Two-year progress in experimental investigation on high-temperature superconductivity of sulfur hydride

The cooperation between theoretical and experimental investigations broke the record for the superconducting critical temperature T-c in hydrogen sulfide at a high pressure at the end of 2014. Surprisingly, the material improved its highest T-c by more than 30K and showed conventional superconductivity, which can be explained by the Bardeen-Cooper-Schrieffer theory. Recent experimental works have gradually clarified the instability of the H2S molecule and the pathway to the high-T-c phase with a three-dimensional conductive structure unlike high-T-c superconductors thus far. In this review, the present progress on a sulfur hydride system is reported. (C) 2017 The Japan Society of Applied Physics