Pushing Towards Room-Temperature Superconductivity

Two independent studies report superconductivity at record high temperatures in hydrogen-rich materials under extreme pressure.

Superconductivity, the ability of a material to conduct electricity without any resistance, was first observed in 1911 in solid mercury below a critical temperature (Tc) of 4.2 K.Eversince, countless scientists have been searching for a material whose Tc exceeds room temperature. For a long time this holy grail seemed unattainable—a linear extrapolation of research progress from 1911 to 1970 suggested that Tc would reach room temperature around the year 2840! The discovery of high-temperature superconductivity in copper oxides raised Tc above liquid helium temperature. Since 1994, one of the copper oxides has held the record for the highest Tc (133 K at atmospheric pressure and 164 K under high pressure). Despite intense research, it took another 20 years to beat this record in a completely new class of systems: In 2015, the compression of hydrogen sulfide to 150 GPa, or about 40% of the pressure found in Earth’s core, yielded a Tc of 203 K [1]. Remarkably, two independent groups, the first led by Russell Hemley at the George Washington University in Washington, DC [2], and the second by Mikhail Eremets at the Max Planck Institute for Chemistry, Germany [3], have now reported experiments indicating that a hydride of lanthanum compressed to 170–185 GPa has a Tc of 250–260 K [2, 3]. The results bode well for the search for room-temperature superconductors—the reported materials could already work without the need for cooling on an average winter night in the Arctic!