A high-temperature superconductor warmly welcomed

Discovery of this beginning of the century or premature announcement? Caution is advised since publication, on March 8 in Nature, of the recipe for a revolutionary material, a superconductor at room temperature, by an American team from the University of Rochester. Superconductivity is the disappearance of all electrical resistance in a material, therefore the end of electrical losses, opening up infinite application prospects. So far, it has only been observed at temperatures below zero. It is even used around -196 degrees Celsius to create the intense magnetic fields of MRIs or to deploy a few cables in electrical transport networks. But the Holy Grail would be to have such materials at milder temperatures of around twenty degrees.

This is what the team of Ranga Dias, a physicist at the University of Rochester, claims to have discovered. Its mixture of hydrogen, nitrogen and lutetium is superconducting at 20.8 degrees Celsius, but at a pressure of 10,000 bars, or about ten times the pressure at 1,000 meters deep. It may seem like a lot, but it’s a hundred times less than a series of recent works that have studied materials from this family. This pressure obviously complicates the deployment of large-scale applications, but the result remains important and… controversial.

Ranga Dias is indeed already well known for other disputed works. In September 2022even though the article which has just appeared was being examined by Nature, this same journal retracted its October 2020 article which had already broken records. The researcher presented a mixture of superconducting carbon, sulfur and hydrogen at 15 degrees Celsius and a pressure of 267 GigaPascal (one GigaPascal is 10,000 bars). The journal’s editors pointed out that the methodology used by the researchers “was called into question” following several outside criticisms. But the team did not accept this decision and, a month ago, submitted a new experience in preprint, almost confirming these early works : a superconductivity at – 13 degrees Celsius and 133 GigaPascal.

Peculiarities not explained

To make matters worse, one of the authors of this retracted article, but not a co-signer of the last article in Nature (he is still thanked), also saw one of his 2009 publications retracted in 2021.

In 2017, another work co-signed by Ranga Dias, claiming to have discovered another holy grail of chemistry, metallic hydrogenhad been much contested by his peers.

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