A magical material that can effortlessly conduct electricity at room temperature would likely transform civilization, recover energy otherwise lost to electrical resistance and open up possibilities for new technologies.
But a claim of such a room-temperature superconductor, published in March in the prestigious journal Nature, raised doubts, some even suspecting that the results were fabricated.
But now a group of researchers at the University of Illinois Chicago report verifying a critical measurement: the apparent disappearance of electrical resistance.
This result doesn’t prove the material is a superconductor at room temperature, 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 study, had reported that the material appeared to be a superconductor at temperatures as high 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 troughs.
The high pressure makes it unlikely that the material will be of practical use, but if the discovery is true, it could point the way to other superconductors that actually work in everyday conditions.
The claim was met with skepticism as several scientific controversies surrounding Dr. Dias and other scientists who tried to replicate the results had found no signs of superconductivity.
Dr. Dias has formed a company, Unearthly Materials, to commercialize the research, raising $16.5 million in funding from investors to date.
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 at Chicago. Dr. Hemley declined to comment because the article had not yet been accepted by a scientific journal.
Nevertheless, 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 die-hard critic of Dr. dias. “It makes me think there might be something going on.”
The material from Dr. Dias is made of lutetium, a silvery white rare earth metal, along with hydrogen and a little bit of nitrogen. Using a sample from Dr. Dias ran the lab of Dr. Hemley made independent measurements of electrical resistance while the material was cooled under high pressure.
Dr. Hemley and his colleagues saw sharp drops in electrical resistance in the material. Although those took place in temperatures 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 pressed.
“They took the electrical resistance measurements to confirm our results,” said Dr. Dias in an interview. “It does show the pressure dependence of the transition temperature, which fits very well with what we reported in our Nature paper in March.”
The measurements of Dr. Hemley provide no evidence of superconductivity. It is possible that the material is just 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 the definitive proof of a superconductor.
Some previous articles by Dr. Dias have sparked heated debate. Critics, including Dr. Hamlin, say crucial details were sometimes left out about how data from experiments were processed. The journal Nature has even retracted a 2020 article that made a previous 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 parts of Dr. Dias at Washington State University in 2013 were taken almost verbatim from the work of other scientists, including Dr. Hamlin.
Dr. Dias acknowledges that he copied the work of others in his dissertation and said he should have included quotes. He denies scientific misconduct in his earlier articles.
“I have never knowingly or intentionally been guilty of plagiarizing anyone’s scientific work,” said Dr. dias. “It was a mistake.”
The results of the research of Dr. Hemley claim that Dr. Dias has indeed discovered something new in the material lutetium-hydrogen-nitrogen.
Lilia Boeri, a professor of physics at Sapienza University of Rome, said it was clear this was not a repeat of a science scandal two decades ago when J. Hendrik Schön, a researcher at Bell Labs in New Jersey, was revealed to have invented his data by claiming a series of groundbreaking discoveries.
“This is a whole different story in that he definitely produced something and measured something,” said Dr. Boer about Dr. dias.
But, she added, “It’s really unclear if this is an indication of superconductivity or just that he found some interesting electronic transmission.”
In recent years, materials known as hydrides have shown promise in the search for superconductors that operate at higher temperatures, though all so far require breaking pressure. Dr. Dias said it was the hydrides that led him to the lutetium-hydrogen-nitrogen mixture.
Dr. However, Boeri said that while other hydrides fit the standard theory of superconductivity, Dr. Dias doesn’t.
An earlier paper, by Dr. Hemley, along with Adam Denchfield, a physics graduate student at the University of Illinois Chicago, and Hyowon Park, an assistant professor of physics at the same university, try to explain why, saying that researchers have overlooked subtleties in the electronic structure of the lutetium-hydrogen-nitrogen compound that could explain a higher superconducting temperature.
They suggest that the elements in Dr. Slides can be configured in different structures. The most abundant structure could be responsible for the color change and other observed properties, as the superconducting currents flow through a smaller amount of another structure in the compound. That might explain why not all samples, not even all samples found in Dr. Dias are made, are superconducting.
But Dr. Boeri does not allow himself to be influenced.
“The theoretical arguments are completely strange,” she said. Dr. Boeri said that a material with a high superconducting temperature requires a very rigid lattice structure that this material does not have, and the paper does not discuss this issue.
Eva Zurek, a chemistry professor at the University at Buffalo who has worked with both Dr. Hemley as Dr. Dias collaborated on other projects was skeptical at first, but has now partially changed his mind.
Numerical simulations of superconductors include simplifications to make the calculations. The article by Dr. Hemley argues that the calculations should be done somewhat differently, and when Dr. Zurek trying adjustments, they came to the same answers.
“I realized it’s not impossible,” said Dr. Zurek. “I wouldn’t rule it out right away, let’s put it that way.”
