A team of 11 scientists reported in March in the journal Nature that they had discovered a room-temperature superconductor. Eight of those scientists have now asked Nature to retract their paper.
That pits them against the man who led the research: Ranga P. Dias, a professor of mechanical engineering and physics at the University of Rochester in New York. In the past few years, Dr. Dias has made several extraordinary scientific claims, but he has also been embroiled in a series of allegations of scientific misconduct.
The retraction request will add to the scrutiny of Dr. Dias and Unearthly Materials, a company that Dr. Dias founded to turn the superconductivity discoveries into commercial products. Unearthly Materials has raised $16.5 million from investors.
It also raises questions about how editors at Nature, one of the most prestigious journals in the scientific world, vet submissions and decide which are worthy of publication. Nature had already published and retracted a previous paper from Dr. Dias’s group describing a different purported superconductor.
Superconductors are materials that can conduct electricity without any electrical resistance, and one that works in everyday conditions could find wide use in the transmission of electricity and for powerful magnets used in MRI machines and future fusion reactors. Superconductors discovered to date require ultracold temperatures.
In the Nature paper, Dr. Dias and his co-authors described how lutetium hydride — a material made of lutetium, a silvery-white metal, and hydrogen — gained new electronic properties when a tiny bit of nitrogen was added. When squeezed to a pressure of 145,000 pounds per square inch, the material not only changed color, from blue to red (leading Dr. Dias to give it the nickname of redmatter), but also turned into a superconductor, able to effortlessly carry electricity at temperatures as warm as 70 degrees Fahrenheit, the scientists said in the Nature paper.
Skeptics almost immediately questioned the findings, which led Nature to re-examine the research.
The co-authors said Dr. Dias kept most of them out of the loop of the post-publication review for several months.
In their letter to Tobias Rödel, a senior editor at Nature, dated Sept. 8, the co-authors described what they regarded as significant flaws in the research and said that they believed that “Dr. Dias has not acted in good faith in regard to the preparation and submission of the manuscript.”
The Wall Street Journal reported on the letter on Tuesday.
The writers of the letter included five recent graduate students who worked in Dr. Dias’s lab. They said that they raised concerns during the preparation of the scientific paper. “Those concerns included clearly misleading and/or inaccurate representations in the manuscript,” they wrote.
They said that Dr. Dias did make some changes, but that “our concerns largely were dismissed by Dr. Dias, and some of us were instructed by Dr. Dias not to probe further into the issues raised and/or not to worry about such concerns.”
The letter said that the graduate students felt constrained in what they could say at the time because they relied on Dr. Dias for academic and financial support.
Those signing the letter seeking a retraction included Ashkan Salamat, a professor of physics at the University of Nevada, Las Vegas, and a co-founder of Unearthly Materials, serving as president and chief executive. That was a change from May, when Dr. Salamat and Dr. Dias defended the paper in a rebuttal of concerns raised by other scientists.
Dr. Salamat did not respond to requests for comment. A spokesman for Dr. Dias said Dr. Salamat was no longer an employee of Unearthly Materials, but remained a shareholder.
The only authors of the March paper who did not sign the letter were Dr. Dias, a graduate student who is currently a member of his research group and a former undergraduate student who, according to his LinkedIn profile, now works at Unearthly Materials.
Before the letter was sent, Dr. Dias urged the authors to reconsider. “I am obligated to defend myself and notify you of my request that you cease and desist from signing and/or sending the proposed letter,” he wrote in a letter shared on social media by the science journalist Dan Garisto. Dr. Dias’s spokesman confirmed the contents of the letter.
The retraction request was nonetheless sent to Nature. The Wall Street Journal reported that Dr. Rödel replied in an email, “We are in absolute agreement with your request that the paper be retracted.”
Karl Ziemelis, the chief physical sciences editor at Nature, said in a statement: “We are currently carefully investigating concerns related to the reliability of the data in this paper. We can also confirm that we are in correspondence with the authors regarding all concerns.”
He added, “We expect to take action in the near future.”
A retraction of the lutetium hydride paper would be the third retraction in the past year for Dr. Dias.
In 2020, Dr. Dias and his collaborators described in a paper, also published in Nature, a different material that was superconducting at room temperatures, but only at crushing pressures similar to those found near the center of the Earth.
After some scientists questioned the data in the 2020 paper, Nature conducted a review and then retracted the paper in September 2022 over the objections of Dr. Dias and all of the other authors.
In August, the journal Physical Review Letters retracted another of Dr. Dias’s papers, one published in 2021 that described the electronic transformations of manganese sulfide under changing pressure. Critics again pointed to data that looked fishy, and after outside reviewers took a closer look, the editors of the journal agreed.
“The findings back up the allegations of data fabrication/falsification convincingly,” the editors wrote in an email to the authors of the paper in July. Nine of the 10 authors of the manganese sulfide paper agreed to the retraction. Dr. Dias was the only holdout, insisting that the work contained no manipulation or fabrication.
A similar sequence of events is playing out again with the lutetium hydride paper. Brad J. Ramshaw, a professor of physics at Cornell University, was involved in the review that led to the retraction of the 2020 Nature paper.
After the lutetium hydride paper was published, Dr. Ramshaw noticed oddities in the electrical resistance measurements.
He reached out to James J. Hamlin, a professor of physics at the University of Florida, who had previously posted an analysis of the 2020 superconductivity paper. In early May, Dr. Hamlin and Dr. Ramshaw wrote up their concerns about the lutetium hydride data and sent them to Nature.
Without revealing the identities of Dr. Hamlin and Dr. Ramshaw, the concerns were sent to Dr. Dias, and at the end of May, Dr. Dias and Dr. Salamat sent back their rebuttal. On June 26, Dr. Hamlin and Dr. Ramshaw responded to the rebuttal, detailing how the procedure described in Dr. Dias’s paper to subtract out a background signal in the resistance measurements could not have produced the graphs shown in the paper.
“I don’t know of anyone in the field of superconductivity who would do what they did to the data,” Dr. Ramshaw said in an interview.
Nature recruited four referees to weigh the contentions. They largely sided with Dr. Hamlin and Dr. Ramshaw. One referee wrote that Dr. Dias and Dr. Salamat “did not provide satisfactory response to several issues” and wondered why the authors “are not willing or able to provide clear and timely responses.”
In the Sept. 8 letter, the co-authors said most of them did not know of the concerns until July 6, after Dr. Dias and Dr. Salamat had already responded.
The letter from the co-authors described problems with the data or the analysis for several of the figures in the paper. The letter also disclosed that almost all of the lutetium hydride samples were bought commercially — some happened to contain some nitrogen impurities — and were not made in Dr. Dias’s laboratory using the recipe described in the Nature paper.
In April 2022, the graduate students approached Dr. Dias to express their concerns, and he responded that they could remove their names as authors or they could allow the paper to proceed.
“At the time, neither choice seemed tenable given that Dr. Dias was in control of our personal, academic and financial circumstances, as our mentor and supervisor,” the letter writers said.
Dr. Dias’s spokesman said Dr. Dias never intimidated his students. “All discussions were open and available to all co-authors,” the spokesman said. “The co-authors made collective decisions about the publication.”