Measurement of local current flow around transverse defects in YBCO film by use of scanning SQUID microscope

Nonlinear current flow around artificial defects in YBCO epitaxial film has been investigated by use of scanning SQUID microscope. Two-dimensional local current flow around the transverse defects in the YBCO film has been visualized successfully from the magnetic self-field image. Experimental results showed good agreement with theoretical solution based on the Maxwell’s equation along with nonlinear current–voltage characteristics. Present method allows us to measure the non-uniform current flow quantitatively under the influence of obstacles in the micro-meter length scale.