Key compound for high-temperature superconductivity found

A research group in Japan found a new compound H₅S₂ that shows a new superconductivity phase on computer simulation. Further theoretical and experimental research based on H₅S₂ predicted by this group will lead to the clarification of the mechanism behind high-temperature superconductivity, which takes place in hydrogen sulfide .

Superconductivity is the total disappearance of electrical resistance when an object is cooled below a definite temperature. If superconductor is used for electric wire, it becomes possible to carry electricity without loss. That's why superconductivity has been drawing attention as an important physical phenomenon for solving environmental and energy problems.

However, the superconducting critical temperature, the temperature at which superconductivity takes place, is so low that its practical realization is difficult. Last year, a striking news came out that H2S broke the record for superconducting critical temperature under high-pressure. However, the chemical composition ratio of sulfur and hydrogen and the crystal structure during the process in which superconductivity takes place have not been well understood.

A research group led by Takahiro Ishikawa, Specially Appointed Assistant Professor, and Katsuya Shimizu, Professor, at Center for Science and Technology under Extreme Conditions, Graduate School of Engineering Science, Osaka University, Tatsuki Oda, Professor at School of Mathematics and Physics, Kanazawa University, and Naoshi Suzuki, Professor at Faculty of Engineering Science, Kansai University predicted a new superconductivity phase of hydrogen sulfide (H₅S₂), which was presented at a pressure of 1.1 million bar on computer simulation. The superconducting critical temperature obtained from H₅S₂, whose calculated value was the same as the experimental value. This result may lead to the clarification of the mechanism behind high-temperature superconductivity, which takes place in hydrogen sulfide by further theoretical and experimental research based on H₅S₂.

Furthermore, by applying methods used and knowledge obtained by this group to other light element hydrides, it will become possible to establish guidelines for enhancing superconducting critical temperature to near room temperature.

This research was featured in the electronic version of Scientific Reports on Thursday, March 17, 2016