Scanning Hall-probe microscopy for site-specific observation of microstructure in superconducting wires and tapes for the clarification of their performance bottlenecks

This paper reports a diagnostic method for clarifying performance bottlenecks in superconducting wires and tapes for their further performance enhancements. In particular, our achievements by scanning Hall-probe microscopy (SHPM), which worked well for selecting positions for microstructure observation by SEM, TEM, and x-ray CT, are introduced. This hybrid microscopy offers the information of the direct relationship between the performance of a practical-scale superconducting wire or tape and its origin in micro-scale or nano-scale structure. As such examples, characterization results for an MgB₂ multi-filamentary wire, a commercially available long RE-123 coated conductor, and a striated multi-filamentary coated conductor are reported in this paper through reviewing our past studies.