Negative pressure Superconducting paper at room temperature that was withdrawn

Negative pressure? Superconducting paper at room temperature that was withdrawn during data analysis

A groundbreaking paper claiming to show the first room-temperature superconductor was withdrawn by the journal Nature over concerns about its data analysis after claims the results had been tampered with.

Superconductors are materials that have no electrical resistance and are useful in a variety of applications, including NMR machines, quantum computers, and particle accelerators. Currently, however, all superconducting materials require very low temperatures (below 150 K) or extremely high pressures. Room-temperature superconductors would revolutionize the way electric charges are handled and are considered by some to be one of the “holy grails” of chemistry.

The retracted article, authored by a team led by Ranga Dias from the University of Rochester, USA, and Ashkan Salamat from the University of Nevada in Las Vegas, USA, was published in October 2020 and appears to have come a little closer to that goal. The team claimed to have found superconductivity in carbonaceous sulfur hydride (CSH) at a temperature of around 288 K (15 °C), but at an intense pressure of 155 GPa – about 1.55 million times the pressure of Earth’s atmosphere. The result was widely acclaimed, with suggestions it might win a Nobel Prize, and seen as heralding a possible new era in superconductors. Since then it has been viewed more than 100,000 times.

The evidence for superconductivity in the hydride was based on an analysis of magnetoresistance and susceptibility data. However, questions arose in November 2020 when Jorge Hirsch of the University of California, San Diego, USA requested the raw vulnerability data, only to have his request denied. This led to Nature adding a disclaimer stating that there were “unspoken restrictions on access to the data behind it”. [the] paper’ before the authors published the raw data last December.

Hirsch then began further research with Dirk van der Marel of the University of Geneva. According to Hirsch, their analysis showed that the team could not have achieved these results either with the method described in the work or with the raw data obtained. Additionally, the duo said it was not possible to produce the team’s findings “without employing techniques that can only be characterized as data modification and manipulation.” By this time, Hirsch, along with Frank Marsiglio of the University of Alberta, Canada, had also challenged the paper’s resistance data, leading to a paper on “Questions Raised” in Nature in August 2021.

Now the paper has been retracted, with Nature reporting that “certain key data processing steps — namely, applied background subtractions … used a non-standard custom procedure.” The details of this procedure were not specified in the document and the validity… was questioned. The editors of Nature conclude that “we believe these processing issues undermine confidence in the published magnetic susceptibility data set and withdraw the article accordingly.”

Hirsch welcomed the decision but says the revocation notice doesn’t address his claims. “Nature makes it seem like she’ll accept the authors’ claim that what they call ‘raw data’ is actually data measured in a lab using lab equipment and a physical sample,” says Hirsch. “In fact, however, we have provided Nature with clear mathematical evidence that what the authors call ‘raw data’ is actually not. Hirsch called on the National Science Foundation, which funded the work, and the University of Rochester to conduct “a thorough examination of the facts.”

Dias points out to Chemistry World that “the revocation request does not challenge the observed state of physical superconductivity of the CSH material,” only the methodology, and that the team’s findings both in terms of properties and in terms of the synthesis and determination were replicated using the structure. “Not all authors of the article agree with the retraction,” says Dias. ‘We stand by our work and will resubmit the paper containing the raw data plot of susceptibility as recommended by Nature.’