A collaboration of researchers in Japan report on four years of extensive research into superconductivity, including the materials that were found not to have superconducting properties, as well as those that were, and their potential for wires and devices.
Materials that superconduct at more practical temperatures than liquid helium are in high demand, both for the insights in fundamental physics they may reveal and their device potential. A review published in Sci. Technol. Adv. Mater. Vol. 16 (2015) p. 033503 by a collaboration of researchers in Japan now provides a detailed overview of the past four years extensive research on around 1000 materials, with detailed insights learnt from the new superconducting materials discovered. A unique feature of this review is incorporation of a lost of the roughly 700 studied materials that did not show superconductivity.
"This is probably the first such paper with opening of a list of experiments that failed," says Hideo Hosono, a researcher at Tokyo Institute of Technology and first author of the review. It should be invaluable data for researchers in the field."
Existing theory offers little that helps identify high-temperature conductors, leaving a vast array of material possibilities. "We decided to not to waste the time and effort of other researchers, and wrote this paper with the results of samples that did not go superconducting," adds Hosono, who also led the research behind the first discovery of iron-based superconductors in 2006.
The research team members were also unique for a project in superconductivity since their research expertise emphasised solid-state chemistry over condensed-matter physics. They included researchers from Tokyo Institute of Technology, the International Superconductivity Research Center, the National Institute of Materials Science, Kyoto University, Hiroshima University, and Okayama University.
In the past, similar research projects have been strictly focused on finding superconducting properties, resulting in an all or nothing outcome, and at the time the work in the review was carried out, funding for superconductivity research was in decline. Instead Hosono and his colleagues employed a flexible approach that led to valuable insights into other material properties, such as ammonia catalysis for fertilizer production, ambipolar oxide thin film transistors and metallic ferroelectricity.