Combining Near-Field Scanning Microwave Microscopy With Transport Measurement for Imaging Current-Obstructing Defects in HTS Films

Identification of defects that obstruct electrical current in high-temperature superconductors (HTS) is of great importance for applications. A technique that combines near-field scanning microwave microscopy (NSMM) with transport measurement was developed to obtain multiple sets of complementary maps on the same sample area. This technique takes advantage of the NSMM´s unique capability to function both as an EM wave emitter that can locally heat a spot on a current-biased sample and also as a detector to map the spatial non-uniformity in electromagnetic properties of the sample including loss, dielectric constant, and surface morphology. Macroscopic defects in YBa₂Cu₃O_7-delta (YBCO) films were clearly identified and imaged using this technique with adequate sensitivity and resolution.