By Andrew Grant
After a two-decade hiatus, superconductors are again heating up.
A compound of hydrogen and sulfur, when crushed at more than a million times Earth’s standard atmospheric pressure, appears to whisk electrical current along without resistance at temperatures up to 203 kelvins. That’s not exactly balmy — it’s −70° Celsius — but the current record holder performs its magic at temperatures no higher than 164 kelvins.
A room-temperature superconductor would enable robust energy storage devices, MRI machines that don’t require liquid helium coolant and a new generation of levitating trains. But after more than a century of intense research, physicists still aren’t sure exactly which compounds are capable of reaching that goal. Any new superconductor, even one that requires high-pressure equipment installed in only a handful of labs worldwide, could lead physicists to more practical materials.