. Schindler1, M. Ziese1, P. Esquinazi1, H. Hochmuth2, M. Lorenz2, E. Salamatin3, and K. Zimmer3 — 1Division of Superconductivity and Magnetism, University of Leipzig, 04103 Leipzig. — 2Semiconductor Physics Group, University of Leipzig, 04103 Leipzig. — 3IOM, Institute for Surface Modification, 04318 Leipzig.
YBa2Cu3O7 (YBCO) films were grown by pulsed laser deposition on CeO2-buffered r-plane sapphire substrates. Film thickness was 260 nm; the films were covered with a gold layer of 220 nm. From a single 3 inch wafer various ring structures were fabricated using photolithographical techniques and subsequent etching with either an Excimer laser or an ultrafast Ti:sapphire laser, respectively. The magnetic properties of the YBCO ring structures were investigated by ac-susceptibility and SQUID magnetometry. In order to quantify and assess the material damage introduced by the different etching techniques, the critical current density of 12 single rings with 2 mm outer diameter and ring widths between 15 and 110 µm was determined by magnetic field dependent ac-susceptibility measurements. The complex susceptibility of the rings at least up to the 13th harmonic could be accurately modelled within a critical state model. The values of the critical current density extracted did not show a systematic dependence on the patterning technique. Furthermore, structures with 1024 rings of outer diameter 20 µm and ring width 1 and 2 µm were investigated. FC-, ZFC- and remanent magnetization measurements were used to determine the volume of shielded material. The data will be further discussed within a critical state model.