The scientific paper announcing the wonder material dubbed “red matter”, which researchers claimed earlier this year was the world’s first room-temperature superconductor, has been retracted by Nature. The retraction marks the end of a year-long saga over room-temperature superconductors, following the failed replications of LK-99, another material that held the promise of revolutionising electronics and drove an online frenzy.
Unlike LK-99, which was first published in the relatively little-known Journal of the Korean Crystal Growth and Crystal Technology, and took researchers by surprise, the work on red matter, or N-doped lutetium hydride, was published in Nature and came with the imprimatur of apparent scientific rigour.
But many people were still initially sceptical of the claims, both because of the singular nature of the material – there is no other superconductor that works at room temperature and low pressures – and the fact that one of the lead authors, Ranga Dias at the University of Rochester in New York state, had had a previous superconductor paper in Nature retracted in 2022.
Now, the red matter paper has been retracted. “There were very, very good reasons to doubt since the beginning about this paper,” says Lilia Boeri at the University of Rome in Italy. “I think it’s actually surprising that it took quite this long to retract this paper.”
Eight of the 11 authors have concerns over “the provenance of the investigated materials, the experimental measurements undertaken and the data-processing protocols applied”, they write in a note accompanying the retraction. These issues, they say, “undermine the integrity of the published paper”.
Three of the authors didn’t express an opinion on the retraction, including Dias, who has come under increasing scrutiny since the paper was first published in March.
In August, Dias had another paper retracted, in Physical Review Letters, and other researchers accused him of plagiarising sections of his PhD thesis. He has rejected both the Physical Review Letters and past Nature retraction, and hasn’t publicly commented on claims of plagiarism.
Neither Dias nor the group of eight authors who requested the latest retraction have responded to a request for comment from New Scientist.
For many researchers, this is the final nail in the coffin for red matter, after attempts at replication earlier this year repeatedly failed.
“This has been a huge waste of time,” says Graeme Ackland at the University of Edinburgh, UK.
While it is commendable that researchers tried to faithfully replicate the results, there is still the question of how the paper made it to publication, he says. “It’s embarrassing for the field.”
“Everybody was surprised that this paper came out in Nature,” says Boeri.
“This has been a deeply frustrating situation. We were aware that this paper would likely be greeted with scepticism by many in the community given the retraction of an earlier related paper by this group,” said Karl Ziemelis, chief applied and physical sciences editor at Nature, in a statement. “Decisions about what to accept for publication are not always easy to make and there may be conflicts, but we strive to take an unbiased position and to ensure the interests of the community always drive our deliberations.”
“Rigorous peer review is always key; indeed, as is so often the case, the highly qualified expert reviewers we selected raised a number of questions about the original submission, which were largely resolved in later revisions,” he said. “What the peer review process cannot detect is whether the paper as written accurately reflects the research as it was undertaken. This was the concern raised recently by a number of the authors, as detailed in the retraction notice.”
Although there is a chance that this casts a shadow on the field, it is a healthy sign that there was scepticism from the very beginning, says Boeri.