article ｜Wang Fang
In 2020, Ranga Dias, a physicist at the University of Rochester in the United States, and his colleagues published a sensational cover article on Nature.
They claim to have discovered a room temperature superconductor—a material that can achieve superconductivity at high pressure conditions near room temperature.
Although it is just fine particles of carbon, sulfur and hydrogen forged under extreme pressure, one hopes that one day this material will produce various variants, providing lossless grids and cheap magnets for NMR imager , magnetic levitation railways, atomic accelerators and nuclear fusion reactors, etc.
However, this hope is being dashed. Nature withdrew the research paper on September 26, saying data questions raised by other scientists over the past two years have weakened the credibility of one of the two key signs of superconductivity that Dias' team claims.
Researchers said a micro diamond clamp extruded hydrogen-containing samples into a room-temperature superconductor. Image source: MIKE BRADLEY/BIGSLIDE
University of Florida experimental condensed matter physicist James Hamlin said: "For some time, people have had many questions about the relevant results." UC San Diego theoretical physicist Jorge Hirsch, who has long criticized the study, said that withdrawing the paper was not enough. He believes this conceals evidence of scientific misconduct.
"I think this is the real problem," Hirsch said. "You can't just leave it alone and say 'Oh, this is a disagreement'."
This withdrawal was unusual because the editor of Nature made the decision despite the opposition of all nine authors of the paper.
Dias said: "We stick to our work, it has been proven experimentally and theoretically." Senior collaborator and Host Nevada physicist Ashkan Salamat said he was confused and disappointed by the decision of the editorial board of Nature.
In 2015, Mikhail Eremets, an experimental physicist at the Max Planck Institute of Chemistry in Germany, and his colleagues reported the first superconducting hydride, a mixture of hydrogen and sulfur. Some theoretical physicists believe that adding a third element to the mixture will bring a new variable that is able to approach ambient pressure or room temperature.
2020 Dias and colleagues added carbon, crushed the mixture in an diamond anvil, and heated it with a laser to produce a new substance. In Nature, they claimed that they realized the superconductivity of carbon-sulfur hydrogen system under conditions of 267GPa and 287K (nearly 15℃), but they were quickly questioned.
In response to some criticism, Dias and Salamat published a paper on preprint server arXiv in 2021, which contained some original sensitivity data. "It asks more questions than answers," said Brad Ramshaw, a physicist at Cornell quantum materials. "The process from raw data to publishing data is very opaque."
"I think that (some of the public data provided by Dias and Salamat) is fabricated," Hirsch said. He also pointed out that it has suspicious similarities with the data in a 2009 paper called " Physical Review Express ". The study is the same as one of the authors of this Nature paper, but was withdrawn last year due to the inaccurate susceptibility data.
Eremets believes that the Dias team is unwilling to disclose more research details and said that it tried to repeat the experiment at least 6 times, but all failed. Salamat said he welcomed to their laboratory to observe, "We are open."
Dias said the team plans to resubmit the paper to Nature without any background cuts. Meanwhile, they did not slow down, Dias and Salamat jointly founded a company that developed commercial room temperature superconductors.
"We are on the cliff of the new era of high temperature superconducting ." Salamat said.
