Nature withdraws controversial superconductivity paper by controversial physicist

Physicist Ranga Dias is being investigated by his institution, the University of Rochester in New York.Credit: Lauren Petracca/New York Times/Redux/eyevine

The environment retracted the controversial paper1 which states the discovery of a superconductor – a substance that carries electrical currents with zero resistance – that can operate at room temperature and low pressure.

The text of the retraction notice states that it was requested by eight co-authors. “They expressed the opinion as researchers who contributed to the work that the published paper does not accurately reflect the provenance of the materials investigated, the experimental measurements made and the data processing procedures used,” it said, adding that the authors are co-authors. “we conclude that these issues undermine the integrity of the published paper”.

It is the third retraction of a highly detailed paper by the two lead authors, physicists Ranga Dias of the University of Rochester in New York and Ashkan Salamat of the University of Nevada, Las Vegas . The environment he withdrew a separate paper last year again Physical Review Letters withdrew one this August3. It explains a particularly big problem for Dias, who some researchers say is part of his PhD. Dias disputed the first two withdrawals and did not respond to the latest. Salamat approved the two this year.

“It’s no surprise now that Dias and Salamat’s group has a third high-profile paper being retracted,” said Paul Canfield, a physicist at Iowa State University in Ames and Ames National Laboratory. Many physicists had noticed The environment being withdrawn as inevitable after two more – and mostly since then The Wall Street Journal again Science it was reported in September that 8 of the paper’s 11 authors – including Salamat – had requested it in a letter to the journal.

Dias and Salamat did not respond to a request for comment from The environmentNews team. The retraction says that he and his two other co-authors – Nuggari Khalvashi-Sutter and Sasanka Munasinghe, both of Rochester – “never stated whether they agree or disagree with this retraction”.

Doubts from the start

This year’s report by Dias and Salamat is the second major claim for superconductivity to crash and burn in 2023. In July, a different team from the first company in Seoul explained. a crystalline purple material called LK-99 – made of copper, lead, phosphorus and oxygen – which they say shows superconductivity at normal pressure and at temperatures up to at least 127°C (400 kelvin). There was a lot of excitement online and many attempts to reproduce the results, but researchers quickly reached a consensus that the material was not a superconductor at all.

Superconductors are important in many applications, from magnetic resonance imaging machines to particle colliders, but their use is limited by the need to store them at very low temperatures. For decades, researchers have been developing new materials with the dream of finding one that works best without refrigeration.

Experts in the field have been sceptical since the publication of this year’s Dias and Salamat paper, said Lilia Boeri, a physicist at Sapienza University of Rome. He says this is partly due to the conflicts in the group and the other is that the latest paper was not written in a way that he considers to be of high quality.

“Almost every serious physicist I know saw right away that there were serious problems with this work,” said Peter Armitage, a physicist at Johns Hopkins University in Baltimore, Maryland. In particular, members of the public objected to the electrical resistance measurements, saying that it was unclear whether the area had actually dropped to zero, or whether Dias and Salamat had removed a background signal from a critical piece of resistance to create an appearance. that it did. Critics say there should be no need to remove the background from this type of measurement. In today’s note, the journal said, “The journal’s investigation and post-publication review concluded that these concerns are credible, significant and unresolved.”

Armitage adds that the paper’s publication also raises questions about the editorial review process at The environment and why the reviewers did not catch the problems.

“The highly qualified peer reviewers we selected raised a number of questions about the original submission, which were largely resolved in recent revisions,” said Karl Ziemelis, senior editor of environmental science at The Environment. “What the peer review process cannot determine is whether the written paper accurately reflects the research as it was done.”

“Decisions about what to accept for publication are not always easy to make,” continued Ziemelis. “And there may be arguments, but we strive to take an impartial position and ensure that the public interest always drives our discussions.”

A loud noise

The Environment published the retracted paper on March 8. That week, Dias himself presented the results to a private audience only at the meeting of the American Physical Society in Las Vegas. Due to the loud noise of the crowd gathered outside the doors of the room – where the conference workers were limited to entering to avoid violating the fire regulations – Dias briefly described a compound made of hydrogen, lutetium and a small amount of nitrogen that was a superconductor at temperatures up to 21 ° C. (294 kelvin) when maintained at a pressure of around 1 gigapascal (10,000 times atmospheric pressure).

Many groups have already created and tested similar hydrogen-rich substances, called hydrides, after the landmark discovery in 2015. A team led by physicist Mikhail Eremets at the Max Planck Institute for Chemistry in Mainz, Germany, reported. superconductivity in a hydrogen-sulphur compound at −70 °C (203 kelvin); at the time, this was the highest operating temperature for a superconductor. But Eremets equipment required a much higher pressure of 145 gigapascals (1.4 million times atmospheric pressure) – compared to the pressure conditions at the Earth’s core.

Since then, researchers have developed hydride superconductors that are getting closer and closer to working at room temperature, but they all work only under high pressure. When Dias and Salamat published their paper on The environment in March, they seem to have taken an important step towards understanding a matter that can be used in a practical way.

But some experts were wary of the start The environment retreat. And others said they quickly found the new claims impossible. For example, the material described in the paper was supposed to have three hydrogen atoms for every lutetium atom. But in that case, lutetium will tend to donate an electron to each hydrogen, resulting in a type of salt, said Artem Oganov, a material scientist at the Skolkovo Institute of Science and Technology in Moscow. “You get an insulator or a very poor metal,” he says – not a superconductor.

One lab claims to have reproduced Dias and Salamat’s results using a sample provided by the Rochester group.7. But many others, who tried to create their own samples and practical tests, could not. And in the meantime, other causes for concern have emerged. The investigation was launched by Physical Review Letters before it retracted its paper by Dias and Salamat found “obvious data manipulation”, as The environmentThe news team reported in July. And the investigation started by The environmentThe journal’s team after receiving confidential information from this year’s journal found that the “reliability of the published results is questionable”, according to a September news release. Science.

Honesty concerns

Armitage does not think that Dias and Salamat will be able to continue with the research, pointing to the findings of the investigation and the alleged plagiarism in Dias’s PhD thesis. The University of Rochester confirmed that The environment that it has launched an investigation into the integrity of Dias’ work, which is now being carried out by outside experts. The university’s spokesperson did not answer questions about whether the institution is still disciplining Dias. UNLV did not respond The environment questions about whether Salamat is being investigated, saying that “UNLV does not publicly discuss personnel matters”, but is “committed to maintaining the highest campus standards of research integrity”.

Canfield says the Dias-Salamat collaboration has spread “dirty vapours” in the field, “frightening young researchers and funding agencies”.

“I have some colleagues who are afraid that this case of Dias casts a shadow of doubt on the integrity of our sector in general,” said Eremets.

Ho-Kwang Mao, director of the Center for High Pressure Science and Technology Advanced Research in Beijing, has a holy spirit. “I don’t think it will affect the funding of superconductivity research without a careful review, which is not really bad,” he said.

Hai-Hu Wen, director of the Center for Superconducting Physics and Materials at Nanjing University in China, agrees. “In fact, it seems very easy to get funding for superconductivity research as some government officials seem to be swayed by the prospect of a room temperature superconductor,” he said.

But Boeri says he has heard researchers complain that the controversies — allegations of PhD thesis plagiarism and findings of apparent data manipulation — have made it difficult to recruit students to work on superconductors.

“We are facing a huge communication problem, to make people understand that the field is healthy – that even though there may be bad apples, the social standards are very high,” he said.

“Resolute people continue to do amazing and exciting work,” Armitage said. “Sure, they can be discouraged by this nonsense, but it won’t stop science.”