High-temperature superconductivity yields another secret

Researchers have determined that quantum rather than classical physical behaviour is responsible for superconductivity in high-pressure hydrogen sulphide, a result which could benefit the design of high-temperature superconductors, said the University of Cambridge.

Cambridge H2S - High-temperature superconductivity yields another secret

Last year, German researchers identified superconductivity in H2S at -70°C, said to be the highest temperature yet. To get it working, the gas needed compressing to around one million atmospheres.

A collaboration between the University of the Basque Country, the Donostia International Physics Center, and researchers from the University of Cambridge have been trying to find out why it superconducts.

At low pressure hydrogen atoms form one short and one long bond with neighbouring sulphur atoms, and one theory is that superconductivity can occur once the hydrogen atoms sit exactly half way between the sulphur atoms.

When the researchers modelled hydrogen atoms as classical particles, one million atmospheres was not enough to achieve symmetry, while switching to the quantum interpretation of hydrogen atoms as waves yielded pressures similar to the experimental results.

“That we are able to make quantitative predictions with such a good agreement with the experiments is exciting and means that computation can be confidently used to accelerate the discovery of high temperature superconductors,” said Professor Chris Pickard of Cambridge.

According to Cambridge, as this study shows that the quantum motion of hydrogen can strongly affect the electron-phonon interaction that allows superconduction, room-temperature superconductivity might be possible in other hydrogen-rich compounds.

Results on the high-temperature superconductivity are published in Nature.

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