{"id":190,"date":"2023-10-20T13:30:12","date_gmt":"2023-10-20T11:30:12","guid":{"rendered":"https:\/\/physicsworld.com\/?p=110713"},"modified":"2023-12-30T01:12:42","modified_gmt":"2023-12-30T00:12:42","slug":"superconductivity-damaged-as-researchers-look-to-move-on-from-retractions","status":"publish","type":"post","link":"https:\/\/hadamard.com\/c\/superconductivity-damaged-as-researchers-look-to-move-on-from-retractions\/","title":{"rendered":"Superconductivity ‘damaged’ as researchers look to move on from retractions"},"content":{"rendered":"

Update 07\/11\/2023: The Lu-N-H paper (Nature<\/i> 615<\/b> 244)<\/a> has since been retracted by the journal<\/a>.<\/strong><\/p>\n

 <\/p>\n

\u201cI\u2019m going to introduce a new material for the first time.\u201d So said the condensed-matter physicist Ranga Dias<\/a> to a packed conference room at the March meeting of the American Physical Society<\/a> in Las Vegas earlier this year. The material in question was nitrogen-doped lutetium hydride, or Lu-N-H, and Dias went on to describe measurements claiming to have seen evidence for superconductivity at a remarkable 294 K (a balmy 20 \u00b0C) under a pressure of 1 GPa (10\u00a0kbar).<\/p>\n

Based at the University of Rochester in the US, Dias claimed to have observed many signatures of superconductivity such as the electrical resistance dropping to zero at a particular transition temperature and the material expelling magnetic field lines. He and his colleagues also measured the sample\u2019s specific heat, which showed a characteristic response at the transition temperature.<\/p>\n

Their finding appeared to mark the culmination of a century-long quest in condensed-matter physics: the search for materials that superconduct under ambient conditions. Yet following the talk no-one spoke a word and there was no wild celebration. Dias simply finished his talk and passed the microphone over to the next speaker.<\/p>\n

A member of the audience asked if there would be questions. \u201cWe don\u2019t have time,\u201d responded session chair Minta Akin from the Lawrence Livermore National Laboratory, her reply greeted with an audible groan from the room.<\/p>\n

The atmosphere seemed very different from a previous APS March meeting in 1987 \u2013 the famous \u201cWoodstock of physics\u201d in New York City that took place just after the first high-temperature superconductors had been discovered.<\/p>\n

Back then the physicists Georg Bednorz and Alex M\u00fcller<\/a> had set the world of condensed-matter physics alight after discovering the year before that a material containing copper oxide, lanthanum and barium became superconducting at around 35\u00a0K. This was some 50% higher than the previous record of 23\u00a0K that had been achieved more than a decade earlier in niobium-germanium (Nb3<\/sub>Ge).<\/p>\n

The new \u201ccuprate\u201d materials caused such a buzz because they were not metals but insulators and they offered the possibility of finding new stoichiometries and compounds that could potentially reach even higher transition temperatures.<\/p>\n

A room-temperature superconductor was the holy grail, holding out the hope for a wide-range of applications from ultra-efficient energy grids to medical applications that require powerful magnets.<\/p>\n

Bednorz and M\u00fcller later won the 1987 Nobel Prize for Physics for the discovery and in the decades that followed researchers created new cuprate-based compounds that reached transition temperatures of 133\u00a0K at ambient pressure and 166\u00a0K at a pressure of around 30\u00a0GPa.<\/p>\n

 <\/p>\n

From cuprates to hydrides<\/h3>\n

While the cuprates had been the de facto <\/i>superconducting kings for the past couple of decades, that all began to change in the mid-2010s. In 2015 Mikhail Eremets<\/a> and colleagues at the Max Planck Institute for Chemistry and the Johannes Gutenberg University Mainz, both in Germany, observed superconductivity at 203\u2009K in a sample of hydrogen sulphide.<\/p>\n

Although the material needed to be squeezed to 150\u00a0GPa (Nature<\/i> 525<\/b> 73<\/a>), in 2018 a group led by Russell Hemley<\/a>, then at George Washington University in the US, reported superconductivity at 260\u00a0K in lanthanum superhydride, albeit still under pressures of over 180\u00a0GPa, work that was published in 2019 (Phys. Rev. Lett<\/i>. 122<\/b> 027001<\/a>).<\/p>\n

That same year Eremets\u2019 team reported superconductivity at temperatures up to 250\u00a0K\u00a0 <\/span>in lanthanum hydride at 170\u00a0GPa (Nature<\/i> 569<\/b> 528<\/a>).<\/p>\n

Work on these so-called binary hydrides \u2013 compounds that contain hydrogen and one other element such as hydrogen sulphide \u2013 sparked a \u201cgold rush\u201d in the search for high-temperature superconductors.<\/p>\n

But what was most exciting is that they were predicted entirely from first-principles calculations, with theory agreeing almost perfectly with experiment.<\/p>\n

Dias\u2019 inconsiderate behaviour has harmed the reputation of the field and it may take a few years to repair the damage<\/p>\n

nLilia Boeri<\/span><\/p><\/blockquote>\n

\u201cThe hydrides have probably been the single most exciting discovery in superconductivity after the cuprates, and an amazing success story of the interplay between theory and experiment,\u201d says theoretical physicist Lilia Boeri<\/a> from the University of Rome La Sapienza.<\/p>\n

Dias and colleagues entered the high-temperature superconductivity game in 2020. Using his experience squeezing hydrogen to high pressure (see box below), Dias\u2019s group published a paper on carbonaceous sulphur hydride<\/a> that claimed to show superconductivity at 288\u00a0K under a pressure of about 260\u2009GPa (Nature<\/i> 586<\/b> 373<\/a>). <\/span><\/p>\n

Around the same time Dias co-founded a company \u2014 Unearthly Materials \u2014 to commercialize room-temperature superconductors and that year the work was awarded a 2020 Physics World<\/em> Breakthrough of the Year<\/a>. <\/span><\/p>\n

In 2021 Dias was even named as a TIME100 Next innovator<\/a> for his work. \u201cLet\u2019s be clear: hoverboards, magnetic levitation trains and resistance-free power\u202flines are not coming this year or next,\u201d noted\u00a0Time<\/em> magazine. \u201cBut thanks to Ranga\u202fDias, they\u2019re closer than they ever were.\u201d \u00a0<\/span><\/p>\n

But not everything was as it seemed. In 2021 concerns were raised by researchers about some of the data processing in the paper, in particular the manner in which a background had been subtracted from the resistance measurements to show the sample falling to zero resistance after the transition temperature. <\/span><\/p>\n

Then, in September 2022, the group\u2019s Nature<\/i> paper was retracted<\/a>. \u201cWe have now established that some key data processing steps \u2013 namely, the background subtractions applied to the raw data used to generate the magnetic susceptibility plots \u2013 used a non-standard, user-defined procedure,\u201d noted an editorial update written by the authors of the original paper.<\/p>\n

All nine authors on the paper disagreed with the decision by Nature<\/i> to retract, although the University of Rochester began three internal inquiries, two of which were completed in May 2022, and another after the retraction. Rochester announced that the investigations had found no evidence of misconduct but have not released\u00a0<\/span>full details of the inquiries.<\/p>\n

Dias was undeterred and, after giving his talk at the APS meeting this year, his team\u2019s work on Lu-N-H was published<\/a>, again in Nature<\/i> (615<\/b> 244)<\/a>.<\/p>\n

In April, a patent listing Dias as the inventor was published<\/a> (although filed in April 2022) for a lutetium hydride material that can superconduct at room temperature. No details of the material\u2019s exact stoichiometry were, however, given. But just as with the 2020 Nature<\/i> paper, questions were raised around the background subtraction in the new study.<\/p>\n

There were also concerns that the stated success rate of measuring superconductivity at high temperatures in Lu-N-H samples was only about 35%, when one would hope that all samples made to a certain recipe would be superconducting to aid reproducibility.<\/p>\n

I still feel that hydride superconductivity has a good chance of eventually providing a superconductor at ambient conditions<\/p>\n

nDavid Ceperley<\/span><\/p><\/blockquote>\n

And when other researchers tried to reproduce the findings, they failed. Di Peng from the Institute of Solid State Physics in Hefei, China, and colleagues, for example, found some signs of a transition at about 240\u2009K, but suggest they are not indicative of superconductivity (arXiv:2307.00201<\/a>).<\/p>\n

Theorists who tried to explain the high-temperature superconductivity found themselves struggling too. Boeri and colleagues recently showed that not only could they not identify a single compound in the Lu-N-H phase diagram that could explain Dias\u2019 extraordinary claims, but also that Lu-N-H hydrides are intrinsically low-temperature superconductors (Nature Commun.<\/i> 14<\/b> 5367<\/a>). \u201cThere is no single theoretical paper that finds a plausible explanation for Dias\u2019 results,\u201d she says.<\/p>\n

Support for Dias\u2019s work, however, came from Hemley, who is now at the University of Illinois Chicago. Having been given material prepared by Dias\u2019 team, Hemley and colleagues measured the electrical resistance of the samples under various pressures, finding evidence for superconductivity as high as 276 K at 15 kbar (arXiv:2306.06301<\/a>).<\/p>\n

\u201cOur measurements are in excellent agreement with what\u2019s reported in the Nature<\/i> paper,\u201d Hemley told Physics World<\/i>. \u201cMoreover, the magnitude of the drop is even larger than that of the earlier data.\u201d<\/p>\n

Hemley says that theoretical analysis he and colleagues have carried out show that the electronic structure of Lu-N-H is \u201dremarkable\u201d (arXiv: 2305.18196<\/a>).<\/p>\n

\u201cWith these continued discoveries, the pursuit of superconductors that function at or even above room temperature, together with the quest for stabilizing these materials near ambient pressure, remains very exciting,\u201d he adds.<\/p>\n

But there was further bad news in store for Dias. On 1 September 2023 Nature<\/i> published an editor\u2019s note<\/a> alerting readers that Dias\u2019 Lu-N-H paper is being investigated.<\/p>\n

\u201cThe reliability of data presented in this manuscript is currently in question,\u201d Nature<\/i> said. \u201cAppropriate editorial action will be taken once this matter is resolved.\u201d<\/p>\n

According to a report in the Wall Street Journal<\/i><\/a> in late September, eight of the 11 authors of the Lu-N-H paper had written to Tobias R\u00f6del, a senior editor at Nature<\/i>, requesting that the paper be retracted, claiming that Dias \u201chas not acted in good faith in regard to the preparation and submission of the manuscript\u201d.<\/p>\n

Apparently, R\u00f6del replied to them within a few days noting: \u201cWe are in absolute agreement with your request that the paper be retracted.\u201d So far, the only researchers to stick to their findings are Dias and two of his current PhD students.<\/p>\n

David Ceperley<\/a> from the University of Illinois, who penned a News & Views article for Nature<\/i><\/a> about the Lu-N-H results, says he is \u201cdisappointed\u201d that Nature<\/i> did not do a better job of reviewing the paper in the first place.<\/p>\n

\u201cWe were only provided with the accepted manuscript and not the data files or referee comments,\u201d he says. \u201cIt was only after the paper came out that we learned of some the problems that could have been found earlier.\u201d<\/p>\n

 <\/p>\n

\n

Allegations rack up for Ranga Dias<\/h2>\n

Originally from Sri Lanka, Ranga Dias graduated with a degree in physics from the University of Colombo in 2006. He then moved to the US, obtaining a PhD in 2013 from Washington State University studying materials under high pressure before doing a postdoc at Harvard University on metallic hydrogen with Isaac Silvera. Dias moved to the University of Rochester in 2017, where he began working on superconductivity in hydrides under high pressures. Apart from the controversial hydride papers (see main text), there have also been accusations of plagiarism and misconduct in other areas of his work, with James Hamlin at the University of Florida concluding Dias plagiarized as much as a fifth of his PhD thesis (Science<\/i> 380<\/strong> 227<\/a>). A spokesperson for Dias has told Science<\/i> that Dias is \u201caddressing the issues directly with his thesis adviser\u201d. Then in August Physical Review Letters<\/i> retracted a study from Dias that it had published in 2021 (127<\/strong> 016401<\/a>) describing the electrical properties of manganese disulfide, which included a large reduction in electrical resistance under pressure. The retraction notice said that an internal investigation by four independent experts revealed \u201cserious doubts about the origins of three of the low-temperature resistance curves\u201d. The statement was signed by all authors except Dias, who said he \u201cdoes not agree with the retraction\u201d.<\/p>\n<\/div>\n

Moving on<\/h3>\n

What will happen regarding Dias\u2019 group is unknown. In August the University of Rochester announced it is investigating Dias\u2019 work again<\/a>, although when that investigation will be complete is unknown. \u201cUnfortunately, Dias\u2019 inconsiderate behaviour has harmed the reputation of the field and it may take a few years to repair the damage,\u201d says Boeri.<\/p>\n

That view is backed by condensed-matter physicist James Hamlin<\/a> from the University of Florida, who examined some of Dias\u2019 group\u2019s work. \u201cI do think the whole saga is damaging to science in general, and superconductivity research more so and more broadly it\u2019s fuel for anti-science types,\u201d he told Physics World<\/i>. \u201cIt could have an impact on funding for high pressure research and that would be unfortunate given that it\u2019s been such a fruitful area with so many exciting recent developments.\u201d<\/p>\n

Hamlin also thinks that scientific research journals should broaden their communications to include all authors of the paper rather than just the corresponding author when potential research misconduct is raised. \u201cAll authors are subject to potential reputational harm from a misconduct allegation, so all authors should be privy to the relevant communications from editors from the very beginning,\u201d he adds.<\/p>\n

Despite these issues, work on the hydrides is progressing. In July Guangtao Liu of Jilin University, China, and colleagues found superconductivity up to 110\u00a0K at a pressure of 80\u00a0GPa in the ternary hydride LaBeH8<\/sub> (Phys. Rev. Lett.<\/i> 130<\/b> 266001<\/a>).<\/p>\n

Although this temperature is not that high, these ternary compounds are exciting because they have a wider potential variety of structures than their binary cousins, which could expand the materials available for high-temperature superconductivity. \u201cThe field [of hydride research] is healthy and has the potential to yield many more ground-breaking results in future,\u201d adds Boeri.<\/p>\n

Ceperley agrees. \u201cI still feel that hydride superconductivity has a good chance of eventually providing a superconductor at ambient conditions, which would have vast technological applications,\u201d he notes. \u201cThe space of possible compounds and fabrication methods is so vast it may take some time to find them.\u201d<\/p>\n

As for Dias, he declined to comment for this article although in previous media comments he said he stood by his results.<\/p>\n

In July Physics World<\/i> even offered to publish an interview with Dias and sent a set of written questions to him via 30 Point<\/a>, a US-based PR agency acting on Dias\u2019s behalf. Despite having agreed to answer the questions, Dias later pulled out of the interview.<\/p>\n

Physics World <\/i>has since learned that 30 Point no longer works with Dias.<\/p>\n

The post Superconductivity \u2018damaged\u2019 as researchers look to move on from retractions<\/a> appeared first on Physics World<\/a>.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Update 07\/11\/2023: The Lu-N-H paper (Nature 615 244) has since been retracted by the journal.   \u201cI\u2019m going to introduce a new material for the first time.\u201d So said the condensed-matter physicist Ranga Dias to a packed conference room at the March meeting of the American Physical Society in Las Vegas earlier this year. The… Continue reading Superconductivity ‘damaged’ as researchers look to move on from retractions<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-190","post","type-post","status-publish","format-standard","hentry","category-allgemein","entry"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/posts\/190","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/comments?post=190"}],"version-history":[{"count":1,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/posts\/190\/revisions"}],"predecessor-version":[{"id":320,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/posts\/190\/revisions\/320"}],"wp:attachment":[{"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/media?parent=190"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/categories?post=190"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hadamard.com\/c\/wp-json\/wp\/v2\/tags?post=190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}