Physicists achieve room-temperature superconductivity at lowest pressure ever recorded

Less than two years ago, the scientific community was stunned by the discovery of a material that could achieve room-temperature superconductivity. Now, a team of physicists at the University of Nevada, Las Vegas (UNLV) has raised the bar again by reproducing the feat at the lowest pressure ever recorded.

Specifically, this means science is closer than ever to a usable, reproducible material that could one day revolutionize the way energy is transported.

UNLV physicist Ashkan Salamat and his colleague Ranga Dias, a physicist at the University of Rochester, have discovered room-temperature superconductivity for the first time. To achieve this feat, they used chemical methods to synthesize a mixture of carbon, sulfur and hydrogen first into a metallic state and then further synthesized it into a room-temperature superconducting state using extremely high pressures (267 gigapascals), conditions that can only be found in nature near the center of the Earth.

In less than two years, researchers have now been able to accomplish this feat at just 91 GPa—about one-third the pressure originally reported. The new findings appear as an advance publication this month in Chemical Communications.

A super discovery

By making detailed adjustments to the composition of carbon, sulfur and hydrogen used in the initial breakthrough, the researchers have now been able to produce a material at lower pressures and maintain its superconducting state.

"These are pressures that are difficult to understand and assess outside of the lab, but our current trajectory suggests that it may be possible to achieve relatively high superconducting temperatures at consistently lower pressures -- our ultimate goal," said Gregory Alexander Smith, lead author of a paper on the study and a graduate student researcher at UNLV's Nevada Extreme Conditions Laboratory (NEXCL). "At the end of the day, if we want to make devices that are beneficial to society's needs, then we have to lower the pressures required to make them."

Although the pressures are still extremely high -- about a thousand times what you'd experience at the bottom of the Mariana Trench in the Pacific Ocean -- they continue to race toward the goal of getting closer to zero. The race is growing exponentially at UNLV as researchers gain a better understanding of the chemical relationships between the carbon, sulfur and hydrogen that make up the material.

"Our knowledge of the relationship between carbon and sulfur is evolving rapidly, and we are searching for ratios that lead to significantly different, more efficient reactions than those initially observed," said Salamat, who directs UNLV's NEXCL and contributed to the latest research. "Observing such different phenomena in a similar system shows the richness of Mother Nature. There is still a lot to learn, and each new advance brings us closer to the precipice of everyday superconducting devices."

The Holy Grail of Energy Efficiency

Superconductivity is a remarkable phenomenon that was first observed more than a century ago, but only at very low temperatures, so there was no thought of any practical applications. Only in the 1960s did scientists theorize that the feat might be possible at higher temperatures. The discovery of room-temperature superconductors by Salamat and colleagues in 2020 excited the scientific community in part because the technology supports the flow of electric current with zero resistance, meaning that energy through a circuit can be conducted infinitely with no power loss. This could have major implications for energy storage and transmission, and support everything from better cellphone batteries to more efficient energy grids.

“The global energy crisis shows no signs of slowing down, and rising costs are due in part to the U.S. energy grid losing approximately $30 billion per year due to inefficiencies in current technology,” said Salamat. “For societal change to happen, we need to lead with technology, and the work happening today, I believe, is at the forefront of tomorrow’s solutions.”

According to Salamat, the properties of superconductors could support a new generation of materials that could fundamentally change the energy infrastructure of the United States and other countries.

“Imagine harnessing energy in Nevada and sending it across the country without any energy loss,” he said. “This technology could one day make that possible.”