Distribution of the local properties in HTSC (High-temperature superconductor) coated conductors was investigated using Low-temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). We prepared GdBCO and YBCO coated conductors to study the spatial distribution of local critical temperature and current density in a single bridge. Inhomogeneity of the local critical temperature Tc-max in the bridge was analyzed from experimental results of Scanning Laser Microscopy (SLM) near the superconducting transition. The local transport and screening current in the bridge were also investigated using SLM and Scanning Hall Probe Microscopy (SHPM). A series of linescans of SLM of the GdBCO and YBCO sample showed that lines with more inhomogeneous distributions of delta V had large standard deviation of Tc-max. As a result, distribution of delta V related to distribution of the critical temperature. The transverse defect of the superconducting layer of the GdBCO sample caused by damage to the substrate affected the current flow. The bias and screening current made a detour around the defect and the concentration of the current density was observed both studied of SLM and SHPM. We could analyze the redistribution of the current density using SLM and SHPM. We also investigated the redistribution of the bias current influenced by the external magnetic field in YBCO sample. If a magnetic field was applied to the current biased-sample, most of the bias current converged on the middle of the bridge where the smallest screening current flowed. In transport measurement, we could analyze local properties of the HTSC sample under the current and field applied regime using LTSLHPM.
Thesis Advisor: Prof. Hyeong-Cheol Ri