Imaging of the Local Dissipation in YBCO Coated Tapes

Current transport properties in YBCO coated tapes have been studied by the low temperature scanning laser microscopy (LTSLM) as well as the four‐probe method. The LTSLM measurement allows us to visualize the local resistive transition with a spatial resolution of a few μm. It has been shown that the localized resistive region percolates into the sample as the bias current density is increased. From the LTSLM measurements, we can estimate the spatial distribution of the inhomogeneous Jc. Relationship between the local Jc distribution and the global E‐J characteristics has also been investigated. The percolation probability obtained based on the LTSLM measurement agreed quantitatively with that of the four‐probe measurement. Namely, those two measurements support the percolation model.