High temperature superconductors are arguably the most complicated materials under technological development today. They contain up to 5 chemical elements; have large, complex unit cells; and must be properly doped. They must be well ordered crystallographically in order to exhibit good superconducting properties, and yet they must contain suitable nanoscale defects in order to provide the vortex pinning necessary to carry large critical currents. It is a tribute to the worldwide effort of the international high Tc superconductivity (HTS) community over the last decade that these materials are currently being included in products offered for sale commercially. Indeed, the success of the superconducting materials community in developing techniques and tools capable of fabricating these materials into useful thin film devices and circuits has revolutionized the science and technology of thin films of complex oxides generally. Ferroelectric, piezoelectric, colossal magnetoresistive, and nonlinear optical thin film technologies have all benefited enormously. Despite this success, the materials problems associated with the high temperature superconductors remain formidable and are likely the largest purely technical problem blocking the promise of high temperature superconductivity. Table 3.1 gives a partial listing of these problems in the area of superconducting electronics.
With this background in mind, the WTEC panel examined HTS materials research in Japan from relevant basic research to manufacturing and scale-up. In this chapter we report our findings and compare the current situation in Japan and the United States.