Material sets superconducting record

Superconductors conduct electricity with no resistance, possibly enabling technology like more-efficient power grids. There’s now a new competitor in the race to make a superconductor that works at room temperature. Researchers measured superconductivity at 15 °C in a carbonaceous sulfur hydride (Nature 2020, DOI: 10.1038/s41586-020-2801-z), almost 30 °C higher than the previous record.

Ranga Dias of the University of Rochester says the material has the advantages of previously investigated hydrogen-rich metal hydride superconductors, like H₃S, and adding C allows more possible combinations to produce a high-performing material. They used a photochemical process to treat elemental carbon, sulfur, and hydrogen before using a traditional diamond anvil to compress the mixture to its final form.

Electrical conductivity and magnetic field measurements suggest the material may have two superconducting phases, one phase forming at about 140 GPa and one at 220 GPa. The latter remained stable to 15 °C. The researchers’ anvil broke near 275 GPa, but Dias says their data suggest the material may keep superconducting at higher temperatures.

The researchers were not able to measure the stoichiometry or structure of their superconductor, but calculations suggest that it may be an H₂S lattice with pores filled with CH₄.

Eva Zurek of the University at Buffalo, who has made theoretical predictions of this material, says the strength of C, S, and H bonds means this system may produce materials stable at ambient pressure—key for any practical application. Dias says that is the group’s next goal.