One of 2020’s hottest physics results was the demonstration that a hydrogen-rich material can conduct without electrical resistance at 15C, the average temperature of a spring day in Paris. But this achievement required another condition that isn’t fulfilled on the banks of the Seine: a pressure of 267 GPa, which is close to that of Earth’s core. Researchers, including Lilia Boeri of Sapienza University of Rome, are optimistic about the prospects of easing this requirement. Boeri presented two possible pathways to achieving superconductivity at closer-to-ambient conditions at the recent March Meeting of the American Physical Society.

The road to room-temperature superconductivity traces back to a 1960s prediction that hydrogen, if sufficiently squeezed, could turn into a metal that superconducts at high temperatures. While the pressure for hydrogen metallization is exceptionally large, superconductivity hunters sought similar effects at lower pressures using hydrogen-rich compounds called hydrides. The discovery of the first hydride superconductor finally came in 2015, sparking a “hydride rush” that continues to shatter record after record for superconducting temperatures.

According to Boeri, much of this progress was spurred by theoretical advances of the last 15 years. Armed with a new density-functional theory for superconductors and with ever more powerful crystal-structure-prediction methods, theorists have guided experiments by calculating, from first principles, what potential superconductors can be synthesized and what the critical temperatures are at which their superconductivity kicks in.

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