Scientists have observed superconductivity — or zero resistance to electricity — in a material cooled to 250 Kelvin, or minus 23°C, the highest superconducting temperature achieved since the discovery of the phenomenon 108 years ago.
Present-day superconductors need to be cooled to extreme low temperatures — between 4 and 77K — and have limited applications such as in magnetic resonance imaging devices.
An international team of researchers on Wednesday announced superconductivity in lanthanum hydride material at 250K but at unimaginably high pressures, more than a million times the atmospheric pressure on Earth, or half the pressure at the Earth’s core.
The highest temperatures achieved in the laboratory until now had been about 205K under similarly high pressures. Scientists caution that the extreme pressures preclude immediate practical applications of such superconductors but view the new record as a major advance in the quest for room-temperature superconductivity.
Scientists envision that room temperature superconductors if achieved and if commercially feasible could lead to novel applications such as near-lossless electricity transmission or levitating frictionless trains.
“Our experiments show it is possible to reach very high temperatures,” Mikhail Eremets, a senior materials scientist at the Max Planck Institute for Chemistry in Germany, who led the new research, told The Telegraph over the phone.
“The future challenge is to synthesise good materials that can display superconductivity at such temperatures but without such extreme pressures,” Eremets said.
A Dutch physicist, Heike Kamerlingh Onnes, had discovered superconductivity in 1911 when he cooled mercury to below 4K. In the decades since then, scientists have tried to push up the temperatures at which materials become superconductors.
In the 1980s, researchers discovered superconductivity in a class of materials called perovskites at temperatures of about 92K, much higher than earlier but still a great distance from room temperature.
Five years ago, Eremets and his colleagues themselves broke an earlier record of 164K by showing that hydrogen sulfide — the compound that gives bad eggs their distinct smell — becomes a superconductor at 200K when compressed to about 2 million atmospheric pressures.
In their latest experiment, Eremets and his collaborators in Germany, Poland, Russia and the US have increased the superconducting temperature by an additional 50K to about 250K. They have described their experiments in a paper to be published in the journal Nature on Thursday.
Given the potential for exploring similar novel materials, scientists are hopeful that room temperature superconductivity is closer now than before.
James Hamlin, a physicist at the University of Florida, in a commentary on the research in the same journal said: “…. It seems more likely than ever that the dream of room-temperature superconductivity might be realised in the near future.”
“The grand challenge will shift from pushing the necessary temperatures higher to pushing pressures lowers,” Hamlin wrote in the commentary.