It may be too early to lament the demise of a room-temperature superconductivity claim.
On September 26, the newspaper Nature retracted an article that described material that appeared become a superconductor at a cozy 15° Celsius (Serial number: 10/14/20). The notice unsettled many people in the field. But a new experiment conducted just days after the retraction supports the world record temperature claim, say an eyewitness and others familiar with the experiment.
Superconductors carry electricity without resistance, which means they are useful for transmitting energy efficiently. They could save huge amounts of energy that is wasted in conventional metal cables. They are currently used to create powerful magnetic fields for medical imaging and particle physics experiments, as well as serving as components in high-performance circuits and even to levitate high-speed trains. But to work, superconducting materials generally need to be cooled well below 0°C, and many to temperatures close to absolute zero, or -273°C.
When researchers announced in 2020 that a sample made of hydrogen, sulfur, and a little carbon became a superconductor at record temperatures, dreams of room-temperature superconductors seemed about to come true. One problem was that the material had to be under enormous pressures, around 2.6 million times atmospheric pressure, roughly the pressure found in parts of the Earth’s core. Still, the discovery hailed a potential scientific and technological revolution.
In the two years since then, controversy has swirled around the report. The maelstrom focuses on how the researchers prepared and processed data that showed changes in a magnetic property known as susceptibility. Ultimately, the publishers of Nature took the unusual step of retracting the article over the objections of the researchers. “We have now established that some key data processing steps… used a non-standard user-defined procedure,” the editors write in Nature in the retraction. “The details of the procedure were not specified in the document and the validity of the record theft was subsequently questioned.”
The new experiment is not a duplicate of the one reported in the retracted article, but the researchers replicated a part of their research that raised red flags in the scientific community.
Ranga Dias, a physicist at the University of Rochester who led the research on the now-retracted paper, led the new measurements at the Advanced Photon Source at Argonne National Laboratory in Lemont, Illinois. “We have been working on this experiment for almost six months. building and reconfirming the correct methodology”, says Dias. “I would say the data we got at Argonne is more compelling, not just comparable,” to the data in the retracted Nature paper.
“The experiment was carried out over two days, September 27 and 28,” says physicist Nilesh Salke of the University of Illinois Chicago, who was not affiliated with the original research. Salke’s role at Argonne was to test a sample of the material in question with X-rays while showing magnetic susceptibility associated with high-temperature superconductivity. “We saw the first sign of susceptibility on September 27, consistent with the claims reported in the retracted Nature paper.”
This latest twist is unlikely to end the controversy that arose from the initial claim, at least in the mind of physicist Jorge Hirsch of the University of California, San Diego. Hirsch has been one of the most vocal critics of the claim of superconductivity at room temperature.
“I didn’t know he would back down, but I was hoping he would back down,” says Hirsch, who was not affiliated with either the original experiment or the new one. He says he asked the authors for the raw data from the earlier study a month after it was published, but was denied. “The authors said, ‘No, we can’t give you the data because our lawyers said it would affect our patent rights.'”
With the intervention of Nature, Hirsch finally got the numbers. What he saw disturbed him. Hirsch is skeptical that high-temperature superconductivity is possible in these kinds of hydrogen-based materials in general, but says he’s opposed based on the way the data was handled.
“There were real issues between the raw data and the published data,” says Hirsch. he he believes that NatureThe retraction of does not go far enough. “It’s not that the data hasn’t been processed correctly.” Together with the physicist Dirk van der Marel of the University of Geneva, Hirsch Dig deeper into data issues In an article published on September 15 in the International Journal of Modern Physics B. “Our analysis mathematically proves that the raw data was not measured in the lab. They were manufactured.”
Dias and his colleagues deny any irregularities in their data or analysis and are moving forward with experiments like the one at Argonne. But that work awaits peer review. For now, NatureThe shrinkage of reinforces existing doubts about superconductivity at room temperature.
“In the end, all of this has to be validated by different groups to get the answer,” says Hirsch.