Effective Measuring Position of Hall Probe and jc Characterization of Rectangular HTS Thin Films

Scanning Hall probe (SHP) system is a powerful instrument to investigate the planar distribution of areal critical current density (j(c)) and defects of high temperature superconducting (HTS) thin film samples. The distance between the effective measuring position and probe bottom (h(1)) is usually unknown for the commercialized Hall probes. However, h(1) value has a significant influence on the measurement results, according to the calculation of the magnetic flux density (B-0) above the planar center of a rectangular HTS thin film sample. In this paper, a method was proposed to obtain h(1) by using a series of copper strips and analyzing the relationship of B-0 against the parameters, such as sample width and current. Then, SHP system was employed to characterize the j(c) distribution of an HTS thin film fabricated via chemical solution deposition. The relationship of B-0 and h(1) could also be utilized to obtain the average j(c) value (j(c)(B0)). A series of commercialized coated conductor samples were measured with both SHP and the traditional four-probe method. The feasibility of preliminary evaluation for rectangular HTS thin film samples by using j(c)(B0) was discussed based on its correlation with the results of four-probe method.