A magical material that could effortlessly conduct electricity at room temperatures would likely transform civilization, reclaiming energy otherwise lost to electrical resistance and opening possibilities for novel technologies.
Yet a claim of such a room-temperature superconductor published in March in the prestigious journal Nature, drew doubts, even suspicion by some that the results had been fabricated.
But now, a group of researchers at the University of Illinois Chicago reports that it has verified a critical measurement: the apparent vanishing of electrical resistance.
This result does not prove that the material is a room-temperature superconductor, but it may motivate other scientists to take a closer look.
Ranga P. Dias, a professor of mechanical engineering and physics at the University of Rochester in New York and a key figure in the original research, had reported that the material appeared to be a superconductor at temperatures as warm as 70 degrees Fahrenheit — much warmer than other superconductors — when squeezed at a pressure of 145,000 pounds per square inch, or about 10 times what is exerted at the bottom of the ocean’s deepest trenches.
The high pressure means the material is unlikely to find practical use, but if the discovery is true, it could point the way to other superconductors that truly work in everyday conditions.
The claim was met with skepticism because several scientific controversies have swirled around Dr. Dias, and other scientists trying to replicate the results had failed to detect any signs of superconductivity.
Dr. Dias has founded a company, Unearthly Materials, to commercialize the research, raising $16.5 million in financing so far from investors.
The new measurements, revealed in a preprint paper posted this month, come from a team led by Russell J. Hemley, a professor of physics and chemistry at the University of Illinois Chicago. Dr. Hemley declined to comment because the paper had not yet been accepted by a scientific journal.
Nonetheless, he is well regarded in the field, and his report could lead to a more positive reconsideration of Dr. Dias’s superconducting claim.
“It may convince some people,” said James J. Hamlin, a professor of physics at the University of Florida who has been a persistent critic of Dr. Dias’s research. “It makes me think there might be something to it.”
Dr. Dias’s material is made of lutetium, a silvery-white rare earth metal, along with hydrogen and a little bit of nitrogen. Using a sample provided by Dr. Dias, Dr. Hemley’s laboratory performed independent measurements of the electrical resistance as the material was cooled under high pressure.
Dr. Hemley and his colleagues observed sharp drops in electrical resistance in the material. Although those occurred at temperatures of up to 37 degrees Fahrenheit, about 30 degrees cooler than Dr. Dias described, that would still be warm compared to other superconductors. The transition temperatures varied depending on how tightly the material was squeezed.
“They have done the electrical resistance measurements to confirm our results,” Dr. Dias said in an interview. “It does show the pressure dependence of the transition temperature, which goes very well with what we reported in our Nature paper in March.”
Dr. Hemley’s measurements do not provide proof of superconductivity. It is possible that the material is simply a very good conductor and not a superconductor.
The report did not include measurements to determine whether there were zero magnetic fields inside. That phenomenon, known as the Meissner effect, is considered to be definitive evidence of a superconductor.
Some of Dr. Dias’s earlier papers have provoked heated debate. Critics including Dr. Hamlin say crucial details were sometimes left out about how data from experiments were processed. The journal Nature even retracted a paper published in 2020 that made an earlier superconductor claim despite the objections of Dr. Dias and the other authors who say the findings remain valid.
Dr. Hamlin has also pointed out that swathes of Dr. Dias’s doctoral thesis at Washington State University in 2013 were copied, virtually word for word, from the work of other scientists, including Dr. Hamlin’s own doctoral thesis.
Dr. Dias acknowledges that he copied other people’s work in his thesis, saying he should have included citations. He denies scientific wrongdoing in his earlier papers.
“I have never knowingly or intentionally engaged in any act of plagiarism of anybody’s scientific work,” Dr. Dias said. “It was an oversight.”
The results of the research from Dr. Hemley’s team argue that Dr. Dias has indeed discovered something new in the lutetium-hydrogen-nitrogen material.
Lilia Boeri, a professor of physics at Sapienza University of Rome, said it was evident that this was not a repeat of a scientific scandal two decades ago when it turned out that J. Hendrik Schön, a researcher at Bell Labs in New Jersey, had made up his data in claiming a series of breakthrough discoveries.
“This is a completely different story in the sense that he, for sure, has produced something and measured something,” Dr. Boeri said of Dr. Dias.
But, she added, “It’s really unclear whether this is an indication of superconductivity or simply that he has found some interesting electronic transmission of some type.”
In recent years, materials known as hydrides have proved promising in the search for superconductors that work at warmer temperatures, although so far they all require crushing pressures. Dr. Dias said it was hydrides that led him to the lutetium-hydrogen-nitrogen mixture.
However, Dr. Boeri said that while other hydrides fit with the standard theory of superconductivity, Dr. Dias’s substance does not.
An earlier paper, by Dr. Hemley, along with Adam Denchfield, a graduate student in physics at the University of Illinois Chicago, and Hyowon Park, an assistant professor of physics at the same university, attempts to explain why, saying researchers have overlooked subtleties in the electronic structure of the lutetium-hydrogen-nitrogen compound that could provide an explanation of a higher superconducting temperature.
They propose that the elements in Dr. Dias’s material could be configured in different structures. The most prevalent structure could be responsible for the color change and other observed properties, while the superconducting currents flow through a smaller amount of a different structure in the compound. That could explain why not all of the samples, not even all of those created in Dr. Dias’s laboratory, are superconducting.
But Dr. Boeri is not swayed.
“The theoretical arguments are completely strange,” she said. Dr. Boeri said a material with high superconducting temperature, at least one that follows the conventional theory, requires a very stiff lattice structure that this material does not possess, and the paper does not discuss this issue.
Eva Zurek, a professor of chemistry at the University at Buffalo who has collaborated with both Dr. Hemley and Dr. Dias on other projects, was initially skeptical but now has partially changed her mind.
Numerical simulations of superconductors include simplifications to make the calculations. Dr. Hemley’s paper argues that the calculations should be performed somewhat differently, and when Dr. Zurek’s group tried those modifications, they arrived at the same answers.
“I realized it’s not impossible,” Dr. Zurek said. “I wouldn’t rule it out right away, let’s put it like that.”
