Browsing by Author "Djupmyr, Märit"

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    The role of temperature for the critical current density in high temperature superconductors and heterostructures
    (2008) Djupmyr, Märit; Schütz, Gisela (Prof. Dr.)
    This work concentrates on the study of high-temperature superconducting thin epitaxial films composed of YBCO. Further, in the second part a ferromagnetic layer of LCMO is added to the superconductor. All the films were investigated with a magneto-optical technique capable of directly imaging the critical current distribution in the sample. Mainly temperature dependent measurements were performed. By applying a systematical quantitative analysis of the temperature dependent critical current, different flux-pinning mechanisms could be identified to limit the critical current in different temperature regimes. Comparison of films with different defect structures, prove the strong connection between microstructure, interfaces and critical currents. Equal investigations of heterostructures to those of the superconducting films show a strong influence of the ferromagnet on the critical current. This is explained by the penetration of an inhomogeneous stray field distribution from the ferromagnet through the superconducting layer.